diff --git a/.github/workflows/check-whitespace.yml b/.github/workflows/check-whitespace.yml
index 8c4358d..ad3466a 100644
--- a/.github/workflows/check-whitespace.yml
+++ b/.github/workflows/check-whitespace.yml
@@ -1,8 +1,9 @@
 name: check-whitespace
 
-# Get the repo with the commits(+1) in the series.
+# Get the repository with all commits to ensure that we can analyze
+# all of the commits contributed via the Pull Request.
 # Process `git log --check` output to extract just the check errors.
-# Add a comment to the pull request with the check errors.
+# Exit with failure upon white-space issues.
 
 on:
   pull_request:
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 6ed6a9e..c35200d 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -1,4 +1,4 @@
-name: CI/PR
+name: CI
 
 on: [push, pull_request]
 
@@ -7,6 +7,7 @@
 
 jobs:
   ci-config:
+    name: config
     runs-on: ubuntu-latest
     outputs:
       enabled: ${{ steps.check-ref.outputs.enabled }}${{ steps.skip-if-redundant.outputs.enabled }}
@@ -77,6 +78,7 @@
             }
 
   windows-build:
+    name: win build
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'
     runs-on: windows-latest
@@ -97,6 +99,7 @@
         name: windows-artifacts
         path: artifacts
   windows-test:
+    name: win test
     runs-on: windows-latest
     needs: [windows-build]
     strategy:
@@ -127,6 +130,7 @@
         name: failed-tests-windows
         path: ${{env.FAILED_TEST_ARTIFACTS}}
   vs-build:
+    name: win+VS build
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'
     env:
@@ -178,6 +182,7 @@
         name: vs-artifacts
         path: artifacts
   vs-test:
+    name: win+VS test
     runs-on: windows-latest
     needs: vs-build
     strategy:
@@ -210,6 +215,7 @@
         name: failed-tests-windows
         path: ${{env.FAILED_TEST_ARTIFACTS}}
   regular:
+    name: ${{matrix.vector.jobname}} (${{matrix.vector.pool}})
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'
     strategy:
@@ -219,14 +225,25 @@
           - jobname: linux-clang
             cc: clang
             pool: ubuntu-latest
+          - jobname: linux-sha256
+            cc: clang
+            os: ubuntu
+            pool: ubuntu-latest
           - jobname: linux-gcc
             cc: gcc
+            cc_package: gcc-8
+            pool: ubuntu-latest
+          - jobname: linux-TEST-vars
+            cc: gcc
+            os: ubuntu
+            cc_package: gcc-8
             pool: ubuntu-latest
           - jobname: osx-clang
             cc: clang
             pool: macos-latest
           - jobname: osx-gcc
             cc: gcc
+            cc_package: gcc-9
             pool: macos-latest
           - jobname: linux-gcc-default
             cc: gcc
@@ -236,7 +253,9 @@
             pool: ubuntu-latest
     env:
       CC: ${{matrix.vector.cc}}
+      CC_PACKAGE: ${{matrix.vector.cc_package}}
       jobname: ${{matrix.vector.jobname}}
+      runs_on_pool: ${{matrix.vector.pool}}
     runs-on: ${{matrix.vector.pool}}
     steps:
     - uses: actions/checkout@v2
@@ -251,6 +270,7 @@
         name: failed-tests-${{matrix.vector.jobname}}
         path: ${{env.FAILED_TEST_ARTIFACTS}}
   dockerized:
+    name: ${{matrix.vector.jobname}} (${{matrix.vector.image}})
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'
     strategy:
@@ -259,7 +279,8 @@
         vector:
         - jobname: linux-musl
           image: alpine
-        - jobname: Linux32
+        - jobname: linux32
+          os: ubuntu32
           image: daald/ubuntu32:xenial
         - jobname: pedantic
           image: fedora
@@ -289,6 +310,7 @@
     - uses: actions/checkout@v2
     - run: ci/install-dependencies.sh
     - run: ci/run-static-analysis.sh
+    - run: ci/check-directional-formatting.bash
   sparse:
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'
@@ -310,6 +332,7 @@
       run: ci/install-dependencies.sh
     - run: make sparse
   documentation:
+    name: documentation
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'
     env:
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 908330a..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,60 +0,0 @@
-language: c
-
-cache:
-  directories:
-    - $HOME/travis-cache
-
-os:
-  - linux
-  - osx
-
-osx_image: xcode10.1
-
-compiler:
-  - clang
-  - gcc
-
-matrix:
-  include:
-    - env: jobname=linux-gcc-default
-      os: linux
-      compiler:
-      addons:
-      before_install:
-    - env: jobname=linux-gcc-4.8
-      os: linux
-      dist: trusty
-      compiler:
-    - env: jobname=Linux32
-      os: linux
-      compiler:
-      addons:
-      services:
-        - docker
-      before_install:
-      script: ci/run-docker.sh
-    - env: jobname=linux-musl
-      os: linux
-      compiler:
-      addons:
-      services:
-        - docker
-      before_install:
-      script: ci/run-docker.sh
-    - env: jobname=StaticAnalysis
-      os: linux
-      compiler:
-      script: ci/run-static-analysis.sh
-      after_failure:
-    - env: jobname=Documentation
-      os: linux
-      compiler:
-      script: ci/test-documentation.sh
-      after_failure:
-
-before_install: ci/install-dependencies.sh
-script: ci/run-build-and-tests.sh
-after_failure: ci/print-test-failures.sh
-
-notifications:
-  email: false
diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index 711cb91..0e27b53 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -499,6 +499,33 @@
  - Where required libraries do not restrict us to Python 2, we try to
    also be compatible with Python 3.1 and later.
 
+
+Program Output
+
+ We make a distinction between a Git command's primary output and
+ output which is merely chatty feedback (for instance, status
+ messages, running transcript, or progress display), as well as error
+ messages. Roughly speaking, a Git command's primary output is that
+ which one might want to capture to a file or send down a pipe; its
+ chatty output should not interfere with these use-cases.
+
+ As such, primary output should be sent to the standard output stream
+ (stdout), and chatty output should be sent to the standard error
+ stream (stderr). Examples of commands which produce primary output
+ include `git log`, `git show`, and `git branch --list` which generate
+ output on the stdout stream.
+
+ Not all Git commands have primary output; this is often true of
+ commands whose main function is to perform an action. Some action
+ commands are silent, whereas others are chatty. An example of a
+ chatty action commands is `git clone` with its "Cloning into
+ '<path>'..." and "Checking connectivity..." status messages which it
+ sends to the stderr stream.
+
+ Error messages from Git commands should always be sent to the stderr
+ stream.
+
+
 Error Messages
 
  - Do not end error messages with a full stop.
diff --git a/Documentation/MyFirstContribution.txt b/Documentation/MyFirstContribution.txt
index b20bc8e..63a2ef5 100644
--- a/Documentation/MyFirstContribution.txt
+++ b/Documentation/MyFirstContribution.txt
@@ -905,19 +905,34 @@
 themselves, you'll need to prepare the patches. Luckily, this is pretty simple:
 
 ----
-$ git format-patch --cover-letter -o psuh/ master..psuh
+$ git format-patch --cover-letter -o psuh/ --base=auto psuh@{u}..psuh
 ----
 
-The `--cover-letter` parameter tells `format-patch` to create a cover letter
-template for you. You will need to fill in the template before you're ready
-to send - but for now, the template will be next to your other patches.
+ . The `--cover-letter` option tells `format-patch` to create a
+   cover letter template for you. You will need to fill in the
+   template before you're ready to send - but for now, the template
+   will be next to your other patches.
 
-The `-o psuh/` parameter tells `format-patch` to place the patch files into a
-directory. This is useful because `git send-email` can take a directory and
-send out all the patches from there.
+ . The `-o psuh/` option tells `format-patch` to place the patch
+   files into a directory. This is useful because `git send-email`
+   can take a directory and send out all the patches from there.
 
-`master..psuh` tells `format-patch` to generate patches for the difference
-between `master` and `psuh`. It will make one patch file per commit. After you
+ . The `--base=auto` option tells the command to record the "base
+   commit", on which the recipient is expected to apply the patch
+   series.  The `auto` value will cause `format-patch` to compute
+   the base commit automatically, which is the merge base of tip
+   commit of the remote-tracking branch and the specified revision
+   range.
+
+ . The `psuh@{u}..psuh` option tells `format-patch` to generate
+   patches for the commits you created on the `psuh` branch since it
+   forked from its upstream (which is `origin/master` if you
+   followed the example in the "Set up your workspace" section).  If
+   you are already on the `psuh` branch, you can just say `@{u}`,
+   which means "commits on the current branch since it forked from
+   its upstream", which is the same thing.
+
+The command will make one patch file per commit. After you
 run, you can go have a look at each of the patches with your favorite text
 editor and make sure everything looks alright; however, it's not recommended to
 make code fixups via the patch file. It's a better idea to make the change the
diff --git a/Documentation/MyFirstObjectWalk.txt b/Documentation/MyFirstObjectWalk.txt
index 45eb84d..ca26794 100644
--- a/Documentation/MyFirstObjectWalk.txt
+++ b/Documentation/MyFirstObjectWalk.txt
@@ -58,14 +58,19 @@
 
 Add usage text and `-h` handling, like all subcommands should consistently do
 (our test suite will notice and complain if you fail to do so).
+We'll need to include the `parse-options.h` header.
 
 ----
+#include "parse-options.h"
+
+...
+
 int cmd_walken(int argc, const char **argv, const char *prefix)
 {
 	const char * const walken_usage[] = {
 		N_("git walken"),
 		NULL,
-	}
+	};
 	struct option options[] = {
 		OPT_END()
 	};
@@ -195,9 +200,14 @@
 ourselves; however, we should call `git_default_config()` if we aren't calling
 any other existing config callbacks.
 
-Add a new function to `builtin/walken.c`:
+Add a new function to `builtin/walken.c`.
+We'll also need to include the `config.h` header:
 
 ----
+#include "config.h"
+
+...
+
 static int git_walken_config(const char *var, const char *value, void *cb)
 {
 	/*
@@ -229,8 +239,14 @@
 to target, as well as the `prefix` argument of `cmd_walken` and your `rev_info`
 struct.
 
-Add the `struct rev_info` and the `repo_init_revisions()` call:
+Add the `struct rev_info` and the `repo_init_revisions()` call.
+We'll also need to include the `revision.h` header:
+
 ----
+#include "revision.h"
+
+...
+
 int cmd_walken(int argc, const char **argv, const char *prefix)
 {
 	/* This can go wherever you like in your declarations.*/
@@ -624,9 +640,14 @@
 ----
 
 Let's start by calling just the unfiltered walk and reporting our counts.
-Complete your implementation of `walken_object_walk()`:
+Complete your implementation of `walken_object_walk()`.
+We'll also need to include the `list-objects.h` header.
 
 ----
+#include "list-objects.h"
+
+...
+
 	traverse_commit_list(rev, walken_show_commit, walken_show_object, NULL);
 
 	printf("commits %d\nblobs %d\ntags %d\ntrees %d\n", commit_count,
@@ -697,7 +718,7 @@
 ----
 static void walken_object_walk(struct rev_info *rev)
 {
-	struct list_objects_filter_options filter_options = {};
+	struct list_objects_filter_options filter_options = { 0 };
 
 	...
 ----
diff --git a/Documentation/RelNotes/2.35.0.txt b/Documentation/RelNotes/2.35.0.txt
new file mode 100644
index 0000000..fa5a731
--- /dev/null
+++ b/Documentation/RelNotes/2.35.0.txt
@@ -0,0 +1,402 @@
+Git 2.35 Release Notes
+======================
+
+Updates since Git 2.34
+----------------------
+
+Backward compatibility warts
+
+ * "_" is now treated as any other URL-valid characters in an URL when
+   matching the per-URL configuration variable names.
+
+ * The color palette used by "git grep" has been updated to match that
+   of GNU grep.
+
+
+UI, Workflows & Features
+
+ * "git status --porcelain=v2" now show the number of stash entries
+   with --show-stash like the normal output does.
+
+ * "git stash" learned the "--staged" option to stash away what has
+   been added to the index (and nothing else).
+
+ * "git var GIT_DEFAULT_BRANCH" is a way to see what name is used for
+   the newly created branch if "git init" is run.
+
+ * Various operating modes of "git reset" have been made to work
+   better with the sparse index.
+
+ * "git submodule deinit" for a submodule whose .git metadata
+   directory is embedded in its working tree refused to work, until
+   the submodule gets converted to use the "absorbed" form where the
+   metadata directory is stored in superproject, and a gitfile at the
+   top-level of the working tree of the submodule points at it.  The
+   command is taught to convert such submodules to the absorbed form
+   as needed.
+
+ * The completion script (in contrib/) learns that the "--date"
+   option of commands from the "git log" family takes "human" and
+   "auto" as valid values.
+
+ * "Zealous diff3" style of merge conflict presentation has been added.
+
+ * The "git log --format=%(describe)" placeholder has been extended to
+   allow passing selected command-line options to the underlying "git
+   describe" command.
+
+ * "default" and "reset" have been added to our color palette.
+
+ * The cryptographic signing using ssh keys can specify literal keys
+   for keytypes whose name do not begin with the "ssh-" prefix by
+   using the "key::" prefix mechanism (e.g. "key::ecdsa-sha2-nistp256").
+
+ * "git fetch" without the "--update-head-ok" option ought to protect
+   a checked out branch from getting updated, to prevent the working
+   tree that checks it out to go out of sync.  The code was written
+   before the use of "git worktree" got widespread, and only checked
+   the branch that was checked out in the current worktree, which has
+   been updated.
+
+ * "git name-rev" has been tweaked to give output that is shorter and
+   easier to understand.
+
+ * "git apply" has been taught to ignore a message without a patch
+   with the "--allow-empty" option.  It also learned to honor the
+   "--quiet" option given from the command line.
+
+ * The "init" and "set" subcommands in "git sparse-checkout" have been
+   unified for a better user experience and performance.
+
+ * Many git commands that deal with working tree files try to remove a
+   directory that becomes empty (i.e. "git switch" from a branch that
+   has the directory to another branch that does not would attempt
+   remove all files in the directory and the directory itself).  This
+   drops users into an unfamiliar situation if the command was run in
+   a subdirectory that becomes subject to removal due to the command.
+   The commands have been taught to keep an empty directory if it is
+   the directory they were started in to avoid surprising users.
+
+ * "git am" learns "--empty=(stop|drop|keep)" option to tweak what is
+   done to a piece of e-mail without a patch in it.
+
+ * The default merge message prepared by "git merge" records the name
+   of the current branch; the name can be overridden with a new option
+   to allow users to pretend a merge is made on a different branch.
+
+ * The way "git p4" shows file sizes in its output has been updated to
+   use human-readable units.
+
+ * "git -c branch.autosetupmerge=inherit branch new old" makes "new"
+   to have the same upstream as the "old" branch, instead of marking
+   "old" itself as its upstream.
+
+
+Performance, Internal Implementation, Development Support etc.
+
+ * The use of errno as a means to carry the nature of error in the ref
+   API implementation has been reworked and reduced.
+
+ * Teach and encourage first-time contributors to this project to
+   state the base commit when they submit their topic.
+
+ * The command line completion for "git send-email" options have been
+   tweaked to make it easier to keep it in sync with the command itself.
+
+ * Ensure that the sparseness of the in-core index matches the
+   index.sparse configuration specified by the repository immediately
+   after the on-disk index file is read.
+
+ * Code clean-up to eventually allow information on remotes defined
+   for an arbitrary repository to be read.
+
+ * Build optimization.
+
+ * Tighten code for testing pack-bitmap.
+
+ * Weather balloon to break people with compilers that do not support
+   C99.
+
+ * The "reftable" backend for the refs API, without integrating into
+   the refs subsystem, has been added.
+
+ * More tests are marked as leak-free.
+
+ * The test framework learns to list unsatisfied test prerequisites,
+   and optionally error out when prerequisites that are expected to be
+   satisfied are not.
+
+ * The default setting for trace2 event nesting was too low to cause
+   test failures, which is worked around by bumping it up in the test
+   framework.
+
+ * Drop support for TravisCI and update test workflows at GitHub.
+
+ * Many tests that used to need GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+   mechanism to force "git" to use 'master' as the default name for
+   the initial branch no longer need it; the use of the mechanism from
+   them have been removed.
+
+ * Allow running our tests while disabling fsync.
+
+ * Document the parameters given to the reflog entry iterator callback
+   functions.
+   (merge e6e94f34b2 jc/reflog-iterator-callback-doc later to maint).
+
+ * The test helper for refs subsystem learned to write bogus and/or
+   nonexistent object name to refs to simulate error situations we
+   want to test Git in.
+
+ * "diff --histogram" optimization.
+
+ * Weather balloon to find compilers that do not grok variable
+   declaration in the for() loop.
+
+ * diff and blame commands have been taught to work better with sparse
+   index.
+
+ * The chainlint test script linter in the test suite has been updated.
+
+ * The DEVELOPER=yes build uses -std=gnu99 now.
+
+ * "git format-patch" uses a single rev_info instance and then exits.
+   Mark the structure with UNLEAK() macro to squelch leak sanitizer.
+
+ * New interface into the tmp-objdir API to help in-core use of the
+   quarantine feature.
+
+ * Broken &&-chains in the test scripts have been corrected.
+
+ * The RCS keyword substitution in "git p4" used to be done assuming
+   that the contents are UTF-8 text, which can trigger decoding
+   errors.  We now treat the contents as a bytestring for robustness
+   and correctness.
+
+ * The conditions to choose different definitions of the FLEX_ARRAY
+   macro for vendor compilers has been simplified to make it easier to
+   maintain.
+
+ * Correctness and performance update to "diff --color-moved" feature.
+
+ * "git upload-pack" (the other side of "git fetch") used a 8kB buffer
+   but most of its payload came on 64kB "packets".  The buffer size
+   has been enlarged so that such a packet fits.
+
+ * "git fetch" and "git pull" are now declared sparse-index clean.
+   Also "git ls-files" learns the "--sparse" option to help debugging.
+
+ * Similar message templates have been consolidated so that
+   translators need to work on fewer number of messages.
+
+
+Fixes since v2.34
+-----------------
+
+ * "git grep" looking in a blob that has non-UTF8 payload was
+   completely broken when linked with certain versions of PCREv2
+   library in the latest release.
+
+ * Other code cleanup, docfix, build fix, etc.
+
+ * "git pull" with any strategy when the other side is behind us
+   should succeed as it is a no-op, but doesn't.
+
+ * An earlier change in 2.34.0 caused JGit application (that abused
+   GIT_EDITOR mechanism when invoking "git config") to get stuck with
+   a SIGTTOU signal; it has been reverted.
+
+ * An earlier change that broke .gitignore matching has been reverted.
+
+ * Things like "git -c branch.sort=bogus branch new HEAD", i.e. the
+   operation modes of the "git branch" command that do not need the
+   sort key information, no longer errors out by seeing a bogus sort
+   key.
+   (merge 98e7ab6d42 jc/fix-ref-sorting-parse later to maint).
+
+ * The compatibility implementation for unsetenv(3) were written to
+   mimic ancient, non-POSIX, variant seen in an old glibc; it has been
+   changed to return an integer to match the more modern era.
+   (merge a38989bd5b jc/unsetenv-returns-an-int later to maint).
+
+ * The clean/smudge conversion code path has been prepared to better
+   work on platforms where ulong is narrower than size_t.
+   (merge 596b5e77c9 mc/clean-smudge-with-llp64 later to maint).
+
+ * Redact the path part of packfile URI that appears in the trace output.
+   (merge 0ba558ffb1 if/redact-packfile-uri later to maint).
+
+ * CI has been taught to catch some Unicode directional formatting
+   sequence that can be used in certain mischief.
+   (merge 0e7696c64d js/ci-no-directional-formatting later to maint).
+
+ * The "--date=format:<strftime>" gained a workaround for the lack of
+   system support for a non-local timezone to handle "%s" placeholder.
+   (merge 9b591b9403 jk/strbuf-addftime-seconds-since-epoch later to maint).
+
+ * The "merge" subcommand of "git jump" (in contrib/) silently ignored
+   pathspec and other parameters.
+   (merge 67ba13e5a4 jk/jump-merge-with-pathspec later to maint).
+
+ * The code to decode the length of packed object size has been
+   corrected.
+   (merge 34de5b8eac jt/pack-header-lshift-overflow later to maint).
+
+ * The advice message given by "git pull" when the user hasn't made a
+   choice between merge and rebase still said that the merge is the
+   default, which no longer is the case.  This has been corrected.
+   (merge 71076d0edd ah/advice-pull-has-no-preference-between-rebase-and-merge later to maint).
+
+ * "git fetch", when received a bad packfile, can fail with SIGPIPE.
+   This wasn't wrong per-se, but we now detect the situation and fail
+   in a more predictable way.
+   (merge 2a4aed42ec jk/fetch-pack-avoid-sigpipe-to-index-pack later to maint).
+
+ * The function to cull a child process and determine the exit status
+   had two separate code paths for normal callers and callers in a
+   signal handler, and the latter did not yield correct value when the
+   child has caught a signal.  The handling of the exit status has
+   been unified for these two code paths.  An existing test with
+   flakiness has also been corrected.
+   (merge 5263e22cba jk/t7006-sigpipe-tests-fix later to maint).
+
+ * When a non-existent program is given as the pager, we tried to
+   reuse an uninitialized child_process structure and crashed, which
+   has been fixed.
+   (merge f917f57f40 em/missing-pager later to maint).
+
+ * The single-key-input mode in "git add -p" had some code to handle
+   keys that generate a sequence of input via ReadKey(), which did not
+   handle end-of-file correctly, which has been fixed.
+   (merge fc8a8126df cb/add-p-single-key-fix later to maint).
+
+ * "git rebase -x" added an unnecessary 'exec' instructions before
+   'noop', which has been corrected.
+   (merge cc9dcdee61 en/rebase-x-fix later to maint).
+
+ * When the "git push" command is killed while the receiving end is
+   trying to report what happened to the ref update proposals, the
+   latter used to die, due to SIGPIPE.  The code now ignores SIGPIPE
+   to increase our chances to run the post-receive hook after it
+   happens.
+   (merge d34182b9e3 rj/receive-pack-avoid-sigpipe-during-status-reporting later to maint).
+
+ * "git worktree add" showed "Preparing worktree" message to the
+   standard output stream, but when it failed, the message from die()
+   went to the standard error stream.  Depending on the order the
+   stdio streams are flushed at the program end, this resulted in
+   confusing output.  It has been corrected by sending all the chatty
+   messages to the standard error stream.
+   (merge b50252484f es/worktree-chatty-to-stderr later to maint).
+
+ * Coding guideline document has been updated to clarify what goes to
+   standard error in our system.
+   (merge e258eb4800 es/doc-stdout-vs-stderr later to maint).
+
+ * The sparse-index/sparse-checkout feature had a bug in its use of
+   the matching code to determine which path is in or outside the
+   sparse checkout patterns.
+   (merge 8c5de0d265 ds/sparse-deep-pattern-checkout-fix later to maint).
+
+ * "git rebase -x" by mistake started exporting the GIT_DIR and
+   GIT_WORK_TREE environment variables when the command was rewritten
+   in C, which has been corrected.
+   (merge 434e0636db en/rebase-x-wo-git-dir-env later to maint).
+
+ * When "git log" implicitly enabled the "decoration" processing
+   without being explicitly asked with "--decorate" option, it failed
+   to read and honor the settings given by the "--decorate-refs"
+   option.
+
+ * "git fetch --set-upstream" did not check if there is a current
+   branch, leading to a segfault when it is run on a detached HEAD,
+   which has been corrected.
+   (merge 17baeaf82d ab/fetch-set-upstream-while-detached later to maint).
+
+ * Among some code paths that ask an yes/no question, only one place
+   gave a prompt that looked different from the others, which has been
+   updated to match what the others create.
+   (merge 0fc8ed154c km/help-prompt-fix later to maint).
+
+ * "git log --invert-grep --author=<name>" used to exclude commits
+   written by the given author, but now "--invert-grep" only affects
+   the matches made by the "--grep=<pattern>" option.
+   (merge 794c000267 rs/log-invert-grep-with-headers later to maint).
+
+ * "git grep --perl-regexp" failed to match UTF-8 characters with
+   wildcard when the pattern consists only of ASCII letters, which has
+   been corrected.
+   (merge 32e3e8bc55 rs/pcre2-utf later to maint).
+
+ * Certain sparse-checkout patterns that are valid in non-cone mode
+   led to segfault in cone mode, which has been corrected.
+
+ * Use of certain "git rev-list" options with "git fast-export"
+   created nonsense results (the worst two of which being "--reverse"
+   and "--invert-grep --grep=<foo>").  The use of "--first-parent" is
+   made to behave a bit more sensible than before.
+   (merge 726a228dfb ws/fast-export-with-revision-options later to maint).
+
+ * Perf tests were run with end-user's shell, but it has been
+   corrected to use the shell specified by $TEST_SHELL_PATH.
+   (merge 9ccab75608 ja/perf-use-specified-shell later to maint).
+
+ * Fix dependency rules to generate hook-list.h header file.
+   (merge d3fd1a6667 ab/makefile-hook-list-dependency-fix later to maint).
+
+ * "git stash" by default triggers its "push" action, but its
+   implementation also made "git stash -h" to show short help only for
+   "git stash push", which has been corrected.
+   (merge ca7990cea5 ab/do-not-limit-stash-help-to-push later to maint).
+
+ * "git apply --3way" bypasses the attempt to do a three-way
+   application in more cases to address the regression caused by the
+   recent change to use direct application as a fallback.
+   (merge 34d607032c jz/apply-3-corner-cases later to maint).
+
+ * Fix performance-releated bug in "git subtree" (in contrib/).
+   (merge 3ce8888fb4 jl/subtree-check-parents-argument-passing-fix later to maint).
+
+ * Extend the guidance to choose the base commit to build your work
+   on, and hint/nudge contributors to read others' changes.
+   (merge fdfae830f8 jc/doc-submitting-patches-choice-of-base later to maint).
+
+ * A corner case bug in the ort merge strategy has been corrected.
+   (merge d30126c20d en/merge-ort-renorm-with-rename-delete-conflict-fix later to maint).
+
+ * "git stash apply" forgot to attempt restoring untracked files when
+   it failed to restore changes to tracked ones.
+   (merge 71cade5a0b en/stash-df-fix later to maint).
+
+ * Calling dynamically loaded functions on Windows has been corrected.
+   (merge 4a9b204920 ma/windows-dynload-fix later to maint).
+
+ * Some lockfile code called free() in signal-death code path, which
+   has been corrected.
+   (merge 58d4d7f1c5 ps/lockfile-cleanup-fix later to maint).
+
+ * Other code cleanup, docfix, build fix, etc.
+   (merge 74db416c9c cw/protocol-v2-doc-fix later to maint).
+   (merge f9b2b6684d ja/doc-cleanup later to maint).
+   (merge 7d1b866778 jc/fix-first-object-walk later to maint).
+   (merge 538ac74604 js/trace2-avoid-recursive-errors later to maint).
+   (merge 152923b132 jk/t5319-midx-corruption-test-deflake later to maint).
+   (merge 9081a421a6 ab/checkout-branch-info-leakfix later to maint).
+   (merge 42c456ff81 rs/mergesort later to maint).
+   (merge ad506e6780 tl/midx-docfix later to maint).
+   (merge bf5b83fd8a hk/ci-checkwhitespace-commentfix later to maint).
+   (merge 49f1eb3b34 jk/refs-g11-workaround later to maint).
+   (merge 7d3fc7df70 jt/midx-doc-fix later to maint).
+   (merge 7b089120d9 hn/create-reflog-simplify later to maint).
+   (merge 9e12400da8 cb/mingw-gmtime-r later to maint).
+   (merge 0bf0de6cc7 tb/pack-revindex-on-disk-cleanup later to maint).
+   (merge 2c68f577fc ew/cbtree-remove-unused-and-broken-cb-unlink later to maint).
+   (merge eafd6e7e55 ab/die-with-bug later to maint).
+   (merge 91028f7659 jc/grep-patterntype-default-doc later to maint).
+   (merge 47ca93d071 ds/repack-fixlets later to maint).
+   (merge e6a9bc0c60 rs/t4202-invert-grep-test-fix later to maint).
+   (merge deb5407a42 gh/gpg-doc-markup-fix later to maint).
+   (merge 999bba3e0b rs/daemon-plug-leak later to maint).
+   (merge 786eb1ba39 js/l10n-mention-ngettext-early-in-readme later to maint).
+   (merge 2f12b31b74 ab/makefile-msgfmt-wo-stats later to maint).
+   (merge 0517f591ca fs/gpg-unknown-key-test-fix later to maint).
+   (merge 97d6fb5a1f ma/header-dup-cleanup later to maint).
diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches
index 11e0305..92b80d9 100644
--- a/Documentation/SubmittingPatches
+++ b/Documentation/SubmittingPatches
@@ -19,8 +19,10 @@
   base your work on the tip of the topic.
 
 * A new feature should be based on `master` in general. If the new
-  feature depends on a topic that is in `seen`, but not in `master`,
-  base your work on the tip of that topic.
+  feature depends on other topics that are in `next`, but not in
+  `master`, fork a branch from the tip of `master`, merge these topics
+  to the branch, and work on that branch.  You can remind yourself of
+  how you prepared the base with `git log --first-parent master..`.
 
 * Corrections and enhancements to a topic not yet in `master` should
   be based on the tip of that topic. If the topic has not been merged
@@ -28,10 +30,10 @@
   into the series.
 
 * In the exceptional case that a new feature depends on several topics
-  not in `master`, start working on `next` or `seen` privately and send
-  out patches for discussion. Before the final merge, you may have to
-  wait until some of the dependent topics graduate to `master`, and
-  rebase your work.
+  not in `master`, start working on `next` or `seen` privately and
+  send out patches only for discussion. Once your new feature starts
+  to stabilize, you would have to rebase it (see the "depends on other
+  topics" above).
 
 * Some parts of the system have dedicated maintainers with their own
   repositories (see the section "Subsystems" below).  Changes to
@@ -71,8 +73,13 @@
 [[tests]]
 When adding a new feature, make sure that you have new tests to show
 the feature triggers the new behavior when it should, and to show the
-feature does not trigger when it shouldn't.  After any code change, make
-sure that the entire test suite passes.
+feature does not trigger when it shouldn't.  After any code change,
+make sure that the entire test suite passes.  When fixing a bug, make
+sure you have new tests that break if somebody else breaks what you
+fixed by accident to avoid regression.  Also, try merging your work to
+'next' and 'seen' and make sure the tests still pass; topics by others
+that are still in flight may have unexpected interactions with what
+you are trying to do in your topic.
 
 Pushing to a fork of https://github.com/git/git will use their CI
 integration to test your changes on Linux, Mac and Windows. See the
@@ -144,8 +151,21 @@
 archive, summarize the relevant points of the discussion.
 
 [[commit-reference]]
-If you want to reference a previous commit in the history of a stable
-branch, use the format "abbreviated hash (subject, date)", like this:
+
+There are a few reasons why you may want to refer to another commit in
+the "more stable" part of the history (i.e. on branches like `maint`,
+`master`, and `next`):
+
+. A commit that introduced the root cause of a bug you are fixing.
+
+. A commit that introduced a feature that you are enhancing.
+
+. A commit that conflicts with your work when you made a trial merge
+  of your work into `next` and `seen` for testing.
+
+When you reference a commit on a more stable branch (like `master`,
+`maint` and `next`), use the format "abbreviated hash (subject,
+date)", like this:
 
 ....
 	Commit f86a374 (pack-bitmap.c: fix a memleak, 2015-03-30)
@@ -259,9 +279,11 @@
 or include any extra files which do not relate to what your patch
 is trying to achieve. Make sure to review
 your patch after generating it, to ensure accuracy.  Before
-sending out, please make sure it cleanly applies to the `master`
-branch head.  If you are preparing a work based on "next" branch,
-that is fine, but please mark it as such.
+sending out, please make sure it cleanly applies to the base you
+have chosen in the "Decide what to base your work on" section,
+and unless it targets the `master` branch (which is the default),
+mark your patches as such.
+
 
 [[send-patches]]
 === Sending your patches.
@@ -365,7 +387,10 @@
 Send your patch with "To:" set to the mailing list, with "cc:" listing
 people who are involved in the area you are touching (the `git
 contacts` command in `contrib/contacts/` can help to
-identify them), to solicit comments and reviews.
+identify them), to solicit comments and reviews.  Also, when you made
+trial merges of your topic to `next` and `seen`, you may have noticed
+work by others conflicting with your changes.  There is a good possibility
+that these people may know the area you are touching well.
 
 :current-maintainer: footnote:[The current maintainer: gitster@pobox.com]
 :git-ml: footnote:[The mailing list: git@vger.kernel.org]
diff --git a/Documentation/config.txt b/Documentation/config.txt
index 1167e88..b168f02 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -262,11 +262,19 @@
        colors (at most two, one for foreground and one for background)
        and attributes (as many as you want), separated by spaces.
 +
-The basic colors accepted are `normal`, `black`, `red`, `green`, `yellow`,
-`blue`, `magenta`, `cyan` and `white`.  The first color given is the
-foreground; the second is the background.  All the basic colors except
-`normal` have a bright variant that can be specified by prefixing the
-color with `bright`, like `brightred`.
+The basic colors accepted are `normal`, `black`, `red`, `green`,
+`yellow`, `blue`, `magenta`, `cyan`, `white` and `default`.  The first
+color given is the foreground; the second is the background.  All the
+basic colors except `normal` and `default` have a bright variant that can
+be specified by prefixing the color with `bright`, like `brightred`.
++
+The color `normal` makes no change to the color. It is the same as an
+empty string, but can be used as the foreground color when specifying a
+background color alone (for example, "normal red").
++
+The color `default` explicitly resets the color to the terminal default,
+for example to specify a cleared background. Although it varies between
+terminals, this is usually not the same as setting to "white black".
 +
 Colors may also be given as numbers between 0 and 255; these use ANSI
 256-color mode (but note that not all terminals may support this).  If
@@ -280,6 +288,11 @@
 be turned off by prefixing them with `no` or `no-` (e.g., `noreverse`,
 `no-ul`, etc).
 +
+The pseudo-attribute `reset` resets all colors and attributes before
+applying the specified coloring. For example, `reset green` will result
+in a green foreground and default background without any active
+attributes.
++
 An empty color string produces no color effect at all. This can be used
 to avoid coloring specific elements without disabling color entirely.
 +
diff --git a/Documentation/config/branch.txt b/Documentation/config/branch.txt
index d323d73..1e0c7af 100644
--- a/Documentation/config/branch.txt
+++ b/Documentation/config/branch.txt
@@ -7,7 +7,8 @@
 	automatic setup is done; `true` -- automatic setup is done when the
 	starting point is a remote-tracking branch; `always` --
 	automatic setup is done when the starting point is either a
-	local branch or remote-tracking
+	local branch or remote-tracking branch; `inherit` -- if the starting point
+	has a tracking configuration, it is copied to the new
 	branch. This option defaults to true.
 
 branch.autoSetupRebase::
diff --git a/Documentation/config/gpg.txt b/Documentation/config/gpg.txt
index 4f30c7d..0cb189a 100644
--- a/Documentation/config/gpg.txt
+++ b/Documentation/config/gpg.txt
@@ -34,7 +34,7 @@
 * `fully`
 * `ultimate`
 
-gpg.ssh.defaultKeyCommand:
+gpg.ssh.defaultKeyCommand::
 	This command that will be run when user.signingkey is not set and a ssh
 	signature is requested. On successful exit a valid ssh public key is
 	expected in the	first line of its output. To automatically use the first
@@ -44,7 +44,7 @@
 	A file containing ssh public keys which you are willing to trust.
 	The file consists of one or more lines of principals followed by an ssh
 	public key.
-	e.g.: user1@example.com,user2@example.com ssh-rsa AAAAX1...
+	e.g.: `user1@example.com,user2@example.com ssh-rsa AAAAX1...`
 	See ssh-keygen(1) "ALLOWED SIGNERS" for details.
 	The principal is only used to identify the key and is available when
 	verifying a signature.
@@ -64,6 +64,11 @@
 in the repository itself using a path relative to the top-level of the working tree.
 This way only committers with an already valid key can add or change keys in the keyring.
 +
+Since OpensSSH 8.8 this file allows specifying a key lifetime using valid-after &
+valid-before options. Git will mark signatures as valid if the signing key was
+valid at the time of the signatures creation. This allows users to change a
+signing key without invalidating all previously made signatures.
++
 Using a SSH CA key with the cert-authority option
 (see ssh-keygen(1) "CERTIFICATES") is also valid.
 
diff --git a/Documentation/config/grep.txt b/Documentation/config/grep.txt
index 44abe45..182edd8 100644
--- a/Documentation/config/grep.txt
+++ b/Documentation/config/grep.txt
@@ -8,7 +8,8 @@
 	Set the default matching behavior. Using a value of 'basic', 'extended',
 	'fixed', or 'perl' will enable the `--basic-regexp`, `--extended-regexp`,
 	`--fixed-strings`, or `--perl-regexp` option accordingly, while the
-	value 'default' will return to the default matching behavior.
+	value 'default' will use the `grep.extendedRegexp` option to choose
+	between 'basic' and 'extended'.
 
 grep.extendedRegexp::
 	If set to true, enable `--extended-regexp` option by default. This
diff --git a/Documentation/config/merge.txt b/Documentation/config/merge.txt
index e27cc63..99e83dd 100644
--- a/Documentation/config/merge.txt
+++ b/Documentation/config/merge.txt
@@ -4,7 +4,14 @@
 	shows a `<<<<<<<` conflict marker, changes made by one side,
 	a `=======` marker, changes made by the other side, and then
 	a `>>>>>>>` marker.  An alternate style, "diff3", adds a `|||||||`
-	marker and the original text before the `=======` marker.
+	marker and the original text before the `=======` marker.  The
+	"merge" style tends to produce smaller conflict regions than diff3,
+	both because of the exclusion of the original text, and because
+	when a subset of lines match on the two sides they are just pulled
+	out of the conflict region.  Another alternate style, "zdiff3", is
+	similar to diff3 but removes matching lines on the two sides from
+	the conflict region when those matching lines appear near either
+	the beginning or end of a conflict region.
 
 merge.defaultToUpstream::
 	If merge is called without any commit argument, merge the upstream
diff --git a/Documentation/config/user.txt b/Documentation/config/user.txt
index ad78dce..ec9233b 100644
--- a/Documentation/config/user.txt
+++ b/Documentation/config/user.txt
@@ -36,10 +36,13 @@
 	commit, you can override the default selection with this variable.
 	This option is passed unchanged to gpg's --local-user parameter,
 	so you may specify a key using any method that gpg supports.
-	If gpg.format is set to "ssh" this can contain the literal ssh public
-	key (e.g.: "ssh-rsa XXXXXX identifier") or a file which contains it and
-	corresponds to the private key used for signing. The private key
-	needs to be available via ssh-agent. Alternatively it can be set to
-	a file containing a private key directly. If not set git will call
-	gpg.ssh.defaultKeyCommand (e.g.: "ssh-add -L") and try to use the first
-	key available.
+	If gpg.format is set to `ssh` this can contain the path to either
+	your private ssh key or the public key when ssh-agent is used.
+	Alternatively it can contain a public key prefixed with `key::`
+	directly (e.g.: "key::ssh-rsa XXXXXX identifier"). The private key
+	needs to be available via ssh-agent. If not set git will call
+	gpg.ssh.defaultKeyCommand (e.g.: "ssh-add -L") and try to use the
+	first key available. For backward compatibility, a raw key which
+	begins with "ssh-", such as "ssh-rsa XXXXXX identifier", is treated
+	as "key::ssh-rsa XXXXXX identifier", but this form is deprecated;
+	use the `key::` form instead.
diff --git a/Documentation/date-formats.txt b/Documentation/date-formats.txt
index 99c455f..67645ca 100644
--- a/Documentation/date-formats.txt
+++ b/Documentation/date-formats.txt
@@ -5,9 +5,9 @@
 support the following date formats:
 
 Git internal format::
-	It is `<unix timestamp> <time zone offset>`, where `<unix
-	timestamp>` is the number of seconds since the UNIX epoch.
-	`<time zone offset>` is a positive or negative offset from UTC.
+	It is `<unix-timestamp> <time-zone-offset>`, where
+	`<unix-timestamp>` is the number of seconds since the UNIX epoch.
+	`<time-zone-offset>` is a positive or negative offset from UTC.
 	For example CET (which is 1 hour ahead of UTC) is `+0100`.
 
 RFC 2822::
diff --git a/Documentation/git-am.txt b/Documentation/git-am.txt
index 0a4a984..09107fb 100644
--- a/Documentation/git-am.txt
+++ b/Documentation/git-am.txt
@@ -16,8 +16,9 @@
 	 [--exclude=<path>] [--include=<path>] [--reject] [-q | --quiet]
 	 [--[no-]scissors] [-S[<keyid>]] [--patch-format=<format>]
 	 [--quoted-cr=<action>]
+	 [--empty=(stop|drop|keep)]
 	 [(<mbox> | <Maildir>)...]
-'git am' (--continue | --skip | --abort | --quit | --show-current-patch[=(diff|raw)])
+'git am' (--continue | --skip | --abort | --quit | --show-current-patch[=(diff|raw)] | --allow-empty)
 
 DESCRIPTION
 -----------
@@ -63,6 +64,14 @@
 --quoted-cr=<action>::
 	This flag will be passed down to 'git mailinfo' (see linkgit:git-mailinfo[1]).
 
+--empty=(stop|drop|keep)::
+	By default, or when the option is set to 'stop', the command
+	errors out on an input e-mail message lacking a patch
+	and stops into the middle of the current am session. When this
+	option is set to 'drop', skip such an e-mail message instead.
+	When this option is set to 'keep', create an empty commit,
+	recording the contents of the e-mail message as its log.
+
 -m::
 --message-id::
 	Pass the `-m` flag to 'git mailinfo' (see linkgit:git-mailinfo[1]),
@@ -191,6 +200,11 @@
 	the e-mail message; if `diff`, show the diff portion only.
 	Defaults to `raw`.
 
+--allow-empty::
+	After a patch failure on an input e-mail message lacking a patch,
+	create an empty commit with the contents of the e-mail message
+	as its log message.
+
 DISCUSSION
 ----------
 
diff --git a/Documentation/git-apply.txt b/Documentation/git-apply.txt
index aa1ae56..b6d77f4 100644
--- a/Documentation/git-apply.txt
+++ b/Documentation/git-apply.txt
@@ -16,7 +16,7 @@
 	  [--ignore-space-change | --ignore-whitespace]
 	  [--whitespace=(nowarn|warn|fix|error|error-all)]
 	  [--exclude=<path>] [--include=<path>] [--directory=<root>]
-	  [--verbose] [--unsafe-paths] [<patch>...]
+	  [--verbose | --quiet] [--unsafe-paths] [--allow-empty] [<patch>...]
 
 DESCRIPTION
 -----------
@@ -228,6 +228,11 @@
 	current patch being applied will be printed. This option will cause
 	additional information to be reported.
 
+-q::
+--quiet::
+	Suppress stderr output. Messages about patch status and progress
+	will not be printed.
+
 --recount::
 	Do not trust the line counts in the hunk headers, but infer them
 	by inspecting the patch (e.g. after editing the patch without
@@ -251,6 +256,10 @@
 the `--unsafe-paths` option to override this safety check.  This option
 has no effect when `--index` or `--cached` is in use.
 
+--allow-empty::
+	Don't return error for patches containing no diff. This includes
+	empty patches and patches with commit text only.
+
 CONFIGURATION
 -------------
 
diff --git a/Documentation/git-archimport.txt b/Documentation/git-archimport.txt
index a595a0f..847777f 100644
--- a/Documentation/git-archimport.txt
+++ b/Documentation/git-archimport.txt
@@ -9,14 +9,14 @@
 SYNOPSIS
 --------
 [verse]
-'git archimport' [-h] [-v] [-o] [-a] [-f] [-T] [-D depth] [-t tempdir]
-               <archive/branch>[:<git-branch>] ...
+'git archimport' [-h] [-v] [-o] [-a] [-f] [-T] [-D <depth>] [-t <tempdir>]
+	       <archive>/<branch>[:<git-branch>]...
 
 DESCRIPTION
 -----------
 Imports a project from one or more GNU Arch repositories.
 It will follow branches
-and repositories within the namespaces defined by the <archive/branch>
+and repositories within the namespaces defined by the <archive>/<branch>
 parameters supplied. If it cannot find the remote branch a merge comes from
 it will just import it as a regular commit. If it can find it, it will mark it
 as a merge whenever possible (see discussion below).
@@ -27,7 +27,7 @@
 
 It expects to be dealing with one project only. If it sees
 branches that have different roots, it will refuse to run. In that case,
-edit your <archive/branch> parameters to define clearly the scope of the
+edit your <archive>/<branch> parameters to define clearly the scope of the
 import.
 
 'git archimport' uses `tla` extensively in the background to access the
@@ -42,7 +42,7 @@
 
 While 'git archimport' will try to create sensible branch names for the
 archives that it imports, it is also possible to specify Git branch names
-manually.  To do so, write a Git branch name after each <archive/branch>
+manually.  To do so, write a Git branch name after each <archive>/<branch>
 parameter, separated by a colon.  This way, you can shorten the Arch
 branch names and convert Arch jargon to Git jargon, for example mapping a
 "PROJECT{litdd}devo{litdd}VERSION" branch to "master".
@@ -104,8 +104,8 @@
 	Override the default tempdir.
 
 
-<archive/branch>::
-	Archive/branch identifier in a format that `tla log` understands.
+<archive>/<branch>::
+	<archive>/<branch> identifier in a format that `tla log` understands.
 
 
 GIT
diff --git a/Documentation/git-branch.txt b/Documentation/git-branch.txt
index 8af42ef..2d52ae3 100644
--- a/Documentation/git-branch.txt
+++ b/Documentation/git-branch.txt
@@ -16,7 +16,7 @@
 	[--points-at <object>] [--format=<format>]
 	[(-r | --remotes) | (-a | --all)]
 	[--list] [<pattern>...]
-'git branch' [--track | --no-track] [-f] <branchname> [<start-point>]
+'git branch' [--track [direct|inherit] | --no-track] [-f] <branchname> [<start-point>]
 'git branch' (--set-upstream-to=<upstream> | -u <upstream>) [<branchname>]
 'git branch' --unset-upstream [<branchname>]
 'git branch' (-m | -M) [<oldbranch>] <newbranch>
@@ -206,24 +206,34 @@
 	Display the full sha1s in the output listing rather than abbreviating them.
 
 -t::
---track::
+--track [inherit|direct]::
 	When creating a new branch, set up `branch.<name>.remote` and
-	`branch.<name>.merge` configuration entries to mark the
-	start-point branch as "upstream" from the new branch. This
+	`branch.<name>.merge` configuration entries to set "upstream" tracking
+	configuration for the new branch. This
 	configuration will tell git to show the relationship between the
 	two branches in `git status` and `git branch -v`. Furthermore,
 	it directs `git pull` without arguments to pull from the
 	upstream when the new branch is checked out.
 +
-This behavior is the default when the start point is a remote-tracking branch.
+The exact upstream branch is chosen depending on the optional argument:
+`--track` or `--track direct` means to use the start-point branch itself as the
+upstream; `--track inherit` means to copy the upstream configuration of the
+start-point branch.
++
+`--track direct` is the default when the start point is a remote-tracking branch.
 Set the branch.autoSetupMerge configuration variable to `false` if you
 want `git switch`, `git checkout` and `git branch` to always behave as if `--no-track`
 were given. Set it to `always` if you want this behavior when the
-start-point is either a local or remote-tracking branch.
+start-point is either a local or remote-tracking branch. Set it to
+`inherit` if you want to copy the tracking configuration from the
+branch point.
++
+See linkgit:git-pull[1] and linkgit:git-config[1] for additional discussion on
+how the `branch.<name>.remote` and `branch.<name>.merge` options are used.
 
 --no-track::
 	Do not set up "upstream" configuration, even if the
-	branch.autoSetupMerge configuration variable is true.
+	branch.autoSetupMerge configuration variable is set.
 
 --set-upstream::
 	As this option had confusing syntax, it is no longer supported.
diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index d473c9b..2a90ea6 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -11,7 +11,7 @@
 'git checkout' [-q] [-f] [-m] [<branch>]
 'git checkout' [-q] [-f] [-m] --detach [<branch>]
 'git checkout' [-q] [-f] [-m] [--detach] <commit>
-'git checkout' [-q] [-f] [-m] [[-b|-B|--orphan] <new_branch>] [<start_point>]
+'git checkout' [-q] [-f] [-m] [[-b|-B|--orphan] <new-branch>] [<start-point>]
 'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <pathspec>...
 'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] --pathspec-from-file=<file> [--pathspec-file-nul]
 'git checkout' (-p|--patch) [<tree-ish>] [--] [<pathspec>...]
@@ -43,7 +43,7 @@
 rather expensive side-effects to show only the tracking information,
 if exists, for the current branch.
 
-'git checkout' -b|-B <new_branch> [<start point>]::
+'git checkout' -b|-B <new-branch> [<start-point>]::
 
 	Specifying `-b` causes a new branch to be created as if
 	linkgit:git-branch[1] were called and then checked out.  In
@@ -52,11 +52,11 @@
 	`--track` without `-b` implies branch creation; see the
 	description of `--track` below.
 +
-If `-B` is given, `<new_branch>` is created if it doesn't exist; otherwise, it
+If `-B` is given, `<new-branch>` is created if it doesn't exist; otherwise, it
 is reset. This is the transactional equivalent of
 +
 ------------
-$ git branch -f <branch> [<start point>]
+$ git branch -f <branch> [<start-point>]
 $ git checkout <branch>
 ------------
 +
@@ -145,18 +145,18 @@
 on your side branch as `theirs` (i.e. "one contributor's work on top
 of it").
 
--b <new_branch>::
-	Create a new branch named `<new_branch>` and start it at
-	`<start_point>`; see linkgit:git-branch[1] for details.
+-b <new-branch>::
+	Create a new branch named `<new-branch>` and start it at
+	`<start-point>`; see linkgit:git-branch[1] for details.
 
--B <new_branch>::
-	Creates the branch `<new_branch>` and start it at `<start_point>`;
-	if it already exists, then reset it to `<start_point>`. This is
+-B <new-branch>::
+	Creates the branch `<new-branch>` and start it at `<start-point>`;
+	if it already exists, then reset it to `<start-point>`. This is
 	equivalent to running "git branch" with "-f"; see
 	linkgit:git-branch[1] for details.
 
 -t::
---track::
+--track [direct|inherit]::
 	When creating a new branch, set up "upstream" configuration. See
 	"--track" in linkgit:git-branch[1] for details.
 +
@@ -210,16 +210,16 @@
 	`<commit>` is not a branch name.  See the "DETACHED HEAD" section
 	below for details.
 
---orphan <new_branch>::
-	Create a new 'orphan' branch, named `<new_branch>`, started from
-	`<start_point>` and switch to it.  The first commit made on this
+--orphan <new-branch>::
+	Create a new 'orphan' branch, named `<new-branch>`, started from
+	`<start-point>` and switch to it.  The first commit made on this
 	new branch will have no parents and it will be the root of a new
 	history totally disconnected from all the other branches and
 	commits.
 +
 The index and the working tree are adjusted as if you had previously run
-`git checkout <start_point>`.  This allows you to start a new history
-that records a set of paths similar to `<start_point>` by easily running
+`git checkout <start-point>`.  This allows you to start a new history
+that records a set of paths similar to `<start-point>` by easily running
 `git commit -a` to make the root commit.
 +
 This can be useful when you want to publish the tree from a commit
@@ -229,7 +229,7 @@
 code.
 +
 If you want to start a disconnected history that records a set of paths
-that is totally different from the one of `<start_point>`, then you should
+that is totally different from the one of `<start-point>`, then you should
 clear the index and the working tree right after creating the orphan
 branch by running `git rm -rf .` from the top level of the working tree.
 Afterwards you will be ready to prepare your new files, repopulating the
@@ -266,8 +266,7 @@
 	The same as `--merge` option above, but changes the way the
 	conflicting hunks are presented, overriding the
 	`merge.conflictStyle` configuration variable.  Possible values are
-	"merge" (default) and "diff3" (in addition to what is shown by
-	"merge" style, shows the original contents).
+	"merge" (default), "diff3", and "zdiff3".
 
 -p::
 --patch::
@@ -341,10 +340,10 @@
 merge base of `A` and `B` if there is exactly one merge base. You can
 leave out at most one of `A` and `B`, in which case it defaults to `HEAD`.
 
-<new_branch>::
+<new-branch>::
 	Name for the new branch.
 
-<start_point>::
+<start-point>::
 	The name of a commit at which to start the new branch; see
 	linkgit:git-branch[1] for details. Defaults to `HEAD`.
 +
diff --git a/Documentation/git-cherry-pick.txt b/Documentation/git-cherry-pick.txt
index 5d75031..78dcc91 100644
--- a/Documentation/git-cherry-pick.txt
+++ b/Documentation/git-cherry-pick.txt
@@ -8,7 +8,7 @@
 SYNOPSIS
 --------
 [verse]
-'git cherry-pick' [--edit] [-n] [-m parent-number] [-s] [-x] [--ff]
+'git cherry-pick' [--edit] [-n] [-m <parent-number>] [-s] [-x] [--ff]
 		  [-S[<keyid>]] <commit>...
 'git cherry-pick' (--continue | --skip | --abort | --quit)
 
@@ -81,8 +81,8 @@
 	described above, and `-r` was to disable it.  Now the
 	default is not to do `-x` so this option is a no-op.
 
--m parent-number::
---mainline parent-number::
+-m <parent-number>::
+--mainline <parent-number>::
 	Usually you cannot cherry-pick a merge because you do not know which
 	side of the merge should be considered the mainline.  This
 	option specifies the parent number (starting from 1) of
diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt
index 3fe3810..984d194 100644
--- a/Documentation/git-clone.txt
+++ b/Documentation/git-clone.txt
@@ -9,10 +9,10 @@
 SYNOPSIS
 --------
 [verse]
-'git clone' [--template=<template_directory>]
+'git clone' [--template=<template-directory>]
 	  [-l] [-s] [--no-hardlinks] [-q] [-n] [--bare] [--mirror]
 	  [-o <name>] [-b <name>] [-u <upload-pack>] [--reference <repository>]
-	  [--dissociate] [--separate-git-dir <git dir>]
+	  [--dissociate] [--separate-git-dir <git-dir>]
 	  [--depth <depth>] [--[no-]single-branch] [--no-tags]
 	  [--recurse-submodules[=<pathspec>]] [--[no-]shallow-submodules]
 	  [--[no-]remote-submodules] [--jobs <n>] [--sparse] [--[no-]reject-shallow]
@@ -167,10 +167,10 @@
 	configuration variables are created.
 
 --sparse::
-	Initialize the sparse-checkout file so the working
-	directory starts with only the files in the root
-	of the repository. The sparse-checkout file can be
-	modified to grow the working directory as needed.
+	Employ a sparse-checkout, with only files in the toplevel
+	directory initially being present.  The
+	linkgit:git-sparse-checkout[1] command can be used to grow the
+	working directory as needed.
 
 --filter=<filter-spec>::
 	Use the partial clone feature and request that the server sends
@@ -211,7 +211,7 @@
 	via ssh, this specifies a non-default path for the command
 	run on the other end.
 
---template=<template_directory>::
+--template=<template-directory>::
 	Specify the directory from which templates will be used;
 	(See the "TEMPLATE DIRECTORY" section of linkgit:git-init[1].)
 
@@ -294,7 +294,7 @@
 	superproject's recorded SHA-1. Equivalent to passing `--remote` to
 	`git submodule update`.
 
---separate-git-dir=<git dir>::
+--separate-git-dir=<git-dir>::
 	Instead of placing the cloned repository where it is supposed
 	to be, place the cloned repository at the specified directory,
 	then make a filesystem-agnostic Git symbolic link to there.
diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
index 992225f..2285eff 100644
--- a/Documentation/git-config.txt
+++ b/Documentation/git-config.txt
@@ -9,20 +9,20 @@
 SYNOPSIS
 --------
 [verse]
-'git config' [<file-option>] [--type=<type>] [--fixed-value] [--show-origin] [--show-scope] [-z|--null] name [value [value-pattern]]
-'git config' [<file-option>] [--type=<type>] --add name value
-'git config' [<file-option>] [--type=<type>] [--fixed-value] --replace-all name value [value-pattern]
-'git config' [<file-option>] [--type=<type>] [--show-origin] [--show-scope] [-z|--null] [--fixed-value] --get name [value-pattern]
-'git config' [<file-option>] [--type=<type>] [--show-origin] [--show-scope] [-z|--null] [--fixed-value] --get-all name [value-pattern]
-'git config' [<file-option>] [--type=<type>] [--show-origin] [--show-scope] [-z|--null] [--fixed-value] [--name-only] --get-regexp name_regex [value-pattern]
-'git config' [<file-option>] [--type=<type>] [-z|--null] --get-urlmatch name URL
-'git config' [<file-option>] [--fixed-value] --unset name [value-pattern]
-'git config' [<file-option>] [--fixed-value] --unset-all name [value-pattern]
-'git config' [<file-option>] --rename-section old_name new_name
-'git config' [<file-option>] --remove-section name
+'git config' [<file-option>] [--type=<type>] [--fixed-value] [--show-origin] [--show-scope] [-z|--null] <name> [<value> [<value-pattern>]]
+'git config' [<file-option>] [--type=<type>] --add <name> <value>
+'git config' [<file-option>] [--type=<type>] [--fixed-value] --replace-all <name> <value> [<value-pattern>]
+'git config' [<file-option>] [--type=<type>] [--show-origin] [--show-scope] [-z|--null] [--fixed-value] --get <name> [<value-pattern>]
+'git config' [<file-option>] [--type=<type>] [--show-origin] [--show-scope] [-z|--null] [--fixed-value] --get-all <name> [<value-pattern>]
+'git config' [<file-option>] [--type=<type>] [--show-origin] [--show-scope] [-z|--null] [--fixed-value] [--name-only] --get-regexp <name-regex> [<value-pattern>]
+'git config' [<file-option>] [--type=<type>] [-z|--null] --get-urlmatch <name> <URL>
+'git config' [<file-option>] [--fixed-value] --unset <name> [<value-pattern>]
+'git config' [<file-option>] [--fixed-value] --unset-all <name> [<value-pattern>]
+'git config' [<file-option>] --rename-section <old-name> <new-name>
+'git config' [<file-option>] --remove-section <name>
 'git config' [<file-option>] [--show-origin] [--show-scope] [-z|--null] [--name-only] -l | --list
-'git config' [<file-option>] --get-color name [default]
-'git config' [<file-option>] --get-colorbool name [stdout-is-tty]
+'git config' [<file-option>] --get-color <name> [<default>]
+'git config' [<file-option>] --get-colorbool <name> [<stdout-is-tty>]
 'git config' [<file-option>] -e | --edit
 
 DESCRIPTION
@@ -102,9 +102,9 @@
 	in which section and variable names are lowercased, but subsection
 	names are not.
 
---get-urlmatch name URL::
+--get-urlmatch <name> <URL>::
 	When given a two-part name section.key, the value for
-	section.<url>.key whose <url> part matches the best to the
+	section.<URL>.key whose <URL> part matches the best to the
 	given URL is returned (if no such key exists, the value for
 	section.key is used as a fallback).  When given just the
 	section as name, do so for all the keys in the section and
@@ -145,8 +145,8 @@
 	read from or written to if `extensions.worktreeConfig` is
 	present. If not it's the same as `--local`.
 
--f config-file::
---file config-file::
+-f <config-file>::
+--file <config-file>::
 	For writing options: write to the specified file rather than the
 	repository `.git/config`.
 +
@@ -155,7 +155,7 @@
 +
 See also <<FILES>>.
 
---blob blob::
+--blob <blob>::
 	Similar to `--file` but use the given blob instead of a file. E.g.
 	you can use 'master:.gitmodules' to read values from the file
 	'.gitmodules' in the master branch. See "SPECIFYING REVISIONS"
@@ -246,18 +246,18 @@
 	all queried config options with the scope of that value
 	(local, global, system, command).
 
---get-colorbool name [stdout-is-tty]::
+--get-colorbool <name> [<stdout-is-tty>]::
 
-	Find the color setting for `name` (e.g. `color.diff`) and output
-	"true" or "false".  `stdout-is-tty` should be either "true" or
+	Find the color setting for `<name>` (e.g. `color.diff`) and output
+	"true" or "false".  `<stdout-is-tty>` should be either "true" or
 	"false", and is taken into account when configuration says
-	"auto".  If `stdout-is-tty` is missing, then checks the standard
+	"auto".  If `<stdout-is-tty>` is missing, then checks the standard
 	output of the command itself, and exits with status 0 if color
 	is to be used, or exits with status 1 otherwise.
 	When the color setting for `name` is undefined, the command uses
 	`color.ui` as fallback.
 
---get-color name [default]::
+--get-color <name> [<default>]::
 
 	Find the color configured for `name` (e.g. `color.diff.new`) and
 	output it as the ANSI color escape sequence to the standard
diff --git a/Documentation/git-credential.txt b/Documentation/git-credential.txt
index 206e3c5..f186730 100644
--- a/Documentation/git-credential.txt
+++ b/Documentation/git-credential.txt
@@ -8,7 +8,7 @@
 SYNOPSIS
 --------
 ------------------
-git credential <fill|approve|reject>
+'git credential' (fill|approve|reject)
 ------------------
 
 DESCRIPTION
diff --git a/Documentation/git-cvsexportcommit.txt b/Documentation/git-cvsexportcommit.txt
index 00154b6..41c8a8a 100644
--- a/Documentation/git-cvsexportcommit.txt
+++ b/Documentation/git-cvsexportcommit.txt
@@ -9,8 +9,8 @@
 SYNOPSIS
 --------
 [verse]
-'git cvsexportcommit' [-h] [-u] [-v] [-c] [-P] [-p] [-a] [-d cvsroot]
-	[-w cvsworkdir] [-W] [-f] [-m msgprefix] [PARENTCOMMIT] COMMITID
+'git cvsexportcommit' [-h] [-u] [-v] [-c] [-P] [-p] [-a] [-d <cvsroot>]
+	[-w <cvs-workdir>] [-W] [-f] [-m <msgprefix>] [<parent-commit>] <commit-id>
 
 
 DESCRIPTION
diff --git a/Documentation/git-cvsimport.txt b/Documentation/git-cvsimport.txt
index de1ebed..b3f2767 100644
--- a/Documentation/git-cvsimport.txt
+++ b/Documentation/git-cvsimport.txt
@@ -11,9 +11,9 @@
 [verse]
 'git cvsimport' [-o <branch-for-HEAD>] [-h] [-v] [-d <CVSROOT>]
 	      [-A <author-conv-file>] [-p <options-for-cvsps>] [-P <file>]
-	      [-C <git_repository>] [-z <fuzz>] [-i] [-k] [-u] [-s <subst>]
-	      [-a] [-m] [-M <regex>] [-S <regex>] [-L <commitlimit>]
-	      [-r <remote>] [-R] [<CVS_module>]
+	      [-C <git-repository>] [-z <fuzz>] [-i] [-k] [-u] [-s <subst>]
+	      [-a] [-m] [-M <regex>] [-S <regex>] [-L <commit-limit>]
+	      [-r <remote>] [-R] [<CVS-module>]
 
 
 DESCRIPTION
@@ -59,7 +59,7 @@
 	from `CVS/Root`. If no such file exists, it checks for the
 	`CVSROOT` environment variable.
 
-<CVS_module>::
+<CVS-module>::
 	The CVS module you want to import. Relative to <CVSROOT>.
 	If not given, 'git cvsimport' tries to read it from
 	`CVS/Repository`.
diff --git a/Documentation/git-diff-files.txt b/Documentation/git-diff-files.txt
index 906774f..bf1febb 100644
--- a/Documentation/git-diff-files.txt
+++ b/Documentation/git-diff-files.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git diff-files' [-q] [-0|-1|-2|-3|-c|--cc] [<common diff options>] [<path>...]
+'git diff-files' [-q] [-0|-1|-2|-3|-c|--cc] [<common-diff-options>] [<path>...]
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-diff-index.txt b/Documentation/git-diff-index.txt
index 27acb31..679cae2 100644
--- a/Documentation/git-diff-index.txt
+++ b/Documentation/git-diff-index.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git diff-index' [-m] [--cached] [--merge-base] [<common diff options>] <tree-ish> [<path>...]
+'git diff-index' [-m] [--cached] [--merge-base] [<common-diff-options>] <tree-ish> [<path>...]
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-diff-tree.txt b/Documentation/git-diff-tree.txt
index 2fc24c5..274d5ea 100644
--- a/Documentation/git-diff-tree.txt
+++ b/Documentation/git-diff-tree.txt
@@ -11,7 +11,7 @@
 [verse]
 'git diff-tree' [--stdin] [-m] [-s] [-v] [--no-commit-id] [--pretty]
 	      [-t] [-r] [-c | --cc] [--combined-all-paths] [--root] [--merge-base]
-	      [<common diff options>] <tree-ish> [<tree-ish>] [<path>...]
+	      [<common-diff-options>] <tree-ish> [<tree-ish>] [<path>...]
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-fmt-merge-msg.txt b/Documentation/git-fmt-merge-msg.txt
index 6793d8f..6f28812 100644
--- a/Documentation/git-fmt-merge-msg.txt
+++ b/Documentation/git-fmt-merge-msg.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git fmt-merge-msg' [-m <message>] [--log[=<n>] | --no-log]
+'git fmt-merge-msg' [-m <message>] [--into-name <branch>] [--log[=<n>] | --no-log]
 'git fmt-merge-msg' [-m <message>] [--log[=<n>] | --no-log] -F <file>
 
 DESCRIPTION
@@ -44,6 +44,10 @@
 	Use <message> instead of the branch names for the first line
 	of the log message.  For use with `--log`.
 
+--into-name <branch>::
+	Prepare the merge message as if merging to the branch `<branch>`,
+	instead of the name of the real branch to which the merge is made.
+
 -F <file>::
 --file <file>::
 	Take the list of merged objects from <file> instead of
diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
index 113eabc..be797d7 100644
--- a/Documentation/git-format-patch.txt
+++ b/Documentation/git-format-patch.txt
@@ -18,7 +18,7 @@
 		   [-n | --numbered | -N | --no-numbered]
 		   [--start-number <n>] [--numbered-files]
 		   [--in-reply-to=<message id>] [--suffix=.<sfx>]
-		   [--ignore-if-in-upstream]
+		   [--ignore-if-in-upstream] [--always]
 		   [--cover-from-description=<mode>]
 		   [--rfc] [--subject-prefix=<subject prefix>]
 		   [(--reroll-count|-v) <n>]
@@ -192,6 +192,10 @@
 	patches being generated, and any patch that matches is
 	ignored.
 
+--always::
+	Include patches for commits that do not introduce any change,
+	which are omitted by default.
+
 --cover-from-description=<mode>::
 	Controls which parts of the cover letter will be automatically
 	populated using the branch's description.
diff --git a/Documentation/git-fsck.txt b/Documentation/git-fsck.txt
index bd59661..5088783 100644
--- a/Documentation/git-fsck.txt
+++ b/Documentation/git-fsck.txt
@@ -12,7 +12,7 @@
 'git fsck' [--tags] [--root] [--unreachable] [--cache] [--no-reflogs]
 	 [--[no-]full] [--strict] [--verbose] [--lost-found]
 	 [--[no-]dangling] [--[no-]progress] [--connectivity-only]
-	 [--[no-]name-objects] [<object>*]
+	 [--[no-]name-objects] [<object>...]
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-gui.txt b/Documentation/git-gui.txt
index c9d7e96..e8f3ccb 100644
--- a/Documentation/git-gui.txt
+++ b/Documentation/git-gui.txt
@@ -8,7 +8,7 @@
 SYNOPSIS
 --------
 [verse]
-'git gui' [<command>] [arguments]
+'git gui' [<command>] [<arguments>]
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-help.txt b/Documentation/git-help.txt
index 96d5f59..44ea63c 100644
--- a/Documentation/git-help.txt
+++ b/Documentation/git-help.txt
@@ -9,14 +9,14 @@
 --------
 [verse]
 'git help' [-a|--all [--[no-]verbose]]
-	   [[-i|--info] [-m|--man] [-w|--web]] [COMMAND|GUIDE]
+	   [[-i|--info] [-m|--man] [-w|--web]] [<command>|<guide>]
 'git help' [-g|--guides]
 'git help' [-c|--config]
 
 DESCRIPTION
 -----------
 
-With no options and no COMMAND or GUIDE given, the synopsis of the 'git'
+With no options and no '<command>' or '<guide>' given, the synopsis of the 'git'
 command and a list of the most commonly used Git commands are printed
 on the standard output.
 
@@ -33,7 +33,7 @@
 
 If an alias is given, git shows the definition of the alias on
 standard output. To get the manual page for the aliased command, use
-`git COMMAND --help`.
+`git <command> --help`.
 
 Note that `git --help ...` is identical to `git help ...` because the
 former is internally converted into the latter.
diff --git a/Documentation/git-http-fetch.txt b/Documentation/git-http-fetch.txt
index 9fa17b6..319062c 100644
--- a/Documentation/git-http-fetch.txt
+++ b/Documentation/git-http-fetch.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git http-fetch' [-c] [-t] [-a] [-d] [-v] [-w filename] [--recover] [--stdin | --packfile=<hash> | <commit>] <url>
+'git http-fetch' [-c] [-t] [-a] [-d] [-v] [-w <filename>] [--recover] [--stdin | --packfile=<hash> | <commit>] <URL>
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-http-push.txt b/Documentation/git-http-push.txt
index ea03a4e..7c6a6dd 100644
--- a/Documentation/git-http-push.txt
+++ b/Documentation/git-http-push.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git http-push' [--all] [--dry-run] [--force] [--verbose] <url> <ref> [<ref>...]
+'git http-push' [--all] [--dry-run] [--force] [--verbose] <URL> <ref> [<ref>...]
 
 DESCRIPTION
 -----------
@@ -63,16 +63,15 @@
 cannot have a colon in it).  A single pattern '<name>' is just a
 shorthand for '<name>:<name>'.
 
-Each pattern pair consists of the source side (before the colon)
-and the destination side (after the colon).  The ref to be
-pushed is determined by finding a match that matches the source
-side, and where it is pushed is determined by using the
-destination side.
+Each pattern pair '<src>:<dst>' consists of the source side (before
+the colon) and the destination side (after the colon).  The ref to be
+pushed is determined by finding a match that matches the source side,
+and where it is pushed is determined by using the destination side.
 
- - It is an error if <src> does not match exactly one of the
+ - It is an error if '<src>' does not match exactly one of the
    local refs.
 
- - If <dst> does not match any remote ref, either
+ - If '<dst>' does not match any remote ref, either
 
    * it has to start with "refs/"; <dst> is used as the
      destination literally in this case.
diff --git a/Documentation/git-init-db.txt b/Documentation/git-init-db.txt
index 648a6cd..18bf1a3 100644
--- a/Documentation/git-init-db.txt
+++ b/Documentation/git-init-db.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git init-db' [-q | --quiet] [--bare] [--template=<template_directory>] [--separate-git-dir <git dir>] [--shared[=<permissions>]]
+'git init-db' [-q | --quiet] [--bare] [--template=<template-directory>] [--separate-git-dir <git-dir>] [--shared[=<permissions>]]
 
 
 DESCRIPTION
diff --git a/Documentation/git-init.txt b/Documentation/git-init.txt
index b611d80..ad921fe 100644
--- a/Documentation/git-init.txt
+++ b/Documentation/git-init.txt
@@ -9,10 +9,10 @@
 SYNOPSIS
 --------
 [verse]
-'git init' [-q | --quiet] [--bare] [--template=<template_directory>]
-	  [--separate-git-dir <git dir>] [--object-format=<format>]
+'git init' [-q | --quiet] [--bare] [--template=<template-directory>]
+	  [--separate-git-dir <git-dir>] [--object-format=<format>]
 	  [-b <branch-name> | --initial-branch=<branch-name>]
-	  [--shared[=<permissions>]] [directory]
+	  [--shared[=<permissions>]] [<directory>]
 
 
 DESCRIPTION
@@ -57,12 +57,12 @@
 +
 include::object-format-disclaimer.txt[]
 
---template=<template_directory>::
+--template=<template-directory>::
 
 Specify the directory from which templates will be used.  (See the "TEMPLATE
 DIRECTORY" section below.)
 
---separate-git-dir=<git dir>::
+--separate-git-dir=<git-dir>::
 
 Instead of initializing the repository as a directory to either `$GIT_DIR` or
 `./.git/`, create a text file there containing the path to the actual
@@ -79,7 +79,7 @@
 `master`, but this is subject to change in the future; the name can be
 customized via the `init.defaultBranch` configuration variable).
 
---shared[=(false|true|umask|group|all|world|everybody|0xxx)]::
+--shared[=(false|true|umask|group|all|world|everybody|<perm>)]::
 
 Specify that the Git repository is to be shared amongst several users.  This
 allows users belonging to the same group to push into that
@@ -110,13 +110,16 @@
 
 Same as 'group', but make the repository readable by all users.
 
-'0xxx'::
+'<perm>'::
 
-'0xxx' is an octal number and each file will have mode '0xxx'. '0xxx' will
-override users' umask(2) value (and not only loosen permissions as 'group' and
-'all' does). '0640' will create a repository which is group-readable, but not
-group-writable or accessible to others. '0660' will create a repo that is
-readable and writable to the current user and group, but inaccessible to others.
+'<perm>' is a 3-digit octal number prefixed with `0` and each file
+will have mode '<perm>'. '<perm>' will override users' umask(2)
+value (and not only loosen permissions as 'group' and 'all'
+does). '0640' will create a repository which is group-readable, but
+not group-writable or accessible to others. '0660' will create a repo
+that is readable and writable to the current user and group, but
+inaccessible to others (directories and executable files get their
+`x` bit from the `r` bit for corresponding classes of users).
 --
 
 By default, the configuration flag `receive.denyNonFastForwards` is enabled
diff --git a/Documentation/git-log.txt b/Documentation/git-log.txt
index 0498e7b..20e87ce 100644
--- a/Documentation/git-log.txt
+++ b/Documentation/git-log.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git log' [<options>] [<revision range>] [[--] <path>...]
+'git log' [<options>] [<revision-range>] [[--] <path>...]
 
 DESCRIPTION
 -----------
@@ -81,13 +81,13 @@
 
 include::line-range-options.txt[]
 
-<revision range>::
+<revision-range>::
 	Show only commits in the specified revision range.  When no
-	<revision range> is specified, it defaults to `HEAD` (i.e. the
+	<revision-range> is specified, it defaults to `HEAD` (i.e. the
 	whole history leading to the current commit).  `origin..HEAD`
 	specifies all the commits reachable from the current commit
 	(i.e. `HEAD`), but not from `origin`. For a complete list of
-	ways to spell <revision range>, see the 'Specifying Ranges'
+	ways to spell <revision-range>, see the 'Specifying Ranges'
 	section of linkgit:gitrevisions[7].
 
 [--] <path>...::
diff --git a/Documentation/git-ls-files.txt b/Documentation/git-ls-files.txt
index 6d11ab5..48cc7c0 100644
--- a/Documentation/git-ls-files.txt
+++ b/Documentation/git-ls-files.txt
@@ -10,9 +10,9 @@
 --------
 [verse]
 'git ls-files' [-z] [-t] [-v] [-f]
-		(--[cached|deleted|others|ignored|stage|unmerged|killed|modified])*
-		(-[c|d|o|i|s|u|k|m])*
-		[--eol]
+		[-c|--cached] [-d|--deleted] [-o|--others] [-i|--|ignored]
+		[-s|--stage] [-u|--unmerged] [-k|--|killed] [-m|--modified]
+		[--directory [--no-empty-directory]] [--eol]
 		[--deduplicate]
 		[-x <pattern>|--exclude=<pattern>]
 		[-X <file>|--exclude-from=<file>]
@@ -187,6 +187,11 @@
 and in the working tree ("w/<eolinfo>") are shown for regular files,
 followed by the  ("attr/<eolattr>").
 
+--sparse::
+	If the index is sparse, show the sparse directories without expanding
+	to the contained files. Sparse directories will be shown with a
+	trailing slash, such as "x/" for a sparse directory "x".
+
 \--::
 	Do not interpret any more arguments as options.
 
diff --git a/Documentation/git-merge-file.txt b/Documentation/git-merge-file.txt
index f856032..7e9093f 100644
--- a/Documentation/git-merge-file.txt
+++ b/Documentation/git-merge-file.txt
@@ -70,6 +70,9 @@
 --diff3::
 	Show conflicts in "diff3" style.
 
+--zdiff3::
+	Show conflicts in "zdiff3" style.
+
 --ours::
 --theirs::
 --union::
diff --git a/Documentation/git-merge-index.txt b/Documentation/git-merge-index.txt
index 2ab84a9..eea56b3 100644
--- a/Documentation/git-merge-index.txt
+++ b/Documentation/git-merge-index.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git merge-index' [-o] [-q] <merge-program> (-a | [--] <file>*)
+'git merge-index' [-o] [-q] <merge-program> (-a | ( [--] <file>...) )
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-merge.txt b/Documentation/git-merge.txt
index e4f3352..3125473 100644
--- a/Documentation/git-merge.txt
+++ b/Documentation/git-merge.txt
@@ -12,7 +12,8 @@
 'git merge' [-n] [--stat] [--no-commit] [--squash] [--[no-]edit]
 	[--no-verify] [-s <strategy>] [-X <strategy-option>] [-S[<keyid>]]
 	[--[no-]allow-unrelated-histories]
-	[--[no-]rerere-autoupdate] [-m <msg>] [-F <file>] [<commit>...]
+	[--[no-]rerere-autoupdate] [-m <msg>] [-F <file>]
+	[--into-name <branch>] [<commit>...]
 'git merge' (--continue | --abort | --quit)
 
 DESCRIPTION
@@ -76,6 +77,11 @@
 used to give a good default for automated 'git merge'
 invocations. The automated message can include the branch description.
 
+--into-name <branch>::
+	Prepare the default merge message as if merging to the branch
+	`<branch>`, instead of the name of the real branch to which
+	the merge is made.
+
 -F <file>::
 --file=<file>::
 	Read the commit message to be used for the merge commit (in
@@ -240,7 +246,8 @@
 
 ------------
 Here are lines that are either unchanged from the common
-ancestor, or cleanly resolved because only one side changed.
+ancestor, or cleanly resolved because only one side changed,
+or cleanly resolved because both sides changed the same way.
 <<<<<<< yours:sample.txt
 Conflict resolution is hard;
 let's go shopping.
@@ -261,16 +268,37 @@
 other side wants to claim it is easy.
 
 An alternative style can be used by setting the "merge.conflictStyle"
-configuration variable to "diff3".  In "diff3" style, the above conflict
-may look like this:
+configuration variable to either "diff3" or "zdiff3".  In "diff3"
+style, the above conflict may look like this:
 
 ------------
 Here are lines that are either unchanged from the common
-ancestor, or cleanly resolved because only one side changed.
+ancestor, or cleanly resolved because only one side changed,
+<<<<<<< yours:sample.txt
+or cleanly resolved because both sides changed the same way.
+Conflict resolution is hard;
+let's go shopping.
+||||||| base:sample.txt
+or cleanly resolved because both sides changed identically.
+Conflict resolution is hard.
+=======
+or cleanly resolved because both sides changed the same way.
+Git makes conflict resolution easy.
+>>>>>>> theirs:sample.txt
+And here is another line that is cleanly resolved or unmodified.
+------------
+
+while in "zdiff3" style, it may look like this:
+
+------------
+Here are lines that are either unchanged from the common
+ancestor, or cleanly resolved because only one side changed,
+or cleanly resolved because both sides changed the same way.
 <<<<<<< yours:sample.txt
 Conflict resolution is hard;
 let's go shopping.
-|||||||
+||||||| base:sample.txt
+or cleanly resolved because both sides changed identically.
 Conflict resolution is hard.
 =======
 Git makes conflict resolution easy.
diff --git a/Documentation/git-p4.txt b/Documentation/git-p4.txt
index 38e5257..e21fcd8 100644
--- a/Documentation/git-p4.txt
+++ b/Documentation/git-p4.txt
@@ -9,10 +9,10 @@
 SYNOPSIS
 --------
 [verse]
-'git p4 clone' [<sync options>] [<clone options>] <p4 depot path>...
-'git p4 sync' [<sync options>] [<p4 depot path>...]
+'git p4 clone' [<sync-options>] [<clone-options>] <p4-depot-path>...
+'git p4 sync' [<sync-options>] [<p4-depot-path>...]
 'git p4 rebase'
-'git p4 submit' [<submit options>] [<master branch name>]
+'git p4 submit' [<submit-options>] [<master-branch-name>]
 
 
 DESCRIPTION
@@ -361,7 +361,7 @@
 	p4/master.  See the "Sync options" section above for more
 	information.
 
---commit <sha1>|<sha1..sha1>::
+--commit (<sha1>|<sha1>..<sha1>)::
     Submit only the specified commit or range of commits, instead of the full
     list of changes that are in the current Git branch.
 
diff --git a/Documentation/git-pack-objects.txt b/Documentation/git-pack-objects.txt
index dbfd1f9..f8344e1 100644
--- a/Documentation/git-pack-objects.txt
+++ b/Documentation/git-pack-objects.txt
@@ -13,8 +13,8 @@
 	[--no-reuse-delta] [--delta-base-offset] [--non-empty]
 	[--local] [--incremental] [--window=<n>] [--depth=<n>]
 	[--revs [--unpacked | --all]] [--keep-pack=<pack-name>]
-	[--stdout [--filter=<filter-spec>] | base-name]
-	[--shallow] [--keep-true-parents] [--[no-]sparse] < object-list
+	[--stdout [--filter=<filter-spec>] | <base-name>]
+	[--shallow] [--keep-true-parents] [--[no-]sparse] < <object-list>
 
 
 DESCRIPTION
diff --git a/Documentation/git-pack-redundant.txt b/Documentation/git-pack-redundant.txt
index f2869da..ee7034b 100644
--- a/Documentation/git-pack-redundant.txt
+++ b/Documentation/git-pack-redundant.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git pack-redundant' [ --verbose ] [ --alt-odb ] < --all | .pack filename ... >
+'git pack-redundant' [ --verbose ] [ --alt-odb ] ( --all | <pack-filename>... )
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index a1af21f..9da4647 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -714,9 +714,9 @@
 generates new fake commits based off limited information in the
 generated patches), those commits cannot be identified; instead it has
 to fall back to a commit summary.  Also, when merge.conflictStyle is
-set to diff3, the apply backend will use "constructed merge base" to
-label the content from the merge base, and thus provide no information
-about the merge base commit whatsoever.
+set to diff3 or zdiff3, the apply backend will use "constructed merge
+base" to label the content from the merge base, and thus provide no
+information about the merge base commit whatsoever.
 
 The merge backend works with the full commits on both sides of history
 and thus has no such limitations.
diff --git a/Documentation/git-reflog.txt b/Documentation/git-reflog.txt
index ff487ff..5ced7ad 100644
--- a/Documentation/git-reflog.txt
+++ b/Documentation/git-reflog.txt
@@ -17,12 +17,12 @@
 depending on the subcommand:
 
 [verse]
-'git reflog' ['show'] [log-options] [<ref>]
+'git reflog' ['show'] [<log-options>] [<ref>]
 'git reflog expire' [--expire=<time>] [--expire-unreachable=<time>]
 	[--rewrite] [--updateref] [--stale-fix]
 	[--dry-run | -n] [--verbose] [--all [--single-worktree] | <refs>...]
 'git reflog delete' [--rewrite] [--updateref]
-	[--dry-run | -n] [--verbose] ref@\{specifier\}...
+	[--dry-run | -n] [--verbose] <ref>@\{<specifier>\}...
 'git reflog exists' <ref>
 
 Reference logs, or "reflogs", record when the tips of branches and
diff --git a/Documentation/git-remote.txt b/Documentation/git-remote.txt
index 31c29c9..2bebc32 100644
--- a/Documentation/git-remote.txt
+++ b/Documentation/git-remote.txt
@@ -10,7 +10,7 @@
 --------
 [verse]
 'git remote' [-v | --verbose]
-'git remote add' [-t <branch>] [-m <master>] [-f] [--[no-]tags] [--mirror=(fetch|push)] <name> <url>
+'git remote add' [-t <branch>] [-m <master>] [-f] [--[no-]tags] [--mirror=(fetch|push)] <name> <URL>
 'git remote rename' <old> <new>
 'git remote remove' <name>
 'git remote set-head' <name> (-a | --auto | -d | --delete | <branch>)
@@ -18,7 +18,7 @@
 'git remote get-url' [--push] [--all] <name>
 'git remote set-url' [--push] <name> <newurl> [<oldurl>]
 'git remote set-url --add' [--push] <name> <newurl>
-'git remote set-url --delete' [--push] <name> <url>
+'git remote set-url --delete' [--push] <name> <URL>
 'git remote' [-v | --verbose] 'show' [-n] <name>...
 'git remote prune' [-n | --dry-run] <name>...
 'git remote' [-v | --verbose] 'update' [-p | --prune] [(<group> | <remote>)...]
@@ -47,7 +47,7 @@
 'add'::
 
 Add a remote named <name> for the repository at
-<url>.  The command `git fetch <name>` can then be used to create and
+<URL>.  The command `git fetch <name>` can then be used to create and
 update remote-tracking branches <name>/<branch>.
 +
 With `-f` option, `git fetch <name>` is run immediately after
@@ -152,7 +152,7 @@
 With `--add`, instead of changing existing URLs, new URL is added.
 +
 With `--delete`, instead of changing existing URLs, all URLs matching
-regex <url> are deleted for remote <name>.  Trying to delete all
+regex <URL> are deleted for remote <name>.  Trying to delete all
 non-push URLs is an error.
 +
 Note that the push URL and the fetch URL, even though they can
diff --git a/Documentation/git-repack.txt b/Documentation/git-repack.txt
index 7183fb4..ee30edc 100644
--- a/Documentation/git-repack.txt
+++ b/Documentation/git-repack.txt
@@ -76,8 +76,9 @@
 	linkgit:git-pack-objects[1].
 
 -q::
-	Pass the `-q` option to 'git pack-objects'. See
-	linkgit:git-pack-objects[1].
+--quiet::
+	Show no progress over the standard error stream and pass the `-q`
+	option to 'git pack-objects'. See linkgit:git-pack-objects[1].
 
 -n::
 	Do not update the server information with
diff --git a/Documentation/git-request-pull.txt b/Documentation/git-request-pull.txt
index 4d4392d..fa5a426 100644
--- a/Documentation/git-request-pull.txt
+++ b/Documentation/git-request-pull.txt
@@ -8,7 +8,7 @@
 SYNOPSIS
 --------
 [verse]
-'git request-pull' [-p] <start> <url> [<end>]
+'git request-pull' [-p] <start> <URL> [<end>]
 
 DESCRIPTION
 -----------
@@ -21,7 +21,7 @@
 The upstream project is expected to have the commit named by
 `<start>` and the output asks it to integrate the changes you made
 since that commit, up to the commit named by `<end>`, by visiting
-the repository named by `<url>`.
+the repository named by `<URL>`.
 
 
 OPTIONS
@@ -33,14 +33,14 @@
 	Commit to start at.  This names a commit that is already in
 	the upstream history.
 
-<url>::
+<URL>::
 	The repository URL to be pulled from.
 
 <end>::
 	Commit to end at (defaults to HEAD).  This names the commit
 	at the tip of the history you are asking to be pulled.
 +
-When the repository named by `<url>` has the commit at a tip of a
+When the repository named by `<URL>` has the commit at a tip of a
 ref that is different from the ref you have locally, you can use the
 `<local>:<remote>` syntax, to have its local name, a colon `:`, and
 its remote name.
diff --git a/Documentation/git-restore.txt b/Documentation/git-restore.txt
index 55bde91..5964810 100644
--- a/Documentation/git-restore.txt
+++ b/Documentation/git-restore.txt
@@ -92,8 +92,7 @@
 	The same as `--merge` option above, but changes the way the
 	conflicting hunks are presented, overriding the
 	`merge.conflictStyle` configuration variable.  Possible values
-	are "merge" (default) and "diff3" (in addition to what is
-	shown by "merge" style, shows the original contents).
+	are "merge" (default), "diff3", and "zdiff3".
 
 --ignore-unmerged::
 	When restoring files on the working tree from the index, do
diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
index 3db4eab..41cd8cb 100644
--- a/Documentation/git-send-email.txt
+++ b/Documentation/git-send-email.txt
@@ -9,7 +9,8 @@
 SYNOPSIS
 --------
 [verse]
-'git send-email' [<options>] <file|directory|rev-list options>...
+'git send-email' [<options>] <file|directory>...
+'git send-email' [<options>] <format-patch options>
 'git send-email' --dump-aliases
 
 
@@ -19,7 +20,8 @@
 Patches can be specified as files, directories (which will send all
 files in the directory), or directly as a revision list.  In the
 last case, any format accepted by linkgit:git-format-patch[1] can
-be passed to git send-email.
+be passed to git send-email, as well as options understood by
+linkgit:git-format-patch[1].
 
 The header of the email is configurable via command-line options.  If not
 specified on the command line, the user will be prompted with a ReadLine
diff --git a/Documentation/git-shortlog.txt b/Documentation/git-shortlog.txt
index c9c7f30..f64e770 100644
--- a/Documentation/git-shortlog.txt
+++ b/Documentation/git-shortlog.txt
@@ -8,7 +8,7 @@
 SYNOPSIS
 --------
 [verse]
-'git shortlog' [<options>] [<revision range>] [[--] <path>...]
+'git shortlog' [<options>] [<revision-range>] [[--] <path>...]
 git log --pretty=short | 'git shortlog' [<options>]
 
 DESCRIPTION
@@ -89,13 +89,13 @@
 If width is `0` (zero) then indent the lines of the output without wrapping
 them.
 
-<revision range>::
+<revision-range>::
 	Show only commits in the specified revision range.  When no
-	<revision range> is specified, it defaults to `HEAD` (i.e. the
+	<revision-range> is specified, it defaults to `HEAD` (i.e. the
 	whole history leading to the current commit).  `origin..HEAD`
 	specifies all the commits reachable from the current commit
 	(i.e. `HEAD`), but not from `origin`. For a complete list of
-	ways to spell <revision range>, see the "Specifying Ranges"
+	ways to spell <revision-range>, see the "Specifying Ranges"
 	section of linkgit:gitrevisions[7].
 
 [--] <path>...::
diff --git a/Documentation/git-sparse-checkout.txt b/Documentation/git-sparse-checkout.txt
index 42056ee..b81dbe0 100644
--- a/Documentation/git-sparse-checkout.txt
+++ b/Documentation/git-sparse-checkout.txt
@@ -11,7 +11,7 @@
 SYNOPSIS
 --------
 [verse]
-'git sparse-checkout <subcommand> [options]'
+'git sparse-checkout <subcommand> [<options>]'
 
 
 DESCRIPTION
@@ -30,28 +30,36 @@
 'list'::
 	Describe the patterns in the sparse-checkout file.
 
-'init'::
-	Enable the `core.sparseCheckout` setting. If the
-	sparse-checkout file does not exist, then populate it with
-	patterns that match every file in the root directory and
-	no other directories, then will remove all directories tracked
-	by Git. Add patterns to the sparse-checkout file to
-	repopulate the working directory.
+'set'::
+	Enable the necessary config settings
+	(extensions.worktreeConfig, core.sparseCheckout,
+	core.sparseCheckoutCone) if they are not already enabled, and
+	write a set of patterns to the sparse-checkout file from the
+	list of arguments following the 'set' subcommand. Update the
+	working directory to match the new patterns.
 +
-To avoid interfering with other worktrees, it first enables the
-`extensions.worktreeConfig` setting and makes sure to set the
-`core.sparseCheckout` setting in the worktree-specific config file.
+When the `--stdin` option is provided, the patterns are read from
+standard in as a newline-delimited list instead of from the arguments.
 +
-When `--cone` is provided, the `core.sparseCheckoutCone` setting is
-also set, allowing for better performance with a limited set of
-patterns (see 'CONE PATTERN SET' below).
+When `--cone` is passed or `core.sparseCheckoutCone` is enabled, the
+input list is considered a list of directories instead of
+sparse-checkout patterns.  This allows for better performance with a
+limited set of patterns (see 'CONE PATTERN SET' below).  Note that the
+set command will write patterns to the sparse-checkout file to include
+all files contained in those directories (recursively) as well as
+files that are siblings of ancestor directories. The input format
+matches the output of `git ls-tree --name-only`.  This includes
+interpreting pathnames that begin with a double quote (") as C-style
+quoted strings.  This may become the default in the future; --no-cone
+can be passed to request non-cone mode.
 +
-Use the `--[no-]sparse-index` option to toggle the use of the sparse
-index format. This reduces the size of the index to be more closely
-aligned with your sparse-checkout definition. This can have significant
-performance advantages for commands such as `git status` or `git add`.
-This feature is still experimental. Some commands might be slower with
-a sparse index until they are properly integrated with the feature.
+Use the `--[no-]sparse-index` option to use a sparse index (the
+default is to not use it).  A sparse index reduces the size of the
+index to be more closely aligned with your sparse-checkout
+definition. This can have significant performance advantages for
+commands such as `git status` or `git add`.  This feature is still
+experimental. Some commands might be slower with a sparse index until
+they are properly integrated with the feature.
 +
 **WARNING:** Using a sparse index requires modifying the index in a way
 that is not completely understood by external tools. If you have trouble
@@ -60,23 +68,6 @@
 understand the sparse directory entries index extension and may fail to
 interact with your repository until it is disabled.
 
-'set'::
-	Write a set of patterns to the sparse-checkout file, as given as
-	a list of arguments following the 'set' subcommand. Update the
-	working directory to match the new patterns. Enable the
-	core.sparseCheckout config setting if it is not already enabled.
-+
-When the `--stdin` option is provided, the patterns are read from
-standard in as a newline-delimited list instead of from the arguments.
-+
-When `core.sparseCheckoutCone` is enabled, the input list is considered a
-list of directories instead of sparse-checkout patterns. The command writes
-patterns to the sparse-checkout file to include all files contained in those
-directories (recursively) as well as files that are siblings of ancestor
-directories. The input format matches the output of `git ls-tree --name-only`.
-This includes interpreting pathnames that begin with a double quote (") as
-C-style quoted strings.
-
 'add'::
 	Update the sparse-checkout file to include additional patterns.
 	By default, these patterns are read from the command-line arguments,
@@ -93,12 +84,35 @@
 	cases, it can make sense to run `git sparse-checkout reapply` later
 	after cleaning up affected paths (e.g. resolving conflicts, undoing
 	or committing changes, etc.).
++
+The `reapply` command can also take `--[no-]cone` and `--[no-]sparse-index`
+flags, with the same meaning as the flags from the `set` command, in order
+to change which sparsity mode you are using without needing to also respecify
+all sparsity paths.
 
 'disable'::
 	Disable the `core.sparseCheckout` config setting, and restore the
-	working directory to include all files. Leaves the sparse-checkout
-	file intact so a later 'git sparse-checkout init' command may
-	return the working directory to the same state.
+	working directory to include all files.
+
+'init'::
+	Deprecated command that behaves like `set` with no specified paths.
+	May be removed in the future.
++
+Historically, `set` did not handle all the necessary config settings,
+which meant that both `init` and `set` had to be called.  Invoking
+both meant the `init` step would first remove nearly all tracked files
+(and in cone mode, ignored files too), then the `set` step would add
+many of the tracked files (but not ignored files) back.  In addition
+to the lost files, the performance and UI of this combination was
+poor.
++
+Also, historically, `init` would not actually initialize the
+sparse-checkout file if it already existed.  This meant it was
+possible to return to a sparse-checkout without remembering which
+paths to pass to a subsequent 'set' or 'add' command.  However,
+`--cone` and `--sparse-index` options would not be remembered across
+the disable command, so the easy restore of calling a plain `init`
+decreased in utility.
 
 SPARSE CHECKOUT
 ---------------
@@ -107,7 +121,7 @@
 It uses the skip-worktree bit (see linkgit:git-update-index[1]) to tell
 Git whether a file in the working directory is worth looking at. If
 the skip-worktree bit is set, then the file is ignored in the working
-directory. Git will not populate the contents of those files, which
+directory. Git will avoid populating the contents of those files, which
 makes a sparse checkout helpful when working in a repository with many
 files, but only a few are important to the current user.
 
@@ -117,10 +131,8 @@
 on this file. The files matching the patterns in the file will
 appear in the working directory, and the rest will not.
 
-To enable the sparse-checkout feature, run `git sparse-checkout init` to
-initialize a simple sparse-checkout file and enable the `core.sparseCheckout`
-config setting. Then, run `git sparse-checkout set` to modify the patterns in
-the sparse-checkout file.
+To enable the sparse-checkout feature, run `git sparse-checkout set` to
+set the patterns you want to use.
 
 To repopulate the working directory with all files, use the
 `git sparse-checkout disable` command.
diff --git a/Documentation/git-stage.txt b/Documentation/git-stage.txt
index 25bcda9..2f6aaa7 100644
--- a/Documentation/git-stage.txt
+++ b/Documentation/git-stage.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git stage' args...
+'git stage' <arg>...
 
 
 DESCRIPTION
diff --git a/Documentation/git-stash.txt b/Documentation/git-stash.txt
index be6084c..6e15f47 100644
--- a/Documentation/git-stash.txt
+++ b/Documentation/git-stash.txt
@@ -13,7 +13,7 @@
 'git stash' drop [-q|--quiet] [<stash>]
 'git stash' ( pop | apply ) [--index] [-q|--quiet] [<stash>]
 'git stash' branch <branchname> [<stash>]
-'git stash' [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
+'git stash' [push [-p|--patch] [-S|--staged] [-k|--[no-]keep-index] [-q|--quiet]
 	     [-u|--include-untracked] [-a|--all] [-m|--message <message>]
 	     [--pathspec-from-file=<file> [--pathspec-file-nul]]
 	     [--] [<pathspec>...]]
@@ -47,7 +47,7 @@
 COMMANDS
 --------
 
-push [-p|--patch] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [-m|--message <message>] [--pathspec-from-file=<file> [--pathspec-file-nul]] [--] [<pathspec>...]::
+push [-p|--patch] [-S|--staged] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [-m|--message <message>] [--pathspec-from-file=<file> [--pathspec-file-nul]] [--] [<pathspec>...]::
 
 	Save your local modifications to a new 'stash entry' and roll them
 	back to HEAD (in the working tree and in the index).
@@ -60,7 +60,7 @@
 are `stash -p` which acts as alias for `stash push -p` and pathspec elements,
 which are allowed after a double hyphen `--` for disambiguation.
 
-save [-p|--patch] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [<message>]::
+save [-p|--patch] [-S|--staged] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [<message>]::
 
 	This option is deprecated in favour of 'git stash push'.  It
 	differs from "stash push" in that it cannot take pathspec.
@@ -205,6 +205,16 @@
 The `--patch` option implies `--keep-index`.  You can use
 `--no-keep-index` to override this.
 
+-S::
+--staged::
+	This option is only valid for `push` and `save` commands.
++
+Stash only the changes that are currently staged. This is similar to
+basic `git commit` except the state is committed to the stash instead
+of current branch.
++
+The `--patch` option has priority over this one.
+
 --pathspec-from-file=<file>::
 	This option is only valid for `push` command.
 +
@@ -341,6 +351,24 @@
 $ git commit foo -m 'Remaining parts'
 ----------------------------------------------------------------
 
+Saving unrelated changes for future use::
+
+When you are in the middle of massive changes and you find some
+unrelated issue that you don't want to forget to fix, you can do the
+change(s), stage them, and use `git stash push --staged` to stash them
+out for future use. This is similar to committing the staged changes,
+only the commit ends-up being in the stash and not on the current branch.
++
+----------------------------------------------------------------
+# ... hack hack hack ...
+$ git add --patch foo           # add unrelated changes to the index
+$ git stash push --staged       # save these changes to the stash
+# ... hack hack hack, finish curent changes ...
+$ git commit -m 'Massive'       # commit fully tested changes
+$ git switch fixup-branch       # switch to another branch
+$ git stash pop                 # to finish work on the saved changes
+----------------------------------------------------------------
+
 Recovering stash entries that were cleared/dropped erroneously::
 
 If you mistakenly drop or clear stash entries, they cannot be recovered
diff --git a/Documentation/git-status.txt b/Documentation/git-status.txt
index 4a2c3e0..54a4b29 100644
--- a/Documentation/git-status.txt
+++ b/Documentation/git-status.txt
@@ -314,6 +314,14 @@
 ------------------------------------------------------------
 ....
 
+Stash Information
+^^^^^^^^^^^^^^^^^
+
+If `--show-stash` is given, one line is printed showing the number of stash
+entries if non-zero:
+
+    # stash <N>
+
 Changed Tracked Entries
 ^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/Documentation/git-svn.txt b/Documentation/git-svn.txt
index 222b556..4e92308 100644
--- a/Documentation/git-svn.txt
+++ b/Documentation/git-svn.txt
@@ -575,7 +575,7 @@
 -------
 
 --shared[=(false|true|umask|group|all|world|everybody)]::
---template=<template_directory>::
+--template=<template-directory>::
 	Only used with the 'init' command.
 	These are passed directly to 'git init'.
 
diff --git a/Documentation/git-switch.txt b/Documentation/git-switch.txt
index 5c438cd..bbcbdce 100644
--- a/Documentation/git-switch.txt
+++ b/Documentation/git-switch.txt
@@ -137,8 +137,7 @@
 	The same as `--merge` option above, but changes the way the
 	conflicting hunks are presented, overriding the
 	`merge.conflictStyle` configuration variable.  Possible values are
-	"merge" (default) and "diff3" (in addition to what is shown by
-	"merge" style, shows the original contents).
+	"merge" (default), "diff3", and "zdiff3".
 
 -q::
 --quiet::
@@ -152,7 +151,7 @@
 	attached to a terminal, regardless of `--quiet`.
 
 -t::
---track::
+--track [direct|inherit]::
 	When creating a new branch, set up "upstream" configuration.
 	`-c` is implied. See `--track` in linkgit:git-branch[1] for
 	details.
diff --git a/Documentation/git-var.txt b/Documentation/git-var.txt
index 6072f93..387cc1b 100644
--- a/Documentation/git-var.txt
+++ b/Documentation/git-var.txt
@@ -59,6 +59,9 @@
     The build you are using chose '{git-default-pager}' as the default.
 endif::git-default-pager[]
 
+GIT_DEFAULT_BRANCH::
+    The name of the first branch created in newly initialized repositories.
+
 SEE ALSO
 --------
 linkgit:git-commit-tree[1]
diff --git a/Documentation/git-web--browse.txt b/Documentation/git-web--browse.txt
index 8d162b5..f2f996c 100644
--- a/Documentation/git-web--browse.txt
+++ b/Documentation/git-web--browse.txt
@@ -8,7 +8,7 @@
 SYNOPSIS
 --------
 [verse]
-'git web{litdd}browse' [<options>] <url|file>...
+'git web{litdd}browse' [<options>] (<URL>|<file>)...
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 8a7cbdd..9e862fb 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -10,7 +10,7 @@
 --------
 [verse]
 'git worktree add' [-f] [--detach] [--checkout] [--lock [--reason <string>]] [-b <new-branch>] <path> [<commit-ish>]
-'git worktree list' [--porcelain]
+'git worktree list' [-v | --porcelain]
 'git worktree lock' [--reason <string>] <worktree>
 'git worktree move' <worktree> <new-path>
 'git worktree prune' [-n] [-v] [--expire <expire>]
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 281c5f8..13f83a2 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -832,8 +832,9 @@
 
 `GIT_TRACE_REDACT`::
 	By default, when tracing is activated, Git redacts the values of
-	cookies, the "Authorization:" header, and the "Proxy-Authorization:"
-	header. Set this variable to `0` to prevent this redaction.
+	cookies, the "Authorization:" header, the "Proxy-Authorization:"
+	header and packfile URIs. Set this variable to `0` to prevent this
+	redaction.
 
 `GIT_LITERAL_PATHSPECS`::
 	Setting this variable to `1` will cause Git to treat all
diff --git a/Documentation/gitcredentials.txt b/Documentation/gitcredentials.txt
index 758bf39..80517b4 100644
--- a/Documentation/gitcredentials.txt
+++ b/Documentation/gitcredentials.txt
@@ -132,7 +132,7 @@
 compares hostnames exactly, without considering whether two hosts are part of
 the same domain. Likewise, a config entry for `http://example.com` would not
 match: Git compares the protocols exactly.  However, you may use wildcards in
-the domain name and other pattern matching techniques as with the `http.<url>.*`
+the domain name and other pattern matching techniques as with the `http.<URL>.*`
 options.
 
 If the "pattern" URL does include a path component, then this too must match
@@ -147,7 +147,7 @@
 
 Options for a credential context can be configured either in
 `credential.*` (which applies to all credentials), or
-`credential.<url>.*`, where <url> matches the context as described
+`credential.<URL>.*`, where <URL> matches the context as described
 above.
 
 The following options are available in either location:
diff --git a/Documentation/gitsubmodules.txt b/Documentation/gitsubmodules.txt
index 891c8da..941858a 100644
--- a/Documentation/gitsubmodules.txt
+++ b/Documentation/gitsubmodules.txt
@@ -226,7 +226,7 @@
 ----------------------------------
 
   # Add a submodule
-  git submodule add <url> <path>
+  git submodule add <URL> <path>
 
   # Occasionally update the submodule to a new version:
   git -C <path> checkout <new version>
diff --git a/Documentation/gitworkflows.txt b/Documentation/gitworkflows.txt
index 47cf97f..5930526 100644
--- a/Documentation/gitworkflows.txt
+++ b/Documentation/gitworkflows.txt
@@ -394,7 +394,7 @@
 
 -------------------------------------
 Please pull from
-    <url> <branch>
+    <URL> <branch>
 -------------------------------------
 
 In that case, 'git pull' can do the fetch and merge in one go, as
@@ -403,7 +403,7 @@
 .Push/pull: Merging remote topics
 [caption="Recipe: "]
 =====================================
-`git pull <url> <branch>`
+`git pull <URL> <branch>`
 =====================================
 
 Occasionally, the maintainer may get merge conflicts when they try to
@@ -440,7 +440,7 @@
 .format-patch/am: Keeping topics up to date
 [caption="Recipe: "]
 =====================================
-`git pull --rebase <url> <branch>`
+`git pull --rebase <URL> <branch>`
 =====================================
 
 You can then fix the conflicts during the rebase.  Presumably you have
diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index ef6bd42..0b4c1c8 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -20,7 +20,7 @@
 
 * 'oneline'
 
-	  <hash> <title line>
+	  <hash> <title-line>
 +
 This is designed to be as compact as possible.
 
@@ -29,17 +29,17 @@
 	  commit <hash>
 	  Author: <author>
 
-	      <title line>
+	      <title-line>
 
 * 'medium'
 
 	  commit <hash>
 	  Author: <author>
-	  Date:   <author date>
+	  Date:   <author-date>
 
-	      <title line>
+	      <title-line>
 
-	      <full commit message>
+	      <full-commit-message>
 
 * 'full'
 
@@ -47,25 +47,25 @@
 	  Author: <author>
 	  Commit: <committer>
 
-	      <title line>
+	      <title-line>
 
-	      <full commit message>
+	      <full-commit-message>
 
 * 'fuller'
 
 	  commit <hash>
 	  Author:     <author>
-	  AuthorDate: <author date>
+	  AuthorDate: <author-date>
 	  Commit:     <committer>
-	  CommitDate: <committer date>
+	  CommitDate: <committer-date>
 
-	       <title line>
+	       <title-line>
 
-	       <full commit message>
+	       <full-commit-message>
 
 * 'reference'
 
-	  <abbrev hash> (<title line>, <short author date>)
+	  <abbrev-hash> (<title-line>, <short-author-date>)
 +
 This format is used to refer to another commit in a commit message and
 is the same as `--pretty='format:%C(auto)%h (%s, %ad)'`.  By default,
@@ -78,10 +78,10 @@
 
 	  From <hash> <date>
 	  From: <author>
-	  Date: <author date>
-	  Subject: [PATCH] <title line>
+	  Date: <author-date>
+	  Subject: [PATCH] <title-line>
 
-	  <full commit message>
+	  <full-commit-message>
 
 * 'mboxrd'
 +
@@ -101,9 +101,9 @@
 `git log --raw`. To get full object names in a raw diff format,
 use `--no-abbrev`.
 
-* 'format:<string>'
+* 'format:<format-string>'
 +
-The 'format:<string>' format allows you to specify which information
+The 'format:<format-string>' format allows you to specify which information
 you want to show. It works a little bit like printf format,
 with the notable exception that you get a newline with '%n'
 instead of '\n'.
@@ -220,6 +220,12 @@
 			  inconsistent when tags are added or removed at
 			  the same time.
 +
+** 'tags[=<bool-value>]': Instead of only considering annotated tags,
+   consider lightweight tags as well.
+** 'abbrev=<number>': Instead of using the default number of hexadecimal digits
+   (which will vary according to the number of objects in the repository with a
+   default of 7) of the abbreviated object name, use <number> digits, or as many
+   digits as needed to form a unique object name.
 ** 'match=<pattern>': Only consider tags matching the given
    `glob(7)` pattern, excluding the "refs/tags/" prefix.
 ** 'exclude=<pattern>': Do not consider tags matching the given
@@ -273,12 +279,7 @@
 			  If any option is provided multiple times the
 			  last occurrence wins.
 +
-The boolean options accept an optional value `[=<BOOL>]`. The values
-`true`, `false`, `on`, `off` etc. are all accepted. See the "boolean"
-sub-section in "EXAMPLES" in linkgit:git-config[1]. If a boolean
-option is given with no value, it's enabled.
-+
-** 'key=<K>': only show trailers with specified key. Matching is done
+** 'key=<key>': only show trailers with specified <key>. Matching is done
    case-insensitively and trailing colon is optional. If option is
    given multiple times trailer lines matching any of the keys are
    shown. This option automatically enables the `only` option so that
@@ -286,25 +287,25 @@
    desired it can be disabled with `only=false`.  E.g.,
    `%(trailers:key=Reviewed-by)` shows trailer lines with key
    `Reviewed-by`.
-** 'only[=<BOOL>]': select whether non-trailer lines from the trailer
+** 'only[=<bool>]': select whether non-trailer lines from the trailer
    block should be included.
-** 'separator=<SEP>': specify a separator inserted between trailer
+** 'separator=<sep>': specify a separator inserted between trailer
    lines. When this option is not given each trailer line is
-   terminated with a line feed character. The string SEP may contain
+   terminated with a line feed character. The string <sep> may contain
    the literal formatting codes described above. To use comma as
    separator one must use `%x2C` as it would otherwise be parsed as
    next option. E.g., `%(trailers:key=Ticket,separator=%x2C )`
    shows all trailer lines whose key is "Ticket" separated by a comma
    and a space.
-** 'unfold[=<BOOL>]': make it behave as if interpret-trailer's `--unfold`
+** 'unfold[=<bool>]': make it behave as if interpret-trailer's `--unfold`
    option was given. E.g.,
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
-** 'keyonly[=<BOOL>]': only show the key part of the trailer.
-** 'valueonly[=<BOOL>]': only show the value part of the trailer.
-** 'key_value_separator=<SEP>': specify a separator inserted between
+** 'keyonly[=<bool>]': only show the key part of the trailer.
+** 'valueonly[=<bool>]': only show the value part of the trailer.
+** 'key_value_separator=<sep>': specify a separator inserted between
    trailer lines. When this option is not given each trailer key-value
    pair is separated by ": ". Otherwise it shares the same semantics
-   as 'separator=<SEP>' above.
+   as 'separator=<sep>' above.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will
@@ -313,6 +314,11 @@
 decoration format if `--decorate` was not already provided on the command
 line.
 
+The boolean options accept an optional value `[=<bool-value>]`. The values
+`true`, `false`, `on`, `off` etc. are all accepted. See the "boolean"
+sub-section in "EXAMPLES" in linkgit:git-config[1]. If a boolean
+option is given with no value, it's enabled.
+
 If you add a `+` (plus sign) after '%' of a placeholder, a line-feed
 is inserted immediately before the expansion if and only if the
 placeholder expands to a non-empty string.
diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 24569b0..43a86fa 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -1047,7 +1047,7 @@
 has no effect.
 
 `--date=format:...` feeds the format `...` to your system `strftime`,
-except for %z and %Z, which are handled internally.
+except for %s, %z, and %Z, which are handled internally.
 Use `--date=format:%c` to show the date in your system locale's
 preferred format.  See the `strftime` manual for a complete list of
 format placeholders. When using `-local`, the correct syntax is
diff --git a/Documentation/technical/multi-pack-index.txt b/Documentation/technical/multi-pack-index.txt
index 86f40f2..b39c69d 100644
--- a/Documentation/technical/multi-pack-index.txt
+++ b/Documentation/technical/multi-pack-index.txt
@@ -17,12 +17,12 @@
 The multi-pack-index (MIDX for short) stores a list of objects
 and their offsets into multiple packfiles. It contains:
 
-- A list of packfile names.
-- A sorted list of object IDs.
-- A list of metadata for the ith object ID including:
-  - A value j referring to the jth packfile.
-  - An offset within the jth packfile for the object.
-- If large offsets are required, we use another list of large
+* A list of packfile names.
+* A sorted list of object IDs.
+* A list of metadata for the ith object ID including:
+** A value j referring to the jth packfile.
+** An offset within the jth packfile for the object.
+* If large offsets are required, we use another list of large
   offsets similar to version 2 pack-indexes.
 
 Thus, we can provide O(log N) lookup time for any number
@@ -87,11 +87,6 @@
   helpful to organize packfiles by object type (commit, tree, blob,
   etc.) and use this metadata to help that maintenance.
 
-- The partial clone feature records special "promisor" packs that
-  may point to objects that are not stored locally, but available
-  on request to a server. The multi-pack-index does not currently
-  track these promisor packs.
-
 Related Links
 -------------
 [0] https://bugs.chromium.org/p/git/issues/detail?id=6
diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt
index 21e8258..8a877d2 100644
--- a/Documentation/technical/protocol-v2.txt
+++ b/Documentation/technical/protocol-v2.txt
@@ -125,11 +125,11 @@
     empty-request = flush-pkt
     command-request = command
 		      capability-list
-		      [command-args]
+		      delim-pkt
+		      command-args
 		      flush-pkt
     command = PKT-LINE("command=" key LF)
-    command-args = delim-pkt
-		   *command-specific-arg
+    command-args = *command-specific-arg
 
     command-specific-args are packet line framed arguments defined by
     each individual command.
diff --git a/Documentation/technical/rerere.txt b/Documentation/technical/rerere.txt
index af5f9fc..35d4541 100644
--- a/Documentation/technical/rerere.txt
+++ b/Documentation/technical/rerere.txt
@@ -14,9 +14,9 @@
 
 Different conflict styles and branch names are normalized by stripping
 the labels from the conflict markers, and removing the common ancestor
-version from the `diff3` conflict style. Branches that are merged
-in different order are normalized by sorting the conflict hunks.  More
-on each of those steps in the following sections.
+version from the `diff3` or `zdiff3` conflict styles.  Branches that
+are merged in different order are normalized by sorting the conflict
+hunks.  More on each of those steps in the following sections.
 
 Once these two normalization operations are applied, a conflict ID is
 calculated based on the normalized conflict, which is later used by
@@ -42,8 +42,8 @@
     >>>>>>> AC
 
 Doing the analogous with AC2 (forking a branch ABAC2 off of branch AB
-and then merging branch AC2 into it), using the diff3 conflict style,
-we get a conflict like the following:
+and then merging branch AC2 into it), using the diff3 or zdiff3
+conflict style, we get a conflict like the following:
 
     <<<<<<< HEAD
     B
diff --git a/Documentation/urls-remotes.txt b/Documentation/urls-remotes.txt
index bd184cd..86d0008 100644
--- a/Documentation/urls-remotes.txt
+++ b/Documentation/urls-remotes.txt
@@ -26,14 +26,14 @@
 
 ------------
 	[remote "<name>"]
-		url = <url>
+		url = <URL>
 		pushurl = <pushurl>
 		push = <refspec>
 		fetch = <refspec>
 ------------
 
 The `<pushurl>` is used for pushes only. It is optional and defaults
-to `<url>`.
+to `<URL>`.
 
 Named file in `$GIT_DIR/remotes`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -67,10 +67,10 @@
 
 
 ------------
-	<url>#<head>
+	<URL>#<head>
 ------------
 
-`<url>` is required; `#<head>` is optional.
+`<URL>` is required; `#<head>` is optional.
 
 Depending on the operation, git will use one of the following
 refspecs, if you don't provide one on the command line.
diff --git a/GIT-VERSION-GEN b/GIT-VERSION-GEN
index 991308d..9a98b03 100755
--- a/GIT-VERSION-GEN
+++ b/GIT-VERSION-GEN
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 GVF=GIT-VERSION-FILE
-DEF_VER=v2.34.1
+DEF_VER=v2.35.0-rc0
 
 LF='
 '
diff --git a/Makefile b/Makefile
index 12be39a..5580859 100644
--- a/Makefile
+++ b/Makefile
@@ -256,6 +256,8 @@
 #
 # Define NO_DEFLATE_BOUND if your zlib does not have deflateBound.
 #
+# Define NO_UNCOMPRESS2 if your zlib does not have uncompress2.
+#
 # Define NO_NORETURN if using buggy versions of gcc 4.6+ and profile feedback,
 # as the compiler can crash (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49299)
 #
@@ -305,9 +307,6 @@
 #
 # Define NO_TCLTK if you do not want Tcl/Tk GUI.
 #
-# Define SANE_TEXT_GREP to "-a" if you use recent versions of GNU grep
-# and egrep that are pickier when their input contains non-ASCII data.
-#
 # The TCL_PATH variable governs the location of the Tcl interpreter
 # used to optimize git-gui for your system.  Only used if NO_TCLTK
 # is not set.  Defaults to the bare 'tclsh'.
@@ -735,6 +734,7 @@
 TEST_BUILTINS_OBJS += test-read-graph.o
 TEST_BUILTINS_OBJS += test-read-midx.o
 TEST_BUILTINS_OBJS += test-ref-store.o
+TEST_BUILTINS_OBJS += test-reftable.o
 TEST_BUILTINS_OBJS += test-regex.o
 TEST_BUILTINS_OBJS += test-repository.o
 TEST_BUILTINS_OBJS += test-revision-walking.o
@@ -813,6 +813,8 @@
 
 LIB_FILE = libgit.a
 XDIFF_LIB = xdiff/lib.a
+REFTABLE_LIB = reftable/libreftable.a
+REFTABLE_TEST_LIB = reftable/libreftable_test.a
 
 GENERATED_H += command-list.h
 GENERATED_H += config-list.h
@@ -1192,7 +1194,7 @@
 THIRD_PARTY_SOURCES += sha1collisiondetection/%
 THIRD_PARTY_SOURCES += sha1dc/%
 
-GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB)
+GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB)
 EXTLIBS =
 
 GIT_USER_AGENT = git/$(GIT_VERSION)
@@ -1204,6 +1206,7 @@
 # Set CFLAGS, LDFLAGS and other *FLAGS variables. These might be
 # tweaked by config.* below as well as the command-line, both of
 # which'll override these defaults.
+# Older versions of GCC may require adding "-std=gnu99" at the end.
 CFLAGS = -g -O2 -Wall
 LDFLAGS =
 CC_LD_DYNPATH = -Wl,-rpath,
@@ -1215,7 +1218,7 @@
 PTHREAD_CFLAGS =
 
 # For the 'sparse' target
-SPARSE_FLAGS ?=
+SPARSE_FLAGS ?= -std=gnu99
 SP_EXTRA_FLAGS = -Wno-universal-initializer
 
 # For informing GIT-BUILD-OPTIONS of the SANITIZE=leak target
@@ -1723,6 +1726,11 @@
 	BASIC_CFLAGS += -DNO_DEFLATE_BOUND
 endif
 
+ifdef NO_UNCOMPRESS2
+	BASIC_CFLAGS += -DNO_UNCOMPRESS2
+	REFTABLE_OBJS += compat/zlib-uncompress2.o
+endif
+
 ifdef NO_POSIX_GOODIES
 	BASIC_CFLAGS += -DNO_POSIX_GOODIES
 endif
@@ -1873,7 +1881,7 @@
 endif
 
 ifndef NO_MSGFMT_EXTENDED_OPTIONS
-	MSGFMT += --check --statistics
+	MSGFMT += --check
 endif
 
 ifdef HAVE_CLOCK_GETTIME
@@ -2104,11 +2112,6 @@
 BASIC_CFLAGS += -DDEFAULT_HELP_FORMAT='"$(DEFAULT_HELP_FORMAT)"'
 endif
 
-PAGER_ENV_SQ = $(subst ','\'',$(PAGER_ENV))
-PAGER_ENV_CQ = "$(subst ",\",$(subst \,\\,$(PAGER_ENV)))"
-PAGER_ENV_CQ_SQ = $(subst ','\'',$(PAGER_ENV_CQ))
-BASIC_CFLAGS += -DPAGER_ENV='$(PAGER_ENV_CQ_SQ)'
-
 ALL_CFLAGS += $(BASIC_CFLAGS)
 ALL_LDFLAGS += $(BASIC_LDFLAGS)
 
@@ -2215,14 +2218,20 @@
 		$(filter %.o,$^) $(LIBS)
 
 help.sp help.s help.o: command-list.h
-hook.sp hook.s hook.o: hook-list.h
+builtin/bugreport.sp builtin/bugreport.s builtin/bugreport.o: hook-list.h
 
-builtin/help.sp builtin/help.s builtin/help.o: config-list.h hook-list.h GIT-PREFIX
+builtin/help.sp builtin/help.s builtin/help.o: config-list.h GIT-PREFIX
 builtin/help.sp builtin/help.s builtin/help.o: EXTRA_CPPFLAGS = \
 	'-DGIT_HTML_PATH="$(htmldir_relative_SQ)"' \
 	'-DGIT_MAN_PATH="$(mandir_relative_SQ)"' \
 	'-DGIT_INFO_PATH="$(infodir_relative_SQ)"'
 
+PAGER_ENV_SQ = $(subst ','\'',$(PAGER_ENV))
+PAGER_ENV_CQ = "$(subst ",\",$(subst \,\\,$(PAGER_ENV)))"
+PAGER_ENV_CQ_SQ = $(subst ','\'',$(PAGER_ENV_CQ))
+pager.sp pager.s pager.o: EXTRA_CPPFLAGS = \
+	-DPAGER_ENV='$(PAGER_ENV_CQ_SQ)'
+
 version.sp version.s version.o: GIT-VERSION-FILE GIT-USER-AGENT
 version.sp version.s version.o: EXTRA_CPPFLAGS = \
 	'-DGIT_VERSION="$(GIT_VERSION)"' \
@@ -2252,25 +2261,10 @@
 hook-list.h: generate-hooklist.sh Documentation/githooks.txt
 	$(QUIET_GEN)$(SHELL_PATH) ./generate-hooklist.sh >$@
 
-SCRIPT_DEFINES = $(SHELL_PATH_SQ):$(DIFF_SQ):$(GIT_VERSION):\
-	$(localedir_SQ):$(NO_CURL):$(USE_GETTEXT_SCHEME):$(SANE_TOOL_PATH_SQ):\
-	$(gitwebdir_SQ):$(PERL_PATH_SQ):$(SANE_TEXT_GREP):$(PAGER_ENV):\
+SCRIPT_DEFINES = $(SHELL_PATH_SQ):$(DIFF_SQ):\
+	$(localedir_SQ):$(USE_GETTEXT_SCHEME):$(SANE_TOOL_PATH_SQ):\
+	$(gitwebdir_SQ):$(PERL_PATH_SQ):$(PAGER_ENV):\
 	$(perllibdir_SQ)
-define cmd_munge_script
-sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
-    -e 's|@SHELL_PATH@|$(SHELL_PATH_SQ)|' \
-    -e 's|@@DIFF@@|$(DIFF_SQ)|' \
-    -e 's|@@LOCALEDIR@@|$(localedir_SQ)|g' \
-    -e 's/@@NO_CURL@@/$(NO_CURL)/g' \
-    -e 's/@@USE_GETTEXT_SCHEME@@/$(USE_GETTEXT_SCHEME)/g' \
-    -e $(BROKEN_PATH_FIX) \
-    -e 's|@@GITWEBDIR@@|$(gitwebdir_SQ)|g' \
-    -e 's|@@PERL@@|$(PERL_PATH_SQ)|g' \
-    -e 's|@@SANE_TEXT_GREP@@|$(SANE_TEXT_GREP)|g' \
-    -e 's|@@PAGER_ENV@@|$(PAGER_ENV_SQ)|g' \
-    $@.sh >$@+
-endef
-
 GIT-SCRIPT-DEFINES: FORCE
 	@FLAGS='$(SCRIPT_DEFINES)'; \
 	    if test x"$$FLAGS" != x"`cat $@ 2>/dev/null`" ; then \
@@ -2278,6 +2272,18 @@
 		echo "$$FLAGS" >$@; \
             fi
 
+define cmd_munge_script
+sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
+    -e 's|@SHELL_PATH@|$(SHELL_PATH_SQ)|' \
+    -e 's|@@DIFF@@|$(DIFF_SQ)|' \
+    -e 's|@@LOCALEDIR@@|$(localedir_SQ)|g' \
+    -e 's/@@USE_GETTEXT_SCHEME@@/$(USE_GETTEXT_SCHEME)/g' \
+    -e $(BROKEN_PATH_FIX) \
+    -e 's|@@GITWEBDIR@@|$(gitwebdir_SQ)|g' \
+    -e 's|@@PERL@@|$(PERL_PATH_SQ)|g' \
+    -e 's|@@PAGER_ENV@@|$(PAGER_ENV_SQ)|g' \
+    $@.sh >$@+
+endef
 
 $(SCRIPT_SH_GEN) : % : %.sh GIT-SCRIPT-DEFINES
 	$(QUIET_GEN)$(cmd_munge_script) && \
@@ -2437,7 +2443,36 @@
 .PHONY: xdiff-objs
 xdiff-objs: $(XDIFF_OBJS)
 
+REFTABLE_OBJS += reftable/basics.o
+REFTABLE_OBJS += reftable/error.o
+REFTABLE_OBJS += reftable/block.o
+REFTABLE_OBJS += reftable/blocksource.o
+REFTABLE_OBJS += reftable/iter.o
+REFTABLE_OBJS += reftable/publicbasics.o
+REFTABLE_OBJS += reftable/merged.o
+REFTABLE_OBJS += reftable/pq.o
+REFTABLE_OBJS += reftable/reader.o
+REFTABLE_OBJS += reftable/record.o
+REFTABLE_OBJS += reftable/refname.o
+REFTABLE_OBJS += reftable/generic.o
+REFTABLE_OBJS += reftable/stack.o
+REFTABLE_OBJS += reftable/tree.o
+REFTABLE_OBJS += reftable/writer.o
+
+REFTABLE_TEST_OBJS += reftable/basics_test.o
+REFTABLE_TEST_OBJS += reftable/block_test.o
+REFTABLE_TEST_OBJS += reftable/dump.o
+REFTABLE_TEST_OBJS += reftable/merged_test.o
+REFTABLE_TEST_OBJS += reftable/pq_test.o
+REFTABLE_TEST_OBJS += reftable/record_test.o
+REFTABLE_TEST_OBJS += reftable/readwrite_test.o
+REFTABLE_TEST_OBJS += reftable/refname_test.o
+REFTABLE_TEST_OBJS += reftable/stack_test.o
+REFTABLE_TEST_OBJS += reftable/test_framework.o
+REFTABLE_TEST_OBJS += reftable/tree_test.o
+
 TEST_OBJS := $(patsubst %$X,%.o,$(TEST_PROGRAMS)) $(patsubst %,t/helper/%,$(TEST_BUILTINS_OBJS))
+
 .PHONY: test-objs
 test-objs: $(TEST_OBJS)
 
@@ -2453,9 +2488,16 @@
 OBJECTS += $(TEST_OBJS)
 OBJECTS += $(XDIFF_OBJS)
 OBJECTS += $(FUZZ_OBJS)
+OBJECTS += $(REFTABLE_OBJS) $(REFTABLE_TEST_OBJS)
+
 ifndef NO_CURL
 	OBJECTS += http.o http-walker.o remote-curl.o
 endif
+
+SCALAR_SOURCES := contrib/scalar/scalar.c
+SCALAR_OBJECTS := $(SCALAR_SOURCES:c=o)
+OBJECTS += $(SCALAR_OBJECTS)
+
 .PHONY: objects
 objects: $(OBJECTS)
 
@@ -2589,12 +2631,22 @@
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
 		$(CURL_LIBCURL) $(EXPAT_LIBEXPAT) $(LIBS)
 
+contrib/scalar/scalar$X: $(SCALAR_OBJECTS) GIT-LDFLAGS $(GITLIBS)
+	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) \
+		$(filter %.o,$^) $(LIBS)
+
 $(LIB_FILE): $(LIB_OBJS)
 	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
 
 $(XDIFF_LIB): $(XDIFF_OBJS)
 	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
 
+$(REFTABLE_LIB): $(REFTABLE_OBJS)
+	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
+
+$(REFTABLE_TEST_LIB): $(REFTABLE_TEST_OBJS)
+	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
+
 export DEFAULT_EDITOR DEFAULT_PAGER
 
 Documentation/GIT-EXCLUDED-PROGRAMS: FORCE
@@ -2893,7 +2945,7 @@
 
 t/helper/test-tool$X: $(patsubst %,t/helper/%,$(TEST_BUILTINS_OBJS))
 
-t/helper/test-%$X: t/helper/test-%.o GIT-LDFLAGS $(GITLIBS)
+t/helper/test-%$X: t/helper/test-%.o GIT-LDFLAGS $(GITLIBS) $(REFTABLE_TEST_LIB)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(filter %.a,$^) $(LIBS)
 
 check-sha1:: t/helper/test-tool$X
@@ -3231,7 +3283,7 @@
 clean: profile-clean coverage-clean cocciclean
 	$(RM) *.res
 	$(RM) $(OBJECTS)
-	$(RM) $(LIB_FILE) $(XDIFF_LIB)
+	$(RM) $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(REFTABLE_TEST_LIB)
 	$(RM) $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS) git$X
 	$(RM) $(TEST_PROGRAMS)
 	$(RM) $(FUZZ_PROGRAMS)
diff --git a/README.md b/README.md
index eb8115e..f6f43e7 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-[![Build status](https://github.com/git/git/workflows/CI/PR/badge.svg)](https://github.com/git/git/actions?query=branch%3Amaster+event%3Apush)
+[![Build status](https://github.com/git/git/workflows/CI/badge.svg)](https://github.com/git/git/actions?query=branch%3Amaster+event%3Apush)
 
 Git - fast, scalable, distributed revision control system
 =========================================================
diff --git a/RelNotes b/RelNotes
index 30a5e48..c27c205 120000
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes/2.34.1.txt
\ No newline at end of file
+Documentation/RelNotes/2.35.0.txt
\ No newline at end of file
diff --git a/add-patch.c b/add-patch.c
index 8c41cdf..573eef0 100644
--- a/add-patch.c
+++ b/add-patch.c
@@ -413,7 +413,7 @@
 		strvec_push(&args, ps->items[i].original);
 
 	setup_child_process(s, &cp, NULL);
-	cp.argv = args.v;
+	strvec_pushv(&cp.args, args.v);
 	res = capture_command(&cp, plain, 0);
 	if (res) {
 		strvec_clear(&args);
@@ -431,7 +431,7 @@
 
 		setup_child_process(s, &colored_cp, NULL);
 		xsnprintf((char *)args.v[color_arg_index], 8, "--color");
-		colored_cp.argv = args.v;
+		strvec_pushv(&colored_cp.args, args.v);
 		colored = &s->colored;
 		res = capture_command(&colored_cp, colored, 0);
 		strvec_clear(&args);
diff --git a/apply.c b/apply.c
index 43a0aeb..7ffadc3 100644
--- a/apply.c
+++ b/apply.c
@@ -133,10 +133,10 @@
 	int is_not_gitdir = !startup_info->have_repository;
 
 	if (state->apply_with_reject && state->threeway)
-		return error(_("--reject and --3way cannot be used together."));
+		return error(_("options '%s' and '%s' cannot be used together"), "--reject", "--3way");
 	if (state->threeway) {
 		if (is_not_gitdir)
-			return error(_("--3way outside a repository"));
+			return error(_("'%s' outside a repository"), "--3way");
 		state->check_index = 1;
 	}
 	if (state->apply_with_reject) {
@@ -147,10 +147,10 @@
 	if (!force_apply && (state->diffstat || state->numstat || state->summary || state->check || state->fake_ancestor))
 		state->apply = 0;
 	if (state->check_index && is_not_gitdir)
-		return error(_("--index outside a repository"));
+		return error(_("'%s' outside a repository"), "--index");
 	if (state->cached) {
 		if (is_not_gitdir)
-			return error(_("--cached outside a repository"));
+			return error(_("'%s' outside a repository"), "--cached");
 		state->check_index = 1;
 	}
 	if (state->ita_only && (state->check_index || is_not_gitdir))
@@ -3582,7 +3582,9 @@
 
 	/* No point falling back to 3-way merge in these cases */
 	if (patch->is_delete ||
-	    S_ISGITLINK(patch->old_mode) || S_ISGITLINK(patch->new_mode))
+	    S_ISGITLINK(patch->old_mode) || S_ISGITLINK(patch->new_mode) ||
+	    (patch->is_new && !patch->direct_to_threeway) ||
+	    (patch->is_rename && !patch->lines_added && !patch->lines_deleted))
 		return -1;
 
 	/* Preimage the patch was prepared for */
@@ -4752,8 +4754,10 @@
 	}
 
 	if (!list && !skipped_patch) {
-		error(_("unrecognized input"));
-		res = -128;
+		if (!state->allow_empty) {
+			error(_("No valid patches in input (allow with \"--allow-empty\")"));
+			res = -128;
+		}
 		goto end;
 	}
 
@@ -5071,7 +5075,7 @@
 			N_("leave the rejected hunks in corresponding *.rej files")),
 		OPT_BOOL(0, "allow-overlap", &state->allow_overlap,
 			N_("allow overlapping hunks")),
-		OPT__VERBOSE(&state->apply_verbosity, N_("be verbose")),
+		OPT__VERBOSITY(&state->apply_verbosity),
 		OPT_BIT(0, "inaccurate-eof", options,
 			N_("tolerate incorrectly detected missing new-line at the end of file"),
 			APPLY_OPT_INACCURATE_EOF),
@@ -5081,6 +5085,8 @@
 		OPT_CALLBACK(0, "directory", state, N_("root"),
 			N_("prepend <root> to all filenames"),
 			apply_option_parse_directory),
+		OPT_BOOL(0, "allow-empty", &state->allow_empty,
+			N_("don't return error for empty patches")),
 		OPT_END()
 	};
 
diff --git a/apply.h b/apply.h
index da3d95f..16202da 100644
--- a/apply.h
+++ b/apply.h
@@ -66,6 +66,7 @@
 	int threeway;
 	int unidiff_zero;
 	int unsafe_paths;
+	int allow_empty;
 
 	/* Other non boolean parameters */
 	struct repository *repo;
diff --git a/archive-tar.c b/archive-tar.c
index 05d2455..3c74db1 100644
--- a/archive-tar.c
+++ b/archive-tar.c
@@ -430,7 +430,6 @@
 {
 	struct strbuf cmd = STRBUF_INIT;
 	struct child_process filter = CHILD_PROCESS_INIT;
-	const char *argv[2];
 	int r;
 
 	if (!ar->data)
@@ -440,14 +439,12 @@
 	if (args->compression_level >= 0)
 		strbuf_addf(&cmd, " -%d", args->compression_level);
 
-	argv[0] = cmd.buf;
-	argv[1] = NULL;
-	filter.argv = argv;
+	strvec_push(&filter.args, cmd.buf);
 	filter.use_shell = 1;
 	filter.in = -1;
 
 	if (start_command(&filter) < 0)
-		die_errno(_("unable to start '%s' filter"), argv[0]);
+		die_errno(_("unable to start '%s' filter"), cmd.buf);
 	close(1);
 	if (dup2(filter.in, 1) < 0)
 		die_errno(_("unable to redirect descriptor"));
@@ -457,7 +454,7 @@
 
 	close(1);
 	if (finish_command(&filter) != 0)
-		die(_("'%s' filter reported error"), argv[0]);
+		die(_("'%s' filter reported error"), cmd.buf);
 
 	strbuf_release(&cmd);
 	return r;
diff --git a/archive.c b/archive.c
index a3bbb09..d571249 100644
--- a/archive.c
+++ b/archive.c
@@ -185,7 +185,7 @@
 
 	buffer = object_file_to_archive(args, path.buf, oid, mode, &type, &size);
 	if (!buffer)
-		return error(_("cannot read %s"), oid_to_hex(oid));
+		return error(_("cannot read '%s'"), oid_to_hex(oid));
 	err = write_entry(args, oid, path.buf, path.len, mode, buffer, size);
 	free(buffer);
 	return err;
@@ -338,7 +338,7 @@
 
 		strbuf_reset(&content);
 		if (strbuf_read_file(&content, path, info->stat.st_size) < 0)
-			err = error_errno(_("could not read '%s'"), path);
+			err = error_errno(_("cannot read '%s'"), path);
 		else
 			err = write_entry(args, &fake_oid, path_in_archive.buf,
 					  path_in_archive.len,
@@ -577,11 +577,11 @@
 	if (remote)
 		die(_("Unexpected option --remote"));
 	if (exec)
-		die(_("Option --exec can only be used together with --remote"));
+		die(_("the option '%s' requires '%s'"), "--exec", "--remote");
 	if (output)
 		die(_("Unexpected option --output"));
 	if (is_remote && args->extra_files.nr)
-		die(_("Options --add-file and --remote cannot be used together"));
+		die(_("options '%s' and '%s' cannot be used together"), "--add-file", "--remote");
 
 	if (!base)
 		base = "";
diff --git a/branch.c b/branch.c
index 07a4643..5d20a2e 100644
--- a/branch.c
+++ b/branch.c
@@ -11,7 +11,7 @@
 
 struct tracking {
 	struct refspec_item spec;
-	char *src;
+	struct string_list *srcs;
 	const char *remote;
 	int matches;
 };
@@ -22,11 +22,11 @@
 
 	if (!remote_find_tracking(remote, &tracking->spec)) {
 		if (++tracking->matches == 1) {
-			tracking->src = tracking->spec.src;
+			string_list_append(tracking->srcs, tracking->spec.src);
 			tracking->remote = remote->name;
 		} else {
 			free(tracking->spec.src);
-			FREE_AND_NULL(tracking->src);
+			string_list_clear(tracking->srcs, 0);
 		}
 		tracking->spec.src = NULL;
 	}
@@ -49,25 +49,46 @@
 	return 0;
 }
 
-static const char tracking_advice[] =
-N_("\n"
-"After fixing the error cause you may try to fix up\n"
-"the remote tracking information by invoking\n"
-"\"git branch --set-upstream-to=%s%s%s\".");
-
-int install_branch_config(int flag, const char *local, const char *origin, const char *remote)
+/**
+ * Install upstream tracking configuration for a branch; specifically, add
+ * `branch.<name>.remote` and `branch.<name>.merge` entries.
+ *
+ * `flag` contains integer flags for options; currently only
+ * BRANCH_CONFIG_VERBOSE is checked.
+ *
+ * `local` is the name of the branch whose configuration we're installing.
+ *
+ * `origin` is the name of the remote owning the upstream branches. NULL means
+ * the upstream branches are local to this repo.
+ *
+ * `remotes` is a list of refs that are upstream of local
+ */
+static int install_branch_config_multiple_remotes(int flag, const char *local,
+		const char *origin, struct string_list *remotes)
 {
 	const char *shortname = NULL;
 	struct strbuf key = STRBUF_INIT;
+	struct string_list_item *item;
 	int rebasing = should_setup_rebase(origin);
 
-	if (skip_prefix(remote, "refs/heads/", &shortname)
-	    && !strcmp(local, shortname)
-	    && !origin) {
-		warning(_("Not setting branch %s as its own upstream."),
-			local);
-		return 0;
-	}
+	if (!remotes->nr)
+		BUG("must provide at least one remote for branch config");
+	if (rebasing && remotes->nr > 1)
+		die(_("cannot inherit upstream tracking configuration of "
+		      "multiple refs when rebasing is requested"));
+
+	/*
+	 * If the new branch is trying to track itself, something has gone
+	 * wrong. Warn the user and don't proceed any further.
+	 */
+	if (!origin)
+		for_each_string_list_item(item, remotes)
+			if (skip_prefix(item->string, "refs/heads/", &shortname)
+			    && !strcmp(local, shortname)) {
+				warning(_("not setting branch '%s' as its own upstream"),
+					local);
+				return 0;
+			}
 
 	strbuf_addf(&key, "branch.%s.remote", local);
 	if (git_config_set_gently(key.buf, origin ? origin : ".") < 0)
@@ -75,8 +96,17 @@
 
 	strbuf_reset(&key);
 	strbuf_addf(&key, "branch.%s.merge", local);
-	if (git_config_set_gently(key.buf, remote) < 0)
+	/*
+	 * We want to overwrite any existing config with all the branches in
+	 * "remotes". Override any existing config, then write our branches. If
+	 * more than one is provided, use CONFIG_REGEX_NONE to preserve what
+	 * we've written so far.
+	 */
+	if (git_config_set_gently(key.buf, NULL) < 0)
 		goto out_err;
+	for_each_string_list_item(item, remotes)
+		if (git_config_set_multivar_gently(key.buf, item->string, CONFIG_REGEX_NONE, 0) < 0)
+			goto out_err;
 
 	if (rebasing) {
 		strbuf_reset(&key);
@@ -87,45 +117,106 @@
 	strbuf_release(&key);
 
 	if (flag & BRANCH_CONFIG_VERBOSE) {
-		if (shortname) {
-			if (origin)
-				printf_ln(rebasing ?
-					  _("Branch '%s' set up to track remote branch '%s' from '%s' by rebasing.") :
-					  _("Branch '%s' set up to track remote branch '%s' from '%s'."),
-					  local, shortname, origin);
-			else
-				printf_ln(rebasing ?
-					  _("Branch '%s' set up to track local branch '%s' by rebasing.") :
-					  _("Branch '%s' set up to track local branch '%s'."),
-					  local, shortname);
-		} else {
-			if (origin)
-				printf_ln(rebasing ?
-					  _("Branch '%s' set up to track remote ref '%s' by rebasing.") :
-					  _("Branch '%s' set up to track remote ref '%s'."),
-					  local, remote);
-			else
-				printf_ln(rebasing ?
-					  _("Branch '%s' set up to track local ref '%s' by rebasing.") :
-					  _("Branch '%s' set up to track local ref '%s'."),
-					  local, remote);
+		struct strbuf tmp_ref_name = STRBUF_INIT;
+		struct string_list friendly_ref_names = STRING_LIST_INIT_DUP;
+
+		for_each_string_list_item(item, remotes) {
+			shortname = item->string;
+			skip_prefix(shortname, "refs/heads/", &shortname);
+			if (origin) {
+				strbuf_addf(&tmp_ref_name, "%s/%s",
+					    origin, shortname);
+				string_list_append_nodup(
+					&friendly_ref_names,
+					strbuf_detach(&tmp_ref_name, NULL));
+			} else {
+				string_list_append(
+					&friendly_ref_names, shortname);
+			}
 		}
+
+		if (remotes->nr == 1) {
+			/*
+			 * Rebasing is only allowed in the case of a single
+			 * upstream branch.
+			 */
+			printf_ln(rebasing ?
+				_("branch '%s' set up to track '%s' by rebasing.") :
+				_("branch '%s' set up to track '%s'."),
+				local, friendly_ref_names.items[0].string);
+		} else {
+			printf_ln(_("branch '%s' set up to track:"), local);
+			for_each_string_list_item(item, &friendly_ref_names)
+				printf_ln("  %s", item->string);
+		}
+
+		string_list_clear(&friendly_ref_names, 0);
 	}
 
 	return 0;
 
 out_err:
 	strbuf_release(&key);
-	error(_("Unable to write upstream branch configuration"));
+	error(_("unable to write upstream branch configuration"));
 
-	advise(_(tracking_advice),
-	       origin ? origin : "",
-	       origin ? "/" : "",
-	       shortname ? shortname : remote);
+	advise(_("\nAfter fixing the error cause you may try to fix up\n"
+		"the remote tracking information by invoking:"));
+	if (remotes->nr == 1)
+		advise("  git branch --set-upstream-to=%s%s%s",
+			origin ? origin : "",
+			origin ? "/" : "",
+			remotes->items[0].string);
+	else {
+		advise("  git config --add branch.\"%s\".remote %s",
+			local, origin ? origin : ".");
+		for_each_string_list_item(item, remotes)
+			advise("  git config --add branch.\"%s\".merge %s",
+				local, item->string);
+	}
 
 	return -1;
 }
 
+int install_branch_config(int flag, const char *local, const char *origin,
+		const char *remote)
+{
+	int ret;
+	struct string_list remotes = STRING_LIST_INIT_DUP;
+
+	string_list_append(&remotes, remote);
+	ret = install_branch_config_multiple_remotes(flag, local, origin, &remotes);
+	string_list_clear(&remotes, 0);
+	return ret;
+}
+
+static int inherit_tracking(struct tracking *tracking, const char *orig_ref)
+{
+	const char *bare_ref;
+	struct branch *branch;
+	int i;
+
+	bare_ref = orig_ref;
+	skip_prefix(orig_ref, "refs/heads/", &bare_ref);
+
+	branch = branch_get(bare_ref);
+	if (!branch->remote_name) {
+		warning(_("asked to inherit tracking from '%s', but no remote is set"),
+			bare_ref);
+		return -1;
+	}
+
+	if (branch->merge_nr < 1 || !branch->merge_name || !branch->merge_name[0]) {
+		warning(_("asked to inherit tracking from '%s', but no merge configuration is set"),
+			bare_ref);
+		return -1;
+	}
+
+	tracking->remote = xstrdup(branch->remote_name);
+	for (i = 0; i < branch->merge_nr; i++)
+		string_list_append(tracking->srcs, branch->merge_name[i]);
+	return 0;
+}
+
 /*
  * This is called when new_ref is branched off of orig_ref, and tries
  * to infer the settings for branch.<new_ref>.{remote,merge} from the
@@ -135,11 +226,15 @@
 			   enum branch_track track, int quiet)
 {
 	struct tracking tracking;
+	struct string_list tracking_srcs = STRING_LIST_INIT_DUP;
 	int config_flags = quiet ? 0 : BRANCH_CONFIG_VERBOSE;
 
 	memset(&tracking, 0, sizeof(tracking));
 	tracking.spec.dst = (char *)orig_ref;
-	if (for_each_remote(find_tracked_branch, &tracking))
+	tracking.srcs = &tracking_srcs;
+	if (track != BRANCH_TRACK_INHERIT)
+		for_each_remote(find_tracked_branch, &tracking);
+	else if (inherit_tracking(&tracking, orig_ref))
 		return;
 
 	if (!tracking.matches)
@@ -147,20 +242,23 @@
 		case BRANCH_TRACK_ALWAYS:
 		case BRANCH_TRACK_EXPLICIT:
 		case BRANCH_TRACK_OVERRIDE:
+		case BRANCH_TRACK_INHERIT:
 			break;
 		default:
 			return;
 		}
 
 	if (tracking.matches > 1)
-		die(_("Not tracking: ambiguous information for ref %s"),
+		die(_("not tracking: ambiguous information for ref %s"),
 		    orig_ref);
 
-	if (install_branch_config(config_flags, new_ref, tracking.remote,
-			      tracking.src ? tracking.src : orig_ref) < 0)
+	if (tracking.srcs->nr < 1)
+		string_list_append(tracking.srcs, orig_ref);
+	if (install_branch_config_multiple_remotes(config_flags, new_ref,
+				tracking.remote, tracking.srcs) < 0)
 		exit(-1);
 
-	free(tracking.src);
+	string_list_clear(tracking.srcs, 0);
 }
 
 int read_branch_desc(struct strbuf *buf, const char *branch_name)
@@ -186,7 +284,7 @@
 int validate_branchname(const char *name, struct strbuf *ref)
 {
 	if (strbuf_check_branch_ref(ref, name))
-		die(_("'%s' is not a valid branch name."), name);
+		die(_("'%s' is not a valid branch name"), name);
 
 	return ref_exists(ref->buf);
 }
@@ -199,18 +297,23 @@
  */
 int validate_new_branchname(const char *name, struct strbuf *ref, int force)
 {
-	const char *head;
+	struct worktree **worktrees;
+	const struct worktree *wt;
 
 	if (!validate_branchname(name, ref))
 		return 0;
 
 	if (!force)
-		die(_("A branch named '%s' already exists."),
+		die(_("a branch named '%s' already exists"),
 		    ref->buf + strlen("refs/heads/"));
 
-	head = resolve_ref_unsafe("HEAD", 0, NULL, NULL);
-	if (!is_bare_repository() && head && !strcmp(head, ref->buf))
-		die(_("Cannot force update the current branch."));
+	worktrees = get_worktrees();
+	wt = find_shared_symref(worktrees, "HEAD", ref->buf);
+	if (wt && !wt->is_bare)
+		die(_("cannot force update the branch '%s' "
+		      "checked out at '%s'"),
+		    ref->buf + strlen("refs/heads/"), wt->path);
+	free_worktrees(worktrees);
 
 	return 1;
 }
@@ -230,7 +333,7 @@
 }
 
 static const char upstream_not_branch[] =
-N_("Cannot setup tracking information; starting point '%s' is not a branch.");
+N_("cannot set up tracking information; starting point '%s' is not a branch");
 static const char upstream_missing[] =
 N_("the requested upstream branch '%s' does not exist");
 static const char upstream_advice[] =
@@ -278,7 +381,7 @@
 			}
 			die(_(upstream_missing), start_name);
 		}
-		die(_("Not a valid object name: '%s'."), start_name);
+		die(_("not a valid object name: '%s'"), start_name);
 	}
 
 	switch (dwim_ref(start_name, strlen(start_name), &oid, &real_ref, 0)) {
@@ -298,12 +401,12 @@
 		}
 		break;
 	default:
-		die(_("Ambiguous object name: '%s'."), start_name);
+		die(_("ambiguous object name: '%s'"), start_name);
 		break;
 	}
 
 	if ((commit = lookup_commit_reference(r, &oid)) == NULL)
-		die(_("Not a valid branch point: '%s'."), start_name);
+		die(_("not a valid branch point: '%s'"), start_name);
 	oidcpy(&oid, &commit->object.oid);
 
 	if (reflog)
@@ -357,14 +460,16 @@
 
 void die_if_checked_out(const char *branch, int ignore_current_worktree)
 {
+	struct worktree **worktrees = get_worktrees();
 	const struct worktree *wt;
 
-	wt = find_shared_symref("HEAD", branch);
-	if (!wt || (ignore_current_worktree && wt->is_current))
-		return;
-	skip_prefix(branch, "refs/heads/", &branch);
-	die(_("'%s' is already checked out at '%s'"),
-	    branch, wt->path);
+	wt = find_shared_symref(worktrees, "HEAD", branch);
+	if (wt && (!ignore_current_worktree || !wt->is_current)) {
+		skip_prefix(branch, "refs/heads/", &branch);
+		die(_("'%s' is already checked out at '%s'"), branch, wt->path);
+	}
+
+	free_worktrees(worktrees);
 }
 
 int replace_each_worktree_head_symref(const char *oldref, const char *newref,
diff --git a/branch.h b/branch.h
index df0be61..815dcd4 100644
--- a/branch.h
+++ b/branch.h
@@ -10,7 +10,8 @@
 	BRANCH_TRACK_REMOTE,
 	BRANCH_TRACK_ALWAYS,
 	BRANCH_TRACK_EXPLICIT,
-	BRANCH_TRACK_OVERRIDE
+	BRANCH_TRACK_OVERRIDE,
+	BRANCH_TRACK_INHERIT,
 };
 
 extern enum branch_track git_branch_track;
diff --git a/builtin/add.c b/builtin/add.c
index ef6b619..84dff3e 100644
--- a/builtin/add.c
+++ b/builtin/add.c
@@ -302,15 +302,11 @@
 static int edit_patch(int argc, const char **argv, const char *prefix)
 {
 	char *file = git_pathdup("ADD_EDIT.patch");
-	const char *apply_argv[] = { "apply", "--recount", "--cached",
-		NULL, NULL };
 	struct child_process child = CHILD_PROCESS_INIT;
 	struct rev_info rev;
 	int out;
 	struct stat st;
 
-	apply_argv[3] = file;
-
 	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
 
 	if (read_cache() < 0)
@@ -338,7 +334,8 @@
 		die(_("Empty patch. Aborted."));
 
 	child.git_cmd = 1;
-	child.argv = apply_argv;
+	strvec_pushl(&child.args, "apply", "--recount", "--cached", file,
+		     NULL);
 	if (run_command(&child))
 		die(_("Could not apply '%s'"), file);
 
@@ -510,9 +507,9 @@
 		add_interactive = 1;
 	if (add_interactive) {
 		if (show_only)
-			die(_("--dry-run is incompatible with --interactive/--patch"));
+			die(_("options '%s' and '%s' cannot be used together"), "--dry-run", "--interactive/--patch");
 		if (pathspec_from_file)
-			die(_("--pathspec-from-file is incompatible with --interactive/--patch"));
+			die(_("options '%s' and '%s' cannot be used together"), "--pathspec-from-file", "--interactive/--patch");
 		exit(interactive_add(argv + 1, prefix, patch_interactive));
 	}
 	if (legacy_stash_p) {
@@ -529,7 +526,7 @@
 
 	if (edit_interactive) {
 		if (pathspec_from_file)
-			die(_("--pathspec-from-file is incompatible with --edit"));
+			die(_("options '%s' and '%s' cannot be used together"), "--pathspec-from-file", "--edit");
 		return(edit_patch(argc, argv, prefix));
 	}
 	argc--;
@@ -541,10 +538,10 @@
 		addremove = 0; /* "-u" was given but not "-A" */
 
 	if (addremove && take_worktree_changes)
-		die(_("-A and -u are mutually incompatible"));
+		die(_("options '%s' and '%s' cannot be used together"), "-A", "-u");
 
 	if (!show_only && ignore_missing)
-		die(_("Option --ignore-missing can only be used together with --dry-run"));
+		die(_("the option '%s' requires '%s'"), "--ignore-missing", "--dry-run");
 
 	if (chmod_arg && ((chmod_arg[0] != '-' && chmod_arg[0] != '+') ||
 			  chmod_arg[1] != 'x' || chmod_arg[2]))
@@ -569,14 +566,14 @@
 
 	if (pathspec_from_file) {
 		if (pathspec.nr)
-			die(_("--pathspec-from-file is incompatible with pathspec arguments"));
+			die(_("'%s' and pathspec arguments cannot be used together"), "--pathspec-from-file");
 
 		parse_pathspec_file(&pathspec, PATHSPEC_ATTR,
 				    PATHSPEC_PREFER_FULL |
 				    PATHSPEC_SYMLINK_LEADING_PATH,
 				    prefix, pathspec_from_file, pathspec_file_nul);
 	} else if (pathspec_file_nul) {
-		die(_("--pathspec-file-nul requires --pathspec-from-file"));
+		die(_("the option '%s' requires '%s'"), "--pathspec-file-nul", "--pathspec-from-file");
 	}
 
 	if (require_pathspec && pathspec.nr == 0) {
diff --git a/builtin/am.c b/builtin/am.c
index 8677ea2..b6be1f1 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -87,6 +87,12 @@
 	SHOW_PATCH_DIFF = 1,
 };
 
+enum empty_action {
+	STOP_ON_EMPTY_COMMIT = 0,  /* output errors and stop in the middle of an am session */
+	DROP_EMPTY_COMMIT,         /* skip with a notice message, unless "--quiet" has been passed */
+	KEEP_EMPTY_COMMIT,         /* keep recording as empty commits */
+};
+
 struct am_state {
 	/* state directory path */
 	char *dir;
@@ -118,6 +124,7 @@
 	int message_id;
 	int scissors; /* enum scissors_type */
 	int quoted_cr; /* enum quoted_cr_action */
+	int empty_type; /* enum empty_action */
 	struct strvec git_apply_opts;
 	const char *resolvemsg;
 	int committer_date_is_author_date;
@@ -178,6 +185,25 @@
 	return 0;
 }
 
+static int am_option_parse_empty(const struct option *opt,
+				     const char *arg, int unset)
+{
+	int *opt_value = opt->value;
+
+	BUG_ON_OPT_NEG(unset);
+
+	if (!strcmp(arg, "stop"))
+		*opt_value = STOP_ON_EMPTY_COMMIT;
+	else if (!strcmp(arg, "drop"))
+		*opt_value = DROP_EMPTY_COMMIT;
+	else if (!strcmp(arg, "keep"))
+		*opt_value = KEEP_EMPTY_COMMIT;
+	else
+		return error(_("Invalid value for --empty: %s"), arg);
+
+	return 0;
+}
+
 /**
  * Returns path relative to the am_state directory.
  */
@@ -1126,6 +1152,12 @@
 
 		printf_ln(_("When you have resolved this problem, run \"%s --continue\"."), cmdline);
 		printf_ln(_("If you prefer to skip this patch, run \"%s --skip\" instead."), cmdline);
+
+		if (advice_enabled(ADVICE_AM_WORK_DIR) &&
+		    is_empty_or_missing_file(am_path(state, "patch")) &&
+		    !repo_index_has_changes(the_repository, NULL, NULL))
+			printf_ln(_("To record the empty patch as an empty commit, run \"%s --allow-empty\"."), cmdline);
+
 		printf_ln(_("To restore the original branch and stop patching, run \"%s --abort\"."), cmdline);
 	}
 
@@ -1248,11 +1280,6 @@
 		goto finish;
 	}
 
-	if (is_empty_or_missing_file(am_path(state, "patch"))) {
-		printf_ln(_("Patch is empty."));
-		die_user_resolve(state);
-	}
-
 	strbuf_addstr(&msg, "\n\n");
 	strbuf_addbuf(&msg, &mi.log_message);
 	strbuf_stripspace(&msg, 0);
@@ -1763,6 +1790,7 @@
 	while (state->cur <= state->last) {
 		const char *mail = am_path(state, msgnum(state));
 		int apply_status;
+		int to_keep;
 
 		reset_ident_date();
 
@@ -1792,8 +1820,29 @@
 		if (state->interactive && do_interactive(state))
 			goto next;
 
+		to_keep = 0;
+		if (is_empty_or_missing_file(am_path(state, "patch"))) {
+			switch (state->empty_type) {
+			case DROP_EMPTY_COMMIT:
+				say(state, stdout, _("Skipping: %.*s"), linelen(state->msg), state->msg);
+				goto next;
+				break;
+			case KEEP_EMPTY_COMMIT:
+				to_keep = 1;
+				say(state, stdout, _("Creating an empty commit: %.*s"),
+					linelen(state->msg), state->msg);
+				break;
+			case STOP_ON_EMPTY_COMMIT:
+				printf_ln(_("Patch is empty."));
+				die_user_resolve(state);
+				break;
+			}
+		}
+
 		if (run_applypatch_msg_hook(state))
 			exit(1);
+		if (to_keep)
+			goto commit;
 
 		say(state, stdout, _("Applying: %.*s"), linelen(state->msg), state->msg);
 
@@ -1827,6 +1876,7 @@
 			die_user_resolve(state);
 		}
 
+commit:
 		do_commit(state);
 
 next:
@@ -1856,19 +1906,24 @@
 /**
  * Resume the current am session after patch application failure. The user did
  * all the hard work, and we do not have to do any patch application. Just
- * trust and commit what the user has in the index and working tree.
+ * trust and commit what the user has in the index and working tree. If `allow_empty`
+ * is true, commit as an empty commit when index has not changed and lacking a patch.
  */
-static void am_resolve(struct am_state *state)
+static void am_resolve(struct am_state *state, int allow_empty)
 {
 	validate_resume_state(state);
 
 	say(state, stdout, _("Applying: %.*s"), linelen(state->msg), state->msg);
 
 	if (!repo_index_has_changes(the_repository, NULL, NULL)) {
-		printf_ln(_("No changes - did you forget to use 'git add'?\n"
-			"If there is nothing left to stage, chances are that something else\n"
-			"already introduced the same changes; you might want to skip this patch."));
-		die_user_resolve(state);
+		if (allow_empty && is_empty_or_missing_file(am_path(state, "patch"))) {
+			printf_ln(_("No changes - recorded it as an empty commit."));
+		} else {
+			printf_ln(_("No changes - did you forget to use 'git add'?\n"
+				    "If there is nothing left to stage, chances are that something else\n"
+				    "already introduced the same changes; you might want to skip this patch."));
+			die_user_resolve(state);
+		}
 	}
 
 	if (unmerged_cache()) {
@@ -2195,7 +2250,8 @@
 	RESUME_SKIP,
 	RESUME_ABORT,
 	RESUME_QUIT,
-	RESUME_SHOW_PATCH
+	RESUME_SHOW_PATCH,
+	RESUME_ALLOW_EMPTY,
 };
 
 struct resume_mode {
@@ -2230,9 +2286,9 @@
 	}
 
 	if (resume->mode == RESUME_SHOW_PATCH && new_value != resume->sub_mode)
-		return error(_("--show-current-patch=%s is incompatible with "
-			       "--show-current-patch=%s"),
-			     arg, valid_modes[resume->sub_mode]);
+		return error(_("options '%s=%s' and '%s=%s' "
+					   "cannot be used together"),
+					 "--show-current-patch", "--show-current-patch", arg, valid_modes[resume->sub_mode]);
 
 	resume->mode = RESUME_SHOW_PATCH;
 	resume->sub_mode = new_value;
@@ -2348,6 +2404,9 @@
 		  N_("show the patch being applied"),
 		  PARSE_OPT_CMDMODE | PARSE_OPT_OPTARG | PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP,
 		  parse_opt_show_current_patch, RESUME_SHOW_PATCH },
+		OPT_CMDMODE(0, "allow-empty", &resume.mode,
+			N_("record the empty patch as an empty commit"),
+			RESUME_ALLOW_EMPTY),
 		OPT_BOOL(0, "committer-date-is-author-date",
 			&state.committer_date_is_author_date,
 			N_("lie about committer date")),
@@ -2357,6 +2416,9 @@
 		{ OPTION_STRING, 'S', "gpg-sign", &state.sign_commit, N_("key-id"),
 		  N_("GPG-sign commits"),
 		  PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
+		OPT_CALLBACK_F(STOP_ON_EMPTY_COMMIT, "empty", &state.empty_type, "{stop,drop,keep}",
+		  N_("how to handle empty patches"),
+		  PARSE_OPT_NONEG, am_option_parse_empty),
 		OPT_HIDDEN_BOOL(0, "rebasing", &state.rebasing,
 			N_("(internal use for git-rebase)")),
 		OPT_END()
@@ -2453,7 +2515,8 @@
 		am_run(&state, 1);
 		break;
 	case RESUME_RESOLVED:
-		am_resolve(&state);
+	case RESUME_ALLOW_EMPTY:
+		am_resolve(&state, resume.mode == RESUME_ALLOW_EMPTY ? 1 : 0);
 		break;
 	case RESUME_SKIP:
 		am_skip(&state);
diff --git a/builtin/blame.c b/builtin/blame.c
index f9ee3f8..7fafeac 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -939,6 +939,9 @@
 	revs.diffopt.flags.follow_renames = 0;
 	argc = parse_options_end(&ctx);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	if (incremental || (output_option & OUTPUT_PORCELAIN)) {
 		if (show_progress > 0)
 			die(_("--progress can't be used with --incremental or porcelain formats"));
diff --git a/builtin/branch.c b/builtin/branch.c
index 7a1d1ee..2251e6a 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -77,12 +77,11 @@
 static int git_branch_config(const char *var, const char *value, void *cb)
 {
 	const char *slot_name;
-	struct ref_sorting **sorting_tail = (struct ref_sorting **)cb;
 
 	if (!strcmp(var, "branch.sort")) {
 		if (!value)
 			return config_error_nonbool(var);
-		parse_ref_sorting(sorting_tail, value);
+		string_list_append(cb, value);
 		return 0;
 	}
 
@@ -193,6 +192,7 @@
 static int delete_branches(int argc, const char **argv, int force, int kinds,
 			   int quiet)
 {
+	struct worktree **worktrees;
 	struct commit *head_rev = NULL;
 	struct object_id oid;
 	char *name = NULL;
@@ -229,6 +229,9 @@
 		if (!head_rev)
 			die(_("Couldn't look up commit object for HEAD"));
 	}
+
+	worktrees = get_worktrees();
+
 	for (i = 0; i < argc; i++, strbuf_reset(&bname)) {
 		char *target = NULL;
 		int flags = 0;
@@ -239,7 +242,7 @@
 
 		if (kinds == FILTER_REFS_BRANCHES) {
 			const struct worktree *wt =
-				find_shared_symref("HEAD", name);
+				find_shared_symref(worktrees, "HEAD", name);
 			if (wt) {
 				error(_("Cannot delete branch '%s' "
 					"checked out at '%s'"),
@@ -300,6 +303,7 @@
 
 	free(name);
 	strbuf_release(&bname);
+	free_worktrees(worktrees);
 
 	return ret;
 }
@@ -625,7 +629,8 @@
 	enum branch_track track;
 	struct ref_filter filter;
 	int icase = 0;
-	static struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
+	static struct ref_sorting *sorting;
+	struct string_list sorting_options = STRING_LIST_INIT_DUP;
 	struct ref_format format = REF_FORMAT_INIT;
 
 	struct option options[] = {
@@ -633,8 +638,10 @@
 		OPT__VERBOSE(&filter.verbose,
 			N_("show hash and subject, give twice for upstream branch")),
 		OPT__QUIET(&quiet, N_("suppress informational messages")),
-		OPT_SET_INT('t', "track",  &track, N_("set up tracking mode (see git-pull(1))"),
-			BRANCH_TRACK_EXPLICIT),
+		OPT_CALLBACK_F('t', "track",  &track, "direct|inherit",
+			N_("set branch tracking configuration"),
+			PARSE_OPT_OPTARG | PARSE_OPT_LITERAL_ARGHELP,
+			parse_opt_tracking_mode),
 		OPT_SET_INT_F(0, "set-upstream", &track, N_("do not use"),
 			BRANCH_TRACK_OVERRIDE, PARSE_OPT_HIDDEN),
 		OPT_STRING('u', "set-upstream-to", &new_upstream, N_("upstream"), N_("change the upstream info")),
@@ -666,7 +673,7 @@
 		OPT_MERGED(&filter, N_("print only branches that are merged")),
 		OPT_NO_MERGED(&filter, N_("print only branches that are not merged")),
 		OPT_COLUMN(0, "column", &colopts, N_("list branches in columns")),
-		OPT_REF_SORT(sorting_tail),
+		OPT_REF_SORT(&sorting_options),
 		OPT_CALLBACK(0, "points-at", &filter.points_at, N_("object"),
 			N_("print only branches of the object"), parse_opt_object_name),
 		OPT_BOOL('i', "ignore-case", &icase, N_("sorting and filtering are case insensitive")),
@@ -683,7 +690,7 @@
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(builtin_branch_usage, options);
 
-	git_config(git_branch_config, sorting_tail);
+	git_config(git_branch_config, &sorting_options);
 
 	track = git_branch_track;
 
@@ -717,7 +724,7 @@
 	finalize_colopts(&colopts, -1);
 	if (filter.verbose) {
 		if (explicitly_enable_column(colopts))
-			die(_("--column and --verbose are incompatible"));
+			die(_("options '%s' and '%s' cannot be used together"), "--column", "--verbose");
 		colopts = 0;
 	}
 
@@ -749,8 +756,7 @@
 		 * local branches 'refs/heads/...' and finally remote-tracking
 		 * branches 'refs/remotes/...'.
 		 */
-		if (!sorting)
-			sorting = ref_default_sorting();
+		sorting = ref_sorting_options(&sorting_options);
 		ref_sorting_set_sort_flags_all(sorting, REF_SORTING_ICASE, icase);
 		ref_sorting_set_sort_flags_all(
 			sorting, REF_SORTING_DETACHED_HEAD_FIRST, 1);
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index 86fc032..d94050e 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -729,7 +729,7 @@
 	}
 
 	if (force_path && batch.enabled) {
-		error("--path=<path> incompatible with --batch");
+		error("options '--path=<path>' and '--batch' cannot be used together");
 		usage_with_options(cat_file_usage, options);
 	}
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index cbf73b8..94814c3 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -91,8 +91,8 @@
 };
 
 struct branch_info {
-	const char *name; /* The short name used */
-	const char *path; /* The full name of a real branch */
+	char *name; /* The short name used */
+	char *path; /* The full name of a real branch */
 	struct commit *commit; /* The named commit */
 	char *refname; /* The full name of the ref being checked out. */
 	struct object_id oid; /* The object ID of the commit being checked out. */
@@ -103,6 +103,14 @@
 	char *checkout;
 };
 
+static void branch_info_release(struct branch_info *info)
+{
+	free(info->name);
+	free(info->path);
+	free(info->refname);
+	free(info->checkout);
+}
+
 static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
 			      int changed)
 {
@@ -456,10 +464,10 @@
 		die(_("'%s' cannot be used with updating paths"), "--detach");
 
 	if (opts->merge && opts->patch_mode)
-		die(_("'%s' cannot be used with %s"), "--merge", "--patch");
+		die(_("options '%s' and '%s' cannot be used together"), "--merge", "--patch");
 
 	if (opts->ignore_unmerged && opts->merge)
-		die(_("'%s' cannot be used with %s"),
+		die(_("options '%s' and '%s' cannot be used together"),
 		    opts->ignore_unmerged_opt, "-m");
 
 	if (opts->new_branch)
@@ -688,9 +696,12 @@
 		repo_get_oid_committish(the_repository, branch->name, &branch->oid);
 
 	strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
-	if (strcmp(buf.buf, branch->name))
+	if (strcmp(buf.buf, branch->name)) {
+		free(branch->name);
 		branch->name = xstrdup(buf.buf);
+	}
 	strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
+	free(branch->path);
 	branch->path = strbuf_detach(&buf, NULL);
 }
 
@@ -874,7 +885,7 @@
 				int ret;
 				struct strbuf err = STRBUF_INIT;
 
-				ret = safe_create_reflog(refname, 1, &err);
+				ret = safe_create_reflog(refname, &err);
 				if (ret) {
 					fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 						opts->new_orphan_branch, err.buf);
@@ -894,7 +905,9 @@
 				      opts->new_branch_log,
 				      opts->quiet,
 				      opts->track);
-		new_branch_info->name = opts->new_branch;
+		free(new_branch_info->name);
+		free(new_branch_info->refname);
+		new_branch_info->name = xstrdup(opts->new_branch);
 		setup_branch_path(new_branch_info);
 	}
 
@@ -1062,8 +1075,7 @@
 			   struct branch_info *new_branch_info)
 {
 	int ret = 0;
-	struct branch_info old_branch_info;
-	void *path_to_free;
+	struct branch_info old_branch_info = { 0 };
 	struct object_id rev;
 	int flag, writeout_error = 0;
 	int do_merge = 1;
@@ -1071,25 +1083,32 @@
 	trace2_cmd_mode("branch");
 
 	memset(&old_branch_info, 0, sizeof(old_branch_info));
-	old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
+	old_branch_info.path = resolve_refdup("HEAD", 0, &rev, &flag);
 	if (old_branch_info.path)
 		old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
 	if (!(flag & REF_ISSYMREF))
-		old_branch_info.path = NULL;
+		FREE_AND_NULL(old_branch_info.path);
 
-	if (old_branch_info.path)
-		skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
+	if (old_branch_info.path) {
+		const char *const prefix = "refs/heads/";
+		const char *p;
+		if (skip_prefix(old_branch_info.path, prefix, &p))
+			old_branch_info.name = xstrdup(p);
+		else
+			BUG("should be able to skip past '%s' in '%s'!",
+			    prefix, old_branch_info.path);
+	}
 
 	if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
 		if (new_branch_info->name)
 			BUG("'switch --orphan' should never accept a commit as starting point");
 		new_branch_info->commit = NULL;
-		new_branch_info->name = "(empty)";
+		new_branch_info->name = xstrdup("(empty)");
 		do_merge = 1;
 	}
 
 	if (!new_branch_info->name) {
-		new_branch_info->name = "HEAD";
+		new_branch_info->name = xstrdup("HEAD");
 		new_branch_info->commit = old_branch_info.commit;
 		if (!new_branch_info->commit)
 			die(_("You are on a branch yet to be born"));
@@ -1102,7 +1121,7 @@
 	if (do_merge) {
 		ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 		if (ret) {
-			free(path_to_free);
+			branch_info_release(&old_branch_info);
 			return ret;
 		}
 	}
@@ -1113,7 +1132,8 @@
 	update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 
 	ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
-	free(path_to_free);
+	branch_info_release(&old_branch_info);
+
 	return ret || writeout_error;
 }
 
@@ -1145,16 +1165,15 @@
 	struct tree **source_tree = &opts->source_tree;
 	struct object_id branch_rev;
 
-	new_branch_info->name = arg;
+	new_branch_info->name = xstrdup(arg);
 	setup_branch_path(new_branch_info);
 
 	if (!check_refname_format(new_branch_info->path, 0) &&
 	    !read_ref(new_branch_info->path, &branch_rev))
 		oidcpy(rev, &branch_rev);
-	else {
-		free((char *)new_branch_info->path);
-		new_branch_info->path = NULL; /* not an existing branch */
-	}
+	else
+		/* not an existing branch */
+		FREE_AND_NULL(new_branch_info->path);
 
 	new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
 	if (!new_branch_info->commit) {
@@ -1517,7 +1536,7 @@
 		OPT_BOOL(0, "progress", &opts->show_progress, N_("force progress reporting")),
 		OPT_BOOL('m', "merge", &opts->merge, N_("perform a 3-way merge with the new branch")),
 		OPT_STRING(0, "conflict", &opts->conflict_style, N_("style"),
-			   N_("conflict style (merge or diff3)")),
+			   N_("conflict style (merge, diff3, or zdiff3)")),
 		OPT_END()
 	};
 	struct option *newopts = parse_options_concat(prevopts, options);
@@ -1530,8 +1549,10 @@
 {
 	struct option options[] = {
 		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
-		OPT_SET_INT('t', "track",  &opts->track, N_("set upstream info for new branch"),
-			BRANCH_TRACK_EXPLICIT),
+		OPT_CALLBACK_F('t', "track",  &opts->track, "direct|inherit",
+			N_("set up tracking mode (see git-pull(1))"),
+			PARSE_OPT_OPTARG | PARSE_OPT_LITERAL_ARGHELP,
+			parse_opt_tracking_mode),
 		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
@@ -1574,12 +1595,11 @@
 
 static int checkout_main(int argc, const char **argv, const char *prefix,
 			 struct checkout_opts *opts, struct option *options,
-			 const char * const usagestr[])
+			 const char * const usagestr[],
+			 struct branch_info *new_branch_info)
 {
-	struct branch_info new_branch_info;
 	int parseopt_flags = 0;
 
-	memset(&new_branch_info, 0, sizeof(new_branch_info));
 	opts->overwrite_ignore = 1;
 	opts->prefix = prefix;
 	opts->show_progress = -1;
@@ -1617,11 +1637,11 @@
 	}
 
 	if ((!!opts->new_branch + !!opts->new_branch_force + !!opts->new_orphan_branch) > 1)
-		die(_("-%c, -%c and --orphan are mutually exclusive"),
-				cb_option, toupper(cb_option));
+		die(_("options '-%c', '-%c', and '%s' cannot be used together"),
+			cb_option, toupper(cb_option), "--orphan");
 
 	if (opts->overlay_mode == 1 && opts->patch_mode)
-		die(_("-p and --overlay are mutually exclusive"));
+		die(_("options '%s' and '%s' cannot be used together"), "-p", "--overlay");
 
 	if (opts->checkout_index >= 0 || opts->checkout_worktree >= 0) {
 		if (opts->checkout_index < 0)
@@ -1688,7 +1708,7 @@
 			opts->track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts->new_branch;
 		int n = parse_branchname_arg(argc, argv, dwim_ok,
-					     &new_branch_info, opts, &rev);
+					     new_branch_info, opts, &rev);
 		argv += n;
 		argc -= n;
 	} else if (!opts->accept_ref && opts->from_treeish) {
@@ -1697,7 +1717,7 @@
 		if (get_oid_mb(opts->from_treeish, &rev))
 			die(_("could not resolve %s"), opts->from_treeish);
 
-		setup_new_branch_info_and_source_tree(&new_branch_info,
+		setup_new_branch_info_and_source_tree(new_branch_info,
 						      opts, &rev,
 						      opts->from_treeish);
 
@@ -1717,7 +1737,7 @@
 		 * Try to give more helpful suggestion.
 		 * new_branch && argc > 1 will be caught later.
 		 */
-		if (opts->new_branch && argc == 1 && !new_branch_info.commit)
+		if (opts->new_branch && argc == 1 && !new_branch_info->commit)
 			die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
 				argv[0], opts->new_branch);
 
@@ -1728,19 +1748,19 @@
 
 	if (opts->pathspec_from_file) {
 		if (opts->pathspec.nr)
-			die(_("--pathspec-from-file is incompatible with pathspec arguments"));
+			die(_("'%s' and pathspec arguments cannot be used together"), "--pathspec-from-file");
 
 		if (opts->force_detach)
-			die(_("--pathspec-from-file is incompatible with --detach"));
+			die(_("options '%s' and '%s' cannot be used together"), "--pathspec-from-file", "--detach");
 
 		if (opts->patch_mode)
-			die(_("--pathspec-from-file is incompatible with --patch"));
+			die(_("options '%s' and '%s' cannot be used together"), "--pathspec-from-file", "--patch");
 
 		parse_pathspec_file(&opts->pathspec, 0,
 				    0,
 				    prefix, opts->pathspec_from_file, opts->pathspec_file_nul);
 	} else if (opts->pathspec_file_nul) {
-		die(_("--pathspec-file-nul requires --pathspec-from-file"));
+		die(_("the option '%s' requires '%s'"), "--pathspec-file-nul", "--pathspec-from-file");
 	}
 
 	opts->pathspec.recursive = 1;
@@ -1766,11 +1786,10 @@
 		strbuf_release(&buf);
 	}
 
-	UNLEAK(opts);
 	if (opts->patch_mode || opts->pathspec.nr)
-		return checkout_paths(opts, &new_branch_info);
+		return checkout_paths(opts, new_branch_info);
 	else
-		return checkout_branch(opts, &new_branch_info);
+		return checkout_branch(opts, new_branch_info);
 }
 
 int cmd_checkout(int argc, const char **argv, const char *prefix)
@@ -1789,6 +1808,7 @@
 		OPT_END()
 	};
 	int ret;
+	struct branch_info new_branch_info = { 0 };
 
 	memset(&opts, 0, sizeof(opts));
 	opts.dwim_new_local_branch = 1;
@@ -1819,7 +1839,9 @@
 	options = add_checkout_path_options(&opts, options);
 
 	ret = checkout_main(argc, argv, prefix, &opts,
-			    options, checkout_usage);
+			    options, checkout_usage, &new_branch_info);
+	branch_info_release(&new_branch_info);
+	clear_pathspec(&opts.pathspec);
 	FREE_AND_NULL(options);
 	return ret;
 }
@@ -1840,6 +1862,7 @@
 		OPT_END()
 	};
 	int ret;
+	struct branch_info new_branch_info = { 0 };
 
 	memset(&opts, 0, sizeof(opts));
 	opts.dwim_new_local_branch = 1;
@@ -1859,7 +1882,8 @@
 	cb_option = 'c';
 
 	ret = checkout_main(argc, argv, prefix, &opts,
-			    options, switch_branch_usage);
+			    options, switch_branch_usage, &new_branch_info);
+	branch_info_release(&new_branch_info);
 	FREE_AND_NULL(options);
 	return ret;
 }
@@ -1881,6 +1905,7 @@
 		OPT_END()
 	};
 	int ret;
+	struct branch_info new_branch_info = { 0 };
 
 	memset(&opts, 0, sizeof(opts));
 	opts.accept_ref = 0;
@@ -1896,7 +1921,8 @@
 	options = add_checkout_path_options(&opts, options);
 
 	ret = checkout_main(argc, argv, prefix, &opts,
-			    options, restore_usage);
+			    options, restore_usage, &new_branch_info);
+	branch_info_release(&new_branch_info);
 	FREE_AND_NULL(options);
 	return ret;
 }
diff --git a/builtin/clean.c b/builtin/clean.c
index 98a2860..3ff02bb 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -36,6 +36,8 @@
 static const char *msg_would_skip_git_dir = N_("Would skip repository %s\n");
 static const char *msg_warn_remove_failed = N_("failed to remove %s");
 static const char *msg_warn_lstat_failed = N_("could not lstat %s\n");
+static const char *msg_skip_cwd = N_("Refusing to remove current working directory\n");
+static const char *msg_would_skip_cwd = N_("Would refuse to remove current working directory\n");
 
 enum color_clean {
 	CLEAN_COLOR_RESET = 0,
@@ -153,6 +155,8 @@
 {
 	DIR *dir;
 	struct strbuf quoted = STRBUF_INIT;
+	struct strbuf realpath = STRBUF_INIT;
+	struct strbuf real_ocwd = STRBUF_INIT;
 	struct dirent *e;
 	int res = 0, ret = 0, gone = 1, original_len = path->len, len;
 	struct string_list dels = STRING_LIST_INIT_DUP;
@@ -231,16 +235,36 @@
 	strbuf_setlen(path, original_len);
 
 	if (*dir_gone) {
-		res = dry_run ? 0 : rmdir(path->buf);
-		if (!res)
-			*dir_gone = 1;
-		else {
-			int saved_errno = errno;
-			quote_path(path->buf, prefix, &quoted, 0);
-			errno = saved_errno;
-			warning_errno(_(msg_warn_remove_failed), quoted.buf);
+		/*
+		 * Normalize path components in path->buf, e.g. change '\' to
+		 * '/' on Windows.
+		 */
+		strbuf_realpath(&realpath, path->buf, 1);
+
+		/*
+		 * path and realpath are absolute; for comparison, we would
+		 * like to transform startup_info->original_cwd to an absolute
+		 * path too.
+		 */
+		 if (startup_info->original_cwd)
+			 strbuf_realpath(&real_ocwd,
+					 startup_info->original_cwd, 1);
+
+		if (!strbuf_cmp(&realpath, &real_ocwd)) {
+			printf("%s", dry_run ? _(msg_would_skip_cwd) : _(msg_skip_cwd));
 			*dir_gone = 0;
-			ret = 1;
+		} else {
+			res = dry_run ? 0 : rmdir(path->buf);
+			if (!res)
+				*dir_gone = 1;
+			else {
+				int saved_errno = errno;
+				quote_path(path->buf, prefix, &quoted, 0);
+				errno = saved_errno;
+				warning_errno(_(msg_warn_remove_failed), quoted.buf);
+				*dir_gone = 0;
+				ret = 1;
+			}
 		}
 	}
 
@@ -250,6 +274,8 @@
 			printf(dry_run ?  _(msg_would_remove) : _(msg_remove), dels.items[i].string);
 	}
 out:
+	strbuf_release(&realpath);
+	strbuf_release(&real_ocwd);
 	strbuf_release(&quoted);
 	string_list_clear(&dels, 0);
 	return ret;
diff --git a/builtin/clone.c b/builtin/clone.c
index fb377b2..727e16e 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -633,7 +633,7 @@
 {
 	struct strvec argv = STRVEC_INIT;
 	int result = 0;
-	strvec_pushl(&argv, "-C", repo, "sparse-checkout", "init", NULL);
+	strvec_pushl(&argv, "-C", repo, "sparse-checkout", "set", NULL);
 
 	/*
 	 * We must apply the setting in the current process
@@ -900,10 +900,10 @@
 
 	if (option_bare) {
 		if (option_origin)
-			die(_("--bare and --origin %s options are incompatible."),
-			    option_origin);
+			die(_("options '%s' and '%s %s' cannot be used together"),
+			    "--bare", "--origin", option_origin);
 		if (real_git_dir)
-			die(_("--bare and --separate-git-dir are incompatible."));
+			die(_("options '%s' and '%s' cannot be used together"), "--bare", "--separate-git-dir");
 		option_no_checkout = 1;
 	}
 
@@ -1290,7 +1290,7 @@
 	 */
 	submodule_progress = transport->progress;
 
-	transport_unlock_pack(transport);
+	transport_unlock_pack(transport, 0);
 	transport_disconnect(transport);
 
 	if (option_dissociate) {
diff --git a/builtin/commit.c b/builtin/commit.c
index 883c162..b9ed037 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -355,19 +355,19 @@
 
 	if (pathspec_from_file) {
 		if (interactive)
-			die(_("--pathspec-from-file is incompatible with --interactive/--patch"));
+			die(_("options '%s' and '%s' cannot be used together"), "--pathspec-from-file", "--interactive/--patch");
 
 		if (all)
-			die(_("--pathspec-from-file with -a does not make sense"));
+			die(_("options '%s' and '%s' cannot be used together"), "--pathspec-from-file", "-a");
 
 		if (pathspec.nr)
-			die(_("--pathspec-from-file is incompatible with pathspec arguments"));
+			die(_("'%s' and pathspec arguments cannot be used together"), "--pathspec-from-file");
 
 		parse_pathspec_file(&pathspec, 0,
 				    PATHSPEC_PREFER_FULL,
 				    prefix, pathspec_from_file, pathspec_file_nul);
 	} else if (pathspec_file_nul) {
-		die(_("--pathspec-file-nul requires --pathspec-from-file"));
+		die(_("the option '%s' requires '%s'"), "--pathspec-file-nul", "--pathspec-from-file");
 	}
 
 	if (!pathspec.nr && (also || (only && !allow_empty &&
@@ -799,7 +799,7 @@
 
 		if (!strcmp(fixup_prefix, "amend")) {
 			if (have_option_m)
-				die(_("cannot combine -m with --fixup:%s"), fixup_message);
+				die(_("options '%s' and '%s:%s' cannot be used together"), "-m", "--fixup", fixup_message);
 			prepare_amend_commit(commit, &sb, &ctx);
 		}
 	} else if (!stat(git_path_merge_msg(the_repository), &statbuf)) {
@@ -1193,7 +1193,7 @@
 		    status_format == STATUS_FORMAT_UNSPECIFIED)
 			status_format = STATUS_FORMAT_PORCELAIN;
 		else if (status_format == STATUS_FORMAT_LONG)
-			die(_("--long and -z are incompatible"));
+			die(_("options '%s' and '%s' cannot be used together"), "--long", "-z");
 	}
 
 	if (use_deferred_config && status_format == STATUS_FORMAT_UNSPECIFIED)
@@ -1229,9 +1229,10 @@
 			die(_("You are in the middle of a cherry-pick -- cannot reword."));
 	}
 	if (argc)
-		die(_("cannot combine reword option of --fixup with path '%s'"), *argv);
+		die(_("reword option of '%s' and path '%s' cannot be used together"), "--fixup", *argv);
 	if (patch_interactive || interactive || all || also || only)
-		die(_("reword option of --fixup is mutually exclusive with --patch/--interactive/--all/--include/--only"));
+		die(_("reword option of '%s' and '%s' cannot be used together"),
+			"--fixup", "--patch/--interactive/--all/--include/--only");
 }
 
 static int parse_and_validate_options(int argc, const char *argv[],
diff --git a/builtin/credential.c b/builtin/credential.c
index d75dcdc..d7b304f 100644
--- a/builtin/credential.c
+++ b/builtin/credential.c
@@ -4,7 +4,7 @@
 #include "config.h"
 
 static const char usage_msg[] =
-	"git credential [fill|approve|reject]";
+	"git credential (fill|approve|reject)";
 
 int cmd_credential(int argc, const char **argv, const char *prefix)
 {
diff --git a/builtin/describe.c b/builtin/describe.c
index e912ba5..42159cd 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -590,7 +590,7 @@
 	save_commit_buffer = 0;
 
 	if (longformat && abbrev == 0)
-		die(_("--long is incompatible with --abbrev=0"));
+		die(_("options '%s' and '%s' cannot be used together"), "--long", "--abbrev=0");
 
 	if (contains) {
 		struct string_list_item *item;
@@ -670,9 +670,9 @@
 		}
 		describe("HEAD", 1);
 	} else if (dirty) {
-		die(_("--dirty is incompatible with commit-ishes"));
+		die(_("option '%s' and commit-ishes cannot be used together"), "--dirty");
 	} else if (broken) {
-		die(_("--broken is incompatible with commit-ishes"));
+		die(_("option '%s' and commit-ishes cannot be used together"), "--broken");
 	} else {
 		while (argc-- > 0)
 			describe(*argv++, argc == 0);
diff --git a/builtin/diff-tree.c b/builtin/diff-tree.c
index f33d30d..0e0ac1f 100644
--- a/builtin/diff-tree.c
+++ b/builtin/diff-tree.c
@@ -152,7 +152,7 @@
 	}
 
 	if (read_stdin && merge_base)
-		die(_("--stdin and --merge-base are mutually exclusive"));
+		die(_("options '%s' and '%s' cannot be used together"), "--stdin", "--merge-base");
 	if (merge_base && opt->pending.nr != 2)
 		die(_("--merge-base only works with two commits"));
 
diff --git a/builtin/diff.c b/builtin/diff.c
index dd8ce68..fa46833 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -437,6 +437,11 @@
 
 	prefix = setup_git_directory_gently(&nongit);
 
+	if (!nongit) {
+		prepare_repo_settings(the_repository);
+		the_repository->settings.command_requires_full_index = 0;
+	}
+
 	if (!no_index) {
 		/*
 		 * Treat git diff with at least one path outside of the
diff --git a/builtin/difftool.c b/builtin/difftool.c
index 4931c10..c79fbbf 100644
--- a/builtin/difftool.c
+++ b/builtin/difftool.c
@@ -202,15 +202,10 @@
 {
 	struct child_process update_index = CHILD_PROCESS_INIT;
 	struct child_process diff_files = CHILD_PROCESS_INIT;
-	struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
-	const char *git_dir = absolute_path(get_git_dir()), *env[] = {
-		NULL, NULL
-	};
+	struct strbuf buf = STRBUF_INIT;
+	const char *git_dir = absolute_path(get_git_dir());
 	FILE *fp;
 
-	strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
-	env[0] = index_env.buf;
-
 	strvec_pushl(&update_index.args,
 		     "--git-dir", git_dir, "--work-tree", workdir,
 		     "update-index", "--really-refresh", "-q",
@@ -222,7 +217,7 @@
 	update_index.use_shell = 0;
 	update_index.clean_on_exit = 1;
 	update_index.dir = workdir;
-	update_index.env = env;
+	strvec_pushf(&update_index.env_array, "GIT_INDEX_FILE=%s", index_path);
 	/* Ignore any errors of update-index */
 	run_command(&update_index);
 
@@ -235,7 +230,7 @@
 	diff_files.clean_on_exit = 1;
 	diff_files.out = -1;
 	diff_files.dir = workdir;
-	diff_files.env = env;
+	strvec_pushf(&diff_files.env_array, "GIT_INDEX_FILE=%s", index_path);
 	if (start_command(&diff_files))
 		die("could not obtain raw diff");
 	fp = xfdopen(diff_files.out, "r");
@@ -248,7 +243,6 @@
 	fclose(fp);
 	if (finish_command(&diff_files))
 		die("diff-files did not exit properly");
-	strbuf_release(&index_env);
 	strbuf_release(&buf);
 }
 
@@ -736,10 +730,10 @@
 		setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
 		setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
 	} else if (dir_diff)
-		die(_("--dir-diff is incompatible with --no-index"));
+		die(_("options '%s' and '%s' cannot be used together"), "--dir-diff", "--no-index");
 
 	if (use_gui_tool + !!difftool_cmd + !!extcmd > 1)
-		die(_("--gui, --tool and --extcmd are mutually exclusive"));
+		die(_("options '%s', '%s', and '%s' cannot be used together"), "--gui", "--tool", "--extcmd");
 
 	if (use_gui_tool)
 		setenv("GIT_MERGETOOL_GUI", "true", 1);
diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 8e2caf7..9f1c730 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -107,18 +107,6 @@
 
 static struct decoration idnums;
 static uint32_t last_idnum;
-
-static int has_unshown_parent(struct commit *commit)
-{
-	struct commit_list *parent;
-
-	for (parent = commit->parents; parent; parent = parent->next)
-		if (!(parent->item->object.flags & SHOWN) &&
-		    !(parent->item->object.flags & UNINTERESTING))
-			return 1;
-	return 0;
-}
-
 struct anonymized_entry {
 	struct hashmap_entry hash;
 	const char *anon;
@@ -752,20 +740,6 @@
 	return strbuf_detach(&out, NULL);
 }
 
-static void handle_tail(struct object_array *commits, struct rev_info *revs,
-			struct string_list *paths_of_changed_objects)
-{
-	struct commit *commit;
-	while (commits->nr) {
-		commit = (struct commit *)object_array_pop(commits);
-		if (has_unshown_parent(commit)) {
-			/* Queue again, to be handled later */
-			add_object_array(&commit->object, NULL, commits);
-			return;
-		}
-		handle_commit(commit, revs, paths_of_changed_objects);
-	}
-}
 
 static void handle_tag(const char *name, struct tag *tag)
 {
@@ -1185,7 +1159,6 @@
 int cmd_fast_export(int argc, const char **argv, const char *prefix)
 {
 	struct rev_info revs;
-	struct object_array commits = OBJECT_ARRAY_INIT;
 	struct commit *commit;
 	char *export_filename = NULL,
 	     *import_filename = NULL,
@@ -1254,7 +1227,7 @@
 		usage_with_options (fast_export_usage, options);
 
 	if (anonymized_seeds.cmpfn && !anonymize)
-		die(_("--anonymize-map without --anonymize does not make sense"));
+		die(_("the option '%s' requires '%s'"), "--anonymize-map", "--anonymize");
 
 	if (refspecs_list.nr) {
 		int i;
@@ -1269,7 +1242,7 @@
 		printf("feature done\n");
 
 	if (import_filename && import_filename_if_exists)
-		die(_("Cannot pass both --import-marks and --import-marks-if-exists"));
+		die(_("options '%s' and '%s' cannot be used together"), "--import-marks", "--import-marks-if-exists");
 	if (import_filename)
 		import_marks(import_filename, 0);
 	else if (import_filename_if_exists)
@@ -1283,18 +1256,13 @@
 
 	if (prepare_revision_walk(&revs))
 		die("revision walk setup failed");
+
+	revs.reverse = 1;
 	revs.diffopt.format_callback = show_filemodify;
 	revs.diffopt.format_callback_data = &paths_of_changed_objects;
 	revs.diffopt.flags.recursive = 1;
-	while ((commit = get_revision(&revs))) {
-		if (has_unshown_parent(commit)) {
-			add_object_array(&commit->object, NULL, &commits);
-		}
-		else {
-			handle_commit(commit, &revs, &paths_of_changed_objects);
-			handle_tail(&commits, &revs, &paths_of_changed_objects);
-		}
-	}
+	while ((commit = get_revision(&revs)))
+		handle_commit(commit, &revs, &paths_of_changed_objects);
 
 	handle_tags_and_duplicates(&extra_refs);
 	handle_tags_and_duplicates(&tag_refs);
diff --git a/builtin/fast-import.c b/builtin/fast-import.c
index 20406f6..2b2e28b 100644
--- a/builtin/fast-import.c
+++ b/builtin/fast-import.c
@@ -401,16 +401,18 @@
 
 static NORETURN void die_nicely(const char *err, va_list params)
 {
+	va_list cp;
 	static int zombie;
-	char message[2 * PATH_MAX];
+	report_fn die_message_fn = get_die_message_routine();
 
-	vsnprintf(message, sizeof(message), err, params);
-	fputs("fatal: ", stderr);
-	fputs(message, stderr);
-	fputc('\n', stderr);
+	va_copy(cp, params);
+	die_message_fn(err, params);
 
 	if (!zombie) {
+		char message[2 * PATH_MAX];
+
 		zombie = 1;
+		vsnprintf(message, sizeof(message), err, cp);
 		write_crash_report(message);
 		end_packfile();
 		unkeep_all_packs();
diff --git a/builtin/fetch.c b/builtin/fetch.c
index f7abbc3..5f06b21 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -28,6 +28,7 @@
 #include "promisor-remote.h"
 #include "commit-graph.h"
 #include "shallow.h"
+#include "worktree.h"
 
 #define FORCED_UPDATES_DELAY_WARNING_IN_MS (10 * 1000)
 
@@ -222,17 +223,22 @@
 	OPT_END()
 };
 
-static void unlock_pack(void)
+static void unlock_pack(unsigned int flags)
 {
 	if (gtransport)
-		transport_unlock_pack(gtransport);
+		transport_unlock_pack(gtransport, flags);
 	if (gsecondary)
-		transport_unlock_pack(gsecondary);
+		transport_unlock_pack(gsecondary, flags);
+}
+
+static void unlock_pack_atexit(void)
+{
+	unlock_pack(0);
 }
 
 static void unlock_pack_on_signal(int signo)
 {
-	unlock_pack();
+	unlock_pack(TRANSPORT_UNLOCK_PACK_IN_SIGNAL_HANDLER);
 	sigchain_pop(signo);
 	raise(signo);
 }
@@ -552,7 +558,7 @@
 		for (i = 0; i < fetch_refspec->nr; i++)
 			get_fetch_map(ref_map, &fetch_refspec->items[i], &oref_tail, 1);
 	} else if (refmap.nr) {
-		die("--refmap option is only meaningful with command-line refspec(s).");
+		die("--refmap option is only meaningful with command-line refspec(s)");
 	} else {
 		/* Use the defaults */
 		struct branch *branch = branch_get(NULL);
@@ -583,7 +589,7 @@
 		} else if (!prefetch) {
 			ref_map = get_remote_ref(remote_refs, "HEAD");
 			if (!ref_map)
-				die(_("Couldn't find remote ref HEAD"));
+				die(_("couldn't find remote ref HEAD"));
 			ref_map->fetch_head_status = FETCH_HEAD_MERGE;
 			tail = &ref_map->next;
 		}
@@ -848,13 +854,12 @@
 
 static int update_local_ref(struct ref *ref,
 			    struct ref_transaction *transaction,
-			    const char *remote,
-			    const struct ref *remote_ref,
-			    struct strbuf *display,
-			    int summary_width)
+			    const char *remote, const struct ref *remote_ref,
+			    struct strbuf *display, int summary_width,
+			    struct worktree **worktrees)
 {
 	struct commit *current = NULL, *updated;
-	struct branch *current_branch = branch_get(NULL);
+	const struct worktree *wt;
 	const char *pretty_ref = prettify_refname(ref->name);
 	int fast_forward = 0;
 
@@ -868,16 +873,17 @@
 		return 0;
 	}
 
-	if (current_branch &&
-	    !strcmp(ref->name, current_branch->name) &&
-	    !(update_head_ok || is_bare_repository()) &&
-	    !is_null_oid(&ref->old_oid)) {
+	if (!update_head_ok &&
+	    (wt = find_shared_symref(worktrees, "HEAD", ref->name)) &&
+	    !wt->is_bare && !is_null_oid(&ref->old_oid)) {
 		/*
 		 * If this is the head, and it's not okay to update
 		 * the head, and the old value of the head isn't empty...
 		 */
 		format_display(display, '!', _("[rejected]"),
-			       _("can't fetch in current branch"),
+			       wt->is_current ?
+				       _("can't fetch in current branch") :
+				       _("checked out in another worktree"),
 			       remote, pretty_ref, summary_width);
 		return 1;
 	}
@@ -995,7 +1001,7 @@
 	if (write_fetch_head) {
 		fetch_head->fp = fopen(filename, "a");
 		if (!fetch_head->fp)
-			return error_errno(_("cannot open %s"), filename);
+			return error_errno(_("cannot open '%s'"), filename);
 		strbuf_init(&fetch_head->buf, 0);
 	} else {
 		fetch_head->fp = NULL;
@@ -1067,16 +1073,17 @@
 }
 
 static const char warn_show_forced_updates[] =
-N_("Fetch normally indicates which branches had a forced update,\n"
-   "but that check has been disabled. To re-enable, use '--show-forced-updates'\n"
-   "flag or run 'git config fetch.showForcedUpdates true'.");
+N_("fetch normally indicates which branches had a forced update,\n"
+   "but that check has been disabled; to re-enable, use '--show-forced-updates'\n"
+   "flag or run 'git config fetch.showForcedUpdates true'");
 static const char warn_time_show_forced_updates[] =
-N_("It took %.2f seconds to check forced updates. You can use\n"
+N_("it took %.2f seconds to check forced updates; you can use\n"
    "'--no-show-forced-updates' or run 'git config fetch.showForcedUpdates false'\n"
-   " to avoid this check.\n");
+   "to avoid this check\n");
 
 static int store_updated_refs(const char *raw_url, const char *remote_name,
-			      int connectivity_checked, struct ref *ref_map)
+			      int connectivity_checked, struct ref *ref_map,
+			      struct worktree **worktrees)
 {
 	struct fetch_head fetch_head;
 	int url_len, i, rc = 0;
@@ -1205,7 +1212,8 @@
 			strbuf_reset(&note);
 			if (ref) {
 				rc |= update_local_ref(ref, transaction, what,
-						       rm, &note, summary_width);
+						       rm, &note, summary_width,
+						       worktrees);
 				free(ref);
 			} else if (write_fetch_head || dry_run) {
 				/*
@@ -1298,7 +1306,9 @@
 	return check_connected(iterate_ref_map, &rm, &opt);
 }
 
-static int fetch_and_consume_refs(struct transport *transport, struct ref *ref_map)
+static int fetch_and_consume_refs(struct transport *transport,
+				  struct ref *ref_map,
+				  struct worktree **worktrees)
 {
 	int connectivity_checked = 1;
 	int ret;
@@ -1319,14 +1329,12 @@
 	}
 
 	trace2_region_enter("fetch", "consume_refs", the_repository);
-	ret = store_updated_refs(transport->url,
-				 transport->remote->name,
-				 connectivity_checked,
-				 ref_map);
+	ret = store_updated_refs(transport->url, transport->remote->name,
+				 connectivity_checked, ref_map, worktrees);
 	trace2_region_leave("fetch", "consume_refs", the_repository);
 
 out:
-	transport_unlock_pack(transport);
+	transport_unlock_pack(transport, 0);
 	return ret;
 }
 
@@ -1385,18 +1393,18 @@
 	return result;
 }
 
-static void check_not_current_branch(struct ref *ref_map)
+static void check_not_current_branch(struct ref *ref_map,
+				     struct worktree **worktrees)
 {
-	struct branch *current_branch = branch_get(NULL);
-
-	if (is_bare_repository() || !current_branch)
-		return;
-
+	const struct worktree *wt;
 	for (; ref_map; ref_map = ref_map->next)
-		if (ref_map->peer_ref && !strcmp(current_branch->refname,
-					ref_map->peer_ref->name))
-			die(_("Refusing to fetch into current branch %s "
-			    "of non-bare repository"), current_branch->refname);
+		if (ref_map->peer_ref &&
+		    (wt = find_shared_symref(worktrees, "HEAD",
+					     ref_map->peer_ref->name)) &&
+		    !wt->is_bare)
+			die(_("refusing to fetch into branch '%s' "
+			      "checked out at '%s'"),
+			    ref_map->peer_ref->name, wt->path);
 }
 
 static int truncate_fetch_head(void)
@@ -1405,7 +1413,7 @@
 	FILE *fp = fopen_for_writing(filename);
 
 	if (!fp)
-		return error_errno(_("cannot open %s"), filename);
+		return error_errno(_("cannot open '%s'"), filename);
 	fclose(fp);
 	return 0;
 }
@@ -1414,10 +1422,10 @@
 {
 	int r = transport_set_option(transport, name, value);
 	if (r < 0)
-		die(_("Option \"%s\" value \"%s\" is not valid for %s"),
+		die(_("option \"%s\" value \"%s\" is not valid for %s"),
 		    name, value, transport->url);
 	if (r > 0)
-		warning(_("Option \"%s\" is ignored for %s\n"),
+		warning(_("option \"%s\" is ignored for %s\n"),
 			name, transport->url);
 }
 
@@ -1451,7 +1459,7 @@
 		old_nr = oids->nr;
 		for_each_glob_ref(add_oid, s, oids);
 		if (old_nr == oids->nr)
-			warning("Ignoring --negotiation-tip=%s because it does not match any refs",
+			warning("ignoring --negotiation-tip=%s because it does not match any refs",
 				s);
 	}
 	smart_options->negotiation_tips = oids;
@@ -1489,12 +1497,13 @@
 		if (transport->smart_options)
 			add_negotiation_tips(transport->smart_options);
 		else
-			warning("Ignoring --negotiation-tip because the protocol does not support it.");
+			warning("ignoring --negotiation-tip because the protocol does not support it");
 	}
 	return transport;
 }
 
-static void backfill_tags(struct transport *transport, struct ref *ref_map)
+static void backfill_tags(struct transport *transport, struct ref *ref_map,
+			  struct worktree **worktrees)
 {
 	int cannot_reuse;
 
@@ -1515,7 +1524,7 @@
 	transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, NULL);
 	transport_set_option(transport, TRANS_OPT_DEPTH, "0");
 	transport_set_option(transport, TRANS_OPT_DEEPEN_RELATIVE, NULL);
-	fetch_and_consume_refs(transport, ref_map);
+	fetch_and_consume_refs(transport, ref_map, worktrees);
 
 	if (gsecondary) {
 		transport_disconnect(gsecondary);
@@ -1533,6 +1542,7 @@
 	struct transport_ls_refs_options transport_ls_refs_options =
 		TRANSPORT_LS_REFS_OPTIONS_INIT;
 	int must_list_refs = 1;
+	struct worktree **worktrees = get_worktrees();
 
 	if (tags == TAGS_DEFAULT) {
 		if (transport->remote->fetch_tags == 2)
@@ -1588,7 +1598,7 @@
 	ref_map = get_ref_map(transport->remote, remote_refs, rs,
 			      tags, &autotags);
 	if (!update_head_ok)
-		check_not_current_branch(ref_map);
+		check_not_current_branch(ref_map, worktrees);
 
 	if (tags == TAGS_DEFAULT && autotags)
 		transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");
@@ -1606,7 +1616,7 @@
 				   transport->url);
 		}
 	}
-	if (fetch_and_consume_refs(transport, ref_map)) {
+	if (fetch_and_consume_refs(transport, ref_map, worktrees)) {
 		free_refs(ref_map);
 		retcode = 1;
 		goto cleanup;
@@ -1638,6 +1648,16 @@
 			}
 		}
 		if (source_ref) {
+			if (!branch) {
+				const char *shortname = source_ref->name;
+				skip_prefix(shortname, "refs/heads/", &shortname);
+
+				warning(_("could not set upstream of HEAD to '%s' from '%s' when "
+					  "it does not point to any branch."),
+					shortname, transport->remote->name);
+				goto skip;
+			}
+
 			if (!strcmp(source_ref->name, "HEAD") ||
 			    starts_with(source_ref->name, "refs/heads/"))
 				install_branch_config(0,
@@ -1651,11 +1671,11 @@
 			else
 				warning(_("unknown branch type"));
 		} else {
-			warning(_("no source branch found.\n"
-				"you need to specify exactly one branch with the --set-upstream option."));
+			warning(_("no source branch found;\n"
+				  "you need to specify exactly one branch with the --set-upstream option"));
 		}
 	}
- skip:
+skip:
 	free_refs(ref_map);
 
 	/* if neither --no-tags nor --tags was specified, do automated tag
@@ -1665,11 +1685,12 @@
 		ref_map = NULL;
 		find_non_local_tags(remote_refs, &ref_map, &tail);
 		if (ref_map)
-			backfill_tags(transport, ref_map);
+			backfill_tags(transport, ref_map, worktrees);
 		free_refs(ref_map);
 	}
 
- cleanup:
+cleanup:
+	free_worktrees(worktrees);
 	return retcode;
 }
 
@@ -1790,7 +1811,7 @@
 	struct parallel_fetch_state *state = cb;
 	const char *remote = task_cb;
 
-	state->result = error(_("Could not fetch %s"), remote);
+	state->result = error(_("could not fetch %s"), remote);
 
 	return 0;
 }
@@ -1845,7 +1866,7 @@
 			if (verbosity >= 0)
 				printf(_("Fetching %s\n"), name);
 			if (run_command_v_opt(argv.v, RUN_GIT_CMD)) {
-				error(_("Could not fetch %s"), name);
+				error(_("could not fetch %s"), name);
 				result = 1;
 			}
 			strvec_pop(&argv);
@@ -1906,8 +1927,8 @@
 	int remote_via_config = remote_is_configured(remote, 0);
 
 	if (!remote)
-		die(_("No remote repository specified.  Please, specify either a URL or a\n"
-		    "remote name from which new revisions should be fetched."));
+		die(_("no remote repository specified; please specify either a URL or a\n"
+		      "remote name from which new revisions should be fetched"));
 
 	gtransport = prepare_transport(remote, 1);
 
@@ -1942,7 +1963,7 @@
 		if (!strcmp(argv[i], "tag")) {
 			i++;
 			if (i >= argc)
-				die(_("You need to specify a tag name."));
+				die(_("you need to specify a tag name"));
 
 			refspec_appendf(&rs, "refs/tags/%s:refs/tags/%s",
 					argv[i], argv[i]);
@@ -1962,7 +1983,7 @@
 		gtransport->server_options = &server_options;
 
 	sigchain_push_common(unlock_pack_on_signal);
-	atexit(unlock_pack);
+	atexit(unlock_pack_atexit);
 	sigchain_push(SIGPIPE, SIG_IGN);
 	exit_code = do_fetch(gtransport, &rs);
 	sigchain_pop(SIGPIPE);
@@ -1993,6 +2014,8 @@
 	}
 
 	git_config(git_fetch_config, NULL);
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
 
 	argc = parse_options(argc, argv, prefix,
 			     builtin_fetch_options, builtin_fetch_usage, 0);
@@ -2010,14 +2033,14 @@
 
 	if (deepen_relative) {
 		if (deepen_relative < 0)
-			die(_("Negative depth in --deepen is not supported"));
+			die(_("negative depth in --deepen is not supported"));
 		if (depth)
-			die(_("--deepen and --depth are mutually exclusive"));
+			die(_("options '%s' and '%s' cannot be used together"), "--deepen", "--depth");
 		depth = xstrfmt("%d", deepen_relative);
 	}
 	if (unshallow) {
 		if (depth)
-			die(_("--depth and --unshallow cannot be used together"));
+			die(_("options '%s' and '%s' cannot be used together"), "--depth", "--unshallow");
 		else if (!is_repository_shallow(the_repository))
 			die(_("--unshallow on a complete repository does not make sense"));
 		else
@@ -2047,14 +2070,15 @@
 		/* All arguments are assumed to be remotes or groups */
 		for (i = 0; i < argc; i++)
 			if (!add_remote_or_group(argv[i], &list))
-				die(_("No such remote or remote group: %s"), argv[i]);
+				die(_("no such remote or remote group: %s"),
+				    argv[i]);
 	} else {
 		/* Single remote or group */
 		(void) add_remote_or_group(argv[0], &list);
 		if (list.nr > 1) {
 			/* More than one remote */
 			if (argc > 1)
-				die(_("Fetching a group and specifying refspecs does not make sense"));
+				die(_("fetching a group and specifying refspecs does not make sense"));
 		} else {
 			/* Zero or one remotes */
 			remote = remote_get(argv[0]);
@@ -2075,7 +2099,7 @@
 		if (gtransport->smart_options) {
 			gtransport->smart_options->acked_commits = &acked_commits;
 		} else {
-			warning(_("Protocol does not support --negotiate-only, exiting."));
+			warning(_("protocol does not support --negotiate-only, exiting"));
 			return 1;
 		}
 		if (server_options.nr)
diff --git a/builtin/fmt-merge-msg.c b/builtin/fmt-merge-msg.c
index 48a8699..8d8fd39 100644
--- a/builtin/fmt-merge-msg.c
+++ b/builtin/fmt-merge-msg.c
@@ -12,6 +12,7 @@
 {
 	const char *inpath = NULL;
 	const char *message = NULL;
+	char *into_name = NULL;
 	int shortlog_len = -1;
 	struct option options[] = {
 		{ OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
@@ -23,6 +24,8 @@
 		  DEFAULT_MERGE_LOG_LEN },
 		OPT_STRING('m', "message", &message, N_("text"),
 			N_("use <text> as start of message")),
+		OPT_STRING(0, "into-name", &into_name, N_("name"),
+			   N_("use <name> instead of the real target branch")),
 		OPT_FILENAME('F', "file", &inpath, N_("file to read from")),
 		OPT_END()
 	};
@@ -56,6 +59,7 @@
 	opts.add_title = !message;
 	opts.credit_people = 1;
 	opts.shortlog_len = shortlog_len;
+	opts.into_name = into_name;
 
 	ret = fmt_merge_msg(&input, &output, &opts);
 	if (ret)
diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 16a2c7d..6f62f40 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -17,7 +17,8 @@
 int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 {
 	int i;
-	struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
+	struct ref_sorting *sorting;
+	struct string_list sorting_options = STRING_LIST_INIT_DUP;
 	int maxcount = 0, icase = 0;
 	struct ref_array array;
 	struct ref_filter filter;
@@ -39,7 +40,7 @@
 		OPT_INTEGER( 0 , "count", &maxcount, N_("show only <n> matched refs")),
 		OPT_STRING(  0 , "format", &format.format, N_("format"), N_("format to use for the output")),
 		OPT__COLOR(&format.use_color, N_("respect format colors")),
-		OPT_REF_SORT(sorting_tail),
+		OPT_REF_SORT(&sorting_options),
 		OPT_CALLBACK(0, "points-at", &filter.points_at,
 			     N_("object"), N_("print only refs which points at the given object"),
 			     parse_opt_object_name),
@@ -70,8 +71,7 @@
 	if (verify_ref_format(&format))
 		usage_with_options(for_each_ref_usage, opts);
 
-	if (!sorting)
-		sorting = ref_default_sorting();
+	sorting = ref_sorting_options(&sorting_options);
 	ref_sorting_set_sort_flags_all(sorting, REF_SORTING_ICASE, icase);
 	filter.ignore_case = icase;
 
diff --git a/builtin/fsck.c b/builtin/fsck.c
index 27b9e78..9e54892 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -944,15 +944,13 @@
 
 	if (the_repository->settings.core_commit_graph) {
 		struct child_process commit_graph_verify = CHILD_PROCESS_INIT;
-		const char *verify_argv[] = { "commit-graph", "verify", NULL, NULL, NULL };
 
 		prepare_alt_odb(the_repository);
 		for (odb = the_repository->objects->odb; odb; odb = odb->next) {
 			child_process_init(&commit_graph_verify);
-			commit_graph_verify.argv = verify_argv;
 			commit_graph_verify.git_cmd = 1;
-			verify_argv[2] = "--object-dir";
-			verify_argv[3] = odb->path;
+			strvec_pushl(&commit_graph_verify.args, "commit-graph",
+				     "verify", "--object-dir", odb->path, NULL);
 			if (run_command(&commit_graph_verify))
 				errors_found |= ERROR_COMMIT_GRAPH;
 		}
@@ -960,15 +958,13 @@
 
 	if (the_repository->settings.core_multi_pack_index) {
 		struct child_process midx_verify = CHILD_PROCESS_INIT;
-		const char *midx_argv[] = { "multi-pack-index", "verify", NULL, NULL, NULL };
 
 		prepare_alt_odb(the_repository);
 		for (odb = the_repository->objects->odb; odb; odb = odb->next) {
 			child_process_init(&midx_verify);
-			midx_verify.argv = midx_argv;
 			midx_verify.git_cmd = 1;
-			midx_argv[2] = "--object-dir";
-			midx_argv[3] = odb->path;
+			strvec_pushl(&midx_verify.args, "multi-pack-index",
+				     "verify", "--object-dir", odb->path, NULL);
 			if (run_command(&midx_verify))
 				errors_found |= ERROR_MULTI_PACK_INDEX;
 		}
diff --git a/builtin/gc.c b/builtin/gc.c
index bcef6a4..8e60ef1 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -470,7 +470,8 @@
 /*
  * Returns 0 if there was no previous error and gc can proceed, 1 if
  * gc should not proceed due to an error in the last run. Prints a
- * message and returns -1 if an error occurred while reading gc.log
+ * message and returns with a non-[01] status code if an error occurred
+ * while reading gc.log
  */
 static int report_last_gc_error(void)
 {
@@ -484,7 +485,7 @@
 		if (errno == ENOENT)
 			goto done;
 
-		ret = error_errno(_("cannot stat '%s'"), gc_log_path);
+		ret = die_message_errno(_("cannot stat '%s'"), gc_log_path);
 		goto done;
 	}
 
@@ -493,7 +494,7 @@
 
 	len = strbuf_read_file(&sb, gc_log_path, 0);
 	if (len < 0)
-		ret = error_errno(_("cannot read '%s'"), gc_log_path);
+		ret = die_message_errno(_("cannot read '%s'"), gc_log_path);
 	else if (len > 0) {
 		/*
 		 * A previous gc failed.  Report the error, and don't
@@ -611,12 +612,13 @@
 		}
 		if (detach_auto) {
 			int ret = report_last_gc_error();
-			if (ret < 0)
-				/* an I/O error occurred, already reported */
-				exit(128);
+
 			if (ret == 1)
 				/* Last gc --auto failed. Skip this one. */
 				return 0;
+			else if (ret)
+				/* an I/O error occurred, already reported */
+				return ret;
 
 			if (lock_repo_for_gc(force, &pid))
 				return 0;
diff --git a/builtin/help.c b/builtin/help.c
index 75cd2fb..d387131 100644
--- a/builtin/help.c
+++ b/builtin/help.c
@@ -212,11 +212,10 @@
 {
 	struct strbuf buffer = STRBUF_INIT;
 	struct child_process ec_process = CHILD_PROCESS_INIT;
-	const char *argv_ec[] = { "emacsclient", "--version", NULL };
 	int version;
 
 	/* emacsclient prints its version number on stderr */
-	ec_process.argv = argv_ec;
+	strvec_pushl(&ec_process.args, "emacsclient", "--version", NULL);
 	ec_process.err = -1;
 	ec_process.stdout_to_stderr = 1;
 	if (start_command(&ec_process))
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index c23d01d..3c2e6ae 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1845,11 +1845,11 @@
 	if (!pack_name && !from_stdin)
 		usage(index_pack_usage);
 	if (fix_thin_pack && !from_stdin)
-		die(_("--fix-thin cannot be used without --stdin"));
+		die(_("the option '%s' requires '%s'"), "--fix-thin", "--stdin");
 	if (from_stdin && !startup_info->have_repository)
 		die(_("--stdin requires a git repository"));
 	if (from_stdin && hash_algo)
-		die(_("--object-format cannot be used with --stdin"));
+		die(_("options '%s' and '%s' cannot be used together"), "--object-format", "--stdin");
 	if (!index_name && pack_name)
 		index_name = derive_filename(pack_name, "pack", "idx", &index_name_buf);
 
diff --git a/builtin/init-db.c b/builtin/init-db.c
index 2167796..546f9c5 100644
--- a/builtin/init-db.c
+++ b/builtin/init-db.c
@@ -557,7 +557,7 @@
 	argc = parse_options(argc, argv, prefix, init_db_options, init_db_usage, 0);
 
 	if (real_git_dir && is_bare_repository_cfg == 1)
-		die(_("--separate-git-dir and --bare are mutually exclusive"));
+		die(_("options '%s' and '%s' cannot be used together"), "--separate-git-dir", "--bare");
 
 	if (real_git_dir && !is_absolute_path(real_git_dir))
 		real_git_dir = real_pathdup(real_git_dir, 1);
diff --git a/builtin/log.c b/builtin/log.c
index f75d87e..4b49340 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -245,10 +245,24 @@
 			rev->abbrev_commit = 0;
 	}
 
-	if (rev->commit_format == CMIT_FMT_USERFORMAT && !w.decorate)
-		decoration_style = 0;
+	if (rev->commit_format == CMIT_FMT_USERFORMAT) {
+		if (!w.decorate) {
+			/*
+			 * Disable decoration loading if the format will not
+			 * show them anyway.
+			 */
+			decoration_style = 0;
+		} else if (!decoration_style) {
+			/*
+			 * If we are going to show them, make sure we do load
+			 * them here, but taking care not to override a
+			 * specific style set by config or --decorate.
+			 */
+			decoration_style = DECORATE_SHORT_REFS;
+		}
+	}
 
-	if (decoration_style) {
+	if (decoration_style || rev->simplify_by_decoration) {
 		const struct string_list *config_exclude =
 			repo_config_get_value_multi(the_repository,
 						    "log.excludeDecoration");
@@ -260,7 +274,8 @@
 						   item->string);
 		}
 
-		rev->show_decorations = 1;
+		if (decoration_style)
+			rev->show_decorations = 1;
 
 		load_ref_decorations(&decoration_filter, decoration_style);
 	}
@@ -1928,9 +1943,9 @@
 		numbered = 0;
 
 	if (numbered && keep_subject)
-		die(_("-n and -k are mutually exclusive"));
+		die(_("options '%s' and '%s' cannot be used together"), "-n", "-k");
 	if (keep_subject && subject_prefix)
-		die(_("--subject-prefix/--rfc and -k are mutually exclusive"));
+		die(_("options '%s' and '%s' cannot be used together"), "--subject-prefix/--rfc", "-k");
 	rev.preserve_subject = keep_subject;
 
 	argc = setup_revisions(argc, argv, &rev, &s_r_opt);
@@ -1964,7 +1979,7 @@
 		load_display_notes(&rev.notes_opt);
 
 	if (use_stdout + rev.diffopt.close_file + !!output_directory > 1)
-		die(_("--stdout, --output, and --output-directory are mutually exclusive"));
+		die(_("options '%s', '%s', and '%s' cannot be used together"), "--stdout", "--output", "--output-directory");
 
 	if (use_stdout) {
 		setup_pager();
@@ -2097,7 +2112,7 @@
 	if (creation_factor < 0)
 		creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT;
 	else if (!rdiff_prev)
-		die(_("--creation-factor requires --range-diff"));
+		die(_("the option '%s' requires '%s'"), "--creation-factor", "--range-diff");
 
 	if (rdiff_prev) {
 		if (!cover_letter && total != 1)
@@ -2241,6 +2256,7 @@
 	strbuf_release(&rdiff1);
 	strbuf_release(&rdiff2);
 	strbuf_release(&rdiff_title);
+	UNLEAK(rev);
 	return 0;
 }
 
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index 031fef1..f7ea56c 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -37,6 +37,7 @@
 static int show_eol;
 static int recurse_submodules;
 static int skipping_duplicates;
+static int show_sparse_dirs;
 
 static const char *prefix;
 static int max_prefix_len;
@@ -315,8 +316,10 @@
 
 	if (!(show_cached || show_stage || show_deleted || show_modified))
 		return;
-	/* TODO: audit for interaction with sparse-index. */
-	ensure_full_index(repo->index);
+
+	if (!show_sparse_dirs)
+		ensure_full_index(repo->index);
+
 	for (i = 0; i < repo->index->cache_nr; i++) {
 		const struct cache_entry *ce = repo->index->cache[i];
 		struct stat st;
@@ -670,6 +673,8 @@
 		OPT_BOOL(0, "debug", &debug_mode, N_("show debugging data")),
 		OPT_BOOL(0, "deduplicate", &skipping_duplicates,
 			 N_("suppress duplicate entries")),
+		OPT_BOOL(0, "sparse", &show_sparse_dirs,
+			 N_("show sparse directories in the presence of a sparse index")),
 		OPT_END()
 	};
 	int ret = 0;
@@ -677,6 +682,9 @@
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(ls_files_usage, builtin_ls_files_options);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	prefix = cmd_prefix;
 	if (prefix)
 		prefix_len = strlen(prefix);
@@ -767,7 +775,7 @@
 		 * would not make any sense with this option.
 		 */
 		if (show_stage || show_unmerged)
-			die("ls-files --with-tree is incompatible with -s or -u");
+			die(_("options '%s' and '%s' cannot be used together"), "ls-files --with-tree", "-s/-u");
 		overlay_tree_on_index(the_repository->index, with_tree, max_prefix);
 	}
 
diff --git a/builtin/ls-remote.c b/builtin/ls-remote.c
index 318949c..44448fa 100644
--- a/builtin/ls-remote.c
+++ b/builtin/ls-remote.c
@@ -54,7 +54,7 @@
 	struct transport *transport;
 	const struct ref *ref;
 	struct ref_array ref_array;
-	static struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
+	struct string_list sorting_options = STRING_LIST_INIT_DUP;
 
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("do not print remote URL")),
@@ -68,7 +68,7 @@
 		OPT_BIT(0, "refs", &flags, N_("do not show peeled tags"), REF_NORMAL),
 		OPT_BOOL(0, "get-url", &get_url,
 			 N_("take url.<base>.insteadOf into account")),
-		OPT_REF_SORT(sorting_tail),
+		OPT_REF_SORT(&sorting_options),
 		OPT_SET_INT_F(0, "exit-code", &status,
 			      N_("exit with exit code 2 if no matching refs are found"),
 			      2, PARSE_OPT_NOCOMPLETE),
@@ -86,8 +86,6 @@
 
 	packet_trace_identity("ls-remote");
 
-	UNLEAK(sorting);
-
 	if (argc > 1) {
 		int i;
 		CALLOC_ARRAY(pattern, argc);
@@ -139,8 +137,13 @@
 		item->symref = xstrdup_or_null(ref->symref);
 	}
 
-	if (sorting)
+	if (sorting_options.nr) {
+		struct ref_sorting *sorting;
+
+		sorting = ref_sorting_options(&sorting_options);
 		ref_array_sort(sorting, &ref_array);
+		ref_sorting_release(sorting);
+	}
 
 	for (i = 0; i < ref_array.nr; i++) {
 		const struct ref_array_item *ref = ref_array.items[i];
diff --git a/builtin/merge-file.c b/builtin/merge-file.c
index 06a2f90..e695867 100644
--- a/builtin/merge-file.c
+++ b/builtin/merge-file.c
@@ -34,6 +34,8 @@
 	struct option options[] = {
 		OPT_BOOL('p', "stdout", &to_stdout, N_("send results to standard output")),
 		OPT_SET_INT(0, "diff3", &xmp.style, N_("use a diff3 based merge"), XDL_MERGE_DIFF3),
+		OPT_SET_INT(0, "zdiff3", &xmp.style, N_("use a zealous diff3 based merge"),
+				XDL_MERGE_ZEALOUS_DIFF3),
 		OPT_SET_INT(0, "ours", &xmp.favor, N_("for conflicts, use our version"),
 			    XDL_MERGE_FAVOR_OURS),
 		OPT_SET_INT(0, "theirs", &xmp.favor, N_("for conflicts, use their version"),
diff --git a/builtin/merge.c b/builtin/merge.c
index ea3112e..74e53cf 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -87,6 +87,7 @@
 static const char *sign_commit;
 static int autostash;
 static int no_verify;
+static char *into_name;
 
 static struct strategy all_strategy[] = {
 	{ "recursive",  NO_TRIVIAL },
@@ -286,6 +287,8 @@
 	{ OPTION_LOWLEVEL_CALLBACK, 'F', "file", &merge_msg, N_("path"),
 		N_("read message from file"), PARSE_OPT_NONEG,
 		NULL, 0, option_read_message },
+	OPT_STRING(0, "into-name", &into_name, N_("name"),
+		   N_("use <name> instead of the real target")),
 	OPT__VERBOSITY(&verbosity),
 	OPT_BOOL(0, "abort", &abort_current_merge,
 		N_("abort the current in-progress merge")),
@@ -310,10 +313,9 @@
 	int len;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	struct strbuf buffer = STRBUF_INIT;
-	const char *argv[] = {"stash", "create", NULL};
 	int rc = -1;
 
-	cp.argv = argv;
+	strvec_pushl(&cp.args, "stash", "create", NULL);
 	cp.out = -1;
 	cp.git_cmd = 1;
 
@@ -1122,6 +1124,7 @@
 	opts.add_title = !have_message;
 	opts.shortlog_len = shortlog_len;
 	opts.credit_people = (0 < option_edit);
+	opts.into_name = into_name;
 
 	fmt_merge_msg(merge_names, merge_msg, &opts);
 	if (merge_msg->len)
@@ -1397,9 +1400,9 @@
 
 	if (squash) {
 		if (fast_forward == FF_NO)
-			die(_("You cannot combine --squash with --no-ff."));
+			die(_("options '%s' and '%s' cannot be used together"), "--squash", "--no-ff.");
 		if (option_commit > 0)
-			die(_("You cannot combine --squash with --commit."));
+			die(_("options '%s' and '%s' cannot be used together"), "--squash", "--commit.");
 		/*
 		 * squash can now silently disable option_commit - this is not
 		 * a problem as it is only overriding the default, not a user
diff --git a/builtin/multi-pack-index.c b/builtin/multi-pack-index.c
index 075d15d..4480ba3 100644
--- a/builtin/multi-pack-index.c
+++ b/builtin/multi-pack-index.c
@@ -167,6 +167,8 @@
 		usage_with_options(builtin_multi_pack_index_verify_usage,
 				   options);
 
+	FREE_AND_NULL(options);
+
 	return verify_midx_file(the_repository, opts.object_dir, opts.flags);
 }
 
@@ -191,6 +193,8 @@
 		usage_with_options(builtin_multi_pack_index_expire_usage,
 				   options);
 
+	FREE_AND_NULL(options);
+
 	return expire_midx_packs(the_repository, opts.object_dir, opts.flags);
 }
 
diff --git a/builtin/name-rev.c b/builtin/name-rev.c
index b221d30..27f6015 100644
--- a/builtin/name-rev.c
+++ b/builtin/name-rev.c
@@ -44,11 +44,20 @@
 	return is_valid_rev_name(name) ? name : NULL;
 }
 
+static int effective_distance(int distance, int generation)
+{
+	return distance + (generation > 0 ? MERGE_TRAVERSAL_WEIGHT : 0);
+}
+
 static int is_better_name(struct rev_name *name,
 			  timestamp_t taggerdate,
+			  int generation,
 			  int distance,
 			  int from_tag)
 {
+	int name_distance = effective_distance(name->distance, name->generation);
+	int new_distance = effective_distance(distance, generation);
+
 	/*
 	 * When comparing names based on tags, prefer names
 	 * based on the older tag, even if it is farther away.
@@ -56,7 +65,7 @@
 	if (from_tag && name->from_tag)
 		return (name->taggerdate > taggerdate ||
 			(name->taggerdate == taggerdate &&
-			 name->distance > distance));
+			 name_distance > new_distance));
 
 	/*
 	 * We know that at least one of them is a non-tag at this point.
@@ -69,8 +78,8 @@
 	 * We are now looking at two non-tags.  Tiebreak to favor
 	 * shorter hops.
 	 */
-	if (name->distance != distance)
-		return name->distance > distance;
+	if (name_distance != new_distance)
+		return name_distance > new_distance;
 
 	/* ... or tiebreak to favor older date */
 	if (name->taggerdate != taggerdate)
@@ -88,7 +97,7 @@
 	struct rev_name *name = commit_rev_name_at(&rev_names, commit);
 
 	if (is_valid_rev_name(name)) {
-		if (!is_better_name(name, taggerdate, distance, from_tag))
+		if (!is_better_name(name, taggerdate, generation, distance, from_tag))
 			return NULL;
 
 		/*
diff --git a/builtin/notes.c b/builtin/notes.c
index 71c5958..05d6048 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -134,14 +134,13 @@
 
 static void write_commented_object(int fd, const struct object_id *object)
 {
-	const char *show_args[5] =
-		{"show", "--stat", "--no-notes", oid_to_hex(object), NULL};
 	struct child_process show = CHILD_PROCESS_INIT;
 	struct strbuf buf = STRBUF_INIT;
 	struct strbuf cbuf = STRBUF_INIT;
 
 	/* Invoke "git show --stat --no-notes $object" */
-	show.argv = show_args;
+	strvec_pushl(&show.args, "show", "--stat", "--no-notes",
+		     oid_to_hex(object), NULL);
 	show.no_stdin = 1;
 	show.out = -1;
 	show.err = 0;
@@ -201,11 +200,12 @@
 static void write_note_data(struct note_data *d, struct object_id *oid)
 {
 	if (write_object_file(d->buf.buf, d->buf.len, blob_type, oid)) {
-		error(_("unable to write note object"));
+		int status = die_message(_("unable to write note object"));
+
 		if (d->edit_path)
-			error(_("the note contents have been left in %s"),
-				d->edit_path);
-		exit(128);
+			die_message(_("the note contents have been left in %s"),
+				    d->edit_path);
+		exit(status);
 	}
 }
 
@@ -861,15 +861,19 @@
 		update_ref(msg.buf, default_notes_ref(), &result_oid, NULL, 0,
 			   UPDATE_REFS_DIE_ON_ERR);
 	else { /* Merge has unresolved conflicts */
+		struct worktree **worktrees;
 		const struct worktree *wt;
 		/* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
 		update_ref(msg.buf, "NOTES_MERGE_PARTIAL", &result_oid, NULL,
 			   0, UPDATE_REFS_DIE_ON_ERR);
 		/* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
-		wt = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());
+		worktrees = get_worktrees();
+		wt = find_shared_symref(worktrees, "NOTES_MERGE_REF",
+					default_notes_ref());
 		if (wt)
 			die(_("a notes merge into %s is already in-progress at %s"),
 			    default_notes_ref(), wt->path);
+		free_worktrees(worktrees);
 		if (create_symref("NOTES_MERGE_REF", default_notes_ref(), NULL))
 			die(_("failed to store link to current notes ref (%s)"),
 			    default_notes_ref());
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 1a3dd44..ba2006f 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -3397,7 +3397,7 @@
 			if (feof(stdin))
 				break;
 			if (!ferror(stdin))
-				die("BUG: fgets returned NULL, not EOF, not error!");
+				BUG("fgets returned NULL, not EOF, not error!");
 			if (errno != EINTR)
 				die_errno("fgets");
 			clearerr(stdin);
@@ -4070,7 +4070,7 @@
 		die(_("--thin cannot be used to build an indexable pack"));
 
 	if (keep_unreachable && unpack_unreachable)
-		die(_("--keep-unreachable and --unpack-unreachable are incompatible"));
+		die(_("options '%s' and '%s' cannot be used together"), "--keep-unreachable", "--unpack-unreachable");
 	if (!rev_list_all || !rev_list_reflog || !rev_list_index)
 		unpack_unreachable_expiration = 0;
 
@@ -4148,11 +4148,10 @@
 		read_packs_list_from_stdin();
 		if (rev_list_unpacked)
 			add_unreachable_loose_objects();
-	} else if (!use_internal_rev_list)
+	} else if (!use_internal_rev_list) {
 		read_object_list_from_stdin();
-	else {
+	} else {
 		get_object_list(rp.nr, rp.v);
-		strvec_clear(&rp);
 	}
 	cleanup_preferred_base();
 	if (include_tag && nr_result)
@@ -4162,7 +4161,7 @@
 			    the_repository);
 
 	if (non_empty && !nr_result)
-		return 0;
+		goto cleanup;
 	if (nr_result) {
 		trace2_region_enter("pack-objects", "prepare-pack",
 				    the_repository);
@@ -4183,5 +4182,9 @@
 			     " pack-reused %"PRIu32),
 			   written, written_delta, reused, reused_delta,
 			   reuse_packfile_objects);
+
+cleanup:
+	strvec_clear(&rp);
+
 	return 0;
 }
diff --git a/builtin/prune.c b/builtin/prune.c
index 485c9a3..c2bcdc0 100644
--- a/builtin/prune.c
+++ b/builtin/prune.c
@@ -26,10 +26,22 @@
 		return error("Could not stat '%s'", fullpath);
 	if (st.st_mtime > expire)
 		return 0;
-	if (show_only || verbose)
-		printf("Removing stale temporary file %s\n", fullpath);
-	if (!show_only)
-		unlink_or_warn(fullpath);
+	if (S_ISDIR(st.st_mode)) {
+		if (show_only || verbose)
+			printf("Removing stale temporary directory %s\n", fullpath);
+		if (!show_only) {
+			struct strbuf remove_dir_buf = STRBUF_INIT;
+
+			strbuf_addstr(&remove_dir_buf, fullpath);
+			remove_dir_recursively(&remove_dir_buf, 0);
+			strbuf_release(&remove_dir_buf);
+		}
+	} else {
+		if (show_only || verbose)
+			printf("Removing stale temporary file %s\n", fullpath);
+		if (!show_only)
+			unlink_or_warn(fullpath);
+	}
 	return 0;
 }
 
diff --git a/builtin/pull.c b/builtin/pull.c
index 1cfaf9f..100cbf9 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -970,7 +970,7 @@
 		 "You can do so by running one of the following commands sometime before\n"
 		 "your next pull:\n"
 		 "\n"
-		 "  git config pull.rebase false  # merge (the default strategy)\n"
+		 "  git config pull.rebase false  # merge\n"
 		 "  git config pull.rebase true   # rebase\n"
 		 "  git config pull.ff only       # fast-forward only\n"
 		 "\n"
@@ -994,6 +994,8 @@
 		set_reflog_message(argc, argv);
 
 	git_config(git_pull_config, NULL);
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
 
 	argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 
diff --git a/builtin/push.c b/builtin/push.c
index 4b026ce..359db90 100644
--- a/builtin/push.c
+++ b/builtin/push.c
@@ -589,7 +589,7 @@
 	set_push_cert_flags(&flags, push_cert);
 
 	if (deleterefs && (tags || (flags & (TRANSPORT_PUSH_ALL | TRANSPORT_PUSH_MIRROR))))
-		die(_("--delete is incompatible with --all, --mirror and --tags"));
+		die(_("options '%s' and '%s' cannot be used together"), "--delete", "--all/--mirror/--tags");
 	if (deleterefs && argc < 2)
 		die(_("--delete doesn't make sense without any refs"));
 
@@ -627,18 +627,18 @@
 
 	if (flags & TRANSPORT_PUSH_ALL) {
 		if (tags)
-			die(_("--all and --tags are incompatible"));
+			die(_("options '%s' and '%s' cannot be used together"), "--all", "--tags");
 		if (argc >= 2)
 			die(_("--all can't be combined with refspecs"));
 	}
 	if (flags & TRANSPORT_PUSH_MIRROR) {
 		if (tags)
-			die(_("--mirror and --tags are incompatible"));
+			die(_("options '%s' and '%s' cannot be used together"), "--mirror", "--tags");
 		if (argc >= 2)
 			die(_("--mirror can't be combined with refspecs"));
 	}
 	if ((flags & TRANSPORT_PUSH_ALL) && (flags & TRANSPORT_PUSH_MIRROR))
-		die(_("--all and --mirror are incompatible"));
+		die(_("options '%s' and '%s' cannot be used together"), "--all", "--mirror");
 
 	if (!is_empty_cas(&cas) && (flags & TRANSPORT_PUSH_FORCE_IF_INCLUDES))
 		cas.use_force_if_includes = 1;
diff --git a/builtin/rebase.c b/builtin/rebase.c
index 34b4744..36490d0 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -1190,13 +1190,13 @@
 
 	if (keep_base) {
 		if (options.onto_name)
-			die(_("cannot combine '--keep-base' with '--onto'"));
+			die(_("options '%s' and '%s' cannot be used together"), "--keep-base", "--onto");
 		if (options.root)
-			die(_("cannot combine '--keep-base' with '--root'"));
+			die(_("options '%s' and '%s' cannot be used together"), "--keep-base", "--root");
 	}
 
 	if (options.root && options.fork_point > 0)
-		die(_("cannot combine '--root' with '--fork-point'"));
+		die(_("options '%s' and '%s' cannot be used together"), "--root", "--fork-point");
 
 	if (action != ACTION_NONE && !in_progress)
 		die(_("No rebase in progress?"));
@@ -1460,8 +1460,8 @@
 
 		if (i >= 0) {
 			if (is_merge(&options))
-				die(_("cannot combine apply options with "
-				      "merge options"));
+				die(_("apply options and merge options "
+					  "cannot be used together"));
 			else
 				options.type = REBASE_APPLY;
 		}
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 49b846d..9f4a0b8 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -175,7 +175,7 @@
 			strbuf_addf(&fsck_msg_types, "%c%s=%s",
 				fsck_msg_types.len ? ',' : '=', var, value);
 		else
-			warning("Skipping unknown msg id '%s'", var);
+			warning("skipping unknown msg id '%s'", var);
 		return 0;
 	}
 
@@ -769,8 +769,10 @@
 		memset(&sigcheck, '\0', sizeof(sigcheck));
 
 		bogs = parse_signed_buffer(push_cert.buf, push_cert.len);
-		check_signature(push_cert.buf, bogs, push_cert.buf + bogs,
-				push_cert.len - bogs, &sigcheck);
+		sigcheck.payload = xmemdupz(push_cert.buf, bogs);
+		sigcheck.payload_len = bogs;
+		check_signature(&sigcheck, push_cert.buf + bogs,
+				push_cert.len - bogs);
 
 		nonce_status = check_nonce(push_cert.buf, bogs);
 	}
@@ -812,16 +814,13 @@
 {
 	struct child_process proc = CHILD_PROCESS_INIT;
 	struct async muxer;
-	const char *argv[2];
 	int code;
+	const char *hook_path = find_hook(hook_name);
 
-	argv[0] = find_hook(hook_name);
-	if (!argv[0])
+	if (!hook_path)
 		return 0;
 
-	argv[1] = NULL;
-
-	proc.argv = argv;
+	strvec_push(&proc.args, hook_path);
 	proc.in = -1;
 	proc.stdout_to_stderr = 1;
 	proc.trace2_hook_name = hook_name;
@@ -943,23 +942,21 @@
 
 static int run_update_hook(struct command *cmd)
 {
-	const char *argv[5];
 	struct child_process proc = CHILD_PROCESS_INIT;
 	int code;
+	const char *hook_path = find_hook("update");
 
-	argv[0] = find_hook("update");
-	if (!argv[0])
+	if (!hook_path)
 		return 0;
 
-	argv[1] = cmd->ref_name;
-	argv[2] = oid_to_hex(&cmd->old_oid);
-	argv[3] = oid_to_hex(&cmd->new_oid);
-	argv[4] = NULL;
+	strvec_push(&proc.args, hook_path);
+	strvec_push(&proc.args, cmd->ref_name);
+	strvec_push(&proc.args, oid_to_hex(&cmd->old_oid));
+	strvec_push(&proc.args, oid_to_hex(&cmd->new_oid));
 
 	proc.no_stdin = 1;
 	proc.stdout_to_stderr = 1;
 	proc.err = use_sideband ? -1 : 0;
-	proc.argv = argv;
 	proc.trace2_hook_name = "update";
 
 	code = start_command(&proc);
@@ -1117,22 +1114,20 @@
 	struct child_process proc = CHILD_PROCESS_INIT;
 	struct async muxer;
 	struct command *cmd;
-	const char *argv[2];
 	struct packet_reader reader;
 	struct strbuf cap = STRBUF_INIT;
 	struct strbuf errmsg = STRBUF_INIT;
 	int hook_use_push_options = 0;
 	int version = 0;
 	int code;
+	const char *hook_path = find_hook("proc-receive");
 
-	argv[0] = find_hook("proc-receive");
-	if (!argv[0]) {
+	if (!hook_path) {
 		rp_error("cannot find hook 'proc-receive'");
 		return -1;
 	}
-	argv[1] = NULL;
 
-	proc.argv = argv;
+	strvec_push(&proc.args, hook_path);
 	proc.in = -1;
 	proc.out = -1;
 	proc.trace2_hook_name = "proc-receive";
@@ -1370,23 +1365,11 @@
 				  struct strvec *env,
 				  const char *work_tree)
 {
-	const char *update_refresh[] = {
-		"update-index", "-q", "--ignore-submodules", "--refresh", NULL
-	};
-	const char *diff_files[] = {
-		"diff-files", "--quiet", "--ignore-submodules", "--", NULL
-	};
-	const char *diff_index[] = {
-		"diff-index", "--quiet", "--cached", "--ignore-submodules",
-		NULL, "--", NULL
-	};
-	const char *read_tree[] = {
-		"read-tree", "-u", "-m", NULL, NULL
-	};
 	struct child_process child = CHILD_PROCESS_INIT;
 
-	child.argv = update_refresh;
-	child.env = env->v;
+	strvec_pushl(&child.args, "update-index", "-q", "--ignore-submodules",
+		     "--refresh", NULL);
+	strvec_pushv(&child.env_array, env->v);
 	child.dir = work_tree;
 	child.no_stdin = 1;
 	child.stdout_to_stderr = 1;
@@ -1396,8 +1379,9 @@
 
 	/* run_command() does not clean up completely; reinitialize */
 	child_process_init(&child);
-	child.argv = diff_files;
-	child.env = env->v;
+	strvec_pushl(&child.args, "diff-files", "--quiet",
+		     "--ignore-submodules", "--", NULL);
+	strvec_pushv(&child.env_array, env->v);
 	child.dir = work_tree;
 	child.no_stdin = 1;
 	child.stdout_to_stderr = 1;
@@ -1405,12 +1389,13 @@
 	if (run_command(&child))
 		return "Working directory has unstaged changes";
 
-	/* diff-index with either HEAD or an empty tree */
-	diff_index[4] = head_has_history() ? "HEAD" : empty_tree_oid_hex();
-
 	child_process_init(&child);
-	child.argv = diff_index;
-	child.env = env->v;
+	strvec_pushl(&child.args, "diff-index", "--quiet", "--cached",
+		     "--ignore-submodules",
+		     /* diff-index with either HEAD or an empty tree */
+		     head_has_history() ? "HEAD" : empty_tree_oid_hex(),
+		     "--", NULL);
+	strvec_pushv(&child.env_array, env->v);
 	child.no_stdin = 1;
 	child.no_stdout = 1;
 	child.stdout_to_stderr = 0;
@@ -1418,10 +1403,10 @@
 	if (run_command(&child))
 		return "Working directory has staged changes";
 
-	read_tree[3] = hash_to_hex(sha1);
 	child_process_init(&child);
-	child.argv = read_tree;
-	child.env = env->v;
+	strvec_pushl(&child.args, "read-tree", "-u", "-m", hash_to_hex(sha1),
+		     NULL);
+	strvec_pushv(&child.env_array, env->v);
 	child.dir = work_tree;
 	child.no_stdin = 1;
 	child.no_stdout = 1;
@@ -1449,29 +1434,22 @@
 
 static const char *update_worktree(unsigned char *sha1, const struct worktree *worktree)
 {
-	const char *retval, *work_tree, *git_dir = NULL;
+	const char *retval, *git_dir;
 	struct strvec env = STRVEC_INIT;
 
-	if (worktree && worktree->path)
-		work_tree = worktree->path;
-	else if (git_work_tree_cfg)
-		work_tree = git_work_tree_cfg;
-	else
-		work_tree = "..";
+	if (!worktree || !worktree->path)
+		BUG("worktree->path must be non-NULL");
 
-	if (is_bare_repository())
+	if (worktree->is_bare)
 		return "denyCurrentBranch = updateInstead needs a worktree";
-	if (worktree)
-		git_dir = get_worktree_git_dir(worktree);
-	if (!git_dir)
-		git_dir = get_git_dir();
+	git_dir = get_worktree_git_dir(worktree);
 
 	strvec_pushf(&env, "GIT_DIR=%s", absolute_path(git_dir));
 
 	if (!hook_exists(push_to_checkout_hook))
-		retval = push_to_deploy(sha1, &env, work_tree);
+		retval = push_to_deploy(sha1, &env, worktree->path);
 	else
-		retval = push_to_checkout(sha1, &env, work_tree);
+		retval = push_to_checkout(sha1, &env, worktree->path);
 
 	strvec_clear(&env);
 	return retval;
@@ -1486,19 +1464,22 @@
 	struct object_id *old_oid = &cmd->old_oid;
 	struct object_id *new_oid = &cmd->new_oid;
 	int do_update_worktree = 0;
-	const struct worktree *worktree = is_bare_repository() ? NULL : find_shared_symref("HEAD", name);
+	struct worktree **worktrees = get_worktrees();
+	const struct worktree *worktree =
+		find_shared_symref(worktrees, "HEAD", name);
 
 	/* only refs/... are allowed */
 	if (!starts_with(name, "refs/") || check_refname_format(name + 5, 0)) {
 		rp_error("refusing to create funny ref '%s' remotely", name);
-		return "funny refname";
+		ret = "funny refname";
+		goto out;
 	}
 
 	strbuf_addf(&namespaced_name_buf, "%s%s", get_git_namespace(), name);
 	free(namespaced_name);
 	namespaced_name = strbuf_detach(&namespaced_name_buf, NULL);
 
-	if (worktree) {
+	if (worktree && !worktree->is_bare) {
 		switch (deny_current_branch) {
 		case DENY_IGNORE:
 			break;
@@ -1510,7 +1491,8 @@
 			rp_error("refusing to update checked out branch: %s", name);
 			if (deny_current_branch == DENY_UNCONFIGURED)
 				refuse_unconfigured_deny();
-			return "branch is currently checked out";
+			ret = "branch is currently checked out";
+			goto out;
 		case DENY_UPDATE_INSTEAD:
 			/* pass -- let other checks intervene first */
 			do_update_worktree = 1;
@@ -1521,13 +1503,15 @@
 	if (!is_null_oid(new_oid) && !has_object_file(new_oid)) {
 		error("unpack should have generated %s, "
 		      "but I can't find it!", oid_to_hex(new_oid));
-		return "bad pack";
+		ret = "bad pack";
+		goto out;
 	}
 
 	if (!is_null_oid(old_oid) && is_null_oid(new_oid)) {
 		if (deny_deletes && starts_with(name, "refs/heads/")) {
 			rp_error("denying ref deletion for %s", name);
-			return "deletion prohibited";
+			ret = "deletion prohibited";
+			goto out;
 		}
 
 		if (worktree || (head_name && !strcmp(namespaced_name, head_name))) {
@@ -1543,9 +1527,11 @@
 				if (deny_delete_current == DENY_UNCONFIGURED)
 					refuse_unconfigured_deny_delete_current();
 				rp_error("refusing to delete the current branch: %s", name);
-				return "deletion of the current branch prohibited";
+				ret = "deletion of the current branch prohibited";
+				goto out;
 			default:
-				return "Invalid denyDeleteCurrent setting";
+				ret = "Invalid denyDeleteCurrent setting";
+				goto out;
 			}
 		}
 	}
@@ -1563,25 +1549,28 @@
 		    old_object->type != OBJ_COMMIT ||
 		    new_object->type != OBJ_COMMIT) {
 			error("bad sha1 objects for %s", name);
-			return "bad ref";
+			ret = "bad ref";
+			goto out;
 		}
 		old_commit = (struct commit *)old_object;
 		new_commit = (struct commit *)new_object;
 		if (!in_merge_bases(old_commit, new_commit)) {
 			rp_error("denying non-fast-forward %s"
 				 " (you should pull first)", name);
-			return "non-fast-forward";
+			ret = "non-fast-forward";
+			goto out;
 		}
 	}
 	if (run_update_hook(cmd)) {
 		rp_error("hook declined to update %s", name);
-		return "hook declined";
+		ret = "hook declined";
+		goto out;
 	}
 
 	if (do_update_worktree) {
-		ret = update_worktree(new_oid->hash, find_shared_symref("HEAD", name));
+		ret = update_worktree(new_oid->hash, worktree);
 		if (ret)
-			return ret;
+			goto out;
 	}
 
 	if (is_null_oid(new_oid)) {
@@ -1589,9 +1578,9 @@
 		if (!parse_object(the_repository, old_oid)) {
 			old_oid = NULL;
 			if (ref_exists(name)) {
-				rp_warning("Allowing deletion of corrupt ref.");
+				rp_warning("allowing deletion of corrupt ref");
 			} else {
-				rp_warning("Deleting a non-existent ref.");
+				rp_warning("deleting a non-existent ref");
 				cmd->did_not_exist = 1;
 			}
 		}
@@ -1600,17 +1589,19 @@
 					   old_oid,
 					   0, "push", &err)) {
 			rp_error("%s", err.buf);
-			strbuf_release(&err);
-			return "failed to delete";
+			ret = "failed to delete";
+		} else {
+			ret = NULL; /* good */
 		}
 		strbuf_release(&err);
-		return NULL; /* good */
 	}
 	else {
 		struct strbuf err = STRBUF_INIT;
 		if (shallow_update && si->shallow_ref[cmd->index] &&
-		    update_shallow_ref(cmd, si))
-			return "shallow error";
+		    update_shallow_ref(cmd, si)) {
+			ret = "shallow error";
+			goto out;
+		}
 
 		if (ref_transaction_update(transaction,
 					   namespaced_name,
@@ -1618,14 +1609,16 @@
 					   0, "push",
 					   &err)) {
 			rp_error("%s", err.buf);
-			strbuf_release(&err);
-
-			return "failed to update ref";
+			ret = "failed to update ref";
+		} else {
+			ret = NULL; /* good */
 		}
 		strbuf_release(&err);
-
-		return NULL; /* good */
 	}
+
+out:
+	free_worktrees(worktrees);
+	return ret;
 }
 
 static void run_update_post_hook(struct command *commands)
@@ -2213,13 +2206,14 @@
 		strvec_push(&child.args, alt_shallow_file);
 	}
 
-	tmp_objdir = tmp_objdir_create();
+	tmp_objdir = tmp_objdir_create("incoming");
 	if (!tmp_objdir) {
 		if (err_fd > 0)
 			close(err_fd);
 		return "unable to create temporary object directory";
 	}
-	child.env = tmp_objdir_env(tmp_objdir);
+	if (tmp_objdir)
+		strvec_pushv(&child.env_array, tmp_objdir_env(tmp_objdir));
 
 	/*
 	 * Normally we just pass the tmp_objdir environment to the child
@@ -2490,9 +2484,9 @@
 	argc = parse_options(argc, argv, prefix, options, receive_pack_usage, 0);
 
 	if (argc > 1)
-		usage_msg_opt(_("Too many arguments."), receive_pack_usage, options);
+		usage_msg_opt(_("too many arguments"), receive_pack_usage, options);
 	if (argc == 0)
-		usage_msg_opt(_("You must specify a directory."), receive_pack_usage, options);
+		usage_msg_opt(_("you must specify a directory"), receive_pack_usage, options);
 
 	service_dir = argv[0];
 
@@ -2566,25 +2560,25 @@
 				 &push_options);
 		if (pack_lockfile)
 			unlink_or_warn(pack_lockfile);
+		sigchain_push(SIGPIPE, SIG_IGN);
 		if (report_status_v2)
 			report_v2(commands, unpack_status);
 		else if (report_status)
 			report(commands, unpack_status);
+		sigchain_pop(SIGPIPE);
 		run_receive_hook(commands, "post-receive", 1,
 				 &push_options);
 		run_update_post_hook(commands);
 		string_list_clear(&push_options, 0);
 		if (auto_gc) {
-			const char *argv_gc_auto[] = {
-				"gc", "--auto", "--quiet", NULL,
-			};
 			struct child_process proc = CHILD_PROCESS_INIT;
 
 			proc.no_stdin = 1;
 			proc.stdout_to_stderr = 1;
 			proc.err = use_sideband ? -1 : 0;
 			proc.git_cmd = proc.close_object_store = 1;
-			proc.argv = argv_gc_auto;
+			strvec_pushl(&proc.args, "gc", "--auto", "--quiet",
+				     NULL);
 
 			if (!start_command(&proc)) {
 				if (use_sideband)
diff --git a/builtin/reflog.c b/builtin/reflog.c
index 175c83e..a4b1dd2 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -28,7 +28,6 @@
 static timestamp_t default_reflog_expire_unreachable;
 
 struct cmd_reflog_expire_cb {
-	struct rev_info revs;
 	int stalefix;
 	timestamp_t expire_total;
 	timestamp_t expire_unreachable;
@@ -46,18 +45,12 @@
 	struct cmd_reflog_expire_cb cmd;
 	struct commit *tip_commit;
 	struct commit_list *tips;
+	unsigned int dry_run:1;
 };
 
-struct collected_reflog {
-	struct object_id oid;
-	char reflog[FLEX_ARRAY];
-};
-
-struct collect_reflog_cb {
-	struct collected_reflog **e;
-	int alloc;
-	int nr;
-	struct worktree *wt;
+struct worktree_reflogs {
+	struct worktree *worktree;
+	struct string_list reflogs;
 };
 
 /* Remember to update object flag allocation in object.h */
@@ -310,10 +303,15 @@
 		return 1;
 
 	if (timestamp < cb->cmd.expire_unreachable) {
-		if (cb->unreachable_expire_kind == UE_ALWAYS)
+		switch (cb->unreachable_expire_kind) {
+		case UE_ALWAYS:
 			return 1;
-		if (unreachable(cb, old_commit, ooid) || unreachable(cb, new_commit, noid))
-			return 1;
+		case UE_NORMAL:
+		case UE_HEAD:
+			if (unreachable(cb, old_commit, ooid) || unreachable(cb, new_commit, noid))
+				return 1;
+			break;
+		}
 	}
 
 	if (cb->cmd.recno && --(cb->cmd.recno) == 0)
@@ -322,6 +320,28 @@
 	return 0;
 }
 
+static int should_expire_reflog_ent_verbose(struct object_id *ooid,
+					    struct object_id *noid,
+					    const char *email,
+					    timestamp_t timestamp, int tz,
+					    const char *message, void *cb_data)
+{
+	struct expire_reflog_policy_cb *cb = cb_data;
+	int expire;
+
+	expire = should_expire_reflog_ent(ooid, noid, email, timestamp, tz,
+					  message, cb);
+
+	if (!expire)
+		printf("keep %s", message);
+	else if (cb->dry_run)
+		printf("would prune %s", message);
+	else
+		printf("prune %s", message);
+
+	return expire;
+}
+
 static int push_tip_to_list(const char *refname, const struct object_id *oid,
 			    int flags, void *cb_data)
 {
@@ -355,75 +375,71 @@
 				  void *cb_data)
 {
 	struct expire_reflog_policy_cb *cb = cb_data;
+	struct commit_list *elem;
+	struct commit *commit = NULL;
 
 	if (!cb->cmd.expire_unreachable || is_head(refname)) {
-		cb->tip_commit = NULL;
 		cb->unreachable_expire_kind = UE_HEAD;
 	} else {
-		cb->tip_commit = lookup_commit_reference_gently(the_repository,
-								oid, 1);
-		if (!cb->tip_commit)
-			cb->unreachable_expire_kind = UE_ALWAYS;
-		else
-			cb->unreachable_expire_kind = UE_NORMAL;
+		commit = lookup_commit(the_repository, oid);
+		cb->unreachable_expire_kind = commit ? UE_NORMAL : UE_ALWAYS;
 	}
 
 	if (cb->cmd.expire_unreachable <= cb->cmd.expire_total)
 		cb->unreachable_expire_kind = UE_ALWAYS;
 
-	cb->mark_list = NULL;
-	cb->tips = NULL;
-	if (cb->unreachable_expire_kind != UE_ALWAYS) {
-		if (cb->unreachable_expire_kind == UE_HEAD) {
-			struct commit_list *elem;
-
-			for_each_ref(push_tip_to_list, &cb->tips);
-			for (elem = cb->tips; elem; elem = elem->next)
-				commit_list_insert(elem->item, &cb->mark_list);
-		} else {
-			commit_list_insert(cb->tip_commit, &cb->mark_list);
-		}
-		cb->mark_limit = cb->cmd.expire_total;
-		mark_reachable(cb);
+	switch (cb->unreachable_expire_kind) {
+	case UE_ALWAYS:
+		return;
+	case UE_HEAD:
+		for_each_ref(push_tip_to_list, &cb->tips);
+		for (elem = cb->tips; elem; elem = elem->next)
+			commit_list_insert(elem->item, &cb->mark_list);
+		break;
+	case UE_NORMAL:
+		commit_list_insert(commit, &cb->mark_list);
+		/* For reflog_expiry_cleanup() below */
+		cb->tip_commit = commit;
 	}
+	cb->mark_limit = cb->cmd.expire_total;
+	mark_reachable(cb);
 }
 
 static void reflog_expiry_cleanup(void *cb_data)
 {
 	struct expire_reflog_policy_cb *cb = cb_data;
+	struct commit_list *elem;
 
-	if (cb->unreachable_expire_kind != UE_ALWAYS) {
-		if (cb->unreachable_expire_kind == UE_HEAD) {
-			struct commit_list *elem;
-			for (elem = cb->tips; elem; elem = elem->next)
-				clear_commit_marks(elem->item, REACHABLE);
-			free_commit_list(cb->tips);
-		} else {
-			clear_commit_marks(cb->tip_commit, REACHABLE);
-		}
+	switch (cb->unreachable_expire_kind) {
+	case UE_ALWAYS:
+		return;
+	case UE_HEAD:
+		for (elem = cb->tips; elem; elem = elem->next)
+			clear_commit_marks(elem->item, REACHABLE);
+		free_commit_list(cb->tips);
+		break;
+	case UE_NORMAL:
+		clear_commit_marks(cb->tip_commit, REACHABLE);
+		break;
 	}
 }
 
 static int collect_reflog(const char *ref, const struct object_id *oid, int unused, void *cb_data)
 {
-	struct collected_reflog *e;
-	struct collect_reflog_cb *cb = cb_data;
+	struct worktree_reflogs *cb = cb_data;
+	struct worktree *worktree = cb->worktree;
 	struct strbuf newref = STRBUF_INIT;
 
 	/*
 	 * Avoid collecting the same shared ref multiple times because
 	 * they are available via all worktrees.
 	 */
-	if (!cb->wt->is_current && ref_type(ref) == REF_TYPE_NORMAL)
+	if (!worktree->is_current && ref_type(ref) == REF_TYPE_NORMAL)
 		return 0;
 
-	strbuf_worktree_ref(cb->wt, &newref, ref);
-	FLEX_ALLOC_STR(e, reflog, newref.buf);
-	strbuf_release(&newref);
+	strbuf_worktree_ref(worktree, &newref, ref);
+	string_list_append_nodup(&cb->reflogs, strbuf_detach(&newref, NULL));
 
-	oidcpy(&e->oid, oid);
-	ALLOC_GROW(cb->e, cb->nr + 1, cb->alloc);
-	cb->e[cb->nr++] = e;
 	return 0;
 }
 
@@ -541,11 +557,13 @@
 
 static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 {
-	struct expire_reflog_policy_cb cb;
+	struct cmd_reflog_expire_cb cmd = { 0 };
 	timestamp_t now = time(NULL);
 	int i, status, do_all, all_worktrees = 1;
 	int explicit_expiry = 0;
 	unsigned int flags = 0;
+	int verbose = 0;
+	reflog_expiry_should_prune_fn *should_prune_fn = should_expire_reflog_ent;
 
 	default_reflog_expire_unreachable = now - 30 * 24 * 3600;
 	default_reflog_expire = now - 90 * 24 * 3600;
@@ -553,10 +571,9 @@
 
 	save_commit_buffer = 0;
 	do_all = status = 0;
-	memset(&cb, 0, sizeof(cb));
 
-	cb.cmd.expire_total = default_reflog_expire;
-	cb.cmd.expire_unreachable = default_reflog_expire_unreachable;
+	cmd.expire_total = default_reflog_expire;
+	cmd.expire_unreachable = default_reflog_expire_unreachable;
 
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
@@ -564,17 +581,17 @@
 		if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n"))
 			flags |= EXPIRE_REFLOGS_DRY_RUN;
 		else if (skip_prefix(arg, "--expire=", &arg)) {
-			if (parse_expiry_date(arg, &cb.cmd.expire_total))
+			if (parse_expiry_date(arg, &cmd.expire_total))
 				die(_("'%s' is not a valid timestamp"), arg);
 			explicit_expiry |= EXPIRE_TOTAL;
 		}
 		else if (skip_prefix(arg, "--expire-unreachable=", &arg)) {
-			if (parse_expiry_date(arg, &cb.cmd.expire_unreachable))
+			if (parse_expiry_date(arg, &cmd.expire_unreachable))
 				die(_("'%s' is not a valid timestamp"), arg);
 			explicit_expiry |= EXPIRE_UNREACH;
 		}
 		else if (!strcmp(arg, "--stale-fix"))
-			cb.cmd.stalefix = 1;
+			cmd.stalefix = 1;
 		else if (!strcmp(arg, "--rewrite"))
 			flags |= EXPIRE_REFLOGS_REWRITE;
 		else if (!strcmp(arg, "--updateref"))
@@ -584,7 +601,7 @@
 		else if (!strcmp(arg, "--single-worktree"))
 			all_worktrees = 0;
 		else if (!strcmp(arg, "--verbose"))
-			flags |= EXPIRE_REFLOGS_VERBOSE;
+			verbose = 1;
 		else if (!strcmp(arg, "--")) {
 			i++;
 			break;
@@ -595,54 +612,65 @@
 			break;
 	}
 
+	if (verbose)
+		should_prune_fn = should_expire_reflog_ent_verbose;
+
 	/*
 	 * We can trust the commits and objects reachable from refs
 	 * even in older repository.  We cannot trust what's reachable
 	 * from reflog if the repository was pruned with older git.
 	 */
-	if (cb.cmd.stalefix) {
-		repo_init_revisions(the_repository, &cb.cmd.revs, prefix);
-		cb.cmd.revs.do_not_die_on_missing_tree = 1;
-		cb.cmd.revs.ignore_missing = 1;
-		cb.cmd.revs.ignore_missing_links = 1;
-		if (flags & EXPIRE_REFLOGS_VERBOSE)
+	if (cmd.stalefix) {
+		struct rev_info revs;
+
+		repo_init_revisions(the_repository, &revs, prefix);
+		revs.do_not_die_on_missing_tree = 1;
+		revs.ignore_missing = 1;
+		revs.ignore_missing_links = 1;
+		if (verbose)
 			printf(_("Marking reachable objects..."));
-		mark_reachable_objects(&cb.cmd.revs, 0, 0, NULL);
-		if (flags & EXPIRE_REFLOGS_VERBOSE)
+		mark_reachable_objects(&revs, 0, 0, NULL);
+		if (verbose)
 			putchar('\n');
 	}
 
 	if (do_all) {
-		struct collect_reflog_cb collected;
+		struct worktree_reflogs collected = {
+			.reflogs = STRING_LIST_INIT_DUP,
+		};
+		struct string_list_item *item;
 		struct worktree **worktrees, **p;
-		int i;
 
-		memset(&collected, 0, sizeof(collected));
 		worktrees = get_worktrees();
 		for (p = worktrees; *p; p++) {
 			if (!all_worktrees && !(*p)->is_current)
 				continue;
-			collected.wt = *p;
+			collected.worktree = *p;
 			refs_for_each_reflog(get_worktree_ref_store(*p),
 					     collect_reflog, &collected);
 		}
 		free_worktrees(worktrees);
-		for (i = 0; i < collected.nr; i++) {
-			struct collected_reflog *e = collected.e[i];
 
-			set_reflog_expiry_param(&cb.cmd, explicit_expiry, e->reflog);
-			status |= reflog_expire(e->reflog, flags,
+		for_each_string_list_item(item, &collected.reflogs) {
+			struct expire_reflog_policy_cb cb = {
+				.cmd = cmd,
+				.dry_run = !!(flags & EXPIRE_REFLOGS_DRY_RUN),
+			};
+
+			set_reflog_expiry_param(&cb.cmd, explicit_expiry, item->string);
+			status |= reflog_expire(item->string, flags,
 						reflog_expiry_prepare,
-						should_expire_reflog_ent,
+						should_prune_fn,
 						reflog_expiry_cleanup,
 						&cb);
-			free(e);
 		}
-		free(collected.e);
+		string_list_clear(&collected.reflogs, 0);
 	}
 
 	for (; i < argc; i++) {
 		char *ref;
+		struct expire_reflog_policy_cb cb = { .cmd = cmd };
+
 		if (!dwim_log(argv[i], strlen(argv[i]), NULL, &ref)) {
 			status |= error(_("%s points nowhere!"), argv[i]);
 			continue;
@@ -650,7 +678,7 @@
 		set_reflog_expiry_param(&cb.cmd, explicit_expiry, ref);
 		status |= reflog_expire(ref, flags,
 					reflog_expiry_prepare,
-					should_expire_reflog_ent,
+					should_prune_fn,
 					reflog_expiry_cleanup,
 					&cb);
 		free(ref);
@@ -662,19 +690,19 @@
 		const char *email, timestamp_t timestamp, int tz,
 		const char *message, void *cb_data)
 {
-	struct expire_reflog_policy_cb *cb = cb_data;
-	if (!cb->cmd.expire_total || timestamp < cb->cmd.expire_total)
-		cb->cmd.recno++;
+	struct cmd_reflog_expire_cb *cb = cb_data;
+	if (!cb->expire_total || timestamp < cb->expire_total)
+		cb->recno++;
 	return 0;
 }
 
 static int cmd_reflog_delete(int argc, const char **argv, const char *prefix)
 {
-	struct expire_reflog_policy_cb cb;
+	struct cmd_reflog_expire_cb cmd = { 0 };
 	int i, status = 0;
 	unsigned int flags = 0;
-
-	memset(&cb, 0, sizeof(cb));
+	int verbose = 0;
+	reflog_expiry_should_prune_fn *should_prune_fn = should_expire_reflog_ent;
 
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
@@ -685,7 +713,7 @@
 		else if (!strcmp(arg, "--updateref"))
 			flags |= EXPIRE_REFLOGS_UPDATE_REF;
 		else if (!strcmp(arg, "--verbose"))
-			flags |= EXPIRE_REFLOGS_VERBOSE;
+			verbose = 1;
 		else if (!strcmp(arg, "--")) {
 			i++;
 			break;
@@ -696,6 +724,9 @@
 			break;
 	}
 
+	if (verbose)
+		should_prune_fn = should_expire_reflog_ent_verbose;
+
 	if (argc - i < 1)
 		return error(_("no reflog specified to delete"));
 
@@ -703,6 +734,9 @@
 		const char *spec = strstr(argv[i], "@{");
 		char *ep, *ref;
 		int recno;
+		struct expire_reflog_policy_cb cb = {
+			.dry_run = !!(flags & EXPIRE_REFLOGS_DRY_RUN),
+		};
 
 		if (!spec) {
 			status |= error(_("not a reflog: %s"), argv[i]);
@@ -716,17 +750,18 @@
 
 		recno = strtoul(spec + 2, &ep, 10);
 		if (*ep == '}') {
-			cb.cmd.recno = -recno;
-			for_each_reflog_ent(ref, count_reflog_ent, &cb);
+			cmd.recno = -recno;
+			for_each_reflog_ent(ref, count_reflog_ent, &cmd);
 		} else {
-			cb.cmd.expire_total = approxidate(spec + 2);
-			for_each_reflog_ent(ref, count_reflog_ent, &cb);
-			cb.cmd.expire_total = 0;
+			cmd.expire_total = approxidate(spec + 2);
+			for_each_reflog_ent(ref, count_reflog_ent, &cmd);
+			cmd.expire_total = 0;
 		}
 
+		cb.cmd = cmd;
 		status |= reflog_expire(ref, flags,
 					reflog_expiry_prepare,
-					should_expire_reflog_ent,
+					should_prune_fn,
 					reflog_expiry_cleanup,
 					&cb);
 		free(ref);
diff --git a/builtin/repack.c b/builtin/repack.c
index 0b2d1e5..da1e364 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -258,9 +258,11 @@
 	for_each_packed_object(write_oid, &cmd,
 			       FOR_EACH_OBJECT_PROMISOR_ONLY);
 
-	if (cmd.in == -1)
+	if (cmd.in == -1) {
 		/* No packed objects; cmd was never started */
+		child_process_clear(&cmd);
 		return;
+	}
 
 	close(cmd.in);
 
@@ -610,7 +612,7 @@
 	struct tempfile *refs_snapshot = NULL;
 	int i, ext, ret;
 	FILE *out;
-	int show_progress = isatty(2);
+	int show_progress;
 
 	/* variables to be filled by option parsing */
 	int pack_everything = 0;
@@ -679,7 +681,7 @@
 
 	if (keep_unreachable &&
 	    (unpack_unreachable || (pack_everything & LOOSEN_UNREACHABLE)))
-		die(_("--keep-unreachable and -A are incompatible"));
+		die(_("options '%s' and '%s' cannot be used together"), "--keep-unreachable", "-A");
 
 	if (write_bitmaps < 0) {
 		if (!write_midx &&
@@ -691,7 +693,7 @@
 		write_bitmaps = 0;
 	}
 	if (pack_kept_objects < 0)
-		pack_kept_objects = write_bitmaps > 0;
+		pack_kept_objects = write_bitmaps > 0 && !write_midx;
 
 	if (write_bitmaps && !(pack_everything & ALL_INTO_ONE) && !write_midx)
 		die(_(incremental_bitmap_conflict_error));
@@ -710,7 +712,7 @@
 
 	if (geometric_factor) {
 		if (pack_everything)
-			die(_("--geometric is incompatible with -A, -a"));
+			die(_("options '%s' and '%s' cannot be used together"), "--geometric", "-A/-a");
 		init_pack_geometry(&geometry);
 		split_pack_geometry(geometry, geometric_factor);
 	}
@@ -723,6 +725,8 @@
 
 	prepare_pack_objects(&cmd, &po_args);
 
+	show_progress = !po_args.quiet && isatty(2);
+
 	strvec_push(&cmd.args, "--keep-true-parents");
 	if (!pack_kept_objects)
 		strvec_push(&cmd.args, "--honor-pack-keep");
@@ -842,7 +846,7 @@
 			fname_old = mkpathdup("%s-%s%s",
 					packtmp, item->string, exts[ext].name);
 
-			if (((uintptr_t)item->util) & (1 << ext)) {
+			if (((uintptr_t)item->util) & ((uintptr_t)1 << ext)) {
 				struct stat statbuffer;
 				if (!stat(fname_old, &statbuffer)) {
 					statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
@@ -924,7 +928,7 @@
 			}
 			strbuf_release(&buf);
 		}
-		if (!po_args.quiet && show_progress)
+		if (show_progress)
 			opts |= PRUNE_PACKED_VERBOSE;
 		prune_packed_objects(opts);
 
diff --git a/builtin/replace.c b/builtin/replace.c
index 946938d..6ff1734 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -258,11 +258,10 @@
 		return error_errno(_("unable to open %s for reading"), filename);
 
 	if (!raw && type == OBJ_TREE) {
-		const char *argv[] = { "mktree", NULL };
 		struct child_process cmd = CHILD_PROCESS_INIT;
 		struct strbuf result = STRBUF_INIT;
 
-		cmd.argv = argv;
+		strvec_push(&cmd.args, "mktree");
 		cmd.git_cmd = 1;
 		cmd.in = fd;
 		cmd.out = -1;
diff --git a/builtin/reset.c b/builtin/reset.c
index 7393595..b97745e 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -25,6 +25,7 @@
 #include "cache-tree.h"
 #include "submodule.h"
 #include "submodule-config.h"
+#include "dir.h"
 
 #define REFRESH_INDEX_DELAY_WARNING_IN_MS (2 * 1000)
 
@@ -136,21 +137,36 @@
 	int intent_to_add = *(int *)data;
 
 	for (i = 0; i < q->nr; i++) {
+		int pos;
 		struct diff_filespec *one = q->queue[i]->one;
-		int is_missing = !(one->mode && !is_null_oid(&one->oid));
+		int is_in_reset_tree = one->mode && !is_null_oid(&one->oid);
 		struct cache_entry *ce;
 
-		if (is_missing && !intent_to_add) {
+		if (!is_in_reset_tree && !intent_to_add) {
 			remove_file_from_cache(one->path);
 			continue;
 		}
 
 		ce = make_cache_entry(&the_index, one->mode, &one->oid, one->path,
 				      0, 0);
+
+		/*
+		 * If the file 1) corresponds to an existing index entry with
+		 * skip-worktree set, or 2) does not exist in the index but is
+		 * outside the sparse checkout definition, add a skip-worktree bit
+		 * to the new index entry. Note that a sparse index will be expanded
+		 * if this entry is outside the sparse cone - this is necessary
+		 * to properly construct the reset sparse directory.
+		 */
+		pos = cache_name_pos(one->path, strlen(one->path));
+		if ((pos >= 0 && ce_skip_worktree(active_cache[pos])) ||
+		    (pos < 0 && !path_in_sparse_checkout(one->path, &the_index)))
+			ce->ce_flags |= CE_SKIP_WORKTREE;
+
 		if (!ce)
 			die(_("make_cache_entry failed for path '%s'"),
 			    one->path);
-		if (is_missing) {
+		if (!is_in_reset_tree) {
 			ce->ce_flags |= CE_INTENT_TO_ADD;
 			set_object_name_for_intent_to_add_entry(ce);
 		}
@@ -158,6 +174,82 @@
 	}
 }
 
+static int pathspec_needs_expanded_index(const struct pathspec *pathspec)
+{
+	unsigned int i, pos;
+	int res = 0;
+	char *skip_worktree_seen = NULL;
+
+	/*
+	 * When using a magic pathspec, assume for the sake of simplicity that
+	 * the index needs to be expanded to match all matchable files.
+	 */
+	if (pathspec->magic)
+		return 1;
+
+	for (i = 0; i < pathspec->nr; i++) {
+		struct pathspec_item item = pathspec->items[i];
+
+		/*
+		 * If the pathspec item has a wildcard, the index should be expanded
+		 * if the pathspec has the possibility of matching a subset of entries inside
+		 * of a sparse directory (but not the entire directory).
+		 *
+		 * If the pathspec item is a literal path, the index only needs to be expanded
+		 * if a) the pathspec isn't in the sparse checkout cone (to make sure we don't
+		 * expand for in-cone files) and b) it doesn't match any sparse directories
+		 * (since we can reset whole sparse directories without expanding them).
+		 */
+		if (item.nowildcard_len < item.len) {
+			/*
+			 * Special case: if the pattern is a path inside the cone
+			 * followed by only wildcards, the pattern cannot match
+			 * partial sparse directories, so we don't expand the index.
+			 */
+			if (path_in_cone_mode_sparse_checkout(item.original, &the_index) &&
+			    strspn(item.original + item.nowildcard_len, "*") == item.len - item.nowildcard_len)
+				continue;
+
+			for (pos = 0; pos < active_nr; pos++) {
+				struct cache_entry *ce = active_cache[pos];
+
+				if (!S_ISSPARSEDIR(ce->ce_mode))
+					continue;
+
+				/*
+				 * If the pre-wildcard length is longer than the sparse
+				 * directory name and the sparse directory is the first
+				 * component of the pathspec, need to expand the index.
+				 */
+				if (item.nowildcard_len > ce_namelen(ce) &&
+				    !strncmp(item.original, ce->name, ce_namelen(ce))) {
+					res = 1;
+					break;
+				}
+
+				/*
+				 * If the pre-wildcard length is shorter than the sparse
+				 * directory and the pathspec does not match the whole
+				 * directory, need to expand the index.
+				 */
+				if (!strncmp(item.original, ce->name, item.nowildcard_len) &&
+				    wildmatch(item.original, ce->name, 0)) {
+					res = 1;
+					break;
+				}
+			}
+		} else if (!path_in_cone_mode_sparse_checkout(item.original, &the_index) &&
+			   !matches_skip_worktree(pathspec, i, &skip_worktree_seen))
+			res = 1;
+
+		if (res > 0)
+			break;
+	}
+
+	free(skip_worktree_seen);
+	return res;
+}
+
 static int read_from_tree(const struct pathspec *pathspec,
 			  struct object_id *tree_oid,
 			  int intent_to_add)
@@ -170,7 +262,13 @@
 	opt.format_callback = update_index_from_diff;
 	opt.format_callback_data = &intent_to_add;
 	opt.flags.override_submodule_config = 1;
+	opt.flags.recursive = 1;
 	opt.repo = the_repository;
+	opt.change = diff_change;
+	opt.add_remove = diff_addremove;
+
+	if (pathspec->nr && the_index.sparse_index && pathspec_needs_expanded_index(pathspec))
+		ensure_full_index(&the_index);
 
 	if (do_diff_cache(tree_oid, &opt))
 		return 1;
@@ -249,9 +347,6 @@
 	}
 	*rev_ret = rev;
 
-	if (read_cache() < 0)
-		die(_("index file corrupt"));
-
 	parse_pathspec(pathspec, 0,
 		       PATHSPEC_PREFER_FULL |
 		       (patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0),
@@ -328,16 +423,16 @@
 
 	if (pathspec_from_file) {
 		if (patch_mode)
-			die(_("--pathspec-from-file is incompatible with --patch"));
+			die(_("options '%s' and '%s' cannot be used together"), "--pathspec-from-file", "--patch");
 
 		if (pathspec.nr)
-			die(_("--pathspec-from-file is incompatible with pathspec arguments"));
+			die(_("'%s' and pathspec arguments cannot be used together"), "--pathspec-from-file");
 
 		parse_pathspec_file(&pathspec, 0,
 				    PATHSPEC_PREFER_FULL,
 				    prefix, pathspec_from_file, pathspec_file_nul);
 	} else if (pathspec_file_nul) {
-		die(_("--pathspec-file-nul requires --pathspec-from-file"));
+		die(_("the option '%s' requires '%s'"), "--pathspec-file-nul", "--pathspec-from-file");
 	}
 
 	unborn = !strcmp(rev, "HEAD") && get_oid("HEAD", &oid);
@@ -364,7 +459,7 @@
 
 	if (patch_mode) {
 		if (reset_type != NONE)
-			die(_("--patch is incompatible with --{hard,mixed,soft}"));
+			die(_("options '%s' and '%s' cannot be used together"), "--patch", "--{hard,mixed,soft}");
 		trace2_cmd_mode("patch-interactive");
 		return run_add_interactive(rev, "--patch=reset", &pathspec);
 	}
@@ -395,7 +490,13 @@
 		    _(reset_type_names[reset_type]));
 
 	if (intent_to_add && reset_type != MIXED)
-		die(_("-N can only be used with --mixed"));
+		die(_("the option '%s' requires '%s'"), "-N", "--mixed");
+
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
+	if (read_cache() < 0)
+		die(_("index file corrupt"));
 
 	/* Soft reset does not touch the index file nor the working tree
 	 * at all, but requires them in a good order.  Other resets reset
diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index 36cb909..777558e 100644
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -538,7 +538,7 @@
 		const char *arg = argv[i];
 		if (skip_prefix(arg, "--missing=", &arg)) {
 			if (revs.exclude_promisor_objects)
-				die(_("cannot combine --exclude-promisor-objects and --missing"));
+				die(_("options '%s' and '%s' cannot be used together"), "--exclude-promisor-objects", "--missing");
 			if (parse_missing_action_value(arg))
 				break;
 		}
@@ -676,7 +676,7 @@
 	if (revs.count &&
 	    (revs.tag_objects || revs.tree_objects || revs.blob_objects) &&
 	    (revs.left_right || revs.cherry_mark))
-		die(_("marked counting is incompatible with --objects"));
+		die(_("marked counting and '%s' cannot be used together"), "--objects");
 
 	save_commit_buffer = (revs.verbose_header ||
 			      revs.grep_filter.pattern_list ||
diff --git a/builtin/rm.c b/builtin/rm.c
index 3d0967c..84a935a 100644
--- a/builtin/rm.c
+++ b/builtin/rm.c
@@ -272,13 +272,13 @@
 
 	if (pathspec_from_file) {
 		if (pathspec.nr)
-			die(_("--pathspec-from-file is incompatible with pathspec arguments"));
+			die(_("'%s' and pathspec arguments cannot be used together"), "--pathspec-from-file");
 
 		parse_pathspec_file(&pathspec, 0,
 				    PATHSPEC_PREFER_CWD,
 				    prefix, pathspec_from_file, pathspec_file_nul);
 	} else if (pathspec_file_nul) {
-		die(_("--pathspec-file-nul requires --pathspec-from-file"));
+		die(_("the option '%s' requires '%s'"), "--pathspec-file-nul", "--pathspec-from-file");
 	}
 
 	if (!pathspec.nr)
@@ -399,12 +399,13 @@
 	if (!index_only) {
 		int removed = 0, gitmodules_modified = 0;
 		struct strbuf buf = STRBUF_INIT;
+		int flag = force ? REMOVE_DIR_PURGE_ORIGINAL_CWD : 0;
 		for (i = 0; i < list.nr; i++) {
 			const char *path = list.entry[i].name;
 			if (list.entry[i].is_submodule) {
 				strbuf_reset(&buf);
 				strbuf_addstr(&buf, path);
-				if (remove_dir_recursively(&buf, 0))
+				if (remove_dir_recursively(&buf, flag))
 					die(_("could not remove '%s'"), path);
 
 				removed = 1;
diff --git a/builtin/show-branch.c b/builtin/show-branch.c
index 0824492..e12c5e8 100644
--- a/builtin/show-branch.c
+++ b/builtin/show-branch.c
@@ -707,8 +707,8 @@
 			 *
 			 * Also --all and --remotes do not make sense either.
 			 */
-			die(_("--reflog is incompatible with --all, --remotes, "
-			      "--independent or --merge-base"));
+			die(_("options '%s' and '%s' cannot be used together"), "--reflog",
+				"--all/--remotes/--independent/--merge-base");
 	}
 
 	/* If nothing is specified, show all branches by default */
@@ -761,6 +761,7 @@
 			char *logmsg;
 			char *nth_desc;
 			const char *msg;
+			char *end;
 			timestamp_t timestamp;
 			int tz;
 
@@ -770,11 +771,12 @@
 				reflog = i;
 				break;
 			}
-			msg = strchr(logmsg, '\t');
-			if (!msg)
-				msg = "(none)";
-			else
-				msg++;
+
+			end = strchr(logmsg, '\n');
+			if (end)
+				*end = '\0';
+
+			msg = (*logmsg == '\0') ? "(none)" : logmsg;
 			reflog_msg[i] = xstrfmt("(%s) %s",
 						show_date(timestamp, tz,
 							  DATE_MODE(RELATIVE)),
diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index d0f5c47..679c107 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -56,6 +56,9 @@
 	char *sparse_filename;
 	int res;
 
+	if (!core_apply_sparse_checkout)
+		die(_("this worktree is not sparse"));
+
 	argc = parse_options(argc, argv, NULL,
 			     builtin_sparse_checkout_list_options,
 			     builtin_sparse_checkout_list_usage, 0);
@@ -380,6 +383,41 @@
 	return 0;
 }
 
+static int update_modes(int *cone_mode, int *sparse_index)
+{
+	int mode, record_mode;
+
+	/* Determine if we need to record the mode; ensure sparse checkout on */
+	record_mode = (*cone_mode != -1) || !core_apply_sparse_checkout;
+
+	/* If not specified, use previous definition of cone mode */
+	if (*cone_mode == -1 && core_apply_sparse_checkout)
+		*cone_mode = core_sparse_checkout_cone;
+
+	/* Set cone/non-cone mode appropriately */
+	core_apply_sparse_checkout = 1;
+	if (*cone_mode == 1) {
+		mode = MODE_CONE_PATTERNS;
+		core_sparse_checkout_cone = 1;
+	} else {
+		mode = MODE_ALL_PATTERNS;
+	}
+	if (record_mode && set_config(mode))
+		return 1;
+
+	/* Set sparse-index/non-sparse-index mode if specified */
+	if (*sparse_index >= 0) {
+		if (set_sparse_index_config(the_repository, *sparse_index) < 0)
+			die(_("failed to modify sparse-index config"));
+
+		/* force an index rewrite */
+		repo_read_index(the_repository);
+		the_repository->index->updated_workdir = 1;
+	}
+
+	return 0;
+}
+
 static char const * const builtin_sparse_checkout_init_usage[] = {
 	N_("git sparse-checkout init [--cone] [--[no-]sparse-index]"),
 	NULL
@@ -396,7 +434,6 @@
 	char *sparse_filename;
 	int res;
 	struct object_id oid;
-	int mode;
 	struct strbuf pattern = STRBUF_INIT;
 
 	static struct option builtin_sparse_checkout_init_options[] = {
@@ -409,19 +446,14 @@
 
 	repo_read_index(the_repository);
 
+	init_opts.cone_mode = -1;
 	init_opts.sparse_index = -1;
 
 	argc = parse_options(argc, argv, NULL,
 			     builtin_sparse_checkout_init_options,
 			     builtin_sparse_checkout_init_usage, 0);
 
-	if (init_opts.cone_mode) {
-		mode = MODE_CONE_PATTERNS;
-		core_sparse_checkout_cone = 1;
-	} else
-		mode = MODE_ALL_PATTERNS;
-
-	if (set_config(mode))
+	if (update_modes(&init_opts.cone_mode, &init_opts.sparse_index))
 		return 1;
 
 	memset(&pl, 0, sizeof(pl));
@@ -429,17 +461,6 @@
 	sparse_filename = get_sparse_checkout_filename();
 	res = add_patterns_from_file_to_list(sparse_filename, "", 0, &pl, NULL, 0);
 
-	if (init_opts.sparse_index >= 0) {
-		if (set_sparse_index_config(the_repository, init_opts.sparse_index) < 0)
-			die(_("failed to modify sparse-index config"));
-
-		/* force an index rewrite */
-		repo_read_index(the_repository);
-		the_repository->index->updated_workdir = 1;
-	}
-
-	core_apply_sparse_checkout = 1;
-
 	/* If we already have a sparse-checkout file, use it. */
 	if (res >= 0) {
 		free(sparse_filename);
@@ -483,7 +504,7 @@
 		char *oldpattern = e->pattern;
 		size_t newlen;
 
-		if (slash == e->pattern)
+		if (!slash || slash == e->pattern)
 			break;
 
 		newlen = slash - e->pattern;
@@ -515,17 +536,9 @@
 	insert_recursive_pattern(pl, line);
 }
 
-static char const * const builtin_sparse_checkout_set_usage[] = {
-	N_("git sparse-checkout (set|add) (--stdin | <patterns>)"),
-	NULL
-};
-
-static struct sparse_checkout_set_opts {
-	int use_stdin;
-} set_opts;
-
 static void add_patterns_from_input(struct pattern_list *pl,
-				    int argc, const char **argv)
+				    int argc, const char **argv,
+				    int use_stdin)
 {
 	int i;
 	if (core_sparse_checkout_cone) {
@@ -535,7 +548,7 @@
 		hashmap_init(&pl->parent_hashmap, pl_hashmap_cmp, NULL, 0);
 		pl->use_cone_patterns = 1;
 
-		if (set_opts.use_stdin) {
+		if (use_stdin) {
 			struct strbuf unquoted = STRBUF_INIT;
 			while (!strbuf_getline(&line, stdin)) {
 				if (line.buf[0] == '"') {
@@ -559,7 +572,7 @@
 			}
 		}
 	} else {
-		if (set_opts.use_stdin) {
+		if (use_stdin) {
 			struct strbuf line = STRBUF_INIT;
 
 			while (!strbuf_getline(&line, stdin)) {
@@ -580,7 +593,8 @@
 };
 
 static void add_patterns_cone_mode(int argc, const char **argv,
-				   struct pattern_list *pl)
+				   struct pattern_list *pl,
+				   int use_stdin)
 {
 	struct strbuf buffer = STRBUF_INIT;
 	struct pattern_entry *pe;
@@ -588,7 +602,7 @@
 	struct pattern_list existing;
 	char *sparse_filename = get_sparse_checkout_filename();
 
-	add_patterns_from_input(pl, argc, argv);
+	add_patterns_from_input(pl, argc, argv, use_stdin);
 
 	memset(&existing, 0, sizeof(existing));
 	existing.use_cone_patterns = core_sparse_checkout_cone;
@@ -598,6 +612,9 @@
 		die(_("unable to load existing sparse-checkout patterns"));
 	free(sparse_filename);
 
+	if (!existing.use_cone_patterns)
+		die(_("existing sparse-checkout patterns do not use cone mode"));
+
 	hashmap_for_each_entry(&existing.recursive_hashmap, &iter, pe, ent) {
 		if (!hashmap_contains_parent(&pl->recursive_hashmap,
 					pe->pattern, &buffer) ||
@@ -614,17 +631,19 @@
 }
 
 static void add_patterns_literal(int argc, const char **argv,
-				 struct pattern_list *pl)
+				 struct pattern_list *pl,
+				 int use_stdin)
 {
 	char *sparse_filename = get_sparse_checkout_filename();
 	if (add_patterns_from_file_to_list(sparse_filename, "", 0,
 					   pl, NULL, 0))
 		die(_("unable to load existing sparse-checkout patterns"));
 	free(sparse_filename);
-	add_patterns_from_input(pl, argc, argv);
+	add_patterns_from_input(pl, argc, argv, use_stdin);
 }
 
-static int modify_pattern_list(int argc, const char **argv, enum modify_type m)
+static int modify_pattern_list(int argc, const char **argv, int use_stdin,
+			       enum modify_type m)
 {
 	int result;
 	int changed_config = 0;
@@ -633,13 +652,13 @@
 	switch (m) {
 	case ADD:
 		if (core_sparse_checkout_cone)
-			add_patterns_cone_mode(argc, argv, pl);
+			add_patterns_cone_mode(argc, argv, pl, use_stdin);
 		else
-			add_patterns_literal(argc, argv, pl);
+			add_patterns_literal(argc, argv, pl, use_stdin);
 		break;
 
 	case REPLACE:
-		add_patterns_from_input(pl, argc, argv);
+		add_patterns_from_input(pl, argc, argv, use_stdin);
 		break;
 	}
 
@@ -659,41 +678,124 @@
 	return result;
 }
 
-static int sparse_checkout_set(int argc, const char **argv, const char *prefix,
-			       enum modify_type m)
+static char const * const builtin_sparse_checkout_add_usage[] = {
+	N_("git sparse-checkout add (--stdin | <patterns>)"),
+	NULL
+};
+
+static struct sparse_checkout_add_opts {
+	int use_stdin;
+} add_opts;
+
+static int sparse_checkout_add(int argc, const char **argv, const char *prefix)
 {
-	static struct option builtin_sparse_checkout_set_options[] = {
-		OPT_BOOL(0, "stdin", &set_opts.use_stdin,
+	static struct option builtin_sparse_checkout_add_options[] = {
+		OPT_BOOL(0, "stdin", &add_opts.use_stdin,
 			 N_("read patterns from standard in")),
 		OPT_END(),
 	};
 
+	if (!core_apply_sparse_checkout)
+		die(_("no sparse-checkout to add to"));
+
 	repo_read_index(the_repository);
 
 	argc = parse_options(argc, argv, prefix,
+			     builtin_sparse_checkout_add_options,
+			     builtin_sparse_checkout_add_usage,
+			     PARSE_OPT_KEEP_UNKNOWN);
+
+	return modify_pattern_list(argc, argv, add_opts.use_stdin, ADD);
+}
+
+static char const * const builtin_sparse_checkout_set_usage[] = {
+	N_("git sparse-checkout set [--[no-]cone] [--[no-]sparse-index] (--stdin | <patterns>)"),
+	NULL
+};
+
+static struct sparse_checkout_set_opts {
+	int cone_mode;
+	int sparse_index;
+	int use_stdin;
+} set_opts;
+
+static int sparse_checkout_set(int argc, const char **argv, const char *prefix)
+{
+	int default_patterns_nr = 2;
+	const char *default_patterns[] = {"/*", "!/*/", NULL};
+
+	static struct option builtin_sparse_checkout_set_options[] = {
+		OPT_BOOL(0, "cone", &set_opts.cone_mode,
+			 N_("initialize the sparse-checkout in cone mode")),
+		OPT_BOOL(0, "sparse-index", &set_opts.sparse_index,
+			 N_("toggle the use of a sparse index")),
+		OPT_BOOL_F(0, "stdin", &set_opts.use_stdin,
+			   N_("read patterns from standard in"),
+			   PARSE_OPT_NONEG),
+		OPT_END(),
+	};
+
+	repo_read_index(the_repository);
+
+	set_opts.cone_mode = -1;
+	set_opts.sparse_index = -1;
+
+	argc = parse_options(argc, argv, prefix,
 			     builtin_sparse_checkout_set_options,
 			     builtin_sparse_checkout_set_usage,
 			     PARSE_OPT_KEEP_UNKNOWN);
 
-	return modify_pattern_list(argc, argv, m);
+	if (update_modes(&set_opts.cone_mode, &set_opts.sparse_index))
+		return 1;
+
+	/*
+	 * Cone mode automatically specifies the toplevel directory.  For
+	 * non-cone mode, if nothing is specified, manually select just the
+	 * top-level directory (much as 'init' would do).
+	 */
+	if (!core_sparse_checkout_cone && argc == 0) {
+		argv = default_patterns;
+		argc = default_patterns_nr;
+	}
+
+	return modify_pattern_list(argc, argv, set_opts.use_stdin, REPLACE);
 }
 
 static char const * const builtin_sparse_checkout_reapply_usage[] = {
-	N_("git sparse-checkout reapply"),
+	N_("git sparse-checkout reapply [--[no-]cone] [--[no-]sparse-index]"),
 	NULL
 };
 
+static struct sparse_checkout_reapply_opts {
+	int cone_mode;
+	int sparse_index;
+} reapply_opts;
+
 static int sparse_checkout_reapply(int argc, const char **argv)
 {
 	static struct option builtin_sparse_checkout_reapply_options[] = {
+		OPT_BOOL(0, "cone", &reapply_opts.cone_mode,
+			 N_("initialize the sparse-checkout in cone mode")),
+		OPT_BOOL(0, "sparse-index", &reapply_opts.sparse_index,
+			 N_("toggle the use of a sparse index")),
 		OPT_END(),
 	};
 
+	if (!core_apply_sparse_checkout)
+		die(_("must be in a sparse-checkout to reapply sparsity patterns"));
+
 	argc = parse_options(argc, argv, NULL,
 			     builtin_sparse_checkout_reapply_options,
 			     builtin_sparse_checkout_reapply_usage, 0);
 
 	repo_read_index(the_repository);
+
+	reapply_opts.cone_mode = -1;
+	reapply_opts.sparse_index = -1;
+
+	if (update_modes(&reapply_opts.cone_mode, &reapply_opts.sparse_index))
+		return 1;
+
 	return update_working_directory(NULL);
 }
 
@@ -710,6 +812,17 @@
 	struct pattern_list pl;
 	struct strbuf match_all = STRBUF_INIT;
 
+	/*
+	 * We do not exit early if !core_apply_sparse_checkout; due to the
+	 * ability for users to manually muck things up between
+	 *   direct editing of .git/info/sparse-checkout
+	 *   running read-tree -m u HEAD or update-index --skip-worktree
+	 *   direct toggling of config options
+	 * users might end up with an index with SKIP_WORKTREE bit set on
+	 * some files and not know how to undo it.  So, here we just
+	 * forcibly return to a dense checkout regardless of initial state.
+	 */
+
 	argc = parse_options(argc, argv, NULL,
 			     builtin_sparse_checkout_disable_options,
 			     builtin_sparse_checkout_disable_usage, 0);
@@ -758,9 +871,9 @@
 		if (!strcmp(argv[0], "init"))
 			return sparse_checkout_init(argc, argv);
 		if (!strcmp(argv[0], "set"))
-			return sparse_checkout_set(argc, argv, prefix, REPLACE);
+			return sparse_checkout_set(argc, argv, prefix);
 		if (!strcmp(argv[0], "add"))
-			return sparse_checkout_set(argc, argv, prefix, ADD);
+			return sparse_checkout_add(argc, argv, prefix);
 		if (!strcmp(argv[0], "reapply"))
 			return sparse_checkout_reapply(argc, argv);
 		if (!strcmp(argv[0], "disable"))
diff --git a/builtin/stash.c b/builtin/stash.c
index a0ccc86..1ef2017 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -27,11 +27,11 @@
 	N_("git stash ( pop | apply ) [--index] [-q|--quiet] [<stash>]"),
 	N_("git stash branch <branchname> [<stash>]"),
 	"git stash clear",
-	N_("git stash [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
+	N_("git stash [push [-p|--patch] [-S|--staged] [-k|--[no-]keep-index] [-q|--quiet]\n"
 	   "          [-u|--include-untracked] [-a|--all] [-m|--message <message>]\n"
 	   "          [--pathspec-from-file=<file> [--pathspec-file-nul]]\n"
 	   "          [--] [<pathspec>...]]"),
-	N_("git stash save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
+	N_("git stash save [-p|--patch] [-S|--staged] [-k|--[no-]keep-index] [-q|--quiet]\n"
 	   "          [-u|--include-untracked] [-a|--all] [<message>]"),
 	NULL
 };
@@ -561,18 +561,19 @@
 		if (index)
 			fprintf_ln(stderr, _("Index was not unstashed."));
 
-		return ret;
+		goto restore_untracked;
 	}
 
 	if (has_index) {
 		if (reset_tree(&index_tree, 0, 0))
-			return -1;
+			ret = -1;
 	} else {
 		unstage_changes_unless_new(&c_tree);
 	}
 
+restore_untracked:
 	if (info->has_u && restore_untracked(&info->u_tree))
-		return error(_("could not restore untracked files from stash"));
+		ret = error(_("could not restore untracked files from stash"));
 
 	if (!quiet) {
 		struct child_process cp = CHILD_PROCESS_INIT;
@@ -592,7 +593,7 @@
 		run_command(&cp);
 	}
 
-	return 0;
+	return ret;
 }
 
 static int apply_stash(int argc, const char **argv, const char *prefix)
@@ -1132,6 +1133,38 @@
 	return ret;
 }
 
+static int stash_staged(struct stash_info *info, struct strbuf *out_patch,
+			int quiet)
+{
+	int ret = 0;
+	struct child_process cp_diff_tree = CHILD_PROCESS_INIT;
+	struct index_state istate = { NULL };
+
+	if (write_index_as_tree(&info->w_tree, &istate, the_repository->index_file,
+				0, NULL)) {
+		ret = -1;
+		goto done;
+	}
+
+	cp_diff_tree.git_cmd = 1;
+	strvec_pushl(&cp_diff_tree.args, "diff-tree", "-p", "-U1", "HEAD",
+		     oid_to_hex(&info->w_tree), "--", NULL);
+	if (pipe_command(&cp_diff_tree, NULL, 0, out_patch, 0, NULL, 0)) {
+		ret = -1;
+		goto done;
+	}
+
+	if (!out_patch->len) {
+		if (!quiet)
+			fprintf_ln(stderr, _("No staged changes"));
+		ret = 1;
+	}
+
+done:
+	discard_index(&istate);
+	return ret;
+}
+
 static int stash_patch(struct stash_info *info, const struct pathspec *ps,
 		       struct strbuf *out_patch, int quiet)
 {
@@ -1258,7 +1291,7 @@
 }
 
 static int do_create_stash(const struct pathspec *ps, struct strbuf *stash_msg_buf,
-			   int include_untracked, int patch_mode,
+			   int include_untracked, int patch_mode, int only_staged,
 			   struct stash_info *info, struct strbuf *patch,
 			   int quiet)
 {
@@ -1337,6 +1370,16 @@
 		} else if (ret > 0) {
 			goto done;
 		}
+	} else if (only_staged) {
+		ret = stash_staged(info, patch, quiet);
+		if (ret < 0) {
+			if (!quiet)
+				fprintf_ln(stderr, _("Cannot save the current "
+						     "staged state"));
+			goto done;
+		} else if (ret > 0) {
+			goto done;
+		}
 	} else {
 		if (stash_working_tree(info, ps)) {
 			if (!quiet)
@@ -1395,7 +1438,7 @@
 	if (!check_changes_tracked_files(&ps))
 		return 0;
 
-	ret = do_create_stash(&ps, &stash_msg_buf, 0, 0, &info,
+	ret = do_create_stash(&ps, &stash_msg_buf, 0, 0, 0, &info,
 			      NULL, 0);
 	if (!ret)
 		printf_ln("%s", oid_to_hex(&info.w_commit));
@@ -1405,7 +1448,7 @@
 }
 
 static int do_push_stash(const struct pathspec *ps, const char *stash_msg, int quiet,
-			 int keep_index, int patch_mode, int include_untracked)
+			 int keep_index, int patch_mode, int include_untracked, int only_staged)
 {
 	int ret = 0;
 	struct stash_info info;
@@ -1423,6 +1466,17 @@
 		goto done;
 	}
 
+	/* --patch overrides --staged */
+	if (patch_mode)
+		only_staged = 0;
+
+	if (only_staged && include_untracked) {
+		fprintf_ln(stderr, _("Can't use --staged and --include-untracked"
+				     " or --all at the same time"));
+		ret = -1;
+		goto done;
+	}
+
 	read_cache_preload(NULL);
 	if (!include_untracked && ps->nr) {
 		int i;
@@ -1463,7 +1517,7 @@
 
 	if (stash_msg)
 		strbuf_addstr(&stash_msg_buf, stash_msg);
-	if (do_create_stash(ps, &stash_msg_buf, include_untracked, patch_mode,
+	if (do_create_stash(ps, &stash_msg_buf, include_untracked, patch_mode, only_staged,
 			    &info, &patch, quiet)) {
 		ret = -1;
 		goto done;
@@ -1480,13 +1534,15 @@
 		printf_ln(_("Saved working directory and index state %s"),
 			  stash_msg_buf.buf);
 
-	if (!patch_mode) {
+	if (!(patch_mode || only_staged)) {
 		if (include_untracked && !ps->nr) {
 			struct child_process cp = CHILD_PROCESS_INIT;
 
 			cp.git_cmd = 1;
+			if (startup_info->original_cwd)
+				cp.dir = startup_info->original_cwd;
 			strvec_pushl(&cp.args, "clean", "--force",
-				     "--quiet", "-d", NULL);
+				     "--quiet", "-d", ":/", NULL);
 			if (include_untracked == INCLUDE_ALL_FILES)
 				strvec_push(&cp.args, "-x");
 			if (run_command(&cp)) {
@@ -1598,6 +1654,7 @@
 {
 	int force_assume = 0;
 	int keep_index = -1;
+	int only_staged = 0;
 	int patch_mode = 0;
 	int include_untracked = 0;
 	int quiet = 0;
@@ -1608,6 +1665,8 @@
 	struct option options[] = {
 		OPT_BOOL('k', "keep-index", &keep_index,
 			 N_("keep index")),
+		OPT_BOOL('S', "staged", &only_staged,
+			 N_("stash staged changes only")),
 		OPT_BOOL('p', "patch", &patch_mode,
 			 N_("stash in patch mode")),
 		OPT__QUIET(&quiet, N_("quiet mode")),
@@ -1625,6 +1684,7 @@
 	if (argc) {
 		force_assume = !strcmp(argv[0], "-p");
 		argc = parse_options(argc, argv, prefix, options,
+				     push_assumed ? git_stash_usage :
 				     git_stash_push_usage,
 				     PARSE_OPT_KEEP_DASHDASH);
 	}
@@ -1644,25 +1704,29 @@
 
 	if (pathspec_from_file) {
 		if (patch_mode)
-			die(_("--pathspec-from-file is incompatible with --patch"));
+			die(_("options '%s' and '%s' cannot be used together"), "--pathspec-from-file", "--patch");
+
+		if (only_staged)
+			die(_("options '%s' and '%s' cannot be used together"), "--pathspec-from-file", "--staged");
 
 		if (ps.nr)
-			die(_("--pathspec-from-file is incompatible with pathspec arguments"));
+			die(_("'%s' and pathspec arguments cannot be used together"), "--pathspec-from-file");
 
 		parse_pathspec_file(&ps, 0,
 				    PATHSPEC_PREFER_FULL | PATHSPEC_PREFIX_ORIGIN,
 				    prefix, pathspec_from_file, pathspec_file_nul);
 	} else if (pathspec_file_nul) {
-		die(_("--pathspec-file-nul requires --pathspec-from-file"));
+		die(_("the option '%s' requires '%s'"), "--pathspec-file-nul", "--pathspec-from-file");
 	}
 
 	return do_push_stash(&ps, stash_msg, quiet, keep_index, patch_mode,
-			     include_untracked);
+			     include_untracked, only_staged);
 }
 
 static int save_stash(int argc, const char **argv, const char *prefix)
 {
 	int keep_index = -1;
+	int only_staged = 0;
 	int patch_mode = 0;
 	int include_untracked = 0;
 	int quiet = 0;
@@ -1673,6 +1737,8 @@
 	struct option options[] = {
 		OPT_BOOL('k', "keep-index", &keep_index,
 			 N_("keep index")),
+		OPT_BOOL('S', "staged", &only_staged,
+			 N_("stash staged changes only")),
 		OPT_BOOL('p', "patch", &patch_mode,
 			 N_("stash in patch mode")),
 		OPT__QUIET(&quiet, N_("quiet mode")),
@@ -1694,7 +1760,7 @@
 
 	memset(&ps, 0, sizeof(ps));
 	ret = do_push_stash(&ps, stash_msg, quiet, keep_index,
-			    patch_mode, include_untracked);
+			    patch_mode, include_untracked, only_staged);
 
 	strbuf_release(&stash_msg_buf);
 	return ret;
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index e630f0c..c5d3fc3 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -1313,7 +1313,7 @@
 
 	if (files) {
 		if (cached)
-			die(_("--cached and --files are mutually exclusive"));
+			die(_("options '%s' and '%s' cannot be used together"), "--cached", "--files");
 		diff_cmd = DIFF_FILES;
 	}
 
@@ -1503,16 +1503,17 @@
 		struct strbuf sb_rm = STRBUF_INIT;
 		const char *format;
 
-		/*
-		 * protect submodules containing a .git directory
-		 * NEEDSWORK: instead of dying, automatically call
-		 * absorbgitdirs and (possibly) warn.
-		 */
-		if (is_directory(sub_git_dir))
-			die(_("Submodule work tree '%s' contains a .git "
-			      "directory (use 'rm -rf' if you really want "
-			      "to remove it including all of its history)"),
-			    displaypath);
+		if (is_directory(sub_git_dir)) {
+			if (!(flags & OPT_QUIET))
+				warning(_("Submodule work tree '%s' contains a .git "
+					  "directory. This will be replaced with a "
+					  ".git file by using absorbgitdirs."),
+					displaypath);
+
+			absorb_git_dir_into_superproject(path,
+							 ABSORB_GITDIR_RECURSE_SUBMODULES);
+
+		}
 
 		if (!(flags & OPT_FORCE)) {
 			struct child_process cp_rm = CHILD_PROCESS_INIT;
@@ -2971,7 +2972,7 @@
 		die(_("--branch or --default required"));
 
 	if (opt_branch && opt_default)
-		die(_("--branch and --default are mutually exclusive"));
+		die(_("options '%s' and '%s' cannot be used together"), "--branch", "--default");
 
 	if (argc != 1 || !(path = argv[0]))
 		usage_with_options(usage, options);
diff --git a/builtin/tag.c b/builtin/tag.c
index 6fe6467..134b3f1 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -178,7 +178,6 @@
 static int git_tag_config(const char *var, const char *value, void *cb)
 {
 	int status;
-	struct ref_sorting **sorting_tail = (struct ref_sorting **)cb;
 
 	if (!strcmp(var, "tag.gpgsign")) {
 		config_sign_tag = git_config_bool(var, value);
@@ -188,7 +187,7 @@
 	if (!strcmp(var, "tag.sort")) {
 		if (!value)
 			return config_error_nonbool(var);
-		parse_ref_sorting(sorting_tail, value);
+		string_list_append(cb, value);
 		return 0;
 	}
 
@@ -436,7 +435,8 @@
 	struct ref_transaction *transaction;
 	struct strbuf err = STRBUF_INIT;
 	struct ref_filter filter;
-	static struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
+	struct ref_sorting *sorting;
+	struct string_list sorting_options = STRING_LIST_INIT_DUP;
 	struct ref_format format = REF_FORMAT_INIT;
 	int icase = 0;
 	int edit_flag = 0;
@@ -470,7 +470,7 @@
 		OPT_WITHOUT(&filter.no_commit, N_("print only tags that don't contain the commit")),
 		OPT_MERGED(&filter, N_("print only tags that are merged")),
 		OPT_NO_MERGED(&filter, N_("print only tags that are not merged")),
-		OPT_REF_SORT(sorting_tail),
+		OPT_REF_SORT(&sorting_options),
 		{
 			OPTION_CALLBACK, 0, "points-at", &filter.points_at, N_("object"),
 			N_("print only tags of the object"), PARSE_OPT_LASTARG_DEFAULT,
@@ -483,10 +483,11 @@
 		OPT_END()
 	};
 	int ret = 0;
+	const char *only_in_list = NULL;
 
 	setup_ref_filter_porcelain_msg();
 
-	git_config(git_tag_config, sorting_tail);
+	git_config(git_tag_config, &sorting_options);
 
 	memset(&opt, 0, sizeof(opt));
 	memset(&filter, 0, sizeof(filter));
@@ -522,11 +523,10 @@
 	finalize_colopts(&colopts, -1);
 	if (cmdmode == 'l' && filter.lines != -1) {
 		if (explicitly_enable_column(colopts))
-			die(_("--column and -n are incompatible"));
+			die(_("options '%s' and '%s' cannot be used together"), "--column", "-n");
 		colopts = 0;
 	}
-	if (!sorting)
-		sorting = ref_default_sorting();
+	sorting = ref_sorting_options(&sorting_options);
 	ref_sorting_set_sort_flags_all(sorting, REF_SORTING_ICASE, icase);
 	filter.ignore_case = icase;
 	if (cmdmode == 'l') {
@@ -543,15 +543,19 @@
 		goto cleanup;
 	}
 	if (filter.lines != -1)
-		die(_("-n option is only allowed in list mode"));
-	if (filter.with_commit)
-		die(_("--contains option is only allowed in list mode"));
-	if (filter.no_commit)
-		die(_("--no-contains option is only allowed in list mode"));
-	if (filter.points_at.nr)
-		die(_("--points-at option is only allowed in list mode"));
-	if (filter.reachable_from || filter.unreachable_from)
-		die(_("--merged and --no-merged options are only allowed in list mode"));
+		only_in_list = "-n";
+	else if (filter.with_commit)
+		only_in_list = "--contains";
+	else if (filter.no_commit)
+		only_in_list = "--no-contains";
+	else if (filter.points_at.nr)
+		only_in_list = "--points-at";
+	else if (filter.reachable_from)
+		only_in_list = "--merged";
+	else if (filter.unreachable_from)
+		only_in_list = "--no-merged";
+	if (only_in_list)
+		die(_("the '%s' option is only allowed in list mode"), only_in_list);
 	if (cmdmode == 'd') {
 		ret = delete_tags(argv);
 		goto cleanup;
@@ -565,7 +569,7 @@
 
 	if (msg.given || msgfile) {
 		if (msg.given && msgfile)
-			die(_("only one -F or -m option is allowed."));
+			die(_("options '%s' and '%s' cannot be used together"), "-F", "-m");
 		if (msg.given)
 			strbuf_addbuf(&buf, &(msg.buf));
 		else {
diff --git a/builtin/upload-archive.c b/builtin/upload-archive.c
index 24654b4..98d028d 100644
--- a/builtin/upload-archive.c
+++ b/builtin/upload-archive.c
@@ -77,7 +77,7 @@
 
 int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 {
-	struct child_process writer = { argv };
+	struct child_process writer = CHILD_PROCESS_INIT;
 
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage(upload_archive_usage);
@@ -89,9 +89,10 @@
 	 * multiplexed out to our fd#1.  If the child dies, we tell the other
 	 * end over channel #3.
 	 */
-	argv[0] = "upload-archive--writer";
 	writer.out = writer.err = -1;
 	writer.git_cmd = 1;
+	strvec_push(&writer.args, "upload-archive--writer");
+	strvec_pushv(&writer.args, argv + 1);
 	if (start_command(&writer)) {
 		int err = errno;
 		packet_write_fmt(1, "NACK unable to spawn subprocess\n");
diff --git a/builtin/var.c b/builtin/var.c
index 6c6f46b..491db27 100644
--- a/builtin/var.c
+++ b/builtin/var.c
@@ -5,6 +5,7 @@
  */
 #include "builtin.h"
 #include "config.h"
+#include "refs.h"
 
 static const char var_usage[] = "git var (-l | <variable>)";
 
@@ -27,6 +28,11 @@
 	return pgm;
 }
 
+static const char *default_branch(int flag)
+{
+	return git_default_branch_name(1);
+}
+
 struct git_var {
 	const char *name;
 	const char *(*read)(int);
@@ -36,6 +42,7 @@
 	{ "GIT_AUTHOR_IDENT",   git_author_info },
 	{ "GIT_EDITOR", editor },
 	{ "GIT_PAGER", pager },
+	{ "GIT_DEFAULT_BRANCH", default_branch },
 	{ "", NULL },
 };
 
diff --git a/builtin/worktree.c b/builtin/worktree.c
index d22ece9..2838254 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -72,7 +72,7 @@
 static void prune_worktree(const char *id, const char *reason)
 {
 	if (show_only || verbose)
-		printf_ln(_("Removing %s/%s: %s"), "worktrees", id, reason);
+		fprintf_ln(stderr, _("Removing %s/%s: %s"), "worktrees", id, reason);
 	if (!show_only)
 		delete_git_dir(id);
 }
@@ -349,18 +349,18 @@
 			strvec_push(&cp.args, "--quiet");
 	}
 
-	cp.env = child_env.v;
+	strvec_pushv(&cp.env_array, child_env.v);
 	ret = run_command(&cp);
 	if (ret)
 		goto done;
 
 	if (opts->checkout) {
-		cp.argv = NULL;
-		strvec_clear(&cp.args);
+		struct child_process cp = CHILD_PROCESS_INIT;
+		cp.git_cmd = 1;
 		strvec_pushl(&cp.args, "reset", "--hard", "--no-recurse-submodules", NULL);
 		if (opts->quiet)
 			strvec_push(&cp.args, "--quiet");
-		cp.env = child_env.v;
+		strvec_pushv(&cp.env_array, child_env.v);
 		ret = run_command(&cp);
 		if (ret)
 			goto done;
@@ -385,12 +385,11 @@
 		const char *hook = find_hook("post-checkout");
 		if (hook) {
 			const char *env[] = { "GIT_DIR", "GIT_WORK_TREE", NULL };
-			cp.git_cmd = 0;
+			struct child_process cp = CHILD_PROCESS_INIT;
 			cp.no_stdin = 1;
 			cp.stdout_to_stderr = 1;
 			cp.dir = path;
-			cp.env = env;
-			cp.argv = NULL;
+			strvec_pushv(&cp.env_array, env);
 			cp.trace2_hook_name = "post-checkout";
 			strvec_pushl(&cp.args, absolute_path(hook),
 				     oid_to_hex(null_oid()),
@@ -418,24 +417,24 @@
 	if (force_new_branch) {
 		struct commit *commit = lookup_commit_reference_by_name(new_branch);
 		if (!commit)
-			printf_ln(_("Preparing worktree (new branch '%s')"), new_branch);
+			fprintf_ln(stderr, _("Preparing worktree (new branch '%s')"), new_branch);
 		else
-			printf_ln(_("Preparing worktree (resetting branch '%s'; was at %s)"),
+			fprintf_ln(stderr, _("Preparing worktree (resetting branch '%s'; was at %s)"),
 				  new_branch,
 				  find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 	} else if (new_branch) {
-		printf_ln(_("Preparing worktree (new branch '%s')"), new_branch);
+		fprintf_ln(stderr, _("Preparing worktree (new branch '%s')"), new_branch);
 	} else {
 		struct strbuf s = STRBUF_INIT;
 		if (!detach && !strbuf_check_branch_ref(&s, branch) &&
 		    ref_exists(s.buf))
-			printf_ln(_("Preparing worktree (checking out '%s')"),
+			fprintf_ln(stderr, _("Preparing worktree (checking out '%s')"),
 				  branch);
 		else {
 			struct commit *commit = lookup_commit_reference_by_name(branch);
 			if (!commit)
 				die(_("invalid reference: %s"), branch);
-			printf_ln(_("Preparing worktree (detached HEAD %s)"),
+			fprintf_ln(stderr, _("Preparing worktree (detached HEAD %s)"),
 				  find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 		}
 		strbuf_release(&s);
@@ -504,9 +503,9 @@
 	opts.checkout = 1;
 	ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
 	if (!!opts.detach + !!new_branch + !!new_branch_force > 1)
-		die(_("-b, -B, and --detach are mutually exclusive"));
+		die(_("options '%s', '%s', and '%s' cannot be used together"), "-b", "-B", "--detach");
 	if (lock_reason && !keep_locked)
-		die(_("--reason requires --lock"));
+		die(_("the option '%s' requires '%s'"), "--reason", "--lock");
 	if (lock_reason)
 		opts.keep_locked = lock_reason;
 	else if (keep_locked)
@@ -700,7 +699,7 @@
 	if (ac)
 		usage_with_options(worktree_usage, options);
 	else if (verbose && porcelain)
-		die(_("--verbose and --porcelain are mutually exclusive"));
+		die(_("options '%s' and '%s' cannot be used together"), "--verbose", "--porcelain");
 	else {
 		struct worktree **worktrees = get_worktrees();
 		int path_maxlen = 0, abbrev = DEFAULT_ABBREV, i;
@@ -1006,7 +1005,7 @@
 static void report_repair(int iserr, const char *path, const char *msg, void *cb_data)
 {
 	if (!iserr) {
-		printf_ln(_("repair: %s: %s"), msg, path);
+		fprintf_ln(stderr, _("repair: %s: %s"), msg, path);
 	} else {
 		int *exit_status = (int *)cb_data;
 		fprintf_ln(stderr, _("error: %s: %s"), msg, path);
diff --git a/cache-tree.c b/cache-tree.c
index 79d1681..65ca993 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -741,15 +741,26 @@
 	return ret;
 }
 
+static void prime_cache_tree_sparse_dir(struct cache_tree *it,
+					struct tree *tree)
+{
+
+	oidcpy(&it->oid, &tree->object.oid);
+	it->entry_count = 1;
+}
+
 static void prime_cache_tree_rec(struct repository *r,
 				 struct cache_tree *it,
-				 struct tree *tree)
+				 struct tree *tree,
+				 struct strbuf *tree_path)
 {
 	struct tree_desc desc;
 	struct name_entry entry;
 	int cnt;
+	int base_path_len = tree_path->len;
 
 	oidcpy(&it->oid, &tree->object.oid);
+
 	init_tree_desc(&desc, tree->buffer, tree->size);
 	cnt = 0;
 	while (tree_entry(&desc, &entry)) {
@@ -758,14 +769,40 @@
 		else {
 			struct cache_tree_sub *sub;
 			struct tree *subtree = lookup_tree(r, &entry.oid);
+
 			if (!subtree->object.parsed)
 				parse_tree(subtree);
 			sub = cache_tree_sub(it, entry.path);
 			sub->cache_tree = cache_tree();
-			prime_cache_tree_rec(r, sub->cache_tree, subtree);
+
+			/*
+			 * Recursively-constructed subtree path is only needed when working
+			 * in a sparse index (where it's used to determine whether the
+			 * subtree is a sparse directory in the index).
+			 */
+			if (r->index->sparse_index) {
+				strbuf_setlen(tree_path, base_path_len);
+				strbuf_grow(tree_path, base_path_len + entry.pathlen + 1);
+				strbuf_add(tree_path, entry.path, entry.pathlen);
+				strbuf_addch(tree_path, '/');
+			}
+
+			/*
+			 * If a sparse index is in use, the directory being processed may be
+			 * sparse. To confirm that, we can check whether an entry with that
+			 * exact name exists in the index. If it does, the created subtree
+			 * should be sparse. Otherwise, cache tree expansion should continue
+			 * as normal.
+			 */
+			if (r->index->sparse_index &&
+			    index_entry_exists(r->index, tree_path->buf, tree_path->len))
+				prime_cache_tree_sparse_dir(sub->cache_tree, subtree);
+			else
+				prime_cache_tree_rec(r, sub->cache_tree, subtree, tree_path);
 			cnt += sub->cache_tree->entry_count;
 		}
 	}
+
 	it->entry_count = cnt;
 }
 
@@ -773,11 +810,14 @@
 		      struct index_state *istate,
 		      struct tree *tree)
 {
+	struct strbuf tree_path = STRBUF_INIT;
+
 	trace2_region_enter("cache-tree", "prime_cache_tree", the_repository);
 	cache_tree_free(&istate->cache_tree);
 	istate->cache_tree = cache_tree();
 
-	prime_cache_tree_rec(r, istate->cache_tree, tree);
+	prime_cache_tree_rec(r, istate->cache_tree, tree, &tree_path);
+	strbuf_release(&tree_path);
 	istate->cache_changed |= CACHE_TREE_CHANGED;
 	trace2_region_leave("cache-tree", "prime_cache_tree", the_repository);
 }
diff --git a/cache.h b/cache.h
index eba1248..281f00a 100644
--- a/cache.h
+++ b/cache.h
@@ -350,8 +350,6 @@
 void remove_name_hash(struct index_state *istate, struct cache_entry *ce);
 void free_name_hash(struct index_state *istate);
 
-void ensure_full_index(struct index_state *istate);
-
 /* Cache entry creation and cleanup */
 
 /*
@@ -817,6 +815,16 @@
 int index_name_pos(struct index_state *, const char *name, int namelen);
 
 /*
+ * Determines whether an entry with the given name exists within the
+ * given index. The return value is 1 if an exact match is found, otherwise
+ * it is 0. Note that, unlike index_name_pos, this function does not expand
+ * the index if it is sparse. If an item exists within the full index but it
+ * is contained within a sparse directory (and not in the sparse index), 0 is
+ * returned.
+ */
+int index_entry_exists(struct index_state *, const char *name, int namelen);
+
+/*
  * Some functions return the negative complement of an insert position when a
  * precise match was not found but a position was found where the entry would
  * need to be inserted. This helper protects that logic from any integer
@@ -986,6 +994,7 @@
 extern char *git_replace_ref_base;
 
 extern int fsync_object_files;
+extern int use_fsync;
 extern int core_preload_index;
 extern int precomposed_unicode;
 extern int protect_hfs;
@@ -1588,6 +1597,7 @@
 timestamp_t approxidate_relative(const char *date);
 void parse_date_format(const char *format, struct date_mode *mode);
 int date_overflows(timestamp_t date);
+time_t tm_to_time_t(const struct tm *tm);
 
 #define IDENT_STRICT	       1
 #define IDENT_NO_DATE	       2
@@ -1834,8 +1844,10 @@
 struct startup_info {
 	int have_repository;
 	const char *prefix;
+	const char *original_cwd;
 };
 extern struct startup_info *startup_info;
+extern const char *tmp_original_cwd;
 
 /* merge.c */
 struct commit_list;
diff --git a/cbtree.c b/cbtree.c
index b0c65d8..336e46d 100644
--- a/cbtree.c
+++ b/cbtree.c
@@ -95,38 +95,6 @@
 	return p && !memcmp(p->k, k, klen) ? p : NULL;
 }
 
-struct cb_node *cb_unlink(struct cb_tree *t, const uint8_t *k, size_t klen)
-{
-	struct cb_node **wherep = &t->root;
-	struct cb_node **whereq = NULL;
-	struct cb_node *q = NULL;
-	size_t direction = 0;
-	uint8_t c;
-	struct cb_node *p = t->root;
-
-	if (!p) return NULL;	/* empty tree, nothing to delete */
-
-	/* traverse to find best match, keeping link to parent */
-	while (1 & (uintptr_t)p) {
-		whereq = wherep;
-		q = cb_node_of(p);
-		c = q->byte < klen ? k[q->byte] : 0;
-		direction = (1 + (q->otherbits | c)) >> 8;
-		wherep = q->child + direction;
-		p = *wherep;
-	}
-
-	if (memcmp(p->k, k, klen))
-		return NULL;		/* no match, nothing unlinked */
-
-	/* found an exact match */
-	if (whereq)	/* update parent */
-		*whereq = q->child[1 - direction];
-	else
-		t->root = NULL;
-	return p;
-}
-
 static enum cb_next cb_descend(struct cb_node *p, cb_iter fn, void *arg)
 {
 	if (1 & (uintptr_t)p) {
diff --git a/cbtree.h b/cbtree.h
index dedbb8e..0be14fb 100644
--- a/cbtree.h
+++ b/cbtree.h
@@ -47,7 +47,6 @@
 
 struct cb_node *cb_lookup(struct cb_tree *, const uint8_t *k, size_t klen);
 struct cb_node *cb_insert(struct cb_tree *, struct cb_node *, size_t klen);
-struct cb_node *cb_unlink(struct cb_tree *t, const uint8_t *k, size_t klen);
 
 typedef enum cb_next (*cb_iter)(struct cb_node *, void *arg);
 
diff --git a/ci/check-directional-formatting.bash b/ci/check-directional-formatting.bash
new file mode 100755
index 0000000..e6211b1
--- /dev/null
+++ b/ci/check-directional-formatting.bash
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+# This script verifies that the non-binary files tracked in the Git index do
+# not contain any Unicode directional formatting: such formatting could be used
+# to deceive reviewers into interpreting code differently from the compiler.
+# This is intended to run on an Ubuntu agent in a GitHub workflow.
+#
+# To allow translated messages to introduce such directional formatting in the
+# future, we exclude the `.po` files from this validation.
+#
+# Neither GNU grep nor `git grep` (not even with `-P`) handle `\u` as a way to
+# specify UTF-8.
+#
+# To work around that, we use `printf` to produce the pattern as a byte
+# sequence, and then feed that to `git grep` as a byte sequence (setting
+# `LC_CTYPE` to make sure that the arguments are interpreted as intended).
+#
+# Note: we need to use Bash here because its `printf` interprets `\uNNNN` as
+# UTF-8 code points, as desired. Running this script through Ubuntu's `dash`,
+# for example, would use a `printf` that does not understand that syntax.
+
+# U+202a..U+2a2e: LRE, RLE, PDF, LRO and RLO
+# U+2066..U+2069: LRI, RLI, FSI and PDI
+regex='(\u202a|\u202b|\u202c|\u202d|\u202e|\u2066|\u2067|\u2068|\u2069)'
+
+! LC_CTYPE=C git grep -El "$(LC_CTYPE=C.UTF-8 printf "$regex")" \
+	-- ':(exclude,attr:binary)' ':(exclude)*.po'
diff --git a/ci/install-dependencies.sh b/ci/install-dependencies.sh
index 1d0e48f..dbcebad 100755
--- a/ci/install-dependencies.sh
+++ b/ci/install-dependencies.sh
@@ -11,18 +11,11 @@
  tcl tk gettext zlib1g-dev perl-modules liberror-perl libauthen-sasl-perl
  libemail-valid-perl libio-socket-ssl-perl libnet-smtp-ssl-perl"
 
-case "$jobname" in
-linux-clang|linux-gcc|linux-leaks)
-	sudo apt-add-repository -y "ppa:ubuntu-toolchain-r/test"
+case "$runs_on_pool" in
+ubuntu-latest)
 	sudo apt-get -q update
 	sudo apt-get -q -y install language-pack-is libsvn-perl apache2 \
-		$UBUNTU_COMMON_PKGS
-	case "$jobname" in
-	linux-gcc)
-		sudo apt-get -q -y install gcc-8
-		;;
-	esac
-
+		$UBUNTU_COMMON_PKGS $CC_PACKAGE
 	mkdir --parents "$P4_PATH"
 	pushd "$P4_PATH"
 		wget --quiet "$P4WHENCE/bin.linux26x86_64/p4d"
@@ -37,7 +30,7 @@
 		cp git-lfs-$LINUX_GIT_LFS_VERSION/git-lfs .
 	popd
 	;;
-osx-clang|osx-gcc)
+macos-latest)
 	export HOMEBREW_NO_AUTO_UPDATE=1 HOMEBREW_NO_INSTALL_CLEANUP=1
 	# Uncomment this if you want to run perf tests:
 	# brew install gnu-time
@@ -51,15 +44,17 @@
 		brew install --cask --no-quarantine perforce
 	} ||
 	brew install homebrew/cask/perforce
-	case "$jobname" in
-	osx-gcc)
-		brew install gcc@9
-		# Just in case the image is updated to contain gcc@9
-		# pre-installed but not linked.
-		brew link gcc@9
-		;;
-	esac
+
+	if test -n "$CC_PACKAGE"
+	then
+		BREW_PACKAGE=${CC_PACKAGE/-/@}
+		brew install "$BREW_PACKAGE"
+		brew link "$BREW_PACKAGE"
+	fi
 	;;
+esac
+
+case "$jobname" in
 StaticAnalysis)
 	sudo apt-get -q update
 	sudo apt-get -q -y install coccinelle libcurl4-openssl-dev libssl-dev \
@@ -77,7 +72,7 @@
 	test -n "$ALREADY_HAVE_ASCIIDOCTOR" ||
 	sudo gem install --version 1.5.8 asciidoctor
 	;;
-linux-gcc-default|linux-gcc-4.8)
+linux-gcc-default)
 	sudo apt-get -q update
 	sudo apt-get -q -y install $UBUNTU_COMMON_PKGS
 	;;
diff --git a/ci/install-docker-dependencies.sh b/ci/install-docker-dependencies.sh
index 07a8c6b..78b7e32 100755
--- a/ci/install-docker-dependencies.sh
+++ b/ci/install-docker-dependencies.sh
@@ -4,7 +4,7 @@
 #
 
 case "$jobname" in
-Linux32)
+linux32)
 	linux32 --32bit i386 sh -c '
 		apt update >/dev/null &&
 		apt install -y build-essential libcurl4-openssl-dev \
diff --git a/ci/lib.sh b/ci/lib.sh
index 82cb17f..9d28ab5 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -34,7 +34,7 @@
 # successfully before (e.g. because the branch got rebased, changing only
 # the commit messages).
 skip_good_tree () {
-	if test "$TRAVIS_DEBUG_MODE" = true || test true = "$GITHUB_ACTIONS"
+	if test true = "$GITHUB_ACTIONS"
 	then
 		return
 	fi
@@ -60,7 +60,7 @@
 			cat <<-EOF
 			$(tput setaf 2)Skipping build job for commit $CI_COMMIT.$(tput sgr0)
 			This commit's tree has already been built and tested successfully in build job $prev_good_job_number for commit $prev_good_commit.
-			The log of that build job is available at $(url_for_job_id $prev_good_job_id)
+			The log of that build job is available at $SYSTEM_TASKDEFINITIONSURI$SYSTEM_TEAMPROJECT/_build/results?buildId=$prev_good_job_id
 			To force a re-build delete the branch's cache and then hit 'Restart job'.
 			EOF
 		fi
@@ -91,29 +91,7 @@
 # and installing dependencies.
 set -ex
 
-if test true = "$TRAVIS"
-then
-	CI_TYPE=travis
-	# When building a PR, TRAVIS_BRANCH refers to the *target* branch. Not
-	# what we want here. We want the source branch instead.
-	CI_BRANCH="${TRAVIS_PULL_REQUEST_BRANCH:-$TRAVIS_BRANCH}"
-	CI_COMMIT="$TRAVIS_COMMIT"
-	CI_JOB_ID="$TRAVIS_JOB_ID"
-	CI_JOB_NUMBER="$TRAVIS_JOB_NUMBER"
-	CI_OS_NAME="$TRAVIS_OS_NAME"
-	CI_REPO_SLUG="$TRAVIS_REPO_SLUG"
-
-	cache_dir="$HOME/travis-cache"
-
-	url_for_job_id () {
-		echo "https://travis-ci.org/$CI_REPO_SLUG/jobs/$1"
-	}
-
-	BREW_INSTALL_PACKAGES="git-lfs gettext"
-	export GIT_PROVE_OPTS="--timer --jobs 3 --state=failed,slow,save"
-	export GIT_TEST_OPTS="--verbose-log -x --immediate"
-	MAKEFLAGS="$MAKEFLAGS --jobs=2"
-elif test -n "$SYSTEM_COLLECTIONURI" || test -n "$SYSTEM_TASKDEFINITIONSURI"
+if test -n "$SYSTEM_COLLECTIONURI" || test -n "$SYSTEM_TASKDEFINITIONSURI"
 then
 	CI_TYPE=azure-pipelines
 	# We are running in Azure Pipelines
@@ -130,10 +108,6 @@
 	# among *all* phases)
 	cache_dir="$HOME/test-cache/$SYSTEM_PHASENAME"
 
-	url_for_job_id () {
-		echo "$SYSTEM_TASKDEFINITIONSURI$SYSTEM_TEAMPROJECT/_build/results?buildId=$1"
-	}
-
 	export GIT_PROVE_OPTS="--timer --jobs 10 --state=failed,slow,save"
 	export GIT_TEST_OPTS="--verbose-log -x --write-junit-xml"
 	MAKEFLAGS="$MAKEFLAGS --jobs=10"
@@ -182,11 +156,15 @@
 export GIT_TEST_CLONE_2GB=true
 export SKIP_DASHED_BUILT_INS=YesPlease
 
-case "$jobname" in
-linux-clang|linux-gcc|linux-leaks)
+case "$runs_on_pool" in
+ubuntu-latest)
+	if test "$jobname" = "linux-gcc-default"
+	then
+		break
+	fi
+
 	if [ "$jobname" = linux-gcc ]
 	then
-		export CC=gcc-8
 		MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=/usr/bin/python3"
 	else
 		MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=/usr/bin/python2"
@@ -206,24 +184,20 @@
 	GIT_LFS_PATH="$HOME/custom/git-lfs"
 	export PATH="$GIT_LFS_PATH:$P4_PATH:$PATH"
 	;;
-osx-clang|osx-gcc)
+macos-latest)
 	if [ "$jobname" = osx-gcc ]
 	then
-		export CC=gcc-9
 		MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=$(which python3)"
 	else
 		MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=$(which python2)"
 	fi
+	;;
+esac
 
-	# t9810 occasionally fails on Travis CI OS X
-	# t9816 occasionally fails with "TAP out of sequence errors" on
-	# Travis CI OS X
-	export GIT_SKIP_TESTS="t9810 t9816"
-	;;
-linux-gcc-default)
-	;;
-Linux32)
+case "$jobname" in
+linux32)
 	CC=gcc
+	MAKEFLAGS="$MAKEFLAGS NO_UNCOMPRESS2=1"
 	;;
 linux-musl)
 	CC=gcc
@@ -231,9 +205,6 @@
 	MAKEFLAGS="$MAKEFLAGS NO_REGEX=Yes ICONV_OMITS_BOM=Yes"
 	MAKEFLAGS="$MAKEFLAGS GIT_TEST_UTF8_LOCALE=C.UTF-8"
 	;;
-esac
-
-case "$jobname" in
 linux-leaks)
 	export SANITIZE=leak
 	export GIT_TEST_PASSING_SANITIZE_LEAK=true
diff --git a/ci/print-test-failures.sh b/ci/print-test-failures.sh
index c70d6cd..57277ee 100755
--- a/ci/print-test-failures.sh
+++ b/ci/print-test-failures.sh
@@ -39,8 +39,6 @@
 		test_name="${test_name##*/}"
 		trash_dir="trash directory.$test_name"
 		case "$CI_TYPE" in
-		travis)
-			;;
 		azure-pipelines)
 			mkdir -p failed-test-artifacts
 			mv "$trash_dir" failed-test-artifacts
@@ -88,11 +86,3 @@
 		fi
 	fi
 done
-
-if [ $combined_trash_size -gt 0 ]
-then
-	echo "------------------------------------------------------------------------"
-	echo "Trash directories embedded in this log can be extracted by running:"
-	echo
-	echo "  curl https://api.travis-ci.org/v3/job/$TRAVIS_JOB_ID/log.txt |./ci/util/extract-trash-dirs.sh"
-fi
diff --git a/ci/run-build-and-tests.sh b/ci/run-build-and-tests.sh
index cc62616..280dda7 100755
--- a/ci/run-build-and-tests.sh
+++ b/ci/run-build-and-tests.sh
@@ -10,16 +10,13 @@
 *) ln -s "$cache_dir/.prove" t/.prove;;
 esac
 
-if test "$jobname" = "pedantic"
-then
-	export DEVOPTS=pedantic
-fi
+export MAKE_TARGETS="all test"
 
-make
 case "$jobname" in
 linux-gcc)
 	export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-	make test
+	;;
+linux-TEST-vars)
 	export GIT_TEST_SPLIT_INDEX=yes
 	export GIT_TEST_MERGE_ALGORITHM=recursive
 	export GIT_TEST_FULL_IN_PACK_ARRAY=true
@@ -33,23 +30,25 @@
 	export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
 	export GIT_TEST_WRITE_REV_INDEX=1
 	export GIT_TEST_CHECKOUT_WORKERS=2
-	make test
 	;;
 linux-clang)
 	export GIT_TEST_DEFAULT_HASH=sha1
-	make test
+	;;
+linux-sha256)
 	export GIT_TEST_DEFAULT_HASH=sha256
-	make test
 	;;
-linux-gcc-4.8|pedantic)
+pedantic)
 	# Don't run the tests; we only care about whether Git can be
-	# built with GCC 4.8 or with pedantic
-	;;
-*)
-	make test
+	# built.
+	export DEVOPTS=pedantic
+	export MAKE_TARGETS=all
 	;;
 esac
 
+# Any new "test" targets should not go after this "make", but should
+# adjust $MAKE_TARGETS. Otherwise compilation-only targets above will
+# start running tests.
+make $MAKE_TARGETS
 check_unignored_build_artifacts
 
 save_good_tree
diff --git a/ci/run-docker-build.sh b/ci/run-docker-build.sh
index 8d47a5f..6cd832e 100755
--- a/ci/run-docker-build.sh
+++ b/ci/run-docker-build.sh
@@ -15,7 +15,7 @@
 fi
 
 case "$jobname" in
-Linux32)
+linux32)
 	switch_cmd="linux32 --32bit i386"
 	;;
 linux-musl)
@@ -47,15 +47,6 @@
 	else
 		useradd -u $HOST_UID $CI_USER
 	fi
-
-	# Due to a bug the test suite was run as root in the past, so
-	# a prove state file created back then is only accessible by
-	# root.  Now that bug is fixed, the test suite is run as a
-	# regular user, but the prove state file coming from Travis
-	# CI's cache might still be owned by root.
-	# Make sure that this user has rights to any cached files,
-	# including an existing prove state file.
-	test -n "$cache_dir" && chown -R $HOST_UID:$HOST_UID "$cache_dir"
 fi
 
 # Build and test
diff --git a/ci/run-docker.sh b/ci/run-docker.sh
index 37fa372..af89d16 100755
--- a/ci/run-docker.sh
+++ b/ci/run-docker.sh
@@ -6,7 +6,7 @@
 . ${0%/*}/lib.sh
 
 case "$jobname" in
-Linux32)
+linux32)
 	CI_CONTAINER="daald/ubuntu32:xenial"
 	;;
 linux-musl)
@@ -25,7 +25,7 @@
 # root@container:/# export jobname=<jobname>
 # root@container:/# /usr/src/git/ci/run-docker-build.sh <host-user-id>
 
-container_cache_dir=/tmp/travis-cache
+container_cache_dir=/tmp/container-cache
 
 docker run \
 	--interactive \
diff --git a/color.c b/color.c
index 64f52a4..4f884c6 100644
--- a/color.c
+++ b/color.c
@@ -40,7 +40,7 @@
 	enum {
 		COLOR_UNSPECIFIED = 0,
 		COLOR_NORMAL,
-		COLOR_ANSI, /* basic 0-7 ANSI colors */
+		COLOR_ANSI, /* basic 0-7 ANSI colors + "default" (value = 9) */
 		COLOR_256,
 		COLOR_RGB
 	} type;
@@ -83,6 +83,27 @@
 	int i;
 	int color_offset = COLOR_FOREGROUND_ANSI;
 
+	if (match_word(name, len, "default")) {
+		/*
+		 * Restores to the terminal's default color, which may not be
+		 * the same as explicitly setting "white" or "black".
+		 *
+		 * ECMA-48 - Control Functions \
+		 *  for Coded Character Sets, 5th edition (June 1991):
+		 * > 39 default display colour (implementation-defined)
+		 * > 49 default background colour (implementation-defined)
+		 *
+		 * Although not supported /everywhere/--according to terminfo,
+		 * some terminals define "op" (original pair) as a blunt
+		 * "set to white on black", or even "send full SGR reset"--
+		 * it's standard and well-supported enough that if a user
+		 * asks for it in their config this will do the right thing.
+		 */
+		out->type = COLOR_ANSI;
+		out->value = 9 + color_offset;
+		return 0;
+	}
+
 	if (strncasecmp(name, "bright", 6) == 0) {
 		color_offset = COLOR_FOREGROUND_BRIGHT_ANSI;
 		name += 6;
@@ -234,6 +255,7 @@
 	const char *ptr = value;
 	int len = value_len;
 	char *end = dst + COLOR_MAXLEN;
+	unsigned int has_reset = 0;
 	unsigned int attr = 0;
 	struct color fg = { COLOR_UNSPECIFIED };
 	struct color bg = { COLOR_UNSPECIFIED };
@@ -248,12 +270,7 @@
 		return 0;
 	}
 
-	if (!strncasecmp(ptr, "reset", len)) {
-		xsnprintf(dst, end - dst, GIT_COLOR_RESET);
-		return 0;
-	}
-
-	/* [fg [bg]] [attr]... */
+	/* [reset] [fg [bg]] [attr]... */
 	while (len > 0) {
 		const char *word = ptr;
 		struct color c = { COLOR_UNSPECIFIED };
@@ -270,6 +287,11 @@
 			len--;
 		}
 
+		if (match_word(word, wordlen, "reset")) {
+			has_reset = 1;
+			continue;
+		}
+
 		if (!parse_color(&c, word, wordlen)) {
 			if (fg.type == COLOR_UNSPECIFIED) {
 				fg = c;
@@ -295,13 +317,16 @@
 	*dst++ = (x); \
 } while(0)
 
-	if (attr || !color_empty(&fg) || !color_empty(&bg)) {
+	if (has_reset || attr || !color_empty(&fg) || !color_empty(&bg)) {
 		int sep = 0;
 		int i;
 
 		OUT('\033');
 		OUT('[');
 
+		if (has_reset)
+			sep++;
+
 		for (i = 0; attr; i++) {
 			unsigned bit = (1 << i);
 			if (!(attr & bit))
diff --git a/color.h b/color.h
index 98894d6..cfc8f84 100644
--- a/color.h
+++ b/color.h
@@ -6,6 +6,7 @@
 /*
  * The maximum length of ANSI color sequence we would generate:
  * - leading ESC '['            2
+ * - reset ';' .................1
  * - attr + ';'                 2 * num_attr (e.g. "1;")
  * - no-attr + ';'              3 * num_attr (e.g. "22;")
  * - fg color + ';'             17 (e.g. "38;2;255;255;255;")
@@ -24,30 +25,42 @@
 #define GIT_COLOR_NORMAL	""
 #define GIT_COLOR_RESET		"\033[m"
 #define GIT_COLOR_BOLD		"\033[1m"
+#define GIT_COLOR_BLACK		"\033[30m"
 #define GIT_COLOR_RED		"\033[31m"
 #define GIT_COLOR_GREEN		"\033[32m"
 #define GIT_COLOR_YELLOW	"\033[33m"
 #define GIT_COLOR_BLUE		"\033[34m"
 #define GIT_COLOR_MAGENTA	"\033[35m"
 #define GIT_COLOR_CYAN		"\033[36m"
+#define GIT_COLOR_WHITE		"\033[37m"
+#define GIT_COLOR_DEFAULT	"\033[39m"
+#define GIT_COLOR_BOLD_BLACK	"\033[1;30m"
 #define GIT_COLOR_BOLD_RED	"\033[1;31m"
 #define GIT_COLOR_BOLD_GREEN	"\033[1;32m"
 #define GIT_COLOR_BOLD_YELLOW	"\033[1;33m"
 #define GIT_COLOR_BOLD_BLUE	"\033[1;34m"
 #define GIT_COLOR_BOLD_MAGENTA	"\033[1;35m"
 #define GIT_COLOR_BOLD_CYAN	"\033[1;36m"
+#define GIT_COLOR_BOLD_WHITE	"\033[1;37m"
+#define GIT_COLOR_BOLD_DEFAULT	"\033[1;39m"
+#define GIT_COLOR_FAINT_BLACK	"\033[2;30m"
 #define GIT_COLOR_FAINT_RED	"\033[2;31m"
 #define GIT_COLOR_FAINT_GREEN	"\033[2;32m"
 #define GIT_COLOR_FAINT_YELLOW	"\033[2;33m"
 #define GIT_COLOR_FAINT_BLUE	"\033[2;34m"
 #define GIT_COLOR_FAINT_MAGENTA	"\033[2;35m"
 #define GIT_COLOR_FAINT_CYAN	"\033[2;36m"
+#define GIT_COLOR_FAINT_WHITE	"\033[2;37m"
+#define GIT_COLOR_FAINT_DEFAULT	"\033[2;39m"
+#define GIT_COLOR_BG_BLACK	"\033[40m"
 #define GIT_COLOR_BG_RED	"\033[41m"
 #define GIT_COLOR_BG_GREEN	"\033[42m"
 #define GIT_COLOR_BG_YELLOW	"\033[43m"
 #define GIT_COLOR_BG_BLUE	"\033[44m"
 #define GIT_COLOR_BG_MAGENTA	"\033[45m"
 #define GIT_COLOR_BG_CYAN	"\033[46m"
+#define GIT_COLOR_BG_WHITE	"\033[47m"
+#define GIT_COLOR_BG_DEFAULT	"\033[49m"
 #define GIT_COLOR_FAINT		"\033[2m"
 #define GIT_COLOR_FAINT_ITALIC	"\033[2;3m"
 #define GIT_COLOR_REVERSE	"\033[7m"
diff --git a/command-list.txt b/command-list.txt
index eb9cee8..675c28f 100644
--- a/command-list.txt
+++ b/command-list.txt
@@ -43,7 +43,7 @@
 # specified here, which can only have "guide" attribute and nothing
 # else.
 #
-### command list (do not change this line, also do not change alignment)
+### command list (do not change this line)
 # command name                          category [category] [category]
 git-add                                 mainporcelain           worktree
 git-am                                  mainporcelain
@@ -60,9 +60,9 @@
 git-check-attr                          purehelpers
 git-check-ignore                        purehelpers
 git-check-mailmap                       purehelpers
+git-check-ref-format                    purehelpers
 git-checkout                            mainporcelain
 git-checkout-index                      plumbingmanipulators
-git-check-ref-format                    purehelpers
 git-cherry                              plumbinginterrogators          complete
 git-cherry-pick                         mainporcelain
 git-citool                              mainporcelain
@@ -111,7 +111,6 @@
 git-init                                mainporcelain           init
 git-instaweb                            ancillaryinterrogators          complete
 git-interpret-trailers                  purehelpers
-gitk                                    mainporcelain
 git-log                                 mainporcelain           info
 git-ls-files                            plumbinginterrogators
 git-ls-remote                           plumbinginterrogators
@@ -124,11 +123,11 @@
 git-merge-file                          plumbingmanipulators
 git-merge-index                         plumbingmanipulators
 git-merge-one-file                      purehelpers
-git-mergetool                           ancillarymanipulators           complete
 git-merge-tree                          ancillaryinterrogators
-git-multi-pack-index                    plumbingmanipulators
+git-mergetool                           ancillarymanipulators           complete
 git-mktag                               plumbingmanipulators
 git-mktree                              plumbingmanipulators
+git-multi-pack-index                    plumbingmanipulators
 git-mv                                  mainporcelain           worktree
 git-name-rev                            plumbinginterrogators
 git-notes                               mainporcelain
@@ -154,23 +153,23 @@
 git-rerere                              ancillaryinterrogators
 git-reset                               mainporcelain           history
 git-restore                             mainporcelain           worktree
-git-revert                              mainporcelain
 git-rev-list                            plumbinginterrogators
 git-rev-parse                           plumbinginterrogators
+git-revert                              mainporcelain
 git-rm                                  mainporcelain           worktree
 git-send-email                          foreignscminterface             complete
 git-send-pack                           synchingrepositories
+git-sh-i18n                             purehelpers
+git-sh-setup                            purehelpers
 git-shell                               synchelpers
 git-shortlog                            mainporcelain
 git-show                                mainporcelain           info
 git-show-branch                         ancillaryinterrogators          complete
 git-show-index                          plumbinginterrogators
 git-show-ref                            plumbinginterrogators
-git-sh-i18n                             purehelpers
-git-sh-setup                            purehelpers
 git-sparse-checkout                     mainporcelain
-git-stash                               mainporcelain
 git-stage                                                               complete
+git-stash                               mainporcelain
 git-status                              mainporcelain           info
 git-stripspace                          purehelpers
 git-submodule                           mainporcelain
@@ -189,7 +188,6 @@
 git-verify-commit                       ancillaryinterrogators
 git-verify-pack                         plumbinginterrogators
 git-verify-tag                          ancillaryinterrogators
-gitweb                                  ancillaryinterrogators
 git-whatchanged                         ancillaryinterrogators          complete
 git-worktree                            mainporcelain
 git-write-tree                          plumbingmanipulators
@@ -204,6 +202,7 @@
 gitglossary                             guide
 githooks                                guide
 gitignore                               guide
+gitk                                    mainporcelain
 gitmailmap                              guide
 gitmodules                              guide
 gitnamespaces                           guide
@@ -211,6 +210,7 @@
 gitrepository-layout                    guide
 gitrevisions                            guide
 gitsubmodules                           guide
-gittutorial-2                           guide
 gittutorial                             guide
+gittutorial-2                           guide
+gitweb                                  ancillaryinterrogators
 gitworkflows                            guide
diff --git a/commit-graph.c b/commit-graph.c
index 2706683..265c010 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -632,10 +632,13 @@
 	struct object_directory *odb;
 
 	/*
+	 * Early return if there is no git dir or if the commit graph is
+	 * disabled.
+	 *
 	 * This must come before the "already attempted?" check below, because
 	 * we want to disable even an already-loaded graph file.
 	 */
-	if (r->commit_graph_disabled)
+	if (!r->gitdir || r->commit_graph_disabled)
 		return 0;
 
 	if (r->objects->commit_graph_attempted)
diff --git a/commit.c b/commit.c
index 551de49..a348f08 100644
--- a/commit.c
+++ b/commit.c
@@ -1212,8 +1212,10 @@
 
 	if (parse_signed_commit(commit, &payload, &signature, the_hash_algo) <= 0)
 		goto out;
-	ret = check_signature(payload.buf, payload.len, signature.buf,
-		signature.len, sigc);
+
+	sigc->payload_type = SIGNATURE_PAYLOAD_COMMIT;
+	sigc->payload = strbuf_detach(&payload, &sigc->payload_len);
+	ret = check_signature(sigc, signature.buf, signature.len);
 
  out:
 	strbuf_release(&payload);
diff --git a/common-main.c b/common-main.c
index 71e21dd..29fb745 100644
--- a/common-main.c
+++ b/common-main.c
@@ -26,6 +26,7 @@
 int main(int argc, const char **argv)
 {
 	int result;
+	struct strbuf tmp = STRBUF_INIT;
 
 	trace2_initialize_clock();
 
@@ -49,9 +50,15 @@
 	trace2_cmd_start(argv);
 	trace2_collect_process_info(TRACE2_PROCESS_INFO_STARTUP);
 
+	if (!strbuf_getcwd(&tmp))
+		tmp_original_cwd = strbuf_detach(&tmp, NULL);
+
 	result = cmd_main(argc, argv);
 
-	trace2_cmd_exit(result);
-
-	return result;
+	/*
+	 * We define exit() to call trace2_cmd_exit_fl() in
+	 * git-compat-util.h. Whether we reach this or exit()
+	 * elsewhere we'll always run our trace2 exit handler.
+	 */
+	exit(result);
 }
diff --git a/compat/.gitattributes b/compat/.gitattributes
new file mode 100644
index 0000000..40dbfb1
--- /dev/null
+++ b/compat/.gitattributes
@@ -0,0 +1 @@
+/zlib-uncompress2.c	whitespace=-indent-with-non-tab,-trailing-space
diff --git a/compat/mingw.c b/compat/mingw.c
index 9e0cd1e..640dcb1 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -8,6 +8,8 @@
 #include "win32/lazyload.h"
 #include "../config.h"
 #include "dir.h"
+#define SECURITY_WIN32
+#include <sspi.h>
 
 #define HCAST(type, handle) ((type)(intptr_t)handle)
 
@@ -1008,7 +1010,7 @@
 	/* a pointer to the original strftime in case we can't find the UCRT version */
 	static size_t (*fallback)(char *, size_t, const char *, const struct tm *) = strftime;
 	size_t ret;
-	DECLARE_PROC_ADDR(ucrtbase.dll, size_t, strftime, char *, size_t,
+	DECLARE_PROC_ADDR(ucrtbase.dll, size_t, __cdecl, strftime, char *, size_t,
 		const char *, const struct tm *);
 
 	if (INIT_PROC_ADDR(strftime))
@@ -1083,6 +1085,7 @@
 	return 0;
 }
 
+#ifndef __MINGW64__
 struct tm *gmtime_r(const time_t *timep, struct tm *result)
 {
 	if (gmtime_s(result, timep) == 0)
@@ -1096,6 +1099,7 @@
 		return result;
 	return NULL;
 }
+#endif
 
 char *mingw_getcwd(char *pointer, int len)
 {
@@ -2183,7 +2187,7 @@
 
 static char *get_extended_user_info(enum EXTENDED_NAME_FORMAT type)
 {
-	DECLARE_PROC_ADDR(secur32.dll, BOOL, GetUserNameExW,
+	DECLARE_PROC_ADDR(secur32.dll, BOOL, SEC_ENTRY, GetUserNameExW,
 		enum EXTENDED_NAME_FORMAT, LPCWSTR, PULONG);
 	static wchar_t wbuffer[1024];
 	DWORD len;
diff --git a/compat/unsetenv.c b/compat/unsetenv.c
index bf5fd70..b9d34af 100644
--- a/compat/unsetenv.c
+++ b/compat/unsetenv.c
@@ -1,6 +1,6 @@
 #include "../git-compat-util.h"
 
-void gitunsetenv (const char *name)
+int gitunsetenv(const char *name)
 {
 #if !defined(__MINGW32__)
      extern char **environ;
@@ -24,4 +24,6 @@
 	  ++dst;
      }
      environ[dst] = NULL;
+
+     return 0;
 }
diff --git a/compat/win32/lazyload.h b/compat/win32/lazyload.h
index 2b36371..f2bb96c 100644
--- a/compat/win32/lazyload.h
+++ b/compat/win32/lazyload.h
@@ -4,7 +4,7 @@
 /*
  * A pair of macros to simplify loading of DLL functions. Example:
  *
- *   DECLARE_PROC_ADDR(kernel32.dll, BOOL, CreateHardLinkW,
+ *   DECLARE_PROC_ADDR(kernel32.dll, BOOL, WINAPI, CreateHardLinkW,
  *                     LPCWSTR, LPCWSTR, LPSECURITY_ATTRIBUTES);
  *
  *   if (!INIT_PROC_ADDR(CreateHardLinkW))
@@ -25,10 +25,10 @@
 };
 
 /* Declares a function to be loaded dynamically from a DLL. */
-#define DECLARE_PROC_ADDR(dll, rettype, function, ...) \
+#define DECLARE_PROC_ADDR(dll, rettype, convention, function, ...) \
 	static struct proc_addr proc_addr_##function = \
 	{ #dll, #function, NULL, 0 }; \
-	typedef rettype (WINAPI *proc_type_##function)(__VA_ARGS__); \
+	typedef rettype (convention *proc_type_##function)(__VA_ARGS__); \
 	static proc_type_##function function
 
 /*
diff --git a/compat/win32/trace2_win32_process_info.c b/compat/win32/trace2_win32_process_info.c
index 8ccbd1c..a53fd92 100644
--- a/compat/win32/trace2_win32_process_info.c
+++ b/compat/win32/trace2_win32_process_info.c
@@ -143,8 +143,8 @@
  */
 static void get_peak_memory_info(void)
 {
-	DECLARE_PROC_ADDR(psapi.dll, BOOL, GetProcessMemoryInfo, HANDLE,
-			  PPROCESS_MEMORY_COUNTERS, DWORD);
+	DECLARE_PROC_ADDR(psapi.dll, BOOL, WINAPI, GetProcessMemoryInfo,
+			  HANDLE, PPROCESS_MEMORY_COUNTERS, DWORD);
 
 	if (INIT_PROC_ADDR(GetProcessMemoryInfo)) {
 		PROCESS_MEMORY_COUNTERS pmc;
diff --git a/compat/winansi.c b/compat/winansi.c
index c27b20a..4fceecf 100644
--- a/compat/winansi.c
+++ b/compat/winansi.c
@@ -45,8 +45,9 @@
 static void warn_if_raster_font(void)
 {
 	DWORD fontFamily = 0;
-	DECLARE_PROC_ADDR(kernel32.dll, BOOL, GetCurrentConsoleFontEx,
-			HANDLE, BOOL, PCONSOLE_FONT_INFOEX);
+	DECLARE_PROC_ADDR(kernel32.dll, BOOL, WINAPI,
+			GetCurrentConsoleFontEx, HANDLE, BOOL,
+			PCONSOLE_FONT_INFOEX);
 
 	/* don't bother if output was ascii only */
 	if (!non_ascii_used)
diff --git a/compat/zlib-uncompress2.c b/compat/zlib-uncompress2.c
new file mode 100644
index 0000000..722610b
--- /dev/null
+++ b/compat/zlib-uncompress2.c
@@ -0,0 +1,95 @@
+/* taken from zlib's uncompr.c
+
+   commit cacf7f1d4e3d44d871b605da3b647f07d718623f
+   Author: Mark Adler <madler@alumni.caltech.edu>
+   Date:   Sun Jan 15 09:18:46 2017 -0800
+
+       zlib 1.2.11
+
+*/
+
+#include "../reftable/system.h"
+#define z_const
+
+/*
+ * Copyright (C) 1995-2003, 2010, 2014, 2016 Jean-loup Gailly, Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#include <zlib.h>
+
+/* clang-format off */
+
+/* ===========================================================================
+     Decompresses the source buffer into the destination buffer.  *sourceLen is
+   the byte length of the source buffer. Upon entry, *destLen is the total size
+   of the destination buffer, which must be large enough to hold the entire
+   uncompressed data. (The size of the uncompressed data must have been saved
+   previously by the compressor and transmitted to the decompressor by some
+   mechanism outside the scope of this compression library.) Upon exit,
+   *destLen is the size of the decompressed data and *sourceLen is the number
+   of source bytes consumed. Upon return, source + *sourceLen points to the
+   first unused input byte.
+
+     uncompress returns Z_OK if success, Z_MEM_ERROR if there was not enough
+   memory, Z_BUF_ERROR if there was not enough room in the output buffer, or
+   Z_DATA_ERROR if the input data was corrupted, including if the input data is
+   an incomplete zlib stream.
+*/
+int ZEXPORT uncompress2 (
+    Bytef *dest,
+    uLongf *destLen,
+    const Bytef *source,
+    uLong *sourceLen) {
+    z_stream stream;
+    int err;
+    const uInt max = (uInt)-1;
+    uLong len, left;
+    Byte buf[1];    /* for detection of incomplete stream when *destLen == 0 */
+
+    len = *sourceLen;
+    if (*destLen) {
+	left = *destLen;
+	*destLen = 0;
+    }
+    else {
+	left = 1;
+	dest = buf;
+    }
+
+    stream.next_in = (z_const Bytef *)source;
+    stream.avail_in = 0;
+    stream.zalloc = (alloc_func)0;
+    stream.zfree = (free_func)0;
+    stream.opaque = (voidpf)0;
+
+    err = inflateInit(&stream);
+    if (err != Z_OK) return err;
+
+    stream.next_out = dest;
+    stream.avail_out = 0;
+
+    do {
+	if (stream.avail_out == 0) {
+	    stream.avail_out = left > (uLong)max ? max : (uInt)left;
+	    left -= stream.avail_out;
+	}
+	if (stream.avail_in == 0) {
+	    stream.avail_in = len > (uLong)max ? max : (uInt)len;
+	    len -= stream.avail_in;
+	}
+	err = inflate(&stream, Z_NO_FLUSH);
+    } while (err == Z_OK);
+
+    *sourceLen -= len + stream.avail_in;
+    if (dest != buf)
+	*destLen = stream.total_out;
+    else if (stream.total_out && err == Z_BUF_ERROR)
+	left = 1;
+
+    inflateEnd(&stream);
+    return err == Z_STREAM_END ? Z_OK :
+	   err == Z_NEED_DICT ? Z_DATA_ERROR  :
+	   err == Z_BUF_ERROR && left + stream.avail_out ? Z_DATA_ERROR :
+	   err;
+}
diff --git a/config.c b/config.c
index c5873f3..2bffa8d 100644
--- a/config.c
+++ b/config.c
@@ -1559,9 +1559,12 @@
 static int git_default_branch_config(const char *var, const char *value)
 {
 	if (!strcmp(var, "branch.autosetupmerge")) {
-		if (value && !strcasecmp(value, "always")) {
+		if (value && !strcmp(value, "always")) {
 			git_branch_track = BRANCH_TRACK_ALWAYS;
 			return 0;
+		} else if (value && !strcmp(value, "inherit")) {
+			git_branch_track = BRANCH_TRACK_INHERIT;
+			return 0;
 		}
 		git_branch_track = git_config_bool(var, value);
 		return 0;
@@ -2555,11 +2558,12 @@
 {
 	const struct string_list *values;
 	struct key_value_info *kv_info;
+	report_fn error_fn = get_error_routine();
 
 	if (err) {
 		va_list params;
 		va_start(params, err);
-		vreportf("error: ", err, params);
+		error_fn(err, params);
 		va_end(params);
 	}
 	values = git_config_get_value_multi(key);
diff --git a/config.mak.dev b/config.mak.dev
index 7673fed..d4afac6 100644
--- a/config.mak.dev
+++ b/config.mak.dev
@@ -19,6 +19,11 @@
 endif
 endif
 endif
+
+ifneq ($(or $(filter gcc6,$(COMPILER_FEATURES)),$(filter clang7,$(COMPILER_FEATURES))),)
+DEVELOPER_CFLAGS += -std=gnu99
+endif
+
 DEVELOPER_CFLAGS += -Wdeclaration-after-statement
 DEVELOPER_CFLAGS += -Wformat-security
 DEVELOPER_CFLAGS += -Wold-style-definition
diff --git a/config.mak.uname b/config.mak.uname
index 3236a49..9b3e9bf 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -58,7 +58,6 @@
 	# -lrt is needed for clock_gettime on glibc <= 2.16
 	NEEDS_LIBRT = YesPlease
 	HAVE_GETDELIM = YesPlease
-	SANE_TEXT_GREP=-a
 	FREAD_READS_DIRECTORIES = UnfortunatelyYes
 	BASIC_CFLAGS += -DHAVE_SYSINFO
 	PROCFS_EXECUTABLE_PATH = /proc/self/exe
@@ -262,6 +261,10 @@
 	FILENO_IS_A_MACRO = UnfortunatelyYes
 endif
 ifeq ($(uname_S),OpenBSD)
+	# Versions < 7.0 need compatibility layer
+	ifeq ($(shell expr "$(uname_R)" : "[1-6]\."),2)
+		NO_UNCOMPRESS2 = UnfortunatelyYes
+	endif
 	NO_STRCASESTR = YesPlease
 	NO_MEMMEM = YesPlease
 	USE_ST_TIMESPEC = YesPlease
@@ -517,6 +520,7 @@
 	endif
 endif
 ifeq ($(uname_S),Minix)
+	NO_UNCOMPRESS2 = YesPlease
 	NO_IPV6 = YesPlease
 	NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease
 	NO_NSEC = YesPlease
@@ -572,6 +576,7 @@
 	NO_SETENV = YesPlease
 	NO_UNSETENV = YesPlease
 	NO_MKDTEMP = YesPlease
+	NO_UNCOMPRESS2 = YesPlease
 	# Currently libiconv-1.9.1.
 	OLD_ICONV = UnfortunatelyYes
 	NO_REGEX = NeedsStartEnd
diff --git a/configure.ac b/configure.ac
index 031e8d3..d60d494 100644
--- a/configure.ac
+++ b/configure.ac
@@ -507,14 +507,6 @@
 	esac
 fi
 
-if grep -a ascii configure.ac >/dev/null; then
-  AC_MSG_RESULT([Using 'grep -a' for sane_grep])
-  SANE_TEXT_GREP=-a
-else
-  SANE_TEXT_GREP=
-fi
-GIT_CONF_SUBST([SANE_TEXT_GREP])
-
 ## Checks for libraries.
 AC_MSG_NOTICE([CHECKS for libraries])
 #
@@ -672,9 +664,22 @@
 	NO_DEFLATE_BOUND=yes])
 LIBS="$old_LIBS"
 
+AC_DEFUN([ZLIBTEST_UNCOMPRESS2_SRC], [
+AC_LANG_PROGRAM([#include <zlib.h>],
+ [uncompress2(NULL,NULL,NULL,NULL);])])
+AC_MSG_CHECKING([for uncompress2 in -lz])
+old_LIBS="$LIBS"
+LIBS="$LIBS -lz"
+AC_LINK_IFELSE([ZLIBTEST_UNCOMPRESS2_SRC],
+	[AC_MSG_RESULT([yes])],
+	[AC_MSG_RESULT([no])
+	NO_UNCOMPRESS2=yes])
+LIBS="$old_LIBS"
+
 GIT_UNSTASH_FLAGS($ZLIB_PATH)
 
 GIT_CONF_SUBST([NO_DEFLATE_BOUND])
+GIT_CONF_SUBST([NO_UNCOMPRESS2])
 
 #
 # Define NEEDS_SOCKET if linking with libc is not enough (SunOS,
diff --git a/connected.c b/connected.c
index 35bd4a2..ed3025e 100644
--- a/connected.c
+++ b/connected.c
@@ -109,7 +109,8 @@
 			     _("Checking connectivity"));
 
 	rev_list.git_cmd = 1;
-	rev_list.env = opt->env;
+	if (opt->env)
+		strvec_pushv(&rev_list.env_array, opt->env);
 	rev_list.in = -1;
 	rev_list.no_stdout = 1;
 	if (opt->err_fd)
diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt
index fd1399c..5100f56 100644
--- a/contrib/buildsystems/CMakeLists.txt
+++ b/contrib/buildsystems/CMakeLists.txt
@@ -208,7 +208,7 @@
 if(CMAKE_C_COMPILER_ID STREQUAL "MSVC")
 	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG ${CMAKE_BINARY_DIR})
 	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_RELEASE ${CMAKE_BINARY_DIR})
-	add_compile_options(/MP)
+	add_compile_options(/MP /std:c11)
 endif()
 
 #default behaviour
@@ -647,6 +647,12 @@
 list(TRANSFORM libxdiff_SOURCES PREPEND "${CMAKE_SOURCE_DIR}/")
 add_library(xdiff STATIC ${libxdiff_SOURCES})
 
+#reftable
+parse_makefile_for_sources(reftable_SOURCES "REFTABLE_OBJS")
+
+list(TRANSFORM reftable_SOURCES PREPEND "${CMAKE_SOURCE_DIR}/")
+add_library(reftable STATIC ${reftable_SOURCES})
+
 if(WIN32)
 	if(NOT MSVC)#use windres when compiling with gcc and clang
 		add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/git.res
@@ -669,7 +675,7 @@
 #link all required libraries to common-main
 add_library(common-main OBJECT ${CMAKE_SOURCE_DIR}/common-main.c)
 
-target_link_libraries(common-main libgit xdiff ${ZLIB_LIBRARIES})
+target_link_libraries(common-main libgit xdiff reftable ${ZLIB_LIBRARIES})
 if(Intl_FOUND)
 	target_link_libraries(common-main ${Intl_LIBRARIES})
 endif()
@@ -781,7 +787,6 @@
 	string(REPLACE "@@USE_GETTEXT_SCHEME@@" "" content "${content}")
 	string(REPLACE "# @@BROKEN_PATH_FIX@@" "" content "${content}")
 	string(REPLACE "@@PERL@@" "${PERL_PATH}" content "${content}")
-	string(REPLACE "@@SANE_TEXT_GREP@@" "-a" content "${content}")
 	string(REPLACE "@@PAGER_ENV@@" "LESS=FRX LV=-c" content "${content}")
 	file(WRITE ${CMAKE_BINARY_DIR}/${script} ${content})
 endforeach()
@@ -909,11 +914,15 @@
 add_executable(test-fake-ssh ${CMAKE_SOURCE_DIR}/t/helper/test-fake-ssh.c)
 target_link_libraries(test-fake-ssh common-main)
 
+#reftable-tests
+parse_makefile_for_sources(test-reftable_SOURCES "REFTABLE_TEST_OBJS")
+list(TRANSFORM test-reftable_SOURCES PREPEND "${CMAKE_SOURCE_DIR}/")
+
 #test-tool
 parse_makefile_for_sources(test-tool_SOURCES "TEST_BUILTINS_OBJS")
 
 list(TRANSFORM test-tool_SOURCES PREPEND "${CMAKE_SOURCE_DIR}/t/helper/")
-add_executable(test-tool ${CMAKE_SOURCE_DIR}/t/helper/test-tool.c ${test-tool_SOURCES})
+add_executable(test-tool ${CMAKE_SOURCE_DIR}/t/helper/test-tool.c ${test-tool_SOURCES} ${test-reftable_SOURCES})
 target_link_libraries(test-tool common-main)
 
 set_target_properties(test-fake-ssh test-tool
diff --git a/contrib/buildsystems/Generators/Vcxproj.pm b/contrib/buildsystems/Generators/Vcxproj.pm
index d258445..1a25789 100644
--- a/contrib/buildsystems/Generators/Vcxproj.pm
+++ b/contrib/buildsystems/Generators/Vcxproj.pm
@@ -77,7 +77,7 @@
     my $libs_release = "\n    ";
     my $libs_debug = "\n    ";
     if (!$static_library) {
-      $libs_release = join(";", sort(grep /^(?!libgit\.lib|xdiff\/lib\.lib|vcs-svn\/lib\.lib)/, @{$$build_structure{"$prefix${name}_LIBS"}}));
+      $libs_release = join(";", sort(grep /^(?!libgit\.lib|xdiff\/lib\.lib|vcs-svn\/lib\.lib|reftable\/libreftable\.lib)/, @{$$build_structure{"$prefix${name}_LIBS"}}));
       $libs_debug = $libs_release;
       $libs_debug =~ s/zlib\.lib/zlibd\.lib/g;
       $libs_debug =~ s/libexpat\.lib/libexpatd\.lib/g;
@@ -232,6 +232,7 @@
 EOM
     if (!$static_library || $target =~ 'vcs-svn' || $target =~ 'xdiff') {
       my $uuid_libgit = $$build_structure{"LIBS_libgit_GUID"};
+      my $uuid_libreftable = $$build_structure{"LIBS_reftable/libreftable_GUID"};
       my $uuid_xdiff_lib = $$build_structure{"LIBS_xdiff/lib_GUID"};
 
       print F << "EOM";
@@ -241,6 +242,14 @@
       <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
     </ProjectReference>
 EOM
+      if (!($name =~ /xdiff|libreftable/)) {
+        print F << "EOM";
+    <ProjectReference Include="$cdup\\reftable\\libreftable\\libreftable.vcxproj">
+      <Project>$uuid_libreftable</Project>
+      <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
+    </ProjectReference>
+EOM
+      }
       if (!($name =~ 'xdiff')) {
         print F << "EOM";
     <ProjectReference Include="$cdup\\xdiff\\lib\\xdiff_lib.vcxproj">
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 7c3a753..377d6c5 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -1566,7 +1566,7 @@
 
 	case "$cur" in
 	--conflict=*)
-		__gitcomp "diff3 merge" "" "${cur##--conflict=}"
+		__gitcomp "diff3 merge zdiff3" "" "${cur##--conflict=}"
 		;;
 	--*)
 		__gitcomp_builtin checkout
@@ -2001,7 +2001,7 @@
 "
 
 __git_log_pretty_formats="oneline short medium full fuller reference email raw format: tformat: mboxrd"
-__git_log_date_formats="relative iso8601 iso8601-strict rfc2822 short local default raw unix format:"
+__git_log_date_formats="relative iso8601 iso8601-strict rfc2822 short local default human raw unix auto: format:"
 
 _git_log ()
 {
@@ -2359,16 +2359,7 @@
 		return
 		;;
 	--*)
-		__gitcomp_builtin send-email "--annotate --bcc --cc --cc-cmd --chain-reply-to
-			--compose --confirm= --dry-run --envelope-sender
-			--from --identity
-			--in-reply-to --no-chain-reply-to --no-signed-off-by-cc
-			--no-suppress-from --no-thread --quiet --reply-to
-			--signed-off-by-cc --smtp-pass --smtp-server
-			--smtp-server-port --smtp-encryption= --smtp-user
-			--subject --suppress-cc= --suppress-from --thread --to
-			--validate --no-validate
-			$__git_format_patch_extra_options"
+		__gitcomp_builtin send-email "$__git_format_patch_extra_options"
 		return
 		;;
 	esac
@@ -2446,7 +2437,7 @@
 
 	case "$cur" in
 	--conflict=*)
-		__gitcomp "diff3 merge" "" "${cur##--conflict=}"
+		__gitcomp "diff3 merge zdiff3" "" "${cur##--conflict=}"
 		;;
 	--*)
 		__gitcomp_builtin switch
@@ -2886,7 +2877,7 @@
 
 	case "$cur" in
 	--conflict=*)
-		__gitcomp "diff3 merge" "" "${cur##--conflict=}"
+		__gitcomp "diff3 merge zdiff3" "" "${cur##--conflict=}"
 		;;
 	--source=*)
 		__git_complete_refs --cur="${cur##--source=}"
diff --git a/contrib/git-jump/README b/contrib/git-jump/README
index 2f618a7..8bcace2 100644
--- a/contrib/git-jump/README
+++ b/contrib/git-jump/README
@@ -65,6 +65,9 @@
 # jump to merge conflicts
 git jump merge
 
+# documentation conflicts are hard; skip past them for now
+git jump merge :^Documentation
+
 # jump to all instances of foo_bar
 git jump grep foo_bar
 
diff --git a/contrib/git-jump/git-jump b/contrib/git-jump/git-jump
index 931b0fe..92dbd4c 100755
--- a/contrib/git-jump/git-jump
+++ b/contrib/git-jump/git-jump
@@ -39,7 +39,7 @@
 }
 
 mode_merge() {
-	git ls-files -u |
+	git ls-files -u "$@" |
 	perl -pe 's/^.*?\t//' |
 	sort -u |
 	while IFS= read fn; do
diff --git a/contrib/mw-to-git/t/t9365-continuing-queries.sh b/contrib/mw-to-git/t/t9365-continuing-queries.sh
index 0164547..d3e7312 100755
--- a/contrib/mw-to-git/t/t9365-continuing-queries.sh
+++ b/contrib/mw-to-git/t/t9365-continuing-queries.sh
@@ -12,7 +12,7 @@
 	for i in $(test_seq 501)
 	do
 		echo "creating revision $i" &&
-		wiki_editpage foo "revision $i<br/>" true
+		wiki_editpage foo "revision $i<br/>" true || return 1
 	done
 '
 
diff --git a/contrib/scalar/.gitignore b/contrib/scalar/.gitignore
new file mode 100644
index 0000000..ff3d47e
--- /dev/null
+++ b/contrib/scalar/.gitignore
@@ -0,0 +1,2 @@
+/*.exe
+/scalar
diff --git a/contrib/scalar/Makefile b/contrib/scalar/Makefile
new file mode 100644
index 0000000..231b1ee
--- /dev/null
+++ b/contrib/scalar/Makefile
@@ -0,0 +1,45 @@
+QUIET_SUBDIR0  = +$(MAKE) -C # space to separate -C and subdir
+QUIET_SUBDIR1  =
+
+ifneq ($(findstring s,$(MAKEFLAGS)),s)
+ifndef V
+	QUIET_GEN      = @echo '   ' GEN $@;
+	QUIET_SUBDIR0  = +@subdir=
+	QUIET_SUBDIR1  = ;$(NO_SUBDIR) echo '   ' SUBDIR $$subdir; \
+			 $(MAKE) $(PRINT_DIR) -C $$subdir
+else
+	export V
+endif
+endif
+
+all:
+
+include ../../config.mak.uname
+-include ../../config.mak.autogen
+-include ../../config.mak
+
+TARGETS = scalar$(X) scalar.o
+GITLIBS = ../../common-main.o ../../libgit.a ../../xdiff/lib.a
+
+all: scalar$(X) ../../bin-wrappers/scalar
+
+$(GITLIBS):
+	$(QUIET_SUBDIR0)../.. $(QUIET_SUBDIR1) $(subst ../../,,$@)
+
+$(TARGETS): $(GITLIBS) scalar.c
+	$(QUIET_SUBDIR0)../.. $(QUIET_SUBDIR1) $(patsubst %,contrib/scalar/%,$@)
+
+clean:
+	$(RM) $(TARGETS) ../../bin-wrappers/scalar
+
+../../bin-wrappers/scalar: ../../wrap-for-bin.sh Makefile
+	@mkdir -p ../../bin-wrappers
+	$(QUIET_GEN)sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
+	     -e 's|@@BUILD_DIR@@|$(shell cd ../.. && pwd)|' \
+	     -e 's|@@PROG@@|contrib/scalar/scalar$(X)|' < $< > $@ && \
+	chmod +x $@
+
+test: all
+	$(MAKE) -C t
+
+.PHONY: $(GITLIBS) all clean test FORCE
diff --git a/contrib/scalar/README.md b/contrib/scalar/README.md
new file mode 100644
index 0000000..634b577
--- /dev/null
+++ b/contrib/scalar/README.md
@@ -0,0 +1,82 @@
+# Scalar - an opinionated repository management tool
+
+Scalar is an add-on to Git that helps users take advantage of advanced
+performance features in Git. Originally implemented in C# using .NET Core,
+based on the learnings from the VFS for Git project, most of the techniques
+developed by the Scalar project have been integrated into core Git already:
+
+* partial clone,
+* commit graphs,
+* multi-pack index,
+* sparse checkout (cone mode),
+* scheduled background maintenance,
+* etc
+
+This directory contains the remaining parts of Scalar that are not (yet) in
+core Git.
+
+## Roadmap
+
+The idea is to populate this directory via incremental patch series and
+eventually move to a top-level directory next to `gitk-git/` and to `git-gui/`. The
+current plan involves the following patch series:
+
+- `scalar-the-beginning`: The initial patch series which sets up
+  `contrib/scalar/` and populates it with a minimal `scalar` command that
+  demonstrates the fundamental ideas.
+
+- `scalar-c-and-C`: The `scalar` command learns about two options that can be
+  specified before the command, `-c <key>=<value>` and `-C <directory>`.
+
+- `scalar-diagnose`: The `scalar` command is taught the `diagnose` subcommand.
+
+- `scalar-and-builtin-fsmonitor`: The built-in FSMonitor is enabled in `scalar
+  register` and in `scalar clone`, for an enormous performance boost when
+  working in large worktrees. This patch series necessarily depends on Jeff
+  Hostetler's FSMonitor patch series to be integrated into Git.
+
+- `scalar-gentler-config-locking`: Scalar enlistments are registered in the
+  user's Git config. This usually does not represent any problem because it is
+  rare for a user to register an enlistment. However, in Scalar's functional
+  tests, Scalar enlistments are created galore, and in parallel, which can lead
+  to lock contention. This patch series works around that problem by re-trying
+  to lock the config file in a gentle fashion.
+
+- `scalar-extra-docs`: Add some extensive documentation that has been written
+  in the original Scalar project (all subject to discussion, of course).
+
+- `optionally-install-scalar`: Now that Scalar is feature (and documentation)
+  complete and is verified in CI builds, let's offer to install it.
+
+- `move-scalar-to-toplevel`: Now that Scalar is complete, let's move it next to
+  `gitk-git/` and to `git-gui/`, making it a top-level command.
+
+The following two patch series exist in Microsoft's fork of Git and are
+publicly available. There is no current plan to upstream them, not because I
+want to withhold these patches, but because I don't think the Git community is
+interested in these patches.
+
+There are some interesting ideas there, but the implementation is too specific
+to Azure Repos and/or VFS for Git to be of much help in general (and also: my
+colleagues tried to upstream some patches already and the enthusiasm for
+integrating things related to Azure Repos and VFS for Git can be summarized in
+very, very few words).
+
+These still exist mainly because the GVFS protocol is what Azure Repos has
+instead of partial clone, while Git is focused on improving partial clone:
+
+- `scalar-with-gvfs`: The primary purpose of this patch series is to support
+  existing Scalar users whose repositories are hosted in Azure Repos (which
+  does not support Git's partial clones, but supports its predecessor, the GVFS
+  protocol, which is used by Scalar to emulate the partial clone).
+
+  Since the GVFS protocol will never be supported by core Git, this patch
+  series will remain in Microsoft's fork of Git.
+
+- `run-scalar-functional-tests`: The Scalar project developed a quite
+  comprehensive set of integration tests (or, "Functional Tests"). They are the
+  sole remaining part of the original C#-based Scalar project, and this patch
+  adds a GitHub workflow that runs them all.
+
+  Since the tests partially depend on features that are only provided in the
+  `scalar-with-gvfs` patch series, this patch cannot be upstreamed.
diff --git a/contrib/scalar/scalar.c b/contrib/scalar/scalar.c
new file mode 100644
index 0000000..1ce9c2b
--- /dev/null
+++ b/contrib/scalar/scalar.c
@@ -0,0 +1,826 @@
+/*
+ * The Scalar command-line interface.
+ */
+
+#include "cache.h"
+#include "gettext.h"
+#include "parse-options.h"
+#include "config.h"
+#include "run-command.h"
+#include "refs.h"
+#include "dir.h"
+#include "packfile.h"
+#include "help.h"
+
+/*
+ * Remove the deepest subdirectory in the provided path string. Path must not
+ * include a trailing path separator. Returns 1 if parent directory found,
+ * otherwise 0.
+ */
+static int strbuf_parent_directory(struct strbuf *buf)
+{
+	size_t len = buf->len;
+	size_t offset = offset_1st_component(buf->buf);
+	char *path_sep = find_last_dir_sep(buf->buf + offset);
+	strbuf_setlen(buf, path_sep ? path_sep - buf->buf : offset);
+
+	return buf->len < len;
+}
+
+static void setup_enlistment_directory(int argc, const char **argv,
+				       const char * const *usagestr,
+				       const struct option *options,
+				       struct strbuf *enlistment_root)
+{
+	struct strbuf path = STRBUF_INIT;
+	char *root;
+	int enlistment_found = 0;
+
+	if (startup_info->have_repository)
+		BUG("gitdir already set up?!?");
+
+	if (argc > 1)
+		usage_with_options(usagestr, options);
+
+	/* find the worktree, determine its corresponding root */
+	if (argc == 1)
+		strbuf_add_absolute_path(&path, argv[0]);
+	else if (strbuf_getcwd(&path) < 0)
+		die(_("need a working directory"));
+
+	strbuf_trim_trailing_dir_sep(&path);
+	do {
+		const size_t len = path.len;
+
+		/* check if currently in enlistment root with src/ workdir */
+		strbuf_addstr(&path, "/src");
+		if (is_nonbare_repository_dir(&path)) {
+			if (enlistment_root)
+				strbuf_add(enlistment_root, path.buf, len);
+
+			enlistment_found = 1;
+			break;
+		}
+
+		/* reset to original path */
+		strbuf_setlen(&path, len);
+
+		/* check if currently in workdir */
+		if (is_nonbare_repository_dir(&path)) {
+			if (enlistment_root) {
+				/*
+				 * If the worktree's directory's name is `src`, the enlistment is the
+				 * parent directory, otherwise it is identical to the worktree.
+				 */
+				root = strip_path_suffix(path.buf, "src");
+				strbuf_addstr(enlistment_root, root ? root : path.buf);
+				free(root);
+			}
+
+			enlistment_found = 1;
+			break;
+		}
+	} while (strbuf_parent_directory(&path));
+
+	if (!enlistment_found)
+		die(_("could not find enlistment root"));
+
+	if (chdir(path.buf) < 0)
+		die_errno(_("could not switch to '%s'"), path.buf);
+
+	strbuf_release(&path);
+	setup_git_directory();
+}
+
+static int run_git(const char *arg, ...)
+{
+	struct strvec argv = STRVEC_INIT;
+	va_list args;
+	const char *p;
+	int res;
+
+	va_start(args, arg);
+	strvec_push(&argv, arg);
+	while ((p = va_arg(args, const char *)))
+		strvec_push(&argv, p);
+	va_end(args);
+
+	res = run_command_v_opt(argv.v, RUN_GIT_CMD);
+
+	strvec_clear(&argv);
+	return res;
+}
+
+static int set_recommended_config(int reconfigure)
+{
+	struct {
+		const char *key;
+		const char *value;
+		int overwrite_on_reconfigure;
+	} config[] = {
+		/* Required */
+		{ "am.keepCR", "true", 1 },
+		{ "core.FSCache", "true", 1 },
+		{ "core.multiPackIndex", "true", 1 },
+		{ "core.preloadIndex", "true", 1 },
+#ifndef WIN32
+		{ "core.untrackedCache", "true", 1 },
+#else
+		/*
+		 * Unfortunately, Scalar's Functional Tests demonstrated
+		 * that the untracked cache feature is unreliable on Windows
+		 * (which is a bummer because that platform would benefit the
+		 * most from it). For some reason, freshly created files seem
+		 * not to update the directory's `lastModified` time
+		 * immediately, but the untracked cache would need to rely on
+		 * that.
+		 *
+		 * Therefore, with a sad heart, we disable this very useful
+		 * feature on Windows.
+		 */
+		{ "core.untrackedCache", "false", 1 },
+#endif
+		{ "core.logAllRefUpdates", "true", 1 },
+		{ "credential.https://dev.azure.com.useHttpPath", "true", 1 },
+		{ "credential.validate", "false", 1 }, /* GCM4W-only */
+		{ "gc.auto", "0", 1 },
+		{ "gui.GCWarning", "false", 1 },
+		{ "index.threads", "true", 1 },
+		{ "index.version", "4", 1 },
+		{ "merge.stat", "false", 1 },
+		{ "merge.renames", "true", 1 },
+		{ "pack.useBitmaps", "false", 1 },
+		{ "pack.useSparse", "true", 1 },
+		{ "receive.autoGC", "false", 1 },
+		{ "reset.quiet", "true", 1 },
+		{ "feature.manyFiles", "false", 1 },
+		{ "feature.experimental", "false", 1 },
+		{ "fetch.unpackLimit", "1", 1 },
+		{ "fetch.writeCommitGraph", "false", 1 },
+#ifdef WIN32
+		{ "http.sslBackend", "schannel", 1 },
+#endif
+		/* Optional */
+		{ "status.aheadBehind", "false" },
+		{ "commitGraph.generationVersion", "1" },
+		{ "core.autoCRLF", "false" },
+		{ "core.safeCRLF", "false" },
+		{ "fetch.showForcedUpdates", "false" },
+		{ NULL, NULL },
+	};
+	int i;
+	char *value;
+
+	for (i = 0; config[i].key; i++) {
+		if ((reconfigure && config[i].overwrite_on_reconfigure) ||
+		    git_config_get_string(config[i].key, &value)) {
+			trace2_data_string("scalar", the_repository, config[i].key, "created");
+			if (git_config_set_gently(config[i].key,
+						  config[i].value) < 0)
+				return error(_("could not configure %s=%s"),
+					     config[i].key, config[i].value);
+		} else {
+			trace2_data_string("scalar", the_repository, config[i].key, "exists");
+			free(value);
+		}
+	}
+
+	/*
+	 * The `log.excludeDecoration` setting is special because it allows
+	 * for multiple values.
+	 */
+	if (git_config_get_string("log.excludeDecoration", &value)) {
+		trace2_data_string("scalar", the_repository,
+				   "log.excludeDecoration", "created");
+		if (git_config_set_multivar_gently("log.excludeDecoration",
+						   "refs/prefetch/*",
+						   CONFIG_REGEX_NONE, 0))
+			return error(_("could not configure "
+				       "log.excludeDecoration"));
+	} else {
+		trace2_data_string("scalar", the_repository,
+				   "log.excludeDecoration", "exists");
+		free(value);
+	}
+
+	return 0;
+}
+
+static int toggle_maintenance(int enable)
+{
+	return run_git("maintenance", enable ? "start" : "unregister", NULL);
+}
+
+static int add_or_remove_enlistment(int add)
+{
+	int res;
+
+	if (!the_repository->worktree)
+		die(_("Scalar enlistments require a worktree"));
+
+	res = run_git("config", "--global", "--get", "--fixed-value",
+		      "scalar.repo", the_repository->worktree, NULL);
+
+	/*
+	 * If we want to add and the setting is already there, then do nothing.
+	 * If we want to remove and the setting is not there, then do nothing.
+	 */
+	if ((add && !res) || (!add && res))
+		return 0;
+
+	return run_git("config", "--global", add ? "--add" : "--unset",
+		       add ? "--no-fixed-value" : "--fixed-value",
+		       "scalar.repo", the_repository->worktree, NULL);
+}
+
+static int register_dir(void)
+{
+	int res = add_or_remove_enlistment(1);
+
+	if (!res)
+		res = set_recommended_config(0);
+
+	if (!res)
+		res = toggle_maintenance(1);
+
+	return res;
+}
+
+static int unregister_dir(void)
+{
+	int res = 0;
+
+	if (toggle_maintenance(0) < 0)
+		res = -1;
+
+	if (add_or_remove_enlistment(0) < 0)
+		res = -1;
+
+	return res;
+}
+
+/* printf-style interface, expects `<key>=<value>` argument */
+static int set_config(const char *fmt, ...)
+{
+	struct strbuf buf = STRBUF_INIT;
+	char *value;
+	int res;
+	va_list args;
+
+	va_start(args, fmt);
+	strbuf_vaddf(&buf, fmt, args);
+	va_end(args);
+
+	value = strchr(buf.buf, '=');
+	if (value)
+		*(value++) = '\0';
+	res = git_config_set_gently(buf.buf, value);
+	strbuf_release(&buf);
+
+	return res;
+}
+
+static char *remote_default_branch(const char *url)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct strbuf out = STRBUF_INIT;
+
+	cp.git_cmd = 1;
+	strvec_pushl(&cp.args, "ls-remote", "--symref", url, "HEAD", NULL);
+	if (!pipe_command(&cp, NULL, 0, &out, 0, NULL, 0)) {
+		const char *line = out.buf;
+
+		while (*line) {
+			const char *eol = strchrnul(line, '\n'), *p;
+			size_t len = eol - line;
+			char *branch;
+
+			if (!skip_prefix(line, "ref: ", &p) ||
+			    !strip_suffix_mem(line, &len, "\tHEAD")) {
+				line = eol + (*eol == '\n');
+				continue;
+			}
+
+			eol = line + len;
+			if (skip_prefix(p, "refs/heads/", &p)) {
+				branch = xstrndup(p, eol - p);
+				strbuf_release(&out);
+				return branch;
+			}
+
+			error(_("remote HEAD is not a branch: '%.*s'"),
+			      (int)(eol - p), p);
+			strbuf_release(&out);
+			return NULL;
+		}
+	}
+	warning(_("failed to get default branch name from remote; "
+		  "using local default"));
+	strbuf_reset(&out);
+
+	child_process_init(&cp);
+	cp.git_cmd = 1;
+	strvec_pushl(&cp.args, "symbolic-ref", "--short", "HEAD", NULL);
+	if (!pipe_command(&cp, NULL, 0, &out, 0, NULL, 0)) {
+		strbuf_trim(&out);
+		return strbuf_detach(&out, NULL);
+	}
+
+	strbuf_release(&out);
+	error(_("failed to get default branch name"));
+	return NULL;
+}
+
+static int delete_enlistment(struct strbuf *enlistment)
+{
+#ifdef WIN32
+	struct strbuf parent = STRBUF_INIT;
+#endif
+
+	if (unregister_dir())
+		die(_("failed to unregister repository"));
+
+#ifdef WIN32
+	/*
+	 * Change the current directory to one outside of the enlistment so
+	 * that we may delete everything underneath it.
+	 */
+	strbuf_addbuf(&parent, enlistment);
+	strbuf_parent_directory(&parent);
+	if (chdir(parent.buf) < 0)
+		die_errno(_("could not switch to '%s'"), parent.buf);
+	strbuf_release(&parent);
+#endif
+
+	if (remove_dir_recursively(enlistment, 0))
+		die(_("failed to delete enlistment directory"));
+
+	return 0;
+}
+
+/*
+ * Dummy implementation; Using `get_version_info()` would cause a link error
+ * without this.
+ */
+void load_builtin_commands(const char *prefix, struct cmdnames *cmds)
+{
+	die("not implemented");
+}
+
+static int cmd_clone(int argc, const char **argv)
+{
+	const char *branch = NULL;
+	int full_clone = 0, single_branch = 0;
+	struct option clone_options[] = {
+		OPT_STRING('b', "branch", &branch, N_("<branch>"),
+			   N_("branch to checkout after clone")),
+		OPT_BOOL(0, "full-clone", &full_clone,
+			 N_("when cloning, create full working directory")),
+		OPT_BOOL(0, "single-branch", &single_branch,
+			 N_("only download metadata for the branch that will "
+			    "be checked out")),
+		OPT_END(),
+	};
+	const char * const clone_usage[] = {
+		N_("scalar clone [<options>] [--] <repo> [<dir>]"),
+		NULL
+	};
+	const char *url;
+	char *enlistment = NULL, *dir = NULL;
+	struct strbuf buf = STRBUF_INIT;
+	int res;
+
+	argc = parse_options(argc, argv, NULL, clone_options, clone_usage, 0);
+
+	if (argc == 2) {
+		url = argv[0];
+		enlistment = xstrdup(argv[1]);
+	} else if (argc == 1) {
+		url = argv[0];
+
+		strbuf_addstr(&buf, url);
+		/* Strip trailing slashes, if any */
+		while (buf.len > 0 && is_dir_sep(buf.buf[buf.len - 1]))
+			strbuf_setlen(&buf, buf.len - 1);
+		/* Strip suffix `.git`, if any */
+		strbuf_strip_suffix(&buf, ".git");
+
+		enlistment = find_last_dir_sep(buf.buf);
+		if (!enlistment) {
+			die(_("cannot deduce worktree name from '%s'"), url);
+		}
+		enlistment = xstrdup(enlistment + 1);
+	} else {
+		usage_msg_opt(_("You must specify a repository to clone."),
+			      clone_usage, clone_options);
+	}
+
+	if (is_directory(enlistment))
+		die(_("directory '%s' exists already"), enlistment);
+
+	dir = xstrfmt("%s/src", enlistment);
+
+	strbuf_reset(&buf);
+	if (branch)
+		strbuf_addf(&buf, "init.defaultBranch=%s", branch);
+	else {
+		char *b = repo_default_branch_name(the_repository, 1);
+		strbuf_addf(&buf, "init.defaultBranch=%s", b);
+		free(b);
+	}
+
+	if ((res = run_git("-c", buf.buf, "init", "--", dir, NULL)))
+		goto cleanup;
+
+	if (chdir(dir) < 0) {
+		res = error_errno(_("could not switch to '%s'"), dir);
+		goto cleanup;
+	}
+
+	setup_git_directory();
+
+	/* common-main already logs `argv` */
+	trace2_def_repo(the_repository);
+
+	if (!branch && !(branch = remote_default_branch(url))) {
+		res = error(_("failed to get default branch for '%s'"), url);
+		goto cleanup;
+	}
+
+	if (set_config("remote.origin.url=%s", url) ||
+	    set_config("remote.origin.fetch="
+		       "+refs/heads/%s:refs/remotes/origin/%s",
+		       single_branch ? branch : "*",
+		       single_branch ? branch : "*") ||
+	    set_config("remote.origin.promisor=true") ||
+	    set_config("remote.origin.partialCloneFilter=blob:none")) {
+		res = error(_("could not configure remote in '%s'"), dir);
+		goto cleanup;
+	}
+
+	if (!full_clone &&
+	    (res = run_git("sparse-checkout", "init", "--cone", NULL)))
+		goto cleanup;
+
+	if (set_recommended_config(0))
+		return error(_("could not configure '%s'"), dir);
+
+	if ((res = run_git("fetch", "--quiet", "origin", NULL))) {
+		warning(_("partial clone failed; attempting full clone"));
+
+		if (set_config("remote.origin.promisor") ||
+		    set_config("remote.origin.partialCloneFilter")) {
+			res = error(_("could not configure for full clone"));
+			goto cleanup;
+		}
+
+		if ((res = run_git("fetch", "--quiet", "origin", NULL)))
+			goto cleanup;
+	}
+
+	if ((res = set_config("branch.%s.remote=origin", branch)))
+		goto cleanup;
+	if ((res = set_config("branch.%s.merge=refs/heads/%s",
+			      branch, branch)))
+		goto cleanup;
+
+	strbuf_reset(&buf);
+	strbuf_addf(&buf, "origin/%s", branch);
+	res = run_git("checkout", "-f", "-t", buf.buf, NULL);
+	if (res)
+		goto cleanup;
+
+	res = register_dir();
+
+cleanup:
+	free(enlistment);
+	free(dir);
+	strbuf_release(&buf);
+	return res;
+}
+
+static int cmd_list(int argc, const char **argv)
+{
+	if (argc != 1)
+		die(_("`scalar list` does not take arguments"));
+
+	if (run_git("config", "--global", "--get-all", "scalar.repo", NULL) < 0)
+		return -1;
+	return 0;
+}
+
+static int cmd_register(int argc, const char **argv)
+{
+	struct option options[] = {
+		OPT_END(),
+	};
+	const char * const usage[] = {
+		N_("scalar register [<enlistment>]"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, NULL, options,
+			     usage, 0);
+
+	setup_enlistment_directory(argc, argv, usage, options, NULL);
+
+	return register_dir();
+}
+
+static int get_scalar_repos(const char *key, const char *value, void *data)
+{
+	struct string_list *list = data;
+
+	if (!strcmp(key, "scalar.repo"))
+		string_list_append(list, value);
+
+	return 0;
+}
+
+static int cmd_reconfigure(int argc, const char **argv)
+{
+	int all = 0;
+	struct option options[] = {
+		OPT_BOOL('a', "all", &all,
+			 N_("reconfigure all registered enlistments")),
+		OPT_END(),
+	};
+	const char * const usage[] = {
+		N_("scalar reconfigure [--all | <enlistment>]"),
+		NULL
+	};
+	struct string_list scalar_repos = STRING_LIST_INIT_DUP;
+	int i, res = 0;
+	struct repository r = { NULL };
+	struct strbuf commondir = STRBUF_INIT, gitdir = STRBUF_INIT;
+
+	argc = parse_options(argc, argv, NULL, options,
+			     usage, 0);
+
+	if (!all) {
+		setup_enlistment_directory(argc, argv, usage, options, NULL);
+
+		return set_recommended_config(1);
+	}
+
+	if (argc > 0)
+		usage_msg_opt(_("--all or <enlistment>, but not both"),
+			      usage, options);
+
+	git_config(get_scalar_repos, &scalar_repos);
+
+	for (i = 0; i < scalar_repos.nr; i++) {
+		const char *dir = scalar_repos.items[i].string;
+
+		strbuf_reset(&commondir);
+		strbuf_reset(&gitdir);
+
+		if (chdir(dir) < 0) {
+			warning_errno(_("could not switch to '%s'"), dir);
+			res = -1;
+		} else if (discover_git_directory(&commondir, &gitdir) < 0) {
+			warning_errno(_("git repository gone in '%s'"), dir);
+			res = -1;
+		} else {
+			git_config_clear();
+
+			the_repository = &r;
+			r.commondir = commondir.buf;
+			r.gitdir = gitdir.buf;
+
+			if (set_recommended_config(1) < 0)
+				res = -1;
+		}
+	}
+
+	string_list_clear(&scalar_repos, 1);
+	strbuf_release(&commondir);
+	strbuf_release(&gitdir);
+
+	return res;
+}
+
+static int cmd_run(int argc, const char **argv)
+{
+	struct option options[] = {
+		OPT_END(),
+	};
+	struct {
+		const char *arg, *task;
+	} tasks[] = {
+		{ "config", NULL },
+		{ "commit-graph", "commit-graph" },
+		{ "fetch", "prefetch" },
+		{ "loose-objects", "loose-objects" },
+		{ "pack-files", "incremental-repack" },
+		{ NULL, NULL }
+	};
+	struct strbuf buf = STRBUF_INIT;
+	const char *usagestr[] = { NULL, NULL };
+	int i;
+
+	strbuf_addstr(&buf, N_("scalar run <task> [<enlistment>]\nTasks:\n"));
+	for (i = 0; tasks[i].arg; i++)
+		strbuf_addf(&buf, "\t%s\n", tasks[i].arg);
+	usagestr[0] = buf.buf;
+
+	argc = parse_options(argc, argv, NULL, options,
+			     usagestr, 0);
+
+	if (!argc)
+		usage_with_options(usagestr, options);
+
+	if (!strcmp("all", argv[0])) {
+		i = -1;
+	} else {
+		for (i = 0; tasks[i].arg && strcmp(tasks[i].arg, argv[0]); i++)
+			; /* keep looking for the task */
+
+		if (i > 0 && !tasks[i].arg) {
+			error(_("no such task: '%s'"), argv[0]);
+			usage_with_options(usagestr, options);
+		}
+	}
+
+	argc--;
+	argv++;
+	setup_enlistment_directory(argc, argv, usagestr, options, NULL);
+	strbuf_release(&buf);
+
+	if (i == 0)
+		return register_dir();
+
+	if (i > 0)
+		return run_git("maintenance", "run",
+			       "--task", tasks[i].task, NULL);
+
+	if (register_dir())
+		return -1;
+	for (i = 1; tasks[i].arg; i++)
+		if (run_git("maintenance", "run",
+			    "--task", tasks[i].task, NULL))
+			return -1;
+	return 0;
+}
+
+static int remove_deleted_enlistment(struct strbuf *path)
+{
+	int res = 0;
+	strbuf_realpath_forgiving(path, path->buf, 1);
+
+	if (run_git("config", "--global",
+		    "--unset", "--fixed-value",
+		    "scalar.repo", path->buf, NULL) < 0)
+		res = -1;
+
+	if (run_git("config", "--global",
+		    "--unset", "--fixed-value",
+		    "maintenance.repo", path->buf, NULL) < 0)
+		res = -1;
+
+	return res;
+}
+
+static int cmd_unregister(int argc, const char **argv)
+{
+	struct option options[] = {
+		OPT_END(),
+	};
+	const char * const usage[] = {
+		N_("scalar unregister [<enlistment>]"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, NULL, options,
+			     usage, 0);
+
+	/*
+	 * Be forgiving when the enlistment or worktree does not even exist any
+	 * longer; This can be the case if a user deleted the worktree by
+	 * mistake and _still_ wants to unregister the thing.
+	 */
+	if (argc == 1) {
+		struct strbuf src_path = STRBUF_INIT, workdir_path = STRBUF_INIT;
+
+		strbuf_addf(&src_path, "%s/src/.git", argv[0]);
+		strbuf_addf(&workdir_path, "%s/.git", argv[0]);
+		if (!is_directory(src_path.buf) && !is_directory(workdir_path.buf)) {
+			/* remove possible matching registrations */
+			int res = -1;
+
+			strbuf_strip_suffix(&src_path, "/.git");
+			res = remove_deleted_enlistment(&src_path) && res;
+
+			strbuf_strip_suffix(&workdir_path, "/.git");
+			res = remove_deleted_enlistment(&workdir_path) && res;
+
+			strbuf_release(&src_path);
+			strbuf_release(&workdir_path);
+			return res;
+		}
+		strbuf_release(&src_path);
+		strbuf_release(&workdir_path);
+	}
+
+	setup_enlistment_directory(argc, argv, usage, options, NULL);
+
+	return unregister_dir();
+}
+
+static int cmd_delete(int argc, const char **argv)
+{
+	char *cwd = xgetcwd();
+	struct option options[] = {
+		OPT_END(),
+	};
+	const char * const usage[] = {
+		N_("scalar delete <enlistment>"),
+		NULL
+	};
+	struct strbuf enlistment = STRBUF_INIT;
+	int res = 0;
+
+	argc = parse_options(argc, argv, NULL, options,
+			     usage, 0);
+
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	setup_enlistment_directory(argc, argv, usage, options, &enlistment);
+
+	if (dir_inside_of(cwd, enlistment.buf) >= 0)
+		res = error(_("refusing to delete current working directory"));
+	else {
+		close_object_store(the_repository->objects);
+		res = delete_enlistment(&enlistment);
+	}
+	strbuf_release(&enlistment);
+	free(cwd);
+
+	return res;
+}
+
+static int cmd_version(int argc, const char **argv)
+{
+	int verbose = 0, build_options = 0;
+	struct option options[] = {
+		OPT__VERBOSE(&verbose, N_("include Git version")),
+		OPT_BOOL(0, "build-options", &build_options,
+			 N_("include Git's build options")),
+		OPT_END(),
+	};
+	const char * const usage[] = {
+		N_("scalar verbose [-v | --verbose] [--build-options]"),
+		NULL
+	};
+	struct strbuf buf = STRBUF_INIT;
+
+	argc = parse_options(argc, argv, NULL, options,
+			     usage, 0);
+
+	if (argc != 0)
+		usage_with_options(usage, options);
+
+	get_version_info(&buf, build_options);
+	fprintf(stderr, "%s\n", buf.buf);
+	strbuf_release(&buf);
+
+	return 0;
+}
+
+static struct {
+	const char *name;
+	int (*fn)(int, const char **);
+} builtins[] = {
+	{ "clone", cmd_clone },
+	{ "list", cmd_list },
+	{ "register", cmd_register },
+	{ "unregister", cmd_unregister },
+	{ "run", cmd_run },
+	{ "reconfigure", cmd_reconfigure },
+	{ "delete", cmd_delete },
+	{ "version", cmd_version },
+	{ NULL, NULL},
+};
+
+int cmd_main(int argc, const char **argv)
+{
+	struct strbuf scalar_usage = STRBUF_INIT;
+	int i;
+
+	if (argc > 1) {
+		argv++;
+		argc--;
+
+		for (i = 0; builtins[i].name; i++)
+			if (!strcmp(builtins[i].name, argv[0]))
+				return !!builtins[i].fn(argc, argv);
+	}
+
+	strbuf_addstr(&scalar_usage,
+		      N_("scalar <command> [<options>]\n\nCommands:\n"));
+	for (i = 0; builtins[i].name; i++)
+		strbuf_addf(&scalar_usage, "\t%s\n", builtins[i].name);
+
+	usage(scalar_usage.buf);
+}
diff --git a/contrib/scalar/scalar.txt b/contrib/scalar/scalar.txt
new file mode 100644
index 0000000..f416d63
--- /dev/null
+++ b/contrib/scalar/scalar.txt
@@ -0,0 +1,145 @@
+scalar(1)
+=========
+
+NAME
+----
+scalar - an opinionated repository management tool
+
+SYNOPSIS
+--------
+[verse]
+scalar clone [--single-branch] [--branch <main-branch>] [--full-clone] <url> [<enlistment>]
+scalar list
+scalar register [<enlistment>]
+scalar unregister [<enlistment>]
+scalar run ( all | config | commit-graph | fetch | loose-objects | pack-files ) [<enlistment>]
+scalar reconfigure [ --all | <enlistment> ]
+scalar delete <enlistment>
+
+DESCRIPTION
+-----------
+
+Scalar is an opinionated repository management tool. By creating new
+repositories or registering existing repositories with Scalar, your Git
+experience will speed up. Scalar sets advanced Git config settings,
+maintains your repositories in the background, and helps reduce data sent
+across the network.
+
+An important Scalar concept is the enlistment: this is the top-level directory
+of the project. It usually contains the subdirectory `src/` which is a Git
+worktree. This encourages the separation between tracked files (inside `src/`)
+and untracked files, such as build artifacts (outside `src/`). When registering
+an existing Git worktree with Scalar whose name is not `src`, the enlistment
+will be identical to the worktree.
+
+The `scalar` command implements various subcommands, and different options
+depending on the subcommand. With the exception of `clone`, `list` and
+`reconfigure --all`, all subcommands expect to be run in an enlistment.
+
+COMMANDS
+--------
+
+Clone
+~~~~~
+
+clone [<options>] <url> [<enlistment>]::
+	Clones the specified repository, similar to linkgit:git-clone[1]. By
+	default, only commit and tree objects are cloned. Once finished, the
+	worktree is located at `<enlistment>/src`.
++
+The sparse-checkout feature is enabled (except when run with `--full-clone`)
+and the only files present are those in the top-level directory. Use
+`git sparse-checkout set` to expand the set of directories you want to see,
+or `git sparse-checkout disable` to expand to all files (see
+linkgit:git-sparse-checkout[1] for more details). You can explore the
+subdirectories outside your sparse-checkout by using `git ls-tree
+HEAD[:<directory>]`.
+
+-b <name>::
+--branch <name>::
+	Instead of checking out the branch pointed to by the cloned
+	repository's HEAD, check out the `<name>` branch instead.
+
+--[no-]single-branch::
+	Clone only the history leading to the tip of a single branch, either
+	specified by the `--branch` option or the primary branch remote's
+	`HEAD` points at.
++
+Further fetches into the resulting repository will only update the
+remote-tracking branch for the branch this option was used for the initial
+cloning. If the HEAD at the remote did not point at any branch when
+`--single-branch` clone was made, no remote-tracking branch is created.
+
+--[no-]full-clone::
+	A sparse-checkout is initialized by default. This behavior can be
+	turned off via `--full-clone`.
+
+List
+~~~~
+
+list::
+	List enlistments that are currently registered by Scalar. This
+	subcommand does not need to be run inside an enlistment.
+
+Register
+~~~~~~~~
+
+register [<enlistment>]::
+	Adds the enlistment's repository to the list of registered repositories
+	and starts background maintenance. If `<enlistment>` is not provided,
+	then the enlistment associated with the current working directory is
+	registered.
++
+Note: when this subcommand is called in a worktree that is called `src/`, its
+parent directory is considered to be the Scalar enlistment. If the worktree is
+_not_ called `src/`, it itself will be considered to be the Scalar enlistment.
+
+Unregister
+~~~~~~~~~~
+
+unregister [<enlistment>]::
+	Remove the specified repository from the list of repositories
+	registered with Scalar and stop the scheduled background maintenance.
+
+Run
+~~~
+
+scalar run ( all | config | commit-graph | fetch | loose-objects | pack-files ) [<enlistment>]::
+	Run the given maintenance task (or all tasks, if `all` was specified).
+	Except for `all` and `config`, this subcommand simply hands off to
+	linkgit:git-maintenance[1] (mapping `fetch` to `prefetch` and
+	`pack-files` to `incremental-repack`).
++
+These tasks are run automatically as part of the scheduled maintenance,
+as soon as the repository is registered with Scalar. It should therefore
+not be necessary to run this subcommand manually.
++
+The `config` task is specific to Scalar and configures all those
+opinionated default settings that make Git work more efficiently with
+large repositories. As this task is run as part of `scalar clone`
+automatically, explicit invocations of this task are rarely needed.
+
+Reconfigure
+~~~~~~~~~~~
+
+After a Scalar upgrade, or when the configuration of a Scalar enlistment
+was somehow corrupted or changed by mistake, this subcommand allows to
+reconfigure the enlistment.
+
+With the `--all` option, all enlistments currently registered with Scalar
+will be reconfigured. Use this option after each Scalar upgrade.
+
+Delete
+~~~~~~
+
+delete <enlistment>::
+	This subcommand lets you delete an existing Scalar enlistment from your
+	local file system, unregistering the repository.
+
+SEE ALSO
+--------
+linkgit:git-clone[1], linkgit:git-maintenance[1].
+
+Scalar
+---
+Associated with the linkgit:git[1] suite
diff --git a/contrib/scalar/t/Makefile b/contrib/scalar/t/Makefile
new file mode 100644
index 0000000..6170672
--- /dev/null
+++ b/contrib/scalar/t/Makefile
@@ -0,0 +1,78 @@
+# Run scalar tests
+#
+# Copyright (c) 2005,2021 Junio C Hamano, Johannes Schindelin
+#
+
+-include ../../../config.mak.autogen
+-include ../../../config.mak
+
+SHELL_PATH ?= $(SHELL)
+PERL_PATH ?= /usr/bin/perl
+RM ?= rm -f
+PROVE ?= prove
+DEFAULT_TEST_TARGET ?= test
+TEST_LINT ?= test-lint
+
+ifdef TEST_OUTPUT_DIRECTORY
+TEST_RESULTS_DIRECTORY = $(TEST_OUTPUT_DIRECTORY)/test-results
+else
+TEST_RESULTS_DIRECTORY = ../../../t/test-results
+endif
+
+# Shell quote;
+SHELL_PATH_SQ = $(subst ','\'',$(SHELL_PATH))
+PERL_PATH_SQ = $(subst ','\'',$(PERL_PATH))
+TEST_RESULTS_DIRECTORY_SQ = $(subst ','\'',$(TEST_RESULTS_DIRECTORY))
+
+T = $(sort $(wildcard t[0-9][0-9][0-9][0-9]-*.sh))
+
+all: $(DEFAULT_TEST_TARGET)
+
+test: $(TEST_LINT)
+	$(MAKE) aggregate-results-and-cleanup
+
+prove: $(TEST_LINT)
+	@echo "*** prove ***"; GIT_CONFIG=.git/config $(PROVE) --exec '$(SHELL_PATH_SQ)' $(GIT_PROVE_OPTS) $(T) :: $(GIT_TEST_OPTS)
+	$(MAKE) clean-except-prove-cache
+
+$(T):
+	@echo "*** $@ ***"; GIT_CONFIG=.git/config '$(SHELL_PATH_SQ)' $@ $(GIT_TEST_OPTS)
+
+clean-except-prove-cache:
+	$(RM) -r 'trash directory'.* '$(TEST_RESULTS_DIRECTORY_SQ)'
+	$(RM) -r valgrind/bin
+
+clean: clean-except-prove-cache
+	$(RM) .prove
+
+test-lint: test-lint-duplicates test-lint-executable test-lint-shell-syntax
+
+test-lint-duplicates:
+	@dups=`echo $(T) | tr ' ' '\n' | sed 's/-.*//' | sort | uniq -d` && \
+		test -z "$$dups" || { \
+		echo >&2 "duplicate test numbers:" $$dups; exit 1; }
+
+test-lint-executable:
+	@bad=`for i in $(T); do test -x "$$i" || echo $$i; done` && \
+		test -z "$$bad" || { \
+		echo >&2 "non-executable tests:" $$bad; exit 1; }
+
+test-lint-shell-syntax:
+	@'$(PERL_PATH_SQ)' ../../../t/check-non-portable-shell.pl $(T)
+
+aggregate-results-and-cleanup: $(T)
+	$(MAKE) aggregate-results
+	$(MAKE) clean
+
+aggregate-results:
+	for f in '$(TEST_RESULTS_DIRECTORY_SQ)'/t*-*.counts; do \
+		echo "$$f"; \
+	done | '$(SHELL_PATH_SQ)' ../../../t/aggregate-results.sh
+
+valgrind:
+	$(MAKE) GIT_TEST_OPTS="$(GIT_TEST_OPTS) --valgrind"
+
+test-results:
+	mkdir -p test-results
+
+.PHONY: $(T) aggregate-results clean valgrind
diff --git a/contrib/scalar/t/t9099-scalar.sh b/contrib/scalar/t/t9099-scalar.sh
new file mode 100755
index 0000000..2e1502a
--- /dev/null
+++ b/contrib/scalar/t/t9099-scalar.sh
@@ -0,0 +1,88 @@
+#!/bin/sh
+
+test_description='test the `scalar` command'
+
+TEST_DIRECTORY=$PWD/../../../t
+export TEST_DIRECTORY
+
+# Make it work with --no-bin-wrappers
+PATH=$PWD/..:$PATH
+
+. ../../../t/test-lib.sh
+
+GIT_TEST_MAINT_SCHEDULER="crontab:test-tool crontab ../cron.txt,launchctl:true,schtasks:true"
+export GIT_TEST_MAINT_SCHEDULER
+
+test_expect_success 'scalar shows a usage' '
+	test_expect_code 129 scalar -h
+'
+
+test_expect_success 'scalar unregister' '
+	git init vanish/src &&
+	scalar register vanish/src &&
+	git config --get --global --fixed-value \
+		maintenance.repo "$(pwd)/vanish/src" &&
+	scalar list >scalar.repos &&
+	grep -F "$(pwd)/vanish/src" scalar.repos &&
+	rm -rf vanish/src/.git &&
+	scalar unregister vanish &&
+	test_must_fail git config --get --global --fixed-value \
+		maintenance.repo "$(pwd)/vanish/src" &&
+	scalar list >scalar.repos &&
+	! grep -F "$(pwd)/vanish/src" scalar.repos
+'
+
+test_expect_success 'set up repository to clone' '
+	test_commit first &&
+	test_commit second &&
+	test_commit third &&
+	git switch -c parallel first &&
+	mkdir -p 1/2 &&
+	test_commit 1/2/3 &&
+	git config uploadPack.allowFilter true &&
+	git config uploadPack.allowAnySHA1InWant true
+'
+
+test_expect_success 'scalar clone' '
+	second=$(git rev-parse --verify second:second.t) &&
+	scalar clone "file://$(pwd)" cloned --single-branch &&
+	(
+		cd cloned/src &&
+
+		git config --get --global --fixed-value maintenance.repo \
+			"$(pwd)" &&
+
+		git for-each-ref --format="%(refname)" refs/remotes/origin/ >actual &&
+		echo "refs/remotes/origin/parallel" >expect &&
+		test_cmp expect actual &&
+
+		test_path_is_missing 1/2 &&
+		test_must_fail git rev-list --missing=print $second &&
+		git rev-list $second &&
+		git cat-file blob $second >actual &&
+		echo "second" >expect &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'scalar reconfigure' '
+	git init one/src &&
+	scalar register one &&
+	git -C one/src config core.preloadIndex false &&
+	scalar reconfigure one &&
+	test true = "$(git -C one/src config core.preloadIndex)" &&
+	git -C one/src config core.preloadIndex false &&
+	scalar reconfigure -a &&
+	test true = "$(git -C one/src config core.preloadIndex)"
+'
+
+test_expect_success 'scalar delete without enlistment shows a usage' '
+	test_expect_code 129 scalar delete
+'
+
+test_expect_success 'scalar delete with enlistment' '
+	scalar delete cloned &&
+	test_path_is_missing cloned
+'
+
+test_done
diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh
index 7f767b5..71f1fd9 100755
--- a/contrib/subtree/git-subtree.sh
+++ b/contrib/subtree/git-subtree.sh
@@ -296,10 +296,9 @@
 	done
 }
 
-# Usage: check_parents PARENTS_EXPR
+# Usage: check_parents [REVS...]
 check_parents () {
-	assert test $# = 1
-	missed=$(cache_miss "$1") || exit $?
+	missed=$(cache_miss "$@") || exit $?
 	local indent=$(($indent + 1))
 	for miss in $missed
 	do
@@ -753,7 +752,7 @@
 	fi
 	createcount=$(($createcount + 1))
 	debug "parents: $parents"
-	check_parents "$parents"
+	check_parents $parents
 	newparents=$(cache_get $parents) || exit $?
 	debug "newparents: $newparents"
 
diff --git a/contrib/subtree/t/t7900-subtree.sh b/contrib/subtree/t/t7900-subtree.sh
index 4153b65..1c1f76f 100755
--- a/contrib/subtree/t/t7900-subtree.sh
+++ b/contrib/subtree/t/t7900-subtree.sh
@@ -1445,7 +1445,7 @@
 	) &&
 	test_create_commit "$test_count" folder_subtree/0 &&
 	test_create_commit "$test_count" folder_subtree/b &&
-	cherry=$(cd "$test_count"; git rev-parse HEAD) &&
+	cherry=$(cd "$test_count" && git rev-parse HEAD) &&
 	(
 		cd "$test_count" &&
 		git checkout branch
diff --git a/convert.c b/convert.c
index 0d6fb34..df7186b 100644
--- a/convert.c
+++ b/convert.c
@@ -613,7 +613,7 @@
 
 struct filter_params {
 	const char *src;
-	unsigned long size;
+	size_t size;
 	int fd;
 	const char *cmd;
 	const char *path;
diff --git a/daemon.c b/daemon.c
index b1fcbe0..94a5b8a 100644
--- a/daemon.c
+++ b/daemon.c
@@ -232,13 +232,13 @@
 
 		rlen = strlcpy(interp_path, expanded_path.buf,
 			       sizeof(interp_path));
+		strbuf_release(&expanded_path);
 		if (rlen >= sizeof(interp_path)) {
 			logerror("interpolated path too large: %s",
 				 interp_path);
 			return NULL;
 		}
 
-		strbuf_release(&expanded_path);
 		loginfo("Interpolated dir '%s'", interp_path);
 
 		dir = interp_path;
@@ -326,22 +326,18 @@
 {
 	struct child_process child = CHILD_PROCESS_INIT;
 	struct strbuf buf = STRBUF_INIT;
-	const char *argv[8];
-	const char **arg = argv;
 	char *eol;
 	int seen_errors = 0;
 
-	*arg++ = access_hook;
-	*arg++ = service->name;
-	*arg++ = path;
-	*arg++ = hi->hostname.buf;
-	*arg++ = get_canon_hostname(hi);
-	*arg++ = get_ip_address(hi);
-	*arg++ = hi->tcp_port.buf;
-	*arg = NULL;
+	strvec_push(&child.args, access_hook);
+	strvec_push(&child.args, service->name);
+	strvec_push(&child.args, path);
+	strvec_push(&child.args, hi->hostname.buf);
+	strvec_push(&child.args, get_canon_hostname(hi));
+	strvec_push(&child.args, get_ip_address(hi));
+	strvec_push(&child.args, hi->tcp_port.buf);
 
 	child.use_shell = 1;
-	child.argv = argv;
 	child.no_stdin = 1;
 	child.no_stderr = 1;
 	child.out = -1;
@@ -922,7 +918,7 @@
 #endif
 	}
 
-	cld.argv = cld_argv.v;
+	strvec_pushv(&cld.args, cld_argv.v);
 	cld.in = incoming;
 	cld.out = dup(incoming);
 
diff --git a/date.c b/date.c
index c55ea47..84bb445 100644
--- a/date.c
+++ b/date.c
@@ -9,7 +9,7 @@
 /*
  * This is like mktime, but without normalization of tm_wday and tm_yday.
  */
-static time_t tm_to_time_t(const struct tm *tm)
+time_t tm_to_time_t(const struct tm *tm)
 {
 	static const int mdays[] = {
 	    0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
diff --git a/delta.h b/delta.h
index 2df5fe1..8a56ec0 100644
--- a/delta.h
+++ b/delta.h
@@ -90,15 +90,15 @@
 					       const unsigned char *top)
 {
 	const unsigned char *data = *datap;
-	unsigned long cmd, size = 0;
+	size_t cmd, size = 0;
 	int i = 0;
 	do {
 		cmd = *data++;
-		size |= (cmd & 0x7f) << i;
+		size |= st_left_shift(cmd & 0x7f, i);
 		i += 7;
 	} while (cmd & 0x80 && data < top);
 	*datap = data;
-	return size;
+	return cast_size_t_to_ulong(size);
 }
 
 #endif
diff --git a/diff.c b/diff.c
index 861282d..c862771 100644
--- a/diff.c
+++ b/diff.c
@@ -18,6 +18,7 @@
 #include "submodule-config.h"
 #include "submodule.h"
 #include "hashmap.h"
+#include "mem-pool.h"
 #include "ll-merge.h"
 #include "string-list.h"
 #include "strvec.h"
@@ -773,6 +774,7 @@
 	int flags;
 	int indent_off;   /* Offset to first non-whitespace character */
 	int indent_width; /* The visual width of the indentation */
+	unsigned id;
 	enum diff_symbol s;
 };
 #define EMITTED_DIFF_SYMBOL_INIT { 0 }
@@ -798,9 +800,9 @@
 }
 
 struct moved_entry {
-	struct hashmap_entry ent;
 	const struct emitted_diff_symbol *es;
 	struct moved_entry *next_line;
+	struct moved_entry *next_match;
 };
 
 struct moved_block {
@@ -808,11 +810,6 @@
 	int wsd; /* The whitespace delta of this block */
 };
 
-static void moved_block_clear(struct moved_block *b)
-{
-	memset(b, 0, sizeof(*b));
-}
-
 #define INDENT_BLANKLINE INT_MIN
 
 static void fill_es_indent_data(struct emitted_diff_symbol *es)
@@ -856,79 +853,41 @@
 }
 
 static int compute_ws_delta(const struct emitted_diff_symbol *a,
-			    const struct emitted_diff_symbol *b,
-			    int *out)
+			    const struct emitted_diff_symbol *b)
 {
-	int a_len = a->len,
-	    b_len = b->len,
-	    a_off = a->indent_off,
-	    a_width = a->indent_width,
-	    b_off = b->indent_off,
+	int a_width = a->indent_width,
 	    b_width = b->indent_width;
-	int delta;
 
-	if (a_width == INDENT_BLANKLINE && b_width == INDENT_BLANKLINE) {
-		*out = INDENT_BLANKLINE;
-		return 1;
-	}
+	if (a_width == INDENT_BLANKLINE && b_width == INDENT_BLANKLINE)
+		return INDENT_BLANKLINE;
 
-	if (a->s == DIFF_SYMBOL_PLUS)
-		delta = a_width - b_width;
-	else
-		delta = b_width - a_width;
-
-	if (a_len - a_off != b_len - b_off ||
-	    memcmp(a->line + a_off, b->line + b_off, a_len - a_off))
-		return 0;
-
-	*out = delta;
-
-	return 1;
+	return a_width - b_width;
 }
 
-static int cmp_in_block_with_wsd(const struct diff_options *o,
-				 const struct moved_entry *cur,
-				 const struct moved_entry *match,
-				 struct moved_block *pmb,
-				 int n)
+static int cmp_in_block_with_wsd(const struct moved_entry *cur,
+				 const struct emitted_diff_symbol *l,
+				 struct moved_block *pmb)
 {
-	struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
-	int al = cur->es->len, bl = match->es->len, cl = l->len;
-	const char *a = cur->es->line,
-		   *b = match->es->line,
-		   *c = l->line;
-	int a_off = cur->es->indent_off,
-	    a_width = cur->es->indent_width,
-	    c_off = l->indent_off,
-	    c_width = l->indent_width;
+	int a_width = cur->es->indent_width, b_width = l->indent_width;
 	int delta;
 
-	/*
-	 * We need to check if 'cur' is equal to 'match'.  As those
-	 * are from the same (+/-) side, we do not need to adjust for
-	 * indent changes. However these were found using fuzzy
-	 * matching so we do have to check if they are equal. Here we
-	 * just check the lengths. We delay calling memcmp() to check
-	 * the contents until later as if the length comparison for a
-	 * and c fails we can avoid the call all together.
-	 */
-	if (al != bl)
+	/* The text of each line must match */
+	if (cur->es->id != l->id)
 		return 1;
 
-	/* If 'l' and 'cur' are both blank then they match. */
-	if (a_width == INDENT_BLANKLINE && c_width == INDENT_BLANKLINE)
+	/*
+	 * If 'l' and 'cur' are both blank then we don't need to check the
+	 * indent. We only need to check cur as we know the strings match.
+	 * */
+	if (a_width == INDENT_BLANKLINE)
 		return 0;
 
 	/*
 	 * The indent changes of the block are known and stored in pmb->wsd;
 	 * however we need to check if the indent changes of the current line
-	 * match those of the current block and that the text of 'l' and 'cur'
-	 * after the indentation match.
+	 * match those of the current block.
 	 */
-	if (cur->es->s == DIFF_SYMBOL_PLUS)
-		delta = a_width - c_width;
-	else
-		delta = c_width - a_width;
+	delta = b_width - a_width;
 
 	/*
 	 * If the previous lines of this block were all blank then set its
@@ -937,166 +896,165 @@
 	if (pmb->wsd == INDENT_BLANKLINE)
 		pmb->wsd = delta;
 
-	return !(delta == pmb->wsd && al - a_off == cl - c_off &&
-		 !memcmp(a, b, al) && !
-		 memcmp(a + a_off, c + c_off, al - a_off));
+	return delta != pmb->wsd;
 }
 
-static int moved_entry_cmp(const void *hashmap_cmp_fn_data,
-			   const struct hashmap_entry *eptr,
-			   const struct hashmap_entry *entry_or_key,
-			   const void *keydata)
+struct interned_diff_symbol {
+	struct hashmap_entry ent;
+	struct emitted_diff_symbol *es;
+};
+
+static int interned_diff_symbol_cmp(const void *hashmap_cmp_fn_data,
+				    const struct hashmap_entry *eptr,
+				    const struct hashmap_entry *entry_or_key,
+				    const void *keydata)
 {
 	const struct diff_options *diffopt = hashmap_cmp_fn_data;
-	const struct moved_entry *a, *b;
+	const struct emitted_diff_symbol *a, *b;
 	unsigned flags = diffopt->color_moved_ws_handling
 			 & XDF_WHITESPACE_FLAGS;
 
-	a = container_of(eptr, const struct moved_entry, ent);
-	b = container_of(entry_or_key, const struct moved_entry, ent);
+	a = container_of(eptr, const struct interned_diff_symbol, ent)->es;
+	b = container_of(entry_or_key, const struct interned_diff_symbol, ent)->es;
 
-	if (diffopt->color_moved_ws_handling &
-	    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
-		/*
-		 * As there is not specific white space config given,
-		 * we'd need to check for a new block, so ignore all
-		 * white space. The setup of the white space
-		 * configuration for the next block is done else where
-		 */
-		flags |= XDF_IGNORE_WHITESPACE;
-
-	return !xdiff_compare_lines(a->es->line, a->es->len,
-				    b->es->line, b->es->len,
-				    flags);
+	return !xdiff_compare_lines(a->line + a->indent_off,
+				    a->len - a->indent_off,
+				    b->line + b->indent_off,
+				    b->len - b->indent_off, flags);
 }
 
-static struct moved_entry *prepare_entry(struct diff_options *o,
-					 int line_no)
+static void prepare_entry(struct diff_options *o, struct emitted_diff_symbol *l,
+			  struct interned_diff_symbol *s)
 {
-	struct moved_entry *ret = xmalloc(sizeof(*ret));
-	struct emitted_diff_symbol *l = &o->emitted_symbols->buf[line_no];
 	unsigned flags = o->color_moved_ws_handling & XDF_WHITESPACE_FLAGS;
-	unsigned int hash = xdiff_hash_string(l->line, l->len, flags);
+	unsigned int hash = xdiff_hash_string(l->line + l->indent_off,
+					      l->len - l->indent_off, flags);
 
-	hashmap_entry_init(&ret->ent, hash);
-	ret->es = l;
-	ret->next_line = NULL;
-
-	return ret;
+	hashmap_entry_init(&s->ent, hash);
+	s->es = l;
 }
 
-static void add_lines_to_move_detection(struct diff_options *o,
-					struct hashmap *add_lines,
-					struct hashmap *del_lines)
+struct moved_entry_list {
+	struct moved_entry *add, *del;
+};
+
+static struct moved_entry_list *add_lines_to_move_detection(struct diff_options *o,
+							    struct mem_pool *entry_mem_pool)
 {
 	struct moved_entry *prev_line = NULL;
-
+	struct mem_pool interned_pool;
+	struct hashmap interned_map;
+	struct moved_entry_list *entry_list = NULL;
+	size_t entry_list_alloc = 0;
+	unsigned id = 0;
 	int n;
-	for (n = 0; n < o->emitted_symbols->nr; n++) {
-		struct hashmap *hm;
-		struct moved_entry *key;
 
-		switch (o->emitted_symbols->buf[n].s) {
-		case DIFF_SYMBOL_PLUS:
-			hm = add_lines;
-			break;
-		case DIFF_SYMBOL_MINUS:
-			hm = del_lines;
-			break;
-		default:
+	hashmap_init(&interned_map, interned_diff_symbol_cmp, o, 8096);
+	mem_pool_init(&interned_pool, 1024 * 1024);
+
+	for (n = 0; n < o->emitted_symbols->nr; n++) {
+		struct interned_diff_symbol key;
+		struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
+		struct interned_diff_symbol *s;
+		struct moved_entry *entry;
+
+		if (l->s != DIFF_SYMBOL_PLUS && l->s != DIFF_SYMBOL_MINUS) {
 			prev_line = NULL;
 			continue;
 		}
 
 		if (o->color_moved_ws_handling &
 		    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
-			fill_es_indent_data(&o->emitted_symbols->buf[n]);
-		key = prepare_entry(o, n);
-		if (prev_line && prev_line->es->s == o->emitted_symbols->buf[n].s)
-			prev_line->next_line = key;
+			fill_es_indent_data(l);
 
-		hashmap_add(hm, &key->ent);
-		prev_line = key;
+		prepare_entry(o, l, &key);
+		s = hashmap_get_entry(&interned_map, &key, ent, &key.ent);
+		if (s) {
+			l->id = s->es->id;
+		} else {
+			l->id = id;
+			ALLOC_GROW_BY(entry_list, id, 1, entry_list_alloc);
+			hashmap_add(&interned_map,
+				    memcpy(mem_pool_alloc(&interned_pool,
+							  sizeof(key)),
+					   &key, sizeof(key)));
+		}
+		entry = mem_pool_alloc(entry_mem_pool, sizeof(*entry));
+		entry->es = l;
+		entry->next_line = NULL;
+		if (prev_line && prev_line->es->s == l->s)
+			prev_line->next_line = entry;
+		prev_line = entry;
+		if (l->s == DIFF_SYMBOL_PLUS) {
+			entry->next_match = entry_list[l->id].add;
+			entry_list[l->id].add = entry;
+		} else {
+			entry->next_match = entry_list[l->id].del;
+			entry_list[l->id].del = entry;
+		}
 	}
+
+	hashmap_clear(&interned_map);
+	mem_pool_discard(&interned_pool, 0);
+
+	return entry_list;
 }
 
 static void pmb_advance_or_null(struct diff_options *o,
-				struct moved_entry *match,
-				struct hashmap *hm,
+				struct emitted_diff_symbol *l,
 				struct moved_block *pmb,
-				int pmb_nr)
+				int *pmb_nr)
 {
-	int i;
-	for (i = 0; i < pmb_nr; i++) {
+	int i, j;
+
+	for (i = 0, j = 0; i < *pmb_nr; i++) {
+		int match;
 		struct moved_entry *prev = pmb[i].match;
 		struct moved_entry *cur = (prev && prev->next_line) ?
 				prev->next_line : NULL;
-		if (cur && !hm->cmpfn(o, &cur->ent, &match->ent, NULL)) {
-			pmb[i].match = cur;
-		} else {
-			pmb[i].match = NULL;
+
+		if (o->color_moved_ws_handling &
+		    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
+			match = cur &&
+				!cmp_in_block_with_wsd(cur, l, &pmb[i]);
+		else
+			match = cur && cur->es->id == l->id;
+
+		if (match) {
+			pmb[j] = pmb[i];
+			pmb[j++].match = cur;
 		}
 	}
+	*pmb_nr = j;
 }
 
-static void pmb_advance_or_null_multi_match(struct diff_options *o,
-					    struct moved_entry *match,
-					    struct hashmap *hm,
-					    struct moved_block *pmb,
-					    int pmb_nr, int n)
+static void fill_potential_moved_blocks(struct diff_options *o,
+					struct moved_entry *match,
+					struct emitted_diff_symbol *l,
+					struct moved_block **pmb_p,
+					int *pmb_alloc_p, int *pmb_nr_p)
+
 {
-	int i;
-	char *got_match = xcalloc(1, pmb_nr);
+	struct moved_block *pmb = *pmb_p;
+	int pmb_alloc = *pmb_alloc_p, pmb_nr = *pmb_nr_p;
 
-	hashmap_for_each_entry_from(hm, match, ent) {
-		for (i = 0; i < pmb_nr; i++) {
-			struct moved_entry *prev = pmb[i].match;
-			struct moved_entry *cur = (prev && prev->next_line) ?
-					prev->next_line : NULL;
-			if (!cur)
-				continue;
-			if (!cmp_in_block_with_wsd(o, cur, match, &pmb[i], n))
-				got_match[i] |= 1;
-		}
+	/*
+	 * The current line is the start of a new block.
+	 * Setup the set of potential blocks.
+	 */
+	for (; match; match = match->next_match) {
+		ALLOC_GROW(pmb, pmb_nr + 1, pmb_alloc);
+		if (o->color_moved_ws_handling &
+		    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
+			pmb[pmb_nr].wsd = compute_ws_delta(l, match->es);
+		else
+			pmb[pmb_nr].wsd = 0;
+		pmb[pmb_nr++].match = match;
 	}
 
-	for (i = 0; i < pmb_nr; i++) {
-		if (got_match[i]) {
-			/* Advance to the next line */
-			pmb[i].match = pmb[i].match->next_line;
-		} else {
-			moved_block_clear(&pmb[i]);
-		}
-	}
-
-	free(got_match);
-}
-
-static int shrink_potential_moved_blocks(struct moved_block *pmb,
-					 int pmb_nr)
-{
-	int lp, rp;
-
-	/* Shrink the set of potential block to the remaining running */
-	for (lp = 0, rp = pmb_nr - 1; lp <= rp;) {
-		while (lp < pmb_nr && pmb[lp].match)
-			lp++;
-		/* lp points at the first NULL now */
-
-		while (rp > -1 && !pmb[rp].match)
-			rp--;
-		/* rp points at the last non-NULL */
-
-		if (lp < pmb_nr && rp > -1 && lp < rp) {
-			pmb[lp] = pmb[rp];
-			memset(&pmb[rp], 0, sizeof(pmb[rp]));
-			rp--;
-			lp++;
-		}
-	}
-
-	/* Remember the number of running sets */
-	return rp + 1;
+	*pmb_p = pmb;
+	*pmb_alloc_p = pmb_alloc;
+	*pmb_nr_p = pmb_nr;
 }
 
 /*
@@ -1115,6 +1073,8 @@
  * NEEDSWORK: This uses the same heuristic as blame_entry_score() in blame.c.
  * Think of a way to unify them.
  */
+#define DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK \
+  (DIFF_SYMBOL_MOVED_LINE | DIFF_SYMBOL_MOVED_LINE_ALT)
 static int adjust_last_block(struct diff_options *o, int n, int block_length)
 {
 	int i, alnum_count = 0;
@@ -1131,95 +1091,85 @@
 		}
 	}
 	for (i = 1; i < block_length + 1; i++)
-		o->emitted_symbols->buf[n - i].flags &= ~DIFF_SYMBOL_MOVED_LINE;
+		o->emitted_symbols->buf[n - i].flags &= ~DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK;
 	return 0;
 }
 
 /* Find blocks of moved code, delegate actual coloring decision to helper */
 static void mark_color_as_moved(struct diff_options *o,
-				struct hashmap *add_lines,
-				struct hashmap *del_lines)
+				struct moved_entry_list *entry_list)
 {
 	struct moved_block *pmb = NULL; /* potentially moved blocks */
 	int pmb_nr = 0, pmb_alloc = 0;
 	int n, flipped_block = 0, block_length = 0;
+	enum diff_symbol moved_symbol = DIFF_SYMBOL_BINARY_DIFF_HEADER;
 
 
 	for (n = 0; n < o->emitted_symbols->nr; n++) {
-		struct hashmap *hm = NULL;
-		struct moved_entry *key;
 		struct moved_entry *match = NULL;
 		struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
-		enum diff_symbol last_symbol = 0;
 
 		switch (l->s) {
 		case DIFF_SYMBOL_PLUS:
-			hm = del_lines;
-			key = prepare_entry(o, n);
-			match = hashmap_get_entry(hm, key, ent, NULL);
-			free(key);
+			match = entry_list[l->id].del;
 			break;
 		case DIFF_SYMBOL_MINUS:
-			hm = add_lines;
-			key = prepare_entry(o, n);
-			match = hashmap_get_entry(hm, key, ent, NULL);
-			free(key);
+			match = entry_list[l->id].add;
 			break;
 		default:
 			flipped_block = 0;
 		}
 
-		if (!match) {
-			int i;
-
-			adjust_last_block(o, n, block_length);
-			for(i = 0; i < pmb_nr; i++)
-				moved_block_clear(&pmb[i]);
+		if (pmb_nr && (!match || l->s != moved_symbol)) {
+			if (!adjust_last_block(o, n, block_length) &&
+			    block_length > 1) {
+				/*
+				 * Rewind in case there is another match
+				 * starting at the second line of the block
+				 */
+				match = NULL;
+				n -= block_length;
+			}
 			pmb_nr = 0;
 			block_length = 0;
 			flipped_block = 0;
-			last_symbol = l->s;
+		}
+		if (!match) {
+			moved_symbol = DIFF_SYMBOL_BINARY_DIFF_HEADER;
 			continue;
 		}
 
 		if (o->color_moved == COLOR_MOVED_PLAIN) {
-			last_symbol = l->s;
 			l->flags |= DIFF_SYMBOL_MOVED_LINE;
 			continue;
 		}
 
-		if (o->color_moved_ws_handling &
-		    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
-			pmb_advance_or_null_multi_match(o, match, hm, pmb, pmb_nr, n);
-		else
-			pmb_advance_or_null(o, match, hm, pmb, pmb_nr);
-
-		pmb_nr = shrink_potential_moved_blocks(pmb, pmb_nr);
+		pmb_advance_or_null(o, l, pmb, &pmb_nr);
 
 		if (pmb_nr == 0) {
-			/*
-			 * The current line is the start of a new block.
-			 * Setup the set of potential blocks.
-			 */
-			hashmap_for_each_entry_from(hm, match, ent) {
-				ALLOC_GROW(pmb, pmb_nr + 1, pmb_alloc);
-				if (o->color_moved_ws_handling &
-				    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) {
-					if (compute_ws_delta(l, match->es,
-							     &pmb[pmb_nr].wsd))
-						pmb[pmb_nr++].match = match;
-				} else {
-					pmb[pmb_nr].wsd = 0;
-					pmb[pmb_nr++].match = match;
-				}
-			}
+			int contiguous = adjust_last_block(o, n, block_length);
 
-			if (adjust_last_block(o, n, block_length) &&
-			    pmb_nr && last_symbol != l->s)
+			if (!contiguous && block_length > 1)
+				/*
+				 * Rewind in case there is another match
+				 * starting at the second line of the block
+				 */
+				n -= block_length;
+			else
+				fill_potential_moved_blocks(o, match, l,
+							    &pmb, &pmb_alloc,
+							    &pmb_nr);
+
+			if (contiguous && pmb_nr && moved_symbol == l->s)
 				flipped_block = (flipped_block + 1) % 2;
 			else
 				flipped_block = 0;
 
+			if (pmb_nr)
+				moved_symbol = l->s;
+			else
+				moved_symbol = DIFF_SYMBOL_BINARY_DIFF_HEADER;
+
 			block_length = 0;
 		}
 
@@ -1229,17 +1179,12 @@
 			if (flipped_block && o->color_moved != COLOR_MOVED_BLOCKS)
 				l->flags |= DIFF_SYMBOL_MOVED_LINE_ALT;
 		}
-		last_symbol = l->s;
 	}
 	adjust_last_block(o, n, block_length);
 
-	for(n = 0; n < pmb_nr; n++)
-		moved_block_clear(&pmb[n]);
 	free(pmb);
 }
 
-#define DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK \
-  (DIFF_SYMBOL_MOVED_LINE | DIFF_SYMBOL_MOVED_LINE_ALT)
 static void dim_moved_lines(struct diff_options *o)
 {
 	int n;
@@ -1573,7 +1518,9 @@
 static void emit_diff_symbol(struct diff_options *o, enum diff_symbol s,
 			     const char *line, int len, unsigned flags)
 {
-	struct emitted_diff_symbol e = {line, len, flags, 0, 0, s};
+	struct emitted_diff_symbol e = {
+		.line = line, .len = len, .flags = flags, .s = s
+	};
 
 	if (o->emitted_symbols)
 		append_emitted_diff_symbol(o, &e);
@@ -4639,16 +4586,20 @@
 		options->set_default(options);
 
 	if (HAS_MULTI_BITS(options->output_format & check_mask))
-		die(_("--name-only, --name-status, --check and -s are mutually exclusive"));
+		die(_("options '%s', '%s', '%s', and '%s' cannot be used together"),
+			"--name-only", "--name-status", "--check", "-s");
 
 	if (HAS_MULTI_BITS(options->pickaxe_opts & DIFF_PICKAXE_KINDS_MASK))
-		die(_("-G, -S and --find-object are mutually exclusive"));
+		die(_("options '%s', '%s', and '%s' cannot be used together"),
+			"-G", "-S", "--find-object");
 
 	if (HAS_MULTI_BITS(options->pickaxe_opts & DIFF_PICKAXE_KINDS_G_REGEX_MASK))
-		die(_("-G and --pickaxe-regex are mutually exclusive, use --pickaxe-regex with -S"));
+		die(_("options '%s' and '%s' cannot be used together, use '%s' with '%s'"),
+			"-G", "--pickaxe-regex", "--pickaxe-regex", "-S");
 
 	if (HAS_MULTI_BITS(options->pickaxe_opts & DIFF_PICKAXE_KINDS_ALL_OBJFIND_MASK))
-		die(_("--pickaxe-all and --find-object are mutually exclusive, use --pickaxe-all with -G and -S"));
+		die(_("options '%s' and '%s' cannot be used together, use '%s' with '%s' and '%s'"),
+			"--pickaxe-all", "--find-object", "--pickaxe-all", "-G", "-S");
 
 	/*
 	 * Most of the time we can say "there are changes"
@@ -6345,24 +6296,18 @@
 
 	if (o->emitted_symbols) {
 		if (o->color_moved) {
-			struct hashmap add_lines, del_lines;
+			struct mem_pool entry_pool;
+			struct moved_entry_list *entry_list;
 
-			if (o->color_moved_ws_handling &
-			    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
-				o->color_moved_ws_handling |= XDF_IGNORE_WHITESPACE;
-
-			hashmap_init(&del_lines, moved_entry_cmp, o, 0);
-			hashmap_init(&add_lines, moved_entry_cmp, o, 0);
-
-			add_lines_to_move_detection(o, &add_lines, &del_lines);
-			mark_color_as_moved(o, &add_lines, &del_lines);
+			mem_pool_init(&entry_pool, 1024 * 1024);
+			entry_list = add_lines_to_move_detection(o,
+								 &entry_pool);
+			mark_color_as_moved(o, entry_list);
 			if (o->color_moved == COLOR_MOVED_ZEBRA_DIM)
 				dim_moved_lines(o);
 
-			hashmap_clear_and_free(&add_lines, struct moved_entry,
-						ent);
-			hashmap_clear_and_free(&del_lines, struct moved_entry,
-						ent);
+			mem_pool_discard(&entry_pool, 0);
+			free(entry_list);
 		}
 
 		for (i = 0; i < esm.nr; i++)
@@ -6921,19 +6866,15 @@
 			  size_t *outsize)
 {
 	struct diff_tempfile *temp;
-	const char *argv[3];
-	const char **arg = argv;
 	struct child_process child = CHILD_PROCESS_INIT;
 	struct strbuf buf = STRBUF_INIT;
 	int err = 0;
 
 	temp = prepare_temp_file(r, spec->path, spec);
-	*arg++ = pgm;
-	*arg++ = temp->name;
-	*arg = NULL;
+	strvec_push(&child.args, pgm);
+	strvec_push(&child.args, temp->name);
 
 	child.use_shell = 1;
-	child.argv = argv;
 	child.out = -1;
 	if (start_command(&child)) {
 		remove_tempfile();
diff --git a/diffcore-delta.c b/diffcore-delta.c
index 5668ace..18d8f76 100644
--- a/diffcore-delta.c
+++ b/diffcore-delta.c
@@ -133,10 +133,10 @@
 
 	i = INITIAL_HASH_SIZE;
 	hash = xmalloc(st_add(sizeof(*hash),
-			      st_mult(sizeof(struct spanhash), 1<<i)));
+			      st_mult(sizeof(struct spanhash), (size_t)1 << i)));
 	hash->alloc_log2 = i;
 	hash->free = INITIAL_FREE(i);
-	memset(hash->data, 0, sizeof(struct spanhash) * (1<<i));
+	memset(hash->data, 0, sizeof(struct spanhash) * ((size_t)1 << i));
 
 	n = 0;
 	accum1 = accum2 = 0;
@@ -159,7 +159,7 @@
 		n = 0;
 		accum1 = accum2 = 0;
 	}
-	QSORT(hash->data, 1ul << hash->alloc_log2, spanhash_cmp);
+	QSORT(hash->data, (size_t)1ul << hash->alloc_log2, spanhash_cmp);
 	return hash;
 }
 
diff --git a/dir.c b/dir.c
index 5aa6fba..d91295f 100644
--- a/dir.c
+++ b/dir.c
@@ -727,7 +727,7 @@
 	}
 
 	if (given->patternlen < 2 ||
-	    *given->pattern == '*' ||
+	    *given->pattern != '/' ||
 	    strstr(given->pattern, "**")) {
 		/* Not a cone pattern. */
 		warning(_("unrecognized pattern: '%s'"), given->pattern);
@@ -819,9 +819,7 @@
 		/* we already included this at the parent level */
 		warning(_("your sparse-checkout file may have issues: pattern '%s' is repeated"),
 			given->pattern);
-		hashmap_remove(&pl->parent_hashmap, &translated->ent, &data);
-		free(data);
-		free(translated);
+		goto clear_hashmaps;
 	}
 
 	return;
@@ -3160,6 +3158,7 @@
 	int ret = 0, original_len = path->len, len, kept_down = 0;
 	int only_empty = (flag & REMOVE_DIR_EMPTY_ONLY);
 	int keep_toplevel = (flag & REMOVE_DIR_KEEP_TOPLEVEL);
+	int purge_original_cwd = (flag & REMOVE_DIR_PURGE_ORIGINAL_CWD);
 	struct object_id submodule_head;
 
 	if ((flag & REMOVE_DIR_KEEP_NESTED_GIT) &&
@@ -3215,9 +3214,14 @@
 	closedir(dir);
 
 	strbuf_setlen(path, original_len);
-	if (!ret && !keep_toplevel && !kept_down)
-		ret = (!rmdir(path->buf) || errno == ENOENT) ? 0 : -1;
-	else if (kept_up)
+	if (!ret && !keep_toplevel && !kept_down) {
+		if (!purge_original_cwd &&
+		    startup_info->original_cwd &&
+		    !strcmp(startup_info->original_cwd, path->buf))
+			ret = -1; /* Do not remove current working directory */
+		else
+			ret = (!rmdir(path->buf) || errno == ENOENT) ? 0 : -1;
+	} else if (kept_up)
 		/*
 		 * report the uplevel that it is not an error that we
 		 * did not rmdir() our directory.
@@ -3283,6 +3287,9 @@
 		slash = dirs + (slash - name);
 		do {
 			*slash = '\0';
+			if (startup_info->original_cwd &&
+			    !strcmp(startup_info->original_cwd, dirs))
+				break;
 		} while (rmdir(dirs) == 0 && (slash = strrchr(dirs, '/')));
 		free(dirs);
 	}
diff --git a/dir.h b/dir.h
index 83f46c0..8e02dfb 100644
--- a/dir.h
+++ b/dir.h
@@ -495,6 +495,9 @@
 /* Remove the contents of path, but leave path itself. */
 #define REMOVE_DIR_KEEP_TOPLEVEL 04
 
+/* Remove the_original_cwd too */
+#define REMOVE_DIR_PURGE_ORIGINAL_CWD 0x08
+
 /*
  * Remove path and its contents, recursively. flags is a combination
  * of the above REMOVE_DIR_* constants. Return 0 on success.
@@ -504,7 +507,11 @@
  */
 int remove_dir_recursively(struct strbuf *path, int flag);
 
-/* tries to remove the path with empty directories along it, ignores ENOENT */
+/*
+ * Tries to remove the path, along with leading empty directories so long as
+ * those empty directories are not startup_info->original_cwd.  Ignores
+ * ENOENT.
+ */
 int remove_path(const char *path);
 
 int fspathcmp(const char *a, const char *b);
diff --git a/editor.c b/editor.c
index fdd3eea..8b96482 100644
--- a/editor.c
+++ b/editor.c
@@ -1,6 +1,7 @@
 #include "cache.h"
 #include "config.h"
 #include "strbuf.h"
+#include "strvec.h"
 #include "run-command.h"
 #include "sigchain.h"
 
@@ -55,7 +56,6 @@
 
 	if (strcmp(editor, ":")) {
 		struct strbuf realpath = STRBUF_INIT;
-		const char *args[] = { editor, NULL, NULL };
 		struct child_process p = CHILD_PROCESS_INIT;
 		int ret, sig;
 		int print_waiting_for_editor = advice_enabled(ADVICE_WAITING_FOR_EDITOR) && isatty(2);
@@ -77,10 +77,10 @@
 		}
 
 		strbuf_realpath(&realpath, path, 1);
-		args[1] = realpath.buf;
 
-		p.argv = args;
-		p.env = env;
+		strvec_pushl(&p.args, editor, realpath.buf, NULL);
+		if (env)
+			strvec_pushv(&p.env_array, (const char **)env);
 		p.use_shell = 1;
 		p.trace2_child_class = "editor";
 		if (start_command(&p) < 0) {
diff --git a/entry.c b/entry.c
index 9b0f968..1c9df62 100644
--- a/entry.c
+++ b/entry.c
@@ -82,11 +82,13 @@
 	return open(path, O_WRONLY | O_CREAT | O_EXCL, mode);
 }
 
-void *read_blob_entry(const struct cache_entry *ce, unsigned long *size)
+void *read_blob_entry(const struct cache_entry *ce, size_t *size)
 {
 	enum object_type type;
-	void *blob_data = read_object_file(&ce->oid, &type, size);
+	unsigned long ul;
+	void *blob_data = read_object_file(&ce->oid, &type, &ul);
 
+	*size = ul;
 	if (blob_data) {
 		if (type == OBJ_BLOB)
 			return blob_data;
@@ -271,7 +273,7 @@
 	int fd, ret, fstat_done = 0;
 	char *new_blob;
 	struct strbuf buf = STRBUF_INIT;
-	unsigned long size;
+	size_t size;
 	ssize_t wrote;
 	size_t newsize = 0;
 	struct stat st;
diff --git a/entry.h b/entry.h
index 2254c62..252fd24 100644
--- a/entry.h
+++ b/entry.h
@@ -52,7 +52,7 @@
  */
 void unlink_entry(const struct cache_entry *ce);
 
-void *read_blob_entry(const struct cache_entry *ce, unsigned long *size);
+void *read_blob_entry(const struct cache_entry *ce, size_t *size);
 int fstat_checkout_output(int fd, const struct checkout *state, struct stat *st);
 void update_ce_after_write(const struct checkout *state, struct cache_entry *ce,
 			   struct stat *st);
diff --git a/environment.c b/environment.c
index 9da7f3c..fd0501e 100644
--- a/environment.c
+++ b/environment.c
@@ -17,6 +17,7 @@
 #include "commit.h"
 #include "strvec.h"
 #include "object-store.h"
+#include "tmp-objdir.h"
 #include "chdir-notify.h"
 #include "shallow.h"
 
@@ -42,6 +43,7 @@
 int zlib_compression_level = Z_BEST_SPEED;
 int pack_compression_level = Z_DEFAULT_COMPRESSION;
 int fsync_object_files;
+int use_fsync = -1;
 size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE;
 size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT;
 size_t delta_base_cache_limit = 96 * 1024 * 1024;
@@ -168,6 +170,10 @@
 	args.graft_file = getenv_safe(&to_free, GRAFT_ENVIRONMENT);
 	args.index_file = getenv_safe(&to_free, INDEX_ENVIRONMENT);
 	args.alternate_db = getenv_safe(&to_free, ALTERNATE_DB_ENVIRONMENT);
+	if (getenv(GIT_QUARANTINE_ENVIRONMENT)) {
+		args.disable_ref_updates = 1;
+	}
+
 	repo_set_gitdir(the_repository, git_dir, &args);
 	strvec_clear(&to_free);
 
@@ -331,10 +337,14 @@
 				   void *data)
 {
 	char *path = reparent_relative_path(old_cwd, new_cwd, get_git_dir());
+	struct tmp_objdir *tmp_objdir = tmp_objdir_unapply_primary_odb();
+
 	trace_printf_key(&trace_setup_key,
 			 "setup: move $GIT_DIR to '%s'",
 			 path);
 	set_git_dir_1(path);
+	if (tmp_objdir)
+		tmp_objdir_reapply_primary_odb(tmp_objdir, old_cwd, new_cwd);
 	free(path);
 }
 
diff --git a/fetch-pack.c b/fetch-pack.c
index a9604f3..dd6ec44 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -25,6 +25,7 @@
 #include "shallow.h"
 #include "commit-reach.h"
 #include "commit-graph.h"
+#include "sigchain.h"
 
 static int transfer_unpack_limit = -1;
 static int fetch_unpack_limit = -1;
@@ -296,7 +297,7 @@
 	struct packet_reader reader;
 
 	if (args->stateless_rpc && multi_ack == 1)
-		die(_("--stateless-rpc requires multi_ack_detailed"));
+		die(_("the option '%s' requires '%s'"), "--stateless-rpc", "multi_ack_detailed");
 
 	packet_reader_init(&reader, fd[0], NULL, 0,
 			   PACKET_READ_CHOMP_NEWLINE |
@@ -956,6 +957,8 @@
 			strvec_push(index_pack_args, cmd.args.v[i]);
 	}
 
+	sigchain_push(SIGPIPE, SIG_IGN);
+
 	cmd.in = demux.out;
 	cmd.git_cmd = 1;
 	if (start_command(&cmd))
@@ -986,6 +989,8 @@
 	if (use_sideband && finish_async(&demux))
 		die(_("error in sideband demultiplexer"));
 
+	sigchain_pop(SIGPIPE);
+
 	/*
 	 * Now that index-pack has succeeded, write the promisor file using the
 	 * obtained .keep filename if necessary
@@ -1653,8 +1658,13 @@
 				receive_wanted_refs(&reader, sought, nr_sought);
 
 			/* get the pack(s) */
+			if (git_env_bool("GIT_TRACE_REDACT", 1))
+				reader.options |= PACKET_READ_REDACT_URI_PATH;
 			if (process_section_header(&reader, "packfile-uris", 1))
 				receive_packfile_uris(&reader, &packfile_uris);
+			/* We don't expect more URIs. Reset to avoid expensive URI check. */
+			reader.options &= ~PACKET_READ_REDACT_URI_PATH;
+
 			process_section_header(&reader, "packfile", 0);
 
 			/*
diff --git a/fmt-merge-msg.c b/fmt-merge-msg.c
index 5216191..baca57d 100644
--- a/fmt-merge-msg.c
+++ b/fmt-merge-msg.c
@@ -533,14 +533,14 @@
 		else {
 			buf = payload.buf;
 			len = payload.len;
-			if (check_signature(payload.buf, payload.len, sig.buf,
-					    sig.len, &sigc) &&
+			sigc.payload_type = SIGNATURE_PAYLOAD_TAG;
+			sigc.payload = strbuf_detach(&payload, &sigc.payload_len);
+			if (check_signature(&sigc, sig.buf, sig.len) &&
 			    !sigc.output)
 				strbuf_addstr(&sig, "gpg verification failed.\n");
 			else
 				strbuf_addstr(&sig, sigc.output);
 		}
-		signature_check_clear(&sigc);
 
 		if (!tag_number++) {
 			fmt_tag_signature(&tagbuf, &sig, buf, len);
@@ -564,6 +564,7 @@
 		}
 		strbuf_release(&payload);
 		strbuf_release(&sig);
+		signature_check_clear(&sigc);
 	next:
 		free(origbuf);
 	}
@@ -649,12 +650,15 @@
 
 	memset(&merge_parents, 0, sizeof(merge_parents));
 
-	/* get current branch */
+	/* learn the commit that we merge into and the current branch name */
 	current_branch = current_branch_to_free =
 		resolve_refdup("HEAD", RESOLVE_REF_READING, &head_oid, NULL);
 	if (!current_branch)
 		die("No current branch");
-	if (starts_with(current_branch, "refs/heads/"))
+
+	if (opts->into_name)
+		current_branch = opts->into_name;
+	else if (starts_with(current_branch, "refs/heads/"))
 		current_branch += 11;
 
 	find_merge_parents(&merge_parents, in, &head_oid);
diff --git a/fmt-merge-msg.h b/fmt-merge-msg.h
index f2ab0e0..9905404 100644
--- a/fmt-merge-msg.h
+++ b/fmt-merge-msg.h
@@ -9,6 +9,7 @@
 	unsigned add_title:1,
 		credit_people:1;
 	int shortlog_len;
+	const char *into_name;
 };
 
 extern int merge_log_config;
diff --git a/generate-cmdlist.sh b/generate-cmdlist.sh
index 9dbbb08..205541e 100755
--- a/generate-cmdlist.sh
+++ b/generate-cmdlist.sh
@@ -6,37 +6,38 @@
 }
 
 command_list () {
-	eval "grep -ve '^#' $exclude_programs" <"$1"
-}
-
-get_categories () {
-	tr ' ' '\012'|
-	grep -v '^$' |
-	sort |
-	uniq
+	while read cmd rest
+	do
+		case "$cmd" in
+		"#"* | '')
+			# Ignore comments and allow empty lines
+			continue
+			;;
+		*)
+			case "$exclude_programs" in
+			*":$cmd:"*)
+				;;
+			*)
+				echo "$cmd $rest"
+				;;
+			esac
+		esac
+	done <"$1"
 }
 
 category_list () {
-	command_list "$1" |
-	cut -c 40- |
-	get_categories
-}
-
-get_synopsis () {
-	sed -n '
-		/^NAME/,/'"$1"'/H
-		${
-			x
-			s/.*'"$1"' - \(.*\)/N_("\1")/
-			p
-		}' "Documentation/$1.txt"
+	echo "$1" |
+	cut -d' ' -f2- |
+	tr ' ' '\012' |
+	grep -v '^$' |
+	LC_ALL=C sort -u
 }
 
 define_categories () {
 	echo
 	echo "/* Command categories */"
 	bit=0
-	category_list "$1" |
+	echo "$1" |
 	while read cat
 	do
 		echo "#define CAT_$cat (1UL << $bit)"
@@ -50,7 +51,7 @@
 	echo "/* Category names */"
 	echo "static const char *category_names[] = {"
 	bit=0
-	category_list "$1" |
+	echo "$1" |
 	while read cat
 	do
 		echo "	\"$cat\", /* (1UL << $bit) */"
@@ -63,27 +64,38 @@
 print_command_list () {
 	echo "static struct cmdname_help command_list[] = {"
 
-	command_list "$1" |
+	echo "$1" |
 	while read cmd rest
 	do
-		printf "	{ \"$cmd\", $(get_synopsis $cmd), 0"
-		for cat in $(echo "$rest" | get_categories)
+		synopsis=
+		while read line
 		do
-			printf " | CAT_$cat"
-		done
+			case "$line" in
+			"$cmd - "*)
+				synopsis=${line#$cmd - }
+				break
+				;;
+			esac
+		done <"Documentation/$cmd.txt"
+
+		printf '\t{ "%s", N_("%s"), 0' "$cmd" "$synopsis"
+		printf " | CAT_%s" $rest
 		echo " },"
 	done
 	echo "};"
 }
 
-exclude_programs=
+exclude_programs=:
 while test "--exclude-program" = "$1"
 do
 	shift
-	exclude_programs="$exclude_programs -e \"^$1 \""
+	exclude_programs="$exclude_programs$1:"
 	shift
 done
 
+commands="$(command_list "$1")"
+categories="$(category_list "$commands")"
+
 echo "/* Automatically generated by generate-cmdlist.sh */
 struct cmdname_help {
 	const char *name;
@@ -91,8 +103,8 @@
 	uint32_t category;
 };
 "
-define_categories "$1"
+define_categories "$categories"
 echo
-define_category_names "$1"
+define_category_names "$categories"
 echo
-print_command_list "$1"
+print_command_list "$commands"
diff --git a/git-add--interactive.perl b/git-add--interactive.perl
index bc3a1e8..95887fd 100755
--- a/git-add--interactive.perl
+++ b/git-add--interactive.perl
@@ -1175,15 +1175,17 @@
 		ReadMode 'cbreak';
 		my $key = ReadKey 0;
 		ReadMode 'restore';
-		if ($use_termcap and $key eq "\e") {
-			while (!defined $term_escapes{$key}) {
-				my $next = ReadKey 0.5;
-				last if (!defined $next);
-				$key .= $next;
+		if (defined $key) {
+			if ($use_termcap and $key eq "\e") {
+				while (!defined $term_escapes{$key}) {
+					my $next = ReadKey 0.5;
+					last if (!defined $next);
+					$key .= $next;
+				}
+				$key =~ s/\e/^[/;
 			}
-			$key =~ s/\e/^[/;
+			print "$key";
 		}
-		print "$key" if defined $key;
 		print "\n";
 		return $key;
 	} else {
diff --git a/git-compat-util.h b/git-compat-util.h
index d70ce14..1229c82 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1,6 +1,19 @@
 #ifndef GIT_COMPAT_UTIL_H
 #define GIT_COMPAT_UTIL_H
 
+#if __STDC_VERSION__ - 0 < 199901L
+/*
+ * Git is in a testing period for mandatory C99 support in the compiler.  If
+ * your compiler is reasonably recent, you can try to enable C99 support (or,
+ * for MSVC, C11 support).  If you encounter a problem and can't enable C99
+ * support with your compiler (such as with "-std=gnu99") and don't have access
+ * to one with this support, such as GCC or Clang, you can remove this #if
+ * directive, but please report the details of your system to
+ * git@vger.kernel.org.
+ */
+#error "Required C99 support is in a test phase.  Please see git-compat-util.h for more details."
+#endif
+
 #ifdef USE_MSVC_CRTDBG
 /*
  * For these to work they must appear very early in each
@@ -33,14 +46,23 @@
 /*
  * See if our compiler is known to support flexible array members.
  */
-#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) && (!defined(__SUNPRO_C) || (__SUNPRO_C > 0x580))
-# define FLEX_ARRAY /* empty */
+
+/*
+ * Check vendor specific quirks first, before checking the
+ * __STDC_VERSION__, as vendor compilers can lie and we need to be
+ * able to work them around.  Note that by not defining FLEX_ARRAY
+ * here, we can fall back to use the "safer but a bit wasteful" one
+ * later.
+ */
+#if defined(__SUNPRO_C) && (__SUNPRO_C <= 0x580)
 #elif defined(__GNUC__)
 # if (__GNUC__ >= 3)
 #  define FLEX_ARRAY /* empty */
 # else
 #  define FLEX_ARRAY 0 /* older GNU extension */
 # endif
+#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
+# define FLEX_ARRAY /* empty */
 #endif
 
 /*
@@ -113,6 +135,14 @@
 #define unsigned_mult_overflows(a, b) \
     ((a) && (b) > maximum_unsigned_value_of_type(a) / (a))
 
+/*
+ * Returns true if the left shift of "a" by "shift" bits will
+ * overflow. The type of "a" must be unsigned.
+ */
+#define unsigned_left_shift_overflows(a, shift) \
+    ((shift) < bitsizeof(a) && \
+     (a) > maximum_unsigned_value_of_type(a) >> (shift))
+
 #ifdef __GNUC__
 #define TYPEOF(x) (__typeof__(x))
 #else
@@ -127,7 +157,9 @@
 /* Approximation of the length of the decimal representation of this type. */
 #define decimal_length(x)	((int)(sizeof(x) * 2.56 + 0.5) + 1)
 
-#if defined(__sun__)
+#ifdef __MINGW64__
+#define _POSIX_C_SOURCE 1
+#elif defined(__sun__)
  /*
   * On Solaris, when _XOPEN_EXTENDED is set, its header file
   * forces the programs to be XPG4v2, defeating any _XOPEN_SOURCE
@@ -466,11 +498,12 @@
 struct strbuf;
 
 /* General helper functions */
-void vreportf(const char *prefix, const char *err, va_list params);
 NORETURN void usage(const char *err);
 NORETURN void usagef(const char *err, ...) __attribute__((format (printf, 1, 2)));
 NORETURN void die(const char *err, ...) __attribute__((format (printf, 1, 2)));
 NORETURN void die_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
+int die_message(const char *err, ...) __attribute__((format (printf, 1, 2)));
+int die_message_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
 int error(const char *err, ...) __attribute__((format (printf, 1, 2)));
 int error_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
 void warning(const char *err, ...) __attribute__((format (printf, 1, 2)));
@@ -505,6 +538,7 @@
 typedef void (*report_fn)(const char *, va_list params);
 
 void set_die_routine(NORETURN_PTR report_fn routine);
+report_fn get_die_message_routine(void);
 void set_error_routine(report_fn routine);
 report_fn get_error_routine(void);
 void set_warn_routine(report_fn routine);
@@ -729,7 +763,7 @@
 
 #ifdef NO_UNSETENV
 #define unsetenv gitunsetenv
-void gitunsetenv(const char *);
+int gitunsetenv(const char *);
 #endif
 
 #ifdef NO_STRCASESTR
@@ -862,6 +896,23 @@
 	return a - b;
 }
 
+static inline size_t st_left_shift(size_t a, unsigned shift)
+{
+	if (unsigned_left_shift_overflows(a, shift))
+		die("size_t overflow: %"PRIuMAX" << %u",
+		    (uintmax_t)a, shift);
+	return a << shift;
+}
+
+static inline unsigned long cast_size_t_to_ulong(size_t a)
+{
+	if (a != (unsigned long)a)
+		die("object too large to read on this platform: %"
+		    PRIuMAX" is cut off to %lu",
+		    (uintmax_t)a, (unsigned long)a);
+	return (unsigned long)a;
+}
+
 #ifdef HAVE_ALLOCA_H
 # include <alloca.h>
 # define xalloca(size)      (alloca(size))
diff --git a/git-cvsserver.perl b/git-cvsserver.perl
index 64319be..4c81180 100755
--- a/git-cvsserver.perl
+++ b/git-cvsserver.perl
@@ -3607,6 +3607,22 @@
 use strict;
 use warnings;
 use DBI;
+our $_use_fsync;
+
+# n.b. consider using Git.pm
+sub use_fsync {
+    if (!defined($_use_fsync)) {
+        my $x = $ENV{GIT_TEST_FSYNC};
+        if (defined $x) {
+            local $ENV{GIT_CONFIG};
+            delete $ENV{GIT_CONFIG};
+            my $v = ::safe_pipe_capture('git', '-c', "test.fsync=$x",
+                                        qw(config --type=bool test.fsync));
+            $_use_fsync = defined($v) ? ($v eq "true\n") : 1;
+        }
+    }
+    $_use_fsync;
+}
 
 =head1 METHODS
 
@@ -3676,6 +3692,9 @@
                                 $self->{dbuser},
                                 $self->{dbpass});
     die "Error connecting to database\n" unless defined $self->{dbh};
+    if ($self->{dbdriver} eq 'SQLite' && !use_fsync()) {
+        $self->{dbh}->do('PRAGMA synchronous = OFF');
+    }
 
     $self->{tables} = {};
     foreach my $table ( keys %{$self->{dbh}->table_info(undef,undef,undef,'TABLE')->fetchall_hashref('TABLE_NAME')} )
diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index cb89372..3a51d45 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -579,7 +579,7 @@
 				git hash-object -t tag -w --stdin) ||
 				die "Could not create new tag object for $ref"
 			if git cat-file tag "$ref" | \
-			   sane_grep '^-----BEGIN PGP SIGNATURE-----' >/dev/null 2>&1
+			   grep '^-----BEGIN PGP SIGNATURE-----' >/dev/null 2>&1
 			then
 				warn "gpg signature stripped from tag object $sha1t"
 			fi
diff --git a/git-instaweb.sh b/git-instaweb.sh
index 7c55229..4349566 100755
--- a/git-instaweb.sh
+++ b/git-instaweb.sh
@@ -49,7 +49,7 @@
 	*apache2*|*lighttpd*|*httpd*)
 		# yes, *httpd* covers *lighttpd* above, but it is there for clarity
 		# ensure that the apache2/lighttpd command ends with "-f"
-		if ! echo "$httpd" | sane_grep -- '-f *$' >/dev/null 2>&1
+		if ! echo "$httpd" | grep -- '-f *$' >/dev/null 2>&1
 		then
 			httpd="$httpd -f"
 		fi
@@ -380,10 +380,7 @@
 DirectoryIndex gitweb.cgi
 EOF
 
-	# check to see if Dennis Stosberg's mod_perl compatibility patch
-	# (<20060621130708.Gcbc6e5c@leonov.stosberg.net>) has been applied
-	if test -f "$module_path/mod_perl.so" &&
-	   sane_grep 'MOD_PERL' "$root/gitweb.cgi" >/dev/null
+	if test -f "$module_path/mod_perl.so"
 	then
 		# favor mod_perl if available
 		cat >> "$conf" <<EOF
@@ -402,7 +399,7 @@
 		# plain-old CGI
 		resolve_full_httpd
 		list_mods=$(echo "$full_httpd" | sed 's/-f$/-l/')
-		$list_mods | sane_grep 'mod_cgi\.c' >/dev/null 2>&1 || \
+		$list_mods | grep 'mod_cgi\.c' >/dev/null 2>&1 || \
 		if test -f "$module_path/mod_cgi.so"
 		then
 			echo "LoadModule cgi_module $module_path/mod_cgi.so" >> "$conf"
diff --git a/git-p4.py b/git-p4.py
index 2b45002..cb37545 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -56,6 +56,21 @@
 
 p4_access_checked = False
 
+re_ko_keywords = re.compile(br'\$(Id|Header)(:[^$\n]+)?\$')
+re_k_keywords = re.compile(br'\$(Id|Header|Author|Date|DateTime|Change|File|Revision)(:[^$\n]+)?\$')
+
+def format_size_human_readable(num):
+    """ Returns a number of units (typically bytes) formatted as a human-readable
+        string.
+    """
+    if num < 1024:
+        return '{:d} B'.format(num)
+    for unit in ["Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi"]:
+        num /= 1024.0
+        if num < 1024.0:
+            return "{:3.1f} {}B".format(num, unit)
+    return "{:.1f} YiB".format(num)
+
 def p4_build_cmd(cmd):
     """Build a suitable p4 command line.
 
@@ -337,17 +352,19 @@
     real_cmd = p4_build_cmd(c)
     return read_pipe(real_cmd, ignore_error, raw=raw)
 
-def read_pipe_lines(c):
+def read_pipe_lines(c, raw=False):
     if verbose:
         sys.stderr.write('Reading pipe: %s\n' % str(c))
 
     expand = not isinstance(c, list)
     p = subprocess.Popen(c, stdout=subprocess.PIPE, shell=expand)
     pipe = p.stdout
-    val = [decode_text_stream(line) for line in pipe.readlines()]
+    lines = pipe.readlines()
+    if not raw:
+        lines = [decode_text_stream(line) for line in lines]
     if pipe.close() or p.wait():
         die('Command failed: %s' % str(c))
-    return val
+    return lines
 
 def p4_read_pipe_lines(c):
     """Specifically invoke p4 on the command supplied. """
@@ -577,20 +594,12 @@
 #
 def p4_keywords_regexp_for_type(base, type_mods):
     if base in ("text", "unicode", "binary"):
-        kwords = None
         if "ko" in type_mods:
-            kwords = 'Id|Header'
+            return re_ko_keywords
         elif "k" in type_mods:
-            kwords = 'Id|Header|Author|Date|DateTime|Change|File|Revision'
+            return re_k_keywords
         else:
             return None
-        pattern = r"""
-            \$              # Starts with a dollar, followed by...
-            (%s)            # one of the keywords, followed by...
-            (:[^$\n]+)?     # possibly an old expansion, followed by...
-            \$              # another dollar
-            """ % kwords
-        return pattern
     else:
         return None
 
@@ -1532,80 +1541,6 @@
         except IOError:
             self.getUserMapFromPerforceServer()
 
-class P4Debug(Command):
-    def __init__(self):
-        Command.__init__(self)
-        self.options = []
-        self.description = "A tool to debug the output of p4 -G."
-        self.needsGit = False
-
-    def run(self, args):
-        j = 0
-        for output in p4CmdList(args):
-            print('Element: %d' % j)
-            j += 1
-            print(output)
-        return True
-
-class P4RollBack(Command):
-    def __init__(self):
-        Command.__init__(self)
-        self.options = [
-            optparse.make_option("--local", dest="rollbackLocalBranches", action="store_true")
-        ]
-        self.description = "A tool to debug the multi-branch import. Don't use :)"
-        self.rollbackLocalBranches = False
-
-    def run(self, args):
-        if len(args) != 1:
-            return False
-        maxChange = int(args[0])
-
-        if "p4ExitCode" in p4Cmd("changes -m 1"):
-            die("Problems executing p4");
-
-        if self.rollbackLocalBranches:
-            refPrefix = "refs/heads/"
-            lines = read_pipe_lines("git rev-parse --symbolic --branches")
-        else:
-            refPrefix = "refs/remotes/"
-            lines = read_pipe_lines("git rev-parse --symbolic --remotes")
-
-        for line in lines:
-            if self.rollbackLocalBranches or (line.startswith("p4/") and line != "p4/HEAD\n"):
-                line = line.strip()
-                ref = refPrefix + line
-                log = extractLogMessageFromGitCommit(ref)
-                settings = extractSettingsGitLog(log)
-
-                depotPaths = settings['depot-paths']
-                change = settings['change']
-
-                changed = False
-
-                if len(p4Cmd("changes -m 1 "  + ' '.join (['%s...@%s' % (p, maxChange)
-                                                           for p in depotPaths]))) == 0:
-                    print("Branch %s did not exist at change %s, deleting." % (ref, maxChange))
-                    system("git update-ref -d %s `git rev-parse %s`" % (ref, ref))
-                    continue
-
-                while change and int(change) > maxChange:
-                    changed = True
-                    if self.verbose:
-                        print("%s is at %s ; rewinding towards %s" % (ref, change, maxChange))
-                    system("git update-ref %s \"%s^\"" % (ref, ref))
-                    log = extractLogMessageFromGitCommit(ref)
-                    settings =  extractSettingsGitLog(log)
-
-
-                    depotPaths = settings['depot-paths']
-                    change = settings['change']
-
-                if changed:
-                    print("%s rewound to %s" % (ref, change))
-
-        return True
-
 class P4Submit(Command, P4UserMap):
 
     conflict_behavior_choices = ("ask", "skip", "quit")
@@ -1753,18 +1688,13 @@
 
         return result
 
-    def patchRCSKeywords(self, file, pattern):
-        # Attempt to zap the RCS keywords in a p4 controlled file matching the given pattern
+    def patchRCSKeywords(self, file, regexp):
+        # Attempt to zap the RCS keywords in a p4 controlled file matching the given regex
         (handle, outFileName) = tempfile.mkstemp(dir='.')
         try:
-            outFile = os.fdopen(handle, "w+")
-            inFile = open(file, "r")
-            regexp = re.compile(pattern, re.VERBOSE)
-            for line in inFile.readlines():
-                line = regexp.sub(r'$\1$', line)
-                outFile.write(line)
-            inFile.close()
-            outFile.close()
+            with os.fdopen(handle, "wb") as outFile, open(file, "rb") as inFile:
+                for line in inFile.readlines():
+                    outFile.write(regexp.sub(br'$\1$', line))
             # Forcibly overwrite the original file
             os.unlink(file)
             shutil.move(outFileName, file)
@@ -2091,25 +2021,24 @@
             # the patch to see if that's possible.
             if gitConfigBool("git-p4.attemptRCSCleanup"):
                 file = None
-                pattern = None
                 kwfiles = {}
                 for file in editedFiles | filesToDelete:
                     # did this file's delta contain RCS keywords?
-                    pattern = p4_keywords_regexp_for_file(file)
-
-                    if pattern:
+                    regexp = p4_keywords_regexp_for_file(file)
+                    if regexp:
                         # this file is a possibility...look for RCS keywords.
-                        regexp = re.compile(pattern, re.VERBOSE)
-                        for line in read_pipe_lines(["git", "diff", "%s^..%s" % (id, id), file]):
+                        for line in read_pipe_lines(
+                            ["git", "diff", "%s^..%s" % (id, id), file],
+                            raw=True):
                             if regexp.search(line):
                                 if verbose:
-                                    print("got keyword match on %s in %s in %s" % (pattern, line, file))
-                                kwfiles[file] = pattern
+                                    print("got keyword match on %s in %s in %s" % (regex.pattern, line, file))
+                                kwfiles[file] = regexp
                                 break
 
-                for file in kwfiles:
+                for file, regexp in kwfiles.items():
                     if verbose:
-                        print("zapping %s with %s" % (line,pattern))
+                        print("zapping %s with %s" % (line, regexp.pattern))
                     # File is being deleted, so not open in p4.  Must
                     # disable the read-only bit on windows.
                     if self.isWindows and file not in editedFiles:
@@ -2966,7 +2895,8 @@
                 size = int(self.stream_file['fileSize'])
             else:
                 size = 0 # deleted files don't get a fileSize apparently
-            sys.stdout.write('\r%s --> %s (%i MB)\n' % (file_path, relPath, size/1024/1024))
+            sys.stdout.write('\r%s --> %s (%s)\n' % (
+                file_path, relPath, format_size_human_readable(size)))
             sys.stdout.flush()
 
         (type_base, type_mods) = split_p4_type(file["type"])
@@ -3029,12 +2959,9 @@
 
         # Note that we do not try to de-mangle keywords on utf16 files,
         # even though in theory somebody may want that.
-        pattern = p4_keywords_regexp_for_type(type_base, type_mods)
-        if pattern:
-            regexp = re.compile(pattern, re.VERBOSE)
-            text = ''.join(decode_text_stream(c) for c in contents)
-            text = regexp.sub(r'$\1$', text)
-            contents = [ encode_text_stream(text) ]
+        regexp = p4_keywords_regexp_for_type(type_base, type_mods)
+        if regexp:
+            contents = [regexp.sub(br'$\1$', c) for c in contents]
 
         if self.largeFileSystem:
             (git_mode, contents) = self.largeFileSystem.processContent(git_mode, relPath, contents)
@@ -3064,9 +2991,8 @@
         if not err and 'fileSize' in self.stream_file:
             required_bytes = int((4 * int(self.stream_file["fileSize"])) - calcDiskFree())
             if required_bytes > 0:
-                err = 'Not enough space left on %s! Free at least %i MB.' % (
-                    os.getcwd(), required_bytes/1024/1024
-                )
+                err = 'Not enough space left on %s! Free at least %s.' % (
+                    os.getcwd(), format_size_human_readable(required_bytes))
 
         if err:
             f = None
@@ -3110,7 +3036,9 @@
             size = int(self.stream_file["fileSize"])
             if size > 0:
                 progress = 100*self.stream_file['streamContentSize']/size
-                sys.stdout.write('\r%s %d%% (%i MB)' % (self.stream_file['depotFile'], progress, int(size/1024/1024)))
+                sys.stdout.write('\r%s %d%% (%s)' % (
+                    self.stream_file['depotFile'], progress,
+                    format_size_human_readable(size)))
                 sys.stdout.flush()
 
         self.stream_have_file_info = True
@@ -3623,7 +3551,8 @@
             self.updateOptionDict(description)
 
             if not self.silent:
-                sys.stdout.write("\rImporting revision %s (%s%%)" % (change, cnt * 100 / len(changes)))
+                sys.stdout.write("\rImporting revision %s (%d%%)" % (
+                    change, (cnt * 100) // len(changes)))
                 sys.stdout.flush()
             cnt = cnt + 1
 
@@ -4363,13 +4292,11 @@
     print("")
 
 commands = {
-    "debug" : P4Debug,
     "submit" : P4Submit,
     "commit" : P4Submit,
     "sync" : P4Sync,
     "rebase" : P4Rebase,
     "clone" : P4Clone,
-    "rollback" : P4RollBack,
     "branches" : P4Branches,
     "unshelve" : P4Unshelve,
 }
diff --git a/git-send-email.perl b/git-send-email.perl
index 5262d88..0408722 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -40,7 +40,8 @@
 
 sub usage {
 	print <<EOT;
-git send-email [options] <file | directory | rev-list options >
+git send-email' [<options>] <file|directory>
+git send-email' [<options>] <format-patch options>
 git send-email --dump-aliases
 
   Composing:
@@ -113,9 +114,38 @@
 	exit(1);
 }
 
+sub uniq {
+	my %seen;
+	grep !$seen{$_}++, @_;
+}
+
 sub completion_helper {
-    print Git::command('format-patch', '--git-completion-helper');
-    exit(0);
+	my ($original_opts) = @_;
+	my %not_for_completion = (
+		"git-completion-helper" => undef,
+		"h" => undef,
+	);
+	my @send_email_opts = ();
+
+	foreach my $key (keys %$original_opts) {
+		unless (exists $not_for_completion{$key}) {
+			$key =~ s/!$//;
+
+			if ($key =~ /[:=][si]$/) {
+				$key =~ s/[:=][si]$//;
+				push (@send_email_opts, "--$_=") foreach (split (/\|/, $key));
+			} else {
+				push (@send_email_opts, "--$_") foreach (split (/\|/, $key));
+			}
+		}
+	}
+
+	my @format_patch_opts = split(/ /, Git::command('format-patch', '--git-completion-helper'));
+	my @opts = (@send_email_opts, @format_patch_opts);
+	@opts = uniq (grep !/^$/, @opts);
+	# There's an implicit '\n' here already, no need to add an explicit one.
+	print "@opts";
+	exit(0);
 }
 
 # most mail servers generate the Date: header, but not all...
@@ -425,10 +455,11 @@
 	my $key = "sendemail.identity";
 	$identity = Git::config(@repo, $key) if exists $known_config_keys{$key};
 }
-my $rc = GetOptions(
+my %identity_options = (
 	"identity=s" => \$identity,
 	"no-identity" => \$no_identity,
 );
+my $rc = GetOptions(%identity_options);
 usage() unless $rc;
 undef $identity if $no_identity;
 
@@ -444,14 +475,17 @@
 
 my $help;
 my $git_completion_helper;
-$rc = GetOptions("h" => \$help,
-                 "dump-aliases" => \$dump_aliases);
+my %dump_aliases_options = (
+	"h" => \$help,
+	"dump-aliases" => \$dump_aliases,
+);
+$rc = GetOptions(%dump_aliases_options);
 usage() unless $rc;
 die __("--dump-aliases incompatible with other options\n")
     if !$help and $dump_aliases and @ARGV;
-$rc = GetOptions(
+my %options = (
 		    "sender|from=s" => \$sender,
-                    "in-reply-to=s" => \$initial_in_reply_to,
+		    "in-reply-to=s" => \$initial_in_reply_to,
 		    "reply-to=s" => \$reply_to,
 		    "subject=s" => \$initial_subject,
 		    "to=s" => \@getopt_to,
@@ -508,7 +542,8 @@
 		    "batch-size=i" => \$batch_size,
 		    "relogin-delay=i" => \$relogin_delay,
 		    "git-completion-helper" => \$git_completion_helper,
-	 );
+);
+$rc = GetOptions(%options);
 
 # Munge any "either config or getopt, not both" variables
 my @initial_to = @getopt_to ? @getopt_to : ($no_to ? () : @config_to);
@@ -516,7 +551,8 @@
 my @initial_bcc = @getopt_bcc ? @getopt_bcc : ($no_bcc ? () : @config_bcc);
 
 usage() if $help;
-completion_helper() if $git_completion_helper;
+my %all_options = (%options, %dump_aliases_options, %identity_options);
+completion_helper(\%all_options) if $git_completion_helper;
 unless ($rc) {
     usage();
 }
diff --git a/git-sh-setup.sh b/git-sh-setup.sh
index 960982f..b93f392 100644
--- a/git-sh-setup.sh
+++ b/git-sh-setup.sh
@@ -173,14 +173,6 @@
 	eval "$GIT_PAGER" '"$@"'
 }
 
-sane_grep () {
-	GREP_OPTIONS= LC_ALL=C grep @@SANE_TEXT_GREP@@ "$@"
-}
-
-sane_egrep () {
-	GREP_OPTIONS= LC_ALL=C egrep @@SANE_TEXT_GREP@@ "$@"
-}
-
 is_bare_repository () {
 	git rev-parse --is-bare-repository
 }
diff --git a/git.c b/git.c
index 5ff21be..edda922 100644
--- a/git.c
+++ b/git.c
@@ -185,7 +185,7 @@
 				*envchanged = 1;
 		} else if (!strcmp(cmd, "--git-dir")) {
 			if (*argc < 2) {
-				fprintf(stderr, _("no directory given for --git-dir\n" ));
+				fprintf(stderr, _("no directory given for '%s' option\n" ), "--git-dir");
 				usage(git_usage_string);
 			}
 			setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
@@ -213,7 +213,7 @@
 				*envchanged = 1;
 		} else if (!strcmp(cmd, "--work-tree")) {
 			if (*argc < 2) {
-				fprintf(stderr, _("no directory given for --work-tree\n" ));
+				fprintf(stderr, _("no directory given for '%s' option\n" ), "--work-tree");
 				usage(git_usage_string);
 			}
 			setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
@@ -297,7 +297,7 @@
 				*envchanged = 1;
 		} else if (!strcmp(cmd, "-C")) {
 			if (*argc < 2) {
-				fprintf(stderr, _("no directory given for -C\n" ));
+				fprintf(stderr, _("no directory given for '%s' option\n" ), "-C");
 				usage(git_usage_string);
 			}
 			if ((*argv)[1][0]) {
@@ -421,27 +421,30 @@
 	int status, help;
 	struct stat st;
 	const char *prefix;
+	int run_setup = (p->option & (RUN_SETUP | RUN_SETUP_GENTLY));
 
-	prefix = NULL;
 	help = argc == 2 && !strcmp(argv[1], "-h");
-	if (!help) {
-		if (p->option & RUN_SETUP)
-			prefix = setup_git_directory();
-		else if (p->option & RUN_SETUP_GENTLY) {
-			int nongit_ok;
-			prefix = setup_git_directory_gently(&nongit_ok);
-		}
-		precompose_argv_prefix(argc, argv, NULL);
-		if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY) &&
-		    !(p->option & DELAY_PAGER_CONFIG))
-			use_pager = check_pager_config(p->cmd);
-		if (use_pager == -1 && p->option & USE_PAGER)
-			use_pager = 1;
+	if (help && (run_setup & RUN_SETUP))
+		/* demote to GENTLY to allow 'git cmd -h' outside repo */
+		run_setup = RUN_SETUP_GENTLY;
 
-		if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
-		    startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
-			trace_repo_setup(prefix);
+	if (run_setup & RUN_SETUP) {
+		prefix = setup_git_directory();
+	} else if (run_setup & RUN_SETUP_GENTLY) {
+		int nongit_ok;
+		prefix = setup_git_directory_gently(&nongit_ok);
+	} else {
+		prefix = NULL;
 	}
+	precompose_argv_prefix(argc, argv, NULL);
+	if (use_pager == -1 && run_setup &&
+		!(p->option & DELAY_PAGER_CONFIG))
+		use_pager = check_pager_config(p->cmd);
+	if (use_pager == -1 && p->option & USE_PAGER)
+		use_pager = 1;
+	if (run_setup && startup_info->have_repository)
+		/* get_git_dir() may set up repo, avoid that */
+		trace_repo_setup(prefix);
 	commit_pager_choice();
 
 	if (!help && get_super_prefix()) {
diff --git a/gpg-interface.c b/gpg-interface.c
index 3e7255a..b52eb0e 100644
--- a/gpg-interface.c
+++ b/gpg-interface.c
@@ -19,8 +19,8 @@
 	const char **verify_args;
 	const char **sigs;
 	int (*verify_signed_buffer)(struct signature_check *sigc,
-				    struct gpg_format *fmt, const char *payload,
-				    size_t payload_size, const char *signature,
+				    struct gpg_format *fmt,
+				    const char *signature,
 				    size_t signature_size);
 	int (*sign_buffer)(struct strbuf *buffer, struct strbuf *signature,
 			   const char *signing_key);
@@ -53,12 +53,12 @@
 };
 
 static int verify_gpg_signed_buffer(struct signature_check *sigc,
-				    struct gpg_format *fmt, const char *payload,
-				    size_t payload_size, const char *signature,
+				    struct gpg_format *fmt,
+				    const char *signature,
 				    size_t signature_size);
 static int verify_ssh_signed_buffer(struct signature_check *sigc,
-				    struct gpg_format *fmt, const char *payload,
-				    size_t payload_size, const char *signature,
+				    struct gpg_format *fmt,
+				    const char *signature,
 				    size_t signature_size);
 static int sign_buffer_gpg(struct strbuf *buffer, struct strbuf *signature,
 			   const char *signing_key);
@@ -314,8 +314,8 @@
 }
 
 static int verify_gpg_signed_buffer(struct signature_check *sigc,
-				    struct gpg_format *fmt, const char *payload,
-				    size_t payload_size, const char *signature,
+				    struct gpg_format *fmt,
+				    const char *signature,
 				    size_t signature_size)
 {
 	struct child_process gpg = CHILD_PROCESS_INIT;
@@ -343,14 +343,13 @@
 		     NULL);
 
 	sigchain_push(SIGPIPE, SIG_IGN);
-	ret = pipe_command(&gpg, payload, payload_size, &gpg_stdout, 0,
+	ret = pipe_command(&gpg, sigc->payload, sigc->payload_len, &gpg_stdout, 0,
 			   &gpg_stderr, 0);
 	sigchain_pop(SIGPIPE);
 
 	delete_tempfile(&temp);
 
 	ret |= !strstr(gpg_stdout.buf, "\n[GNUPG:] GOODSIG ");
-	sigc->payload = xmemdupz(payload, payload_size);
 	sigc->output = strbuf_detach(&gpg_stderr, NULL);
 	sigc->gpg_status = strbuf_detach(&gpg_stdout, NULL);
 
@@ -426,8 +425,8 @@
 }
 
 static int verify_ssh_signed_buffer(struct signature_check *sigc,
-				    struct gpg_format *fmt, const char *payload,
-				    size_t payload_size, const char *signature,
+				    struct gpg_format *fmt,
+				    const char *signature,
 				    size_t signature_size)
 {
 	struct child_process ssh_keygen = CHILD_PROCESS_INIT;
@@ -440,6 +439,13 @@
 	struct strbuf ssh_principals_err = STRBUF_INIT;
 	struct strbuf ssh_keygen_out = STRBUF_INIT;
 	struct strbuf ssh_keygen_err = STRBUF_INIT;
+	struct strbuf verify_time = STRBUF_INIT;
+	const struct date_mode verify_date_mode = {
+		.type = DATE_STRFTIME,
+		.strftime_fmt = "%Y%m%d%H%M%S",
+		/* SSH signing key validity has no timezone information - Use the local timezone */
+		.local = 1,
+	};
 
 	if (!ssh_allowed_signers) {
 		error(_("gpg.ssh.allowedSignersFile needs to be configured and exist for ssh signature verification"));
@@ -457,11 +463,16 @@
 		return -1;
 	}
 
+	if (sigc->payload_timestamp)
+		strbuf_addf(&verify_time, "-Overify-time=%s",
+			show_date(sigc->payload_timestamp, 0, &verify_date_mode));
+
 	/* Find the principal from the signers */
 	strvec_pushl(&ssh_keygen.args, fmt->program,
 		     "-Y", "find-principals",
 		     "-f", ssh_allowed_signers,
 		     "-s", buffer_file->filename.buf,
+		     verify_time.buf,
 		     NULL);
 	ret = pipe_command(&ssh_keygen, NULL, 0, &ssh_principals_out, 0,
 			   &ssh_principals_err, 0);
@@ -479,8 +490,9 @@
 			     "-Y", "check-novalidate",
 			     "-n", "git",
 			     "-s", buffer_file->filename.buf,
+			     verify_time.buf,
 			     NULL);
-		pipe_command(&ssh_keygen, payload, payload_size,
+		pipe_command(&ssh_keygen, sigc->payload, sigc->payload_len,
 				   &ssh_keygen_out, 0, &ssh_keygen_err, 0);
 
 		/*
@@ -513,6 +525,7 @@
 				     "-f", ssh_allowed_signers,
 				     "-I", principal,
 				     "-s", buffer_file->filename.buf,
+				     verify_time.buf,
 				     NULL);
 
 			if (ssh_revocation_file) {
@@ -526,7 +539,7 @@
 			}
 
 			sigchain_push(SIGPIPE, SIG_IGN);
-			ret = pipe_command(&ssh_keygen, payload, payload_size,
+			ret = pipe_command(&ssh_keygen, sigc->payload, sigc->payload_len,
 					   &ssh_keygen_out, 0, &ssh_keygen_err, 0);
 			sigchain_pop(SIGPIPE);
 
@@ -540,7 +553,6 @@
 		}
 	}
 
-	sigc->payload = xmemdupz(payload, payload_size);
 	strbuf_stripspace(&ssh_keygen_out, 0);
 	strbuf_stripspace(&ssh_keygen_err, 0);
 	/* Add stderr outputs to show the user actual ssh-keygen errors */
@@ -558,12 +570,48 @@
 	strbuf_release(&ssh_principals_err);
 	strbuf_release(&ssh_keygen_out);
 	strbuf_release(&ssh_keygen_err);
+	strbuf_release(&verify_time);
 
 	return ret;
 }
 
-int check_signature(const char *payload, size_t plen, const char *signature,
-	size_t slen, struct signature_check *sigc)
+static int parse_payload_metadata(struct signature_check *sigc)
+{
+	const char *ident_line = NULL;
+	size_t ident_len;
+	struct ident_split ident;
+	const char *signer_header;
+
+	switch (sigc->payload_type) {
+	case SIGNATURE_PAYLOAD_COMMIT:
+		signer_header = "committer";
+		break;
+	case SIGNATURE_PAYLOAD_TAG:
+		signer_header = "tagger";
+		break;
+	case SIGNATURE_PAYLOAD_UNDEFINED:
+	case SIGNATURE_PAYLOAD_PUSH_CERT:
+		/* Ignore payloads we don't want to parse */
+		return 0;
+	default:
+		BUG("invalid value for sigc->payload_type");
+	}
+
+	ident_line = find_commit_header(sigc->payload, signer_header, &ident_len);
+	if (!ident_line || !ident_len)
+		return 1;
+
+	if (split_ident_line(&ident, ident_line, ident_len))
+		return 1;
+
+	if (!sigc->payload_timestamp && ident.date_begin && ident.date_end)
+		sigc->payload_timestamp = parse_timestamp(ident.date_begin, NULL, 10);
+
+	return 0;
+}
+
+int check_signature(struct signature_check *sigc,
+		    const char *signature, size_t slen)
 {
 	struct gpg_format *fmt;
 	int status;
@@ -575,8 +623,10 @@
 	if (!fmt)
 		die(_("bad/incompatible signature '%s'"), signature);
 
-	status = fmt->verify_signed_buffer(sigc, fmt, payload, plen, signature,
-					   slen);
+	if (parse_payload_metadata(sigc))
+		return 1;
+
+	status = fmt->verify_signed_buffer(sigc, fmt, signature, slen);
 
 	if (status && !sigc->output)
 		return !!status;
@@ -593,7 +643,7 @@
 							    sigc->output;
 
 	if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
-		fputs(sigc->payload, stdout);
+		fwrite(sigc->payload, 1, sigc->payload_len, stdout);
 
 	if (output)
 		fputs(output, stderr);
@@ -707,6 +757,21 @@
 	return 0;
 }
 
+/*
+ * Returns 1 if `string` contains a literal ssh key, 0 otherwise
+ * `key` will be set to the start of the actual key if a prefix is present.
+ */
+static int is_literal_ssh_key(const char *string, const char **key)
+{
+	if (skip_prefix(string, "key::", key))
+		return 1;
+	if (starts_with(string, "ssh-")) {
+		*key = string;
+		return 1;
+	}
+	return 0;
+}
+
 static char *get_ssh_key_fingerprint(const char *signing_key)
 {
 	struct child_process ssh_keygen = CHILD_PROCESS_INIT;
@@ -714,15 +779,16 @@
 	struct strbuf fingerprint_stdout = STRBUF_INIT;
 	struct strbuf **fingerprint;
 	char *fingerprint_ret;
+	const char *literal_key = NULL;
 
 	/*
 	 * With SSH Signing this can contain a filename or a public key
 	 * For textual representation we usually want a fingerprint
 	 */
-	if (starts_with(signing_key, "ssh-")) {
+	if (is_literal_ssh_key(signing_key, &literal_key)) {
 		strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf", "-", NULL);
-		ret = pipe_command(&ssh_keygen, signing_key,
-				   strlen(signing_key), &fingerprint_stdout, 0,
+		ret = pipe_command(&ssh_keygen, literal_key,
+				   strlen(literal_key), &fingerprint_stdout, 0,
 				   NULL, 0);
 	} else {
 		strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf",
@@ -757,6 +823,7 @@
 	const char **argv;
 	int n;
 	char *default_key = NULL;
+	const char *literal_key = NULL;
 
 	if (!ssh_default_key_command)
 		die(_("either user.signingkey or gpg.ssh.defaultKeyCommand needs to be configured"));
@@ -774,7 +841,11 @@
 
 	if (!ret) {
 		keys = strbuf_split_max(&key_stdout, '\n', 2);
-		if (keys[0] && starts_with(keys[0]->buf, "ssh-")) {
+		if (keys[0] && is_literal_ssh_key(keys[0]->buf, &literal_key)) {
+			/*
+			 * We only use `is_literal_ssh_key` here to check validity
+			 * The prefix will be stripped when the key is used.
+			 */
 			default_key = strbuf_detach(keys[0], NULL);
 		} else {
 			warning(_("gpg.ssh.defaultKeyCommand succeeded but returned no keys: %s %s"),
@@ -889,19 +960,20 @@
 	struct tempfile *key_file = NULL, *buffer_file = NULL;
 	char *ssh_signing_key_file = NULL;
 	struct strbuf ssh_signature_filename = STRBUF_INIT;
+	const char *literal_key = NULL;
 
 	if (!signing_key || signing_key[0] == '\0')
 		return error(
 			_("user.signingkey needs to be set for ssh signing"));
 
-	if (starts_with(signing_key, "ssh-")) {
+	if (is_literal_ssh_key(signing_key, &literal_key)) {
 		/* A literal ssh key */
 		key_file = mks_tempfile_t(".git_signing_key_tmpXXXXXX");
 		if (!key_file)
 			return error_errno(
 				_("could not create temporary file"));
-		keylen = strlen(signing_key);
-		if (write_in_full(key_file->fd, signing_key, keylen) < 0 ||
+		keylen = strlen(literal_key);
+		if (write_in_full(key_file->fd, literal_key, keylen) < 0 ||
 		    close_tempfile_gently(key_file) < 0) {
 			error_errno(_("failed writing ssh signing key to '%s'"),
 				    key_file->filename.buf);
diff --git a/gpg-interface.h b/gpg-interface.h
index beefacb..b30cbdc 100644
--- a/gpg-interface.h
+++ b/gpg-interface.h
@@ -15,8 +15,18 @@
 	TRUST_ULTIMATE,
 };
 
+enum payload_type {
+	SIGNATURE_PAYLOAD_UNDEFINED,
+	SIGNATURE_PAYLOAD_COMMIT,
+	SIGNATURE_PAYLOAD_TAG,
+	SIGNATURE_PAYLOAD_PUSH_CERT,
+};
+
 struct signature_check {
 	char *payload;
+	size_t payload_len;
+	enum payload_type payload_type;
+	timestamp_t payload_timestamp;
 	char *output;
 	char *gpg_status;
 
@@ -70,9 +80,8 @@
  * Either a GPG KeyID or a SSH Key Fingerprint
  */
 const char *get_signing_key_id(void);
-int check_signature(const char *payload, size_t plen,
-		    const char *signature, size_t slen,
-		    struct signature_check *sigc);
+int check_signature(struct signature_check *sigc,
+		    const char *signature, size_t slen);
 void print_signature_buffer(const struct signature_check *sigc,
 			    unsigned flags);
 
diff --git a/grep.c b/grep.c
index fe847a0..7bb0360 100644
--- a/grep.c
+++ b/grep.c
@@ -26,10 +26,10 @@
 	.pattern_type_option = GREP_PATTERN_TYPE_UNSPECIFIED,
 	.colors = {
 		[GREP_COLOR_CONTEXT] = "",
-		[GREP_COLOR_FILENAME] = "",
+		[GREP_COLOR_FILENAME] = GIT_COLOR_MAGENTA,
 		[GREP_COLOR_FUNCTION] = "",
-		[GREP_COLOR_LINENO] = "",
-		[GREP_COLOR_COLUMNNO] = "",
+		[GREP_COLOR_LINENO] = GIT_COLOR_GREEN,
+		[GREP_COLOR_COLUMNNO] = GIT_COLOR_GREEN,
 		[GREP_COLOR_MATCH_CONTEXT] = GIT_COLOR_BOLD_RED,
 		[GREP_COLOR_MATCH_SELECTED] = GIT_COLOR_BOLD_RED,
 		[GREP_COLOR_SELECTED] = "",
@@ -362,6 +362,7 @@
 	int jitret;
 	int patinforet;
 	size_t jitsizearg;
+	int literal = !opt->ignore_case && (p->fixed || p->is_fixed);
 
 	/*
 	 * Call pcre2_general_context_create() before calling any
@@ -382,8 +383,7 @@
 		}
 		options |= PCRE2_CASELESS;
 	}
-	if (!opt->ignore_locale && is_utf8_locale() && has_non_ascii(p->pattern) &&
-	    !(!opt->ignore_case && (p->fixed || p->is_fixed)))
+	if (!opt->ignore_locale && is_utf8_locale() && !literal)
 		options |= (PCRE2_UTF | PCRE2_MATCH_INVALID_UTF);
 
 #ifdef GIT_PCRE2_VERSION_10_36_OR_HIGHER
@@ -699,6 +699,14 @@
 	return compile_pattern_or(list);
 }
 
+static struct grep_expr *grep_not_expr(struct grep_expr *expr)
+{
+	struct grep_expr *z = xcalloc(1, sizeof(*z));
+	z->node = GREP_NODE_NOT;
+	z->u.unary = expr;
+	return z;
+}
+
 static struct grep_expr *grep_true_expr(void)
 {
 	struct grep_expr *z = xcalloc(1, sizeof(*z));
@@ -797,7 +805,7 @@
 		}
 	}
 
-	if (opt->all_match || header_expr)
+	if (opt->all_match || opt->no_body_match || header_expr)
 		opt->extended = 1;
 	else if (!opt->extended)
 		return;
@@ -808,6 +816,9 @@
 	if (p)
 		die("incomplete pattern expression: %s", p->pattern);
 
+	if (opt->no_body_match && opt->pattern_expression)
+		opt->pattern_expression = grep_not_expr(opt->pattern_expression);
+
 	if (!header_expr)
 		return;
 
@@ -1057,6 +1068,8 @@
 			if (h && (*col < 0 || tmp.rm_so < *col))
 				*col = tmp.rm_so;
 		}
+		if (x->u.atom->token == GREP_PATTERN_BODY)
+			opt->body_hit |= h;
 		break;
 	case GREP_NODE_NOT:
 		/*
@@ -1825,16 +1838,19 @@
 	 * we do not have to do the two-pass grep when we do not check
 	 * buffer-wide "all-match".
 	 */
-	if (!opt->all_match)
+	if (!opt->all_match && !opt->no_body_match)
 		return grep_source_1(opt, gs, 0);
 
 	/* Otherwise the toplevel "or" terms hit a bit differently.
 	 * We first clear hit markers from them.
 	 */
 	clr_hit_marker(opt->pattern_expression);
+	opt->body_hit = 0;
 	grep_source_1(opt, gs, 1);
 
-	if (!chk_hit_marker(opt->pattern_expression))
+	if (opt->all_match && !chk_hit_marker(opt->pattern_expression))
+		return 0;
+	if (opt->no_body_match && opt->body_hit)
 		return 0;
 
 	return grep_source_1(opt, gs, 0);
diff --git a/grep.h b/grep.h
index 3e8815c..6a1f0ab 100644
--- a/grep.h
+++ b/grep.h
@@ -148,6 +148,8 @@
 	int word_regexp;
 	int fixed;
 	int all_match;
+	int no_body_match;
+	int body_hit;
 #define GREP_BINARY_DEFAULT	0
 #define GREP_BINARY_NOMATCH	1
 #define GREP_BINARY_TEXT	2
diff --git a/hash.h b/hash.h
index 9e25c40..5d40368 100644
--- a/hash.h
+++ b/hash.h
@@ -95,12 +95,18 @@
 /* Number of algorithms supported (including unknown). */
 #define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1)
 
+/* "sha1", big-endian */
+#define GIT_SHA1_FORMAT_ID 0x73686131
+
 /* The length in bytes and in hex digits of an object name (SHA-1 value). */
 #define GIT_SHA1_RAWSZ 20
 #define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
 /* The block size of SHA-1. */
 #define GIT_SHA1_BLKSZ 64
 
+/* "s256", big-endian */
+#define GIT_SHA256_FORMAT_ID 0x73323536
+
 /* The length in bytes and in hex digits of an object name (SHA-256 value). */
 #define GIT_SHA256_RAWSZ 32
 #define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)
diff --git a/help.c b/help.c
index 973e47c..7144490 100644
--- a/help.c
+++ b/help.c
@@ -643,7 +643,7 @@
 		else if (autocorrect == AUTOCORRECT_PROMPT) {
 			char *answer;
 			struct strbuf msg = STRBUF_INIT;
-			strbuf_addf(&msg, _("Run '%s' instead? (y/N)"), assumed);
+			strbuf_addf(&msg, _("Run '%s' instead [y/N]? "), assumed);
 			answer = git_prompt(msg.buf, PROMPT_ECHO);
 			strbuf_release(&msg);
 			if (!(starts_with(answer, "y") ||
diff --git a/http-backend.c b/http-backend.c
index 3d6e2ff..807fb88 100644
--- a/http-backend.c
+++ b/http-backend.c
@@ -480,7 +480,7 @@
 		strvec_pushf(&cld.env_array,
 			     "GIT_COMMITTER_EMAIL=%s@http.%s", user, host);
 
-	cld.argv = argv;
+	strvec_pushv(&cld.args, argv);
 	if (buffer_input || gzipped_request || req_len >= 0)
 		cld.in = -1;
 	cld.git_cmd = 1;
@@ -659,8 +659,9 @@
 {
 	if (dead <= 1) {
 		struct strbuf hdr = STRBUF_INIT;
+		report_fn die_message_fn = get_die_message_routine();
 
-		vreportf("fatal: ", err, params);
+		die_message_fn(err, params);
 
 		http_status(&hdr, 500, "Internal Server Error");
 		hdr_nocache(&hdr);
diff --git a/http-fetch.c b/http-fetch.c
index fa64246..58b394c 100644
--- a/http-fetch.c
+++ b/http-fetch.c
@@ -4,6 +4,7 @@
 #include "http.h"
 #include "walker.h"
 #include "strvec.h"
+#include "urlmatch.h"
 
 static const char http_fetch_usage[] = "git http-fetch "
 "[-c] [-t] [-a] [-v] [--recover] [-w ref] [--stdin | --packfile=hash | commit-id] url";
@@ -63,8 +64,17 @@
 	if (start_active_slot(preq->slot)) {
 		run_active_slot(preq->slot);
 		if (results.curl_result != CURLE_OK) {
-			die("Unable to get pack file %s\n%s", preq->url,
-			    curl_errorstr);
+			struct url_info url;
+			char *nurl = url_normalize(preq->url, &url);
+			if (!nurl || !git_env_bool("GIT_TRACE_REDACT", 1)) {
+				die("unable to get pack file '%s'\n%s", preq->url,
+				    curl_errorstr);
+			} else {
+				die("failed to get '%.*s' url from '%.*s' "
+				    "(full URL redacted due to GIT_TRACE_REDACT setting)\n%s",
+				    (int)url.scheme_len, url.url,
+				    (int)url.host_len, &url.url[url.host_off], curl_errorstr);
+			}
 		}
 	} else {
 		die("Unable to start request");
@@ -131,7 +141,7 @@
 
 	if (packfile) {
 		if (!index_pack_args.nr)
-			die(_("--packfile requires --index-pack-args"));
+			die(_("the option '%s' requires '%s'"), "--packfile", "--index-pack-args");
 
 		fetch_single_packfile(&packfile_hash, argv[arg],
 				      index_pack_args.v);
@@ -140,7 +150,7 @@
 	}
 
 	if (index_pack_args.nr)
-		die(_("--index-pack-args can only be used with --packfile"));
+		die(_("the option '%s' requires '%s'"), "--index-pack-args", "--packfile");
 
 	if (commits_on_stdin) {
 		commits = walker_targets_stdin(&commit_id, &write_ref);
diff --git a/http.c b/http.c
index f92859f..229da4d 100644
--- a/http.c
+++ b/http.c
@@ -2126,8 +2126,9 @@
 
 	ip.git_cmd = 1;
 	ip.in = tmpfile_fd;
-	ip.argv = preq->index_pack_args ? preq->index_pack_args
-					: default_index_pack_args;
+	strvec_pushv(&ip.args, preq->index_pack_args ?
+		     preq->index_pack_args :
+		     default_index_pack_args);
 
 	if (preq->preserve_index_pack_stdout)
 		ip.out = 0;
diff --git a/log-tree.c b/log-tree.c
index 644893f..d3e7a40 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -513,8 +513,9 @@
 	if (parse_signed_commit(commit, &payload, &signature, the_hash_algo) <= 0)
 		goto out;
 
-	status = check_signature(payload.buf, payload.len, signature.buf,
-				 signature.len, &sigc);
+	sigc.payload_type = SIGNATURE_PAYLOAD_COMMIT;
+	sigc.payload = strbuf_detach(&payload, &sigc.payload_len);
+	status = check_signature(&sigc, signature.buf, signature.len);
 	if (status && !sigc.output)
 		show_sig_lines(opt, status, "No signature\n");
 	else
@@ -583,8 +584,9 @@
 	status = -1;
 	if (parse_signature(extra->value, extra->len, &payload, &signature)) {
 		/* could have a good signature */
-		status = check_signature(payload.buf, payload.len,
-					 signature.buf, signature.len, &sigc);
+		sigc.payload_type = SIGNATURE_PAYLOAD_TAG;
+		sigc.payload = strbuf_detach(&payload, &sigc.payload_len);
+		status = check_signature(&sigc, signature.buf, signature.len);
 		if (sigc.output)
 			strbuf_addstr(&verify_message, sigc.output);
 		else
diff --git a/merge-ort.c b/merge-ort.c
index 0342f10..c319797 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -3841,9 +3841,22 @@
 		if (opt->renormalize &&
 		    blob_unchanged(opt, &ci->stages[0], &ci->stages[side],
 				   path)) {
-			ci->merged.is_null = 1;
-			ci->merged.clean = 1;
-			assert(!ci->df_conflict && !ci->path_conflict);
+			if (!ci->path_conflict) {
+				/*
+				 * Blob unchanged after renormalization, so
+				 * there's no modify/delete conflict after all;
+				 * we can just remove the file.
+				 */
+				ci->merged.is_null = 1;
+				ci->merged.clean = 1;
+				 /*
+				  * file goes away => even if there was a
+				  * directory/file conflict there isn't one now.
+				  */
+				ci->df_conflict = 0;
+			} else {
+				/* rename/delete, so conflict remains */
+			}
 		} else if (ci->path_conflict &&
 			   oideq(&ci->stages[0].oid, &ci->stages[side].oid)) {
 			/*
diff --git a/mergesort.c b/mergesort.c
index 6216835..bd9c6ef 100644
--- a/mergesort.c
+++ b/mergesort.c
@@ -63,7 +63,7 @@
 		void *next = get_next_fn(list);
 		if (next)
 			set_next_fn(list, NULL);
-		for (i = 0; n & (1 << i); i++)
+		for (i = 0; n & ((size_t)1 << i); i++)
 			list = llist_merge(ranks[i], list, get_next_fn,
 					   set_next_fn, compare_fn);
 		n++;
diff --git a/midx.c b/midx.c
index 8433086..837b46b 100644
--- a/midx.c
+++ b/midx.c
@@ -57,15 +57,15 @@
 	return m->data + m->data_len - the_hash_algo->rawsz;
 }
 
-char *get_midx_filename(const char *object_dir)
+void get_midx_filename(struct strbuf *out, const char *object_dir)
 {
-	return xstrfmt("%s/pack/multi-pack-index", object_dir);
+	strbuf_addf(out, "%s/pack/multi-pack-index", object_dir);
 }
 
-char *get_midx_rev_filename(struct multi_pack_index *m)
+void get_midx_rev_filename(struct strbuf *out, struct multi_pack_index *m)
 {
-	return xstrfmt("%s/pack/multi-pack-index-%s.rev",
-		       m->object_dir, hash_to_hex(get_midx_checksum(m)));
+	get_midx_filename(out, m->object_dir);
+	strbuf_addf(out, "-%s.rev", hash_to_hex(get_midx_checksum(m)));
 }
 
 static int midx_read_oid_fanout(const unsigned char *chunk_start,
@@ -89,28 +89,30 @@
 	size_t midx_size;
 	void *midx_map = NULL;
 	uint32_t hash_version;
-	char *midx_name = get_midx_filename(object_dir);
+	struct strbuf midx_name = STRBUF_INIT;
 	uint32_t i;
 	const char *cur_pack_name;
 	struct chunkfile *cf = NULL;
 
-	fd = git_open(midx_name);
+	get_midx_filename(&midx_name, object_dir);
+
+	fd = git_open(midx_name.buf);
 
 	if (fd < 0)
 		goto cleanup_fail;
 	if (fstat(fd, &st)) {
-		error_errno(_("failed to read %s"), midx_name);
+		error_errno(_("failed to read %s"), midx_name.buf);
 		goto cleanup_fail;
 	}
 
 	midx_size = xsize_t(st.st_size);
 
 	if (midx_size < MIDX_MIN_SIZE) {
-		error(_("multi-pack-index file %s is too small"), midx_name);
+		error(_("multi-pack-index file %s is too small"), midx_name.buf);
 		goto cleanup_fail;
 	}
 
-	FREE_AND_NULL(midx_name);
+	strbuf_release(&midx_name);
 
 	midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 	close(fd);
@@ -179,12 +181,13 @@
 	trace2_data_intmax("midx", the_repository, "load/num_packs", m->num_packs);
 	trace2_data_intmax("midx", the_repository, "load/num_objects", m->num_objects);
 
+	free_chunkfile(cf);
 	return m;
 
 cleanup_fail:
 	free(m);
-	free(midx_name);
-	free(cf);
+	strbuf_release(&midx_name);
+	free_chunkfile(cf);
 	if (midx_map)
 		munmap(midx_map, midx_size);
 	if (0 <= fd)
@@ -1130,7 +1133,7 @@
 			       const char *refs_snapshot,
 			       unsigned flags)
 {
-	char *midx_name;
+	struct strbuf midx_name = STRBUF_INIT;
 	unsigned char midx_hash[GIT_MAX_RAWSZ];
 	uint32_t i;
 	struct hashfile *f = NULL;
@@ -1141,10 +1144,10 @@
 	int result = 0;
 	struct chunkfile *cf;
 
-	midx_name = get_midx_filename(object_dir);
-	if (safe_create_leading_directories(midx_name))
+	get_midx_filename(&midx_name, object_dir);
+	if (safe_create_leading_directories(midx_name.buf))
 		die_errno(_("unable to create leading directories of %s"),
-			  midx_name);
+			  midx_name.buf);
 
 	if (!packs_to_include) {
 		/*
@@ -1373,7 +1376,7 @@
 		pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
 					(pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
 
-	hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
+	hold_lock_file_for_update(&lk, midx_name.buf, LOCK_DIE_ON_ERROR);
 	f = hashfd(get_lock_file_fd(&lk), get_lock_file_path(&lk));
 
 	if (ctx.nr - dropped_packs == 0) {
@@ -1410,9 +1413,9 @@
 		ctx.pack_order = midx_pack_order(&ctx);
 
 	if (flags & MIDX_WRITE_REV_INDEX)
-		write_midx_reverse_index(midx_name, midx_hash, &ctx);
+		write_midx_reverse_index(midx_name.buf, midx_hash, &ctx);
 	if (flags & MIDX_WRITE_BITMAP) {
-		if (write_midx_bitmap(midx_name, midx_hash, &ctx,
+		if (write_midx_bitmap(midx_name.buf, midx_hash, &ctx,
 				      refs_snapshot, flags) < 0) {
 			error(_("could not write multi-pack bitmap"));
 			result = 1;
@@ -1442,7 +1445,7 @@
 	free(ctx.entries);
 	free(ctx.pack_perm);
 	free(ctx.pack_order);
-	free(midx_name);
+	strbuf_release(&midx_name);
 
 	return result;
 }
@@ -1506,20 +1509,22 @@
 
 void clear_midx_file(struct repository *r)
 {
-	char *midx = get_midx_filename(r->objects->odb->path);
+	struct strbuf midx = STRBUF_INIT;
+
+	get_midx_filename(&midx, r->objects->odb->path);
 
 	if (r->objects && r->objects->multi_pack_index) {
 		close_midx(r->objects->multi_pack_index);
 		r->objects->multi_pack_index = NULL;
 	}
 
-	if (remove_path(midx))
-		die(_("failed to clear multi-pack-index at %s"), midx);
+	if (remove_path(midx.buf))
+		die(_("failed to clear multi-pack-index at %s"), midx.buf);
 
 	clear_midx_files_ext(r->objects->odb->path, ".bitmap", NULL);
 	clear_midx_files_ext(r->objects->odb->path, ".rev", NULL);
 
-	free(midx);
+	strbuf_release(&midx);
 }
 
 static int verify_midx_error;
@@ -1572,12 +1577,15 @@
 	if (!m) {
 		int result = 0;
 		struct stat sb;
-		char *filename = get_midx_filename(object_dir);
-		if (!stat(filename, &sb)) {
+		struct strbuf filename = STRBUF_INIT;
+
+		get_midx_filename(&filename, object_dir);
+
+		if (!stat(filename.buf, &sb)) {
 			error(_("multi-pack-index file exists, but failed to parse"));
 			result = 1;
 		}
-		free(filename);
+		strbuf_release(&filename);
 		return result;
 	}
 
@@ -1610,7 +1618,7 @@
 		 * Remaining tests assume that we have objects, so we can
 		 * return here.
 		 */
-		return verify_midx_error;
+		goto cleanup;
 	}
 
 	if (flags & MIDX_PROGRESS)
@@ -1688,7 +1696,9 @@
 	}
 	stop_progress(&progress);
 
+cleanup:
 	free(pairs);
+	close_midx(m);
 
 	return verify_midx_error;
 }
diff --git a/midx.h b/midx.h
index 6e32297..b7d79a5 100644
--- a/midx.h
+++ b/midx.h
@@ -48,8 +48,8 @@
 #define MIDX_WRITE_BITMAP_HASH_CACHE (1 << 3)
 
 const unsigned char *get_midx_checksum(struct multi_pack_index *m);
-char *get_midx_filename(const char *object_dir);
-char *get_midx_rev_filename(struct multi_pack_index *m);
+void get_midx_filename(struct strbuf *out, const char *object_dir);
+void get_midx_rev_filename(struct strbuf *out, struct multi_pack_index *m);
 
 struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local);
 int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t pack_int_id);
diff --git a/object-file.c b/object-file.c
index c3d866a..8be57f4 100644
--- a/object-file.c
+++ b/object-file.c
@@ -165,7 +165,6 @@
 	BUG("trying to finalize unknown hash");
 }
 
-
 const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
 	{
 		NULL,
@@ -184,8 +183,7 @@
 	},
 	{
 		"sha1",
-		/* "sha1", big-endian */
-		0x73686131,
+		GIT_SHA1_FORMAT_ID,
 		GIT_SHA1_RAWSZ,
 		GIT_SHA1_HEXSZ,
 		GIT_SHA1_BLKSZ,
@@ -200,8 +198,7 @@
 	},
 	{
 		"sha256",
-		/* "s256", big-endian */
-		0x73323536,
+		GIT_SHA256_FORMAT_ID,
 		GIT_SHA256_RAWSZ,
 		GIT_SHA256_HEXSZ,
 		GIT_SHA256_BLKSZ,
@@ -683,6 +680,49 @@
 			     '\n', NULL, 0);
 }
 
+struct object_directory *set_temporary_primary_odb(const char *dir, int will_destroy)
+{
+	struct object_directory *new_odb;
+
+	/*
+	 * Make sure alternates are initialized, or else our entry may be
+	 * overwritten when they are.
+	 */
+	prepare_alt_odb(the_repository);
+
+	/*
+	 * Make a new primary odb and link the old primary ODB in as an
+	 * alternate
+	 */
+	new_odb = xcalloc(1, sizeof(*new_odb));
+	new_odb->path = xstrdup(dir);
+
+	/*
+	 * Disable ref updates while a temporary odb is active, since
+	 * the objects in the database may roll back.
+	 */
+	new_odb->disable_ref_updates = 1;
+	new_odb->will_destroy = will_destroy;
+	new_odb->next = the_repository->objects->odb;
+	the_repository->objects->odb = new_odb;
+	return new_odb->next;
+}
+
+void restore_primary_odb(struct object_directory *restore_odb, const char *old_path)
+{
+	struct object_directory *cur_odb = the_repository->objects->odb;
+
+	if (strcmp(old_path, cur_odb->path))
+		BUG("expected %s as primary object store; found %s",
+		    old_path, cur_odb->path);
+
+	if (cur_odb->next != restore_odb)
+		BUG("we expect the old primary object store to be the first alternate");
+
+	the_repository->objects->odb = restore_odb;
+	free_object_directory(cur_odb);
+}
+
 /*
  * Compute the exact path an alternate is at and returns it. In case of
  * error NULL is returned and the human readable error is added to `err`
@@ -797,7 +837,7 @@
 		}
 	}
 
-	cmd->env = local_repo_env;
+	strvec_pushv(&cmd->env_array, (const char **)local_repo_env);
 	cmd->out = -1;
 }
 
@@ -1306,7 +1346,7 @@
 int parse_loose_header(const char *hdr, struct object_info *oi)
 {
 	const char *type_buf = hdr;
-	unsigned long size;
+	size_t size;
 	int type, type_len = 0;
 
 	/*
@@ -1341,12 +1381,12 @@
 			if (c > 9)
 				break;
 			hdr++;
-			size = size * 10 + c;
+			size = st_add(st_mult(size, 10), c);
 		}
 	}
 
 	if (oi->sizep)
-		*oi->sizep = size;
+		*oi->sizep = cast_size_t_to_ulong(size);
 
 	/*
 	 * The length must be followed by a zero byte
@@ -1809,8 +1849,11 @@
 /* Finalize a file on disk, and close it. */
 static void close_loose_object(int fd)
 {
-	if (fsync_object_files)
-		fsync_or_die(fd, "loose object file");
+	if (!the_repository->objects->odb->will_destroy) {
+		if (fsync_object_files)
+			fsync_or_die(fd, "loose object file");
+	}
+
 	if (close(fd) != 0)
 		die_errno(_("error when closing loose object file"));
 }
@@ -2425,7 +2468,7 @@
 	struct strbuf buf = STRBUF_INIT;
 	size_t word_bits = bitsizeof(odb->loose_objects_subdir_seen[0]);
 	size_t word_index = subdir_nr / word_bits;
-	size_t mask = 1u << (subdir_nr % word_bits);
+	size_t mask = (size_t)1u << (subdir_nr % word_bits);
 	uint32_t *bitmap;
 
 	if (subdir_nr < 0 ||
diff --git a/object-store.h b/object-store.h
index 952efb6..6f89482 100644
--- a/object-store.h
+++ b/object-store.h
@@ -28,6 +28,18 @@
 	struct oidtree *loose_objects_cache;
 
 	/*
+	 * This is a temporary object store created by the tmp_objdir
+	 * facility. Disable ref updates since the objects in the store
+	 * might be discarded on rollback.
+	 */
+	int disable_ref_updates;
+
+	/*
+	 * This object store is ephemeral, so there is no need to fsync.
+	 */
+	int will_destroy;
+
+	/*
 	 * Path to the alternative object store. If this is a relative path,
 	 * it is relative to the current working directory.
 	 */
@@ -59,6 +71,17 @@
 void add_to_alternates_memory(const char *dir);
 
 /*
+ * Replace the current writable object directory with the specified temporary
+ * object directory; returns the former primary object directory.
+ */
+struct object_directory *set_temporary_primary_odb(const char *dir, int will_destroy);
+
+/*
+ * Restore a previous ODB replaced by set_temporary_main_odb.
+ */
+void restore_primary_odb(struct object_directory *restore_odb, const char *old_path);
+
+/*
  * Populate and return the loose object cache array corresponding to the
  * given object ID.
  */
@@ -68,6 +91,9 @@
 /* Empty the loose object cache for the specified object directory. */
 void odb_clear_loose_cache(struct object_directory *odb);
 
+/* Clear and free the specified object directory */
+void free_object_directory(struct object_directory *odb);
+
 struct packed_git {
 	struct hashmap_entry packmap_ent;
 	struct packed_git *next;
diff --git a/object.c b/object.c
index 23a24e6..c37501f 100644
--- a/object.c
+++ b/object.c
@@ -199,7 +199,7 @@
 	case OBJ_BLOB:
 		return (struct object *)lookup_blob(r, oid);
 	default:
-		die("BUG: unknown object type %d", type);
+		BUG("unknown object type %d", type);
 	}
 }
 
@@ -513,7 +513,7 @@
 	return o;
 }
 
-static void free_object_directory(struct object_directory *odb)
+void free_object_directory(struct object_directory *odb)
 {
 	free(odb->path);
 	odb_clear_loose_cache(odb);
diff --git a/pack-bitmap.c b/pack-bitmap.c
index f47a0a7..f772d3c 100644
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -292,9 +292,12 @@
 
 char *midx_bitmap_filename(struct multi_pack_index *midx)
 {
-	return xstrfmt("%s-%s.bitmap",
-		       get_midx_filename(midx->object_dir),
-		       hash_to_hex(get_midx_checksum(midx)));
+	struct strbuf buf = STRBUF_INIT;
+
+	get_midx_filename(&buf, midx->object_dir);
+	strbuf_addf(&buf, "-%s.bitmap", hash_to_hex(get_midx_checksum(midx)));
+
+	return strbuf_detach(&buf, NULL);
 }
 
 char *pack_bitmap_filename(struct packed_git *p)
@@ -324,10 +327,12 @@
 	}
 
 	if (bitmap_git->pack || bitmap_git->midx) {
+		struct strbuf buf = STRBUF_INIT;
+		get_midx_filename(&buf, midx->object_dir);
 		/* ignore extra bitmap file; we can only handle one */
-		warning("ignoring extra bitmap file: %s",
-			get_midx_filename(midx->object_dir));
+		warning("ignoring extra bitmap file: %s", buf.buf);
 		close(fd);
+		strbuf_release(&buf);
 		return -1;
 	}
 
@@ -1721,6 +1726,12 @@
 	else
 		die("mismatch in bitmap results");
 
+	bitmap_free(result);
+	bitmap_free(tdata.base);
+	bitmap_free(tdata.commits);
+	bitmap_free(tdata.trees);
+	bitmap_free(tdata.blobs);
+	bitmap_free(tdata.tags);
 	free_bitmap_index(bitmap_git);
 }
 
@@ -1748,7 +1759,7 @@
 	struct object_id oid;
 	uint32_t i, index_pos;
 
-	if (!bitmap_git->hashes)
+	if (!bitmap_git || !bitmap_git->hashes)
 		goto cleanup;
 
 	for (i = 0; i < bitmap_num_objects(bitmap_git); i++) {
@@ -1848,9 +1859,17 @@
 	ewah_pool_free(b->trees);
 	ewah_pool_free(b->blobs);
 	ewah_pool_free(b->tags);
+	if (b->bitmaps) {
+		struct stored_bitmap *sb;
+		kh_foreach_value(b->bitmaps, sb, {
+			ewah_pool_free(sb->root);
+			free(sb);
+		});
+	}
 	kh_destroy_oid_map(b->bitmaps);
 	free(b->ext_index.objects);
 	free(b->ext_index.hashes);
+	kh_destroy_oid_pos(b->ext_index.positions);
 	bitmap_free(b->result);
 	bitmap_free(b->haves);
 	if (bitmap_is_midx(b)) {
diff --git a/pack-revindex.c b/pack-revindex.c
index 0e4a31d..70d0fba 100644
--- a/pack-revindex.c
+++ b/pack-revindex.c
@@ -296,14 +296,14 @@
 
 int load_midx_revindex(struct multi_pack_index *m)
 {
-	char *revindex_name;
+	struct strbuf revindex_name = STRBUF_INIT;
 	int ret;
 	if (m->revindex_data)
 		return 0;
 
-	revindex_name = get_midx_rev_filename(m);
+	get_midx_rev_filename(&revindex_name, m);
 
-	ret = load_revindex_from_disk(revindex_name,
+	ret = load_revindex_from_disk(revindex_name.buf,
 				      m->num_objects,
 				      &m->revindex_map,
 				      &m->revindex_len);
@@ -313,7 +313,7 @@
 	m->revindex_data = (const uint32_t *)((const char *)m->revindex_map + RIDX_HEADER_SIZE);
 
 cleanup:
-	free(revindex_name);
+	strbuf_release(&revindex_name);
 	return ret;
 }
 
diff --git a/packfile.c b/packfile.c
index 89402cf..835b2d2 100644
--- a/packfile.c
+++ b/packfile.c
@@ -324,7 +324,8 @@
 	}
 }
 
-void close_pack_revindex(struct packed_git *p) {
+static void close_pack_revindex(struct packed_git *p)
+{
 	if (!p->revindex_map)
 		return;
 
@@ -1060,7 +1061,7 @@
 		unsigned long len, enum object_type *type, unsigned long *sizep)
 {
 	unsigned shift;
-	unsigned long size, c;
+	size_t size, c;
 	unsigned long used = 0;
 
 	c = buf[used++];
@@ -1068,16 +1069,16 @@
 	size = c & 15;
 	shift = 4;
 	while (c & 0x80) {
-		if (len <= used || bitsizeof(long) <= shift) {
+		if (len <= used || (bitsizeof(long) - 7) < shift) {
 			error("bad object header");
 			size = used = 0;
 			break;
 		}
 		c = buf[used++];
-		size += (c & 0x7f) << shift;
+		size = st_add(size, st_left_shift(c & 0x7f, shift));
 		shift += 7;
 	}
-	*sizep = size;
+	*sizep = cast_size_t_to_ulong(size);
 	return used;
 }
 
diff --git a/packfile.h b/packfile.h
index 1861467..a3f6723 100644
--- a/packfile.h
+++ b/packfile.h
@@ -90,7 +90,6 @@
 
 unsigned char *use_pack(struct packed_git *, struct pack_window **, off_t, unsigned long *);
 void close_pack_windows(struct packed_git *);
-void close_pack_revindex(struct packed_git *);
 void close_pack(struct packed_git *);
 void close_object_store(struct raw_object_store *o);
 void unuse_pack(struct pack_window **);
diff --git a/pager.c b/pager.c
index 52f27a6..27877f8 100644
--- a/pager.c
+++ b/pager.c
@@ -8,7 +8,7 @@
 #define DEFAULT_PAGER "less"
 #endif
 
-static struct child_process pager_process = CHILD_PROCESS_INIT;
+static struct child_process pager_process;
 static const char *pager_program;
 
 /* Is the value coming back from term_columns() just a guess? */
@@ -124,6 +124,8 @@
 
 	setenv("GIT_PAGER_IN_USE", "true", 1);
 
+	child_process_init(&pager_process);
+
 	/* spawn the pager */
 	prepare_pager_args(&pager_process, pager);
 	pager_process.in = -1;
diff --git a/parallel-checkout.c b/parallel-checkout.c
index ed9c999..8dd7e7b 100644
--- a/parallel-checkout.c
+++ b/parallel-checkout.c
@@ -261,7 +261,7 @@
 	struct stream_filter *filter;
 	struct strbuf buf = STRBUF_INIT;
 	char *blob;
-	unsigned long size;
+	size_t size;
 	ssize_t wrote;
 
 	/* Sanity check */
diff --git a/parse-options-cb.c b/parse-options-cb.c
index 3c811e1..d346dbe 100644
--- a/parse-options-cb.c
+++ b/parse-options-cb.c
@@ -1,5 +1,6 @@
 #include "git-compat-util.h"
 #include "parse-options.h"
+#include "branch.h"
 #include "cache.h"
 #include "commit.h"
 #include "color.h"
@@ -293,3 +294,18 @@
 
 	return 0;
 }
+
+int parse_opt_tracking_mode(const struct option *opt, const char *arg, int unset)
+{
+	if (unset)
+		*(enum branch_track *)opt->value = BRANCH_TRACK_NEVER;
+	else if (!arg || !strcmp(arg, "direct"))
+		*(enum branch_track *)opt->value = BRANCH_TRACK_EXPLICIT;
+	else if (!strcmp(arg, "inherit"))
+		*(enum branch_track *)opt->value = BRANCH_TRACK_INHERIT;
+	else
+		return error(_("option `%s' expects \"%s\" or \"%s\""),
+			     "--track", "direct", "inherit");
+
+	return 0;
+}
diff --git a/parse-options.c b/parse-options.c
index fc5b43f..a828303 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -404,8 +404,9 @@
 	return PARSE_OPT_UNKNOWN;
 }
 
-static int parse_nodash_opt(struct parse_opt_ctx_t *p, const char *arg,
-			    const struct option *options)
+static enum parse_opt_result parse_nodash_opt(struct parse_opt_ctx_t *p,
+					      const char *arg,
+					      const struct option *options)
 {
 	const struct option *all_opts = options;
 
@@ -415,7 +416,7 @@
 		if (options->short_name == arg[0] && arg[1] == '\0')
 			return get_value(p, options, all_opts, OPT_SHORT);
 	}
-	return -2;
+	return PARSE_OPT_ERROR;
 }
 
 static void check_typos(const char *arg, const struct option *options)
@@ -1075,6 +1076,6 @@
 		   const char * const *usagestr,
 		   const struct option *options)
 {
-	fprintf(stderr, "fatal: %s\n\n", msg);
+	die_message("%s\n", msg); /* The extra \n is intentional */
 	usage_with_options(usagestr, options);
 }
diff --git a/parse-options.h b/parse-options.h
index 275fb44..e22846d 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -301,6 +301,8 @@
 					   const char *, int);
 int parse_opt_passthru(const struct option *, const char *, int);
 int parse_opt_passthru_argv(const struct option *, const char *, int);
+/* value is enum branch_track* */
+int parse_opt_tracking_mode(const struct option *, const char *, int);
 
 #define OPT__VERBOSE(var, h)  OPT_COUNTUP('v', "verbose", (var), (h))
 #define OPT__QUIET(var, h)    OPT_COUNTUP('q', "quiet",   (var), (h))
diff --git a/pathspec.h b/pathspec.h
index 2341dc9..402ebb8 100644
--- a/pathspec.h
+++ b/pathspec.h
@@ -58,8 +58,7 @@
 #define GUARD_PATHSPEC(ps, mask) \
 	do { \
 		if ((ps)->magic & ~(mask))	       \
-			die("BUG:%s:%d: unsupported magic %x",	\
-			    __FILE__, __LINE__, (ps)->magic & ~(mask)); \
+			BUG("unsupported magic %x", (ps)->magic & ~(mask)); \
 	} while (0)
 
 /* parse_pathspec flags */
diff --git a/perl/Git/SVN.pm b/perl/Git/SVN.pm
index 35ff5a6..6ce2e28 100644
--- a/perl/Git/SVN.pm
+++ b/perl/Git/SVN.pm
@@ -6,7 +6,7 @@
 use vars qw/$_no_metadata
             $_repack $_repack_flags $_use_svm_props $_head
             $_use_svnsync_props $no_reuse_existing
-	    $_use_log_author $_add_author_from $_localtime/;
+	    $_use_log_author $_add_author_from $_localtime $_use_fsync/;
 use Carp qw/croak/;
 use File::Path qw/mkpath/;
 use IPC::Open3;
@@ -2269,6 +2269,19 @@
 	}
 }
 
+# TODO: move this to Git.pm?
+sub use_fsync {
+	if (!defined($_use_fsync)) {
+		my $x = $ENV{GIT_TEST_FSYNC};
+		if (defined $x) {
+			my $v = command_oneline('-c', "test.fsync=$x",
+					qw(config --type=bool test.fsync));
+			$_use_fsync = defined($v) ? ($v eq "true\n") : 1;
+		}
+	}
+	$_use_fsync;
+}
+
 sub rev_map_set {
 	my ($self, $rev, $commit, $update_ref, $uuid) = @_;
 	defined $commit or die "missing arg3\n";
@@ -2290,7 +2303,7 @@
 	my $sync;
 	# both of these options make our .rev_db file very, very important
 	# and we can't afford to lose it because rebuild() won't work
-	if ($self->use_svm_props || $self->no_metadata) {
+	if (($self->use_svm_props || $self->no_metadata) && use_fsync()) {
 		require File::Copy;
 		$sync = 1;
 		File::Copy::copy($db, $db_lock) or die "rev_map_set(@_): ",
diff --git a/pkt-line.c b/pkt-line.c
index 2dc8ac2..8e43c2d 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -370,6 +370,32 @@
 	return (val < 0) ? val : (val << 8) | hex2chr(lenbuf_hex + 2);
 }
 
+static char *find_packfile_uri_path(const char *buffer)
+{
+	const char *URI_MARK = "://";
+	char *path;
+	int len;
+
+	/* First char is sideband mark */
+	buffer += 1;
+
+	len = strspn(buffer, "0123456789abcdefABCDEF");
+	/* size of SHA1 and SHA256 hash */
+	if (!(len == 40 || len == 64) || buffer[len] != ' ')
+		return NULL; /* required "<hash>SP" not seen */
+
+	path = strstr(buffer + len + 1, URI_MARK);
+	if (!path)
+		return NULL;
+
+	path = strchr(path + strlen(URI_MARK), '/');
+	if (!path || !*(path + 1))
+		return NULL;
+
+	/* position after '/' */
+	return ++path;
+}
+
 enum packet_read_status packet_read_with_status(int fd, char **src_buffer,
 						size_t *src_len, char *buffer,
 						unsigned size, int *pktlen,
@@ -377,6 +403,7 @@
 {
 	int len;
 	char linelen[4];
+	char *uri_path_start;
 
 	if (get_packet_data(fd, src_buffer, src_len, linelen, 4, options) < 0) {
 		*pktlen = -1;
@@ -427,7 +454,18 @@
 		len--;
 
 	buffer[len] = 0;
-	packet_trace(buffer, len, 0);
+	if (options & PACKET_READ_REDACT_URI_PATH &&
+	    (uri_path_start = find_packfile_uri_path(buffer))) {
+		const char *redacted = "<redacted>";
+		struct strbuf tracebuf = STRBUF_INIT;
+		strbuf_insert(&tracebuf, 0, buffer, len);
+		strbuf_splice(&tracebuf, uri_path_start - buffer,
+			      strlen(uri_path_start), redacted, strlen(redacted));
+		packet_trace(tracebuf.buf, tracebuf.len, 0);
+		strbuf_release(&tracebuf);
+	} else {
+		packet_trace(buffer, len, 0);
+	}
 
 	if ((options & PACKET_READ_DIE_ON_ERR_PACKET) &&
 	    starts_with(buffer, "ERR "))
diff --git a/pkt-line.h b/pkt-line.h
index 467ae01..6d2a63d 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -87,6 +87,7 @@
 #define PACKET_READ_CHOMP_NEWLINE        (1u<<1)
 #define PACKET_READ_DIE_ON_ERR_PACKET    (1u<<2)
 #define PACKET_READ_GENTLE_ON_READ_ERROR (1u<<3)
+#define PACKET_READ_REDACT_URI_PATH      (1u<<4)
 int packet_read(int fd, char *buffer, unsigned size, int options);
 
 /*
diff --git a/po/README.md b/po/README.md
index dcd8436..19fabb4 100644
--- a/po/README.md
+++ b/po/README.md
@@ -221,6 +221,10 @@
 - Adjust the strings so that they're easy to translate. Most of the
   advice in `info '(gettext)Preparing Strings'` applies here.
 
+- Strings referencing numbers of items may need to be split into singular and
+  plural forms; see the Q\_() wrapper in the C sub-section below for an
+  example.
+
 - If something is unclear or ambiguous you can use a "TRANSLATORS"
   comment to tell the translators what to make of it. These will be
   extracted by xgettext(1) and put in the "po/\*.po" files, e.g. from
diff --git a/pretty.c b/pretty.c
index 1af5b09..ee6114e 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1275,28 +1275,66 @@
 
 static size_t parse_describe_args(const char *start, struct strvec *args)
 {
-	const char *options[] = { "match", "exclude" };
+	struct {
+		char *name;
+		enum {
+			DESCRIBE_ARG_BOOL,
+			DESCRIBE_ARG_INTEGER,
+			DESCRIBE_ARG_STRING,
+		} type;
+	}  option[] = {
+		{ "tags", DESCRIBE_ARG_BOOL},
+		{ "abbrev", DESCRIBE_ARG_INTEGER },
+		{ "exclude", DESCRIBE_ARG_STRING },
+		{ "match", DESCRIBE_ARG_STRING },
+	};
 	const char *arg = start;
 
 	for (;;) {
-		const char *matched = NULL;
+		int found = 0;
 		const char *argval;
 		size_t arglen = 0;
+		int optval = 0;
 		int i;
 
-		for (i = 0; i < ARRAY_SIZE(options); i++) {
-			if (match_placeholder_arg_value(arg, options[i], &arg,
-							&argval, &arglen)) {
-				matched = options[i];
+		for (i = 0; !found && i < ARRAY_SIZE(option); i++) {
+			switch (option[i].type) {
+			case DESCRIBE_ARG_BOOL:
+				if (match_placeholder_bool_arg(arg, option[i].name, &arg, &optval)) {
+					if (optval)
+						strvec_pushf(args, "--%s", option[i].name);
+					else
+						strvec_pushf(args, "--no-%s", option[i].name);
+					found = 1;
+				}
+				break;
+			case DESCRIBE_ARG_INTEGER:
+				if (match_placeholder_arg_value(arg, option[i].name, &arg,
+								&argval, &arglen)) {
+					char *endptr;
+					if (!arglen)
+						return 0;
+					strtol(argval, &endptr, 10);
+					if (endptr - argval != arglen)
+						return 0;
+					strvec_pushf(args, "--%s=%.*s", option[i].name, (int)arglen, argval);
+					found = 1;
+				}
+				break;
+			case DESCRIBE_ARG_STRING:
+				if (match_placeholder_arg_value(arg, option[i].name, &arg,
+								&argval, &arglen)) {
+					if (!arglen)
+						return 0;
+					strvec_pushf(args, "--%s=%.*s", option[i].name, (int)arglen, argval);
+					found = 1;
+				}
 				break;
 			}
 		}
-		if (!matched)
+		if (!found)
 			break;
 
-		if (!arglen)
-			return 0;
-		strvec_pushf(args, "--%s=%.*s", matched, (int)arglen, argval);
 	}
 	return arg - start;
 }
diff --git a/prompt.c b/prompt.c
index 5ded21a..50df172 100644
--- a/prompt.c
+++ b/prompt.c
@@ -8,15 +8,12 @@
 static char *do_askpass(const char *cmd, const char *prompt)
 {
 	struct child_process pass = CHILD_PROCESS_INIT;
-	const char *args[3];
 	static struct strbuf buffer = STRBUF_INIT;
 	int err = 0;
 
-	args[0] = cmd;
-	args[1]	= prompt;
-	args[2] = NULL;
+	strvec_push(&pass.args, cmd);
+	strvec_push(&pass.args, prompt);
 
-	pass.argv = args;
 	pass.out = -1;
 
 	if (start_command(&pass))
diff --git a/range-diff.c b/range-diff.c
index cac89a2..30a4de5 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -556,7 +556,7 @@
 	struct string_list branch2 = STRING_LIST_INIT_DUP;
 
 	if (range_diff_opts->left_only && range_diff_opts->right_only)
-		res = error(_("--left-only and --right-only are mutually exclusive"));
+		res = error(_("options '%s' and '%s' cannot be used together"), "--left-only", "--right-only");
 
 	if (!res && read_patches(range1, &branch1, range_diff_opts->other_arg))
 		res = error(_("could not parse log for '%s'"), range1);
diff --git a/read-cache.c b/read-cache.c
index f398659..cbe73f1 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -68,6 +68,11 @@
  */
 #define CACHE_ENTRY_PATH_LENGTH 80
 
+enum index_search_mode {
+	NO_EXPAND_SPARSE = 0,
+	EXPAND_SPARSE = 1
+};
+
 static inline struct cache_entry *mem_pool__ce_alloc(struct mem_pool *mem_pool, size_t len)
 {
 	struct cache_entry *ce;
@@ -551,7 +556,10 @@
 	return 0;
 }
 
-static int index_name_stage_pos(struct index_state *istate, const char *name, int namelen, int stage)
+static int index_name_stage_pos(struct index_state *istate,
+				const char *name, int namelen,
+				int stage,
+				enum index_search_mode search_mode)
 {
 	int first, last;
 
@@ -570,7 +578,7 @@
 		first = next+1;
 	}
 
-	if (istate->sparse_index &&
+	if (search_mode == EXPAND_SPARSE && istate->sparse_index &&
 	    first > 0) {
 		/* Note: first <= istate->cache_nr */
 		struct cache_entry *ce = istate->cache[first - 1];
@@ -586,7 +594,7 @@
 		    ce_namelen(ce) < namelen &&
 		    !strncmp(name, ce->name, ce_namelen(ce))) {
 			ensure_full_index(istate);
-			return index_name_stage_pos(istate, name, namelen, stage);
+			return index_name_stage_pos(istate, name, namelen, stage, search_mode);
 		}
 	}
 
@@ -595,7 +603,12 @@
 
 int index_name_pos(struct index_state *istate, const char *name, int namelen)
 {
-	return index_name_stage_pos(istate, name, namelen, 0);
+	return index_name_stage_pos(istate, name, namelen, 0, EXPAND_SPARSE);
+}
+
+int index_entry_exists(struct index_state *istate, const char *name, int namelen)
+{
+	return index_name_stage_pos(istate, name, namelen, 0, NO_EXPAND_SPARSE) >= 0;
 }
 
 int remove_index_entry_at(struct index_state *istate, int pos)
@@ -1237,7 +1250,7 @@
 			 */
 		}
 
-		pos = index_name_stage_pos(istate, name, len, stage);
+		pos = index_name_stage_pos(istate, name, len, stage, EXPAND_SPARSE);
 		if (pos >= 0) {
 			/*
 			 * Found one, but not so fast.  This could
@@ -1337,7 +1350,7 @@
 		strcmp(ce->name, istate->cache[istate->cache_nr - 1]->name) > 0)
 		pos = index_pos_to_insert_pos(istate->cache_nr);
 	else
-		pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
+		pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce), EXPAND_SPARSE);
 
 	/* existing match? Just replace it. */
 	if (pos >= 0) {
@@ -1372,7 +1385,7 @@
 		if (!ok_to_replace)
 			return error(_("'%s' appears as both a file and as a directory"),
 				     ce->name);
-		pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
+		pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce), EXPAND_SPARSE);
 		pos = -pos-1;
 	}
 	return pos + 1;
@@ -2352,9 +2365,17 @@
 
 	if (!istate->repo)
 		istate->repo = the_repository;
+
+	/*
+	 * If the command explicitly requires a full index, force it
+	 * to be full. Otherwise, correct the sparsity based on repository
+	 * settings and other properties of the index (if necessary).
+	 */
 	prepare_repo_settings(istate->repo);
 	if (istate->repo->settings.command_requires_full_index)
 		ensure_full_index(istate);
+	else
+		ensure_correct_sparsity(istate);
 
 	return istate->cache_nr;
 
diff --git a/ref-filter.c b/ref-filter.c
index 08a3f83..f7a2f17 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -341,7 +341,7 @@
 		else
 			oi.info.disk_sizep = &oi.disk_size;
 	} else
-		return strbuf_addf_ret(err, -1, _("unrecognized %%(objectsize) argument: %s"), arg);
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(%s) argument: %s"), "objectsize", arg);
 	return 0;
 }
 
@@ -374,7 +374,7 @@
 	else if (!strcmp(arg, "sanitize"))
 		atom->u.contents.option = C_SUB_SANITIZE;
 	else
-		return strbuf_addf_ret(err, -1, _("unrecognized %%(subject) argument: %s"), arg);
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(%s) argument: %s"), "subject", arg);
 	return 0;
 }
 
@@ -428,7 +428,7 @@
 		if (strtoul_ui(arg, 10, &atom->u.contents.nlines))
 			return strbuf_addf_ret(err, -1, _("positive value expected contents:lines=%s"), arg);
 	} else
-		return strbuf_addf_ret(err, -1, _("unrecognized %%(contents) argument: %s"), arg);
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(%s) argument: %s"), "contents", arg);
 	return 0;
 }
 
@@ -440,7 +440,7 @@
 	else if (!strcmp(arg, "size"))
 		atom->u.raw_data.option = RAW_LENGTH;
 	else
-		return strbuf_addf_ret(err, -1, _("unrecognized %%(raw) argument: %s"), arg);
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(%s) argument: %s"), "raw", arg);
 	return 0;
 }
 
@@ -459,7 +459,7 @@
 		if (atom->u.oid.length < MINIMUM_ABBREV)
 			atom->u.oid.length = MINIMUM_ABBREV;
 	} else
-		return strbuf_addf_ret(err, -1, _("unrecognized argument '%s' in %%(%s)"), arg, atom->name);
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(%s) argument: %s"), atom->name, arg);
 	return 0;
 }
 
@@ -531,7 +531,7 @@
 		else if ((position = parse_align_position(s)) >= 0)
 			align->position = position;
 		else {
-			strbuf_addf(err, _("unrecognized %%(align) argument: %s"), s);
+			strbuf_addf(err, _("unrecognized %%(%s) argument: %s"), "align", s);
 			string_list_clear(&params, 0);
 			return -1;
 		}
@@ -557,7 +557,7 @@
 	} else if (skip_prefix(arg, "notequals=", &atom->u.if_then_else.str)) {
 		atom->u.if_then_else.cmp_status = COMPARE_UNEQUAL;
 	} else
-		return strbuf_addf_ret(err, -1, _("unrecognized %%(if) argument: %s"), arg);
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(%s) argument: %s"), "if", arg);
 	return 0;
 }
 
@@ -841,7 +841,7 @@
 	struct if_then_else *if_then_else = (struct if_then_else *)cur->at_end_data;
 
 	if (!if_then_else->then_atom_seen)
-		die(_("format: %%(if) atom used without a %%(then) atom"));
+		die(_("format: %%(%s) atom used without a %%(%s) atom"), "if", "then");
 
 	if (if_then_else->else_atom_seen) {
 		/*
@@ -907,7 +907,7 @@
 	if (cur->at_end == if_then_else_handler)
 		if_then_else = (struct if_then_else *)cur->at_end_data;
 	if (!if_then_else)
-		return strbuf_addf_ret(err, -1, _("format: %%(then) atom used without an %%(if) atom"));
+		return strbuf_addf_ret(err, -1, _("format: %%(%s) atom used without a %%(%s) atom"), "then", "if");
 	if (if_then_else->then_atom_seen)
 		return strbuf_addf_ret(err, -1, _("format: %%(then) atom used more than once"));
 	if (if_then_else->else_atom_seen)
@@ -943,9 +943,9 @@
 	if (prev->at_end == if_then_else_handler)
 		if_then_else = (struct if_then_else *)prev->at_end_data;
 	if (!if_then_else)
-		return strbuf_addf_ret(err, -1, _("format: %%(else) atom used without an %%(if) atom"));
+		return strbuf_addf_ret(err, -1, _("format: %%(%s) atom used without a %%(%s) atom"), "else", "if");
 	if (!if_then_else->then_atom_seen)
-		return strbuf_addf_ret(err, -1, _("format: %%(else) atom used without a %%(then) atom"));
+		return strbuf_addf_ret(err, -1, _("format: %%(%s) atom used without a %%(%s) atom"), "else", "then");
 	if (if_then_else->else_atom_seen)
 		return strbuf_addf_ret(err, -1, _("format: %%(else) atom used more than once"));
 	if_then_else->else_atom_seen = 1;
@@ -2470,6 +2470,12 @@
 	return 0;
 }
 
+struct ref_sorting {
+	struct ref_sorting *next;
+	int atom; /* index into used_atom array (internal) */
+	enum ref_sorting_order sort_flags;
+};
+
 static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, struct ref_array_item *b)
 {
 	struct atom_value *va, *vb;
@@ -2663,7 +2669,7 @@
 }
 
 /*  If no sorting option is given, use refname to sort as default */
-struct ref_sorting *ref_default_sorting(void)
+static struct ref_sorting *ref_default_sorting(void)
 {
 	static const char cstr_name[] = "refname";
 
@@ -2674,7 +2680,7 @@
 	return sorting;
 }
 
-void parse_ref_sorting(struct ref_sorting **sorting_tail, const char *arg)
+static void parse_ref_sorting(struct ref_sorting **sorting_tail, const char *arg)
 {
 	struct ref_sorting *s;
 
@@ -2692,17 +2698,25 @@
 	s->atom = parse_sorting_atom(arg);
 }
 
-int parse_opt_ref_sorting(const struct option *opt, const char *arg, int unset)
+struct ref_sorting *ref_sorting_options(struct string_list *options)
 {
-	/*
-	 * NEEDSWORK: We should probably clear the list in this case, but we've
-	 * already munged the global used_atoms list, which would need to be
-	 * undone.
-	 */
-	BUG_ON_OPT_NEG(unset);
+	struct string_list_item *item;
+	struct ref_sorting *sorting = NULL, **tail = &sorting;
 
-	parse_ref_sorting(opt->value, arg);
-	return 0;
+	if (!options->nr) {
+		sorting = ref_default_sorting();
+	} else {
+		for_each_string_list_item(item, options)
+			parse_ref_sorting(tail, item->string);
+	}
+
+	/*
+	 * From here on, the ref_sorting list should be used to talk
+	 * about the sort order used for the output.  The caller
+	 * should not touch the string form anymore.
+	 */
+	string_list_clear(options, 0);
+	return sorting;
 }
 
 void ref_sorting_release(struct ref_sorting *sorting)
diff --git a/ref-filter.h b/ref-filter.h
index 6228458..aa0eea4 100644
--- a/ref-filter.h
+++ b/ref-filter.h
@@ -23,16 +23,13 @@
 #define FILTER_REFS_KIND_MASK      (FILTER_REFS_ALL | FILTER_REFS_DETACHED_HEAD)
 
 struct atom_value;
+struct ref_sorting;
 
-struct ref_sorting {
-	struct ref_sorting *next;
-	int atom; /* index into used_atom array (internal) */
-	enum {
-		REF_SORTING_REVERSE = 1<<0,
-		REF_SORTING_ICASE = 1<<1,
-		REF_SORTING_VERSION = 1<<2,
-		REF_SORTING_DETACHED_HEAD_FIRST = 1<<3,
-	} sort_flags;
+enum ref_sorting_order {
+	REF_SORTING_REVERSE = 1<<0,
+	REF_SORTING_ICASE = 1<<1,
+	REF_SORTING_VERSION = 1<<2,
+	REF_SORTING_DETACHED_HEAD_FIRST = 1<<3,
 };
 
 struct ref_array_item {
@@ -97,9 +94,8 @@
 #define OPT_NO_MERGED(f, h) _OPT_MERGED_NO_MERGED("no-merged", f, h)
 
 #define OPT_REF_SORT(var) \
-	OPT_CALLBACK_F(0, "sort", (var), \
-		       N_("key"), N_("field name to sort on"), \
-		       PARSE_OPT_NONEG, parse_opt_ref_sorting)
+	OPT_STRING_LIST(0, "sort", (var), \
+			N_("key"), N_("field name to sort on"))
 
 /*
  * API for filtering a set of refs. Based on the type of refs the user
@@ -121,14 +117,10 @@
 			  struct ref_format *format,
 			  struct strbuf *final_buf,
 			  struct strbuf *error_buf);
-/*  Parse a single sort specifier and add it to the list */
-void parse_ref_sorting(struct ref_sorting **sorting_tail, const char *atom);
-/*  Callback function for parsing the sort option */
-int parse_opt_ref_sorting(const struct option *opt, const char *arg, int unset);
-/*  Default sort option based on refname */
-struct ref_sorting *ref_default_sorting(void);
 /* Release a "struct ref_sorting" */
 void ref_sorting_release(struct ref_sorting *);
+/*  Convert list of sort options into ref_sorting */
+struct ref_sorting *ref_sorting_options(struct string_list *);
 /*  Function to parse --merged and --no-merged options */
 int parse_opt_merge_filter(const struct option *opt, const char *arg, int unset);
 /*  Get the current HEAD's description */
diff --git a/refs.c b/refs.c
index d7cc0a2..addb262 100644
--- a/refs.c
+++ b/refs.c
@@ -269,9 +269,10 @@
 			  struct object_id *oid, int *flags)
 {
 	const char *result;
+	int ignore_errno;
 
 	result = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
-					 oid, flags);
+					 oid, flags, &ignore_errno);
 	return xstrdup_or_null(result);
 }
 
@@ -291,18 +292,15 @@
 	void *cb_data;
 };
 
-int refs_read_ref_full(struct ref_store *refs, const char *refname,
-		       int resolve_flags, struct object_id *oid, int *flags)
-{
-	if (refs_resolve_ref_unsafe(refs, refname, resolve_flags, oid, flags))
-		return 0;
-	return -1;
-}
-
 int read_ref_full(const char *refname, int resolve_flags, struct object_id *oid, int *flags)
 {
-	return refs_read_ref_full(get_main_ref_store(the_repository), refname,
-				  resolve_flags, oid, flags);
+	int ignore_errno;
+	struct ref_store *refs = get_main_ref_store(the_repository);
+
+	if (refs_resolve_ref_unsafe(refs, refname, resolve_flags,
+				    oid, flags, &ignore_errno))
+		return 0;
+	return -1;
 }
 
 int read_ref(const char *refname, struct object_id *oid)
@@ -312,7 +310,9 @@
 
 int refs_ref_exists(struct ref_store *refs, const char *refname)
 {
-	return !!refs_resolve_ref_unsafe(refs, refname, RESOLVE_REF_READING, NULL, NULL);
+	int ignore_errno;
+	return !!refs_resolve_ref_unsafe(refs, refname, RESOLVE_REF_READING,
+					 NULL, NULL, &ignore_errno);
 }
 
 int ref_exists(const char *refname)
@@ -655,13 +655,16 @@
 		struct object_id oid_from_ref;
 		struct object_id *this_result;
 		int flag;
+		struct ref_store *refs = get_main_ref_store(repo);
+		int ignore_errno;
 
 		this_result = refs_found ? &oid_from_ref : oid;
 		strbuf_reset(&fullref);
 		strbuf_addf(&fullref, *p, len, str);
-		r = refs_resolve_ref_unsafe(get_main_ref_store(repo),
-					    fullref.buf, RESOLVE_REF_READING,
-					    this_result, &flag);
+		r = refs_resolve_ref_unsafe(refs, fullref.buf,
+					    RESOLVE_REF_READING,
+					    this_result, &flag,
+					    &ignore_errno);
 		if (r) {
 			if (!refs_found++)
 				*ref = xstrdup(r);
@@ -690,12 +693,14 @@
 	for (p = ref_rev_parse_rules; *p; p++) {
 		struct object_id hash;
 		const char *ref, *it;
+		int ignore_errno;
 
 		strbuf_reset(&path);
 		strbuf_addf(&path, *p, len, str);
 		ref = refs_resolve_ref_unsafe(refs, path.buf,
 					      RESOLVE_REF_READING,
-					      oid ? &hash : NULL, NULL);
+					      oid ? &hash : NULL, NULL,
+					      &ignore_errno);
 		if (!ref)
 			continue;
 		if (refs_reflog_exists(refs, path.buf))
@@ -1078,9 +1083,10 @@
 {
 	assert(err);
 
-	if ((new_oid && !is_null_oid(new_oid)) ?
-	    check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
-	    !refname_is_safe(refname)) {
+	if (!(flags & REF_SKIP_REFNAME_VERIFICATION) &&
+	    ((new_oid && !is_null_oid(new_oid)) ?
+		     check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
+			   !refname_is_safe(refname))) {
 		strbuf_addf(err, _("refusing to update ref with bad name '%s'"),
 			    refname);
 		return -1;
@@ -1089,6 +1095,13 @@
 	if (flags & ~REF_TRANSACTION_UPDATE_ALLOWED_FLAGS)
 		BUG("illegal flags 0x%x passed to ref_transaction_update()", flags);
 
+	/*
+	 * Clear flags outside the allowed set; this should be a noop because
+	 * of the BUG() check above, but it works around a -Wnonnull warning
+	 * with some versions of "gcc -O3".
+	 */
+	flags &= REF_TRANSACTION_UPDATE_ALLOWED_FLAGS;
+
 	flags |= (new_oid ? REF_HAVE_NEW : 0) | (old_oid ? REF_HAVE_OLD : 0);
 
 	ref_transaction_add_update(transaction, refname, flags,
@@ -1373,32 +1386,14 @@
 	return NULL;
 }
 
-int refs_rename_ref_available(struct ref_store *refs,
-			      const char *old_refname,
-			      const char *new_refname)
-{
-	struct string_list skip = STRING_LIST_INIT_NODUP;
-	struct strbuf err = STRBUF_INIT;
-	int ok;
-
-	string_list_insert(&skip, old_refname);
-	ok = !refs_verify_refname_available(refs, new_refname,
-					    NULL, &skip, &err);
-	if (!ok)
-		error("%s", err.buf);
-
-	string_list_clear(&skip, 0);
-	strbuf_release(&err);
-	return ok;
-}
-
 int refs_head_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 {
 	struct object_id oid;
 	int flag;
+	int ignore_errno;
 
-	if (!refs_read_ref_full(refs, "HEAD", RESOLVE_REF_READING,
-				&oid, &flag))
+	if (refs_resolve_ref_unsafe(refs, "HEAD", RESOLVE_REF_READING,
+				    &oid, &flag, &ignore_errno))
 		return fn("HEAD", &oid, flag, cb_data);
 
 	return 0;
@@ -1649,7 +1644,8 @@
 
 static int refs_read_special_head(struct ref_store *ref_store,
 				  const char *refname, struct object_id *oid,
-				  struct strbuf *referent, unsigned int *type)
+				  struct strbuf *referent, unsigned int *type,
+				  int *failure_errno)
 {
 	struct strbuf full_path = STRBUF_INIT;
 	struct strbuf content = STRBUF_INIT;
@@ -1659,7 +1655,8 @@
 	if (strbuf_read_file(&content, full_path.buf, 0) < 0)
 		goto done;
 
-	result = parse_loose_ref_contents(content.buf, oid, referent, type);
+	result = parse_loose_ref_contents(content.buf, oid, referent, type,
+					  failure_errno);
 
 done:
 	strbuf_release(&full_path);
@@ -1667,30 +1664,33 @@
 	return result;
 }
 
-int refs_read_raw_ref(struct ref_store *ref_store,
-		      const char *refname, struct object_id *oid,
-		      struct strbuf *referent, unsigned int *type)
+int refs_read_raw_ref(struct ref_store *ref_store, const char *refname,
+		      struct object_id *oid, struct strbuf *referent,
+		      unsigned int *type, int *failure_errno)
 {
+	assert(failure_errno);
 	if (!strcmp(refname, "FETCH_HEAD") || !strcmp(refname, "MERGE_HEAD")) {
 		return refs_read_special_head(ref_store, refname, oid, referent,
-					      type);
+					      type, failure_errno);
 	}
 
 	return ref_store->be->read_raw_ref(ref_store, refname, oid, referent,
-					   type, &errno);
+					   type, failure_errno);
 }
 
-/* This function needs to return a meaningful errno on failure */
 const char *refs_resolve_ref_unsafe(struct ref_store *refs,
 				    const char *refname,
 				    int resolve_flags,
-				    struct object_id *oid, int *flags)
+				    struct object_id *oid,
+				    int *flags, int *failure_errno)
 {
 	static struct strbuf sb_refname = STRBUF_INIT;
 	struct object_id unused_oid;
 	int unused_flags;
 	int symref_count;
 
+	assert(failure_errno);
+
 	if (!oid)
 		oid = &unused_oid;
 	if (!flags)
@@ -1701,7 +1701,7 @@
 	if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
 		if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
 		    !refname_is_safe(refname)) {
-			errno = EINVAL;
+			*failure_errno = EINVAL;
 			return NULL;
 		}
 
@@ -1719,8 +1719,8 @@
 	for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
 		unsigned int read_flags = 0;
 
-		if (refs_read_raw_ref(refs, refname,
-				      oid, &sb_refname, &read_flags)) {
+		if (refs_read_raw_ref(refs, refname, oid, &sb_refname,
+				      &read_flags, failure_errno)) {
 			*flags |= read_flags;
 
 			/* In reading mode, refs must eventually resolve */
@@ -1732,9 +1732,9 @@
 			 * may show errors besides ENOENT if there are
 			 * similarly-named refs.
 			 */
-			if (errno != ENOENT &&
-			    errno != EISDIR &&
-			    errno != ENOTDIR)
+			if (*failure_errno != ENOENT &&
+			    *failure_errno != EISDIR &&
+			    *failure_errno != ENOTDIR)
 				return NULL;
 
 			oidclr(oid);
@@ -1761,7 +1761,7 @@
 		if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
 			if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
 			    !refname_is_safe(refname)) {
-				errno = EINVAL;
+				*failure_errno = EINVAL;
 				return NULL;
 			}
 
@@ -1769,7 +1769,7 @@
 		}
 	}
 
-	errno = ELOOP;
+	*failure_errno = ELOOP;
 	return NULL;
 }
 
@@ -1784,8 +1784,10 @@
 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
 			       struct object_id *oid, int *flags)
 {
+	int ignore_errno;
+
 	return refs_resolve_ref_unsafe(get_main_ref_store(the_repository), refname,
-				       resolve_flags, oid, flags);
+				       resolve_flags, oid, flags, &ignore_errno);
 }
 
 int resolve_gitlink_ref(const char *submodule, const char *refname,
@@ -1793,14 +1795,15 @@
 {
 	struct ref_store *refs;
 	int flags;
+	int ignore_errno;
 
 	refs = get_submodule_ref_store(submodule);
 
 	if (!refs)
 		return -1;
 
-	if (!refs_resolve_ref_unsafe(refs, refname, 0, oid, &flags) ||
-	    is_null_oid(oid))
+	if (!refs_resolve_ref_unsafe(refs, refname, 0, oid, &flags,
+				     &ignore_errno) || is_null_oid(oid))
 		return -1;
 	return 0;
 }
@@ -2002,10 +2005,12 @@
 	return refs;
 }
 
-void base_ref_store_init(struct ref_store *refs,
-			 const struct ref_storage_be *be)
+void base_ref_store_init(struct ref_store *refs, struct repository *repo,
+			 const char *path, const struct ref_storage_be *be)
 {
 	refs->be = be;
+	refs->repo = repo;
+	refs->gitdir = xstrdup(path);
 }
 
 /* backend functions */
@@ -2102,8 +2107,11 @@
 			    update->refname);
 
 		if (write_in_full(proc.in, buf.buf, buf.len) < 0) {
-			if (errno != EPIPE)
+			if (errno != EPIPE) {
+				/* Don't leak errno outside this API */
+				errno = 0;
 				ret = -1;
+			}
 			break;
 		}
 	}
@@ -2137,7 +2145,7 @@
 		break;
 	}
 
-	if (getenv(GIT_QUARANTINE_ENVIRONMENT)) {
+	if (refs->repo->objects->odb->disable_ref_updates) {
 		strbuf_addstr(err,
 			      _("ref updates forbidden inside quarantine environment"));
 		return -1;
@@ -2238,6 +2246,13 @@
 
 	strbuf_grow(&dirname, strlen(refname) + 1);
 	for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
+		/*
+		 * Just saying "Is a directory" when we e.g. can't
+		 * lock some multi-level ref isn't very informative,
+		 * the user won't be told *what* is a directory, so
+		 * let's not use strerror() below.
+		 */
+		int ignore_errno;
 		/* Expand dirname to the new prefix, not including the trailing slash: */
 		strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
 
@@ -2249,7 +2264,8 @@
 		if (skip && string_list_has_string(skip, dirname.buf))
 			continue;
 
-		if (!refs_read_raw_ref(refs, dirname.buf, &oid, &referent, &type)) {
+		if (!refs_read_raw_ref(refs, dirname.buf, &oid, &referent,
+				       &type, &ignore_errno)) {
 			strbuf_addf(err, _("'%s' exists; cannot create '%s'"),
 				    dirname.buf, refname);
 			goto cleanup;
@@ -2358,16 +2374,15 @@
 }
 
 int refs_create_reflog(struct ref_store *refs, const char *refname,
-		       int force_create, struct strbuf *err)
-{
-	return refs->be->create_reflog(refs, refname, force_create, err);
-}
-
-int safe_create_reflog(const char *refname, int force_create,
 		       struct strbuf *err)
 {
+	return refs->be->create_reflog(refs, refname, err);
+}
+
+int safe_create_reflog(const char *refname, struct strbuf *err)
+{
 	return refs_create_reflog(get_main_ref_store(the_repository), refname,
-				  force_create, err);
+				  err);
 }
 
 int refs_delete_reflog(struct ref_store *refs, const char *refname)
diff --git a/refs.h b/refs.h
index d5099d4..8f91a7f 100644
--- a/refs.h
+++ b/refs.h
@@ -58,6 +58,11 @@
  * resolved. The function returns NULL for such ref names.
  * Caps and underscores refers to the special refs, such as HEAD,
  * FETCH_HEAD and friends, that all live outside of the refs/ directory.
+ *
+ * Callers should not inspect "errno" on failure, but rather pass in a
+ * "failure_errno" parameter, on failure the "errno" will indicate the
+ * type of failure encountered, but not necessarily one that came from
+ * a syscall. We might have faked it up.
  */
 #define RESOLVE_REF_READING 0x01
 #define RESOLVE_REF_NO_RECURSE 0x02
@@ -67,7 +72,8 @@
 				    const char *refname,
 				    int resolve_flags,
 				    struct object_id *oid,
-				    int *flags);
+				    int *flags, int *failure_errno);
+
 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
 			       struct object_id *oid, int *flags);
 
@@ -77,8 +83,6 @@
 char *resolve_refdup(const char *refname, int resolve_flags,
 		     struct object_id *oid, int *flags);
 
-int refs_read_ref_full(struct ref_store *refs, const char *refname,
-		       int resolve_flags, struct object_id *oid, int *flags);
 int read_ref_full(const char *refname, int resolve_flags,
 		  struct object_id *oid, int *flags);
 int read_ref(const char *refname, struct object_id *oid);
@@ -413,8 +417,8 @@
  * Setup reflog before using. Fill in err and return -1 on failure.
  */
 int refs_create_reflog(struct ref_store *refs, const char *refname,
-		       int force_create, struct strbuf *err);
-int safe_create_reflog(const char *refname, int force_create, struct strbuf *err);
+		       struct strbuf *err);
+int safe_create_reflog(const char *refname, struct strbuf *err);
 
 /** Reads log for the value of ref during at_time. **/
 int read_ref_at(struct ref_store *refs,
@@ -459,7 +463,29 @@
 
 /*
  * Callback to process a reflog entry found by the iteration functions (see
- * below)
+ * below).
+ *
+ * The committer parameter is a single string, in the form
+ * "$GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>" (without double quotes).
+ *
+ * The timestamp parameter gives the time when entry was created as the number
+ * of seconds since the UNIX epoch.
+ *
+ * The tz parameter gives the timezone offset for the user who created
+ * the reflog entry, and its value gives a positive or negative offset
+ * from UTC.  Its absolute value is formed by multiplying the hour
+ * part by 100 and adding the minute part.  For example, 1 hour ahead
+ * of UTC, CET == "+0100", is represented as positive one hundred (not
+ * postiive sixty).
+ *
+ * The msg parameter is a single complete line; a reflog message given
+ * to refs_delete_ref, refs_update_ref, etc. is returned to the
+ * callback normalized---each run of whitespaces are squashed into a
+ * single whitespace, trailing whitespace, if exists, is trimmed, and
+ * then a single LF is added at the end.
+ *
+ * The cb_data is a caller-supplied pointer given to the iterator
+ * functions.
  */
 typedef int each_reflog_ent_fn(
 		struct object_id *old_oid, struct object_id *new_oid,
@@ -612,11 +638,23 @@
 #define REF_FORCE_CREATE_REFLOG (1 << 1)
 
 /*
+ * Blindly write an object_id. This is useful for testing data corruption
+ * scenarios.
+ */
+#define REF_SKIP_OID_VERIFICATION (1 << 10)
+
+/*
+ * Skip verifying refname. This is useful for testing data corruption scenarios.
+ */
+#define REF_SKIP_REFNAME_VERIFICATION (1 << 11)
+
+/*
  * Bitmask of all of the flags that are allowed to be passed in to
  * ref_transaction_update() and friends:
  */
-#define REF_TRANSACTION_UPDATE_ALLOWED_FLAGS \
-	(REF_NO_DEREF | REF_FORCE_CREATE_REFLOG)
+#define REF_TRANSACTION_UPDATE_ALLOWED_FLAGS                                  \
+	(REF_NO_DEREF | REF_FORCE_CREATE_REFLOG | REF_SKIP_OID_VERIFICATION | \
+	 REF_SKIP_REFNAME_VERIFICATION)
 
 /*
  * Add a reference update to transaction. `new_oid` is the value that
@@ -782,8 +820,7 @@
 enum expire_reflog_flags {
 	EXPIRE_REFLOGS_DRY_RUN = 1 << 0,
 	EXPIRE_REFLOGS_UPDATE_REF = 1 << 1,
-	EXPIRE_REFLOGS_VERBOSE = 1 << 2,
-	EXPIRE_REFLOGS_REWRITE = 1 << 3
+	EXPIRE_REFLOGS_REWRITE = 1 << 2,
 };
 
 /*
diff --git a/refs/debug.c b/refs/debug.c
index 8667c64..2b0771c 100644
--- a/refs/debug.c
+++ b/refs/debug.c
@@ -26,7 +26,8 @@
 	be_copy->name = store->be->name;
 	trace_printf_key(&trace_refs, "ref_store for %s\n", gitdir);
 	res->refs = store;
-	base_ref_store_init((struct ref_store *)res, be_copy);
+	base_ref_store_init((struct ref_store *)res, store->repo, gitdir,
+			    be_copy);
 	return (struct ref_store *)res;
 }
 
@@ -47,7 +48,8 @@
 	transaction->ref_store = drefs->refs;
 	res = drefs->refs->be->transaction_prepare(drefs->refs, transaction,
 						   err);
-	trace_printf_key(&trace_refs, "transaction_prepare: %d\n", res);
+	trace_printf_key(&trace_refs, "transaction_prepare: %d \"%s\"\n", res,
+			 err->buf);
 	return res;
 }
 
@@ -284,6 +286,7 @@
 	int ret;
 	char o[GIT_MAX_HEXSZ + 1] = "null";
 	char n[GIT_MAX_HEXSZ + 1] = "null";
+	char *msgend = strchrnul(msg, '\n');
 	if (old_oid)
 		oid_to_hex_r(o, old_oid);
 	if (new_oid)
@@ -291,8 +294,10 @@
 
 	ret = dbg->fn(old_oid, new_oid, committer, timestamp, tz, msg,
 		      dbg->cb_data);
-	trace_printf_key(&trace_refs, "reflog_ent %s (ret %d): %s -> %s, %s %ld \"%s\"\n",
-		dbg->refname, ret, o, n, committer, (long int)timestamp, msg);
+	trace_printf_key(&trace_refs,
+			 "reflog_ent %s (ret %d): %s -> %s, %s %ld \"%.*s\"\n",
+			 dbg->refname, ret, o, n, committer,
+			 (long int)timestamp, (int)(msgend - msg), msg);
 	return ret;
 }
 
@@ -339,11 +344,10 @@
 }
 
 static int debug_create_reflog(struct ref_store *ref_store, const char *refname,
-			       int force_create, struct strbuf *err)
+			       struct strbuf *err)
 {
 	struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
-	int res = drefs->refs->be->create_reflog(drefs->refs, refname,
-						 force_create, err);
+	int res = drefs->refs->be->create_reflog(drefs->refs, refname, err);
 	trace_printf_key(&trace_refs, "create_reflog: %s: %d\n", refname, res);
 	return res;
 }
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 151b005..43a3b88 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -16,8 +16,7 @@
  * This backend uses the following flags in `ref_update::flags` for
  * internal bookkeeping purposes. Their numerical values must not
  * conflict with REF_NO_DEREF, REF_FORCE_CREATE_REFLOG, REF_HAVE_NEW,
- * REF_HAVE_OLD, or REF_IS_PRUNING, which are also stored in
- * `ref_update::flags`.
+ * or REF_HAVE_OLD, which are also stored in `ref_update::flags`.
  */
 
 /*
@@ -87,16 +86,12 @@
 	struct ref_store *ref_store = (struct ref_store *)refs;
 	struct strbuf sb = STRBUF_INIT;
 
-	ref_store->repo = repo;
-	ref_store->gitdir = xstrdup(gitdir);
-	base_ref_store_init(ref_store, &refs_be_files);
+	base_ref_store_init(ref_store, repo, gitdir, &refs_be_files);
 	refs->store_flags = flags;
-
 	get_common_dir_noenv(&sb, gitdir);
 	refs->gitcommondir = strbuf_detach(&sb, NULL);
-	strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir);
-	refs->packed_ref_store = packed_ref_store_create(repo, sb.buf, flags);
-	strbuf_release(&sb);
+	refs->packed_ref_store =
+		packed_ref_store_create(repo, refs->gitcommondir, flags);
 
 	chdir_notify_reparent("files-backend $GIT_DIR", &refs->base.gitdir);
 	chdir_notify_reparent("files-backend $GIT_COMMONDIR",
@@ -282,10 +277,11 @@
 					 create_dir_entry(dir->cache, refname.buf,
 							  refname.len));
 		} else {
+			int ignore_errno;
 			if (!refs_resolve_ref_unsafe(&refs->base,
 						     refname.buf,
 						     RESOLVE_REF_READING,
-						     &oid, &flag)) {
+						     &oid, &flag, &ignore_errno)) {
 				oidclr(&oid);
 				flag |= REF_ISBROKEN;
 			} else if (is_null_oid(&oid)) {
@@ -357,6 +353,7 @@
 	int fd;
 	int ret = -1;
 	int remaining_retries = 3;
+	int myerr = 0;
 
 	*type = 0;
 	strbuf_reset(&sb_path);
@@ -383,11 +380,13 @@
 		goto out;
 
 	if (lstat(path, &st) < 0) {
-		if (errno != ENOENT)
+		int ignore_errno;
+		myerr = errno;
+		if (myerr != ENOENT)
 			goto out;
-		if (refs_read_raw_ref(refs->packed_ref_store, refname,
-				      oid, referent, type)) {
-			errno = ENOENT;
+		if (refs_read_raw_ref(refs->packed_ref_store, refname, oid,
+				      referent, type, &ignore_errno)) {
+			myerr = ENOENT;
 			goto out;
 		}
 		ret = 0;
@@ -398,7 +397,8 @@
 	if (S_ISLNK(st.st_mode)) {
 		strbuf_reset(&sb_contents);
 		if (strbuf_readlink(&sb_contents, path, st.st_size) < 0) {
-			if (errno == ENOENT || errno == EINVAL)
+			myerr = errno;
+			if (myerr == ENOENT || myerr == EINVAL)
 				/* inconsistent with lstat; retry */
 				goto stat_ref;
 			else
@@ -420,14 +420,15 @@
 
 	/* Is it a directory? */
 	if (S_ISDIR(st.st_mode)) {
+		int ignore_errno;
 		/*
 		 * Even though there is a directory where the loose
 		 * ref is supposed to be, there could still be a
 		 * packed ref:
 		 */
-		if (refs_read_raw_ref(refs->packed_ref_store, refname,
-				      oid, referent, type)) {
-			errno = EISDIR;
+		if (refs_read_raw_ref(refs->packed_ref_store, refname, oid,
+				      referent, type, &ignore_errno)) {
+			myerr = EISDIR;
 			goto out;
 		}
 		ret = 0;
@@ -440,7 +441,8 @@
 	 */
 	fd = open(path, O_RDONLY);
 	if (fd < 0) {
-		if (errno == ENOENT && !S_ISLNK(st.st_mode))
+		myerr = errno;
+		if (myerr == ENOENT && !S_ISLNK(st.st_mode))
 			/* inconsistent with lstat; retry */
 			goto stat_ref;
 		else
@@ -448,26 +450,30 @@
 	}
 	strbuf_reset(&sb_contents);
 	if (strbuf_read(&sb_contents, fd, 256) < 0) {
-		int save_errno = errno;
+		myerr = errno;
 		close(fd);
-		errno = save_errno;
 		goto out;
 	}
 	close(fd);
 	strbuf_rtrim(&sb_contents);
 	buf = sb_contents.buf;
 
-	ret = parse_loose_ref_contents(buf, oid, referent, type);
+	ret = parse_loose_ref_contents(buf, oid, referent, type, &myerr);
 
 out:
-	*failure_errno = errno;
+	if (ret && !myerr)
+		BUG("returning non-zero %d, should have set myerr!", ret);
+	*failure_errno = myerr;
+
 	strbuf_release(&sb_path);
 	strbuf_release(&sb_contents);
+	errno = 0;
 	return ret;
 }
 
 int parse_loose_ref_contents(const char *buf, struct object_id *oid,
-			     struct strbuf *referent, unsigned int *type)
+			     struct strbuf *referent, unsigned int *type,
+			     int *failure_errno)
 {
 	const char *p;
 	if (skip_prefix(buf, "ref:", &buf)) {
@@ -486,7 +492,7 @@
 	if (parse_oid_hex(buf, oid, &p) ||
 	    (*p != '\0' && !isspace(*p))) {
 		*type |= REF_ISBROKEN;
-		errno = EINVAL;
+		*failure_errno = EINVAL;
 		return -1;
 	}
 	return 0;
@@ -995,11 +1001,12 @@
  * Locks a ref returning the lock on success and NULL on failure.
  */
 static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
-					   const char *refname, int *type,
+					   const char *refname,
 					   struct strbuf *err)
 {
 	struct strbuf ref_file = STRBUF_INIT;
 	struct ref_lock *lock;
+	int ignore_errno;
 
 	files_assert_main_repository(refs, "lock_ref_oid_basic");
 	assert(err);
@@ -1007,16 +1014,6 @@
 	CALLOC_ARRAY(lock, 1);
 
 	files_ref_path(refs, &ref_file, refname);
-	if (!refs_resolve_ref_unsafe(&refs->base, refname,
-				     RESOLVE_REF_NO_RECURSE,
-				     &lock->old_oid, type)) {
-		if (!refs_verify_refname_available(&refs->base, refname,
-						   NULL, NULL, err))
-			strbuf_addf(err, "unable to resolve reference '%s': %s",
-				    refname, strerror(errno));
-
-		goto error_return;
-	}
 
 	/*
 	 * If the ref did not exist and we are creating it, make sure
@@ -1036,9 +1033,8 @@
 		goto error_return;
 	}
 
-	if (refs_read_ref_full(&refs->base, lock->ref_name,
-			       0,
-			       &lock->old_oid, NULL))
+	if (!refs_resolve_ref_unsafe(&refs->base, lock->ref_name, 0,
+				     &lock->old_oid, NULL, &ignore_errno))
 		oidclr(&lock->old_oid);
 	goto out;
 
@@ -1352,12 +1348,42 @@
 }
 
 static int write_ref_to_lockfile(struct ref_lock *lock,
-				 const struct object_id *oid, struct strbuf *err);
+				 const struct object_id *oid,
+				 int skip_oid_verification, struct strbuf *err);
 static int commit_ref_update(struct files_ref_store *refs,
 			     struct ref_lock *lock,
 			     const struct object_id *oid, const char *logmsg,
 			     struct strbuf *err);
 
+/*
+ * Emit a better error message than lockfile.c's
+ * unable_to_lock_message() would in case there is a D/F conflict with
+ * another existing reference. If there would be a conflict, emit an error
+ * message and return false; otherwise, return true.
+ *
+ * Note that this function is not safe against all races with other
+ * processes, and that's not its job. We'll emit a more verbose error on D/f
+ * conflicts if we get past it into lock_ref_oid_basic().
+ */
+static int refs_rename_ref_available(struct ref_store *refs,
+			      const char *old_refname,
+			      const char *new_refname)
+{
+	struct string_list skip = STRING_LIST_INIT_NODUP;
+	struct strbuf err = STRBUF_INIT;
+	int ok;
+
+	string_list_insert(&skip, old_refname);
+	ok = !refs_verify_refname_available(refs, new_refname,
+					    NULL, &skip, &err);
+	if (!ok)
+		error("%s", err.buf);
+
+	string_list_clear(&skip, 0);
+	strbuf_release(&err);
+	return ok;
+}
+
 static int files_copy_or_rename_ref(struct ref_store *ref_store,
 			    const char *oldrefname, const char *newrefname,
 			    const char *logmsg, int copy)
@@ -1373,6 +1399,7 @@
 	struct strbuf tmp_renamed_log = STRBUF_INIT;
 	int log, ret;
 	struct strbuf err = STRBUF_INIT;
+	int ignore_errno;
 
 	files_reflog_path(refs, &sb_oldref, oldrefname);
 	files_reflog_path(refs, &sb_newref, newrefname);
@@ -1386,7 +1413,7 @@
 
 	if (!refs_resolve_ref_unsafe(&refs->base, oldrefname,
 				     RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
-				&orig_oid, &flag)) {
+				     &orig_oid, &flag, &ignore_errno)) {
 		ret = error("refname %s not found", oldrefname);
 		goto out;
 	}
@@ -1430,9 +1457,9 @@
 	 * the safety anyway; we want to delete the reference whatever
 	 * its current value.
 	 */
-	if (!copy && !refs_read_ref_full(&refs->base, newrefname,
-				RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
-				NULL, NULL) &&
+	if (!copy && refs_resolve_ref_unsafe(&refs->base, newrefname,
+					     RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
+					     NULL, NULL, &ignore_errno) &&
 	    refs_delete_ref(&refs->base, NULL, newrefname,
 			    NULL, REF_NO_DEREF)) {
 		if (errno == EISDIR) {
@@ -1458,7 +1485,7 @@
 
 	logmoved = log;
 
-	lock = lock_ref_oid_basic(refs, newrefname, NULL, &err);
+	lock = lock_ref_oid_basic(refs, newrefname, &err);
 	if (!lock) {
 		if (copy)
 			error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf);
@@ -1469,7 +1496,7 @@
 	}
 	oidcpy(&lock->old_oid, &orig_oid);
 
-	if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
+	if (write_ref_to_lockfile(lock, &orig_oid, 0, &err) ||
 	    commit_ref_update(refs, lock, &orig_oid, logmsg, &err)) {
 		error("unable to write current sha1 into %s: %s", newrefname, err.buf);
 		strbuf_release(&err);
@@ -1480,7 +1507,7 @@
 	goto out;
 
  rollback:
-	lock = lock_ref_oid_basic(refs, oldrefname, NULL, &err);
+	lock = lock_ref_oid_basic(refs, oldrefname, &err);
 	if (!lock) {
 		error("unable to lock %s for rollback: %s", oldrefname, err.buf);
 		strbuf_release(&err);
@@ -1489,7 +1516,7 @@
 
 	flag = log_all_ref_updates;
 	log_all_ref_updates = LOG_REFS_NONE;
-	if (write_ref_to_lockfile(lock, &orig_oid, &err) ||
+	if (write_ref_to_lockfile(lock, &orig_oid, 0, &err) ||
 	    commit_ref_update(refs, lock, &orig_oid, NULL, &err)) {
 		error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
 		strbuf_release(&err);
@@ -1639,15 +1666,14 @@
 	return -1;
 }
 
-static int files_create_reflog(struct ref_store *ref_store,
-			       const char *refname, int force_create,
+static int files_create_reflog(struct ref_store *ref_store, const char *refname,
 			       struct strbuf *err)
 {
 	struct files_ref_store *refs =
 		files_downcast(ref_store, REF_STORE_WRITE, "create_reflog");
 	int fd;
 
-	if (log_ref_setup(refs, refname, force_create, &fd, err))
+	if (log_ref_setup(refs, refname, 1, &fd, err))
 		return -1;
 
 	if (fd >= 0)
@@ -1725,26 +1751,31 @@
  * errors, rollback the lockfile, fill in *err and return -1.
  */
 static int write_ref_to_lockfile(struct ref_lock *lock,
-				 const struct object_id *oid, struct strbuf *err)
+				 const struct object_id *oid,
+				 int skip_oid_verification, struct strbuf *err)
 {
 	static char term = '\n';
 	struct object *o;
 	int fd;
 
-	o = parse_object(the_repository, oid);
-	if (!o) {
-		strbuf_addf(err,
-			    "trying to write ref '%s' with nonexistent object %s",
-			    lock->ref_name, oid_to_hex(oid));
-		unlock_ref(lock);
-		return -1;
-	}
-	if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
-		strbuf_addf(err,
-			    "trying to write non-commit object %s to branch '%s'",
-			    oid_to_hex(oid), lock->ref_name);
-		unlock_ref(lock);
-		return -1;
+	if (!skip_oid_verification) {
+		o = parse_object(the_repository, oid);
+		if (!o) {
+			strbuf_addf(
+				err,
+				"trying to write ref '%s' with nonexistent object %s",
+				lock->ref_name, oid_to_hex(oid));
+			unlock_ref(lock);
+			return -1;
+		}
+		if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
+			strbuf_addf(
+				err,
+				"trying to write non-commit object %s to branch '%s'",
+				oid_to_hex(oid), lock->ref_name);
+			unlock_ref(lock);
+			return -1;
+		}
 	}
 	fd = get_lock_file_fd(&lock->lk);
 	if (write_in_full(fd, oid_to_hex(oid), the_hash_algo->hexsz) < 0 ||
@@ -1797,10 +1828,12 @@
 		 */
 		int head_flag;
 		const char *head_ref;
+		int ignore_errno;
 
 		head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
 						   RESOLVE_REF_READING,
-						   NULL, &head_flag);
+						   NULL, &head_flag,
+						   &ignore_errno);
 		if (head_ref && (head_flag & REF_ISSYMREF) &&
 		    !strcmp(head_ref, lock->ref_name)) {
 			struct strbuf log_err = STRBUF_INIT;
@@ -1844,9 +1877,12 @@
 {
 	struct strbuf err = STRBUF_INIT;
 	struct object_id new_oid;
+	int ignore_errno;
+
 	if (logmsg &&
-	    !refs_read_ref_full(&refs->base, target,
-				RESOLVE_REF_READING, &new_oid, NULL) &&
+	    refs_resolve_ref_unsafe(&refs->base, target,
+				    RESOLVE_REF_READING, &new_oid, NULL,
+				    &ignore_errno) &&
 	    files_log_ref_write(refs, refname, &lock->old_oid,
 				&new_oid, logmsg, 0, &err)) {
 		error("%s", err.buf);
@@ -1887,7 +1923,7 @@
 	struct ref_lock *lock;
 	int ret;
 
-	lock = lock_ref_oid_basic(refs, refname, NULL, &err);
+	lock = lock_ref_oid_basic(refs, refname, &err);
 	if (!lock) {
 		error("%s", err.buf);
 		strbuf_release(&err);
@@ -2120,6 +2156,7 @@
 		(struct files_reflog_iterator *)ref_iterator;
 	struct dir_iterator *diter = iter->dir_iterator;
 	int ok;
+	int ignore_errno;
 
 	while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
 		int flags;
@@ -2131,9 +2168,10 @@
 		if (ends_with(diter->basename, ".lock"))
 			continue;
 
-		if (refs_read_ref_full(iter->ref_store,
-				       diter->relative_path, 0,
-				       &iter->oid, &flags)) {
+		if (!refs_resolve_ref_unsafe(iter->ref_store,
+					     diter->relative_path, 0,
+					     &iter->oid, &flags,
+					     &ignore_errno)) {
 			error("bad ref for %s", diter->path.buf);
 			continue;
 		}
@@ -2151,7 +2189,7 @@
 }
 
 static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
-				   struct object_id *peeled)
+				      struct object_id *peeled)
 {
 	BUG("ref_iterator_peel() called for reflog_iterator");
 }
@@ -2477,9 +2515,11 @@
 			 * the transaction, so we have to read it here
 			 * to record and possibly check old_oid:
 			 */
-			if (refs_read_ref_full(&refs->base,
-					       referent.buf, 0,
-					       &lock->old_oid, NULL)) {
+			int ignore_errno;
+			if (!refs_resolve_ref_unsafe(&refs->base,
+						     referent.buf, 0,
+						     &lock->old_oid, NULL,
+						     &ignore_errno)) {
 				if (update->flags & REF_HAVE_OLD) {
 					strbuf_addf(err, "cannot lock ref '%s': "
 						    "error reading reference",
@@ -2535,8 +2575,10 @@
 			 * The reference already has the desired
 			 * value, so we don't need to write it.
 			 */
-		} else if (write_ref_to_lockfile(lock, &update->new_oid,
-						 err)) {
+		} else if (write_ref_to_lockfile(
+				   lock, &update->new_oid,
+				   update->flags & REF_SKIP_OID_VERIFICATION,
+				   err)) {
 			char *write_err = strbuf_detach(err, NULL);
 
 			/*
@@ -3039,11 +3081,12 @@
 }
 
 struct expire_reflog_cb {
-	unsigned int flags;
 	reflog_expiry_should_prune_fn *should_prune_fn;
 	void *policy_cb;
 	FILE *newlog;
 	struct object_id last_kept_oid;
+	unsigned int rewrite:1,
+		     dry_run:1;
 };
 
 static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
@@ -3051,33 +3094,27 @@
 			     const char *message, void *cb_data)
 {
 	struct expire_reflog_cb *cb = cb_data;
-	struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
+	reflog_expiry_should_prune_fn *fn = cb->should_prune_fn;
 
-	if (cb->flags & EXPIRE_REFLOGS_REWRITE)
+	if (cb->rewrite)
 		ooid = &cb->last_kept_oid;
 
-	if ((*cb->should_prune_fn)(ooid, noid, email, timestamp, tz,
-				   message, policy_cb)) {
-		if (!cb->newlog)
-			printf("would prune %s", message);
-		else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
-			printf("prune %s", message);
-	} else {
-		if (cb->newlog) {
-			fprintf(cb->newlog, "%s %s %s %"PRItime" %+05d\t%s",
-				oid_to_hex(ooid), oid_to_hex(noid),
-				email, timestamp, tz, message);
-			oidcpy(&cb->last_kept_oid, noid);
-		}
-		if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
-			printf("keep %s", message);
-	}
+	if (fn(ooid, noid, email, timestamp, tz, message, cb->policy_cb))
+		return 0;
+
+	if (cb->dry_run)
+		return 0; /* --dry-run */
+
+	fprintf(cb->newlog, "%s %s %s %"PRItime" %+05d\t%s", oid_to_hex(ooid),
+		oid_to_hex(noid), email, timestamp, tz, message);
+	oidcpy(&cb->last_kept_oid, noid);
+
 	return 0;
 }
 
 static int files_reflog_expire(struct ref_store *ref_store,
 			       const char *refname,
-			       unsigned int flags,
+			       unsigned int expire_flags,
 			       reflog_expiry_prepare_fn prepare_fn,
 			       reflog_expiry_should_prune_fn should_prune_fn,
 			       reflog_expiry_cleanup_fn cleanup_fn,
@@ -3091,12 +3128,12 @@
 	struct strbuf log_file_sb = STRBUF_INIT;
 	char *log_file;
 	int status = 0;
-	int type;
 	struct strbuf err = STRBUF_INIT;
 	const struct object_id *oid;
 
 	memset(&cb, 0, sizeof(cb));
-	cb.flags = flags;
+	cb.rewrite = !!(expire_flags & EXPIRE_REFLOGS_REWRITE);
+	cb.dry_run = !!(expire_flags & EXPIRE_REFLOGS_DRY_RUN);
 	cb.policy_cb = policy_cb_data;
 	cb.should_prune_fn = should_prune_fn;
 
@@ -3105,7 +3142,7 @@
 	 * reference itself, plus we might need to update the
 	 * reference if --updateref was specified:
 	 */
-	lock = lock_ref_oid_basic(refs, refname, &type, &err);
+	lock = lock_ref_oid_basic(refs, refname, &err);
 	if (!lock) {
 		error("cannot lock ref '%s': %s", refname, err.buf);
 		strbuf_release(&err);
@@ -3132,7 +3169,7 @@
 
 	files_reflog_path(refs, &log_file_sb, refname);
 	log_file = strbuf_detach(&log_file_sb, NULL);
-	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
+	if (!cb.dry_run) {
 		/*
 		 * Even though holding $GIT_DIR/logs/$reflog.lock has
 		 * no locking implications, we use the lock_file
@@ -3159,7 +3196,7 @@
 	refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb);
 	(*cleanup_fn)(cb.policy_cb);
 
-	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
+	if (!cb.dry_run) {
 		/*
 		 * It doesn't make sense to adjust a reference pointed
 		 * to by a symbolic ref based on expiring entries in
@@ -3167,9 +3204,20 @@
 		 * a reference if there are no remaining reflog
 		 * entries.
 		 */
-		int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
-			!(type & REF_ISSYMREF) &&
-			!is_null_oid(&cb.last_kept_oid);
+		int update = 0;
+
+		if ((expire_flags & EXPIRE_REFLOGS_UPDATE_REF) &&
+		    !is_null_oid(&cb.last_kept_oid)) {
+			int ignore_errno;
+			int type;
+			const char *ref;
+
+			ref = refs_resolve_ref_unsafe(&refs->base, refname,
+						      RESOLVE_REF_NO_RECURSE,
+						      NULL, &type,
+						      &ignore_errno);
+			update = !!(ref && !(type & REF_ISSYMREF));
+		}
 
 		if (close_lock_file_gently(&reflog_lock)) {
 			status |= error("couldn't write %s: %s", log_file,
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index 1c5211b..d91a201 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -194,20 +194,19 @@
 }
 
 struct ref_store *packed_ref_store_create(struct repository *repo,
-					  const char *path,
+					  const char *gitdir,
 					  unsigned int store_flags)
 {
 	struct packed_ref_store *refs = xcalloc(1, sizeof(*refs));
 	struct ref_store *ref_store = (struct ref_store *)refs;
+	struct strbuf sb = STRBUF_INIT;
 
-	base_ref_store_init(ref_store, &refs_be_packed);
-	ref_store->repo = repo;
-	ref_store->gitdir = xstrdup(path);
+	base_ref_store_init(ref_store, repo, gitdir, &refs_be_packed);
 	refs->store_flags = store_flags;
 
-	refs->path = xstrdup(path);
+	strbuf_addf(&sb, "%s/packed-refs", gitdir);
+	refs->path = strbuf_detach(&sb, NULL);
 	chdir_notify_reparent("packed-refs", &refs->path);
-
 	return ref_store;
 }
 
@@ -1354,6 +1353,7 @@
 	ret = 0;
 	for (i = 0; i < transaction->nr; i++) {
 		struct ref_update *update = transaction->updates[i];
+		int failure_errno;
 		unsigned int type;
 		struct object_id oid;
 
@@ -1364,9 +1364,9 @@
 			 */
 			continue;
 
-		if (!refs_read_raw_ref(ref_store, update->refname,
-				       &oid, &referent, &type) ||
-		    errno != ENOENT) {
+		if (!refs_read_raw_ref(ref_store, update->refname, &oid,
+				       &referent, &type, &failure_errno) ||
+		    failure_errno != ENOENT) {
 			/*
 			 * We have to actually delete that reference
 			 * -> this transaction is needed.
@@ -1628,8 +1628,7 @@
 }
 
 static int packed_create_reflog(struct ref_store *ref_store,
-			       const char *refname, int force_create,
-			       struct strbuf *err)
+				const char *refname, struct strbuf *err)
 {
 	BUG("packed reference store does not support reflogs");
 }
diff --git a/refs/packed-backend.h b/refs/packed-backend.h
index f61a73e..9dd8a34 100644
--- a/refs/packed-backend.h
+++ b/refs/packed-backend.h
@@ -14,7 +14,7 @@
  */
 
 struct ref_store *packed_ref_store_create(struct repository *repo,
-					  const char *path,
+					  const char *gitdir,
 					  unsigned int store_flags);
 
 /*
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index 1222474..7ff6fba 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -150,9 +150,9 @@
 	const char refname[FLEX_ARRAY];
 };
 
-int refs_read_raw_ref(struct ref_store *ref_store,
-		      const char *refname, struct object_id *oid,
-		      struct strbuf *referent, unsigned int *type);
+int refs_read_raw_ref(struct ref_store *ref_store, const char *refname,
+		      struct object_id *oid, struct strbuf *referent,
+		      unsigned int *type, int *failure_errno);
 
 /*
  * Write an error to `err` and return a nonzero value iff the same
@@ -229,20 +229,6 @@
 				const struct string_list *extras,
 				const struct string_list *skip);
 
-/*
- * Check whether an attempt to rename old_refname to new_refname would
- * cause a D/F conflict with any existing reference (other than
- * possibly old_refname). If there would be a conflict, emit an error
- * message and return false; otherwise, return true.
- *
- * Note that this function is not safe against all races with other
- * processes (though rename_ref() catches some races that might get by
- * this check).
- */
-int refs_rename_ref_available(struct ref_store *refs,
-			      const char *old_refname,
-			      const char *new_refname);
-
 /* We allow "recursive" symbolic refs. Only within reason, though */
 #define SYMREF_MAXDEPTH 5
 
@@ -606,7 +592,7 @@
 					   void *cb_data);
 typedef int reflog_exists_fn(struct ref_store *ref_store, const char *refname);
 typedef int create_reflog_fn(struct ref_store *ref_store, const char *refname,
-			     int force_create, struct strbuf *err);
+			     struct strbuf *err);
 typedef int delete_reflog_fn(struct ref_store *ref_store, const char *refname);
 typedef int reflog_expire_fn(struct ref_store *ref_store,
 			     const char *refname,
@@ -713,17 +699,19 @@
 };
 
 /*
- * Parse contents of a loose ref file.
+ * Parse contents of a loose ref file. *failure_errno maybe be set to EINVAL for
+ * invalid contents.
  */
 int parse_loose_ref_contents(const char *buf, struct object_id *oid,
-			     struct strbuf *referent, unsigned int *type);
+			     struct strbuf *referent, unsigned int *type,
+			     int *failure_errno);
 
 /*
  * Fill in the generic part of refs and add it to our collection of
  * reference stores.
  */
-void base_ref_store_init(struct ref_store *refs,
-			 const struct ref_storage_be *be);
+void base_ref_store_init(struct ref_store *refs, struct repository *repo,
+			 const char *path, const struct ref_storage_be *be);
 
 /*
  * Support GIT_TRACE_REFS by optionally wrapping the given ref_store instance.
diff --git a/reftable/LICENSE b/reftable/LICENSE
new file mode 100644
index 0000000..402e0f9
--- /dev/null
+++ b/reftable/LICENSE
@@ -0,0 +1,31 @@
+BSD License
+
+Copyright (c) 2020, Google LLC
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+* Redistributions of source code must retain the above copyright notice,
+this list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+* Neither the name of Google LLC nor the names of its contributors may
+be used to endorse or promote products derived from this software
+without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/reftable/basics.c b/reftable/basics.c
new file mode 100644
index 0000000..f761e48
--- /dev/null
+++ b/reftable/basics.c
@@ -0,0 +1,128 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "basics.h"
+
+void put_be24(uint8_t *out, uint32_t i)
+{
+	out[0] = (uint8_t)((i >> 16) & 0xff);
+	out[1] = (uint8_t)((i >> 8) & 0xff);
+	out[2] = (uint8_t)(i & 0xff);
+}
+
+uint32_t get_be24(uint8_t *in)
+{
+	return (uint32_t)(in[0]) << 16 | (uint32_t)(in[1]) << 8 |
+	       (uint32_t)(in[2]);
+}
+
+void put_be16(uint8_t *out, uint16_t i)
+{
+	out[0] = (uint8_t)((i >> 8) & 0xff);
+	out[1] = (uint8_t)(i & 0xff);
+}
+
+int binsearch(size_t sz, int (*f)(size_t k, void *args), void *args)
+{
+	size_t lo = 0;
+	size_t hi = sz;
+
+	/* Invariants:
+	 *
+	 *  (hi == sz) || f(hi) == true
+	 *  (lo == 0 && f(0) == true) || fi(lo) == false
+	 */
+	while (hi - lo > 1) {
+		size_t mid = lo + (hi - lo) / 2;
+
+		if (f(mid, args))
+			hi = mid;
+		else
+			lo = mid;
+	}
+
+	if (lo)
+		return hi;
+
+	return f(0, args) ? 0 : 1;
+}
+
+void free_names(char **a)
+{
+	char **p;
+	if (!a) {
+		return;
+	}
+	for (p = a; *p; p++) {
+		reftable_free(*p);
+	}
+	reftable_free(a);
+}
+
+int names_length(char **names)
+{
+	char **p = names;
+	for (; *p; p++) {
+		/* empty */
+	}
+	return p - names;
+}
+
+void parse_names(char *buf, int size, char ***namesp)
+{
+	char **names = NULL;
+	size_t names_cap = 0;
+	size_t names_len = 0;
+
+	char *p = buf;
+	char *end = buf + size;
+	while (p < end) {
+		char *next = strchr(p, '\n');
+		if (next && next < end) {
+			*next = 0;
+		} else {
+			next = end;
+		}
+		if (p < next) {
+			if (names_len == names_cap) {
+				names_cap = 2 * names_cap + 1;
+				names = reftable_realloc(
+					names, names_cap * sizeof(*names));
+			}
+			names[names_len++] = xstrdup(p);
+		}
+		p = next + 1;
+	}
+
+	names = reftable_realloc(names, (names_len + 1) * sizeof(*names));
+	names[names_len] = NULL;
+	*namesp = names;
+}
+
+int names_equal(char **a, char **b)
+{
+	int i = 0;
+	for (; a[i] && b[i]; i++) {
+		if (strcmp(a[i], b[i])) {
+			return 0;
+		}
+	}
+
+	return a[i] == b[i];
+}
+
+int common_prefix_size(struct strbuf *a, struct strbuf *b)
+{
+	int p = 0;
+	for (; p < a->len && p < b->len; p++) {
+		if (a->buf[p] != b->buf[p])
+			break;
+	}
+
+	return p;
+}
diff --git a/reftable/basics.h b/reftable/basics.h
new file mode 100644
index 0000000..096b368
--- /dev/null
+++ b/reftable/basics.h
@@ -0,0 +1,60 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef BASICS_H
+#define BASICS_H
+
+/*
+ * miscellaneous utilities that are not provided by Git.
+ */
+
+#include "system.h"
+
+/* Bigendian en/decoding of integers */
+
+void put_be24(uint8_t *out, uint32_t i);
+uint32_t get_be24(uint8_t *in);
+void put_be16(uint8_t *out, uint16_t i);
+
+/*
+ * find smallest index i in [0, sz) at which f(i) is true, assuming
+ * that f is ascending. Return sz if f(i) is false for all indices.
+ *
+ * Contrary to bsearch(3), this returns something useful if the argument is not
+ * found.
+ */
+int binsearch(size_t sz, int (*f)(size_t k, void *args), void *args);
+
+/*
+ * Frees a NULL terminated array of malloced strings. The array itself is also
+ * freed.
+ */
+void free_names(char **a);
+
+/* parse a newline separated list of names. `size` is the length of the buffer,
+ * without terminating '\0'. Empty names are discarded. */
+void parse_names(char *buf, int size, char ***namesp);
+
+/* compares two NULL-terminated arrays of strings. */
+int names_equal(char **a, char **b);
+
+/* returns the array size of a NULL-terminated array of strings. */
+int names_length(char **names);
+
+/* Allocation routines; they invoke the functions set through
+ * reftable_set_alloc() */
+void *reftable_malloc(size_t sz);
+void *reftable_realloc(void *p, size_t sz);
+void reftable_free(void *p);
+void *reftable_calloc(size_t sz);
+
+/* Find the longest shared prefix size of `a` and `b` */
+struct strbuf;
+int common_prefix_size(struct strbuf *a, struct strbuf *b);
+
+#endif
diff --git a/reftable/basics_test.c b/reftable/basics_test.c
new file mode 100644
index 0000000..1fcd229
--- /dev/null
+++ b/reftable/basics_test.c
@@ -0,0 +1,98 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "system.h"
+
+#include "basics.h"
+#include "test_framework.h"
+#include "reftable-tests.h"
+
+struct binsearch_args {
+	int key;
+	int *arr;
+};
+
+static int binsearch_func(size_t i, void *void_args)
+{
+	struct binsearch_args *args = void_args;
+
+	return args->key < args->arr[i];
+}
+
+static void test_binsearch(void)
+{
+	int arr[] = { 2, 4, 6, 8, 10 };
+	size_t sz = ARRAY_SIZE(arr);
+	struct binsearch_args args = {
+		.arr = arr,
+	};
+
+	int i = 0;
+	for (i = 1; i < 11; i++) {
+		int res;
+		args.key = i;
+		res = binsearch(sz, &binsearch_func, &args);
+
+		if (res < sz) {
+			EXPECT(args.key < arr[res]);
+			if (res > 0) {
+				EXPECT(args.key >= arr[res - 1]);
+			}
+		} else {
+			EXPECT(args.key == 10 || args.key == 11);
+		}
+	}
+}
+
+static void test_names_length(void)
+{
+	char *a[] = { "a", "b", NULL };
+	EXPECT(names_length(a) == 2);
+}
+
+static void test_parse_names_normal(void)
+{
+	char in[] = "a\nb\n";
+	char **out = NULL;
+	parse_names(in, strlen(in), &out);
+	EXPECT(!strcmp(out[0], "a"));
+	EXPECT(!strcmp(out[1], "b"));
+	EXPECT(!out[2]);
+	free_names(out);
+}
+
+static void test_parse_names_drop_empty(void)
+{
+	char in[] = "a\n\n";
+	char **out = NULL;
+	parse_names(in, strlen(in), &out);
+	EXPECT(!strcmp(out[0], "a"));
+	EXPECT(!out[1]);
+	free_names(out);
+}
+
+static void test_common_prefix(void)
+{
+	struct strbuf s1 = STRBUF_INIT;
+	struct strbuf s2 = STRBUF_INIT;
+	strbuf_addstr(&s1, "abcdef");
+	strbuf_addstr(&s2, "abc");
+	EXPECT(common_prefix_size(&s1, &s2) == 3);
+	strbuf_release(&s1);
+	strbuf_release(&s2);
+}
+
+int basics_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_common_prefix);
+	RUN_TEST(test_parse_names_normal);
+	RUN_TEST(test_parse_names_drop_empty);
+	RUN_TEST(test_binsearch);
+	RUN_TEST(test_names_length);
+	return 0;
+}
diff --git a/reftable/block.c b/reftable/block.c
new file mode 100644
index 0000000..855e3f5
--- /dev/null
+++ b/reftable/block.c
@@ -0,0 +1,437 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "block.h"
+
+#include "blocksource.h"
+#include "constants.h"
+#include "record.h"
+#include "reftable-error.h"
+#include "system.h"
+#include <zlib.h>
+
+int header_size(int version)
+{
+	switch (version) {
+	case 1:
+		return 24;
+	case 2:
+		return 28;
+	}
+	abort();
+}
+
+int footer_size(int version)
+{
+	switch (version) {
+	case 1:
+		return 68;
+	case 2:
+		return 72;
+	}
+	abort();
+}
+
+static int block_writer_register_restart(struct block_writer *w, int n,
+					 int is_restart, struct strbuf *key)
+{
+	int rlen = w->restart_len;
+	if (rlen >= MAX_RESTARTS) {
+		is_restart = 0;
+	}
+
+	if (is_restart) {
+		rlen++;
+	}
+	if (2 + 3 * rlen + n > w->block_size - w->next)
+		return -1;
+	if (is_restart) {
+		if (w->restart_len == w->restart_cap) {
+			w->restart_cap = w->restart_cap * 2 + 1;
+			w->restarts = reftable_realloc(
+				w->restarts, sizeof(uint32_t) * w->restart_cap);
+		}
+
+		w->restarts[w->restart_len++] = w->next;
+	}
+
+	w->next += n;
+
+	strbuf_reset(&w->last_key);
+	strbuf_addbuf(&w->last_key, key);
+	w->entries++;
+	return 0;
+}
+
+void block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *buf,
+		       uint32_t block_size, uint32_t header_off, int hash_size)
+{
+	bw->buf = buf;
+	bw->hash_size = hash_size;
+	bw->block_size = block_size;
+	bw->header_off = header_off;
+	bw->buf[header_off] = typ;
+	bw->next = header_off + 4;
+	bw->restart_interval = 16;
+	bw->entries = 0;
+	bw->restart_len = 0;
+	bw->last_key.len = 0;
+}
+
+uint8_t block_writer_type(struct block_writer *bw)
+{
+	return bw->buf[bw->header_off];
+}
+
+/* adds the reftable_record to the block. Returns -1 if it does not fit, 0 on
+   success */
+int block_writer_add(struct block_writer *w, struct reftable_record *rec)
+{
+	struct strbuf empty = STRBUF_INIT;
+	struct strbuf last =
+		w->entries % w->restart_interval == 0 ? empty : w->last_key;
+	struct string_view out = {
+		.buf = w->buf + w->next,
+		.len = w->block_size - w->next,
+	};
+
+	struct string_view start = out;
+
+	int is_restart = 0;
+	struct strbuf key = STRBUF_INIT;
+	int n = 0;
+
+	reftable_record_key(rec, &key);
+	n = reftable_encode_key(&is_restart, out, last, key,
+				reftable_record_val_type(rec));
+	if (n < 0)
+		goto done;
+	string_view_consume(&out, n);
+
+	n = reftable_record_encode(rec, out, w->hash_size);
+	if (n < 0)
+		goto done;
+	string_view_consume(&out, n);
+
+	if (block_writer_register_restart(w, start.len - out.len, is_restart,
+					  &key) < 0)
+		goto done;
+
+	strbuf_release(&key);
+	return 0;
+
+done:
+	strbuf_release(&key);
+	return -1;
+}
+
+int block_writer_finish(struct block_writer *w)
+{
+	int i;
+	for (i = 0; i < w->restart_len; i++) {
+		put_be24(w->buf + w->next, w->restarts[i]);
+		w->next += 3;
+	}
+
+	put_be16(w->buf + w->next, w->restart_len);
+	w->next += 2;
+	put_be24(w->buf + 1 + w->header_off, w->next);
+
+	if (block_writer_type(w) == BLOCK_TYPE_LOG) {
+		int block_header_skip = 4 + w->header_off;
+		uLongf src_len = w->next - block_header_skip;
+		uLongf dest_cap = src_len * 1.001 + 12;
+
+		uint8_t *compressed = reftable_malloc(dest_cap);
+		while (1) {
+			uLongf out_dest_len = dest_cap;
+			int zresult = compress2(compressed, &out_dest_len,
+						w->buf + block_header_skip,
+						src_len, 9);
+			if (zresult == Z_BUF_ERROR && dest_cap < LONG_MAX) {
+				dest_cap *= 2;
+				compressed =
+					reftable_realloc(compressed, dest_cap);
+				if (compressed)
+					continue;
+			}
+
+			if (Z_OK != zresult) {
+				reftable_free(compressed);
+				return REFTABLE_ZLIB_ERROR;
+			}
+
+			memcpy(w->buf + block_header_skip, compressed,
+			       out_dest_len);
+			w->next = out_dest_len + block_header_skip;
+			reftable_free(compressed);
+			break;
+		}
+	}
+	return w->next;
+}
+
+uint8_t block_reader_type(struct block_reader *r)
+{
+	return r->block.data[r->header_off];
+}
+
+int block_reader_init(struct block_reader *br, struct reftable_block *block,
+		      uint32_t header_off, uint32_t table_block_size,
+		      int hash_size)
+{
+	uint32_t full_block_size = table_block_size;
+	uint8_t typ = block->data[header_off];
+	uint32_t sz = get_be24(block->data + header_off + 1);
+
+	uint16_t restart_count = 0;
+	uint32_t restart_start = 0;
+	uint8_t *restart_bytes = NULL;
+
+	if (!reftable_is_block_type(typ))
+		return REFTABLE_FORMAT_ERROR;
+
+	if (typ == BLOCK_TYPE_LOG) {
+		int block_header_skip = 4 + header_off;
+		uLongf dst_len = sz - block_header_skip; /* total size of dest
+							    buffer. */
+		uLongf src_len = block->len - block_header_skip;
+		/* Log blocks specify the *uncompressed* size in their header.
+		 */
+		uint8_t *uncompressed = reftable_malloc(sz);
+
+		/* Copy over the block header verbatim. It's not compressed. */
+		memcpy(uncompressed, block->data, block_header_skip);
+
+		/* Uncompress */
+		if (Z_OK !=
+		    uncompress2(uncompressed + block_header_skip, &dst_len,
+				block->data + block_header_skip, &src_len)) {
+			reftable_free(uncompressed);
+			return REFTABLE_ZLIB_ERROR;
+		}
+
+		if (dst_len + block_header_skip != sz)
+			return REFTABLE_FORMAT_ERROR;
+
+		/* We're done with the input data. */
+		reftable_block_done(block);
+		block->data = uncompressed;
+		block->len = sz;
+		block->source = malloc_block_source();
+		full_block_size = src_len + block_header_skip;
+	} else if (full_block_size == 0) {
+		full_block_size = sz;
+	} else if (sz < full_block_size && sz < block->len &&
+		   block->data[sz] != 0) {
+		/* If the block is smaller than the full block size, it is
+		   padded (data followed by '\0') or the next block is
+		   unaligned. */
+		full_block_size = sz;
+	}
+
+	restart_count = get_be16(block->data + sz - 2);
+	restart_start = sz - 2 - 3 * restart_count;
+	restart_bytes = block->data + restart_start;
+
+	/* transfer ownership. */
+	br->block = *block;
+	block->data = NULL;
+	block->len = 0;
+
+	br->hash_size = hash_size;
+	br->block_len = restart_start;
+	br->full_block_size = full_block_size;
+	br->header_off = header_off;
+	br->restart_count = restart_count;
+	br->restart_bytes = restart_bytes;
+
+	return 0;
+}
+
+static uint32_t block_reader_restart_offset(struct block_reader *br, int i)
+{
+	return get_be24(br->restart_bytes + 3 * i);
+}
+
+void block_reader_start(struct block_reader *br, struct block_iter *it)
+{
+	it->br = br;
+	strbuf_reset(&it->last_key);
+	it->next_off = br->header_off + 4;
+}
+
+struct restart_find_args {
+	int error;
+	struct strbuf key;
+	struct block_reader *r;
+};
+
+static int restart_key_less(size_t idx, void *args)
+{
+	struct restart_find_args *a = args;
+	uint32_t off = block_reader_restart_offset(a->r, idx);
+	struct string_view in = {
+		.buf = a->r->block.data + off,
+		.len = a->r->block_len - off,
+	};
+
+	/* the restart key is verbatim in the block, so this could avoid the
+	   alloc for decoding the key */
+	struct strbuf rkey = STRBUF_INIT;
+	struct strbuf last_key = STRBUF_INIT;
+	uint8_t unused_extra;
+	int n = reftable_decode_key(&rkey, &unused_extra, last_key, in);
+	int result;
+	if (n < 0) {
+		a->error = 1;
+		return -1;
+	}
+
+	result = strbuf_cmp(&a->key, &rkey);
+	strbuf_release(&rkey);
+	return result;
+}
+
+void block_iter_copy_from(struct block_iter *dest, struct block_iter *src)
+{
+	dest->br = src->br;
+	dest->next_off = src->next_off;
+	strbuf_reset(&dest->last_key);
+	strbuf_addbuf(&dest->last_key, &src->last_key);
+}
+
+int block_iter_next(struct block_iter *it, struct reftable_record *rec)
+{
+	struct string_view in = {
+		.buf = it->br->block.data + it->next_off,
+		.len = it->br->block_len - it->next_off,
+	};
+	struct string_view start = in;
+	struct strbuf key = STRBUF_INIT;
+	uint8_t extra = 0;
+	int n = 0;
+
+	if (it->next_off >= it->br->block_len)
+		return 1;
+
+	n = reftable_decode_key(&key, &extra, it->last_key, in);
+	if (n < 0)
+		return -1;
+
+	string_view_consume(&in, n);
+	n = reftable_record_decode(rec, key, extra, in, it->br->hash_size);
+	if (n < 0)
+		return -1;
+	string_view_consume(&in, n);
+
+	strbuf_reset(&it->last_key);
+	strbuf_addbuf(&it->last_key, &key);
+	it->next_off += start.len - in.len;
+	strbuf_release(&key);
+	return 0;
+}
+
+int block_reader_first_key(struct block_reader *br, struct strbuf *key)
+{
+	struct strbuf empty = STRBUF_INIT;
+	int off = br->header_off + 4;
+	struct string_view in = {
+		.buf = br->block.data + off,
+		.len = br->block_len - off,
+	};
+
+	uint8_t extra = 0;
+	int n = reftable_decode_key(key, &extra, empty, in);
+	if (n < 0)
+		return n;
+
+	return 0;
+}
+
+int block_iter_seek(struct block_iter *it, struct strbuf *want)
+{
+	return block_reader_seek(it->br, it, want);
+}
+
+void block_iter_close(struct block_iter *it)
+{
+	strbuf_release(&it->last_key);
+}
+
+int block_reader_seek(struct block_reader *br, struct block_iter *it,
+		      struct strbuf *want)
+{
+	struct restart_find_args args = {
+		.key = *want,
+		.r = br,
+	};
+	struct reftable_record rec = reftable_new_record(block_reader_type(br));
+	struct strbuf key = STRBUF_INIT;
+	int err = 0;
+	struct block_iter next = {
+		.last_key = STRBUF_INIT,
+	};
+
+	int i = binsearch(br->restart_count, &restart_key_less, &args);
+	if (args.error) {
+		err = REFTABLE_FORMAT_ERROR;
+		goto done;
+	}
+
+	it->br = br;
+	if (i > 0) {
+		i--;
+		it->next_off = block_reader_restart_offset(br, i);
+	} else {
+		it->next_off = br->header_off + 4;
+	}
+
+	/* We're looking for the last entry less/equal than the wanted key, so
+	   we have to go one entry too far and then back up.
+	*/
+	while (1) {
+		block_iter_copy_from(&next, it);
+		err = block_iter_next(&next, &rec);
+		if (err < 0)
+			goto done;
+
+		reftable_record_key(&rec, &key);
+		if (err > 0 || strbuf_cmp(&key, want) >= 0) {
+			err = 0;
+			goto done;
+		}
+
+		block_iter_copy_from(it, &next);
+	}
+
+done:
+	strbuf_release(&key);
+	strbuf_release(&next.last_key);
+	reftable_record_destroy(&rec);
+
+	return err;
+}
+
+void block_writer_release(struct block_writer *bw)
+{
+	FREE_AND_NULL(bw->restarts);
+	strbuf_release(&bw->last_key);
+	/* the block is not owned. */
+}
+
+void reftable_block_done(struct reftable_block *blockp)
+{
+	struct reftable_block_source source = blockp->source;
+	if (blockp && source.ops)
+		source.ops->return_block(source.arg, blockp);
+	blockp->data = NULL;
+	blockp->len = 0;
+	blockp->source.ops = NULL;
+	blockp->source.arg = NULL;
+}
diff --git a/reftable/block.h b/reftable/block.h
new file mode 100644
index 0000000..87c7753
--- /dev/null
+++ b/reftable/block.h
@@ -0,0 +1,127 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef BLOCK_H
+#define BLOCK_H
+
+#include "basics.h"
+#include "record.h"
+#include "reftable-blocksource.h"
+
+/*
+ * Writes reftable blocks. The block_writer is reused across blocks to minimize
+ * allocation overhead.
+ */
+struct block_writer {
+	uint8_t *buf;
+	uint32_t block_size;
+
+	/* Offset of the global header. Nonzero in the first block only. */
+	uint32_t header_off;
+
+	/* How often to restart keys. */
+	int restart_interval;
+	int hash_size;
+
+	/* Offset of next uint8_t to write. */
+	uint32_t next;
+	uint32_t *restarts;
+	uint32_t restart_len;
+	uint32_t restart_cap;
+
+	struct strbuf last_key;
+	int entries;
+};
+
+/*
+ * initializes the blockwriter to write `typ` entries, using `buf` as temporary
+ * storage. `buf` is not owned by the block_writer. */
+void block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *buf,
+		       uint32_t block_size, uint32_t header_off, int hash_size);
+
+/* returns the block type (eg. 'r' for ref records. */
+uint8_t block_writer_type(struct block_writer *bw);
+
+/* appends the record, or -1 if it doesn't fit. */
+int block_writer_add(struct block_writer *w, struct reftable_record *rec);
+
+/* appends the key restarts, and compress the block if necessary. */
+int block_writer_finish(struct block_writer *w);
+
+/* clears out internally allocated block_writer members. */
+void block_writer_release(struct block_writer *bw);
+
+/* Read a block. */
+struct block_reader {
+	/* offset of the block header; nonzero for the first block in a
+	 * reftable. */
+	uint32_t header_off;
+
+	/* the memory block */
+	struct reftable_block block;
+	int hash_size;
+
+	/* size of the data, excluding restart data. */
+	uint32_t block_len;
+	uint8_t *restart_bytes;
+	uint16_t restart_count;
+
+	/* size of the data in the file. For log blocks, this is the compressed
+	 * size. */
+	uint32_t full_block_size;
+};
+
+/* Iterate over entries in a block */
+struct block_iter {
+	/* offset within the block of the next entry to read. */
+	uint32_t next_off;
+	struct block_reader *br;
+
+	/* key for last entry we read. */
+	struct strbuf last_key;
+};
+
+/* initializes a block reader. */
+int block_reader_init(struct block_reader *br, struct reftable_block *bl,
+		      uint32_t header_off, uint32_t table_block_size,
+		      int hash_size);
+
+/* Position `it` at start of the block */
+void block_reader_start(struct block_reader *br, struct block_iter *it);
+
+/* Position `it` to the `want` key in the block */
+int block_reader_seek(struct block_reader *br, struct block_iter *it,
+		      struct strbuf *want);
+
+/* Returns the block type (eg. 'r' for refs) */
+uint8_t block_reader_type(struct block_reader *r);
+
+/* Decodes the first key in the block */
+int block_reader_first_key(struct block_reader *br, struct strbuf *key);
+
+void block_iter_copy_from(struct block_iter *dest, struct block_iter *src);
+
+/* return < 0 for error, 0 for OK, > 0 for EOF. */
+int block_iter_next(struct block_iter *it, struct reftable_record *rec);
+
+/* Seek to `want` with in the block pointed to by `it` */
+int block_iter_seek(struct block_iter *it, struct strbuf *want);
+
+/* deallocate memory for `it`. The block reader and its block is left intact. */
+void block_iter_close(struct block_iter *it);
+
+/* size of file header, depending on format version */
+int header_size(int version);
+
+/* size of file footer, depending on format version */
+int footer_size(int version);
+
+/* returns a block to its source. */
+void reftable_block_done(struct reftable_block *ret);
+
+#endif
diff --git a/reftable/block_test.c b/reftable/block_test.c
new file mode 100644
index 0000000..4b3ea26
--- /dev/null
+++ b/reftable/block_test.c
@@ -0,0 +1,120 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "block.h"
+
+#include "system.h"
+#include "blocksource.h"
+#include "basics.h"
+#include "constants.h"
+#include "record.h"
+#include "test_framework.h"
+#include "reftable-tests.h"
+
+static void test_block_read_write(void)
+{
+	const int header_off = 21; /* random */
+	char *names[30];
+	const int N = ARRAY_SIZE(names);
+	const int block_size = 1024;
+	struct reftable_block block = { NULL };
+	struct block_writer bw = {
+		.last_key = STRBUF_INIT,
+	};
+	struct reftable_ref_record ref = { NULL };
+	struct reftable_record rec = { NULL };
+	int i = 0;
+	int n;
+	struct block_reader br = { 0 };
+	struct block_iter it = { .last_key = STRBUF_INIT };
+	int j = 0;
+	struct strbuf want = STRBUF_INIT;
+
+	block.data = reftable_calloc(block_size);
+	block.len = block_size;
+	block.source = malloc_block_source();
+	block_writer_init(&bw, BLOCK_TYPE_REF, block.data, block_size,
+			  header_off, hash_size(GIT_SHA1_FORMAT_ID));
+	reftable_record_from_ref(&rec, &ref);
+
+	for (i = 0; i < N; i++) {
+		char name[100];
+		uint8_t hash[GIT_SHA1_RAWSZ];
+		snprintf(name, sizeof(name), "branch%02d", i);
+		memset(hash, i, sizeof(hash));
+
+		ref.refname = name;
+		ref.value_type = REFTABLE_REF_VAL1;
+		ref.value.val1 = hash;
+
+		names[i] = xstrdup(name);
+		n = block_writer_add(&bw, &rec);
+		ref.refname = NULL;
+		ref.value_type = REFTABLE_REF_DELETION;
+		EXPECT(n == 0);
+	}
+
+	n = block_writer_finish(&bw);
+	EXPECT(n > 0);
+
+	block_writer_release(&bw);
+
+	block_reader_init(&br, &block, header_off, block_size, GIT_SHA1_RAWSZ);
+
+	block_reader_start(&br, &it);
+
+	while (1) {
+		int r = block_iter_next(&it, &rec);
+		EXPECT(r >= 0);
+		if (r > 0) {
+			break;
+		}
+		EXPECT_STREQ(names[j], ref.refname);
+		j++;
+	}
+
+	reftable_record_release(&rec);
+	block_iter_close(&it);
+
+	for (i = 0; i < N; i++) {
+		struct block_iter it = { .last_key = STRBUF_INIT };
+		strbuf_reset(&want);
+		strbuf_addstr(&want, names[i]);
+
+		n = block_reader_seek(&br, &it, &want);
+		EXPECT(n == 0);
+
+		n = block_iter_next(&it, &rec);
+		EXPECT(n == 0);
+
+		EXPECT_STREQ(names[i], ref.refname);
+
+		want.len--;
+		n = block_reader_seek(&br, &it, &want);
+		EXPECT(n == 0);
+
+		n = block_iter_next(&it, &rec);
+		EXPECT(n == 0);
+		EXPECT_STREQ(names[10 * (i / 10)], ref.refname);
+
+		block_iter_close(&it);
+	}
+
+	reftable_record_release(&rec);
+	reftable_block_done(&br.block);
+	strbuf_release(&want);
+	for (i = 0; i < N; i++) {
+		reftable_free(names[i]);
+	}
+}
+
+int block_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_block_read_write);
+	return 0;
+}
diff --git a/reftable/blocksource.c b/reftable/blocksource.c
new file mode 100644
index 0000000..0044eec
--- /dev/null
+++ b/reftable/blocksource.c
@@ -0,0 +1,148 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "system.h"
+
+#include "basics.h"
+#include "blocksource.h"
+#include "reftable-blocksource.h"
+#include "reftable-error.h"
+
+static void strbuf_return_block(void *b, struct reftable_block *dest)
+{
+	memset(dest->data, 0xff, dest->len);
+	reftable_free(dest->data);
+}
+
+static void strbuf_close(void *b)
+{
+}
+
+static int strbuf_read_block(void *v, struct reftable_block *dest, uint64_t off,
+			     uint32_t size)
+{
+	struct strbuf *b = v;
+	assert(off + size <= b->len);
+	dest->data = reftable_calloc(size);
+	memcpy(dest->data, b->buf + off, size);
+	dest->len = size;
+	return size;
+}
+
+static uint64_t strbuf_size(void *b)
+{
+	return ((struct strbuf *)b)->len;
+}
+
+static struct reftable_block_source_vtable strbuf_vtable = {
+	.size = &strbuf_size,
+	.read_block = &strbuf_read_block,
+	.return_block = &strbuf_return_block,
+	.close = &strbuf_close,
+};
+
+void block_source_from_strbuf(struct reftable_block_source *bs,
+			      struct strbuf *buf)
+{
+	assert(!bs->ops);
+	bs->ops = &strbuf_vtable;
+	bs->arg = buf;
+}
+
+static void malloc_return_block(void *b, struct reftable_block *dest)
+{
+	memset(dest->data, 0xff, dest->len);
+	reftable_free(dest->data);
+}
+
+static struct reftable_block_source_vtable malloc_vtable = {
+	.return_block = &malloc_return_block,
+};
+
+static struct reftable_block_source malloc_block_source_instance = {
+	.ops = &malloc_vtable,
+};
+
+struct reftable_block_source malloc_block_source(void)
+{
+	return malloc_block_source_instance;
+}
+
+struct file_block_source {
+	int fd;
+	uint64_t size;
+};
+
+static uint64_t file_size(void *b)
+{
+	return ((struct file_block_source *)b)->size;
+}
+
+static void file_return_block(void *b, struct reftable_block *dest)
+{
+	memset(dest->data, 0xff, dest->len);
+	reftable_free(dest->data);
+}
+
+static void file_close(void *b)
+{
+	int fd = ((struct file_block_source *)b)->fd;
+	if (fd > 0) {
+		close(fd);
+		((struct file_block_source *)b)->fd = 0;
+	}
+
+	reftable_free(b);
+}
+
+static int file_read_block(void *v, struct reftable_block *dest, uint64_t off,
+			   uint32_t size)
+{
+	struct file_block_source *b = v;
+	assert(off + size <= b->size);
+	dest->data = reftable_malloc(size);
+	if (pread(b->fd, dest->data, size, off) != size)
+		return -1;
+	dest->len = size;
+	return size;
+}
+
+static struct reftable_block_source_vtable file_vtable = {
+	.size = &file_size,
+	.read_block = &file_read_block,
+	.return_block = &file_return_block,
+	.close = &file_close,
+};
+
+int reftable_block_source_from_file(struct reftable_block_source *bs,
+				    const char *name)
+{
+	struct stat st = { 0 };
+	int err = 0;
+	int fd = open(name, O_RDONLY);
+	struct file_block_source *p = NULL;
+	if (fd < 0) {
+		if (errno == ENOENT) {
+			return REFTABLE_NOT_EXIST_ERROR;
+		}
+		return -1;
+	}
+
+	err = fstat(fd, &st);
+	if (err < 0)
+		return -1;
+
+	p = reftable_calloc(sizeof(struct file_block_source));
+	p->size = st.st_size;
+	p->fd = fd;
+
+	assert(!bs->ops);
+	bs->ops = &file_vtable;
+	bs->arg = p;
+	return 0;
+}
diff --git a/reftable/blocksource.h b/reftable/blocksource.h
new file mode 100644
index 0000000..072e272
--- /dev/null
+++ b/reftable/blocksource.h
@@ -0,0 +1,22 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef BLOCKSOURCE_H
+#define BLOCKSOURCE_H
+
+#include "system.h"
+
+struct reftable_block_source;
+
+/* Create an in-memory block source for reading reftables */
+void block_source_from_strbuf(struct reftable_block_source *bs,
+			      struct strbuf *buf);
+
+struct reftable_block_source malloc_block_source(void);
+
+#endif
diff --git a/reftable/constants.h b/reftable/constants.h
new file mode 100644
index 0000000..5eee72c
--- /dev/null
+++ b/reftable/constants.h
@@ -0,0 +1,21 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef CONSTANTS_H
+#define CONSTANTS_H
+
+#define BLOCK_TYPE_LOG 'g'
+#define BLOCK_TYPE_INDEX 'i'
+#define BLOCK_TYPE_REF 'r'
+#define BLOCK_TYPE_OBJ 'o'
+#define BLOCK_TYPE_ANY 0
+
+#define MAX_RESTARTS ((1 << 16) - 1)
+#define DEFAULT_BLOCK_SIZE 4096
+
+#endif
diff --git a/reftable/dump.c b/reftable/dump.c
new file mode 100644
index 0000000..155953d
--- /dev/null
+++ b/reftable/dump.c
@@ -0,0 +1,107 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "git-compat-util.h"
+#include "hash.h"
+
+#include "reftable-blocksource.h"
+#include "reftable-error.h"
+#include "reftable-merged.h"
+#include "reftable-record.h"
+#include "reftable-tests.h"
+#include "reftable-writer.h"
+#include "reftable-iterator.h"
+#include "reftable-reader.h"
+#include "reftable-stack.h"
+#include "reftable-generic.h"
+
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+static int compact_stack(const char *stackdir)
+{
+	struct reftable_stack *stack = NULL;
+	struct reftable_write_options cfg = { 0 };
+
+	int err = reftable_new_stack(&stack, stackdir, cfg);
+	if (err < 0)
+		goto done;
+
+	err = reftable_stack_compact_all(stack, NULL);
+	if (err < 0)
+		goto done;
+done:
+	if (stack) {
+		reftable_stack_destroy(stack);
+	}
+	return err;
+}
+
+static void print_help(void)
+{
+	printf("usage: dump [-cst] arg\n\n"
+	       "options: \n"
+	       "  -c compact\n"
+	       "  -t dump table\n"
+	       "  -s dump stack\n"
+	       "  -6 sha256 hash format\n"
+	       "  -h this help\n"
+	       "\n");
+}
+
+int reftable_dump_main(int argc, char *const *argv)
+{
+	int err = 0;
+	int opt_dump_table = 0;
+	int opt_dump_stack = 0;
+	int opt_compact = 0;
+	uint32_t opt_hash_id = GIT_SHA1_FORMAT_ID;
+	const char *arg = NULL, *argv0 = argv[0];
+
+	for (; argc > 1; argv++, argc--)
+		if (*argv[1] != '-')
+			break;
+		else if (!strcmp("-t", argv[1]))
+			opt_dump_table = 1;
+		else if (!strcmp("-6", argv[1]))
+			opt_hash_id = GIT_SHA256_FORMAT_ID;
+		else if (!strcmp("-s", argv[1]))
+			opt_dump_stack = 1;
+		else if (!strcmp("-c", argv[1]))
+			opt_compact = 1;
+		else if (!strcmp("-?", argv[1]) || !strcmp("-h", argv[1])) {
+			print_help();
+			return 2;
+		}
+
+	if (argc != 2) {
+		fprintf(stderr, "need argument\n");
+		print_help();
+		return 2;
+	}
+
+	arg = argv[1];
+
+	if (opt_dump_table) {
+		err = reftable_reader_print_file(arg);
+	} else if (opt_dump_stack) {
+		err = reftable_stack_print_directory(arg, opt_hash_id);
+	} else if (opt_compact) {
+		err = compact_stack(arg);
+	}
+
+	if (err < 0) {
+		fprintf(stderr, "%s: %s: %s\n", argv0, arg,
+			reftable_error_str(err));
+		return 1;
+	}
+	return 0;
+}
diff --git a/reftable/error.c b/reftable/error.c
new file mode 100644
index 0000000..93941f2
--- /dev/null
+++ b/reftable/error.c
@@ -0,0 +1,43 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "reftable-error.h"
+
+#include <stdio.h>
+
+const char *reftable_error_str(int err)
+{
+	static char buf[250];
+	switch (err) {
+	case REFTABLE_IO_ERROR:
+		return "I/O error";
+	case REFTABLE_FORMAT_ERROR:
+		return "corrupt reftable file";
+	case REFTABLE_NOT_EXIST_ERROR:
+		return "file does not exist";
+	case REFTABLE_LOCK_ERROR:
+		return "data is outdated";
+	case REFTABLE_API_ERROR:
+		return "misuse of the reftable API";
+	case REFTABLE_ZLIB_ERROR:
+		return "zlib failure";
+	case REFTABLE_NAME_CONFLICT:
+		return "file/directory conflict";
+	case REFTABLE_EMPTY_TABLE_ERROR:
+		return "wrote empty table";
+	case REFTABLE_REFNAME_ERROR:
+		return "invalid refname";
+	case REFTABLE_ENTRY_TOO_BIG_ERROR:
+		return "entry too large";
+	case -1:
+		return "general error";
+	default:
+		snprintf(buf, sizeof(buf), "unknown error code %d", err);
+		return buf;
+	}
+}
diff --git a/reftable/generic.c b/reftable/generic.c
new file mode 100644
index 0000000..7a8a738
--- /dev/null
+++ b/reftable/generic.c
@@ -0,0 +1,169 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "basics.h"
+#include "record.h"
+#include "generic.h"
+#include "reftable-iterator.h"
+#include "reftable-generic.h"
+
+int reftable_table_seek_ref(struct reftable_table *tab,
+			    struct reftable_iterator *it, const char *name)
+{
+	struct reftable_ref_record ref = {
+		.refname = (char *)name,
+	};
+	struct reftable_record rec = { NULL };
+	reftable_record_from_ref(&rec, &ref);
+	return tab->ops->seek_record(tab->table_arg, it, &rec);
+}
+
+int reftable_table_seek_log(struct reftable_table *tab,
+			    struct reftable_iterator *it, const char *name)
+{
+	struct reftable_log_record log = {
+		.refname = (char *)name,
+		.update_index = ~((uint64_t)0),
+	};
+	struct reftable_record rec = { NULL };
+	reftable_record_from_log(&rec, &log);
+	return tab->ops->seek_record(tab->table_arg, it, &rec);
+}
+
+int reftable_table_read_ref(struct reftable_table *tab, const char *name,
+			    struct reftable_ref_record *ref)
+{
+	struct reftable_iterator it = { NULL };
+	int err = reftable_table_seek_ref(tab, &it, name);
+	if (err)
+		goto done;
+
+	err = reftable_iterator_next_ref(&it, ref);
+	if (err)
+		goto done;
+
+	if (strcmp(ref->refname, name) ||
+	    reftable_ref_record_is_deletion(ref)) {
+		reftable_ref_record_release(ref);
+		err = 1;
+		goto done;
+	}
+
+done:
+	reftable_iterator_destroy(&it);
+	return err;
+}
+
+int reftable_table_print(struct reftable_table *tab) {
+	struct reftable_iterator it = { NULL };
+	struct reftable_ref_record ref = { NULL };
+	struct reftable_log_record log = { NULL };
+	uint32_t hash_id = reftable_table_hash_id(tab);
+	int err = reftable_table_seek_ref(tab, &it, "");
+	if (err < 0) {
+		return err;
+	}
+
+	while (1) {
+		err = reftable_iterator_next_ref(&it, &ref);
+		if (err > 0) {
+			break;
+		}
+		if (err < 0) {
+			return err;
+		}
+		reftable_ref_record_print(&ref, hash_id);
+	}
+	reftable_iterator_destroy(&it);
+	reftable_ref_record_release(&ref);
+
+	err = reftable_table_seek_log(tab, &it, "");
+	if (err < 0) {
+		return err;
+	}
+	while (1) {
+		err = reftable_iterator_next_log(&it, &log);
+		if (err > 0) {
+			break;
+		}
+		if (err < 0) {
+			return err;
+		}
+		reftable_log_record_print(&log, hash_id);
+	}
+	reftable_iterator_destroy(&it);
+	reftable_log_record_release(&log);
+	return 0;
+}
+
+uint64_t reftable_table_max_update_index(struct reftable_table *tab)
+{
+	return tab->ops->max_update_index(tab->table_arg);
+}
+
+uint64_t reftable_table_min_update_index(struct reftable_table *tab)
+{
+	return tab->ops->min_update_index(tab->table_arg);
+}
+
+uint32_t reftable_table_hash_id(struct reftable_table *tab)
+{
+	return tab->ops->hash_id(tab->table_arg);
+}
+
+void reftable_iterator_destroy(struct reftable_iterator *it)
+{
+	if (!it->ops) {
+		return;
+	}
+	it->ops->close(it->iter_arg);
+	it->ops = NULL;
+	FREE_AND_NULL(it->iter_arg);
+}
+
+int reftable_iterator_next_ref(struct reftable_iterator *it,
+			       struct reftable_ref_record *ref)
+{
+	struct reftable_record rec = { NULL };
+	reftable_record_from_ref(&rec, ref);
+	return iterator_next(it, &rec);
+}
+
+int reftable_iterator_next_log(struct reftable_iterator *it,
+			       struct reftable_log_record *log)
+{
+	struct reftable_record rec = { NULL };
+	reftable_record_from_log(&rec, log);
+	return iterator_next(it, &rec);
+}
+
+int iterator_next(struct reftable_iterator *it, struct reftable_record *rec)
+{
+	return it->ops->next(it->iter_arg, rec);
+}
+
+static int empty_iterator_next(void *arg, struct reftable_record *rec)
+{
+	return 1;
+}
+
+static void empty_iterator_close(void *arg)
+{
+}
+
+static struct reftable_iterator_vtable empty_vtable = {
+	.next = &empty_iterator_next,
+	.close = &empty_iterator_close,
+};
+
+void iterator_set_empty(struct reftable_iterator *it)
+{
+	assert(!it->ops);
+	it->iter_arg = NULL;
+	it->ops = &empty_vtable;
+}
diff --git a/reftable/generic.h b/reftable/generic.h
new file mode 100644
index 0000000..98886a0
--- /dev/null
+++ b/reftable/generic.h
@@ -0,0 +1,32 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef GENERIC_H
+#define GENERIC_H
+
+#include "record.h"
+#include "reftable-generic.h"
+
+/* generic interface to reftables */
+struct reftable_table_vtable {
+	int (*seek_record)(void *tab, struct reftable_iterator *it,
+			   struct reftable_record *);
+	uint32_t (*hash_id)(void *tab);
+	uint64_t (*min_update_index)(void *tab);
+	uint64_t (*max_update_index)(void *tab);
+};
+
+struct reftable_iterator_vtable {
+	int (*next)(void *iter_arg, struct reftable_record *rec);
+	void (*close)(void *iter_arg);
+};
+
+void iterator_set_empty(struct reftable_iterator *it);
+int iterator_next(struct reftable_iterator *it, struct reftable_record *rec);
+
+#endif
diff --git a/reftable/iter.c b/reftable/iter.c
new file mode 100644
index 0000000..93d04f7
--- /dev/null
+++ b/reftable/iter.c
@@ -0,0 +1,194 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "iter.h"
+
+#include "system.h"
+
+#include "block.h"
+#include "generic.h"
+#include "constants.h"
+#include "reader.h"
+#include "reftable-error.h"
+
+int iterator_is_null(struct reftable_iterator *it)
+{
+	return !it->ops;
+}
+
+static void filtering_ref_iterator_close(void *iter_arg)
+{
+	struct filtering_ref_iterator *fri = iter_arg;
+	strbuf_release(&fri->oid);
+	reftable_iterator_destroy(&fri->it);
+}
+
+static int filtering_ref_iterator_next(void *iter_arg,
+				       struct reftable_record *rec)
+{
+	struct filtering_ref_iterator *fri = iter_arg;
+	struct reftable_ref_record *ref = rec->data;
+	int err = 0;
+	while (1) {
+		err = reftable_iterator_next_ref(&fri->it, ref);
+		if (err != 0) {
+			break;
+		}
+
+		if (fri->double_check) {
+			struct reftable_iterator it = { NULL };
+
+			err = reftable_table_seek_ref(&fri->tab, &it,
+						      ref->refname);
+			if (err == 0) {
+				err = reftable_iterator_next_ref(&it, ref);
+			}
+
+			reftable_iterator_destroy(&it);
+
+			if (err < 0) {
+				break;
+			}
+
+			if (err > 0) {
+				continue;
+			}
+		}
+
+		if (ref->value_type == REFTABLE_REF_VAL2 &&
+		    (!memcmp(fri->oid.buf, ref->value.val2.target_value,
+			     fri->oid.len) ||
+		     !memcmp(fri->oid.buf, ref->value.val2.value,
+			     fri->oid.len)))
+			return 0;
+
+		if (ref->value_type == REFTABLE_REF_VAL1 &&
+		    !memcmp(fri->oid.buf, ref->value.val1, fri->oid.len)) {
+			return 0;
+		}
+	}
+
+	reftable_ref_record_release(ref);
+	return err;
+}
+
+static struct reftable_iterator_vtable filtering_ref_iterator_vtable = {
+	.next = &filtering_ref_iterator_next,
+	.close = &filtering_ref_iterator_close,
+};
+
+void iterator_from_filtering_ref_iterator(struct reftable_iterator *it,
+					  struct filtering_ref_iterator *fri)
+{
+	assert(!it->ops);
+	it->iter_arg = fri;
+	it->ops = &filtering_ref_iterator_vtable;
+}
+
+static void indexed_table_ref_iter_close(void *p)
+{
+	struct indexed_table_ref_iter *it = p;
+	block_iter_close(&it->cur);
+	reftable_block_done(&it->block_reader.block);
+	reftable_free(it->offsets);
+	strbuf_release(&it->oid);
+}
+
+static int indexed_table_ref_iter_next_block(struct indexed_table_ref_iter *it)
+{
+	uint64_t off;
+	int err = 0;
+	if (it->offset_idx == it->offset_len) {
+		it->is_finished = 1;
+		return 1;
+	}
+
+	reftable_block_done(&it->block_reader.block);
+
+	off = it->offsets[it->offset_idx++];
+	err = reader_init_block_reader(it->r, &it->block_reader, off,
+				       BLOCK_TYPE_REF);
+	if (err < 0) {
+		return err;
+	}
+	if (err > 0) {
+		/* indexed block does not exist. */
+		return REFTABLE_FORMAT_ERROR;
+	}
+	block_reader_start(&it->block_reader, &it->cur);
+	return 0;
+}
+
+static int indexed_table_ref_iter_next(void *p, struct reftable_record *rec)
+{
+	struct indexed_table_ref_iter *it = p;
+	struct reftable_ref_record *ref = rec->data;
+
+	while (1) {
+		int err = block_iter_next(&it->cur, rec);
+		if (err < 0) {
+			return err;
+		}
+
+		if (err > 0) {
+			err = indexed_table_ref_iter_next_block(it);
+			if (err < 0) {
+				return err;
+			}
+
+			if (it->is_finished) {
+				return 1;
+			}
+			continue;
+		}
+		/* BUG */
+		if (!memcmp(it->oid.buf, ref->value.val2.target_value,
+			    it->oid.len) ||
+		    !memcmp(it->oid.buf, ref->value.val2.value, it->oid.len)) {
+			return 0;
+		}
+	}
+}
+
+int new_indexed_table_ref_iter(struct indexed_table_ref_iter **dest,
+			       struct reftable_reader *r, uint8_t *oid,
+			       int oid_len, uint64_t *offsets, int offset_len)
+{
+	struct indexed_table_ref_iter empty = INDEXED_TABLE_REF_ITER_INIT;
+	struct indexed_table_ref_iter *itr =
+		reftable_calloc(sizeof(struct indexed_table_ref_iter));
+	int err = 0;
+
+	*itr = empty;
+	itr->r = r;
+	strbuf_add(&itr->oid, oid, oid_len);
+
+	itr->offsets = offsets;
+	itr->offset_len = offset_len;
+
+	err = indexed_table_ref_iter_next_block(itr);
+	if (err < 0) {
+		reftable_free(itr);
+	} else {
+		*dest = itr;
+	}
+	return err;
+}
+
+static struct reftable_iterator_vtable indexed_table_ref_iter_vtable = {
+	.next = &indexed_table_ref_iter_next,
+	.close = &indexed_table_ref_iter_close,
+};
+
+void iterator_from_indexed_table_ref_iter(struct reftable_iterator *it,
+					  struct indexed_table_ref_iter *itr)
+{
+	assert(!it->ops);
+	it->iter_arg = itr;
+	it->ops = &indexed_table_ref_iter_vtable;
+}
diff --git a/reftable/iter.h b/reftable/iter.h
new file mode 100644
index 0000000..09eb0cb
--- /dev/null
+++ b/reftable/iter.h
@@ -0,0 +1,69 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef ITER_H
+#define ITER_H
+
+#include "system.h"
+#include "block.h"
+#include "record.h"
+
+#include "reftable-iterator.h"
+#include "reftable-generic.h"
+
+/* Returns true for a zeroed out iterator, such as the one returned from
+ * iterator_destroy. */
+int iterator_is_null(struct reftable_iterator *it);
+
+/* iterator that produces only ref records that point to `oid` */
+struct filtering_ref_iterator {
+	int double_check;
+	struct reftable_table tab;
+	struct strbuf oid;
+	struct reftable_iterator it;
+};
+#define FILTERING_REF_ITERATOR_INIT \
+	{                           \
+		.oid = STRBUF_INIT  \
+	}
+
+void iterator_from_filtering_ref_iterator(struct reftable_iterator *,
+					  struct filtering_ref_iterator *);
+
+/* iterator that produces only ref records that point to `oid`,
+ * but using the object index.
+ */
+struct indexed_table_ref_iter {
+	struct reftable_reader *r;
+	struct strbuf oid;
+
+	/* mutable */
+	uint64_t *offsets;
+
+	/* Points to the next offset to read. */
+	int offset_idx;
+	int offset_len;
+	struct block_reader block_reader;
+	struct block_iter cur;
+	int is_finished;
+};
+
+#define INDEXED_TABLE_REF_ITER_INIT                                     \
+	{                                                               \
+		.cur = { .last_key = STRBUF_INIT }, .oid = STRBUF_INIT, \
+	}
+
+void iterator_from_indexed_table_ref_iter(struct reftable_iterator *it,
+					  struct indexed_table_ref_iter *itr);
+
+/* Takes ownership of `offsets` */
+int new_indexed_table_ref_iter(struct indexed_table_ref_iter **dest,
+			       struct reftable_reader *r, uint8_t *oid,
+			       int oid_len, uint64_t *offsets, int offset_len);
+
+#endif
diff --git a/reftable/merged.c b/reftable/merged.c
new file mode 100644
index 0000000..e5b53da
--- /dev/null
+++ b/reftable/merged.c
@@ -0,0 +1,362 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "merged.h"
+
+#include "constants.h"
+#include "iter.h"
+#include "pq.h"
+#include "reader.h"
+#include "record.h"
+#include "generic.h"
+#include "reftable-merged.h"
+#include "reftable-error.h"
+#include "system.h"
+
+static int merged_iter_init(struct merged_iter *mi)
+{
+	int i = 0;
+	for (i = 0; i < mi->stack_len; i++) {
+		struct reftable_record rec = reftable_new_record(mi->typ);
+		int err = iterator_next(&mi->stack[i], &rec);
+		if (err < 0) {
+			return err;
+		}
+
+		if (err > 0) {
+			reftable_iterator_destroy(&mi->stack[i]);
+			reftable_record_destroy(&rec);
+		} else {
+			struct pq_entry e = {
+				.rec = rec,
+				.index = i,
+			};
+			merged_iter_pqueue_add(&mi->pq, e);
+		}
+	}
+
+	return 0;
+}
+
+static void merged_iter_close(void *p)
+{
+	struct merged_iter *mi = p;
+	int i = 0;
+	merged_iter_pqueue_release(&mi->pq);
+	for (i = 0; i < mi->stack_len; i++) {
+		reftable_iterator_destroy(&mi->stack[i]);
+	}
+	reftable_free(mi->stack);
+}
+
+static int merged_iter_advance_nonnull_subiter(struct merged_iter *mi,
+					       size_t idx)
+{
+	struct reftable_record rec = reftable_new_record(mi->typ);
+	struct pq_entry e = {
+		.rec = rec,
+		.index = idx,
+	};
+	int err = iterator_next(&mi->stack[idx], &rec);
+	if (err < 0)
+		return err;
+
+	if (err > 0) {
+		reftable_iterator_destroy(&mi->stack[idx]);
+		reftable_record_destroy(&rec);
+		return 0;
+	}
+
+	merged_iter_pqueue_add(&mi->pq, e);
+	return 0;
+}
+
+static int merged_iter_advance_subiter(struct merged_iter *mi, size_t idx)
+{
+	if (iterator_is_null(&mi->stack[idx]))
+		return 0;
+	return merged_iter_advance_nonnull_subiter(mi, idx);
+}
+
+static int merged_iter_next_entry(struct merged_iter *mi,
+				  struct reftable_record *rec)
+{
+	struct strbuf entry_key = STRBUF_INIT;
+	struct pq_entry entry = { 0 };
+	int err = 0;
+
+	if (merged_iter_pqueue_is_empty(mi->pq))
+		return 1;
+
+	entry = merged_iter_pqueue_remove(&mi->pq);
+	err = merged_iter_advance_subiter(mi, entry.index);
+	if (err < 0)
+		return err;
+
+	/*
+	  One can also use reftable as datacenter-local storage, where the ref
+	  database is maintained in globally consistent database (eg.
+	  CockroachDB or Spanner). In this scenario, replication delays together
+	  with compaction may cause newer tables to contain older entries. In
+	  such a deployment, the loop below must be changed to collect all
+	  entries for the same key, and return new the newest one.
+	*/
+	reftable_record_key(&entry.rec, &entry_key);
+	while (!merged_iter_pqueue_is_empty(mi->pq)) {
+		struct pq_entry top = merged_iter_pqueue_top(mi->pq);
+		struct strbuf k = STRBUF_INIT;
+		int err = 0, cmp = 0;
+
+		reftable_record_key(&top.rec, &k);
+
+		cmp = strbuf_cmp(&k, &entry_key);
+		strbuf_release(&k);
+
+		if (cmp > 0) {
+			break;
+		}
+
+		merged_iter_pqueue_remove(&mi->pq);
+		err = merged_iter_advance_subiter(mi, top.index);
+		if (err < 0) {
+			return err;
+		}
+		reftable_record_destroy(&top.rec);
+	}
+
+	reftable_record_copy_from(rec, &entry.rec, hash_size(mi->hash_id));
+	reftable_record_destroy(&entry.rec);
+	strbuf_release(&entry_key);
+	return 0;
+}
+
+static int merged_iter_next(struct merged_iter *mi, struct reftable_record *rec)
+{
+	while (1) {
+		int err = merged_iter_next_entry(mi, rec);
+		if (err == 0 && mi->suppress_deletions &&
+		    reftable_record_is_deletion(rec)) {
+			continue;
+		}
+
+		return err;
+	}
+}
+
+static int merged_iter_next_void(void *p, struct reftable_record *rec)
+{
+	struct merged_iter *mi = p;
+	if (merged_iter_pqueue_is_empty(mi->pq))
+		return 1;
+
+	return merged_iter_next(mi, rec);
+}
+
+static struct reftable_iterator_vtable merged_iter_vtable = {
+	.next = &merged_iter_next_void,
+	.close = &merged_iter_close,
+};
+
+static void iterator_from_merged_iter(struct reftable_iterator *it,
+				      struct merged_iter *mi)
+{
+	assert(!it->ops);
+	it->iter_arg = mi;
+	it->ops = &merged_iter_vtable;
+}
+
+int reftable_new_merged_table(struct reftable_merged_table **dest,
+			      struct reftable_table *stack, int n,
+			      uint32_t hash_id)
+{
+	struct reftable_merged_table *m = NULL;
+	uint64_t last_max = 0;
+	uint64_t first_min = 0;
+	int i = 0;
+	for (i = 0; i < n; i++) {
+		uint64_t min = reftable_table_min_update_index(&stack[i]);
+		uint64_t max = reftable_table_max_update_index(&stack[i]);
+
+		if (reftable_table_hash_id(&stack[i]) != hash_id) {
+			return REFTABLE_FORMAT_ERROR;
+		}
+		if (i == 0 || min < first_min) {
+			first_min = min;
+		}
+		if (i == 0 || max > last_max) {
+			last_max = max;
+		}
+	}
+
+	m = reftable_calloc(sizeof(struct reftable_merged_table));
+	m->stack = stack;
+	m->stack_len = n;
+	m->min = first_min;
+	m->max = last_max;
+	m->hash_id = hash_id;
+	*dest = m;
+	return 0;
+}
+
+/* clears the list of subtable, without affecting the readers themselves. */
+void merged_table_release(struct reftable_merged_table *mt)
+{
+	FREE_AND_NULL(mt->stack);
+	mt->stack_len = 0;
+}
+
+void reftable_merged_table_free(struct reftable_merged_table *mt)
+{
+	if (!mt) {
+		return;
+	}
+	merged_table_release(mt);
+	reftable_free(mt);
+}
+
+uint64_t
+reftable_merged_table_max_update_index(struct reftable_merged_table *mt)
+{
+	return mt->max;
+}
+
+uint64_t
+reftable_merged_table_min_update_index(struct reftable_merged_table *mt)
+{
+	return mt->min;
+}
+
+static int reftable_table_seek_record(struct reftable_table *tab,
+				      struct reftable_iterator *it,
+				      struct reftable_record *rec)
+{
+	return tab->ops->seek_record(tab->table_arg, it, rec);
+}
+
+static int merged_table_seek_record(struct reftable_merged_table *mt,
+				    struct reftable_iterator *it,
+				    struct reftable_record *rec)
+{
+	struct reftable_iterator *iters = reftable_calloc(
+		sizeof(struct reftable_iterator) * mt->stack_len);
+	struct merged_iter merged = {
+		.stack = iters,
+		.typ = reftable_record_type(rec),
+		.hash_id = mt->hash_id,
+		.suppress_deletions = mt->suppress_deletions,
+	};
+	int n = 0;
+	int err = 0;
+	int i = 0;
+	for (i = 0; i < mt->stack_len && err == 0; i++) {
+		int e = reftable_table_seek_record(&mt->stack[i], &iters[n],
+						   rec);
+		if (e < 0) {
+			err = e;
+		}
+		if (e == 0) {
+			n++;
+		}
+	}
+	if (err < 0) {
+		int i = 0;
+		for (i = 0; i < n; i++) {
+			reftable_iterator_destroy(&iters[i]);
+		}
+		reftable_free(iters);
+		return err;
+	}
+
+	merged.stack_len = n;
+	err = merged_iter_init(&merged);
+	if (err < 0) {
+		merged_iter_close(&merged);
+		return err;
+	} else {
+		struct merged_iter *p =
+			reftable_malloc(sizeof(struct merged_iter));
+		*p = merged;
+		iterator_from_merged_iter(it, p);
+	}
+	return 0;
+}
+
+int reftable_merged_table_seek_ref(struct reftable_merged_table *mt,
+				   struct reftable_iterator *it,
+				   const char *name)
+{
+	struct reftable_ref_record ref = {
+		.refname = (char *)name,
+	};
+	struct reftable_record rec = { NULL };
+	reftable_record_from_ref(&rec, &ref);
+	return merged_table_seek_record(mt, it, &rec);
+}
+
+int reftable_merged_table_seek_log_at(struct reftable_merged_table *mt,
+				      struct reftable_iterator *it,
+				      const char *name, uint64_t update_index)
+{
+	struct reftable_log_record log = {
+		.refname = (char *)name,
+		.update_index = update_index,
+	};
+	struct reftable_record rec = { NULL };
+	reftable_record_from_log(&rec, &log);
+	return merged_table_seek_record(mt, it, &rec);
+}
+
+int reftable_merged_table_seek_log(struct reftable_merged_table *mt,
+				   struct reftable_iterator *it,
+				   const char *name)
+{
+	uint64_t max = ~((uint64_t)0);
+	return reftable_merged_table_seek_log_at(mt, it, name, max);
+}
+
+uint32_t reftable_merged_table_hash_id(struct reftable_merged_table *mt)
+{
+	return mt->hash_id;
+}
+
+static int reftable_merged_table_seek_void(void *tab,
+					   struct reftable_iterator *it,
+					   struct reftable_record *rec)
+{
+	return merged_table_seek_record(tab, it, rec);
+}
+
+static uint32_t reftable_merged_table_hash_id_void(void *tab)
+{
+	return reftable_merged_table_hash_id(tab);
+}
+
+static uint64_t reftable_merged_table_min_update_index_void(void *tab)
+{
+	return reftable_merged_table_min_update_index(tab);
+}
+
+static uint64_t reftable_merged_table_max_update_index_void(void *tab)
+{
+	return reftable_merged_table_max_update_index(tab);
+}
+
+static struct reftable_table_vtable merged_table_vtable = {
+	.seek_record = reftable_merged_table_seek_void,
+	.hash_id = reftable_merged_table_hash_id_void,
+	.min_update_index = reftable_merged_table_min_update_index_void,
+	.max_update_index = reftable_merged_table_max_update_index_void,
+};
+
+void reftable_table_from_merged_table(struct reftable_table *tab,
+				      struct reftable_merged_table *merged)
+{
+	assert(!tab->ops);
+	tab->ops = &merged_table_vtable;
+	tab->table_arg = merged;
+}
diff --git a/reftable/merged.h b/reftable/merged.h
new file mode 100644
index 0000000..7d9f95d
--- /dev/null
+++ b/reftable/merged.h
@@ -0,0 +1,38 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef MERGED_H
+#define MERGED_H
+
+#include "pq.h"
+
+struct reftable_merged_table {
+	struct reftable_table *stack;
+	size_t stack_len;
+	uint32_t hash_id;
+
+	/* If unset, produce deletions. This is useful for compaction. For the
+	 * full stack, deletions should be produced. */
+	int suppress_deletions;
+
+	uint64_t min;
+	uint64_t max;
+};
+
+struct merged_iter {
+	struct reftable_iterator *stack;
+	uint32_t hash_id;
+	size_t stack_len;
+	uint8_t typ;
+	int suppress_deletions;
+	struct merged_iter_pqueue pq;
+};
+
+void merged_table_release(struct reftable_merged_table *mt);
+
+#endif
diff --git a/reftable/merged_test.c b/reftable/merged_test.c
new file mode 100644
index 0000000..d08c16a
--- /dev/null
+++ b/reftable/merged_test.c
@@ -0,0 +1,468 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "merged.h"
+
+#include "system.h"
+
+#include "basics.h"
+#include "blocksource.h"
+#include "constants.h"
+#include "reader.h"
+#include "record.h"
+#include "test_framework.h"
+#include "reftable-merged.h"
+#include "reftable-tests.h"
+#include "reftable-generic.h"
+#include "reftable-writer.h"
+
+static void write_test_table(struct strbuf *buf,
+			     struct reftable_ref_record refs[], int n)
+{
+	uint64_t min = 0xffffffff;
+	uint64_t max = 0;
+	int i = 0;
+	int err;
+
+	struct reftable_write_options opts = {
+		.block_size = 256,
+	};
+	struct reftable_writer *w = NULL;
+	for (i = 0; i < n; i++) {
+		uint64_t ui = refs[i].update_index;
+		if (ui > max) {
+			max = ui;
+		}
+		if (ui < min) {
+			min = ui;
+		}
+	}
+
+	w = reftable_new_writer(&strbuf_add_void, buf, &opts);
+	reftable_writer_set_limits(w, min, max);
+
+	for (i = 0; i < n; i++) {
+		uint64_t before = refs[i].update_index;
+		int n = reftable_writer_add_ref(w, &refs[i]);
+		EXPECT(n == 0);
+		EXPECT(before == refs[i].update_index);
+	}
+
+	err = reftable_writer_close(w);
+	EXPECT_ERR(err);
+
+	reftable_writer_free(w);
+}
+
+static void write_test_log_table(struct strbuf *buf,
+				 struct reftable_log_record logs[], int n,
+				 uint64_t update_index)
+{
+	int i = 0;
+	int err;
+
+	struct reftable_write_options opts = {
+		.block_size = 256,
+		.exact_log_message = 1,
+	};
+	struct reftable_writer *w = NULL;
+	w = reftable_new_writer(&strbuf_add_void, buf, &opts);
+	reftable_writer_set_limits(w, update_index, update_index);
+
+	for (i = 0; i < n; i++) {
+		int err = reftable_writer_add_log(w, &logs[i]);
+		EXPECT_ERR(err);
+	}
+
+	err = reftable_writer_close(w);
+	EXPECT_ERR(err);
+
+	reftable_writer_free(w);
+}
+
+static struct reftable_merged_table *
+merged_table_from_records(struct reftable_ref_record **refs,
+			  struct reftable_block_source **source,
+			  struct reftable_reader ***readers, int *sizes,
+			  struct strbuf *buf, int n)
+{
+	int i = 0;
+	struct reftable_merged_table *mt = NULL;
+	int err;
+	struct reftable_table *tabs =
+		reftable_calloc(n * sizeof(struct reftable_table));
+	*readers = reftable_calloc(n * sizeof(struct reftable_reader *));
+	*source = reftable_calloc(n * sizeof(**source));
+	for (i = 0; i < n; i++) {
+		write_test_table(&buf[i], refs[i], sizes[i]);
+		block_source_from_strbuf(&(*source)[i], &buf[i]);
+
+		err = reftable_new_reader(&(*readers)[i], &(*source)[i],
+					  "name");
+		EXPECT_ERR(err);
+		reftable_table_from_reader(&tabs[i], (*readers)[i]);
+	}
+
+	err = reftable_new_merged_table(&mt, tabs, n, GIT_SHA1_FORMAT_ID);
+	EXPECT_ERR(err);
+	return mt;
+}
+
+static void readers_destroy(struct reftable_reader **readers, size_t n)
+{
+	int i = 0;
+	for (; i < n; i++)
+		reftable_reader_free(readers[i]);
+	reftable_free(readers);
+}
+
+static void test_merged_between(void)
+{
+	uint8_t hash1[GIT_SHA1_RAWSZ] = { 1, 2, 3, 0 };
+
+	struct reftable_ref_record r1[] = { {
+		.refname = "b",
+		.update_index = 1,
+		.value_type = REFTABLE_REF_VAL1,
+		.value.val1 = hash1,
+	} };
+	struct reftable_ref_record r2[] = { {
+		.refname = "a",
+		.update_index = 2,
+		.value_type = REFTABLE_REF_DELETION,
+	} };
+
+	struct reftable_ref_record *refs[] = { r1, r2 };
+	int sizes[] = { 1, 1 };
+	struct strbuf bufs[2] = { STRBUF_INIT, STRBUF_INIT };
+	struct reftable_block_source *bs = NULL;
+	struct reftable_reader **readers = NULL;
+	struct reftable_merged_table *mt =
+		merged_table_from_records(refs, &bs, &readers, sizes, bufs, 2);
+	int i;
+	struct reftable_ref_record ref = { NULL };
+	struct reftable_iterator it = { NULL };
+	int err = reftable_merged_table_seek_ref(mt, &it, "a");
+	EXPECT_ERR(err);
+
+	err = reftable_iterator_next_ref(&it, &ref);
+	EXPECT_ERR(err);
+	EXPECT(ref.update_index == 2);
+	reftable_ref_record_release(&ref);
+	reftable_iterator_destroy(&it);
+	readers_destroy(readers, 2);
+	reftable_merged_table_free(mt);
+	for (i = 0; i < ARRAY_SIZE(bufs); i++) {
+		strbuf_release(&bufs[i]);
+	}
+	reftable_free(bs);
+}
+
+static void test_merged(void)
+{
+	uint8_t hash1[GIT_SHA1_RAWSZ] = { 1 };
+	uint8_t hash2[GIT_SHA1_RAWSZ] = { 2 };
+	struct reftable_ref_record r1[] = {
+		{
+			.refname = "a",
+			.update_index = 1,
+			.value_type = REFTABLE_REF_VAL1,
+			.value.val1 = hash1,
+		},
+		{
+			.refname = "b",
+			.update_index = 1,
+			.value_type = REFTABLE_REF_VAL1,
+			.value.val1 = hash1,
+		},
+		{
+			.refname = "c",
+			.update_index = 1,
+			.value_type = REFTABLE_REF_VAL1,
+			.value.val1 = hash1,
+		}
+	};
+	struct reftable_ref_record r2[] = { {
+		.refname = "a",
+		.update_index = 2,
+		.value_type = REFTABLE_REF_DELETION,
+	} };
+	struct reftable_ref_record r3[] = {
+		{
+			.refname = "c",
+			.update_index = 3,
+			.value_type = REFTABLE_REF_VAL1,
+			.value.val1 = hash2,
+		},
+		{
+			.refname = "d",
+			.update_index = 3,
+			.value_type = REFTABLE_REF_VAL1,
+			.value.val1 = hash1,
+		},
+	};
+
+	struct reftable_ref_record *want[] = {
+		&r2[0],
+		&r1[1],
+		&r3[0],
+		&r3[1],
+	};
+
+	struct reftable_ref_record *refs[] = { r1, r2, r3 };
+	int sizes[3] = { 3, 1, 2 };
+	struct strbuf bufs[3] = { STRBUF_INIT, STRBUF_INIT, STRBUF_INIT };
+	struct reftable_block_source *bs = NULL;
+	struct reftable_reader **readers = NULL;
+	struct reftable_merged_table *mt =
+		merged_table_from_records(refs, &bs, &readers, sizes, bufs, 3);
+
+	struct reftable_iterator it = { NULL };
+	int err = reftable_merged_table_seek_ref(mt, &it, "a");
+	struct reftable_ref_record *out = NULL;
+	size_t len = 0;
+	size_t cap = 0;
+	int i = 0;
+
+	EXPECT_ERR(err);
+	EXPECT(reftable_merged_table_hash_id(mt) == GIT_SHA1_FORMAT_ID);
+	EXPECT(reftable_merged_table_min_update_index(mt) == 1);
+
+	while (len < 100) { /* cap loops/recursion. */
+		struct reftable_ref_record ref = { NULL };
+		int err = reftable_iterator_next_ref(&it, &ref);
+		if (err > 0) {
+			break;
+		}
+		if (len == cap) {
+			cap = 2 * cap + 1;
+			out = reftable_realloc(
+				out, sizeof(struct reftable_ref_record) * cap);
+		}
+		out[len++] = ref;
+	}
+	reftable_iterator_destroy(&it);
+
+	EXPECT(ARRAY_SIZE(want) == len);
+	for (i = 0; i < len; i++) {
+		EXPECT(reftable_ref_record_equal(want[i], &out[i],
+						 GIT_SHA1_RAWSZ));
+	}
+	for (i = 0; i < len; i++) {
+		reftable_ref_record_release(&out[i]);
+	}
+	reftable_free(out);
+
+	for (i = 0; i < 3; i++) {
+		strbuf_release(&bufs[i]);
+	}
+	readers_destroy(readers, 3);
+	reftable_merged_table_free(mt);
+	reftable_free(bs);
+}
+
+static struct reftable_merged_table *
+merged_table_from_log_records(struct reftable_log_record **logs,
+			      struct reftable_block_source **source,
+			      struct reftable_reader ***readers, int *sizes,
+			      struct strbuf *buf, int n)
+{
+	int i = 0;
+	struct reftable_merged_table *mt = NULL;
+	int err;
+	struct reftable_table *tabs =
+		reftable_calloc(n * sizeof(struct reftable_table));
+	*readers = reftable_calloc(n * sizeof(struct reftable_reader *));
+	*source = reftable_calloc(n * sizeof(**source));
+	for (i = 0; i < n; i++) {
+		write_test_log_table(&buf[i], logs[i], sizes[i], i + 1);
+		block_source_from_strbuf(&(*source)[i], &buf[i]);
+
+		err = reftable_new_reader(&(*readers)[i], &(*source)[i],
+					  "name");
+		EXPECT_ERR(err);
+		reftable_table_from_reader(&tabs[i], (*readers)[i]);
+	}
+
+	err = reftable_new_merged_table(&mt, tabs, n, GIT_SHA1_FORMAT_ID);
+	EXPECT_ERR(err);
+	return mt;
+}
+
+static void test_merged_logs(void)
+{
+	uint8_t hash1[GIT_SHA1_RAWSZ] = { 1 };
+	uint8_t hash2[GIT_SHA1_RAWSZ] = { 2 };
+	uint8_t hash3[GIT_SHA1_RAWSZ] = { 3 };
+	struct reftable_log_record r1[] = {
+		{
+			.refname = "a",
+			.update_index = 2,
+			.value_type = REFTABLE_LOG_UPDATE,
+			.value.update = {
+				.old_hash = hash2,
+				/* deletion */
+				.name = "jane doe",
+				.email = "jane@invalid",
+				.message = "message2",
+			}
+		},
+		{
+			.refname = "a",
+			.update_index = 1,
+			.value_type = REFTABLE_LOG_UPDATE,
+			.value.update = {
+				.old_hash = hash1,
+				.new_hash = hash2,
+				.name = "jane doe",
+				.email = "jane@invalid",
+				.message = "message1",
+			}
+		},
+	};
+	struct reftable_log_record r2[] = {
+		{
+			.refname = "a",
+			.update_index = 3,
+			.value_type = REFTABLE_LOG_UPDATE,
+			.value.update = {
+				.new_hash = hash3,
+				.name = "jane doe",
+				.email = "jane@invalid",
+				.message = "message3",
+			}
+		},
+	};
+	struct reftable_log_record r3[] = {
+		{
+			.refname = "a",
+			.update_index = 2,
+			.value_type = REFTABLE_LOG_DELETION,
+		},
+	};
+	struct reftable_log_record *want[] = {
+		&r2[0],
+		&r3[0],
+		&r1[1],
+	};
+
+	struct reftable_log_record *logs[] = { r1, r2, r3 };
+	int sizes[3] = { 2, 1, 1 };
+	struct strbuf bufs[3] = { STRBUF_INIT, STRBUF_INIT, STRBUF_INIT };
+	struct reftable_block_source *bs = NULL;
+	struct reftable_reader **readers = NULL;
+	struct reftable_merged_table *mt = merged_table_from_log_records(
+		logs, &bs, &readers, sizes, bufs, 3);
+
+	struct reftable_iterator it = { NULL };
+	int err = reftable_merged_table_seek_log(mt, &it, "a");
+	struct reftable_log_record *out = NULL;
+	size_t len = 0;
+	size_t cap = 0;
+	int i = 0;
+
+	EXPECT_ERR(err);
+	EXPECT(reftable_merged_table_hash_id(mt) == GIT_SHA1_FORMAT_ID);
+	EXPECT(reftable_merged_table_min_update_index(mt) == 1);
+
+	while (len < 100) { /* cap loops/recursion. */
+		struct reftable_log_record log = { NULL };
+		int err = reftable_iterator_next_log(&it, &log);
+		if (err > 0) {
+			break;
+		}
+		if (len == cap) {
+			cap = 2 * cap + 1;
+			out = reftable_realloc(
+				out, sizeof(struct reftable_log_record) * cap);
+		}
+		out[len++] = log;
+	}
+	reftable_iterator_destroy(&it);
+
+	EXPECT(ARRAY_SIZE(want) == len);
+	for (i = 0; i < len; i++) {
+		EXPECT(reftable_log_record_equal(want[i], &out[i],
+						 GIT_SHA1_RAWSZ));
+	}
+
+	err = reftable_merged_table_seek_log_at(mt, &it, "a", 2);
+	EXPECT_ERR(err);
+	reftable_log_record_release(&out[0]);
+	err = reftable_iterator_next_log(&it, &out[0]);
+	EXPECT_ERR(err);
+	EXPECT(reftable_log_record_equal(&out[0], &r3[0], GIT_SHA1_RAWSZ));
+	reftable_iterator_destroy(&it);
+
+	for (i = 0; i < len; i++) {
+		reftable_log_record_release(&out[i]);
+	}
+	reftable_free(out);
+
+	for (i = 0; i < 3; i++) {
+		strbuf_release(&bufs[i]);
+	}
+	readers_destroy(readers, 3);
+	reftable_merged_table_free(mt);
+	reftable_free(bs);
+}
+
+static void test_default_write_opts(void)
+{
+	struct reftable_write_options opts = { 0 };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+
+	struct reftable_ref_record rec = {
+		.refname = "master",
+		.update_index = 1,
+	};
+	int err;
+	struct reftable_block_source source = { NULL };
+	struct reftable_table *tab = reftable_calloc(sizeof(*tab) * 1);
+	uint32_t hash_id;
+	struct reftable_reader *rd = NULL;
+	struct reftable_merged_table *merged = NULL;
+
+	reftable_writer_set_limits(w, 1, 1);
+
+	err = reftable_writer_add_ref(w, &rec);
+	EXPECT_ERR(err);
+
+	err = reftable_writer_close(w);
+	EXPECT_ERR(err);
+	reftable_writer_free(w);
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = reftable_new_reader(&rd, &source, "filename");
+	EXPECT_ERR(err);
+
+	hash_id = reftable_reader_hash_id(rd);
+	EXPECT(hash_id == GIT_SHA1_FORMAT_ID);
+
+	reftable_table_from_reader(&tab[0], rd);
+	err = reftable_new_merged_table(&merged, tab, 1, GIT_SHA1_FORMAT_ID);
+	EXPECT_ERR(err);
+
+	reftable_reader_free(rd);
+	reftable_merged_table_free(merged);
+	strbuf_release(&buf);
+}
+
+/* XXX test refs_for(oid) */
+
+int merged_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_merged_logs);
+	RUN_TEST(test_merged_between);
+	RUN_TEST(test_merged);
+	RUN_TEST(test_default_write_opts);
+	return 0;
+}
diff --git a/reftable/pq.c b/reftable/pq.c
new file mode 100644
index 0000000..efc4740
--- /dev/null
+++ b/reftable/pq.c
@@ -0,0 +1,105 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "pq.h"
+
+#include "reftable-record.h"
+#include "system.h"
+#include "basics.h"
+
+int pq_less(struct pq_entry *a, struct pq_entry *b)
+{
+	struct strbuf ak = STRBUF_INIT;
+	struct strbuf bk = STRBUF_INIT;
+	int cmp = 0;
+	reftable_record_key(&a->rec, &ak);
+	reftable_record_key(&b->rec, &bk);
+
+	cmp = strbuf_cmp(&ak, &bk);
+
+	strbuf_release(&ak);
+	strbuf_release(&bk);
+
+	if (cmp == 0)
+		return a->index > b->index;
+
+	return cmp < 0;
+}
+
+struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq)
+{
+	return pq.heap[0];
+}
+
+int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq)
+{
+	return pq.len == 0;
+}
+
+struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq)
+{
+	int i = 0;
+	struct pq_entry e = pq->heap[0];
+	pq->heap[0] = pq->heap[pq->len - 1];
+	pq->len--;
+
+	i = 0;
+	while (i < pq->len) {
+		int min = i;
+		int j = 2 * i + 1;
+		int k = 2 * i + 2;
+		if (j < pq->len && pq_less(&pq->heap[j], &pq->heap[i])) {
+			min = j;
+		}
+		if (k < pq->len && pq_less(&pq->heap[k], &pq->heap[min])) {
+			min = k;
+		}
+
+		if (min == i) {
+			break;
+		}
+
+		SWAP(pq->heap[i], pq->heap[min]);
+		i = min;
+	}
+
+	return e;
+}
+
+void merged_iter_pqueue_add(struct merged_iter_pqueue *pq, struct pq_entry e)
+{
+	int i = 0;
+	if (pq->len == pq->cap) {
+		pq->cap = 2 * pq->cap + 1;
+		pq->heap = reftable_realloc(pq->heap,
+					    pq->cap * sizeof(struct pq_entry));
+	}
+
+	pq->heap[pq->len++] = e;
+	i = pq->len - 1;
+	while (i > 0) {
+		int j = (i - 1) / 2;
+		if (pq_less(&pq->heap[j], &pq->heap[i])) {
+			break;
+		}
+
+		SWAP(pq->heap[j], pq->heap[i]);
+
+		i = j;
+	}
+}
+
+void merged_iter_pqueue_release(struct merged_iter_pqueue *pq)
+{
+	int i = 0;
+	for (i = 0; i < pq->len; i++) {
+		reftable_record_destroy(&pq->heap[i].rec);
+	}
+	FREE_AND_NULL(pq->heap);
+	pq->len = pq->cap = 0;
+}
diff --git a/reftable/pq.h b/reftable/pq.h
new file mode 100644
index 0000000..56fc1b6
--- /dev/null
+++ b/reftable/pq.h
@@ -0,0 +1,33 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef PQ_H
+#define PQ_H
+
+#include "record.h"
+
+struct pq_entry {
+	int index;
+	struct reftable_record rec;
+};
+
+struct merged_iter_pqueue {
+	struct pq_entry *heap;
+	size_t len;
+	size_t cap;
+};
+
+struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq);
+int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq);
+void merged_iter_pqueue_check(struct merged_iter_pqueue pq);
+struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq);
+void merged_iter_pqueue_add(struct merged_iter_pqueue *pq, struct pq_entry e);
+void merged_iter_pqueue_release(struct merged_iter_pqueue *pq);
+int pq_less(struct pq_entry *a, struct pq_entry *b);
+
+#endif
diff --git a/reftable/pq_test.c b/reftable/pq_test.c
new file mode 100644
index 0000000..c9bb05e
--- /dev/null
+++ b/reftable/pq_test.c
@@ -0,0 +1,82 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "system.h"
+
+#include "basics.h"
+#include "constants.h"
+#include "pq.h"
+#include "record.h"
+#include "reftable-tests.h"
+#include "test_framework.h"
+
+void merged_iter_pqueue_check(struct merged_iter_pqueue pq)
+{
+	int i;
+	for (i = 1; i < pq.len; i++) {
+		int parent = (i - 1) / 2;
+
+		EXPECT(pq_less(&pq.heap[parent], &pq.heap[i]));
+	}
+}
+
+static void test_pq(void)
+{
+	char *names[54] = { NULL };
+	int N = ARRAY_SIZE(names) - 1;
+
+	struct merged_iter_pqueue pq = { NULL };
+	const char *last = NULL;
+
+	int i = 0;
+	for (i = 0; i < N; i++) {
+		char name[100];
+		snprintf(name, sizeof(name), "%02d", i);
+		names[i] = xstrdup(name);
+	}
+
+	i = 1;
+	do {
+		struct reftable_record rec =
+			reftable_new_record(BLOCK_TYPE_REF);
+		struct pq_entry e = { 0 };
+
+		reftable_record_as_ref(&rec)->refname = names[i];
+		e.rec = rec;
+		merged_iter_pqueue_add(&pq, e);
+		merged_iter_pqueue_check(pq);
+		i = (i * 7) % N;
+	} while (i != 1);
+
+	while (!merged_iter_pqueue_is_empty(pq)) {
+		struct pq_entry e = merged_iter_pqueue_remove(&pq);
+		struct reftable_ref_record *ref =
+			reftable_record_as_ref(&e.rec);
+
+		merged_iter_pqueue_check(pq);
+
+		if (last) {
+			EXPECT(strcmp(last, ref->refname) < 0);
+		}
+		last = ref->refname;
+		ref->refname = NULL;
+		reftable_free(ref);
+	}
+
+	for (i = 0; i < N; i++) {
+		reftable_free(names[i]);
+	}
+
+	merged_iter_pqueue_release(&pq);
+}
+
+int pq_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_pq);
+	return 0;
+}
diff --git a/reftable/publicbasics.c b/reftable/publicbasics.c
new file mode 100644
index 0000000..0ad7d5c
--- /dev/null
+++ b/reftable/publicbasics.c
@@ -0,0 +1,65 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "reftable-malloc.h"
+
+#include "basics.h"
+#include "system.h"
+
+static void *(*reftable_malloc_ptr)(size_t sz);
+static void *(*reftable_realloc_ptr)(void *, size_t);
+static void (*reftable_free_ptr)(void *);
+
+void *reftable_malloc(size_t sz)
+{
+	if (reftable_malloc_ptr)
+		return (*reftable_malloc_ptr)(sz);
+	return malloc(sz);
+}
+
+void *reftable_realloc(void *p, size_t sz)
+{
+	if (reftable_realloc_ptr)
+		return (*reftable_realloc_ptr)(p, sz);
+	return realloc(p, sz);
+}
+
+void reftable_free(void *p)
+{
+	if (reftable_free_ptr)
+		reftable_free_ptr(p);
+	else
+		free(p);
+}
+
+void *reftable_calloc(size_t sz)
+{
+	void *p = reftable_malloc(sz);
+	memset(p, 0, sz);
+	return p;
+}
+
+void reftable_set_alloc(void *(*malloc)(size_t),
+			void *(*realloc)(void *, size_t), void (*free)(void *))
+{
+	reftable_malloc_ptr = malloc;
+	reftable_realloc_ptr = realloc;
+	reftable_free_ptr = free;
+}
+
+int hash_size(uint32_t id)
+{
+	switch (id) {
+	case 0:
+	case GIT_SHA1_FORMAT_ID:
+		return GIT_SHA1_RAWSZ;
+	case GIT_SHA256_FORMAT_ID:
+		return GIT_SHA256_RAWSZ;
+	}
+	abort();
+}
diff --git a/reftable/reader.c b/reftable/reader.c
new file mode 100644
index 0000000..006709a
--- /dev/null
+++ b/reftable/reader.c
@@ -0,0 +1,801 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "reader.h"
+
+#include "system.h"
+#include "block.h"
+#include "constants.h"
+#include "generic.h"
+#include "iter.h"
+#include "record.h"
+#include "reftable-error.h"
+#include "reftable-generic.h"
+#include "tree.h"
+
+uint64_t block_source_size(struct reftable_block_source *source)
+{
+	return source->ops->size(source->arg);
+}
+
+int block_source_read_block(struct reftable_block_source *source,
+			    struct reftable_block *dest, uint64_t off,
+			    uint32_t size)
+{
+	int result = source->ops->read_block(source->arg, dest, off, size);
+	dest->source = *source;
+	return result;
+}
+
+void block_source_close(struct reftable_block_source *source)
+{
+	if (!source->ops) {
+		return;
+	}
+
+	source->ops->close(source->arg);
+	source->ops = NULL;
+}
+
+static struct reftable_reader_offsets *
+reader_offsets_for(struct reftable_reader *r, uint8_t typ)
+{
+	switch (typ) {
+	case BLOCK_TYPE_REF:
+		return &r->ref_offsets;
+	case BLOCK_TYPE_LOG:
+		return &r->log_offsets;
+	case BLOCK_TYPE_OBJ:
+		return &r->obj_offsets;
+	}
+	abort();
+}
+
+static int reader_get_block(struct reftable_reader *r,
+			    struct reftable_block *dest, uint64_t off,
+			    uint32_t sz)
+{
+	if (off >= r->size)
+		return 0;
+
+	if (off + sz > r->size) {
+		sz = r->size - off;
+	}
+
+	return block_source_read_block(&r->source, dest, off, sz);
+}
+
+uint32_t reftable_reader_hash_id(struct reftable_reader *r)
+{
+	return r->hash_id;
+}
+
+const char *reader_name(struct reftable_reader *r)
+{
+	return r->name;
+}
+
+static int parse_footer(struct reftable_reader *r, uint8_t *footer,
+			uint8_t *header)
+{
+	uint8_t *f = footer;
+	uint8_t first_block_typ;
+	int err = 0;
+	uint32_t computed_crc;
+	uint32_t file_crc;
+
+	if (memcmp(f, "REFT", 4)) {
+		err = REFTABLE_FORMAT_ERROR;
+		goto done;
+	}
+	f += 4;
+
+	if (memcmp(footer, header, header_size(r->version))) {
+		err = REFTABLE_FORMAT_ERROR;
+		goto done;
+	}
+
+	f++;
+	r->block_size = get_be24(f);
+
+	f += 3;
+	r->min_update_index = get_be64(f);
+	f += 8;
+	r->max_update_index = get_be64(f);
+	f += 8;
+
+	if (r->version == 1) {
+		r->hash_id = GIT_SHA1_FORMAT_ID;
+	} else {
+		r->hash_id = get_be32(f);
+		switch (r->hash_id) {
+		case GIT_SHA1_FORMAT_ID:
+			break;
+		case GIT_SHA256_FORMAT_ID:
+			break;
+		default:
+			err = REFTABLE_FORMAT_ERROR;
+			goto done;
+		}
+		f += 4;
+	}
+
+	r->ref_offsets.index_offset = get_be64(f);
+	f += 8;
+
+	r->obj_offsets.offset = get_be64(f);
+	f += 8;
+
+	r->object_id_len = r->obj_offsets.offset & ((1 << 5) - 1);
+	r->obj_offsets.offset >>= 5;
+
+	r->obj_offsets.index_offset = get_be64(f);
+	f += 8;
+	r->log_offsets.offset = get_be64(f);
+	f += 8;
+	r->log_offsets.index_offset = get_be64(f);
+	f += 8;
+
+	computed_crc = crc32(0, footer, f - footer);
+	file_crc = get_be32(f);
+	f += 4;
+	if (computed_crc != file_crc) {
+		err = REFTABLE_FORMAT_ERROR;
+		goto done;
+	}
+
+	first_block_typ = header[header_size(r->version)];
+	r->ref_offsets.is_present = (first_block_typ == BLOCK_TYPE_REF);
+	r->ref_offsets.offset = 0;
+	r->log_offsets.is_present = (first_block_typ == BLOCK_TYPE_LOG ||
+				     r->log_offsets.offset > 0);
+	r->obj_offsets.is_present = r->obj_offsets.offset > 0;
+	err = 0;
+done:
+	return err;
+}
+
+int init_reader(struct reftable_reader *r, struct reftable_block_source *source,
+		const char *name)
+{
+	struct reftable_block footer = { NULL };
+	struct reftable_block header = { NULL };
+	int err = 0;
+	uint64_t file_size = block_source_size(source);
+
+	/* Need +1 to read type of first block. */
+	uint32_t read_size = header_size(2) + 1; /* read v2 because it's larger.  */
+	memset(r, 0, sizeof(struct reftable_reader));
+
+	if (read_size > file_size) {
+		err = REFTABLE_FORMAT_ERROR;
+		goto done;
+	}
+
+	err = block_source_read_block(source, &header, 0, read_size);
+	if (err != read_size) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+
+	if (memcmp(header.data, "REFT", 4)) {
+		err = REFTABLE_FORMAT_ERROR;
+		goto done;
+	}
+	r->version = header.data[4];
+	if (r->version != 1 && r->version != 2) {
+		err = REFTABLE_FORMAT_ERROR;
+		goto done;
+	}
+
+	r->size = file_size - footer_size(r->version);
+	r->source = *source;
+	r->name = xstrdup(name);
+	r->hash_id = 0;
+
+	err = block_source_read_block(source, &footer, r->size,
+				      footer_size(r->version));
+	if (err != footer_size(r->version)) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+
+	err = parse_footer(r, footer.data, header.data);
+done:
+	reftable_block_done(&footer);
+	reftable_block_done(&header);
+	return err;
+}
+
+struct table_iter {
+	struct reftable_reader *r;
+	uint8_t typ;
+	uint64_t block_off;
+	struct block_iter bi;
+	int is_finished;
+};
+#define TABLE_ITER_INIT                          \
+	{                                        \
+		.bi = {.last_key = STRBUF_INIT } \
+	}
+
+static void table_iter_copy_from(struct table_iter *dest,
+				 struct table_iter *src)
+{
+	dest->r = src->r;
+	dest->typ = src->typ;
+	dest->block_off = src->block_off;
+	dest->is_finished = src->is_finished;
+	block_iter_copy_from(&dest->bi, &src->bi);
+}
+
+static int table_iter_next_in_block(struct table_iter *ti,
+				    struct reftable_record *rec)
+{
+	int res = block_iter_next(&ti->bi, rec);
+	if (res == 0 && reftable_record_type(rec) == BLOCK_TYPE_REF) {
+		((struct reftable_ref_record *)rec->data)->update_index +=
+			ti->r->min_update_index;
+	}
+
+	return res;
+}
+
+static void table_iter_block_done(struct table_iter *ti)
+{
+	if (!ti->bi.br) {
+		return;
+	}
+	reftable_block_done(&ti->bi.br->block);
+	FREE_AND_NULL(ti->bi.br);
+
+	ti->bi.last_key.len = 0;
+	ti->bi.next_off = 0;
+}
+
+static int32_t extract_block_size(uint8_t *data, uint8_t *typ, uint64_t off,
+				  int version)
+{
+	int32_t result = 0;
+
+	if (off == 0) {
+		data += header_size(version);
+	}
+
+	*typ = data[0];
+	if (reftable_is_block_type(*typ)) {
+		result = get_be24(data + 1);
+	}
+	return result;
+}
+
+int reader_init_block_reader(struct reftable_reader *r, struct block_reader *br,
+			     uint64_t next_off, uint8_t want_typ)
+{
+	int32_t guess_block_size = r->block_size ? r->block_size :
+							 DEFAULT_BLOCK_SIZE;
+	struct reftable_block block = { NULL };
+	uint8_t block_typ = 0;
+	int err = 0;
+	uint32_t header_off = next_off ? 0 : header_size(r->version);
+	int32_t block_size = 0;
+
+	if (next_off >= r->size)
+		return 1;
+
+	err = reader_get_block(r, &block, next_off, guess_block_size);
+	if (err < 0)
+		return err;
+
+	block_size = extract_block_size(block.data, &block_typ, next_off,
+					r->version);
+	if (block_size < 0)
+		return block_size;
+
+	if (want_typ != BLOCK_TYPE_ANY && block_typ != want_typ) {
+		reftable_block_done(&block);
+		return 1;
+	}
+
+	if (block_size > guess_block_size) {
+		reftable_block_done(&block);
+		err = reader_get_block(r, &block, next_off, block_size);
+		if (err < 0) {
+			return err;
+		}
+	}
+
+	return block_reader_init(br, &block, header_off, r->block_size,
+				 hash_size(r->hash_id));
+}
+
+static int table_iter_next_block(struct table_iter *dest,
+				 struct table_iter *src)
+{
+	uint64_t next_block_off = src->block_off + src->bi.br->full_block_size;
+	struct block_reader br = { 0 };
+	int err = 0;
+
+	dest->r = src->r;
+	dest->typ = src->typ;
+	dest->block_off = next_block_off;
+
+	err = reader_init_block_reader(src->r, &br, next_block_off, src->typ);
+	if (err > 0) {
+		dest->is_finished = 1;
+		return 1;
+	}
+	if (err != 0)
+		return err;
+	else {
+		struct block_reader *brp =
+			reftable_malloc(sizeof(struct block_reader));
+		*brp = br;
+
+		dest->is_finished = 0;
+		block_reader_start(brp, &dest->bi);
+	}
+	return 0;
+}
+
+static int table_iter_next(struct table_iter *ti, struct reftable_record *rec)
+{
+	if (reftable_record_type(rec) != ti->typ)
+		return REFTABLE_API_ERROR;
+
+	while (1) {
+		struct table_iter next = TABLE_ITER_INIT;
+		int err = 0;
+		if (ti->is_finished) {
+			return 1;
+		}
+
+		err = table_iter_next_in_block(ti, rec);
+		if (err <= 0) {
+			return err;
+		}
+
+		err = table_iter_next_block(&next, ti);
+		if (err != 0) {
+			ti->is_finished = 1;
+		}
+		table_iter_block_done(ti);
+		if (err != 0) {
+			return err;
+		}
+		table_iter_copy_from(ti, &next);
+		block_iter_close(&next.bi);
+	}
+}
+
+static int table_iter_next_void(void *ti, struct reftable_record *rec)
+{
+	return table_iter_next(ti, rec);
+}
+
+static void table_iter_close(void *p)
+{
+	struct table_iter *ti = p;
+	table_iter_block_done(ti);
+	block_iter_close(&ti->bi);
+}
+
+static struct reftable_iterator_vtable table_iter_vtable = {
+	.next = &table_iter_next_void,
+	.close = &table_iter_close,
+};
+
+static void iterator_from_table_iter(struct reftable_iterator *it,
+				     struct table_iter *ti)
+{
+	assert(!it->ops);
+	it->iter_arg = ti;
+	it->ops = &table_iter_vtable;
+}
+
+static int reader_table_iter_at(struct reftable_reader *r,
+				struct table_iter *ti, uint64_t off,
+				uint8_t typ)
+{
+	struct block_reader br = { 0 };
+	struct block_reader *brp = NULL;
+
+	int err = reader_init_block_reader(r, &br, off, typ);
+	if (err != 0)
+		return err;
+
+	brp = reftable_malloc(sizeof(struct block_reader));
+	*brp = br;
+	ti->r = r;
+	ti->typ = block_reader_type(brp);
+	ti->block_off = off;
+	block_reader_start(brp, &ti->bi);
+	return 0;
+}
+
+static int reader_start(struct reftable_reader *r, struct table_iter *ti,
+			uint8_t typ, int index)
+{
+	struct reftable_reader_offsets *offs = reader_offsets_for(r, typ);
+	uint64_t off = offs->offset;
+	if (index) {
+		off = offs->index_offset;
+		if (off == 0) {
+			return 1;
+		}
+		typ = BLOCK_TYPE_INDEX;
+	}
+
+	return reader_table_iter_at(r, ti, off, typ);
+}
+
+static int reader_seek_linear(struct reftable_reader *r, struct table_iter *ti,
+			      struct reftable_record *want)
+{
+	struct reftable_record rec =
+		reftable_new_record(reftable_record_type(want));
+	struct strbuf want_key = STRBUF_INIT;
+	struct strbuf got_key = STRBUF_INIT;
+	struct table_iter next = TABLE_ITER_INIT;
+	int err = -1;
+
+	reftable_record_key(want, &want_key);
+
+	while (1) {
+		err = table_iter_next_block(&next, ti);
+		if (err < 0)
+			goto done;
+
+		if (err > 0) {
+			break;
+		}
+
+		err = block_reader_first_key(next.bi.br, &got_key);
+		if (err < 0)
+			goto done;
+
+		if (strbuf_cmp(&got_key, &want_key) > 0) {
+			table_iter_block_done(&next);
+			break;
+		}
+
+		table_iter_block_done(ti);
+		table_iter_copy_from(ti, &next);
+	}
+
+	err = block_iter_seek(&ti->bi, &want_key);
+	if (err < 0)
+		goto done;
+	err = 0;
+
+done:
+	block_iter_close(&next.bi);
+	reftable_record_destroy(&rec);
+	strbuf_release(&want_key);
+	strbuf_release(&got_key);
+	return err;
+}
+
+static int reader_seek_indexed(struct reftable_reader *r,
+			       struct reftable_iterator *it,
+			       struct reftable_record *rec)
+{
+	struct reftable_index_record want_index = { .last_key = STRBUF_INIT };
+	struct reftable_record want_index_rec = { NULL };
+	struct reftable_index_record index_result = { .last_key = STRBUF_INIT };
+	struct reftable_record index_result_rec = { NULL };
+	struct table_iter index_iter = TABLE_ITER_INIT;
+	struct table_iter next = TABLE_ITER_INIT;
+	int err = 0;
+
+	reftable_record_key(rec, &want_index.last_key);
+	reftable_record_from_index(&want_index_rec, &want_index);
+	reftable_record_from_index(&index_result_rec, &index_result);
+
+	err = reader_start(r, &index_iter, reftable_record_type(rec), 1);
+	if (err < 0)
+		goto done;
+
+	err = reader_seek_linear(r, &index_iter, &want_index_rec);
+	while (1) {
+		err = table_iter_next(&index_iter, &index_result_rec);
+		table_iter_block_done(&index_iter);
+		if (err != 0)
+			goto done;
+
+		err = reader_table_iter_at(r, &next, index_result.offset, 0);
+		if (err != 0)
+			goto done;
+
+		err = block_iter_seek(&next.bi, &want_index.last_key);
+		if (err < 0)
+			goto done;
+
+		if (next.typ == reftable_record_type(rec)) {
+			err = 0;
+			break;
+		}
+
+		if (next.typ != BLOCK_TYPE_INDEX) {
+			err = REFTABLE_FORMAT_ERROR;
+			break;
+		}
+
+		table_iter_copy_from(&index_iter, &next);
+	}
+
+	if (err == 0) {
+		struct table_iter empty = TABLE_ITER_INIT;
+		struct table_iter *malloced =
+			reftable_calloc(sizeof(struct table_iter));
+		*malloced = empty;
+		table_iter_copy_from(malloced, &next);
+		iterator_from_table_iter(it, malloced);
+	}
+done:
+	block_iter_close(&next.bi);
+	table_iter_close(&index_iter);
+	reftable_record_release(&want_index_rec);
+	reftable_record_release(&index_result_rec);
+	return err;
+}
+
+static int reader_seek_internal(struct reftable_reader *r,
+				struct reftable_iterator *it,
+				struct reftable_record *rec)
+{
+	struct reftable_reader_offsets *offs =
+		reader_offsets_for(r, reftable_record_type(rec));
+	uint64_t idx = offs->index_offset;
+	struct table_iter ti = TABLE_ITER_INIT;
+	int err = 0;
+	if (idx > 0)
+		return reader_seek_indexed(r, it, rec);
+
+	err = reader_start(r, &ti, reftable_record_type(rec), 0);
+	if (err < 0)
+		return err;
+	err = reader_seek_linear(r, &ti, rec);
+	if (err < 0)
+		return err;
+	else {
+		struct table_iter *p =
+			reftable_malloc(sizeof(struct table_iter));
+		*p = ti;
+		iterator_from_table_iter(it, p);
+	}
+
+	return 0;
+}
+
+static int reader_seek(struct reftable_reader *r, struct reftable_iterator *it,
+		       struct reftable_record *rec)
+{
+	uint8_t typ = reftable_record_type(rec);
+
+	struct reftable_reader_offsets *offs = reader_offsets_for(r, typ);
+	if (!offs->is_present) {
+		iterator_set_empty(it);
+		return 0;
+	}
+
+	return reader_seek_internal(r, it, rec);
+}
+
+int reftable_reader_seek_ref(struct reftable_reader *r,
+			     struct reftable_iterator *it, const char *name)
+{
+	struct reftable_ref_record ref = {
+		.refname = (char *)name,
+	};
+	struct reftable_record rec = { NULL };
+	reftable_record_from_ref(&rec, &ref);
+	return reader_seek(r, it, &rec);
+}
+
+int reftable_reader_seek_log_at(struct reftable_reader *r,
+				struct reftable_iterator *it, const char *name,
+				uint64_t update_index)
+{
+	struct reftable_log_record log = {
+		.refname = (char *)name,
+		.update_index = update_index,
+	};
+	struct reftable_record rec = { NULL };
+	reftable_record_from_log(&rec, &log);
+	return reader_seek(r, it, &rec);
+}
+
+int reftable_reader_seek_log(struct reftable_reader *r,
+			     struct reftable_iterator *it, const char *name)
+{
+	uint64_t max = ~((uint64_t)0);
+	return reftable_reader_seek_log_at(r, it, name, max);
+}
+
+void reader_close(struct reftable_reader *r)
+{
+	block_source_close(&r->source);
+	FREE_AND_NULL(r->name);
+}
+
+int reftable_new_reader(struct reftable_reader **p,
+			struct reftable_block_source *src, char const *name)
+{
+	struct reftable_reader *rd =
+		reftable_calloc(sizeof(struct reftable_reader));
+	int err = init_reader(rd, src, name);
+	if (err == 0) {
+		*p = rd;
+	} else {
+		block_source_close(src);
+		reftable_free(rd);
+	}
+	return err;
+}
+
+void reftable_reader_free(struct reftable_reader *r)
+{
+	reader_close(r);
+	reftable_free(r);
+}
+
+static int reftable_reader_refs_for_indexed(struct reftable_reader *r,
+					    struct reftable_iterator *it,
+					    uint8_t *oid)
+{
+	struct reftable_obj_record want = {
+		.hash_prefix = oid,
+		.hash_prefix_len = r->object_id_len,
+	};
+	struct reftable_record want_rec = { NULL };
+	struct reftable_iterator oit = { NULL };
+	struct reftable_obj_record got = { NULL };
+	struct reftable_record got_rec = { NULL };
+	int err = 0;
+	struct indexed_table_ref_iter *itr = NULL;
+
+	/* Look through the reverse index. */
+	reftable_record_from_obj(&want_rec, &want);
+	err = reader_seek(r, &oit, &want_rec);
+	if (err != 0)
+		goto done;
+
+	/* read out the reftable_obj_record */
+	reftable_record_from_obj(&got_rec, &got);
+	err = iterator_next(&oit, &got_rec);
+	if (err < 0)
+		goto done;
+
+	if (err > 0 ||
+	    memcmp(want.hash_prefix, got.hash_prefix, r->object_id_len)) {
+		/* didn't find it; return empty iterator */
+		iterator_set_empty(it);
+		err = 0;
+		goto done;
+	}
+
+	err = new_indexed_table_ref_iter(&itr, r, oid, hash_size(r->hash_id),
+					 got.offsets, got.offset_len);
+	if (err < 0)
+		goto done;
+	got.offsets = NULL;
+	iterator_from_indexed_table_ref_iter(it, itr);
+
+done:
+	reftable_iterator_destroy(&oit);
+	reftable_record_release(&got_rec);
+	return err;
+}
+
+static int reftable_reader_refs_for_unindexed(struct reftable_reader *r,
+					      struct reftable_iterator *it,
+					      uint8_t *oid)
+{
+	struct table_iter ti_empty = TABLE_ITER_INIT;
+	struct table_iter *ti = reftable_calloc(sizeof(struct table_iter));
+	struct filtering_ref_iterator *filter = NULL;
+	struct filtering_ref_iterator empty = FILTERING_REF_ITERATOR_INIT;
+	int oid_len = hash_size(r->hash_id);
+	int err;
+
+	*ti = ti_empty;
+	err = reader_start(r, ti, BLOCK_TYPE_REF, 0);
+	if (err < 0) {
+		reftable_free(ti);
+		return err;
+	}
+
+	filter = reftable_malloc(sizeof(struct filtering_ref_iterator));
+	*filter = empty;
+
+	strbuf_add(&filter->oid, oid, oid_len);
+	reftable_table_from_reader(&filter->tab, r);
+	filter->double_check = 0;
+	iterator_from_table_iter(&filter->it, ti);
+
+	iterator_from_filtering_ref_iterator(it, filter);
+	return 0;
+}
+
+int reftable_reader_refs_for(struct reftable_reader *r,
+			     struct reftable_iterator *it, uint8_t *oid)
+{
+	if (r->obj_offsets.is_present)
+		return reftable_reader_refs_for_indexed(r, it, oid);
+	return reftable_reader_refs_for_unindexed(r, it, oid);
+}
+
+uint64_t reftable_reader_max_update_index(struct reftable_reader *r)
+{
+	return r->max_update_index;
+}
+
+uint64_t reftable_reader_min_update_index(struct reftable_reader *r)
+{
+	return r->min_update_index;
+}
+
+/* generic table interface. */
+
+static int reftable_reader_seek_void(void *tab, struct reftable_iterator *it,
+				     struct reftable_record *rec)
+{
+	return reader_seek(tab, it, rec);
+}
+
+static uint32_t reftable_reader_hash_id_void(void *tab)
+{
+	return reftable_reader_hash_id(tab);
+}
+
+static uint64_t reftable_reader_min_update_index_void(void *tab)
+{
+	return reftable_reader_min_update_index(tab);
+}
+
+static uint64_t reftable_reader_max_update_index_void(void *tab)
+{
+	return reftable_reader_max_update_index(tab);
+}
+
+static struct reftable_table_vtable reader_vtable = {
+	.seek_record = reftable_reader_seek_void,
+	.hash_id = reftable_reader_hash_id_void,
+	.min_update_index = reftable_reader_min_update_index_void,
+	.max_update_index = reftable_reader_max_update_index_void,
+};
+
+void reftable_table_from_reader(struct reftable_table *tab,
+				struct reftable_reader *reader)
+{
+	assert(!tab->ops);
+	tab->ops = &reader_vtable;
+	tab->table_arg = reader;
+}
+
+
+int reftable_reader_print_file(const char *tablename)
+{
+	struct reftable_block_source src = { NULL };
+	int err = reftable_block_source_from_file(&src, tablename);
+	struct reftable_reader *r = NULL;
+	struct reftable_table tab = { NULL };
+	if (err < 0)
+		goto done;
+
+	err = reftable_new_reader(&r, &src, tablename);
+	if (err < 0)
+		goto done;
+
+	reftable_table_from_reader(&tab, r);
+	err = reftable_table_print(&tab);
+done:
+	reftable_reader_free(r);
+	return err;
+}
diff --git a/reftable/reader.h b/reftable/reader.h
new file mode 100644
index 0000000..e869165
--- /dev/null
+++ b/reftable/reader.h
@@ -0,0 +1,64 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef READER_H
+#define READER_H
+
+#include "block.h"
+#include "record.h"
+#include "reftable-iterator.h"
+#include "reftable-reader.h"
+
+uint64_t block_source_size(struct reftable_block_source *source);
+
+int block_source_read_block(struct reftable_block_source *source,
+			    struct reftable_block *dest, uint64_t off,
+			    uint32_t size);
+void block_source_close(struct reftable_block_source *source);
+
+/* metadata for a block type */
+struct reftable_reader_offsets {
+	int is_present;
+	uint64_t offset;
+	uint64_t index_offset;
+};
+
+/* The state for reading a reftable file. */
+struct reftable_reader {
+	/* for convience, associate a name with the instance. */
+	char *name;
+	struct reftable_block_source source;
+
+	/* Size of the file, excluding the footer. */
+	uint64_t size;
+
+	/* 'sha1' for SHA1, 's256' for SHA-256 */
+	uint32_t hash_id;
+
+	uint32_t block_size;
+	uint64_t min_update_index;
+	uint64_t max_update_index;
+	/* Length of the OID keys in the 'o' section */
+	int object_id_len;
+	int version;
+
+	struct reftable_reader_offsets ref_offsets;
+	struct reftable_reader_offsets obj_offsets;
+	struct reftable_reader_offsets log_offsets;
+};
+
+int init_reader(struct reftable_reader *r, struct reftable_block_source *source,
+		const char *name);
+void reader_close(struct reftable_reader *r);
+const char *reader_name(struct reftable_reader *r);
+
+/* initialize a block reader to read from `r` */
+int reader_init_block_reader(struct reftable_reader *r, struct block_reader *br,
+			     uint64_t next_off, uint8_t want_typ);
+
+#endif
diff --git a/reftable/readwrite_test.c b/reftable/readwrite_test.c
new file mode 100644
index 0000000..70c7aed
--- /dev/null
+++ b/reftable/readwrite_test.c
@@ -0,0 +1,687 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "system.h"
+
+#include "basics.h"
+#include "block.h"
+#include "blocksource.h"
+#include "constants.h"
+#include "reader.h"
+#include "record.h"
+#include "test_framework.h"
+#include "reftable-tests.h"
+#include "reftable-writer.h"
+
+static const int update_index = 5;
+
+static void test_buffer(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_block_source source = { NULL };
+	struct reftable_block out = { NULL };
+	int n;
+	uint8_t in[] = "hello";
+	strbuf_add(&buf, in, sizeof(in));
+	block_source_from_strbuf(&source, &buf);
+	EXPECT(block_source_size(&source) == 6);
+	n = block_source_read_block(&source, &out, 0, sizeof(in));
+	EXPECT(n == sizeof(in));
+	EXPECT(!memcmp(in, out.data, n));
+	reftable_block_done(&out);
+
+	n = block_source_read_block(&source, &out, 1, 2);
+	EXPECT(n == 2);
+	EXPECT(!memcmp(out.data, "el", 2));
+
+	reftable_block_done(&out);
+	block_source_close(&source);
+	strbuf_release(&buf);
+}
+
+static void write_table(char ***names, struct strbuf *buf, int N,
+			int block_size, uint32_t hash_id)
+{
+	struct reftable_write_options opts = {
+		.block_size = block_size,
+		.hash_id = hash_id,
+	};
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, buf, &opts);
+	struct reftable_ref_record ref = { NULL };
+	int i = 0, n;
+	struct reftable_log_record log = { NULL };
+	const struct reftable_stats *stats = NULL;
+	*names = reftable_calloc(sizeof(char *) * (N + 1));
+	reftable_writer_set_limits(w, update_index, update_index);
+	for (i = 0; i < N; i++) {
+		uint8_t hash[GIT_SHA256_RAWSZ] = { 0 };
+		char name[100];
+		int n;
+
+		set_test_hash(hash, i);
+
+		snprintf(name, sizeof(name), "refs/heads/branch%02d", i);
+
+		ref.refname = name;
+		ref.update_index = update_index;
+		ref.value_type = REFTABLE_REF_VAL1;
+		ref.value.val1 = hash;
+		(*names)[i] = xstrdup(name);
+
+		n = reftable_writer_add_ref(w, &ref);
+		EXPECT(n == 0);
+	}
+
+	for (i = 0; i < N; i++) {
+		uint8_t hash[GIT_SHA256_RAWSZ] = { 0 };
+		char name[100];
+		int n;
+
+		set_test_hash(hash, i);
+
+		snprintf(name, sizeof(name), "refs/heads/branch%02d", i);
+
+		log.refname = name;
+		log.update_index = update_index;
+		log.value_type = REFTABLE_LOG_UPDATE;
+		log.value.update.new_hash = hash;
+		log.value.update.message = "message";
+
+		n = reftable_writer_add_log(w, &log);
+		EXPECT(n == 0);
+	}
+
+	n = reftable_writer_close(w);
+	EXPECT(n == 0);
+
+	stats = writer_stats(w);
+	for (i = 0; i < stats->ref_stats.blocks; i++) {
+		int off = i * opts.block_size;
+		if (off == 0) {
+			off = header_size(
+				(hash_id == GIT_SHA256_FORMAT_ID) ? 2 : 1);
+		}
+		EXPECT(buf->buf[off] == 'r');
+	}
+
+	EXPECT(stats->log_stats.blocks > 0);
+	reftable_writer_free(w);
+}
+
+static void test_log_buffer_size(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_write_options opts = {
+		.block_size = 4096,
+	};
+	int err;
+	int i;
+	struct reftable_log_record
+		log = { .refname = "refs/heads/master",
+			.update_index = 0xa,
+			.value_type = REFTABLE_LOG_UPDATE,
+			.value = { .update = {
+					   .name = "Han-Wen Nienhuys",
+					   .email = "hanwen@google.com",
+					   .tz_offset = 100,
+					   .time = 0x5e430672,
+					   .message = "commit: 9\n",
+				   } } };
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+
+	/* This tests buffer extension for log compression. Must use a random
+	   hash, to ensure that the compressed part is larger than the original.
+	*/
+	uint8_t hash1[GIT_SHA1_RAWSZ], hash2[GIT_SHA1_RAWSZ];
+	for (i = 0; i < GIT_SHA1_RAWSZ; i++) {
+		hash1[i] = (uint8_t)(rand() % 256);
+		hash2[i] = (uint8_t)(rand() % 256);
+	}
+	log.value.update.old_hash = hash1;
+	log.value.update.new_hash = hash2;
+	reftable_writer_set_limits(w, update_index, update_index);
+	err = reftable_writer_add_log(w, &log);
+	EXPECT_ERR(err);
+	err = reftable_writer_close(w);
+	EXPECT_ERR(err);
+	reftable_writer_free(w);
+	strbuf_release(&buf);
+}
+
+static void test_log_overflow(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	char msg[256] = { 0 };
+	struct reftable_write_options opts = {
+		.block_size = ARRAY_SIZE(msg),
+	};
+	int err;
+	struct reftable_log_record
+		log = { .refname = "refs/heads/master",
+			.update_index = 0xa,
+			.value_type = REFTABLE_LOG_UPDATE,
+			.value = { .update = {
+					   .name = "Han-Wen Nienhuys",
+					   .email = "hanwen@google.com",
+					   .tz_offset = 100,
+					   .time = 0x5e430672,
+					   .message = msg,
+				   } } };
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+
+	uint8_t hash1[GIT_SHA1_RAWSZ]  = {1}, hash2[GIT_SHA1_RAWSZ] = { 2 };
+
+	memset(msg, 'x', sizeof(msg) - 1);
+	log.value.update.old_hash = hash1;
+	log.value.update.new_hash = hash2;
+	reftable_writer_set_limits(w, update_index, update_index);
+	err = reftable_writer_add_log(w, &log);
+	EXPECT(err == REFTABLE_ENTRY_TOO_BIG_ERROR);
+	reftable_writer_free(w);
+	strbuf_release(&buf);
+}
+
+static void test_log_write_read(void)
+{
+	int N = 2;
+	char **names = reftable_calloc(sizeof(char *) * (N + 1));
+	int err;
+	struct reftable_write_options opts = {
+		.block_size = 256,
+	};
+	struct reftable_ref_record ref = { NULL };
+	int i = 0;
+	struct reftable_log_record log = { NULL };
+	int n;
+	struct reftable_iterator it = { NULL };
+	struct reftable_reader rd = { NULL };
+	struct reftable_block_source source = { NULL };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+	const struct reftable_stats *stats = NULL;
+	reftable_writer_set_limits(w, 0, N);
+	for (i = 0; i < N; i++) {
+		char name[256];
+		struct reftable_ref_record ref = { NULL };
+		snprintf(name, sizeof(name), "b%02d%0*d", i, 130, 7);
+		names[i] = xstrdup(name);
+		ref.refname = name;
+		ref.update_index = i;
+
+		err = reftable_writer_add_ref(w, &ref);
+		EXPECT_ERR(err);
+	}
+	for (i = 0; i < N; i++) {
+		uint8_t hash1[GIT_SHA1_RAWSZ], hash2[GIT_SHA1_RAWSZ];
+		struct reftable_log_record log = { NULL };
+		set_test_hash(hash1, i);
+		set_test_hash(hash2, i + 1);
+
+		log.refname = names[i];
+		log.update_index = i;
+		log.value_type = REFTABLE_LOG_UPDATE;
+		log.value.update.old_hash = hash1;
+		log.value.update.new_hash = hash2;
+
+		err = reftable_writer_add_log(w, &log);
+		EXPECT_ERR(err);
+	}
+
+	n = reftable_writer_close(w);
+	EXPECT(n == 0);
+
+	stats = writer_stats(w);
+	EXPECT(stats->log_stats.blocks > 0);
+	reftable_writer_free(w);
+	w = NULL;
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.log");
+	EXPECT_ERR(err);
+
+	err = reftable_reader_seek_ref(&rd, &it, names[N - 1]);
+	EXPECT_ERR(err);
+
+	err = reftable_iterator_next_ref(&it, &ref);
+	EXPECT_ERR(err);
+
+	/* end of iteration. */
+	err = reftable_iterator_next_ref(&it, &ref);
+	EXPECT(0 < err);
+
+	reftable_iterator_destroy(&it);
+	reftable_ref_record_release(&ref);
+
+	err = reftable_reader_seek_log(&rd, &it, "");
+	EXPECT_ERR(err);
+
+	i = 0;
+	while (1) {
+		int err = reftable_iterator_next_log(&it, &log);
+		if (err > 0) {
+			break;
+		}
+
+		EXPECT_ERR(err);
+		EXPECT_STREQ(names[i], log.refname);
+		EXPECT(i == log.update_index);
+		i++;
+		reftable_log_record_release(&log);
+	}
+
+	EXPECT(i == N);
+	reftable_iterator_destroy(&it);
+
+	/* cleanup. */
+	strbuf_release(&buf);
+	free_names(names);
+	reader_close(&rd);
+}
+
+static void test_table_read_write_sequential(void)
+{
+	char **names;
+	struct strbuf buf = STRBUF_INIT;
+	int N = 50;
+	struct reftable_iterator it = { NULL };
+	struct reftable_block_source source = { NULL };
+	struct reftable_reader rd = { NULL };
+	int err = 0;
+	int j = 0;
+
+	write_table(&names, &buf, N, 256, GIT_SHA1_FORMAT_ID);
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.ref");
+	EXPECT_ERR(err);
+
+	err = reftable_reader_seek_ref(&rd, &it, "");
+	EXPECT_ERR(err);
+
+	while (1) {
+		struct reftable_ref_record ref = { NULL };
+		int r = reftable_iterator_next_ref(&it, &ref);
+		EXPECT(r >= 0);
+		if (r > 0) {
+			break;
+		}
+		EXPECT(0 == strcmp(names[j], ref.refname));
+		EXPECT(update_index == ref.update_index);
+
+		j++;
+		reftable_ref_record_release(&ref);
+	}
+	EXPECT(j == N);
+	reftable_iterator_destroy(&it);
+	strbuf_release(&buf);
+	free_names(names);
+
+	reader_close(&rd);
+}
+
+static void test_table_write_small_table(void)
+{
+	char **names;
+	struct strbuf buf = STRBUF_INIT;
+	int N = 1;
+	write_table(&names, &buf, N, 4096, GIT_SHA1_FORMAT_ID);
+	EXPECT(buf.len < 200);
+	strbuf_release(&buf);
+	free_names(names);
+}
+
+static void test_table_read_api(void)
+{
+	char **names;
+	struct strbuf buf = STRBUF_INIT;
+	int N = 50;
+	struct reftable_reader rd = { NULL };
+	struct reftable_block_source source = { NULL };
+	int err;
+	int i;
+	struct reftable_log_record log = { NULL };
+	struct reftable_iterator it = { NULL };
+
+	write_table(&names, &buf, N, 256, GIT_SHA1_FORMAT_ID);
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.ref");
+	EXPECT_ERR(err);
+
+	err = reftable_reader_seek_ref(&rd, &it, names[0]);
+	EXPECT_ERR(err);
+
+	err = reftable_iterator_next_log(&it, &log);
+	EXPECT(err == REFTABLE_API_ERROR);
+
+	strbuf_release(&buf);
+	for (i = 0; i < N; i++) {
+		reftable_free(names[i]);
+	}
+	reftable_iterator_destroy(&it);
+	reftable_free(names);
+	reader_close(&rd);
+	strbuf_release(&buf);
+}
+
+static void test_table_read_write_seek(int index, int hash_id)
+{
+	char **names;
+	struct strbuf buf = STRBUF_INIT;
+	int N = 50;
+	struct reftable_reader rd = { NULL };
+	struct reftable_block_source source = { NULL };
+	int err;
+	int i = 0;
+
+	struct reftable_iterator it = { NULL };
+	struct strbuf pastLast = STRBUF_INIT;
+	struct reftable_ref_record ref = { NULL };
+
+	write_table(&names, &buf, N, 256, hash_id);
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.ref");
+	EXPECT_ERR(err);
+	EXPECT(hash_id == reftable_reader_hash_id(&rd));
+
+	if (!index) {
+		rd.ref_offsets.index_offset = 0;
+	} else {
+		EXPECT(rd.ref_offsets.index_offset > 0);
+	}
+
+	for (i = 1; i < N; i++) {
+		int err = reftable_reader_seek_ref(&rd, &it, names[i]);
+		EXPECT_ERR(err);
+		err = reftable_iterator_next_ref(&it, &ref);
+		EXPECT_ERR(err);
+		EXPECT(0 == strcmp(names[i], ref.refname));
+		EXPECT(REFTABLE_REF_VAL1 == ref.value_type);
+		EXPECT(i == ref.value.val1[0]);
+
+		reftable_ref_record_release(&ref);
+		reftable_iterator_destroy(&it);
+	}
+
+	strbuf_addstr(&pastLast, names[N - 1]);
+	strbuf_addstr(&pastLast, "/");
+
+	err = reftable_reader_seek_ref(&rd, &it, pastLast.buf);
+	if (err == 0) {
+		struct reftable_ref_record ref = { NULL };
+		int err = reftable_iterator_next_ref(&it, &ref);
+		EXPECT(err > 0);
+	} else {
+		EXPECT(err > 0);
+	}
+
+	strbuf_release(&pastLast);
+	reftable_iterator_destroy(&it);
+
+	strbuf_release(&buf);
+	for (i = 0; i < N; i++) {
+		reftable_free(names[i]);
+	}
+	reftable_free(names);
+	reader_close(&rd);
+}
+
+static void test_table_read_write_seek_linear(void)
+{
+	test_table_read_write_seek(0, GIT_SHA1_FORMAT_ID);
+}
+
+static void test_table_read_write_seek_linear_sha256(void)
+{
+	test_table_read_write_seek(0, GIT_SHA256_FORMAT_ID);
+}
+
+static void test_table_read_write_seek_index(void)
+{
+	test_table_read_write_seek(1, GIT_SHA1_FORMAT_ID);
+}
+
+static void test_table_refs_for(int indexed)
+{
+	int N = 50;
+	char **want_names = reftable_calloc(sizeof(char *) * (N + 1));
+	int want_names_len = 0;
+	uint8_t want_hash[GIT_SHA1_RAWSZ];
+
+	struct reftable_write_options opts = {
+		.block_size = 256,
+	};
+	struct reftable_ref_record ref = { NULL };
+	int i = 0;
+	int n;
+	int err;
+	struct reftable_reader rd;
+	struct reftable_block_source source = { NULL };
+
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+
+	struct reftable_iterator it = { NULL };
+	int j;
+
+	set_test_hash(want_hash, 4);
+
+	for (i = 0; i < N; i++) {
+		uint8_t hash[GIT_SHA1_RAWSZ];
+		char fill[51] = { 0 };
+		char name[100];
+		uint8_t hash1[GIT_SHA1_RAWSZ];
+		uint8_t hash2[GIT_SHA1_RAWSZ];
+		struct reftable_ref_record ref = { NULL };
+
+		memset(hash, i, sizeof(hash));
+		memset(fill, 'x', 50);
+		/* Put the variable part in the start */
+		snprintf(name, sizeof(name), "br%02d%s", i, fill);
+		name[40] = 0;
+		ref.refname = name;
+
+		set_test_hash(hash1, i / 4);
+		set_test_hash(hash2, 3 + i / 4);
+		ref.value_type = REFTABLE_REF_VAL2;
+		ref.value.val2.value = hash1;
+		ref.value.val2.target_value = hash2;
+
+		/* 80 bytes / entry, so 3 entries per block. Yields 17
+		 */
+		/* blocks. */
+		n = reftable_writer_add_ref(w, &ref);
+		EXPECT(n == 0);
+
+		if (!memcmp(hash1, want_hash, GIT_SHA1_RAWSZ) ||
+		    !memcmp(hash2, want_hash, GIT_SHA1_RAWSZ)) {
+			want_names[want_names_len++] = xstrdup(name);
+		}
+	}
+
+	n = reftable_writer_close(w);
+	EXPECT(n == 0);
+
+	reftable_writer_free(w);
+	w = NULL;
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.ref");
+	EXPECT_ERR(err);
+	if (!indexed) {
+		rd.obj_offsets.is_present = 0;
+	}
+
+	err = reftable_reader_seek_ref(&rd, &it, "");
+	EXPECT_ERR(err);
+	reftable_iterator_destroy(&it);
+
+	err = reftable_reader_refs_for(&rd, &it, want_hash);
+	EXPECT_ERR(err);
+
+	j = 0;
+	while (1) {
+		int err = reftable_iterator_next_ref(&it, &ref);
+		EXPECT(err >= 0);
+		if (err > 0) {
+			break;
+		}
+
+		EXPECT(j < want_names_len);
+		EXPECT(0 == strcmp(ref.refname, want_names[j]));
+		j++;
+		reftable_ref_record_release(&ref);
+	}
+	EXPECT(j == want_names_len);
+
+	strbuf_release(&buf);
+	free_names(want_names);
+	reftable_iterator_destroy(&it);
+	reader_close(&rd);
+}
+
+static void test_table_refs_for_no_index(void)
+{
+	test_table_refs_for(0);
+}
+
+static void test_table_refs_for_obj_index(void)
+{
+	test_table_refs_for(1);
+}
+
+static void test_write_empty_table(void)
+{
+	struct reftable_write_options opts = { 0 };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+	struct reftable_block_source source = { NULL };
+	struct reftable_reader *rd = NULL;
+	struct reftable_ref_record rec = { NULL };
+	struct reftable_iterator it = { NULL };
+	int err;
+
+	reftable_writer_set_limits(w, 1, 1);
+
+	err = reftable_writer_close(w);
+	EXPECT(err == REFTABLE_EMPTY_TABLE_ERROR);
+	reftable_writer_free(w);
+
+	EXPECT(buf.len == header_size(1) + footer_size(1));
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = reftable_new_reader(&rd, &source, "filename");
+	EXPECT_ERR(err);
+
+	err = reftable_reader_seek_ref(rd, &it, "");
+	EXPECT_ERR(err);
+
+	err = reftable_iterator_next_ref(&it, &rec);
+	EXPECT(err > 0);
+
+	reftable_iterator_destroy(&it);
+	reftable_reader_free(rd);
+	strbuf_release(&buf);
+}
+
+static void test_write_key_order(void)
+{
+	struct reftable_write_options opts = { 0 };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+	struct reftable_ref_record refs[2] = {
+		{
+			.refname = "b",
+			.update_index = 1,
+			.value_type = REFTABLE_REF_SYMREF,
+			.value = {
+				.symref = "target",
+			},
+		}, {
+			.refname = "a",
+			.update_index = 1,
+			.value_type = REFTABLE_REF_SYMREF,
+			.value = {
+				.symref = "target",
+			},
+		}
+	};
+	int err;
+
+	reftable_writer_set_limits(w, 1, 1);
+	err = reftable_writer_add_ref(w, &refs[0]);
+	EXPECT_ERR(err);
+	err = reftable_writer_add_ref(w, &refs[1]);
+	printf("%d\n", err);
+	EXPECT(err == REFTABLE_API_ERROR);
+	reftable_writer_close(w);
+	reftable_writer_free(w);
+	strbuf_release(&buf);
+}
+
+static void test_corrupt_table_empty(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_block_source source = { NULL };
+	struct reftable_reader rd = { NULL };
+	int err;
+
+	block_source_from_strbuf(&source, &buf);
+	err = init_reader(&rd, &source, "file.log");
+	EXPECT(err == REFTABLE_FORMAT_ERROR);
+}
+
+static void test_corrupt_table(void)
+{
+	uint8_t zeros[1024] = { 0 };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_block_source source = { NULL };
+	struct reftable_reader rd = { NULL };
+	int err;
+	strbuf_add(&buf, zeros, sizeof(zeros));
+
+	block_source_from_strbuf(&source, &buf);
+	err = init_reader(&rd, &source, "file.log");
+	EXPECT(err == REFTABLE_FORMAT_ERROR);
+	strbuf_release(&buf);
+}
+
+int readwrite_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_corrupt_table);
+	RUN_TEST(test_corrupt_table_empty);
+	RUN_TEST(test_log_write_read);
+	RUN_TEST(test_write_key_order);
+	RUN_TEST(test_table_read_write_seek_linear_sha256);
+	RUN_TEST(test_log_buffer_size);
+	RUN_TEST(test_table_write_small_table);
+	RUN_TEST(test_buffer);
+	RUN_TEST(test_table_read_api);
+	RUN_TEST(test_table_read_write_sequential);
+	RUN_TEST(test_table_read_write_seek_linear);
+	RUN_TEST(test_table_read_write_seek_index);
+	RUN_TEST(test_table_refs_for_no_index);
+	RUN_TEST(test_table_refs_for_obj_index);
+	RUN_TEST(test_write_empty_table);
+	RUN_TEST(test_log_overflow);
+	return 0;
+}
diff --git a/reftable/record.c b/reftable/record.c
new file mode 100644
index 0000000..6a5dac3
--- /dev/null
+++ b/reftable/record.c
@@ -0,0 +1,1212 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+/* record.c - methods for different types of records. */
+
+#include "record.h"
+
+#include "system.h"
+#include "constants.h"
+#include "reftable-error.h"
+#include "basics.h"
+
+int get_var_int(uint64_t *dest, struct string_view *in)
+{
+	int ptr = 0;
+	uint64_t val;
+
+	if (in->len == 0)
+		return -1;
+	val = in->buf[ptr] & 0x7f;
+
+	while (in->buf[ptr] & 0x80) {
+		ptr++;
+		if (ptr > in->len) {
+			return -1;
+		}
+		val = (val + 1) << 7 | (uint64_t)(in->buf[ptr] & 0x7f);
+	}
+
+	*dest = val;
+	return ptr + 1;
+}
+
+int put_var_int(struct string_view *dest, uint64_t val)
+{
+	uint8_t buf[10] = { 0 };
+	int i = 9;
+	int n = 0;
+	buf[i] = (uint8_t)(val & 0x7f);
+	i--;
+	while (1) {
+		val >>= 7;
+		if (!val) {
+			break;
+		}
+		val--;
+		buf[i] = 0x80 | (uint8_t)(val & 0x7f);
+		i--;
+	}
+
+	n = sizeof(buf) - i - 1;
+	if (dest->len < n)
+		return -1;
+	memcpy(dest->buf, &buf[i + 1], n);
+	return n;
+}
+
+int reftable_is_block_type(uint8_t typ)
+{
+	switch (typ) {
+	case BLOCK_TYPE_REF:
+	case BLOCK_TYPE_LOG:
+	case BLOCK_TYPE_OBJ:
+	case BLOCK_TYPE_INDEX:
+		return 1;
+	}
+	return 0;
+}
+
+uint8_t *reftable_ref_record_val1(struct reftable_ref_record *rec)
+{
+	switch (rec->value_type) {
+	case REFTABLE_REF_VAL1:
+		return rec->value.val1;
+	case REFTABLE_REF_VAL2:
+		return rec->value.val2.value;
+	default:
+		return NULL;
+	}
+}
+
+uint8_t *reftable_ref_record_val2(struct reftable_ref_record *rec)
+{
+	switch (rec->value_type) {
+	case REFTABLE_REF_VAL2:
+		return rec->value.val2.target_value;
+	default:
+		return NULL;
+	}
+}
+
+static int decode_string(struct strbuf *dest, struct string_view in)
+{
+	int start_len = in.len;
+	uint64_t tsize = 0;
+	int n = get_var_int(&tsize, &in);
+	if (n <= 0)
+		return -1;
+	string_view_consume(&in, n);
+	if (in.len < tsize)
+		return -1;
+
+	strbuf_reset(dest);
+	strbuf_add(dest, in.buf, tsize);
+	string_view_consume(&in, tsize);
+
+	return start_len - in.len;
+}
+
+static int encode_string(char *str, struct string_view s)
+{
+	struct string_view start = s;
+	int l = strlen(str);
+	int n = put_var_int(&s, l);
+	if (n < 0)
+		return -1;
+	string_view_consume(&s, n);
+	if (s.len < l)
+		return -1;
+	memcpy(s.buf, str, l);
+	string_view_consume(&s, l);
+
+	return start.len - s.len;
+}
+
+int reftable_encode_key(int *restart, struct string_view dest,
+			struct strbuf prev_key, struct strbuf key,
+			uint8_t extra)
+{
+	struct string_view start = dest;
+	int prefix_len = common_prefix_size(&prev_key, &key);
+	uint64_t suffix_len = key.len - prefix_len;
+	int n = put_var_int(&dest, (uint64_t)prefix_len);
+	if (n < 0)
+		return -1;
+	string_view_consume(&dest, n);
+
+	*restart = (prefix_len == 0);
+
+	n = put_var_int(&dest, suffix_len << 3 | (uint64_t)extra);
+	if (n < 0)
+		return -1;
+	string_view_consume(&dest, n);
+
+	if (dest.len < suffix_len)
+		return -1;
+	memcpy(dest.buf, key.buf + prefix_len, suffix_len);
+	string_view_consume(&dest, suffix_len);
+
+	return start.len - dest.len;
+}
+
+int reftable_decode_key(struct strbuf *key, uint8_t *extra,
+			struct strbuf last_key, struct string_view in)
+{
+	int start_len = in.len;
+	uint64_t prefix_len = 0;
+	uint64_t suffix_len = 0;
+	int n = get_var_int(&prefix_len, &in);
+	if (n < 0)
+		return -1;
+	string_view_consume(&in, n);
+
+	if (prefix_len > last_key.len)
+		return -1;
+
+	n = get_var_int(&suffix_len, &in);
+	if (n <= 0)
+		return -1;
+	string_view_consume(&in, n);
+
+	*extra = (uint8_t)(suffix_len & 0x7);
+	suffix_len >>= 3;
+
+	if (in.len < suffix_len)
+		return -1;
+
+	strbuf_reset(key);
+	strbuf_add(key, last_key.buf, prefix_len);
+	strbuf_add(key, in.buf, suffix_len);
+	string_view_consume(&in, suffix_len);
+
+	return start_len - in.len;
+}
+
+static void reftable_ref_record_key(const void *r, struct strbuf *dest)
+{
+	const struct reftable_ref_record *rec =
+		(const struct reftable_ref_record *)r;
+	strbuf_reset(dest);
+	strbuf_addstr(dest, rec->refname);
+}
+
+static void reftable_ref_record_copy_from(void *rec, const void *src_rec,
+					  int hash_size)
+{
+	struct reftable_ref_record *ref = rec;
+	const struct reftable_ref_record *src = src_rec;
+	assert(hash_size > 0);
+
+	/* This is simple and correct, but we could probably reuse the hash
+	 * fields. */
+	reftable_ref_record_release(ref);
+	if (src->refname) {
+		ref->refname = xstrdup(src->refname);
+	}
+	ref->update_index = src->update_index;
+	ref->value_type = src->value_type;
+	switch (src->value_type) {
+	case REFTABLE_REF_DELETION:
+		break;
+	case REFTABLE_REF_VAL1:
+		ref->value.val1 = reftable_malloc(hash_size);
+		memcpy(ref->value.val1, src->value.val1, hash_size);
+		break;
+	case REFTABLE_REF_VAL2:
+		ref->value.val2.value = reftable_malloc(hash_size);
+		memcpy(ref->value.val2.value, src->value.val2.value, hash_size);
+		ref->value.val2.target_value = reftable_malloc(hash_size);
+		memcpy(ref->value.val2.target_value,
+		       src->value.val2.target_value, hash_size);
+		break;
+	case REFTABLE_REF_SYMREF:
+		ref->value.symref = xstrdup(src->value.symref);
+		break;
+	}
+}
+
+static char hexdigit(int c)
+{
+	if (c <= 9)
+		return '0' + c;
+	return 'a' + (c - 10);
+}
+
+static void hex_format(char *dest, uint8_t *src, int hash_size)
+{
+	assert(hash_size > 0);
+	if (src) {
+		int i = 0;
+		for (i = 0; i < hash_size; i++) {
+			dest[2 * i] = hexdigit(src[i] >> 4);
+			dest[2 * i + 1] = hexdigit(src[i] & 0xf);
+		}
+		dest[2 * hash_size] = 0;
+	}
+}
+
+void reftable_ref_record_print(struct reftable_ref_record *ref,
+			       uint32_t hash_id)
+{
+	char hex[2 * GIT_SHA256_RAWSZ + 1] = { 0 }; /* BUG */
+	printf("ref{%s(%" PRIu64 ") ", ref->refname, ref->update_index);
+	switch (ref->value_type) {
+	case REFTABLE_REF_SYMREF:
+		printf("=> %s", ref->value.symref);
+		break;
+	case REFTABLE_REF_VAL2:
+		hex_format(hex, ref->value.val2.value, hash_size(hash_id));
+		printf("val 2 %s", hex);
+		hex_format(hex, ref->value.val2.target_value,
+			   hash_size(hash_id));
+		printf("(T %s)", hex);
+		break;
+	case REFTABLE_REF_VAL1:
+		hex_format(hex, ref->value.val1, hash_size(hash_id));
+		printf("val 1 %s", hex);
+		break;
+	case REFTABLE_REF_DELETION:
+		printf("delete");
+		break;
+	}
+	printf("}\n");
+}
+
+static void reftable_ref_record_release_void(void *rec)
+{
+	reftable_ref_record_release(rec);
+}
+
+void reftable_ref_record_release(struct reftable_ref_record *ref)
+{
+	switch (ref->value_type) {
+	case REFTABLE_REF_SYMREF:
+		reftable_free(ref->value.symref);
+		break;
+	case REFTABLE_REF_VAL2:
+		reftable_free(ref->value.val2.target_value);
+		reftable_free(ref->value.val2.value);
+		break;
+	case REFTABLE_REF_VAL1:
+		reftable_free(ref->value.val1);
+		break;
+	case REFTABLE_REF_DELETION:
+		break;
+	default:
+		abort();
+	}
+
+	reftable_free(ref->refname);
+	memset(ref, 0, sizeof(struct reftable_ref_record));
+}
+
+static uint8_t reftable_ref_record_val_type(const void *rec)
+{
+	const struct reftable_ref_record *r =
+		(const struct reftable_ref_record *)rec;
+	return r->value_type;
+}
+
+static int reftable_ref_record_encode(const void *rec, struct string_view s,
+				      int hash_size)
+{
+	const struct reftable_ref_record *r =
+		(const struct reftable_ref_record *)rec;
+	struct string_view start = s;
+	int n = put_var_int(&s, r->update_index);
+	assert(hash_size > 0);
+	if (n < 0)
+		return -1;
+	string_view_consume(&s, n);
+
+	switch (r->value_type) {
+	case REFTABLE_REF_SYMREF:
+		n = encode_string(r->value.symref, s);
+		if (n < 0) {
+			return -1;
+		}
+		string_view_consume(&s, n);
+		break;
+	case REFTABLE_REF_VAL2:
+		if (s.len < 2 * hash_size) {
+			return -1;
+		}
+		memcpy(s.buf, r->value.val2.value, hash_size);
+		string_view_consume(&s, hash_size);
+		memcpy(s.buf, r->value.val2.target_value, hash_size);
+		string_view_consume(&s, hash_size);
+		break;
+	case REFTABLE_REF_VAL1:
+		if (s.len < hash_size) {
+			return -1;
+		}
+		memcpy(s.buf, r->value.val1, hash_size);
+		string_view_consume(&s, hash_size);
+		break;
+	case REFTABLE_REF_DELETION:
+		break;
+	default:
+		abort();
+	}
+
+	return start.len - s.len;
+}
+
+static int reftable_ref_record_decode(void *rec, struct strbuf key,
+				      uint8_t val_type, struct string_view in,
+				      int hash_size)
+{
+	struct reftable_ref_record *r = rec;
+	struct string_view start = in;
+	uint64_t update_index = 0;
+	int n = get_var_int(&update_index, &in);
+	if (n < 0)
+		return n;
+	string_view_consume(&in, n);
+
+	reftable_ref_record_release(r);
+
+	assert(hash_size > 0);
+
+	r->refname = reftable_realloc(r->refname, key.len + 1);
+	memcpy(r->refname, key.buf, key.len);
+	r->update_index = update_index;
+	r->refname[key.len] = 0;
+	r->value_type = val_type;
+	switch (val_type) {
+	case REFTABLE_REF_VAL1:
+		if (in.len < hash_size) {
+			return -1;
+		}
+
+		r->value.val1 = reftable_malloc(hash_size);
+		memcpy(r->value.val1, in.buf, hash_size);
+		string_view_consume(&in, hash_size);
+		break;
+
+	case REFTABLE_REF_VAL2:
+		if (in.len < 2 * hash_size) {
+			return -1;
+		}
+
+		r->value.val2.value = reftable_malloc(hash_size);
+		memcpy(r->value.val2.value, in.buf, hash_size);
+		string_view_consume(&in, hash_size);
+
+		r->value.val2.target_value = reftable_malloc(hash_size);
+		memcpy(r->value.val2.target_value, in.buf, hash_size);
+		string_view_consume(&in, hash_size);
+		break;
+
+	case REFTABLE_REF_SYMREF: {
+		struct strbuf dest = STRBUF_INIT;
+		int n = decode_string(&dest, in);
+		if (n < 0) {
+			return -1;
+		}
+		string_view_consume(&in, n);
+		r->value.symref = dest.buf;
+	} break;
+
+	case REFTABLE_REF_DELETION:
+		break;
+	default:
+		abort();
+		break;
+	}
+
+	return start.len - in.len;
+}
+
+static int reftable_ref_record_is_deletion_void(const void *p)
+{
+	return reftable_ref_record_is_deletion(
+		(const struct reftable_ref_record *)p);
+}
+
+static struct reftable_record_vtable reftable_ref_record_vtable = {
+	.key = &reftable_ref_record_key,
+	.type = BLOCK_TYPE_REF,
+	.copy_from = &reftable_ref_record_copy_from,
+	.val_type = &reftable_ref_record_val_type,
+	.encode = &reftable_ref_record_encode,
+	.decode = &reftable_ref_record_decode,
+	.release = &reftable_ref_record_release_void,
+	.is_deletion = &reftable_ref_record_is_deletion_void,
+};
+
+static void reftable_obj_record_key(const void *r, struct strbuf *dest)
+{
+	const struct reftable_obj_record *rec =
+		(const struct reftable_obj_record *)r;
+	strbuf_reset(dest);
+	strbuf_add(dest, rec->hash_prefix, rec->hash_prefix_len);
+}
+
+static void reftable_obj_record_release(void *rec)
+{
+	struct reftable_obj_record *obj = rec;
+	FREE_AND_NULL(obj->hash_prefix);
+	FREE_AND_NULL(obj->offsets);
+	memset(obj, 0, sizeof(struct reftable_obj_record));
+}
+
+static void reftable_obj_record_copy_from(void *rec, const void *src_rec,
+					  int hash_size)
+{
+	struct reftable_obj_record *obj = rec;
+	const struct reftable_obj_record *src =
+		(const struct reftable_obj_record *)src_rec;
+
+	reftable_obj_record_release(obj);
+	*obj = *src;
+	obj->hash_prefix = reftable_malloc(obj->hash_prefix_len);
+	memcpy(obj->hash_prefix, src->hash_prefix, obj->hash_prefix_len);
+
+	obj->offsets = reftable_malloc(obj->offset_len * sizeof(uint64_t));
+	COPY_ARRAY(obj->offsets, src->offsets, obj->offset_len);
+}
+
+static uint8_t reftable_obj_record_val_type(const void *rec)
+{
+	const struct reftable_obj_record *r = rec;
+	if (r->offset_len > 0 && r->offset_len < 8)
+		return r->offset_len;
+	return 0;
+}
+
+static int reftable_obj_record_encode(const void *rec, struct string_view s,
+				      int hash_size)
+{
+	const struct reftable_obj_record *r = rec;
+	struct string_view start = s;
+	int i = 0;
+	int n = 0;
+	uint64_t last = 0;
+	if (r->offset_len == 0 || r->offset_len >= 8) {
+		n = put_var_int(&s, r->offset_len);
+		if (n < 0) {
+			return -1;
+		}
+		string_view_consume(&s, n);
+	}
+	if (r->offset_len == 0)
+		return start.len - s.len;
+	n = put_var_int(&s, r->offsets[0]);
+	if (n < 0)
+		return -1;
+	string_view_consume(&s, n);
+
+	last = r->offsets[0];
+	for (i = 1; i < r->offset_len; i++) {
+		int n = put_var_int(&s, r->offsets[i] - last);
+		if (n < 0) {
+			return -1;
+		}
+		string_view_consume(&s, n);
+		last = r->offsets[i];
+	}
+	return start.len - s.len;
+}
+
+static int reftable_obj_record_decode(void *rec, struct strbuf key,
+				      uint8_t val_type, struct string_view in,
+				      int hash_size)
+{
+	struct string_view start = in;
+	struct reftable_obj_record *r = rec;
+	uint64_t count = val_type;
+	int n = 0;
+	uint64_t last;
+	int j;
+	r->hash_prefix = reftable_malloc(key.len);
+	memcpy(r->hash_prefix, key.buf, key.len);
+	r->hash_prefix_len = key.len;
+
+	if (val_type == 0) {
+		n = get_var_int(&count, &in);
+		if (n < 0) {
+			return n;
+		}
+
+		string_view_consume(&in, n);
+	}
+
+	r->offsets = NULL;
+	r->offset_len = 0;
+	if (count == 0)
+		return start.len - in.len;
+
+	r->offsets = reftable_malloc(count * sizeof(uint64_t));
+	r->offset_len = count;
+
+	n = get_var_int(&r->offsets[0], &in);
+	if (n < 0)
+		return n;
+	string_view_consume(&in, n);
+
+	last = r->offsets[0];
+	j = 1;
+	while (j < count) {
+		uint64_t delta = 0;
+		int n = get_var_int(&delta, &in);
+		if (n < 0) {
+			return n;
+		}
+		string_view_consume(&in, n);
+
+		last = r->offsets[j] = (delta + last);
+		j++;
+	}
+	return start.len - in.len;
+}
+
+static int not_a_deletion(const void *p)
+{
+	return 0;
+}
+
+static struct reftable_record_vtable reftable_obj_record_vtable = {
+	.key = &reftable_obj_record_key,
+	.type = BLOCK_TYPE_OBJ,
+	.copy_from = &reftable_obj_record_copy_from,
+	.val_type = &reftable_obj_record_val_type,
+	.encode = &reftable_obj_record_encode,
+	.decode = &reftable_obj_record_decode,
+	.release = &reftable_obj_record_release,
+	.is_deletion = not_a_deletion,
+};
+
+void reftable_log_record_print(struct reftable_log_record *log,
+			       uint32_t hash_id)
+{
+	char hex[GIT_SHA256_RAWSZ + 1] = { 0 };
+
+	switch (log->value_type) {
+	case REFTABLE_LOG_DELETION:
+		printf("log{%s(%" PRIu64 ") delete", log->refname,
+		       log->update_index);
+		break;
+	case REFTABLE_LOG_UPDATE:
+		printf("log{%s(%" PRIu64 ") %s <%s> %" PRIu64 " %04d\n",
+		       log->refname, log->update_index, log->value.update.name,
+		       log->value.update.email, log->value.update.time,
+		       log->value.update.tz_offset);
+		hex_format(hex, log->value.update.old_hash, hash_size(hash_id));
+		printf("%s => ", hex);
+		hex_format(hex, log->value.update.new_hash, hash_size(hash_id));
+		printf("%s\n\n%s\n}\n", hex, log->value.update.message);
+		break;
+	}
+}
+
+static void reftable_log_record_key(const void *r, struct strbuf *dest)
+{
+	const struct reftable_log_record *rec =
+		(const struct reftable_log_record *)r;
+	int len = strlen(rec->refname);
+	uint8_t i64[8];
+	uint64_t ts = 0;
+	strbuf_reset(dest);
+	strbuf_add(dest, (uint8_t *)rec->refname, len + 1);
+
+	ts = (~ts) - rec->update_index;
+	put_be64(&i64[0], ts);
+	strbuf_add(dest, i64, sizeof(i64));
+}
+
+static void reftable_log_record_copy_from(void *rec, const void *src_rec,
+					  int hash_size)
+{
+	struct reftable_log_record *dst = rec;
+	const struct reftable_log_record *src =
+		(const struct reftable_log_record *)src_rec;
+
+	reftable_log_record_release(dst);
+	*dst = *src;
+	if (dst->refname) {
+		dst->refname = xstrdup(dst->refname);
+	}
+	switch (dst->value_type) {
+	case REFTABLE_LOG_DELETION:
+		break;
+	case REFTABLE_LOG_UPDATE:
+		if (dst->value.update.email) {
+			dst->value.update.email =
+				xstrdup(dst->value.update.email);
+		}
+		if (dst->value.update.name) {
+			dst->value.update.name =
+				xstrdup(dst->value.update.name);
+		}
+		if (dst->value.update.message) {
+			dst->value.update.message =
+				xstrdup(dst->value.update.message);
+		}
+
+		if (dst->value.update.new_hash) {
+			dst->value.update.new_hash = reftable_malloc(hash_size);
+			memcpy(dst->value.update.new_hash,
+			       src->value.update.new_hash, hash_size);
+		}
+		if (dst->value.update.old_hash) {
+			dst->value.update.old_hash = reftable_malloc(hash_size);
+			memcpy(dst->value.update.old_hash,
+			       src->value.update.old_hash, hash_size);
+		}
+		break;
+	}
+}
+
+static void reftable_log_record_release_void(void *rec)
+{
+	struct reftable_log_record *r = rec;
+	reftable_log_record_release(r);
+}
+
+void reftable_log_record_release(struct reftable_log_record *r)
+{
+	reftable_free(r->refname);
+	switch (r->value_type) {
+	case REFTABLE_LOG_DELETION:
+		break;
+	case REFTABLE_LOG_UPDATE:
+		reftable_free(r->value.update.new_hash);
+		reftable_free(r->value.update.old_hash);
+		reftable_free(r->value.update.name);
+		reftable_free(r->value.update.email);
+		reftable_free(r->value.update.message);
+		break;
+	}
+	memset(r, 0, sizeof(struct reftable_log_record));
+}
+
+static uint8_t reftable_log_record_val_type(const void *rec)
+{
+	const struct reftable_log_record *log =
+		(const struct reftable_log_record *)rec;
+
+	return reftable_log_record_is_deletion(log) ? 0 : 1;
+}
+
+static uint8_t zero[GIT_SHA256_RAWSZ] = { 0 };
+
+static int reftable_log_record_encode(const void *rec, struct string_view s,
+				      int hash_size)
+{
+	const struct reftable_log_record *r = rec;
+	struct string_view start = s;
+	int n = 0;
+	uint8_t *oldh = NULL;
+	uint8_t *newh = NULL;
+	if (reftable_log_record_is_deletion(r))
+		return 0;
+
+	oldh = r->value.update.old_hash;
+	newh = r->value.update.new_hash;
+	if (!oldh) {
+		oldh = zero;
+	}
+	if (!newh) {
+		newh = zero;
+	}
+
+	if (s.len < 2 * hash_size)
+		return -1;
+
+	memcpy(s.buf, oldh, hash_size);
+	memcpy(s.buf + hash_size, newh, hash_size);
+	string_view_consume(&s, 2 * hash_size);
+
+	n = encode_string(r->value.update.name ? r->value.update.name : "", s);
+	if (n < 0)
+		return -1;
+	string_view_consume(&s, n);
+
+	n = encode_string(r->value.update.email ? r->value.update.email : "",
+			  s);
+	if (n < 0)
+		return -1;
+	string_view_consume(&s, n);
+
+	n = put_var_int(&s, r->value.update.time);
+	if (n < 0)
+		return -1;
+	string_view_consume(&s, n);
+
+	if (s.len < 2)
+		return -1;
+
+	put_be16(s.buf, r->value.update.tz_offset);
+	string_view_consume(&s, 2);
+
+	n = encode_string(
+		r->value.update.message ? r->value.update.message : "", s);
+	if (n < 0)
+		return -1;
+	string_view_consume(&s, n);
+
+	return start.len - s.len;
+}
+
+static int reftable_log_record_decode(void *rec, struct strbuf key,
+				      uint8_t val_type, struct string_view in,
+				      int hash_size)
+{
+	struct string_view start = in;
+	struct reftable_log_record *r = rec;
+	uint64_t max = 0;
+	uint64_t ts = 0;
+	struct strbuf dest = STRBUF_INIT;
+	int n;
+
+	if (key.len <= 9 || key.buf[key.len - 9] != 0)
+		return REFTABLE_FORMAT_ERROR;
+
+	r->refname = reftable_realloc(r->refname, key.len - 8);
+	memcpy(r->refname, key.buf, key.len - 8);
+	ts = get_be64(key.buf + key.len - 8);
+
+	r->update_index = (~max) - ts;
+
+	if (val_type != r->value_type) {
+		switch (r->value_type) {
+		case REFTABLE_LOG_UPDATE:
+			FREE_AND_NULL(r->value.update.old_hash);
+			FREE_AND_NULL(r->value.update.new_hash);
+			FREE_AND_NULL(r->value.update.message);
+			FREE_AND_NULL(r->value.update.email);
+			FREE_AND_NULL(r->value.update.name);
+			break;
+		case REFTABLE_LOG_DELETION:
+			break;
+		}
+	}
+
+	r->value_type = val_type;
+	if (val_type == REFTABLE_LOG_DELETION)
+		return 0;
+
+	if (in.len < 2 * hash_size)
+		return REFTABLE_FORMAT_ERROR;
+
+	r->value.update.old_hash =
+		reftable_realloc(r->value.update.old_hash, hash_size);
+	r->value.update.new_hash =
+		reftable_realloc(r->value.update.new_hash, hash_size);
+
+	memcpy(r->value.update.old_hash, in.buf, hash_size);
+	memcpy(r->value.update.new_hash, in.buf + hash_size, hash_size);
+
+	string_view_consume(&in, 2 * hash_size);
+
+	n = decode_string(&dest, in);
+	if (n < 0)
+		goto done;
+	string_view_consume(&in, n);
+
+	r->value.update.name =
+		reftable_realloc(r->value.update.name, dest.len + 1);
+	memcpy(r->value.update.name, dest.buf, dest.len);
+	r->value.update.name[dest.len] = 0;
+
+	strbuf_reset(&dest);
+	n = decode_string(&dest, in);
+	if (n < 0)
+		goto done;
+	string_view_consume(&in, n);
+
+	r->value.update.email =
+		reftable_realloc(r->value.update.email, dest.len + 1);
+	memcpy(r->value.update.email, dest.buf, dest.len);
+	r->value.update.email[dest.len] = 0;
+
+	ts = 0;
+	n = get_var_int(&ts, &in);
+	if (n < 0)
+		goto done;
+	string_view_consume(&in, n);
+	r->value.update.time = ts;
+	if (in.len < 2)
+		goto done;
+
+	r->value.update.tz_offset = get_be16(in.buf);
+	string_view_consume(&in, 2);
+
+	strbuf_reset(&dest);
+	n = decode_string(&dest, in);
+	if (n < 0)
+		goto done;
+	string_view_consume(&in, n);
+
+	r->value.update.message =
+		reftable_realloc(r->value.update.message, dest.len + 1);
+	memcpy(r->value.update.message, dest.buf, dest.len);
+	r->value.update.message[dest.len] = 0;
+
+	strbuf_release(&dest);
+	return start.len - in.len;
+
+done:
+	strbuf_release(&dest);
+	return REFTABLE_FORMAT_ERROR;
+}
+
+static int null_streq(char *a, char *b)
+{
+	char *empty = "";
+	if (!a)
+		a = empty;
+
+	if (!b)
+		b = empty;
+
+	return 0 == strcmp(a, b);
+}
+
+static int zero_hash_eq(uint8_t *a, uint8_t *b, int sz)
+{
+	if (!a)
+		a = zero;
+
+	if (!b)
+		b = zero;
+
+	return !memcmp(a, b, sz);
+}
+
+int reftable_log_record_equal(struct reftable_log_record *a,
+			      struct reftable_log_record *b, int hash_size)
+{
+	if (!(null_streq(a->refname, b->refname) &&
+	      a->update_index == b->update_index &&
+	      a->value_type == b->value_type))
+		return 0;
+
+	switch (a->value_type) {
+	case REFTABLE_LOG_DELETION:
+		return 1;
+	case REFTABLE_LOG_UPDATE:
+		return null_streq(a->value.update.name, b->value.update.name) &&
+		       a->value.update.time == b->value.update.time &&
+		       a->value.update.tz_offset == b->value.update.tz_offset &&
+		       null_streq(a->value.update.email,
+				  b->value.update.email) &&
+		       null_streq(a->value.update.message,
+				  b->value.update.message) &&
+		       zero_hash_eq(a->value.update.old_hash,
+				    b->value.update.old_hash, hash_size) &&
+		       zero_hash_eq(a->value.update.new_hash,
+				    b->value.update.new_hash, hash_size);
+	}
+
+	abort();
+}
+
+static int reftable_log_record_is_deletion_void(const void *p)
+{
+	return reftable_log_record_is_deletion(
+		(const struct reftable_log_record *)p);
+}
+
+static struct reftable_record_vtable reftable_log_record_vtable = {
+	.key = &reftable_log_record_key,
+	.type = BLOCK_TYPE_LOG,
+	.copy_from = &reftable_log_record_copy_from,
+	.val_type = &reftable_log_record_val_type,
+	.encode = &reftable_log_record_encode,
+	.decode = &reftable_log_record_decode,
+	.release = &reftable_log_record_release_void,
+	.is_deletion = &reftable_log_record_is_deletion_void,
+};
+
+struct reftable_record reftable_new_record(uint8_t typ)
+{
+	struct reftable_record rec = { NULL };
+	switch (typ) {
+	case BLOCK_TYPE_REF: {
+		struct reftable_ref_record *r =
+			reftable_calloc(sizeof(struct reftable_ref_record));
+		reftable_record_from_ref(&rec, r);
+		return rec;
+	}
+
+	case BLOCK_TYPE_OBJ: {
+		struct reftable_obj_record *r =
+			reftable_calloc(sizeof(struct reftable_obj_record));
+		reftable_record_from_obj(&rec, r);
+		return rec;
+	}
+	case BLOCK_TYPE_LOG: {
+		struct reftable_log_record *r =
+			reftable_calloc(sizeof(struct reftable_log_record));
+		reftable_record_from_log(&rec, r);
+		return rec;
+	}
+	case BLOCK_TYPE_INDEX: {
+		struct reftable_index_record empty = { .last_key =
+							       STRBUF_INIT };
+		struct reftable_index_record *r =
+			reftable_calloc(sizeof(struct reftable_index_record));
+		*r = empty;
+		reftable_record_from_index(&rec, r);
+		return rec;
+	}
+	}
+	abort();
+	return rec;
+}
+
+/* clear out the record, yielding the reftable_record data that was
+ * encapsulated. */
+static void *reftable_record_yield(struct reftable_record *rec)
+{
+	void *p = rec->data;
+	rec->data = NULL;
+	return p;
+}
+
+void reftable_record_destroy(struct reftable_record *rec)
+{
+	reftable_record_release(rec);
+	reftable_free(reftable_record_yield(rec));
+}
+
+static void reftable_index_record_key(const void *r, struct strbuf *dest)
+{
+	const struct reftable_index_record *rec = r;
+	strbuf_reset(dest);
+	strbuf_addbuf(dest, &rec->last_key);
+}
+
+static void reftable_index_record_copy_from(void *rec, const void *src_rec,
+					    int hash_size)
+{
+	struct reftable_index_record *dst = rec;
+	const struct reftable_index_record *src = src_rec;
+
+	strbuf_reset(&dst->last_key);
+	strbuf_addbuf(&dst->last_key, &src->last_key);
+	dst->offset = src->offset;
+}
+
+static void reftable_index_record_release(void *rec)
+{
+	struct reftable_index_record *idx = rec;
+	strbuf_release(&idx->last_key);
+}
+
+static uint8_t reftable_index_record_val_type(const void *rec)
+{
+	return 0;
+}
+
+static int reftable_index_record_encode(const void *rec, struct string_view out,
+					int hash_size)
+{
+	const struct reftable_index_record *r =
+		(const struct reftable_index_record *)rec;
+	struct string_view start = out;
+
+	int n = put_var_int(&out, r->offset);
+	if (n < 0)
+		return n;
+
+	string_view_consume(&out, n);
+
+	return start.len - out.len;
+}
+
+static int reftable_index_record_decode(void *rec, struct strbuf key,
+					uint8_t val_type, struct string_view in,
+					int hash_size)
+{
+	struct string_view start = in;
+	struct reftable_index_record *r = rec;
+	int n = 0;
+
+	strbuf_reset(&r->last_key);
+	strbuf_addbuf(&r->last_key, &key);
+
+	n = get_var_int(&r->offset, &in);
+	if (n < 0)
+		return n;
+
+	string_view_consume(&in, n);
+	return start.len - in.len;
+}
+
+static struct reftable_record_vtable reftable_index_record_vtable = {
+	.key = &reftable_index_record_key,
+	.type = BLOCK_TYPE_INDEX,
+	.copy_from = &reftable_index_record_copy_from,
+	.val_type = &reftable_index_record_val_type,
+	.encode = &reftable_index_record_encode,
+	.decode = &reftable_index_record_decode,
+	.release = &reftable_index_record_release,
+	.is_deletion = &not_a_deletion,
+};
+
+void reftable_record_key(struct reftable_record *rec, struct strbuf *dest)
+{
+	rec->ops->key(rec->data, dest);
+}
+
+uint8_t reftable_record_type(struct reftable_record *rec)
+{
+	return rec->ops->type;
+}
+
+int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
+			   int hash_size)
+{
+	return rec->ops->encode(rec->data, dest, hash_size);
+}
+
+void reftable_record_copy_from(struct reftable_record *rec,
+			       struct reftable_record *src, int hash_size)
+{
+	assert(src->ops->type == rec->ops->type);
+
+	rec->ops->copy_from(rec->data, src->data, hash_size);
+}
+
+uint8_t reftable_record_val_type(struct reftable_record *rec)
+{
+	return rec->ops->val_type(rec->data);
+}
+
+int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
+			   uint8_t extra, struct string_view src, int hash_size)
+{
+	return rec->ops->decode(rec->data, key, extra, src, hash_size);
+}
+
+void reftable_record_release(struct reftable_record *rec)
+{
+	rec->ops->release(rec->data);
+}
+
+int reftable_record_is_deletion(struct reftable_record *rec)
+{
+	return rec->ops->is_deletion(rec->data);
+}
+
+void reftable_record_from_ref(struct reftable_record *rec,
+			      struct reftable_ref_record *ref_rec)
+{
+	assert(!rec->ops);
+	rec->data = ref_rec;
+	rec->ops = &reftable_ref_record_vtable;
+}
+
+void reftable_record_from_obj(struct reftable_record *rec,
+			      struct reftable_obj_record *obj_rec)
+{
+	assert(!rec->ops);
+	rec->data = obj_rec;
+	rec->ops = &reftable_obj_record_vtable;
+}
+
+void reftable_record_from_index(struct reftable_record *rec,
+				struct reftable_index_record *index_rec)
+{
+	assert(!rec->ops);
+	rec->data = index_rec;
+	rec->ops = &reftable_index_record_vtable;
+}
+
+void reftable_record_from_log(struct reftable_record *rec,
+			      struct reftable_log_record *log_rec)
+{
+	assert(!rec->ops);
+	rec->data = log_rec;
+	rec->ops = &reftable_log_record_vtable;
+}
+
+struct reftable_ref_record *reftable_record_as_ref(struct reftable_record *rec)
+{
+	assert(reftable_record_type(rec) == BLOCK_TYPE_REF);
+	return rec->data;
+}
+
+struct reftable_log_record *reftable_record_as_log(struct reftable_record *rec)
+{
+	assert(reftable_record_type(rec) == BLOCK_TYPE_LOG);
+	return rec->data;
+}
+
+static int hash_equal(uint8_t *a, uint8_t *b, int hash_size)
+{
+	if (a && b)
+		return !memcmp(a, b, hash_size);
+
+	return a == b;
+}
+
+int reftable_ref_record_equal(struct reftable_ref_record *a,
+			      struct reftable_ref_record *b, int hash_size)
+{
+	assert(hash_size > 0);
+	if (!(0 == strcmp(a->refname, b->refname) &&
+	      a->update_index == b->update_index &&
+	      a->value_type == b->value_type))
+		return 0;
+
+	switch (a->value_type) {
+	case REFTABLE_REF_SYMREF:
+		return !strcmp(a->value.symref, b->value.symref);
+	case REFTABLE_REF_VAL2:
+		return hash_equal(a->value.val2.value, b->value.val2.value,
+				  hash_size) &&
+		       hash_equal(a->value.val2.target_value,
+				  b->value.val2.target_value, hash_size);
+	case REFTABLE_REF_VAL1:
+		return hash_equal(a->value.val1, b->value.val1, hash_size);
+	case REFTABLE_REF_DELETION:
+		return 1;
+	default:
+		abort();
+	}
+}
+
+int reftable_ref_record_compare_name(const void *a, const void *b)
+{
+	return strcmp(((struct reftable_ref_record *)a)->refname,
+		      ((struct reftable_ref_record *)b)->refname);
+}
+
+int reftable_ref_record_is_deletion(const struct reftable_ref_record *ref)
+{
+	return ref->value_type == REFTABLE_REF_DELETION;
+}
+
+int reftable_log_record_compare_key(const void *a, const void *b)
+{
+	const struct reftable_log_record *la = a;
+	const struct reftable_log_record *lb = b;
+
+	int cmp = strcmp(la->refname, lb->refname);
+	if (cmp)
+		return cmp;
+	if (la->update_index > lb->update_index)
+		return -1;
+	return (la->update_index < lb->update_index) ? 1 : 0;
+}
+
+int reftable_log_record_is_deletion(const struct reftable_log_record *log)
+{
+	return (log->value_type == REFTABLE_LOG_DELETION);
+}
+
+void string_view_consume(struct string_view *s, int n)
+{
+	s->buf += n;
+	s->len -= n;
+}
diff --git a/reftable/record.h b/reftable/record.h
new file mode 100644
index 0000000..498e8c5
--- /dev/null
+++ b/reftable/record.h
@@ -0,0 +1,139 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef RECORD_H
+#define RECORD_H
+
+#include "system.h"
+
+#include <stdint.h>
+
+#include "reftable-record.h"
+
+/*
+ * A substring of existing string data. This structure takes no responsibility
+ * for the lifetime of the data it points to.
+ */
+struct string_view {
+	uint8_t *buf;
+	size_t len;
+};
+
+/* Advance `s.buf` by `n`, and decrease length. */
+void string_view_consume(struct string_view *s, int n);
+
+/* utilities for de/encoding varints */
+
+int get_var_int(uint64_t *dest, struct string_view *in);
+int put_var_int(struct string_view *dest, uint64_t val);
+
+/* Methods for records. */
+struct reftable_record_vtable {
+	/* encode the key of to a uint8_t strbuf. */
+	void (*key)(const void *rec, struct strbuf *dest);
+
+	/* The record type of ('r' for ref). */
+	uint8_t type;
+
+	void (*copy_from)(void *dest, const void *src, int hash_size);
+
+	/* a value of [0..7], indicating record subvariants (eg. ref vs. symref
+	 * vs ref deletion) */
+	uint8_t (*val_type)(const void *rec);
+
+	/* encodes rec into dest, returning how much space was used. */
+	int (*encode)(const void *rec, struct string_view dest, int hash_size);
+
+	/* decode data from `src` into the record. */
+	int (*decode)(void *rec, struct strbuf key, uint8_t extra,
+		      struct string_view src, int hash_size);
+
+	/* deallocate and null the record. */
+	void (*release)(void *rec);
+
+	/* is this a tombstone? */
+	int (*is_deletion)(const void *rec);
+};
+
+/* record is a generic wrapper for different types of records. */
+struct reftable_record {
+	void *data;
+	struct reftable_record_vtable *ops;
+};
+
+/* returns true for recognized block types. Block start with the block type. */
+int reftable_is_block_type(uint8_t typ);
+
+/* creates a malloced record of the given type. Dispose with record_destroy */
+struct reftable_record reftable_new_record(uint8_t typ);
+
+/* Encode `key` into `dest`. Sets `is_restart` to indicate a restart. Returns
+ * number of bytes written. */
+int reftable_encode_key(int *is_restart, struct string_view dest,
+			struct strbuf prev_key, struct strbuf key,
+			uint8_t extra);
+
+/* Decode into `key` and `extra` from `in` */
+int reftable_decode_key(struct strbuf *key, uint8_t *extra,
+			struct strbuf last_key, struct string_view in);
+
+/* reftable_index_record are used internally to speed up lookups. */
+struct reftable_index_record {
+	uint64_t offset; /* Offset of block */
+	struct strbuf last_key; /* Last key of the block. */
+};
+
+/* reftable_obj_record stores an object ID => ref mapping. */
+struct reftable_obj_record {
+	uint8_t *hash_prefix; /* leading bytes of the object ID */
+	int hash_prefix_len; /* number of leading bytes. Constant
+			      * across a single table. */
+	uint64_t *offsets; /* a vector of file offsets. */
+	int offset_len;
+};
+
+/* see struct record_vtable */
+
+void reftable_record_key(struct reftable_record *rec, struct strbuf *dest);
+uint8_t reftable_record_type(struct reftable_record *rec);
+void reftable_record_copy_from(struct reftable_record *rec,
+			       struct reftable_record *src, int hash_size);
+uint8_t reftable_record_val_type(struct reftable_record *rec);
+int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
+			   int hash_size);
+int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
+			   uint8_t extra, struct string_view src,
+			   int hash_size);
+int reftable_record_is_deletion(struct reftable_record *rec);
+
+/* zeroes out the embedded record */
+void reftable_record_release(struct reftable_record *rec);
+
+/* clear and deallocate embedded record, and zero `rec`. */
+void reftable_record_destroy(struct reftable_record *rec);
+
+/* initialize generic records from concrete records. The generic record should
+ * be zeroed out. */
+void reftable_record_from_obj(struct reftable_record *rec,
+			      struct reftable_obj_record *objrec);
+void reftable_record_from_index(struct reftable_record *rec,
+				struct reftable_index_record *idxrec);
+void reftable_record_from_ref(struct reftable_record *rec,
+			      struct reftable_ref_record *refrec);
+void reftable_record_from_log(struct reftable_record *rec,
+			      struct reftable_log_record *logrec);
+struct reftable_ref_record *reftable_record_as_ref(struct reftable_record *ref);
+struct reftable_log_record *reftable_record_as_log(struct reftable_record *ref);
+
+/* for qsort. */
+int reftable_ref_record_compare_name(const void *a, const void *b);
+
+/* for qsort. */
+int reftable_log_record_compare_key(const void *a, const void *b);
+
+#endif
diff --git a/reftable/record_test.c b/reftable/record_test.c
new file mode 100644
index 0000000..f4ad7ca
--- /dev/null
+++ b/reftable/record_test.c
@@ -0,0 +1,412 @@
+/*
+  Copyright 2020 Google LLC
+
+  Use of this source code is governed by a BSD-style
+  license that can be found in the LICENSE file or at
+  https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "record.h"
+
+#include "system.h"
+#include "basics.h"
+#include "constants.h"
+#include "test_framework.h"
+#include "reftable-tests.h"
+
+static void test_copy(struct reftable_record *rec)
+{
+	struct reftable_record copy =
+		reftable_new_record(reftable_record_type(rec));
+	reftable_record_copy_from(&copy, rec, GIT_SHA1_RAWSZ);
+	/* do it twice to catch memory leaks */
+	reftable_record_copy_from(&copy, rec, GIT_SHA1_RAWSZ);
+	switch (reftable_record_type(&copy)) {
+	case BLOCK_TYPE_REF:
+		EXPECT(reftable_ref_record_equal(reftable_record_as_ref(&copy),
+						 reftable_record_as_ref(rec),
+						 GIT_SHA1_RAWSZ));
+		break;
+	case BLOCK_TYPE_LOG:
+		EXPECT(reftable_log_record_equal(reftable_record_as_log(&copy),
+						 reftable_record_as_log(rec),
+						 GIT_SHA1_RAWSZ));
+		break;
+	}
+	reftable_record_destroy(&copy);
+}
+
+static void test_varint_roundtrip(void)
+{
+	uint64_t inputs[] = { 0,
+			      1,
+			      27,
+			      127,
+			      128,
+			      257,
+			      4096,
+			      ((uint64_t)1 << 63),
+			      ((uint64_t)1 << 63) + ((uint64_t)1 << 63) - 1 };
+	int i = 0;
+	for (i = 0; i < ARRAY_SIZE(inputs); i++) {
+		uint8_t dest[10];
+
+		struct string_view out = {
+			.buf = dest,
+			.len = sizeof(dest),
+		};
+		uint64_t in = inputs[i];
+		int n = put_var_int(&out, in);
+		uint64_t got = 0;
+
+		EXPECT(n > 0);
+		out.len = n;
+		n = get_var_int(&got, &out);
+		EXPECT(n > 0);
+
+		EXPECT(got == in);
+	}
+}
+
+static void test_common_prefix(void)
+{
+	struct {
+		const char *a, *b;
+		int want;
+	} cases[] = {
+		{ "abc", "ab", 2 },
+		{ "", "abc", 0 },
+		{ "abc", "abd", 2 },
+		{ "abc", "pqr", 0 },
+	};
+
+	int i = 0;
+	for (i = 0; i < ARRAY_SIZE(cases); i++) {
+		struct strbuf a = STRBUF_INIT;
+		struct strbuf b = STRBUF_INIT;
+		strbuf_addstr(&a, cases[i].a);
+		strbuf_addstr(&b, cases[i].b);
+		EXPECT(common_prefix_size(&a, &b) == cases[i].want);
+
+		strbuf_release(&a);
+		strbuf_release(&b);
+	}
+}
+
+static void set_hash(uint8_t *h, int j)
+{
+	int i = 0;
+	for (i = 0; i < hash_size(GIT_SHA1_FORMAT_ID); i++) {
+		h[i] = (j >> i) & 0xff;
+	}
+}
+
+static void test_reftable_ref_record_roundtrip(void)
+{
+	int i = 0;
+
+	for (i = REFTABLE_REF_DELETION; i < REFTABLE_NR_REF_VALUETYPES; i++) {
+		struct reftable_ref_record in = { NULL };
+		struct reftable_ref_record out = { NULL };
+		struct reftable_record rec_out = { NULL };
+		struct strbuf key = STRBUF_INIT;
+		struct reftable_record rec = { NULL };
+		uint8_t buffer[1024] = { 0 };
+		struct string_view dest = {
+			.buf = buffer,
+			.len = sizeof(buffer),
+		};
+
+		int n, m;
+
+		in.value_type = i;
+		switch (i) {
+		case REFTABLE_REF_DELETION:
+			break;
+		case REFTABLE_REF_VAL1:
+			in.value.val1 = reftable_malloc(GIT_SHA1_RAWSZ);
+			set_hash(in.value.val1, 1);
+			break;
+		case REFTABLE_REF_VAL2:
+			in.value.val2.value = reftable_malloc(GIT_SHA1_RAWSZ);
+			set_hash(in.value.val2.value, 1);
+			in.value.val2.target_value =
+				reftable_malloc(GIT_SHA1_RAWSZ);
+			set_hash(in.value.val2.target_value, 2);
+			break;
+		case REFTABLE_REF_SYMREF:
+			in.value.symref = xstrdup("target");
+			break;
+		}
+		in.refname = xstrdup("refs/heads/master");
+
+		reftable_record_from_ref(&rec, &in);
+		test_copy(&rec);
+
+		EXPECT(reftable_record_val_type(&rec) == i);
+
+		reftable_record_key(&rec, &key);
+		n = reftable_record_encode(&rec, dest, GIT_SHA1_RAWSZ);
+		EXPECT(n > 0);
+
+		/* decode into a non-zero reftable_record to test for leaks. */
+
+		reftable_record_from_ref(&rec_out, &out);
+		m = reftable_record_decode(&rec_out, key, i, dest,
+					   GIT_SHA1_RAWSZ);
+		EXPECT(n == m);
+
+		EXPECT(reftable_ref_record_equal(&in, &out, GIT_SHA1_RAWSZ));
+		reftable_record_release(&rec_out);
+
+		strbuf_release(&key);
+		reftable_ref_record_release(&in);
+	}
+}
+
+static void test_reftable_log_record_equal(void)
+{
+	struct reftable_log_record in[2] = {
+		{
+			.refname = xstrdup("refs/heads/master"),
+			.update_index = 42,
+		},
+		{
+			.refname = xstrdup("refs/heads/master"),
+			.update_index = 22,
+		}
+	};
+
+	EXPECT(!reftable_log_record_equal(&in[0], &in[1], GIT_SHA1_RAWSZ));
+	in[1].update_index = in[0].update_index;
+	EXPECT(reftable_log_record_equal(&in[0], &in[1], GIT_SHA1_RAWSZ));
+	reftable_log_record_release(&in[0]);
+	reftable_log_record_release(&in[1]);
+}
+
+static void test_reftable_log_record_roundtrip(void)
+{
+	int i;
+	struct reftable_log_record in[2] = {
+		{
+			.refname = xstrdup("refs/heads/master"),
+			.update_index = 42,
+			.value_type = REFTABLE_LOG_UPDATE,
+			.value = {
+				.update = {
+					.old_hash = reftable_malloc(GIT_SHA1_RAWSZ),
+					.new_hash = reftable_malloc(GIT_SHA1_RAWSZ),
+					.name = xstrdup("han-wen"),
+					.email = xstrdup("hanwen@google.com"),
+					.message = xstrdup("test"),
+					.time = 1577123507,
+					.tz_offset = 100,
+				},
+			}
+		},
+		{
+			.refname = xstrdup("refs/heads/master"),
+			.update_index = 22,
+			.value_type = REFTABLE_LOG_DELETION,
+		}
+	};
+	set_test_hash(in[0].value.update.new_hash, 1);
+	set_test_hash(in[0].value.update.old_hash, 2);
+	for (i = 0; i < ARRAY_SIZE(in); i++) {
+		struct reftable_record rec = { NULL };
+		struct strbuf key = STRBUF_INIT;
+		uint8_t buffer[1024] = { 0 };
+		struct string_view dest = {
+			.buf = buffer,
+			.len = sizeof(buffer),
+		};
+		/* populate out, to check for leaks. */
+		struct reftable_log_record out = {
+			.refname = xstrdup("old name"),
+			.value_type = REFTABLE_LOG_UPDATE,
+			.value = {
+				.update = {
+					.new_hash = reftable_calloc(GIT_SHA1_RAWSZ),
+					.old_hash = reftable_calloc(GIT_SHA1_RAWSZ),
+					.name = xstrdup("old name"),
+					.email = xstrdup("old@email"),
+					.message = xstrdup("old message"),
+				},
+			},
+		};
+		struct reftable_record rec_out = { NULL };
+		int n, m, valtype;
+
+		reftable_record_from_log(&rec, &in[i]);
+
+		test_copy(&rec);
+
+		reftable_record_key(&rec, &key);
+
+		n = reftable_record_encode(&rec, dest, GIT_SHA1_RAWSZ);
+		EXPECT(n >= 0);
+		reftable_record_from_log(&rec_out, &out);
+		valtype = reftable_record_val_type(&rec);
+		m = reftable_record_decode(&rec_out, key, valtype, dest,
+					   GIT_SHA1_RAWSZ);
+		EXPECT(n == m);
+
+		EXPECT(reftable_log_record_equal(&in[i], &out, GIT_SHA1_RAWSZ));
+		reftable_log_record_release(&in[i]);
+		strbuf_release(&key);
+		reftable_record_release(&rec_out);
+	}
+}
+
+static void test_u24_roundtrip(void)
+{
+	uint32_t in = 0x112233;
+	uint8_t dest[3];
+	uint32_t out;
+	put_be24(dest, in);
+	out = get_be24(dest);
+	EXPECT(in == out);
+}
+
+static void test_key_roundtrip(void)
+{
+	uint8_t buffer[1024] = { 0 };
+	struct string_view dest = {
+		.buf = buffer,
+		.len = sizeof(buffer),
+	};
+	struct strbuf last_key = STRBUF_INIT;
+	struct strbuf key = STRBUF_INIT;
+	struct strbuf roundtrip = STRBUF_INIT;
+	int restart;
+	uint8_t extra;
+	int n, m;
+	uint8_t rt_extra;
+
+	strbuf_addstr(&last_key, "refs/heads/master");
+	strbuf_addstr(&key, "refs/tags/bla");
+	extra = 6;
+	n = reftable_encode_key(&restart, dest, last_key, key, extra);
+	EXPECT(!restart);
+	EXPECT(n > 0);
+
+	m = reftable_decode_key(&roundtrip, &rt_extra, last_key, dest);
+	EXPECT(n == m);
+	EXPECT(0 == strbuf_cmp(&key, &roundtrip));
+	EXPECT(rt_extra == extra);
+
+	strbuf_release(&last_key);
+	strbuf_release(&key);
+	strbuf_release(&roundtrip);
+}
+
+static void test_reftable_obj_record_roundtrip(void)
+{
+	uint8_t testHash1[GIT_SHA1_RAWSZ] = { 1, 2, 3, 4, 0 };
+	uint64_t till9[] = { 1, 2, 3, 4, 500, 600, 700, 800, 9000 };
+	struct reftable_obj_record recs[3] = { {
+						       .hash_prefix = testHash1,
+						       .hash_prefix_len = 5,
+						       .offsets = till9,
+						       .offset_len = 3,
+					       },
+					       {
+						       .hash_prefix = testHash1,
+						       .hash_prefix_len = 5,
+						       .offsets = till9,
+						       .offset_len = 9,
+					       },
+					       {
+						       .hash_prefix = testHash1,
+						       .hash_prefix_len = 5,
+					       } };
+	int i = 0;
+	for (i = 0; i < ARRAY_SIZE(recs); i++) {
+		struct reftable_obj_record in = recs[i];
+		uint8_t buffer[1024] = { 0 };
+		struct string_view dest = {
+			.buf = buffer,
+			.len = sizeof(buffer),
+		};
+		struct reftable_record rec = { NULL };
+		struct strbuf key = STRBUF_INIT;
+		struct reftable_obj_record out = { NULL };
+		struct reftable_record rec_out = { NULL };
+		int n, m;
+		uint8_t extra;
+
+		reftable_record_from_obj(&rec, &in);
+		test_copy(&rec);
+		reftable_record_key(&rec, &key);
+		n = reftable_record_encode(&rec, dest, GIT_SHA1_RAWSZ);
+		EXPECT(n > 0);
+		extra = reftable_record_val_type(&rec);
+		reftable_record_from_obj(&rec_out, &out);
+		m = reftable_record_decode(&rec_out, key, extra, dest,
+					   GIT_SHA1_RAWSZ);
+		EXPECT(n == m);
+
+		EXPECT(in.hash_prefix_len == out.hash_prefix_len);
+		EXPECT(in.offset_len == out.offset_len);
+
+		EXPECT(!memcmp(in.hash_prefix, out.hash_prefix,
+			       in.hash_prefix_len));
+		EXPECT(0 == memcmp(in.offsets, out.offsets,
+				   sizeof(uint64_t) * in.offset_len));
+		strbuf_release(&key);
+		reftable_record_release(&rec_out);
+	}
+}
+
+static void test_reftable_index_record_roundtrip(void)
+{
+	struct reftable_index_record in = {
+		.offset = 42,
+		.last_key = STRBUF_INIT,
+	};
+	uint8_t buffer[1024] = { 0 };
+	struct string_view dest = {
+		.buf = buffer,
+		.len = sizeof(buffer),
+	};
+	struct strbuf key = STRBUF_INIT;
+	struct reftable_record rec = { NULL };
+	struct reftable_index_record out = { .last_key = STRBUF_INIT };
+	struct reftable_record out_rec = { NULL };
+	int n, m;
+	uint8_t extra;
+
+	strbuf_addstr(&in.last_key, "refs/heads/master");
+	reftable_record_from_index(&rec, &in);
+	reftable_record_key(&rec, &key);
+	test_copy(&rec);
+
+	EXPECT(0 == strbuf_cmp(&key, &in.last_key));
+	n = reftable_record_encode(&rec, dest, GIT_SHA1_RAWSZ);
+	EXPECT(n > 0);
+
+	extra = reftable_record_val_type(&rec);
+	reftable_record_from_index(&out_rec, &out);
+	m = reftable_record_decode(&out_rec, key, extra, dest, GIT_SHA1_RAWSZ);
+	EXPECT(m == n);
+
+	EXPECT(in.offset == out.offset);
+
+	reftable_record_release(&out_rec);
+	strbuf_release(&key);
+	strbuf_release(&in.last_key);
+}
+
+int record_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_reftable_log_record_equal);
+	RUN_TEST(test_reftable_log_record_roundtrip);
+	RUN_TEST(test_reftable_ref_record_roundtrip);
+	RUN_TEST(test_varint_roundtrip);
+	RUN_TEST(test_key_roundtrip);
+	RUN_TEST(test_common_prefix);
+	RUN_TEST(test_reftable_obj_record_roundtrip);
+	RUN_TEST(test_reftable_index_record_roundtrip);
+	RUN_TEST(test_u24_roundtrip);
+	return 0;
+}
diff --git a/reftable/refname.c b/reftable/refname.c
new file mode 100644
index 0000000..9573496
--- /dev/null
+++ b/reftable/refname.c
@@ -0,0 +1,209 @@
+/*
+  Copyright 2020 Google LLC
+
+  Use of this source code is governed by a BSD-style
+  license that can be found in the LICENSE file or at
+  https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "system.h"
+#include "reftable-error.h"
+#include "basics.h"
+#include "refname.h"
+#include "reftable-iterator.h"
+
+struct find_arg {
+	char **names;
+	const char *want;
+};
+
+static int find_name(size_t k, void *arg)
+{
+	struct find_arg *f_arg = arg;
+	return strcmp(f_arg->names[k], f_arg->want) >= 0;
+}
+
+static int modification_has_ref(struct modification *mod, const char *name)
+{
+	struct reftable_ref_record ref = { NULL };
+	int err = 0;
+
+	if (mod->add_len > 0) {
+		struct find_arg arg = {
+			.names = mod->add,
+			.want = name,
+		};
+		int idx = binsearch(mod->add_len, find_name, &arg);
+		if (idx < mod->add_len && !strcmp(mod->add[idx], name)) {
+			return 0;
+		}
+	}
+
+	if (mod->del_len > 0) {
+		struct find_arg arg = {
+			.names = mod->del,
+			.want = name,
+		};
+		int idx = binsearch(mod->del_len, find_name, &arg);
+		if (idx < mod->del_len && !strcmp(mod->del[idx], name)) {
+			return 1;
+		}
+	}
+
+	err = reftable_table_read_ref(&mod->tab, name, &ref);
+	reftable_ref_record_release(&ref);
+	return err;
+}
+
+static void modification_release(struct modification *mod)
+{
+	/* don't delete the strings themselves; they're owned by ref records.
+	 */
+	FREE_AND_NULL(mod->add);
+	FREE_AND_NULL(mod->del);
+	mod->add_len = 0;
+	mod->del_len = 0;
+}
+
+static int modification_has_ref_with_prefix(struct modification *mod,
+					    const char *prefix)
+{
+	struct reftable_iterator it = { NULL };
+	struct reftable_ref_record ref = { NULL };
+	int err = 0;
+
+	if (mod->add_len > 0) {
+		struct find_arg arg = {
+			.names = mod->add,
+			.want = prefix,
+		};
+		int idx = binsearch(mod->add_len, find_name, &arg);
+		if (idx < mod->add_len &&
+		    !strncmp(prefix, mod->add[idx], strlen(prefix)))
+			goto done;
+	}
+	err = reftable_table_seek_ref(&mod->tab, &it, prefix);
+	if (err)
+		goto done;
+
+	while (1) {
+		err = reftable_iterator_next_ref(&it, &ref);
+		if (err)
+			goto done;
+
+		if (mod->del_len > 0) {
+			struct find_arg arg = {
+				.names = mod->del,
+				.want = ref.refname,
+			};
+			int idx = binsearch(mod->del_len, find_name, &arg);
+			if (idx < mod->del_len &&
+			    !strcmp(ref.refname, mod->del[idx])) {
+				continue;
+			}
+		}
+
+		if (strncmp(ref.refname, prefix, strlen(prefix))) {
+			err = 1;
+			goto done;
+		}
+		err = 0;
+		goto done;
+	}
+
+done:
+	reftable_ref_record_release(&ref);
+	reftable_iterator_destroy(&it);
+	return err;
+}
+
+static int validate_refname(const char *name)
+{
+	while (1) {
+		char *next = strchr(name, '/');
+		if (!*name) {
+			return REFTABLE_REFNAME_ERROR;
+		}
+		if (!next) {
+			return 0;
+		}
+		if (next - name == 0 || (next - name == 1 && *name == '.') ||
+		    (next - name == 2 && name[0] == '.' && name[1] == '.'))
+			return REFTABLE_REFNAME_ERROR;
+		name = next + 1;
+	}
+	return 0;
+}
+
+int validate_ref_record_addition(struct reftable_table tab,
+				 struct reftable_ref_record *recs, size_t sz)
+{
+	struct modification mod = {
+		.tab = tab,
+		.add = reftable_calloc(sizeof(char *) * sz),
+		.del = reftable_calloc(sizeof(char *) * sz),
+	};
+	int i = 0;
+	int err = 0;
+	for (; i < sz; i++) {
+		if (reftable_ref_record_is_deletion(&recs[i])) {
+			mod.del[mod.del_len++] = recs[i].refname;
+		} else {
+			mod.add[mod.add_len++] = recs[i].refname;
+		}
+	}
+
+	err = modification_validate(&mod);
+	modification_release(&mod);
+	return err;
+}
+
+static void strbuf_trim_component(struct strbuf *sl)
+{
+	while (sl->len > 0) {
+		int is_slash = (sl->buf[sl->len - 1] == '/');
+		strbuf_setlen(sl, sl->len - 1);
+		if (is_slash)
+			break;
+	}
+}
+
+int modification_validate(struct modification *mod)
+{
+	struct strbuf slashed = STRBUF_INIT;
+	int err = 0;
+	int i = 0;
+	for (; i < mod->add_len; i++) {
+		err = validate_refname(mod->add[i]);
+		if (err)
+			goto done;
+		strbuf_reset(&slashed);
+		strbuf_addstr(&slashed, mod->add[i]);
+		strbuf_addstr(&slashed, "/");
+
+		err = modification_has_ref_with_prefix(mod, slashed.buf);
+		if (err == 0) {
+			err = REFTABLE_NAME_CONFLICT;
+			goto done;
+		}
+		if (err < 0)
+			goto done;
+
+		strbuf_reset(&slashed);
+		strbuf_addstr(&slashed, mod->add[i]);
+		while (slashed.len) {
+			strbuf_trim_component(&slashed);
+			err = modification_has_ref(mod, slashed.buf);
+			if (err == 0) {
+				err = REFTABLE_NAME_CONFLICT;
+				goto done;
+			}
+			if (err < 0)
+				goto done;
+		}
+	}
+	err = 0;
+done:
+	strbuf_release(&slashed);
+	return err;
+}
diff --git a/reftable/refname.h b/reftable/refname.h
new file mode 100644
index 0000000..a24b40f
--- /dev/null
+++ b/reftable/refname.h
@@ -0,0 +1,29 @@
+/*
+  Copyright 2020 Google LLC
+
+  Use of this source code is governed by a BSD-style
+  license that can be found in the LICENSE file or at
+  https://developers.google.com/open-source/licenses/bsd
+*/
+#ifndef REFNAME_H
+#define REFNAME_H
+
+#include "reftable-record.h"
+#include "reftable-generic.h"
+
+struct modification {
+	struct reftable_table tab;
+
+	char **add;
+	size_t add_len;
+
+	char **del;
+	size_t del_len;
+};
+
+int validate_ref_record_addition(struct reftable_table tab,
+				 struct reftable_ref_record *recs, size_t sz);
+
+int modification_validate(struct modification *mod);
+
+#endif
diff --git a/reftable/refname_test.c b/reftable/refname_test.c
new file mode 100644
index 0000000..8645cd9
--- /dev/null
+++ b/reftable/refname_test.c
@@ -0,0 +1,102 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "basics.h"
+#include "block.h"
+#include "blocksource.h"
+#include "constants.h"
+#include "reader.h"
+#include "record.h"
+#include "refname.h"
+#include "reftable-error.h"
+#include "reftable-writer.h"
+#include "system.h"
+
+#include "test_framework.h"
+#include "reftable-tests.h"
+
+struct testcase {
+	char *add;
+	char *del;
+	int error_code;
+};
+
+static void test_conflict(void)
+{
+	struct reftable_write_options opts = { 0 };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+	struct reftable_ref_record rec = {
+		.refname = "a/b",
+		.value_type = REFTABLE_REF_SYMREF,
+		.value.symref = "destination", /* make sure it's not a symref.
+						*/
+		.update_index = 1,
+	};
+	int err;
+	int i;
+	struct reftable_block_source source = { NULL };
+	struct reftable_reader *rd = NULL;
+	struct reftable_table tab = { NULL };
+	struct testcase cases[] = {
+		{ "a/b/c", NULL, REFTABLE_NAME_CONFLICT },
+		{ "b", NULL, 0 },
+		{ "a", NULL, REFTABLE_NAME_CONFLICT },
+		{ "a", "a/b", 0 },
+
+		{ "p/", NULL, REFTABLE_REFNAME_ERROR },
+		{ "p//q", NULL, REFTABLE_REFNAME_ERROR },
+		{ "p/./q", NULL, REFTABLE_REFNAME_ERROR },
+		{ "p/../q", NULL, REFTABLE_REFNAME_ERROR },
+
+		{ "a/b/c", "a/b", 0 },
+		{ NULL, "a//b", 0 },
+	};
+	reftable_writer_set_limits(w, 1, 1);
+
+	err = reftable_writer_add_ref(w, &rec);
+	EXPECT_ERR(err);
+
+	err = reftable_writer_close(w);
+	EXPECT_ERR(err);
+	reftable_writer_free(w);
+
+	block_source_from_strbuf(&source, &buf);
+	err = reftable_new_reader(&rd, &source, "filename");
+	EXPECT_ERR(err);
+
+	reftable_table_from_reader(&tab, rd);
+
+	for (i = 0; i < ARRAY_SIZE(cases); i++) {
+		struct modification mod = {
+			.tab = tab,
+		};
+
+		if (cases[i].add) {
+			mod.add = &cases[i].add;
+			mod.add_len = 1;
+		}
+		if (cases[i].del) {
+			mod.del = &cases[i].del;
+			mod.del_len = 1;
+		}
+
+		err = modification_validate(&mod);
+		EXPECT(err == cases[i].error_code);
+	}
+
+	reftable_reader_free(rd);
+	strbuf_release(&buf);
+}
+
+int refname_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_conflict);
+	return 0;
+}
diff --git a/reftable/reftable-blocksource.h b/reftable/reftable-blocksource.h
new file mode 100644
index 0000000..5aa3990
--- /dev/null
+++ b/reftable/reftable-blocksource.h
@@ -0,0 +1,49 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_BLOCKSOURCE_H
+#define REFTABLE_BLOCKSOURCE_H
+
+#include <stdint.h>
+
+/* block_source is a generic wrapper for a seekable readable file.
+ */
+struct reftable_block_source {
+	struct reftable_block_source_vtable *ops;
+	void *arg;
+};
+
+/* a contiguous segment of bytes. It keeps track of its generating block_source
+ * so it can return itself into the pool. */
+struct reftable_block {
+	uint8_t *data;
+	int len;
+	struct reftable_block_source source;
+};
+
+/* block_source_vtable are the operations that make up block_source */
+struct reftable_block_source_vtable {
+	/* returns the size of a block source */
+	uint64_t (*size)(void *source);
+
+	/* reads a segment from the block source. It is an error to read
+	   beyond the end of the block */
+	int (*read_block)(void *source, struct reftable_block *dest,
+			  uint64_t off, uint32_t size);
+	/* mark the block as read; may return the data back to malloc */
+	void (*return_block)(void *source, struct reftable_block *blockp);
+
+	/* release all resources associated with the block source */
+	void (*close)(void *source);
+};
+
+/* opens a file on the file system as a block_source */
+int reftable_block_source_from_file(struct reftable_block_source *block_src,
+				    const char *name);
+
+#endif
diff --git a/reftable/reftable-error.h b/reftable/reftable-error.h
new file mode 100644
index 0000000..4c457aa
--- /dev/null
+++ b/reftable/reftable-error.h
@@ -0,0 +1,66 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_ERROR_H
+#define REFTABLE_ERROR_H
+
+/*
+ * Errors in reftable calls are signaled with negative integer return values. 0
+ * means success.
+ */
+enum reftable_error {
+	/* Unexpected file system behavior */
+	REFTABLE_IO_ERROR = -2,
+
+	/* Format inconsistency on reading data */
+	REFTABLE_FORMAT_ERROR = -3,
+
+	/* File does not exist. Returned from block_source_from_file(), because
+	 * it needs special handling in stack.
+	 */
+	REFTABLE_NOT_EXIST_ERROR = -4,
+
+	/* Trying to write out-of-date data. */
+	REFTABLE_LOCK_ERROR = -5,
+
+	/* Misuse of the API:
+	 *  - on writing a record with NULL refname.
+	 *  - on writing a reftable_ref_record outside the table limits
+	 *  - on writing a ref or log record before the stack's
+	 * next_update_inde*x
+	 *  - on writing a log record with multiline message with
+	 *  exact_log_message unset
+	 *  - on reading a reftable_ref_record from log iterator, or vice versa.
+	 *
+	 * When a call misuses the API, the internal state of the library is
+	 * kept unchanged.
+	 */
+	REFTABLE_API_ERROR = -6,
+
+	/* Decompression error */
+	REFTABLE_ZLIB_ERROR = -7,
+
+	/* Wrote a table without blocks. */
+	REFTABLE_EMPTY_TABLE_ERROR = -8,
+
+	/* Dir/file conflict. */
+	REFTABLE_NAME_CONFLICT = -9,
+
+	/* Invalid ref name. */
+	REFTABLE_REFNAME_ERROR = -10,
+
+	/* Entry does not fit. This can happen when writing outsize reflog
+	   messages. */
+	REFTABLE_ENTRY_TOO_BIG_ERROR = -11,
+};
+
+/* convert the numeric error code to a string. The string should not be
+ * deallocated. */
+const char *reftable_error_str(int err);
+
+#endif
diff --git a/reftable/reftable-generic.h b/reftable/reftable-generic.h
new file mode 100644
index 0000000..d239751
--- /dev/null
+++ b/reftable/reftable-generic.h
@@ -0,0 +1,47 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_GENERIC_H
+#define REFTABLE_GENERIC_H
+
+#include "reftable-iterator.h"
+
+struct reftable_table_vtable;
+
+/*
+ * Provides a unified API for reading tables, either merged tables, or single
+ * readers. */
+struct reftable_table {
+	struct reftable_table_vtable *ops;
+	void *table_arg;
+};
+
+int reftable_table_seek_log(struct reftable_table *tab,
+			    struct reftable_iterator *it, const char *name);
+
+int reftable_table_seek_ref(struct reftable_table *tab,
+			    struct reftable_iterator *it, const char *name);
+
+/* returns the hash ID from a generic reftable_table */
+uint32_t reftable_table_hash_id(struct reftable_table *tab);
+
+/* returns the max update_index covered by this table. */
+uint64_t reftable_table_max_update_index(struct reftable_table *tab);
+
+/* returns the min update_index covered by this table. */
+uint64_t reftable_table_min_update_index(struct reftable_table *tab);
+
+/* convenience function to read a single ref. Returns < 0 for error, 0
+   for success, and 1 if ref not found. */
+int reftable_table_read_ref(struct reftable_table *tab, const char *name,
+			    struct reftable_ref_record *ref);
+
+/* dump table contents onto stdout for debugging */
+int reftable_table_print(struct reftable_table *tab);
+
+#endif
diff --git a/reftable/reftable-iterator.h b/reftable/reftable-iterator.h
new file mode 100644
index 0000000..d3eee7a
--- /dev/null
+++ b/reftable/reftable-iterator.h
@@ -0,0 +1,39 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_ITERATOR_H
+#define REFTABLE_ITERATOR_H
+
+#include "reftable-record.h"
+
+struct reftable_iterator_vtable;
+
+/* iterator is the generic interface for walking over data stored in a
+ * reftable.
+ */
+struct reftable_iterator {
+	struct reftable_iterator_vtable *ops;
+	void *iter_arg;
+};
+
+/* reads the next reftable_ref_record. Returns < 0 for error, 0 for OK and > 0:
+ * end of iteration.
+ */
+int reftable_iterator_next_ref(struct reftable_iterator *it,
+			       struct reftable_ref_record *ref);
+
+/* reads the next reftable_log_record. Returns < 0 for error, 0 for OK and > 0:
+ * end of iteration.
+ */
+int reftable_iterator_next_log(struct reftable_iterator *it,
+			       struct reftable_log_record *log);
+
+/* releases resources associated with an iterator. */
+void reftable_iterator_destroy(struct reftable_iterator *it);
+
+#endif
diff --git a/reftable/reftable-malloc.h b/reftable/reftable-malloc.h
new file mode 100644
index 0000000..5f2185f
--- /dev/null
+++ b/reftable/reftable-malloc.h
@@ -0,0 +1,18 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_H
+#define REFTABLE_H
+
+#include <stddef.h>
+
+/* Overrides the functions to use for memory management. */
+void reftable_set_alloc(void *(*malloc)(size_t),
+			void *(*realloc)(void *, size_t), void (*free)(void *));
+
+#endif
diff --git a/reftable/reftable-merged.h b/reftable/reftable-merged.h
new file mode 100644
index 0000000..1a6d169
--- /dev/null
+++ b/reftable/reftable-merged.h
@@ -0,0 +1,72 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_MERGED_H
+#define REFTABLE_MERGED_H
+
+#include "reftable-iterator.h"
+
+/*
+ * Merged tables
+ *
+ * A ref database kept in a sequence of table files. The merged_table presents a
+ * unified view to reading (seeking, iterating) a sequence of immutable tables.
+ *
+ * The merged tables are on purpose kept disconnected from their actual storage
+ * (eg. files on disk), because it is useful to merge tables aren't files. For
+ * example, the per-workspace and global ref namespace can be implemented as a
+ * merged table of two stacks of file-backed reftables.
+ */
+
+/* A merged table is implements seeking/iterating over a stack of tables. */
+struct reftable_merged_table;
+
+/* A generic reftable; see below. */
+struct reftable_table;
+
+/* reftable_new_merged_table creates a new merged table. It takes ownership of
+   the stack array.
+*/
+int reftable_new_merged_table(struct reftable_merged_table **dest,
+			      struct reftable_table *stack, int n,
+			      uint32_t hash_id);
+
+/* returns an iterator positioned just before 'name' */
+int reftable_merged_table_seek_ref(struct reftable_merged_table *mt,
+				   struct reftable_iterator *it,
+				   const char *name);
+
+/* returns an iterator for log entry, at given update_index */
+int reftable_merged_table_seek_log_at(struct reftable_merged_table *mt,
+				      struct reftable_iterator *it,
+				      const char *name, uint64_t update_index);
+
+/* like reftable_merged_table_seek_log_at but look for the newest entry. */
+int reftable_merged_table_seek_log(struct reftable_merged_table *mt,
+				   struct reftable_iterator *it,
+				   const char *name);
+
+/* returns the max update_index covered by this merged table. */
+uint64_t
+reftable_merged_table_max_update_index(struct reftable_merged_table *mt);
+
+/* returns the min update_index covered by this merged table. */
+uint64_t
+reftable_merged_table_min_update_index(struct reftable_merged_table *mt);
+
+/* releases memory for the merged_table */
+void reftable_merged_table_free(struct reftable_merged_table *m);
+
+/* return the hash ID of the merged table. */
+uint32_t reftable_merged_table_hash_id(struct reftable_merged_table *m);
+
+/* create a generic table from reftable_merged_table */
+void reftable_table_from_merged_table(struct reftable_table *tab,
+				      struct reftable_merged_table *table);
+
+#endif
diff --git a/reftable/reftable-reader.h b/reftable/reftable-reader.h
new file mode 100644
index 0000000..4a4bc2f
--- /dev/null
+++ b/reftable/reftable-reader.h
@@ -0,0 +1,101 @@
+/*
+  Copyright 2020 Google LLC
+
+  Use of this source code is governed by a BSD-style
+  license that can be found in the LICENSE file or at
+  https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_READER_H
+#define REFTABLE_READER_H
+
+#include "reftable-iterator.h"
+#include "reftable-blocksource.h"
+
+/*
+ * Reading single tables
+ *
+ * The follow routines are for reading single files. For an
+ * application-level interface, skip ahead to struct
+ * reftable_merged_table and struct reftable_stack.
+ */
+
+/* The reader struct is a handle to an open reftable file. */
+struct reftable_reader;
+
+/* Generic table. */
+struct reftable_table;
+
+/* reftable_new_reader opens a reftable for reading. If successful,
+ * returns 0 code and sets pp. The name is used for creating a
+ * stack. Typically, it is the basename of the file. The block source
+ * `src` is owned by the reader, and is closed on calling
+ * reftable_reader_destroy(). On error, the block source `src` is
+ * closed as well.
+ */
+int reftable_new_reader(struct reftable_reader **pp,
+			struct reftable_block_source *src, const char *name);
+
+/* reftable_reader_seek_ref returns an iterator where 'name' would be inserted
+   in the table.  To seek to the start of the table, use name = "".
+
+   example:
+
+   struct reftable_reader *r = NULL;
+   int err = reftable_new_reader(&r, &src, "filename");
+   if (err < 0) { ... }
+   struct reftable_iterator it  = {0};
+   err = reftable_reader_seek_ref(r, &it, "refs/heads/master");
+   if (err < 0) { ... }
+   struct reftable_ref_record ref  = {0};
+   while (1) {
+   err = reftable_iterator_next_ref(&it, &ref);
+   if (err > 0) {
+   break;
+   }
+   if (err < 0) {
+   ..error handling..
+   }
+   ..found..
+   }
+   reftable_iterator_destroy(&it);
+   reftable_ref_record_release(&ref);
+*/
+int reftable_reader_seek_ref(struct reftable_reader *r,
+			     struct reftable_iterator *it, const char *name);
+
+/* returns the hash ID used in this table. */
+uint32_t reftable_reader_hash_id(struct reftable_reader *r);
+
+/* seek to logs for the given name, older than update_index. To seek to the
+   start of the table, use name = "".
+*/
+int reftable_reader_seek_log_at(struct reftable_reader *r,
+				struct reftable_iterator *it, const char *name,
+				uint64_t update_index);
+
+/* seek to newest log entry for given name. */
+int reftable_reader_seek_log(struct reftable_reader *r,
+			     struct reftable_iterator *it, const char *name);
+
+/* closes and deallocates a reader. */
+void reftable_reader_free(struct reftable_reader *);
+
+/* return an iterator for the refs pointing to `oid`. */
+int reftable_reader_refs_for(struct reftable_reader *r,
+			     struct reftable_iterator *it, uint8_t *oid);
+
+/* return the max_update_index for a table */
+uint64_t reftable_reader_max_update_index(struct reftable_reader *r);
+
+/* return the min_update_index for a table */
+uint64_t reftable_reader_min_update_index(struct reftable_reader *r);
+
+/* creates a generic table from a file reader. */
+void reftable_table_from_reader(struct reftable_table *tab,
+				struct reftable_reader *reader);
+
+/* print table onto stdout for debugging. */
+int reftable_reader_print_file(const char *tablename);
+
+#endif
diff --git a/reftable/reftable-record.h b/reftable/reftable-record.h
new file mode 100644
index 0000000..5370d22
--- /dev/null
+++ b/reftable/reftable-record.h
@@ -0,0 +1,114 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_RECORD_H
+#define REFTABLE_RECORD_H
+
+#include <stdint.h>
+
+/*
+ * Basic data types
+ *
+ * Reftables store the state of each ref in struct reftable_ref_record, and they
+ * store a sequence of reflog updates in struct reftable_log_record.
+ */
+
+/* reftable_ref_record holds a ref database entry target_value */
+struct reftable_ref_record {
+	char *refname; /* Name of the ref, malloced. */
+	uint64_t update_index; /* Logical timestamp at which this value is
+				* written */
+
+	enum {
+		/* tombstone to hide deletions from earlier tables */
+		REFTABLE_REF_DELETION = 0x0,
+
+		/* a simple ref */
+		REFTABLE_REF_VAL1 = 0x1,
+		/* a tag, plus its peeled hash */
+		REFTABLE_REF_VAL2 = 0x2,
+
+		/* a symbolic reference */
+		REFTABLE_REF_SYMREF = 0x3,
+#define REFTABLE_NR_REF_VALUETYPES 4
+	} value_type;
+	union {
+		uint8_t *val1; /* malloced hash. */
+		struct {
+			uint8_t *value; /* first value, malloced hash  */
+			uint8_t *target_value; /* second value, malloced hash */
+		} val2;
+		char *symref; /* referent, malloced 0-terminated string */
+	} value;
+};
+
+/* Returns the first hash, or NULL if `rec` is not of type
+ * REFTABLE_REF_VAL1 or REFTABLE_REF_VAL2. */
+uint8_t *reftable_ref_record_val1(struct reftable_ref_record *rec);
+
+/* Returns the second hash, or NULL if `rec` is not of type
+ * REFTABLE_REF_VAL2. */
+uint8_t *reftable_ref_record_val2(struct reftable_ref_record *rec);
+
+/* returns whether 'ref' represents a deletion */
+int reftable_ref_record_is_deletion(const struct reftable_ref_record *ref);
+
+/* prints a reftable_ref_record onto stdout. Useful for debugging. */
+void reftable_ref_record_print(struct reftable_ref_record *ref,
+			       uint32_t hash_id);
+
+/* frees and nulls all pointer values inside `ref`. */
+void reftable_ref_record_release(struct reftable_ref_record *ref);
+
+/* returns whether two reftable_ref_records are the same. Useful for testing. */
+int reftable_ref_record_equal(struct reftable_ref_record *a,
+			      struct reftable_ref_record *b, int hash_size);
+
+/* reftable_log_record holds a reflog entry */
+struct reftable_log_record {
+	char *refname;
+	uint64_t update_index; /* logical timestamp of a transactional update.
+				*/
+
+	enum {
+		/* tombstone to hide deletions from earlier tables */
+		REFTABLE_LOG_DELETION = 0x0,
+
+		/* a simple update */
+		REFTABLE_LOG_UPDATE = 0x1,
+#define REFTABLE_NR_LOG_VALUETYPES 2
+	} value_type;
+
+	union {
+		struct {
+			uint8_t *new_hash;
+			uint8_t *old_hash;
+			char *name;
+			char *email;
+			uint64_t time;
+			int16_t tz_offset;
+			char *message;
+		} update;
+	} value;
+};
+
+/* returns whether 'ref' represents the deletion of a log record. */
+int reftable_log_record_is_deletion(const struct reftable_log_record *log);
+
+/* frees and nulls all pointer values. */
+void reftable_log_record_release(struct reftable_log_record *log);
+
+/* returns whether two records are equal. Useful for testing. */
+int reftable_log_record_equal(struct reftable_log_record *a,
+			      struct reftable_log_record *b, int hash_size);
+
+/* dumps a reftable_log_record on stdout, for debugging/testing. */
+void reftable_log_record_print(struct reftable_log_record *log,
+			       uint32_t hash_id);
+
+#endif
diff --git a/reftable/reftable-stack.h b/reftable/reftable-stack.h
new file mode 100644
index 0000000..1b602dd
--- /dev/null
+++ b/reftable/reftable-stack.h
@@ -0,0 +1,128 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_STACK_H
+#define REFTABLE_STACK_H
+
+#include "reftable-writer.h"
+
+/*
+ * The stack presents an interface to a mutable sequence of reftables.
+
+ * A stack can be mutated by pushing a table to the top of the stack.
+
+ * The reftable_stack automatically compacts files on disk to ensure good
+ * amortized performance.
+ *
+ * For windows and other platforms that cannot have open files as rename
+ * destinations, concurrent access from multiple processes needs the rand()
+ * random seed to be randomized.
+ */
+struct reftable_stack;
+
+/* open a new reftable stack. The tables along with the table list will be
+ *  stored in 'dir'. Typically, this should be .git/reftables.
+ */
+int reftable_new_stack(struct reftable_stack **dest, const char *dir,
+		       struct reftable_write_options config);
+
+/* returns the update_index at which a next table should be written. */
+uint64_t reftable_stack_next_update_index(struct reftable_stack *st);
+
+/* holds a transaction to add tables at the top of a stack. */
+struct reftable_addition;
+
+/*
+ * returns a new transaction to add reftables to the given stack. As a side
+ * effect, the ref database is locked.
+ */
+int reftable_stack_new_addition(struct reftable_addition **dest,
+				struct reftable_stack *st);
+
+/* Adds a reftable to transaction. */
+int reftable_addition_add(struct reftable_addition *add,
+			  int (*write_table)(struct reftable_writer *wr,
+					     void *arg),
+			  void *arg);
+
+/* Commits the transaction, releasing the lock. After calling this,
+ * reftable_addition_destroy should still be called.
+ */
+int reftable_addition_commit(struct reftable_addition *add);
+
+/* Release all non-committed data from the transaction, and deallocate the
+ * transaction. Releases the lock if held. */
+void reftable_addition_destroy(struct reftable_addition *add);
+
+/* add a new table to the stack. The write_table function must call
+ * reftable_writer_set_limits, add refs and return an error value. */
+int reftable_stack_add(struct reftable_stack *st,
+		       int (*write_table)(struct reftable_writer *wr,
+					  void *write_arg),
+		       void *write_arg);
+
+/* returns the merged_table for seeking. This table is valid until the
+ * next write or reload, and should not be closed or deleted.
+ */
+struct reftable_merged_table *
+reftable_stack_merged_table(struct reftable_stack *st);
+
+/* frees all resources associated with the stack. */
+void reftable_stack_destroy(struct reftable_stack *st);
+
+/* Reloads the stack if necessary. This is very cheap to run if the stack was up
+ * to date */
+int reftable_stack_reload(struct reftable_stack *st);
+
+/* Policy for expiring reflog entries. */
+struct reftable_log_expiry_config {
+	/* Drop entries older than this timestamp */
+	uint64_t time;
+
+	/* Drop older entries */
+	uint64_t min_update_index;
+};
+
+/* compacts all reftables into a giant table. Expire reflog entries if config is
+ * non-NULL */
+int reftable_stack_compact_all(struct reftable_stack *st,
+			       struct reftable_log_expiry_config *config);
+
+/* heuristically compact unbalanced table stack. */
+int reftable_stack_auto_compact(struct reftable_stack *st);
+
+/* delete stale .ref tables. */
+int reftable_stack_clean(struct reftable_stack *st);
+
+/* convenience function to read a single ref. Returns < 0 for error, 0 for
+ * success, and 1 if ref not found. */
+int reftable_stack_read_ref(struct reftable_stack *st, const char *refname,
+			    struct reftable_ref_record *ref);
+
+/* convenience function to read a single log. Returns < 0 for error, 0 for
+ * success, and 1 if ref not found. */
+int reftable_stack_read_log(struct reftable_stack *st, const char *refname,
+			    struct reftable_log_record *log);
+
+/* statistics on past compactions. */
+struct reftable_compaction_stats {
+	uint64_t bytes; /* total number of bytes written */
+	uint64_t entries_written; /* total number of entries written, including
+				     failures. */
+	int attempts; /* how often we tried to compact */
+	int failures; /* failures happen on concurrent updates */
+};
+
+/* return statistics for compaction up till now. */
+struct reftable_compaction_stats *
+reftable_stack_compaction_stats(struct reftable_stack *st);
+
+/* print the entire stack represented by the directory */
+int reftable_stack_print_directory(const char *stackdir, uint32_t hash_id);
+
+#endif
diff --git a/reftable/reftable-tests.h b/reftable/reftable-tests.h
new file mode 100644
index 0000000..0019cbc
--- /dev/null
+++ b/reftable/reftable-tests.h
@@ -0,0 +1,23 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_TESTS_H
+#define REFTABLE_TESTS_H
+
+int basics_test_main(int argc, const char **argv);
+int block_test_main(int argc, const char **argv);
+int merged_test_main(int argc, const char **argv);
+int pq_test_main(int argc, const char **argv);
+int record_test_main(int argc, const char **argv);
+int refname_test_main(int argc, const char **argv);
+int readwrite_test_main(int argc, const char **argv);
+int stack_test_main(int argc, const char **argv);
+int tree_test_main(int argc, const char **argv);
+int reftable_dump_main(int argc, char *const *argv);
+
+#endif
diff --git a/reftable/reftable-writer.h b/reftable/reftable-writer.h
new file mode 100644
index 0000000..a560dc1
--- /dev/null
+++ b/reftable/reftable-writer.h
@@ -0,0 +1,151 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef REFTABLE_WRITER_H
+#define REFTABLE_WRITER_H
+
+#include "reftable-record.h"
+
+#include <stdint.h>
+#include <unistd.h> /* ssize_t */
+
+/* Writing single reftables */
+
+/* reftable_write_options sets options for writing a single reftable. */
+struct reftable_write_options {
+	/* boolean: do not pad out blocks to block size. */
+	unsigned unpadded : 1;
+
+	/* the blocksize. Should be less than 2^24. */
+	uint32_t block_size;
+
+	/* boolean: do not generate a SHA1 => ref index. */
+	unsigned skip_index_objects : 1;
+
+	/* how often to write complete keys in each block. */
+	int restart_interval;
+
+	/* 4-byte identifier ("sha1", "s256") of the hash.
+	 * Defaults to SHA1 if unset
+	 */
+	uint32_t hash_id;
+
+	/* Default mode for creating files. If unset, use 0666 (+umask) */
+	unsigned int default_permissions;
+
+	/* boolean: do not check ref names for validity or dir/file conflicts.
+	 */
+	unsigned skip_name_check : 1;
+
+	/* boolean: copy log messages exactly. If unset, check that the message
+	 *   is a single line, and add '\n' if missing.
+	 */
+	unsigned exact_log_message : 1;
+};
+
+/* reftable_block_stats holds statistics for a single block type */
+struct reftable_block_stats {
+	/* total number of entries written */
+	int entries;
+	/* total number of key restarts */
+	int restarts;
+	/* total number of blocks */
+	int blocks;
+	/* total number of index blocks */
+	int index_blocks;
+	/* depth of the index */
+	int max_index_level;
+
+	/* offset of the first block for this type */
+	uint64_t offset;
+	/* offset of the top level index block for this type, or 0 if not
+	 * present */
+	uint64_t index_offset;
+};
+
+/* stats holds overall statistics for a single reftable */
+struct reftable_stats {
+	/* total number of blocks written. */
+	int blocks;
+	/* stats for ref data */
+	struct reftable_block_stats ref_stats;
+	/* stats for the SHA1 to ref map. */
+	struct reftable_block_stats obj_stats;
+	/* stats for index blocks */
+	struct reftable_block_stats idx_stats;
+	/* stats for log blocks */
+	struct reftable_block_stats log_stats;
+
+	/* disambiguation length of shortened object IDs. */
+	int object_id_len;
+};
+
+/* reftable_new_writer creates a new writer */
+struct reftable_writer *
+reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
+		    void *writer_arg, struct reftable_write_options *opts);
+
+/* Set the range of update indices for the records we will add. When writing a
+   table into a stack, the min should be at least
+   reftable_stack_next_update_index(), or REFTABLE_API_ERROR is returned.
+
+   For transactional updates to a stack, typically min==max, and the
+   update_index can be obtained by inspeciting the stack. When converting an
+   existing ref database into a single reftable, this would be a range of
+   update-index timestamps.
+ */
+void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
+				uint64_t max);
+
+/*
+  Add a reftable_ref_record. The record should have names that come after
+  already added records.
+
+  The update_index must be within the limits set by
+  reftable_writer_set_limits(), or REFTABLE_API_ERROR is returned. It is an
+  REFTABLE_API_ERROR error to write a ref record after a log record.
+*/
+int reftable_writer_add_ref(struct reftable_writer *w,
+			    struct reftable_ref_record *ref);
+
+/*
+  Convenience function to add multiple reftable_ref_records; the function sorts
+  the records before adding them, reordering the records array passed in.
+*/
+int reftable_writer_add_refs(struct reftable_writer *w,
+			     struct reftable_ref_record *refs, int n);
+
+/*
+  adds reftable_log_records. Log records are keyed by (refname, decreasing
+  update_index). The key for the record added must come after the already added
+  log records.
+*/
+int reftable_writer_add_log(struct reftable_writer *w,
+			    struct reftable_log_record *log);
+
+/*
+  Convenience function to add multiple reftable_log_records; the function sorts
+  the records before adding them, reordering records array passed in.
+*/
+int reftable_writer_add_logs(struct reftable_writer *w,
+			     struct reftable_log_record *logs, int n);
+
+/* reftable_writer_close finalizes the reftable. The writer is retained so
+ * statistics can be inspected. */
+int reftable_writer_close(struct reftable_writer *w);
+
+/* writer_stats returns the statistics on the reftable being written.
+
+   This struct becomes invalid when the writer is freed.
+ */
+const struct reftable_stats *writer_stats(struct reftable_writer *w);
+
+/* reftable_writer_free deallocates memory for the writer */
+void reftable_writer_free(struct reftable_writer *w);
+
+#endif
diff --git a/reftable/reftable.c b/reftable/reftable.c
new file mode 100644
index 0000000..0e4607a
--- /dev/null
+++ b/reftable/reftable.c
@@ -0,0 +1,115 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "basics.h"
+#include "record.h"
+#include "generic.h"
+#include "reftable-iterator.h"
+#include "reftable-generic.h"
+
+int reftable_table_seek_ref(struct reftable_table *tab,
+			    struct reftable_iterator *it, const char *name)
+{
+	struct reftable_ref_record ref = {
+		.refname = (char *)name,
+	};
+	struct reftable_record rec = { NULL };
+	reftable_record_from_ref(&rec, &ref);
+	return tab->ops->seek_record(tab->table_arg, it, &rec);
+}
+
+int reftable_table_read_ref(struct reftable_table *tab, const char *name,
+			    struct reftable_ref_record *ref)
+{
+	struct reftable_iterator it = { NULL };
+	int err = reftable_table_seek_ref(tab, &it, name);
+	if (err)
+		goto done;
+
+	err = reftable_iterator_next_ref(&it, ref);
+	if (err)
+		goto done;
+
+	if (strcmp(ref->refname, name) ||
+	    reftable_ref_record_is_deletion(ref)) {
+		reftable_ref_record_release(ref);
+		err = 1;
+		goto done;
+	}
+
+done:
+	reftable_iterator_destroy(&it);
+	return err;
+}
+
+uint64_t reftable_table_max_update_index(struct reftable_table *tab)
+{
+	return tab->ops->max_update_index(tab->table_arg);
+}
+
+uint64_t reftable_table_min_update_index(struct reftable_table *tab)
+{
+	return tab->ops->min_update_index(tab->table_arg);
+}
+
+uint32_t reftable_table_hash_id(struct reftable_table *tab)
+{
+	return tab->ops->hash_id(tab->table_arg);
+}
+
+void reftable_iterator_destroy(struct reftable_iterator *it)
+{
+	if (!it->ops) {
+		return;
+	}
+	it->ops->close(it->iter_arg);
+	it->ops = NULL;
+	FREE_AND_NULL(it->iter_arg);
+}
+
+int reftable_iterator_next_ref(struct reftable_iterator *it,
+			       struct reftable_ref_record *ref)
+{
+	struct reftable_record rec = { NULL };
+	reftable_record_from_ref(&rec, ref);
+	return iterator_next(it, &rec);
+}
+
+int reftable_iterator_next_log(struct reftable_iterator *it,
+			       struct reftable_log_record *log)
+{
+	struct reftable_record rec = { NULL };
+	reftable_record_from_log(&rec, log);
+	return iterator_next(it, &rec);
+}
+
+int iterator_next(struct reftable_iterator *it, struct reftable_record *rec)
+{
+	return it->ops->next(it->iter_arg, rec);
+}
+
+static int empty_iterator_next(void *arg, struct reftable_record *rec)
+{
+	return 1;
+}
+
+static void empty_iterator_close(void *arg)
+{
+}
+
+static struct reftable_iterator_vtable empty_vtable = {
+	.next = &empty_iterator_next,
+	.close = &empty_iterator_close,
+};
+
+void iterator_set_empty(struct reftable_iterator *it)
+{
+	assert(!it->ops);
+	it->iter_arg = NULL;
+	it->ops = &empty_vtable;
+}
diff --git a/reftable/stack.c b/reftable/stack.c
new file mode 100644
index 0000000..56bf5f2
--- /dev/null
+++ b/reftable/stack.c
@@ -0,0 +1,1414 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "stack.h"
+
+#include "system.h"
+#include "merged.h"
+#include "reader.h"
+#include "refname.h"
+#include "reftable-error.h"
+#include "reftable-record.h"
+#include "reftable-merged.h"
+#include "writer.h"
+
+static int stack_try_add(struct reftable_stack *st,
+			 int (*write_table)(struct reftable_writer *wr,
+					    void *arg),
+			 void *arg);
+static int stack_write_compact(struct reftable_stack *st,
+			       struct reftable_writer *wr, int first, int last,
+			       struct reftable_log_expiry_config *config);
+static int stack_check_addition(struct reftable_stack *st,
+				const char *new_tab_name);
+static void reftable_addition_close(struct reftable_addition *add);
+static int reftable_stack_reload_maybe_reuse(struct reftable_stack *st,
+					     int reuse_open);
+
+static void stack_filename(struct strbuf *dest, struct reftable_stack *st,
+			   const char *name)
+{
+	strbuf_reset(dest);
+	strbuf_addstr(dest, st->reftable_dir);
+	strbuf_addstr(dest, "/");
+	strbuf_addstr(dest, name);
+}
+
+static ssize_t reftable_fd_write(void *arg, const void *data, size_t sz)
+{
+	int *fdp = (int *)arg;
+	return write(*fdp, data, sz);
+}
+
+int reftable_new_stack(struct reftable_stack **dest, const char *dir,
+		       struct reftable_write_options config)
+{
+	struct reftable_stack *p =
+		reftable_calloc(sizeof(struct reftable_stack));
+	struct strbuf list_file_name = STRBUF_INIT;
+	int err = 0;
+
+	if (config.hash_id == 0) {
+		config.hash_id = GIT_SHA1_FORMAT_ID;
+	}
+
+	*dest = NULL;
+
+	strbuf_reset(&list_file_name);
+	strbuf_addstr(&list_file_name, dir);
+	strbuf_addstr(&list_file_name, "/tables.list");
+
+	p->list_file = strbuf_detach(&list_file_name, NULL);
+	p->reftable_dir = xstrdup(dir);
+	p->config = config;
+
+	err = reftable_stack_reload_maybe_reuse(p, 1);
+	if (err < 0) {
+		reftable_stack_destroy(p);
+	} else {
+		*dest = p;
+	}
+	return err;
+}
+
+static int fd_read_lines(int fd, char ***namesp)
+{
+	off_t size = lseek(fd, 0, SEEK_END);
+	char *buf = NULL;
+	int err = 0;
+	if (size < 0) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+	err = lseek(fd, 0, SEEK_SET);
+	if (err < 0) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+
+	buf = reftable_malloc(size + 1);
+	if (read(fd, buf, size) != size) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+	buf[size] = 0;
+
+	parse_names(buf, size, namesp);
+
+done:
+	reftable_free(buf);
+	return err;
+}
+
+int read_lines(const char *filename, char ***namesp)
+{
+	int fd = open(filename, O_RDONLY);
+	int err = 0;
+	if (fd < 0) {
+		if (errno == ENOENT) {
+			*namesp = reftable_calloc(sizeof(char *));
+			return 0;
+		}
+
+		return REFTABLE_IO_ERROR;
+	}
+	err = fd_read_lines(fd, namesp);
+	close(fd);
+	return err;
+}
+
+struct reftable_merged_table *
+reftable_stack_merged_table(struct reftable_stack *st)
+{
+	return st->merged;
+}
+
+static int has_name(char **names, const char *name)
+{
+	while (*names) {
+		if (!strcmp(*names, name))
+			return 1;
+		names++;
+	}
+	return 0;
+}
+
+/* Close and free the stack */
+void reftable_stack_destroy(struct reftable_stack *st)
+{
+	char **names = NULL;
+	int err = 0;
+	if (st->merged) {
+		reftable_merged_table_free(st->merged);
+		st->merged = NULL;
+	}
+
+	err = read_lines(st->list_file, &names);
+	if (err < 0) {
+		FREE_AND_NULL(names);
+	}
+
+	if (st->readers) {
+		int i = 0;
+		struct strbuf filename = STRBUF_INIT;
+		for (i = 0; i < st->readers_len; i++) {
+			const char *name = reader_name(st->readers[i]);
+			strbuf_reset(&filename);
+			if (names && !has_name(names, name)) {
+				stack_filename(&filename, st, name);
+			}
+			reftable_reader_free(st->readers[i]);
+
+			if (filename.len) {
+				/* On Windows, can only unlink after closing. */
+				unlink(filename.buf);
+			}
+		}
+		strbuf_release(&filename);
+		st->readers_len = 0;
+		FREE_AND_NULL(st->readers);
+	}
+	FREE_AND_NULL(st->list_file);
+	FREE_AND_NULL(st->reftable_dir);
+	reftable_free(st);
+	free_names(names);
+}
+
+static struct reftable_reader **stack_copy_readers(struct reftable_stack *st,
+						   int cur_len)
+{
+	struct reftable_reader **cur =
+		reftable_calloc(sizeof(struct reftable_reader *) * cur_len);
+	int i = 0;
+	for (i = 0; i < cur_len; i++) {
+		cur[i] = st->readers[i];
+	}
+	return cur;
+}
+
+static int reftable_stack_reload_once(struct reftable_stack *st, char **names,
+				      int reuse_open)
+{
+	int cur_len = !st->merged ? 0 : st->merged->stack_len;
+	struct reftable_reader **cur = stack_copy_readers(st, cur_len);
+	int err = 0;
+	int names_len = names_length(names);
+	struct reftable_reader **new_readers =
+		reftable_calloc(sizeof(struct reftable_reader *) * names_len);
+	struct reftable_table *new_tables =
+		reftable_calloc(sizeof(struct reftable_table) * names_len);
+	int new_readers_len = 0;
+	struct reftable_merged_table *new_merged = NULL;
+	int i;
+
+	while (*names) {
+		struct reftable_reader *rd = NULL;
+		char *name = *names++;
+
+		/* this is linear; we assume compaction keeps the number of
+		   tables under control so this is not quadratic. */
+		int j = 0;
+		for (j = 0; reuse_open && j < cur_len; j++) {
+			if (cur[j] && 0 == strcmp(cur[j]->name, name)) {
+				rd = cur[j];
+				cur[j] = NULL;
+				break;
+			}
+		}
+
+		if (!rd) {
+			struct reftable_block_source src = { NULL };
+			struct strbuf table_path = STRBUF_INIT;
+			stack_filename(&table_path, st, name);
+
+			err = reftable_block_source_from_file(&src,
+							      table_path.buf);
+			strbuf_release(&table_path);
+
+			if (err < 0)
+				goto done;
+
+			err = reftable_new_reader(&rd, &src, name);
+			if (err < 0)
+				goto done;
+		}
+
+		new_readers[new_readers_len] = rd;
+		reftable_table_from_reader(&new_tables[new_readers_len], rd);
+		new_readers_len++;
+	}
+
+	/* success! */
+	err = reftable_new_merged_table(&new_merged, new_tables,
+					new_readers_len, st->config.hash_id);
+	if (err < 0)
+		goto done;
+
+	new_tables = NULL;
+	st->readers_len = new_readers_len;
+	if (st->merged) {
+		merged_table_release(st->merged);
+		reftable_merged_table_free(st->merged);
+	}
+	if (st->readers) {
+		reftable_free(st->readers);
+	}
+	st->readers = new_readers;
+	new_readers = NULL;
+	new_readers_len = 0;
+
+	new_merged->suppress_deletions = 1;
+	st->merged = new_merged;
+	for (i = 0; i < cur_len; i++) {
+		if (cur[i]) {
+			const char *name = reader_name(cur[i]);
+			struct strbuf filename = STRBUF_INIT;
+			stack_filename(&filename, st, name);
+
+			reader_close(cur[i]);
+			reftable_reader_free(cur[i]);
+
+			/* On Windows, can only unlink after closing. */
+			unlink(filename.buf);
+
+			strbuf_release(&filename);
+		}
+	}
+
+done:
+	for (i = 0; i < new_readers_len; i++) {
+		reader_close(new_readers[i]);
+		reftable_reader_free(new_readers[i]);
+	}
+	reftable_free(new_readers);
+	reftable_free(new_tables);
+	reftable_free(cur);
+	return err;
+}
+
+/* return negative if a before b. */
+static int tv_cmp(struct timeval *a, struct timeval *b)
+{
+	time_t diff = a->tv_sec - b->tv_sec;
+	int udiff = a->tv_usec - b->tv_usec;
+
+	if (diff != 0)
+		return diff;
+
+	return udiff;
+}
+
+static int reftable_stack_reload_maybe_reuse(struct reftable_stack *st,
+					     int reuse_open)
+{
+	struct timeval deadline = { 0 };
+	int err = gettimeofday(&deadline, NULL);
+	int64_t delay = 0;
+	int tries = 0;
+	if (err < 0)
+		return err;
+
+	deadline.tv_sec += 3;
+	while (1) {
+		char **names = NULL;
+		char **names_after = NULL;
+		struct timeval now = { 0 };
+		int err = gettimeofday(&now, NULL);
+		int err2 = 0;
+		if (err < 0) {
+			return err;
+		}
+
+		/* Only look at deadlines after the first few times. This
+		   simplifies debugging in GDB */
+		tries++;
+		if (tries > 3 && tv_cmp(&now, &deadline) >= 0) {
+			break;
+		}
+
+		err = read_lines(st->list_file, &names);
+		if (err < 0) {
+			free_names(names);
+			return err;
+		}
+		err = reftable_stack_reload_once(st, names, reuse_open);
+		if (err == 0) {
+			free_names(names);
+			break;
+		}
+		if (err != REFTABLE_NOT_EXIST_ERROR) {
+			free_names(names);
+			return err;
+		}
+
+		/* err == REFTABLE_NOT_EXIST_ERROR can be caused by a concurrent
+		   writer. Check if there was one by checking if the name list
+		   changed.
+		*/
+		err2 = read_lines(st->list_file, &names_after);
+		if (err2 < 0) {
+			free_names(names);
+			return err2;
+		}
+
+		if (names_equal(names_after, names)) {
+			free_names(names);
+			free_names(names_after);
+			return err;
+		}
+		free_names(names);
+		free_names(names_after);
+
+		delay = delay + (delay * rand()) / RAND_MAX + 1;
+		sleep_millisec(delay);
+	}
+
+	return 0;
+}
+
+/* -1 = error
+ 0 = up to date
+ 1 = changed. */
+static int stack_uptodate(struct reftable_stack *st)
+{
+	char **names = NULL;
+	int err = read_lines(st->list_file, &names);
+	int i = 0;
+	if (err < 0)
+		return err;
+
+	for (i = 0; i < st->readers_len; i++) {
+		if (!names[i]) {
+			err = 1;
+			goto done;
+		}
+
+		if (strcmp(st->readers[i]->name, names[i])) {
+			err = 1;
+			goto done;
+		}
+	}
+
+	if (names[st->merged->stack_len]) {
+		err = 1;
+		goto done;
+	}
+
+done:
+	free_names(names);
+	return err;
+}
+
+int reftable_stack_reload(struct reftable_stack *st)
+{
+	int err = stack_uptodate(st);
+	if (err > 0)
+		return reftable_stack_reload_maybe_reuse(st, 1);
+	return err;
+}
+
+int reftable_stack_add(struct reftable_stack *st,
+		       int (*write)(struct reftable_writer *wr, void *arg),
+		       void *arg)
+{
+	int err = stack_try_add(st, write, arg);
+	if (err < 0) {
+		if (err == REFTABLE_LOCK_ERROR) {
+			/* Ignore error return, we want to propagate
+			   REFTABLE_LOCK_ERROR.
+			*/
+			reftable_stack_reload(st);
+		}
+		return err;
+	}
+
+	if (!st->disable_auto_compact)
+		return reftable_stack_auto_compact(st);
+
+	return 0;
+}
+
+static void format_name(struct strbuf *dest, uint64_t min, uint64_t max)
+{
+	char buf[100];
+	uint32_t rnd = (uint32_t)rand();
+	snprintf(buf, sizeof(buf), "0x%012" PRIx64 "-0x%012" PRIx64 "-%08x",
+		 min, max, rnd);
+	strbuf_reset(dest);
+	strbuf_addstr(dest, buf);
+}
+
+struct reftable_addition {
+	int lock_file_fd;
+	struct strbuf lock_file_name;
+	struct reftable_stack *stack;
+
+	char **new_tables;
+	int new_tables_len;
+	uint64_t next_update_index;
+};
+
+#define REFTABLE_ADDITION_INIT                \
+	{                                     \
+		.lock_file_name = STRBUF_INIT \
+	}
+
+static int reftable_stack_init_addition(struct reftable_addition *add,
+					struct reftable_stack *st)
+{
+	int err = 0;
+	add->stack = st;
+
+	strbuf_reset(&add->lock_file_name);
+	strbuf_addstr(&add->lock_file_name, st->list_file);
+	strbuf_addstr(&add->lock_file_name, ".lock");
+
+	add->lock_file_fd = open(add->lock_file_name.buf,
+				 O_EXCL | O_CREAT | O_WRONLY, 0666);
+	if (add->lock_file_fd < 0) {
+		if (errno == EEXIST) {
+			err = REFTABLE_LOCK_ERROR;
+		} else {
+			err = REFTABLE_IO_ERROR;
+		}
+		goto done;
+	}
+	if (st->config.default_permissions) {
+		if (chmod(add->lock_file_name.buf, st->config.default_permissions) < 0) {
+			err = REFTABLE_IO_ERROR;
+			goto done;
+		}
+	}
+
+	err = stack_uptodate(st);
+	if (err < 0)
+		goto done;
+
+	if (err > 1) {
+		err = REFTABLE_LOCK_ERROR;
+		goto done;
+	}
+
+	add->next_update_index = reftable_stack_next_update_index(st);
+done:
+	if (err) {
+		reftable_addition_close(add);
+	}
+	return err;
+}
+
+static void reftable_addition_close(struct reftable_addition *add)
+{
+	int i = 0;
+	struct strbuf nm = STRBUF_INIT;
+	for (i = 0; i < add->new_tables_len; i++) {
+		stack_filename(&nm, add->stack, add->new_tables[i]);
+		unlink(nm.buf);
+		reftable_free(add->new_tables[i]);
+		add->new_tables[i] = NULL;
+	}
+	reftable_free(add->new_tables);
+	add->new_tables = NULL;
+	add->new_tables_len = 0;
+
+	if (add->lock_file_fd > 0) {
+		close(add->lock_file_fd);
+		add->lock_file_fd = 0;
+	}
+	if (add->lock_file_name.len > 0) {
+		unlink(add->lock_file_name.buf);
+		strbuf_release(&add->lock_file_name);
+	}
+
+	strbuf_release(&nm);
+}
+
+void reftable_addition_destroy(struct reftable_addition *add)
+{
+	if (!add) {
+		return;
+	}
+	reftable_addition_close(add);
+	reftable_free(add);
+}
+
+int reftable_addition_commit(struct reftable_addition *add)
+{
+	struct strbuf table_list = STRBUF_INIT;
+	int i = 0;
+	int err = 0;
+	if (add->new_tables_len == 0)
+		goto done;
+
+	for (i = 0; i < add->stack->merged->stack_len; i++) {
+		strbuf_addstr(&table_list, add->stack->readers[i]->name);
+		strbuf_addstr(&table_list, "\n");
+	}
+	for (i = 0; i < add->new_tables_len; i++) {
+		strbuf_addstr(&table_list, add->new_tables[i]);
+		strbuf_addstr(&table_list, "\n");
+	}
+
+	err = write(add->lock_file_fd, table_list.buf, table_list.len);
+	strbuf_release(&table_list);
+	if (err < 0) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+
+	err = close(add->lock_file_fd);
+	add->lock_file_fd = 0;
+	if (err < 0) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+
+	err = rename(add->lock_file_name.buf, add->stack->list_file);
+	if (err < 0) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+
+	/* success, no more state to clean up. */
+	strbuf_release(&add->lock_file_name);
+	for (i = 0; i < add->new_tables_len; i++) {
+		reftable_free(add->new_tables[i]);
+	}
+	reftable_free(add->new_tables);
+	add->new_tables = NULL;
+	add->new_tables_len = 0;
+
+	err = reftable_stack_reload(add->stack);
+done:
+	reftable_addition_close(add);
+	return err;
+}
+
+int reftable_stack_new_addition(struct reftable_addition **dest,
+				struct reftable_stack *st)
+{
+	int err = 0;
+	struct reftable_addition empty = REFTABLE_ADDITION_INIT;
+	*dest = reftable_calloc(sizeof(**dest));
+	**dest = empty;
+	err = reftable_stack_init_addition(*dest, st);
+	if (err) {
+		reftable_free(*dest);
+		*dest = NULL;
+	}
+	return err;
+}
+
+static int stack_try_add(struct reftable_stack *st,
+			 int (*write_table)(struct reftable_writer *wr,
+					    void *arg),
+			 void *arg)
+{
+	struct reftable_addition add = REFTABLE_ADDITION_INIT;
+	int err = reftable_stack_init_addition(&add, st);
+	if (err < 0)
+		goto done;
+	if (err > 0) {
+		err = REFTABLE_LOCK_ERROR;
+		goto done;
+	}
+
+	err = reftable_addition_add(&add, write_table, arg);
+	if (err < 0)
+		goto done;
+
+	err = reftable_addition_commit(&add);
+done:
+	reftable_addition_close(&add);
+	return err;
+}
+
+int reftable_addition_add(struct reftable_addition *add,
+			  int (*write_table)(struct reftable_writer *wr,
+					     void *arg),
+			  void *arg)
+{
+	struct strbuf temp_tab_file_name = STRBUF_INIT;
+	struct strbuf tab_file_name = STRBUF_INIT;
+	struct strbuf next_name = STRBUF_INIT;
+	struct reftable_writer *wr = NULL;
+	int err = 0;
+	int tab_fd = 0;
+
+	strbuf_reset(&next_name);
+	format_name(&next_name, add->next_update_index, add->next_update_index);
+
+	stack_filename(&temp_tab_file_name, add->stack, next_name.buf);
+	strbuf_addstr(&temp_tab_file_name, ".temp.XXXXXX");
+
+	tab_fd = mkstemp(temp_tab_file_name.buf);
+	if (tab_fd < 0) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+	if (add->stack->config.default_permissions) {
+		if (chmod(temp_tab_file_name.buf, add->stack->config.default_permissions)) {
+			err = REFTABLE_IO_ERROR;
+			goto done;
+		}
+	}
+	wr = reftable_new_writer(reftable_fd_write, &tab_fd,
+				 &add->stack->config);
+	err = write_table(wr, arg);
+	if (err < 0)
+		goto done;
+
+	err = reftable_writer_close(wr);
+	if (err == REFTABLE_EMPTY_TABLE_ERROR) {
+		err = 0;
+		goto done;
+	}
+	if (err < 0)
+		goto done;
+
+	err = close(tab_fd);
+	tab_fd = 0;
+	if (err < 0) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+
+	err = stack_check_addition(add->stack, temp_tab_file_name.buf);
+	if (err < 0)
+		goto done;
+
+	if (wr->min_update_index < add->next_update_index) {
+		err = REFTABLE_API_ERROR;
+		goto done;
+	}
+
+	format_name(&next_name, wr->min_update_index, wr->max_update_index);
+	strbuf_addstr(&next_name, ".ref");
+
+	stack_filename(&tab_file_name, add->stack, next_name.buf);
+
+	/*
+	  On windows, this relies on rand() picking a unique destination name.
+	  Maybe we should do retry loop as well?
+	 */
+	err = rename(temp_tab_file_name.buf, tab_file_name.buf);
+	if (err < 0) {
+		err = REFTABLE_IO_ERROR;
+		goto done;
+	}
+
+	add->new_tables = reftable_realloc(add->new_tables,
+					   sizeof(*add->new_tables) *
+						   (add->new_tables_len + 1));
+	add->new_tables[add->new_tables_len] = strbuf_detach(&next_name, NULL);
+	add->new_tables_len++;
+done:
+	if (tab_fd > 0) {
+		close(tab_fd);
+		tab_fd = 0;
+	}
+	if (temp_tab_file_name.len > 0) {
+		unlink(temp_tab_file_name.buf);
+	}
+
+	strbuf_release(&temp_tab_file_name);
+	strbuf_release(&tab_file_name);
+	strbuf_release(&next_name);
+	reftable_writer_free(wr);
+	return err;
+}
+
+uint64_t reftable_stack_next_update_index(struct reftable_stack *st)
+{
+	int sz = st->merged->stack_len;
+	if (sz > 0)
+		return reftable_reader_max_update_index(st->readers[sz - 1]) +
+		       1;
+	return 1;
+}
+
+static int stack_compact_locked(struct reftable_stack *st, int first, int last,
+				struct strbuf *temp_tab,
+				struct reftable_log_expiry_config *config)
+{
+	struct strbuf next_name = STRBUF_INIT;
+	int tab_fd = -1;
+	struct reftable_writer *wr = NULL;
+	int err = 0;
+
+	format_name(&next_name,
+		    reftable_reader_min_update_index(st->readers[first]),
+		    reftable_reader_max_update_index(st->readers[last]));
+
+	stack_filename(temp_tab, st, next_name.buf);
+	strbuf_addstr(temp_tab, ".temp.XXXXXX");
+
+	tab_fd = mkstemp(temp_tab->buf);
+	wr = reftable_new_writer(reftable_fd_write, &tab_fd, &st->config);
+
+	err = stack_write_compact(st, wr, first, last, config);
+	if (err < 0)
+		goto done;
+	err = reftable_writer_close(wr);
+	if (err < 0)
+		goto done;
+
+	err = close(tab_fd);
+	tab_fd = 0;
+
+done:
+	reftable_writer_free(wr);
+	if (tab_fd > 0) {
+		close(tab_fd);
+		tab_fd = 0;
+	}
+	if (err != 0 && temp_tab->len > 0) {
+		unlink(temp_tab->buf);
+		strbuf_release(temp_tab);
+	}
+	strbuf_release(&next_name);
+	return err;
+}
+
+static int stack_write_compact(struct reftable_stack *st,
+			       struct reftable_writer *wr, int first, int last,
+			       struct reftable_log_expiry_config *config)
+{
+	int subtabs_len = last - first + 1;
+	struct reftable_table *subtabs = reftable_calloc(
+		sizeof(struct reftable_table) * (last - first + 1));
+	struct reftable_merged_table *mt = NULL;
+	int err = 0;
+	struct reftable_iterator it = { NULL };
+	struct reftable_ref_record ref = { NULL };
+	struct reftable_log_record log = { NULL };
+
+	uint64_t entries = 0;
+
+	int i = 0, j = 0;
+	for (i = first, j = 0; i <= last; i++) {
+		struct reftable_reader *t = st->readers[i];
+		reftable_table_from_reader(&subtabs[j++], t);
+		st->stats.bytes += t->size;
+	}
+	reftable_writer_set_limits(wr, st->readers[first]->min_update_index,
+				   st->readers[last]->max_update_index);
+
+	err = reftable_new_merged_table(&mt, subtabs, subtabs_len,
+					st->config.hash_id);
+	if (err < 0) {
+		reftable_free(subtabs);
+		goto done;
+	}
+
+	err = reftable_merged_table_seek_ref(mt, &it, "");
+	if (err < 0)
+		goto done;
+
+	while (1) {
+		err = reftable_iterator_next_ref(&it, &ref);
+		if (err > 0) {
+			err = 0;
+			break;
+		}
+		if (err < 0) {
+			break;
+		}
+
+		if (first == 0 && reftable_ref_record_is_deletion(&ref)) {
+			continue;
+		}
+
+		err = reftable_writer_add_ref(wr, &ref);
+		if (err < 0) {
+			break;
+		}
+		entries++;
+	}
+	reftable_iterator_destroy(&it);
+
+	err = reftable_merged_table_seek_log(mt, &it, "");
+	if (err < 0)
+		goto done;
+
+	while (1) {
+		err = reftable_iterator_next_log(&it, &log);
+		if (err > 0) {
+			err = 0;
+			break;
+		}
+		if (err < 0) {
+			break;
+		}
+		if (first == 0 && reftable_log_record_is_deletion(&log)) {
+			continue;
+		}
+
+		if (config && config->min_update_index > 0 &&
+		    log.update_index < config->min_update_index) {
+			continue;
+		}
+
+		if (config && config->time > 0 &&
+		    log.value.update.time < config->time) {
+			continue;
+		}
+
+		err = reftable_writer_add_log(wr, &log);
+		if (err < 0) {
+			break;
+		}
+		entries++;
+	}
+
+done:
+	reftable_iterator_destroy(&it);
+	if (mt) {
+		merged_table_release(mt);
+		reftable_merged_table_free(mt);
+	}
+	reftable_ref_record_release(&ref);
+	reftable_log_record_release(&log);
+	st->stats.entries_written += entries;
+	return err;
+}
+
+/* <  0: error. 0 == OK, > 0 attempt failed; could retry. */
+static int stack_compact_range(struct reftable_stack *st, int first, int last,
+			       struct reftable_log_expiry_config *expiry)
+{
+	struct strbuf temp_tab_file_name = STRBUF_INIT;
+	struct strbuf new_table_name = STRBUF_INIT;
+	struct strbuf lock_file_name = STRBUF_INIT;
+	struct strbuf ref_list_contents = STRBUF_INIT;
+	struct strbuf new_table_path = STRBUF_INIT;
+	int err = 0;
+	int have_lock = 0;
+	int lock_file_fd = 0;
+	int compact_count = last - first + 1;
+	char **listp = NULL;
+	char **delete_on_success =
+		reftable_calloc(sizeof(char *) * (compact_count + 1));
+	char **subtable_locks =
+		reftable_calloc(sizeof(char *) * (compact_count + 1));
+	int i = 0;
+	int j = 0;
+	int is_empty_table = 0;
+
+	if (first > last || (!expiry && first == last)) {
+		err = 0;
+		goto done;
+	}
+
+	st->stats.attempts++;
+
+	strbuf_reset(&lock_file_name);
+	strbuf_addstr(&lock_file_name, st->list_file);
+	strbuf_addstr(&lock_file_name, ".lock");
+
+	lock_file_fd =
+		open(lock_file_name.buf, O_EXCL | O_CREAT | O_WRONLY, 0666);
+	if (lock_file_fd < 0) {
+		if (errno == EEXIST) {
+			err = 1;
+		} else {
+			err = REFTABLE_IO_ERROR;
+		}
+		goto done;
+	}
+	/* Don't want to write to the lock for now.  */
+	close(lock_file_fd);
+	lock_file_fd = 0;
+
+	have_lock = 1;
+	err = stack_uptodate(st);
+	if (err != 0)
+		goto done;
+
+	for (i = first, j = 0; i <= last; i++) {
+		struct strbuf subtab_file_name = STRBUF_INIT;
+		struct strbuf subtab_lock = STRBUF_INIT;
+		int sublock_file_fd = -1;
+
+		stack_filename(&subtab_file_name, st,
+			       reader_name(st->readers[i]));
+
+		strbuf_reset(&subtab_lock);
+		strbuf_addbuf(&subtab_lock, &subtab_file_name);
+		strbuf_addstr(&subtab_lock, ".lock");
+
+		sublock_file_fd = open(subtab_lock.buf,
+				       O_EXCL | O_CREAT | O_WRONLY, 0666);
+		if (sublock_file_fd >= 0) {
+			close(sublock_file_fd);
+		} else if (sublock_file_fd < 0) {
+			if (errno == EEXIST) {
+				err = 1;
+			} else {
+				err = REFTABLE_IO_ERROR;
+			}
+		}
+
+		subtable_locks[j] = subtab_lock.buf;
+		delete_on_success[j] = subtab_file_name.buf;
+		j++;
+
+		if (err != 0)
+			goto done;
+	}
+
+	err = unlink(lock_file_name.buf);
+	if (err < 0)
+		goto done;
+	have_lock = 0;
+
+	err = stack_compact_locked(st, first, last, &temp_tab_file_name,
+				   expiry);
+	/* Compaction + tombstones can create an empty table out of non-empty
+	 * tables. */
+	is_empty_table = (err == REFTABLE_EMPTY_TABLE_ERROR);
+	if (is_empty_table) {
+		err = 0;
+	}
+	if (err < 0)
+		goto done;
+
+	lock_file_fd =
+		open(lock_file_name.buf, O_EXCL | O_CREAT | O_WRONLY, 0666);
+	if (lock_file_fd < 0) {
+		if (errno == EEXIST) {
+			err = 1;
+		} else {
+			err = REFTABLE_IO_ERROR;
+		}
+		goto done;
+	}
+	have_lock = 1;
+	if (st->config.default_permissions) {
+		if (chmod(lock_file_name.buf, st->config.default_permissions) < 0) {
+			err = REFTABLE_IO_ERROR;
+			goto done;
+		}
+	}
+
+	format_name(&new_table_name, st->readers[first]->min_update_index,
+		    st->readers[last]->max_update_index);
+	strbuf_addstr(&new_table_name, ".ref");
+
+	stack_filename(&new_table_path, st, new_table_name.buf);
+
+	if (!is_empty_table) {
+		/* retry? */
+		err = rename(temp_tab_file_name.buf, new_table_path.buf);
+		if (err < 0) {
+			err = REFTABLE_IO_ERROR;
+			goto done;
+		}
+	}
+
+	for (i = 0; i < first; i++) {
+		strbuf_addstr(&ref_list_contents, st->readers[i]->name);
+		strbuf_addstr(&ref_list_contents, "\n");
+	}
+	if (!is_empty_table) {
+		strbuf_addbuf(&ref_list_contents, &new_table_name);
+		strbuf_addstr(&ref_list_contents, "\n");
+	}
+	for (i = last + 1; i < st->merged->stack_len; i++) {
+		strbuf_addstr(&ref_list_contents, st->readers[i]->name);
+		strbuf_addstr(&ref_list_contents, "\n");
+	}
+
+	err = write(lock_file_fd, ref_list_contents.buf, ref_list_contents.len);
+	if (err < 0) {
+		err = REFTABLE_IO_ERROR;
+		unlink(new_table_path.buf);
+		goto done;
+	}
+	err = close(lock_file_fd);
+	lock_file_fd = 0;
+	if (err < 0) {
+		err = REFTABLE_IO_ERROR;
+		unlink(new_table_path.buf);
+		goto done;
+	}
+
+	err = rename(lock_file_name.buf, st->list_file);
+	if (err < 0) {
+		err = REFTABLE_IO_ERROR;
+		unlink(new_table_path.buf);
+		goto done;
+	}
+	have_lock = 0;
+
+	/* Reload the stack before deleting. On windows, we can only delete the
+	   files after we closed them.
+	*/
+	err = reftable_stack_reload_maybe_reuse(st, first < last);
+
+	listp = delete_on_success;
+	while (*listp) {
+		if (strcmp(*listp, new_table_path.buf)) {
+			unlink(*listp);
+		}
+		listp++;
+	}
+
+done:
+	free_names(delete_on_success);
+
+	listp = subtable_locks;
+	while (*listp) {
+		unlink(*listp);
+		listp++;
+	}
+	free_names(subtable_locks);
+	if (lock_file_fd > 0) {
+		close(lock_file_fd);
+		lock_file_fd = 0;
+	}
+	if (have_lock) {
+		unlink(lock_file_name.buf);
+	}
+	strbuf_release(&new_table_name);
+	strbuf_release(&new_table_path);
+	strbuf_release(&ref_list_contents);
+	strbuf_release(&temp_tab_file_name);
+	strbuf_release(&lock_file_name);
+	return err;
+}
+
+int reftable_stack_compact_all(struct reftable_stack *st,
+			       struct reftable_log_expiry_config *config)
+{
+	return stack_compact_range(st, 0, st->merged->stack_len - 1, config);
+}
+
+static int stack_compact_range_stats(struct reftable_stack *st, int first,
+				     int last,
+				     struct reftable_log_expiry_config *config)
+{
+	int err = stack_compact_range(st, first, last, config);
+	if (err > 0) {
+		st->stats.failures++;
+	}
+	return err;
+}
+
+static int segment_size(struct segment *s)
+{
+	return s->end - s->start;
+}
+
+int fastlog2(uint64_t sz)
+{
+	int l = 0;
+	if (sz == 0)
+		return 0;
+	for (; sz; sz /= 2) {
+		l++;
+	}
+	return l - 1;
+}
+
+struct segment *sizes_to_segments(int *seglen, uint64_t *sizes, int n)
+{
+	struct segment *segs = reftable_calloc(sizeof(struct segment) * n);
+	int next = 0;
+	struct segment cur = { 0 };
+	int i = 0;
+
+	if (n == 0) {
+		*seglen = 0;
+		return segs;
+	}
+	for (i = 0; i < n; i++) {
+		int log = fastlog2(sizes[i]);
+		if (cur.log != log && cur.bytes > 0) {
+			struct segment fresh = {
+				.start = i,
+			};
+
+			segs[next++] = cur;
+			cur = fresh;
+		}
+
+		cur.log = log;
+		cur.end = i + 1;
+		cur.bytes += sizes[i];
+	}
+	segs[next++] = cur;
+	*seglen = next;
+	return segs;
+}
+
+struct segment suggest_compaction_segment(uint64_t *sizes, int n)
+{
+	int seglen = 0;
+	struct segment *segs = sizes_to_segments(&seglen, sizes, n);
+	struct segment min_seg = {
+		.log = 64,
+	};
+	int i = 0;
+	for (i = 0; i < seglen; i++) {
+		if (segment_size(&segs[i]) == 1) {
+			continue;
+		}
+
+		if (segs[i].log < min_seg.log) {
+			min_seg = segs[i];
+		}
+	}
+
+	while (min_seg.start > 0) {
+		int prev = min_seg.start - 1;
+		if (fastlog2(min_seg.bytes) < fastlog2(sizes[prev])) {
+			break;
+		}
+
+		min_seg.start = prev;
+		min_seg.bytes += sizes[prev];
+	}
+
+	reftable_free(segs);
+	return min_seg;
+}
+
+static uint64_t *stack_table_sizes_for_compaction(struct reftable_stack *st)
+{
+	uint64_t *sizes =
+		reftable_calloc(sizeof(uint64_t) * st->merged->stack_len);
+	int version = (st->config.hash_id == GIT_SHA1_FORMAT_ID) ? 1 : 2;
+	int overhead = header_size(version) - 1;
+	int i = 0;
+	for (i = 0; i < st->merged->stack_len; i++) {
+		sizes[i] = st->readers[i]->size - overhead;
+	}
+	return sizes;
+}
+
+int reftable_stack_auto_compact(struct reftable_stack *st)
+{
+	uint64_t *sizes = stack_table_sizes_for_compaction(st);
+	struct segment seg =
+		suggest_compaction_segment(sizes, st->merged->stack_len);
+	reftable_free(sizes);
+	if (segment_size(&seg) > 0)
+		return stack_compact_range_stats(st, seg.start, seg.end - 1,
+						 NULL);
+
+	return 0;
+}
+
+struct reftable_compaction_stats *
+reftable_stack_compaction_stats(struct reftable_stack *st)
+{
+	return &st->stats;
+}
+
+int reftable_stack_read_ref(struct reftable_stack *st, const char *refname,
+			    struct reftable_ref_record *ref)
+{
+	struct reftable_table tab = { NULL };
+	reftable_table_from_merged_table(&tab, reftable_stack_merged_table(st));
+	return reftable_table_read_ref(&tab, refname, ref);
+}
+
+int reftable_stack_read_log(struct reftable_stack *st, const char *refname,
+			    struct reftable_log_record *log)
+{
+	struct reftable_iterator it = { NULL };
+	struct reftable_merged_table *mt = reftable_stack_merged_table(st);
+	int err = reftable_merged_table_seek_log(mt, &it, refname);
+	if (err)
+		goto done;
+
+	err = reftable_iterator_next_log(&it, log);
+	if (err)
+		goto done;
+
+	if (strcmp(log->refname, refname) ||
+	    reftable_log_record_is_deletion(log)) {
+		err = 1;
+		goto done;
+	}
+
+done:
+	if (err) {
+		reftable_log_record_release(log);
+	}
+	reftable_iterator_destroy(&it);
+	return err;
+}
+
+static int stack_check_addition(struct reftable_stack *st,
+				const char *new_tab_name)
+{
+	int err = 0;
+	struct reftable_block_source src = { NULL };
+	struct reftable_reader *rd = NULL;
+	struct reftable_table tab = { NULL };
+	struct reftable_ref_record *refs = NULL;
+	struct reftable_iterator it = { NULL };
+	int cap = 0;
+	int len = 0;
+	int i = 0;
+
+	if (st->config.skip_name_check)
+		return 0;
+
+	err = reftable_block_source_from_file(&src, new_tab_name);
+	if (err < 0)
+		goto done;
+
+	err = reftable_new_reader(&rd, &src, new_tab_name);
+	if (err < 0)
+		goto done;
+
+	err = reftable_reader_seek_ref(rd, &it, "");
+	if (err > 0) {
+		err = 0;
+		goto done;
+	}
+	if (err < 0)
+		goto done;
+
+	while (1) {
+		struct reftable_ref_record ref = { NULL };
+		err = reftable_iterator_next_ref(&it, &ref);
+		if (err > 0) {
+			break;
+		}
+		if (err < 0)
+			goto done;
+
+		if (len >= cap) {
+			cap = 2 * cap + 1;
+			refs = reftable_realloc(refs, cap * sizeof(refs[0]));
+		}
+
+		refs[len++] = ref;
+	}
+
+	reftable_table_from_merged_table(&tab, reftable_stack_merged_table(st));
+
+	err = validate_ref_record_addition(tab, refs, len);
+
+done:
+	for (i = 0; i < len; i++) {
+		reftable_ref_record_release(&refs[i]);
+	}
+
+	free(refs);
+	reftable_iterator_destroy(&it);
+	reftable_reader_free(rd);
+	return err;
+}
+
+static int is_table_name(const char *s)
+{
+	const char *dot = strrchr(s, '.');
+	return dot && !strcmp(dot, ".ref");
+}
+
+static void remove_maybe_stale_table(struct reftable_stack *st, uint64_t max,
+				     const char *name)
+{
+	int err = 0;
+	uint64_t update_idx = 0;
+	struct reftable_block_source src = { NULL };
+	struct reftable_reader *rd = NULL;
+	struct strbuf table_path = STRBUF_INIT;
+	stack_filename(&table_path, st, name);
+
+	err = reftable_block_source_from_file(&src, table_path.buf);
+	if (err < 0)
+		goto done;
+
+	err = reftable_new_reader(&rd, &src, name);
+	if (err < 0)
+		goto done;
+
+	update_idx = reftable_reader_max_update_index(rd);
+	reftable_reader_free(rd);
+
+	if (update_idx <= max) {
+		unlink(table_path.buf);
+	}
+done:
+	strbuf_release(&table_path);
+}
+
+static int reftable_stack_clean_locked(struct reftable_stack *st)
+{
+	uint64_t max = reftable_merged_table_max_update_index(
+		reftable_stack_merged_table(st));
+	DIR *dir = opendir(st->reftable_dir);
+	struct dirent *d = NULL;
+	if (!dir) {
+		return REFTABLE_IO_ERROR;
+	}
+
+	while ((d = readdir(dir))) {
+		int i = 0;
+		int found = 0;
+		if (!is_table_name(d->d_name))
+			continue;
+
+		for (i = 0; !found && i < st->readers_len; i++) {
+			found = !strcmp(reader_name(st->readers[i]), d->d_name);
+		}
+		if (found)
+			continue;
+
+		remove_maybe_stale_table(st, max, d->d_name);
+	}
+
+	closedir(dir);
+	return 0;
+}
+
+int reftable_stack_clean(struct reftable_stack *st)
+{
+	struct reftable_addition *add = NULL;
+	int err = reftable_stack_new_addition(&add, st);
+	if (err < 0) {
+		goto done;
+	}
+
+	err = reftable_stack_reload(st);
+	if (err < 0) {
+		goto done;
+	}
+
+	err = reftable_stack_clean_locked(st);
+
+done:
+	reftable_addition_destroy(add);
+	return err;
+}
+
+int reftable_stack_print_directory(const char *stackdir, uint32_t hash_id)
+{
+	struct reftable_stack *stack = NULL;
+	struct reftable_write_options cfg = { .hash_id = hash_id };
+	struct reftable_merged_table *merged = NULL;
+	struct reftable_table table = { NULL };
+
+	int err = reftable_new_stack(&stack, stackdir, cfg);
+	if (err < 0)
+		goto done;
+
+	merged = reftable_stack_merged_table(stack);
+	reftable_table_from_merged_table(&table, merged);
+	err = reftable_table_print(&table);
+done:
+	if (stack)
+		reftable_stack_destroy(stack);
+	return err;
+}
diff --git a/reftable/stack.h b/reftable/stack.h
new file mode 100644
index 0000000..f570058
--- /dev/null
+++ b/reftable/stack.h
@@ -0,0 +1,41 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef STACK_H
+#define STACK_H
+
+#include "system.h"
+#include "reftable-writer.h"
+#include "reftable-stack.h"
+
+struct reftable_stack {
+	char *list_file;
+	char *reftable_dir;
+	int disable_auto_compact;
+
+	struct reftable_write_options config;
+
+	struct reftable_reader **readers;
+	size_t readers_len;
+	struct reftable_merged_table *merged;
+	struct reftable_compaction_stats stats;
+};
+
+int read_lines(const char *filename, char ***lines);
+
+struct segment {
+	int start, end;
+	int log;
+	uint64_t bytes;
+};
+
+int fastlog2(uint64_t sz);
+struct segment *sizes_to_segments(int *seglen, uint64_t *sizes, int n);
+struct segment suggest_compaction_segment(uint64_t *sizes, int n);
+
+#endif
diff --git a/reftable/stack_test.c b/reftable/stack_test.c
new file mode 100644
index 0000000..f4c743d
--- /dev/null
+++ b/reftable/stack_test.c
@@ -0,0 +1,978 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "stack.h"
+
+#include "system.h"
+
+#include "reftable-reader.h"
+#include "merged.h"
+#include "basics.h"
+#include "constants.h"
+#include "record.h"
+#include "test_framework.h"
+#include "reftable-tests.h"
+#include "reader.h"
+
+#include <sys/types.h>
+#include <dirent.h>
+
+static void clear_dir(const char *dirname)
+{
+	struct strbuf path = STRBUF_INIT;
+	strbuf_addstr(&path, dirname);
+	remove_dir_recursively(&path, 0);
+	strbuf_release(&path);
+}
+
+static int count_dir_entries(const char *dirname)
+{
+	DIR *dir = opendir(dirname);
+	int len = 0;
+	struct dirent *d;
+	if (dir == NULL)
+		return 0;
+
+	while ((d = readdir(dir))) {
+		if (!strcmp(d->d_name, "..") || !strcmp(d->d_name, "."))
+			continue;
+		len++;
+	}
+	closedir(dir);
+	return len;
+}
+
+/*
+ * Work linenumber into the tempdir, so we can see which tests forget to
+ * cleanup.
+ */
+static char *get_tmp_template(int linenumber)
+{
+	const char *tmp = getenv("TMPDIR");
+	static char template[1024];
+	snprintf(template, sizeof(template) - 1, "%s/stack_test-%d.XXXXXX",
+		 tmp ? tmp : "/tmp", linenumber);
+	return template;
+}
+
+static char *get_tmp_dir(int linenumber)
+{
+	char *dir = get_tmp_template(linenumber);
+	EXPECT(mkdtemp(dir));
+	return dir;
+}
+
+static void test_read_file(void)
+{
+	char *fn = get_tmp_template(__LINE__);
+	int fd = mkstemp(fn);
+	char out[1024] = "line1\n\nline2\nline3";
+	int n, err;
+	char **names = NULL;
+	char *want[] = { "line1", "line2", "line3" };
+	int i = 0;
+
+	EXPECT(fd > 0);
+	n = write(fd, out, strlen(out));
+	EXPECT(n == strlen(out));
+	err = close(fd);
+	EXPECT(err >= 0);
+
+	err = read_lines(fn, &names);
+	EXPECT_ERR(err);
+
+	for (i = 0; names[i]; i++) {
+		EXPECT(0 == strcmp(want[i], names[i]));
+	}
+	free_names(names);
+	remove(fn);
+}
+
+static void test_parse_names(void)
+{
+	char buf[] = "line\n";
+	char **names = NULL;
+	parse_names(buf, strlen(buf), &names);
+
+	EXPECT(NULL != names[0]);
+	EXPECT(0 == strcmp(names[0], "line"));
+	EXPECT(NULL == names[1]);
+	free_names(names);
+}
+
+static void test_names_equal(void)
+{
+	char *a[] = { "a", "b", "c", NULL };
+	char *b[] = { "a", "b", "d", NULL };
+	char *c[] = { "a", "b", NULL };
+
+	EXPECT(names_equal(a, a));
+	EXPECT(!names_equal(a, b));
+	EXPECT(!names_equal(a, c));
+}
+
+static int write_test_ref(struct reftable_writer *wr, void *arg)
+{
+	struct reftable_ref_record *ref = arg;
+	reftable_writer_set_limits(wr, ref->update_index, ref->update_index);
+	return reftable_writer_add_ref(wr, ref);
+}
+
+struct write_log_arg {
+	struct reftable_log_record *log;
+	uint64_t update_index;
+};
+
+static int write_test_log(struct reftable_writer *wr, void *arg)
+{
+	struct write_log_arg *wla = arg;
+
+	reftable_writer_set_limits(wr, wla->update_index, wla->update_index);
+	return reftable_writer_add_log(wr, wla->log);
+}
+
+static void test_reftable_stack_add_one(void)
+{
+	char *dir = get_tmp_dir(__LINE__);
+	struct strbuf scratch = STRBUF_INIT;
+	int mask = umask(002);
+	struct reftable_write_options cfg = {
+		.default_permissions = 0660,
+	};
+	struct reftable_stack *st = NULL;
+	int err;
+	struct reftable_ref_record ref = {
+		.refname = "HEAD",
+		.update_index = 1,
+		.value_type = REFTABLE_REF_SYMREF,
+		.value.symref = "master",
+	};
+	struct reftable_ref_record dest = { NULL };
+	struct stat stat_result = { 0 };
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_add(st, &write_test_ref, &ref);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_read_ref(st, ref.refname, &dest);
+	EXPECT_ERR(err);
+	EXPECT(0 == strcmp("master", dest.value.symref));
+	EXPECT(st->readers_len > 0);
+
+	printf("testing print functionality:\n");
+	err = reftable_stack_print_directory(dir, GIT_SHA1_FORMAT_ID);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_print_directory(dir, GIT_SHA256_FORMAT_ID);
+	EXPECT(err == REFTABLE_FORMAT_ERROR);
+
+#ifndef GIT_WINDOWS_NATIVE
+	strbuf_addstr(&scratch, dir);
+	strbuf_addstr(&scratch, "/tables.list");
+	err = stat(scratch.buf, &stat_result);
+	EXPECT(!err);
+	EXPECT((stat_result.st_mode & 0777) == cfg.default_permissions);
+
+	strbuf_reset(&scratch);
+	strbuf_addstr(&scratch, dir);
+	strbuf_addstr(&scratch, "/");
+	/* do not try at home; not an external API for reftable. */
+	strbuf_addstr(&scratch, st->readers[0]->name);
+	err = stat(scratch.buf, &stat_result);
+	EXPECT(!err);
+	EXPECT((stat_result.st_mode & 0777) == cfg.default_permissions);
+#else
+	(void) stat_result;
+#endif
+
+	reftable_ref_record_release(&dest);
+	reftable_stack_destroy(st);
+	strbuf_release(&scratch);
+	clear_dir(dir);
+	umask(mask);
+}
+
+static void test_reftable_stack_uptodate(void)
+{
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st1 = NULL;
+	struct reftable_stack *st2 = NULL;
+	char *dir = get_tmp_dir(__LINE__);
+
+	int err;
+	struct reftable_ref_record ref1 = {
+		.refname = "HEAD",
+		.update_index = 1,
+		.value_type = REFTABLE_REF_SYMREF,
+		.value.symref = "master",
+	};
+	struct reftable_ref_record ref2 = {
+		.refname = "branch2",
+		.update_index = 2,
+		.value_type = REFTABLE_REF_SYMREF,
+		.value.symref = "master",
+	};
+
+
+	/* simulate multi-process access to the same stack
+	   by creating two stacks for the same directory.
+	 */
+	err = reftable_new_stack(&st1, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_new_stack(&st2, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_add(st1, &write_test_ref, &ref1);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_add(st2, &write_test_ref, &ref2);
+	EXPECT(err == REFTABLE_LOCK_ERROR);
+
+	err = reftable_stack_reload(st2);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_add(st2, &write_test_ref, &ref2);
+	EXPECT_ERR(err);
+	reftable_stack_destroy(st1);
+	reftable_stack_destroy(st2);
+	clear_dir(dir);
+}
+
+static void test_reftable_stack_transaction_api(void)
+{
+	char *dir = get_tmp_dir(__LINE__);
+
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st = NULL;
+	int err;
+	struct reftable_addition *add = NULL;
+
+	struct reftable_ref_record ref = {
+		.refname = "HEAD",
+		.update_index = 1,
+		.value_type = REFTABLE_REF_SYMREF,
+		.value.symref = "master",
+	};
+	struct reftable_ref_record dest = { NULL };
+
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	reftable_addition_destroy(add);
+
+	err = reftable_stack_new_addition(&add, st);
+	EXPECT_ERR(err);
+
+	err = reftable_addition_add(add, &write_test_ref, &ref);
+	EXPECT_ERR(err);
+
+	err = reftable_addition_commit(add);
+	EXPECT_ERR(err);
+
+	reftable_addition_destroy(add);
+
+	err = reftable_stack_read_ref(st, ref.refname, &dest);
+	EXPECT_ERR(err);
+	EXPECT(REFTABLE_REF_SYMREF == dest.value_type);
+	EXPECT(0 == strcmp("master", dest.value.symref));
+
+	reftable_ref_record_release(&dest);
+	reftable_stack_destroy(st);
+	clear_dir(dir);
+}
+
+static void test_reftable_stack_validate_refname(void)
+{
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st = NULL;
+	int err;
+	char *dir = get_tmp_dir(__LINE__);
+
+	int i;
+	struct reftable_ref_record ref = {
+		.refname = "a/b",
+		.update_index = 1,
+		.value_type = REFTABLE_REF_SYMREF,
+		.value.symref = "master",
+	};
+	char *additions[] = { "a", "a/b/c" };
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_add(st, &write_test_ref, &ref);
+	EXPECT_ERR(err);
+
+	for (i = 0; i < ARRAY_SIZE(additions); i++) {
+		struct reftable_ref_record ref = {
+			.refname = additions[i],
+			.update_index = 1,
+			.value_type = REFTABLE_REF_SYMREF,
+			.value.symref = "master",
+		};
+
+		err = reftable_stack_add(st, &write_test_ref, &ref);
+		EXPECT(err == REFTABLE_NAME_CONFLICT);
+	}
+
+	reftable_stack_destroy(st);
+	clear_dir(dir);
+}
+
+static int write_error(struct reftable_writer *wr, void *arg)
+{
+	return *((int *)arg);
+}
+
+static void test_reftable_stack_update_index_check(void)
+{
+	char *dir = get_tmp_dir(__LINE__);
+
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st = NULL;
+	int err;
+	struct reftable_ref_record ref1 = {
+		.refname = "name1",
+		.update_index = 1,
+		.value_type = REFTABLE_REF_SYMREF,
+		.value.symref = "master",
+	};
+	struct reftable_ref_record ref2 = {
+		.refname = "name2",
+		.update_index = 1,
+		.value_type = REFTABLE_REF_SYMREF,
+		.value.symref = "master",
+	};
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_add(st, &write_test_ref, &ref1);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_add(st, &write_test_ref, &ref2);
+	EXPECT(err == REFTABLE_API_ERROR);
+	reftable_stack_destroy(st);
+	clear_dir(dir);
+}
+
+static void test_reftable_stack_lock_failure(void)
+{
+	char *dir = get_tmp_dir(__LINE__);
+
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st = NULL;
+	int err, i;
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+	for (i = -1; i != REFTABLE_EMPTY_TABLE_ERROR; i--) {
+		err = reftable_stack_add(st, &write_error, &i);
+		EXPECT(err == i);
+	}
+
+	reftable_stack_destroy(st);
+	clear_dir(dir);
+}
+
+static void test_reftable_stack_add(void)
+{
+	int i = 0;
+	int err = 0;
+	struct reftable_write_options cfg = {
+		.exact_log_message = 1,
+	};
+	struct reftable_stack *st = NULL;
+	char *dir = get_tmp_dir(__LINE__);
+
+	struct reftable_ref_record refs[2] = { { NULL } };
+	struct reftable_log_record logs[2] = { { NULL } };
+	int N = ARRAY_SIZE(refs);
+
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+	st->disable_auto_compact = 1;
+
+	for (i = 0; i < N; i++) {
+		char buf[256];
+		snprintf(buf, sizeof(buf), "branch%02d", i);
+		refs[i].refname = xstrdup(buf);
+		refs[i].update_index = i + 1;
+		refs[i].value_type = REFTABLE_REF_VAL1;
+		refs[i].value.val1 = reftable_malloc(GIT_SHA1_RAWSZ);
+		set_test_hash(refs[i].value.val1, i);
+
+		logs[i].refname = xstrdup(buf);
+		logs[i].update_index = N + i + 1;
+		logs[i].value_type = REFTABLE_LOG_UPDATE;
+
+		logs[i].value.update.new_hash = reftable_malloc(GIT_SHA1_RAWSZ);
+		logs[i].value.update.email = xstrdup("identity@invalid");
+		set_test_hash(logs[i].value.update.new_hash, i);
+	}
+
+	for (i = 0; i < N; i++) {
+		int err = reftable_stack_add(st, &write_test_ref, &refs[i]);
+		EXPECT_ERR(err);
+	}
+
+	for (i = 0; i < N; i++) {
+		struct write_log_arg arg = {
+			.log = &logs[i],
+			.update_index = reftable_stack_next_update_index(st),
+		};
+		int err = reftable_stack_add(st, &write_test_log, &arg);
+		EXPECT_ERR(err);
+	}
+
+	err = reftable_stack_compact_all(st, NULL);
+	EXPECT_ERR(err);
+
+	for (i = 0; i < N; i++) {
+		struct reftable_ref_record dest = { NULL };
+
+		int err = reftable_stack_read_ref(st, refs[i].refname, &dest);
+		EXPECT_ERR(err);
+		EXPECT(reftable_ref_record_equal(&dest, refs + i,
+						 GIT_SHA1_RAWSZ));
+		reftable_ref_record_release(&dest);
+	}
+
+	for (i = 0; i < N; i++) {
+		struct reftable_log_record dest = { NULL };
+		int err = reftable_stack_read_log(st, refs[i].refname, &dest);
+		EXPECT_ERR(err);
+		EXPECT(reftable_log_record_equal(&dest, logs + i,
+						 GIT_SHA1_RAWSZ));
+		reftable_log_record_release(&dest);
+	}
+
+	/* cleanup */
+	reftable_stack_destroy(st);
+	for (i = 0; i < N; i++) {
+		reftable_ref_record_release(&refs[i]);
+		reftable_log_record_release(&logs[i]);
+	}
+	clear_dir(dir);
+}
+
+static void test_reftable_stack_log_normalize(void)
+{
+	int err = 0;
+	struct reftable_write_options cfg = {
+		0,
+	};
+	struct reftable_stack *st = NULL;
+	char *dir = get_tmp_dir(__LINE__);
+
+	uint8_t h1[GIT_SHA1_RAWSZ] = { 0x01 }, h2[GIT_SHA1_RAWSZ] = { 0x02 };
+
+	struct reftable_log_record input = { .refname = "branch",
+					     .update_index = 1,
+					     .value_type = REFTABLE_LOG_UPDATE,
+					     .value = { .update = {
+								.new_hash = h1,
+								.old_hash = h2,
+							} } };
+	struct reftable_log_record dest = {
+		.update_index = 0,
+	};
+	struct write_log_arg arg = {
+		.log = &input,
+		.update_index = 1,
+	};
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	input.value.update.message = "one\ntwo";
+	err = reftable_stack_add(st, &write_test_log, &arg);
+	EXPECT(err == REFTABLE_API_ERROR);
+
+	input.value.update.message = "one";
+	err = reftable_stack_add(st, &write_test_log, &arg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_read_log(st, input.refname, &dest);
+	EXPECT_ERR(err);
+	EXPECT(0 == strcmp(dest.value.update.message, "one\n"));
+
+	input.value.update.message = "two\n";
+	arg.update_index = 2;
+	err = reftable_stack_add(st, &write_test_log, &arg);
+	EXPECT_ERR(err);
+	err = reftable_stack_read_log(st, input.refname, &dest);
+	EXPECT_ERR(err);
+	EXPECT(0 == strcmp(dest.value.update.message, "two\n"));
+
+	/* cleanup */
+	reftable_stack_destroy(st);
+	reftable_log_record_release(&dest);
+	clear_dir(dir);
+}
+
+static void test_reftable_stack_tombstone(void)
+{
+	int i = 0;
+	char *dir = get_tmp_dir(__LINE__);
+
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st = NULL;
+	int err;
+	struct reftable_ref_record refs[2] = { { NULL } };
+	struct reftable_log_record logs[2] = { { NULL } };
+	int N = ARRAY_SIZE(refs);
+	struct reftable_ref_record dest = { NULL };
+	struct reftable_log_record log_dest = { NULL };
+
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	/* even entries add the refs, odd entries delete them. */
+	for (i = 0; i < N; i++) {
+		const char *buf = "branch";
+		refs[i].refname = xstrdup(buf);
+		refs[i].update_index = i + 1;
+		if (i % 2 == 0) {
+			refs[i].value_type = REFTABLE_REF_VAL1;
+			refs[i].value.val1 = reftable_malloc(GIT_SHA1_RAWSZ);
+			set_test_hash(refs[i].value.val1, i);
+		}
+
+		logs[i].refname = xstrdup(buf);
+		/* update_index is part of the key. */
+		logs[i].update_index = 42;
+		if (i % 2 == 0) {
+			logs[i].value_type = REFTABLE_LOG_UPDATE;
+			logs[i].value.update.new_hash =
+				reftable_malloc(GIT_SHA1_RAWSZ);
+			set_test_hash(logs[i].value.update.new_hash, i);
+			logs[i].value.update.email =
+				xstrdup("identity@invalid");
+		}
+	}
+	for (i = 0; i < N; i++) {
+		int err = reftable_stack_add(st, &write_test_ref, &refs[i]);
+		EXPECT_ERR(err);
+	}
+
+	for (i = 0; i < N; i++) {
+		struct write_log_arg arg = {
+			.log = &logs[i],
+			.update_index = reftable_stack_next_update_index(st),
+		};
+		int err = reftable_stack_add(st, &write_test_log, &arg);
+		EXPECT_ERR(err);
+	}
+
+	err = reftable_stack_read_ref(st, "branch", &dest);
+	EXPECT(err == 1);
+	reftable_ref_record_release(&dest);
+
+	err = reftable_stack_read_log(st, "branch", &log_dest);
+	EXPECT(err == 1);
+	reftable_log_record_release(&log_dest);
+
+	err = reftable_stack_compact_all(st, NULL);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_read_ref(st, "branch", &dest);
+	EXPECT(err == 1);
+
+	err = reftable_stack_read_log(st, "branch", &log_dest);
+	EXPECT(err == 1);
+	reftable_ref_record_release(&dest);
+	reftable_log_record_release(&log_dest);
+
+	/* cleanup */
+	reftable_stack_destroy(st);
+	for (i = 0; i < N; i++) {
+		reftable_ref_record_release(&refs[i]);
+		reftable_log_record_release(&logs[i]);
+	}
+	clear_dir(dir);
+}
+
+static void test_reftable_stack_hash_id(void)
+{
+	char *dir = get_tmp_dir(__LINE__);
+
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st = NULL;
+	int err;
+
+	struct reftable_ref_record ref = {
+		.refname = "master",
+		.value_type = REFTABLE_REF_SYMREF,
+		.value.symref = "target",
+		.update_index = 1,
+	};
+	struct reftable_write_options cfg32 = { .hash_id = GIT_SHA256_FORMAT_ID };
+	struct reftable_stack *st32 = NULL;
+	struct reftable_write_options cfg_default = { 0 };
+	struct reftable_stack *st_default = NULL;
+	struct reftable_ref_record dest = { NULL };
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_add(st, &write_test_ref, &ref);
+	EXPECT_ERR(err);
+
+	/* can't read it with the wrong hash ID. */
+	err = reftable_new_stack(&st32, dir, cfg32);
+	EXPECT(err == REFTABLE_FORMAT_ERROR);
+
+	/* check that we can read it back with default config too. */
+	err = reftable_new_stack(&st_default, dir, cfg_default);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_read_ref(st_default, "master", &dest);
+	EXPECT_ERR(err);
+
+	EXPECT(reftable_ref_record_equal(&ref, &dest, GIT_SHA1_RAWSZ));
+	reftable_ref_record_release(&dest);
+	reftable_stack_destroy(st);
+	reftable_stack_destroy(st_default);
+	clear_dir(dir);
+}
+
+static void test_log2(void)
+{
+	EXPECT(1 == fastlog2(3));
+	EXPECT(2 == fastlog2(4));
+	EXPECT(2 == fastlog2(5));
+}
+
+static void test_sizes_to_segments(void)
+{
+	uint64_t sizes[] = { 2, 3, 4, 5, 7, 9 };
+	/* .................0  1  2  3  4  5 */
+
+	int seglen = 0;
+	struct segment *segs =
+		sizes_to_segments(&seglen, sizes, ARRAY_SIZE(sizes));
+	EXPECT(segs[2].log == 3);
+	EXPECT(segs[2].start == 5);
+	EXPECT(segs[2].end == 6);
+
+	EXPECT(segs[1].log == 2);
+	EXPECT(segs[1].start == 2);
+	EXPECT(segs[1].end == 5);
+	reftable_free(segs);
+}
+
+static void test_sizes_to_segments_empty(void)
+{
+	int seglen = 0;
+	struct segment *segs = sizes_to_segments(&seglen, NULL, 0);
+	EXPECT(seglen == 0);
+	reftable_free(segs);
+}
+
+static void test_sizes_to_segments_all_equal(void)
+{
+	uint64_t sizes[] = { 5, 5 };
+
+	int seglen = 0;
+	struct segment *segs =
+		sizes_to_segments(&seglen, sizes, ARRAY_SIZE(sizes));
+	EXPECT(seglen == 1);
+	EXPECT(segs[0].start == 0);
+	EXPECT(segs[0].end == 2);
+	reftable_free(segs);
+}
+
+static void test_suggest_compaction_segment(void)
+{
+	uint64_t sizes[] = { 128, 64, 17, 16, 9, 9, 9, 16, 16 };
+	/* .................0    1    2  3   4  5  6 */
+	struct segment min =
+		suggest_compaction_segment(sizes, ARRAY_SIZE(sizes));
+	EXPECT(min.start == 2);
+	EXPECT(min.end == 7);
+}
+
+static void test_suggest_compaction_segment_nothing(void)
+{
+	uint64_t sizes[] = { 64, 32, 16, 8, 4, 2 };
+	struct segment result =
+		suggest_compaction_segment(sizes, ARRAY_SIZE(sizes));
+	EXPECT(result.start == result.end);
+}
+
+static void test_reflog_expire(void)
+{
+	char *dir = get_tmp_dir(__LINE__);
+
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st = NULL;
+	struct reftable_log_record logs[20] = { { NULL } };
+	int N = ARRAY_SIZE(logs) - 1;
+	int i = 0;
+	int err;
+	struct reftable_log_expiry_config expiry = {
+		.time = 10,
+	};
+	struct reftable_log_record log = { NULL };
+
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	for (i = 1; i <= N; i++) {
+		char buf[256];
+		snprintf(buf, sizeof(buf), "branch%02d", i);
+
+		logs[i].refname = xstrdup(buf);
+		logs[i].update_index = i;
+		logs[i].value_type = REFTABLE_LOG_UPDATE;
+		logs[i].value.update.time = i;
+		logs[i].value.update.new_hash = reftable_malloc(GIT_SHA1_RAWSZ);
+		logs[i].value.update.email = xstrdup("identity@invalid");
+		set_test_hash(logs[i].value.update.new_hash, i);
+	}
+
+	for (i = 1; i <= N; i++) {
+		struct write_log_arg arg = {
+			.log = &logs[i],
+			.update_index = reftable_stack_next_update_index(st),
+		};
+		int err = reftable_stack_add(st, &write_test_log, &arg);
+		EXPECT_ERR(err);
+	}
+
+	err = reftable_stack_compact_all(st, NULL);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_compact_all(st, &expiry);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_read_log(st, logs[9].refname, &log);
+	EXPECT(err == 1);
+
+	err = reftable_stack_read_log(st, logs[11].refname, &log);
+	EXPECT_ERR(err);
+
+	expiry.min_update_index = 15;
+	err = reftable_stack_compact_all(st, &expiry);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_read_log(st, logs[14].refname, &log);
+	EXPECT(err == 1);
+
+	err = reftable_stack_read_log(st, logs[16].refname, &log);
+	EXPECT_ERR(err);
+
+	/* cleanup */
+	reftable_stack_destroy(st);
+	for (i = 0; i <= N; i++) {
+		reftable_log_record_release(&logs[i]);
+	}
+	clear_dir(dir);
+	reftable_log_record_release(&log);
+}
+
+static int write_nothing(struct reftable_writer *wr, void *arg)
+{
+	reftable_writer_set_limits(wr, 1, 1);
+	return 0;
+}
+
+static void test_empty_add(void)
+{
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st = NULL;
+	int err;
+	char *dir = get_tmp_dir(__LINE__);
+
+	struct reftable_stack *st2 = NULL;
+
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_add(st, &write_nothing, NULL);
+	EXPECT_ERR(err);
+
+	err = reftable_new_stack(&st2, dir, cfg);
+	EXPECT_ERR(err);
+	clear_dir(dir);
+	reftable_stack_destroy(st);
+	reftable_stack_destroy(st2);
+}
+
+static void test_reftable_stack_auto_compaction(void)
+{
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st = NULL;
+	char *dir = get_tmp_dir(__LINE__);
+
+	int err, i;
+	int N = 100;
+
+	err = reftable_new_stack(&st, dir, cfg);
+	EXPECT_ERR(err);
+
+	st->disable_auto_compact = 1; /* call manually below for coverage. */
+	for (i = 0; i < N; i++) {
+		char name[100];
+		struct reftable_ref_record ref = {
+			.refname = name,
+			.update_index = reftable_stack_next_update_index(st),
+			.value_type = REFTABLE_REF_SYMREF,
+			.value.symref = "master",
+		};
+		snprintf(name, sizeof(name), "branch%04d", i);
+
+		err = reftable_stack_add(st, &write_test_ref, &ref);
+		EXPECT_ERR(err);
+
+		err = reftable_stack_auto_compact(st);
+		EXPECT(i < 3 || st->merged->stack_len < 2 * fastlog2(i));
+	}
+
+	EXPECT(reftable_stack_compaction_stats(st)->entries_written <
+	       (uint64_t)(N * fastlog2(N)));
+
+	reftable_stack_destroy(st);
+	clear_dir(dir);
+}
+
+static void test_reftable_stack_compaction_concurrent(void)
+{
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st1 = NULL, *st2 = NULL;
+	char *dir = get_tmp_dir(__LINE__);
+
+	int err, i;
+	int N = 3;
+
+	err = reftable_new_stack(&st1, dir, cfg);
+	EXPECT_ERR(err);
+
+	for (i = 0; i < N; i++) {
+		char name[100];
+		struct reftable_ref_record ref = {
+			.refname = name,
+			.update_index = reftable_stack_next_update_index(st1),
+			.value_type = REFTABLE_REF_SYMREF,
+			.value.symref = "master",
+		};
+		snprintf(name, sizeof(name), "branch%04d", i);
+
+		err = reftable_stack_add(st1, &write_test_ref, &ref);
+		EXPECT_ERR(err);
+	}
+
+	err = reftable_new_stack(&st2, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_compact_all(st1, NULL);
+	EXPECT_ERR(err);
+
+	reftable_stack_destroy(st1);
+	reftable_stack_destroy(st2);
+
+	EXPECT(count_dir_entries(dir) == 2);
+	clear_dir(dir);
+}
+
+static void unclean_stack_close(struct reftable_stack *st)
+{
+	/* break abstraction boundary to simulate unclean shutdown. */
+	int i = 0;
+	for (; i < st->readers_len; i++) {
+		reftable_reader_free(st->readers[i]);
+	}
+	st->readers_len = 0;
+	FREE_AND_NULL(st->readers);
+}
+
+static void test_reftable_stack_compaction_concurrent_clean(void)
+{
+	struct reftable_write_options cfg = { 0 };
+	struct reftable_stack *st1 = NULL, *st2 = NULL, *st3 = NULL;
+	char *dir = get_tmp_dir(__LINE__);
+
+	int err, i;
+	int N = 3;
+
+	err = reftable_new_stack(&st1, dir, cfg);
+	EXPECT_ERR(err);
+
+	for (i = 0; i < N; i++) {
+		char name[100];
+		struct reftable_ref_record ref = {
+			.refname = name,
+			.update_index = reftable_stack_next_update_index(st1),
+			.value_type = REFTABLE_REF_SYMREF,
+			.value.symref = "master",
+		};
+		snprintf(name, sizeof(name), "branch%04d", i);
+
+		err = reftable_stack_add(st1, &write_test_ref, &ref);
+		EXPECT_ERR(err);
+	}
+
+	err = reftable_new_stack(&st2, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_compact_all(st1, NULL);
+	EXPECT_ERR(err);
+
+	unclean_stack_close(st1);
+	unclean_stack_close(st2);
+
+	err = reftable_new_stack(&st3, dir, cfg);
+	EXPECT_ERR(err);
+
+	err = reftable_stack_clean(st3);
+	EXPECT_ERR(err);
+	EXPECT(count_dir_entries(dir) == 2);
+
+	reftable_stack_destroy(st1);
+	reftable_stack_destroy(st2);
+	reftable_stack_destroy(st3);
+
+	clear_dir(dir);
+}
+
+int stack_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_empty_add);
+	RUN_TEST(test_log2);
+	RUN_TEST(test_names_equal);
+	RUN_TEST(test_parse_names);
+	RUN_TEST(test_read_file);
+	RUN_TEST(test_reflog_expire);
+	RUN_TEST(test_reftable_stack_add);
+	RUN_TEST(test_reftable_stack_add_one);
+	RUN_TEST(test_reftable_stack_auto_compaction);
+	RUN_TEST(test_reftable_stack_compaction_concurrent);
+	RUN_TEST(test_reftable_stack_compaction_concurrent_clean);
+	RUN_TEST(test_reftable_stack_hash_id);
+	RUN_TEST(test_reftable_stack_lock_failure);
+	RUN_TEST(test_reftable_stack_log_normalize);
+	RUN_TEST(test_reftable_stack_tombstone);
+	RUN_TEST(test_reftable_stack_transaction_api);
+	RUN_TEST(test_reftable_stack_update_index_check);
+	RUN_TEST(test_reftable_stack_uptodate);
+	RUN_TEST(test_reftable_stack_validate_refname);
+	RUN_TEST(test_sizes_to_segments);
+	RUN_TEST(test_sizes_to_segments_all_equal);
+	RUN_TEST(test_sizes_to_segments_empty);
+	RUN_TEST(test_suggest_compaction_segment);
+	RUN_TEST(test_suggest_compaction_segment_nothing);
+	return 0;
+}
diff --git a/reftable/system.h b/reftable/system.h
new file mode 100644
index 0000000..4907306
--- /dev/null
+++ b/reftable/system.h
@@ -0,0 +1,32 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef SYSTEM_H
+#define SYSTEM_H
+
+/* This header glues the reftable library to the rest of Git */
+
+#include "git-compat-util.h"
+#include "strbuf.h"
+#include "hash.h" /* hash ID, sizes.*/
+#include "dir.h" /* remove_dir_recursively, for tests.*/
+
+#include <zlib.h>
+
+#ifdef NO_UNCOMPRESS2
+/*
+ * This is uncompress2, which is only available in zlib >= 1.2.9
+ * (released as of early 2017)
+ */
+int uncompress2(Bytef *dest, uLongf *destLen, const Bytef *source,
+		uLong *sourceLen);
+#endif
+
+int hash_size(uint32_t id);
+
+#endif
diff --git a/reftable/test_framework.c b/reftable/test_framework.c
new file mode 100644
index 0000000..84ac972
--- /dev/null
+++ b/reftable/test_framework.c
@@ -0,0 +1,23 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "system.h"
+#include "test_framework.h"
+
+#include "basics.h"
+
+void set_test_hash(uint8_t *p, int i)
+{
+	memset(p, (uint8_t)i, hash_size(GIT_SHA1_FORMAT_ID));
+}
+
+ssize_t strbuf_add_void(void *b, const void *data, size_t sz)
+{
+	strbuf_add(b, data, sz);
+	return sz;
+}
diff --git a/reftable/test_framework.h b/reftable/test_framework.h
new file mode 100644
index 0000000..774cb27
--- /dev/null
+++ b/reftable/test_framework.h
@@ -0,0 +1,53 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef TEST_FRAMEWORK_H
+#define TEST_FRAMEWORK_H
+
+#include "system.h"
+#include "reftable-error.h"
+
+#define EXPECT_ERR(c)                                                  \
+	if (c != 0) {                                                  \
+		fflush(stderr);                                        \
+		fflush(stdout);                                        \
+		fprintf(stderr, "%s: %d: error == %d (%s), want 0\n",  \
+			__FILE__, __LINE__, c, reftable_error_str(c)); \
+		abort();                                               \
+	}
+
+#define EXPECT_STREQ(a, b)                                               \
+	if (strcmp(a, b)) {                                              \
+		fflush(stderr);                                          \
+		fflush(stdout);                                          \
+		fprintf(stderr, "%s:%d: %s (%s) != %s (%s)\n", __FILE__, \
+			__LINE__, #a, a, #b, b);                         \
+		abort();                                                 \
+	}
+
+#define EXPECT(c)                                                          \
+	if (!(c)) {                                                        \
+		fflush(stderr);                                            \
+		fflush(stdout);                                            \
+		fprintf(stderr, "%s: %d: failed assertion %s\n", __FILE__, \
+			__LINE__, #c);                                     \
+		abort();                                                   \
+	}
+
+#define RUN_TEST(f)                          \
+	fprintf(stderr, "running %s\n", #f); \
+	fflush(stderr);                      \
+	f();
+
+void set_test_hash(uint8_t *p, int i);
+
+/* Like strbuf_add, but suitable for passing to reftable_new_writer
+ */
+ssize_t strbuf_add_void(void *b, const void *data, size_t sz);
+
+#endif
diff --git a/reftable/tree.c b/reftable/tree.c
new file mode 100644
index 0000000..82db799
--- /dev/null
+++ b/reftable/tree.c
@@ -0,0 +1,63 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "tree.h"
+
+#include "basics.h"
+#include "system.h"
+
+struct tree_node *tree_search(void *key, struct tree_node **rootp,
+			      int (*compare)(const void *, const void *),
+			      int insert)
+{
+	int res;
+	if (*rootp == NULL) {
+		if (!insert) {
+			return NULL;
+		} else {
+			struct tree_node *n =
+				reftable_calloc(sizeof(struct tree_node));
+			n->key = key;
+			*rootp = n;
+			return *rootp;
+		}
+	}
+
+	res = compare(key, (*rootp)->key);
+	if (res < 0)
+		return tree_search(key, &(*rootp)->left, compare, insert);
+	else if (res > 0)
+		return tree_search(key, &(*rootp)->right, compare, insert);
+	return *rootp;
+}
+
+void infix_walk(struct tree_node *t, void (*action)(void *arg, void *key),
+		void *arg)
+{
+	if (t->left) {
+		infix_walk(t->left, action, arg);
+	}
+	action(arg, t->key);
+	if (t->right) {
+		infix_walk(t->right, action, arg);
+	}
+}
+
+void tree_free(struct tree_node *t)
+{
+	if (t == NULL) {
+		return;
+	}
+	if (t->left) {
+		tree_free(t->left);
+	}
+	if (t->right) {
+		tree_free(t->right);
+	}
+	reftable_free(t);
+}
diff --git a/reftable/tree.h b/reftable/tree.h
new file mode 100644
index 0000000..fbdd002
--- /dev/null
+++ b/reftable/tree.h
@@ -0,0 +1,34 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef TREE_H
+#define TREE_H
+
+/* tree_node is a generic binary search tree. */
+struct tree_node {
+	void *key;
+	struct tree_node *left, *right;
+};
+
+/* looks for `key` in `rootp` using `compare` as comparison function. If insert
+ * is set, insert the key if it's not found. Else, return NULL.
+ */
+struct tree_node *tree_search(void *key, struct tree_node **rootp,
+			      int (*compare)(const void *, const void *),
+			      int insert);
+
+/* performs an infix walk of the tree. */
+void infix_walk(struct tree_node *t, void (*action)(void *arg, void *key),
+		void *arg);
+
+/*
+ * deallocates the tree nodes recursively. Keys should be deallocated separately
+ * by walking over the tree. */
+void tree_free(struct tree_node *t);
+
+#endif
diff --git a/reftable/tree_test.c b/reftable/tree_test.c
new file mode 100644
index 0000000..cbff125
--- /dev/null
+++ b/reftable/tree_test.c
@@ -0,0 +1,61 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "tree.h"
+
+#include "basics.h"
+#include "record.h"
+#include "test_framework.h"
+#include "reftable-tests.h"
+
+static int test_compare(const void *a, const void *b)
+{
+	return (char *)a - (char *)b;
+}
+
+struct curry {
+	void *last;
+};
+
+static void check_increasing(void *arg, void *key)
+{
+	struct curry *c = arg;
+	if (c->last) {
+		EXPECT(test_compare(c->last, key) < 0);
+	}
+	c->last = key;
+}
+
+static void test_tree(void)
+{
+	struct tree_node *root = NULL;
+
+	void *values[11] = { NULL };
+	struct tree_node *nodes[11] = { NULL };
+	int i = 1;
+	struct curry c = { NULL };
+	do {
+		nodes[i] = tree_search(values + i, &root, &test_compare, 1);
+		i = (i * 7) % 11;
+	} while (i != 1);
+
+	for (i = 1; i < ARRAY_SIZE(nodes); i++) {
+		EXPECT(values + i == nodes[i]->key);
+		EXPECT(nodes[i] ==
+		       tree_search(values + i, &root, &test_compare, 0));
+	}
+
+	infix_walk(root, check_increasing, &c);
+	tree_free(root);
+}
+
+int tree_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_tree);
+	return 0;
+}
diff --git a/reftable/writer.c b/reftable/writer.c
new file mode 100644
index 0000000..35c8649
--- /dev/null
+++ b/reftable/writer.c
@@ -0,0 +1,693 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "writer.h"
+
+#include "system.h"
+
+#include "block.h"
+#include "constants.h"
+#include "record.h"
+#include "tree.h"
+#include "reftable-error.h"
+
+/* finishes a block, and writes it to storage */
+static int writer_flush_block(struct reftable_writer *w);
+
+/* deallocates memory related to the index */
+static void writer_clear_index(struct reftable_writer *w);
+
+/* finishes writing a 'r' (refs) or 'g' (reflogs) section */
+static int writer_finish_public_section(struct reftable_writer *w);
+
+static struct reftable_block_stats *
+writer_reftable_block_stats(struct reftable_writer *w, uint8_t typ)
+{
+	switch (typ) {
+	case 'r':
+		return &w->stats.ref_stats;
+	case 'o':
+		return &w->stats.obj_stats;
+	case 'i':
+		return &w->stats.idx_stats;
+	case 'g':
+		return &w->stats.log_stats;
+	}
+	abort();
+	return NULL;
+}
+
+/* write data, queuing the padding for the next write. Returns negative for
+ * error. */
+static int padded_write(struct reftable_writer *w, uint8_t *data, size_t len,
+			int padding)
+{
+	int n = 0;
+	if (w->pending_padding > 0) {
+		uint8_t *zeroed = reftable_calloc(w->pending_padding);
+		int n = w->write(w->write_arg, zeroed, w->pending_padding);
+		if (n < 0)
+			return n;
+
+		w->pending_padding = 0;
+		reftable_free(zeroed);
+	}
+
+	w->pending_padding = padding;
+	n = w->write(w->write_arg, data, len);
+	if (n < 0)
+		return n;
+	n += padding;
+	return 0;
+}
+
+static void options_set_defaults(struct reftable_write_options *opts)
+{
+	if (opts->restart_interval == 0) {
+		opts->restart_interval = 16;
+	}
+
+	if (opts->hash_id == 0) {
+		opts->hash_id = GIT_SHA1_FORMAT_ID;
+	}
+	if (opts->block_size == 0) {
+		opts->block_size = DEFAULT_BLOCK_SIZE;
+	}
+}
+
+static int writer_version(struct reftable_writer *w)
+{
+	return (w->opts.hash_id == 0 || w->opts.hash_id == GIT_SHA1_FORMAT_ID) ?
+			     1 :
+			     2;
+}
+
+static int writer_write_header(struct reftable_writer *w, uint8_t *dest)
+{
+	memcpy(dest, "REFT", 4);
+
+	dest[4] = writer_version(w);
+
+	put_be24(dest + 5, w->opts.block_size);
+	put_be64(dest + 8, w->min_update_index);
+	put_be64(dest + 16, w->max_update_index);
+	if (writer_version(w) == 2) {
+		put_be32(dest + 24, w->opts.hash_id);
+	}
+	return header_size(writer_version(w));
+}
+
+static void writer_reinit_block_writer(struct reftable_writer *w, uint8_t typ)
+{
+	int block_start = 0;
+	if (w->next == 0) {
+		block_start = header_size(writer_version(w));
+	}
+
+	strbuf_release(&w->last_key);
+	block_writer_init(&w->block_writer_data, typ, w->block,
+			  w->opts.block_size, block_start,
+			  hash_size(w->opts.hash_id));
+	w->block_writer = &w->block_writer_data;
+	w->block_writer->restart_interval = w->opts.restart_interval;
+}
+
+static struct strbuf reftable_empty_strbuf = STRBUF_INIT;
+
+struct reftable_writer *
+reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
+		    void *writer_arg, struct reftable_write_options *opts)
+{
+	struct reftable_writer *wp =
+		reftable_calloc(sizeof(struct reftable_writer));
+	strbuf_init(&wp->block_writer_data.last_key, 0);
+	options_set_defaults(opts);
+	if (opts->block_size >= (1 << 24)) {
+		/* TODO - error return? */
+		abort();
+	}
+	wp->last_key = reftable_empty_strbuf;
+	wp->block = reftable_calloc(opts->block_size);
+	wp->write = writer_func;
+	wp->write_arg = writer_arg;
+	wp->opts = *opts;
+	writer_reinit_block_writer(wp, BLOCK_TYPE_REF);
+
+	return wp;
+}
+
+void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
+				uint64_t max)
+{
+	w->min_update_index = min;
+	w->max_update_index = max;
+}
+
+void reftable_writer_free(struct reftable_writer *w)
+{
+	reftable_free(w->block);
+	reftable_free(w);
+}
+
+struct obj_index_tree_node {
+	struct strbuf hash;
+	uint64_t *offsets;
+	size_t offset_len;
+	size_t offset_cap;
+};
+
+#define OBJ_INDEX_TREE_NODE_INIT    \
+	{                           \
+		.hash = STRBUF_INIT \
+	}
+
+static int obj_index_tree_node_compare(const void *a, const void *b)
+{
+	return strbuf_cmp(&((const struct obj_index_tree_node *)a)->hash,
+			  &((const struct obj_index_tree_node *)b)->hash);
+}
+
+static void writer_index_hash(struct reftable_writer *w, struct strbuf *hash)
+{
+	uint64_t off = w->next;
+
+	struct obj_index_tree_node want = { .hash = *hash };
+
+	struct tree_node *node = tree_search(&want, &w->obj_index_tree,
+					     &obj_index_tree_node_compare, 0);
+	struct obj_index_tree_node *key = NULL;
+	if (node == NULL) {
+		struct obj_index_tree_node empty = OBJ_INDEX_TREE_NODE_INIT;
+		key = reftable_malloc(sizeof(struct obj_index_tree_node));
+		*key = empty;
+
+		strbuf_reset(&key->hash);
+		strbuf_addbuf(&key->hash, hash);
+		tree_search((void *)key, &w->obj_index_tree,
+			    &obj_index_tree_node_compare, 1);
+	} else {
+		key = node->key;
+	}
+
+	if (key->offset_len > 0 && key->offsets[key->offset_len - 1] == off) {
+		return;
+	}
+
+	if (key->offset_len == key->offset_cap) {
+		key->offset_cap = 2 * key->offset_cap + 1;
+		key->offsets = reftable_realloc(
+			key->offsets, sizeof(uint64_t) * key->offset_cap);
+	}
+
+	key->offsets[key->offset_len++] = off;
+}
+
+static int writer_add_record(struct reftable_writer *w,
+			     struct reftable_record *rec)
+{
+	struct strbuf key = STRBUF_INIT;
+	int err = -1;
+	reftable_record_key(rec, &key);
+	if (strbuf_cmp(&w->last_key, &key) >= 0) {
+		err = REFTABLE_API_ERROR;
+		goto done;
+	}
+
+	strbuf_reset(&w->last_key);
+	strbuf_addbuf(&w->last_key, &key);
+	if (w->block_writer == NULL) {
+		writer_reinit_block_writer(w, reftable_record_type(rec));
+	}
+
+	assert(block_writer_type(w->block_writer) == reftable_record_type(rec));
+
+	if (block_writer_add(w->block_writer, rec) == 0) {
+		err = 0;
+		goto done;
+	}
+
+	err = writer_flush_block(w);
+	if (err < 0) {
+		goto done;
+	}
+
+	writer_reinit_block_writer(w, reftable_record_type(rec));
+	err = block_writer_add(w->block_writer, rec);
+	if (err < 0) {
+		/* we are writing into memory, so an error can only mean it
+		 * doesn't fit. */
+		err = REFTABLE_ENTRY_TOO_BIG_ERROR;
+		goto done;
+	}
+
+	err = 0;
+done:
+	strbuf_release(&key);
+	return err;
+}
+
+int reftable_writer_add_ref(struct reftable_writer *w,
+			    struct reftable_ref_record *ref)
+{
+	struct reftable_record rec = { NULL };
+	struct reftable_ref_record copy = *ref;
+	int err = 0;
+
+	if (ref->refname == NULL)
+		return REFTABLE_API_ERROR;
+	if (ref->update_index < w->min_update_index ||
+	    ref->update_index > w->max_update_index)
+		return REFTABLE_API_ERROR;
+
+	reftable_record_from_ref(&rec, &copy);
+	copy.update_index -= w->min_update_index;
+
+	err = writer_add_record(w, &rec);
+	if (err < 0)
+		return err;
+
+	if (!w->opts.skip_index_objects && reftable_ref_record_val1(ref)) {
+		struct strbuf h = STRBUF_INIT;
+		strbuf_add(&h, (char *)reftable_ref_record_val1(ref),
+			   hash_size(w->opts.hash_id));
+		writer_index_hash(w, &h);
+		strbuf_release(&h);
+	}
+
+	if (!w->opts.skip_index_objects && reftable_ref_record_val2(ref)) {
+		struct strbuf h = STRBUF_INIT;
+		strbuf_add(&h, reftable_ref_record_val2(ref),
+			   hash_size(w->opts.hash_id));
+		writer_index_hash(w, &h);
+		strbuf_release(&h);
+	}
+	return 0;
+}
+
+int reftable_writer_add_refs(struct reftable_writer *w,
+			     struct reftable_ref_record *refs, int n)
+{
+	int err = 0;
+	int i = 0;
+	QSORT(refs, n, reftable_ref_record_compare_name);
+	for (i = 0; err == 0 && i < n; i++) {
+		err = reftable_writer_add_ref(w, &refs[i]);
+	}
+	return err;
+}
+
+static int reftable_writer_add_log_verbatim(struct reftable_writer *w,
+					    struct reftable_log_record *log)
+{
+	struct reftable_record rec = { NULL };
+	if (w->block_writer &&
+	    block_writer_type(w->block_writer) == BLOCK_TYPE_REF) {
+		int err = writer_finish_public_section(w);
+		if (err < 0)
+			return err;
+	}
+
+	w->next -= w->pending_padding;
+	w->pending_padding = 0;
+
+	reftable_record_from_log(&rec, log);
+	return writer_add_record(w, &rec);
+}
+
+int reftable_writer_add_log(struct reftable_writer *w,
+			    struct reftable_log_record *log)
+{
+	char *input_log_message = NULL;
+	struct strbuf cleaned_message = STRBUF_INIT;
+	int err = 0;
+
+	if (log->value_type == REFTABLE_LOG_DELETION)
+		return reftable_writer_add_log_verbatim(w, log);
+
+	if (log->refname == NULL)
+		return REFTABLE_API_ERROR;
+
+	input_log_message = log->value.update.message;
+	if (!w->opts.exact_log_message && log->value.update.message) {
+		strbuf_addstr(&cleaned_message, log->value.update.message);
+		while (cleaned_message.len &&
+		       cleaned_message.buf[cleaned_message.len - 1] == '\n')
+			strbuf_setlen(&cleaned_message,
+				      cleaned_message.len - 1);
+		if (strchr(cleaned_message.buf, '\n')) {
+			/* multiple lines not allowed. */
+			err = REFTABLE_API_ERROR;
+			goto done;
+		}
+		strbuf_addstr(&cleaned_message, "\n");
+		log->value.update.message = cleaned_message.buf;
+	}
+
+	err = reftable_writer_add_log_verbatim(w, log);
+	log->value.update.message = input_log_message;
+done:
+	strbuf_release(&cleaned_message);
+	return err;
+}
+
+int reftable_writer_add_logs(struct reftable_writer *w,
+			     struct reftable_log_record *logs, int n)
+{
+	int err = 0;
+	int i = 0;
+	QSORT(logs, n, reftable_log_record_compare_key);
+
+	for (i = 0; err == 0 && i < n; i++) {
+		err = reftable_writer_add_log(w, &logs[i]);
+	}
+	return err;
+}
+
+static int writer_finish_section(struct reftable_writer *w)
+{
+	uint8_t typ = block_writer_type(w->block_writer);
+	uint64_t index_start = 0;
+	int max_level = 0;
+	int threshold = w->opts.unpadded ? 1 : 3;
+	int before_blocks = w->stats.idx_stats.blocks;
+	int err = writer_flush_block(w);
+	int i = 0;
+	struct reftable_block_stats *bstats = NULL;
+	if (err < 0)
+		return err;
+
+	while (w->index_len > threshold) {
+		struct reftable_index_record *idx = NULL;
+		int idx_len = 0;
+
+		max_level++;
+		index_start = w->next;
+		writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);
+
+		idx = w->index;
+		idx_len = w->index_len;
+
+		w->index = NULL;
+		w->index_len = 0;
+		w->index_cap = 0;
+		for (i = 0; i < idx_len; i++) {
+			struct reftable_record rec = { NULL };
+			reftable_record_from_index(&rec, idx + i);
+			if (block_writer_add(w->block_writer, &rec) == 0) {
+				continue;
+			}
+
+			err = writer_flush_block(w);
+			if (err < 0)
+				return err;
+
+			writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);
+
+			err = block_writer_add(w->block_writer, &rec);
+			if (err != 0) {
+				/* write into fresh block should always succeed
+				 */
+				abort();
+			}
+		}
+		for (i = 0; i < idx_len; i++) {
+			strbuf_release(&idx[i].last_key);
+		}
+		reftable_free(idx);
+	}
+
+	writer_clear_index(w);
+
+	err = writer_flush_block(w);
+	if (err < 0)
+		return err;
+
+	bstats = writer_reftable_block_stats(w, typ);
+	bstats->index_blocks = w->stats.idx_stats.blocks - before_blocks;
+	bstats->index_offset = index_start;
+	bstats->max_index_level = max_level;
+
+	/* Reinit lastKey, as the next section can start with any key. */
+	w->last_key.len = 0;
+
+	return 0;
+}
+
+struct common_prefix_arg {
+	struct strbuf *last;
+	int max;
+};
+
+static void update_common(void *void_arg, void *key)
+{
+	struct common_prefix_arg *arg = void_arg;
+	struct obj_index_tree_node *entry = key;
+	if (arg->last) {
+		int n = common_prefix_size(&entry->hash, arg->last);
+		if (n > arg->max) {
+			arg->max = n;
+		}
+	}
+	arg->last = &entry->hash;
+}
+
+struct write_record_arg {
+	struct reftable_writer *w;
+	int err;
+};
+
+static void write_object_record(void *void_arg, void *key)
+{
+	struct write_record_arg *arg = void_arg;
+	struct obj_index_tree_node *entry = key;
+	struct reftable_obj_record obj_rec = {
+		.hash_prefix = (uint8_t *)entry->hash.buf,
+		.hash_prefix_len = arg->w->stats.object_id_len,
+		.offsets = entry->offsets,
+		.offset_len = entry->offset_len,
+	};
+	struct reftable_record rec = { NULL };
+	if (arg->err < 0)
+		goto done;
+
+	reftable_record_from_obj(&rec, &obj_rec);
+	arg->err = block_writer_add(arg->w->block_writer, &rec);
+	if (arg->err == 0)
+		goto done;
+
+	arg->err = writer_flush_block(arg->w);
+	if (arg->err < 0)
+		goto done;
+
+	writer_reinit_block_writer(arg->w, BLOCK_TYPE_OBJ);
+	arg->err = block_writer_add(arg->w->block_writer, &rec);
+	if (arg->err == 0)
+		goto done;
+	obj_rec.offset_len = 0;
+	arg->err = block_writer_add(arg->w->block_writer, &rec);
+
+	/* Should be able to write into a fresh block. */
+	assert(arg->err == 0);
+
+done:;
+}
+
+static void object_record_free(void *void_arg, void *key)
+{
+	struct obj_index_tree_node *entry = key;
+
+	FREE_AND_NULL(entry->offsets);
+	strbuf_release(&entry->hash);
+	reftable_free(entry);
+}
+
+static int writer_dump_object_index(struct reftable_writer *w)
+{
+	struct write_record_arg closure = { .w = w };
+	struct common_prefix_arg common = { NULL };
+	if (w->obj_index_tree) {
+		infix_walk(w->obj_index_tree, &update_common, &common);
+	}
+	w->stats.object_id_len = common.max + 1;
+
+	writer_reinit_block_writer(w, BLOCK_TYPE_OBJ);
+
+	if (w->obj_index_tree) {
+		infix_walk(w->obj_index_tree, &write_object_record, &closure);
+	}
+
+	if (closure.err < 0)
+		return closure.err;
+	return writer_finish_section(w);
+}
+
+static int writer_finish_public_section(struct reftable_writer *w)
+{
+	uint8_t typ = 0;
+	int err = 0;
+
+	if (w->block_writer == NULL)
+		return 0;
+
+	typ = block_writer_type(w->block_writer);
+	err = writer_finish_section(w);
+	if (err < 0)
+		return err;
+	if (typ == BLOCK_TYPE_REF && !w->opts.skip_index_objects &&
+	    w->stats.ref_stats.index_blocks > 0) {
+		err = writer_dump_object_index(w);
+		if (err < 0)
+			return err;
+	}
+
+	if (w->obj_index_tree) {
+		infix_walk(w->obj_index_tree, &object_record_free, NULL);
+		tree_free(w->obj_index_tree);
+		w->obj_index_tree = NULL;
+	}
+
+	w->block_writer = NULL;
+	return 0;
+}
+
+int reftable_writer_close(struct reftable_writer *w)
+{
+	uint8_t footer[72];
+	uint8_t *p = footer;
+	int err = writer_finish_public_section(w);
+	int empty_table = w->next == 0;
+	if (err != 0)
+		goto done;
+	w->pending_padding = 0;
+	if (empty_table) {
+		/* Empty tables need a header anyway. */
+		uint8_t header[28];
+		int n = writer_write_header(w, header);
+		err = padded_write(w, header, n, 0);
+		if (err < 0)
+			goto done;
+	}
+
+	p += writer_write_header(w, footer);
+	put_be64(p, w->stats.ref_stats.index_offset);
+	p += 8;
+	put_be64(p, (w->stats.obj_stats.offset) << 5 | w->stats.object_id_len);
+	p += 8;
+	put_be64(p, w->stats.obj_stats.index_offset);
+	p += 8;
+
+	put_be64(p, w->stats.log_stats.offset);
+	p += 8;
+	put_be64(p, w->stats.log_stats.index_offset);
+	p += 8;
+
+	put_be32(p, crc32(0, footer, p - footer));
+	p += 4;
+
+	err = padded_write(w, footer, footer_size(writer_version(w)), 0);
+	if (err < 0)
+		goto done;
+
+	if (empty_table) {
+		err = REFTABLE_EMPTY_TABLE_ERROR;
+		goto done;
+	}
+
+done:
+	/* free up memory. */
+	block_writer_release(&w->block_writer_data);
+	writer_clear_index(w);
+	strbuf_release(&w->last_key);
+	return err;
+}
+
+static void writer_clear_index(struct reftable_writer *w)
+{
+	int i = 0;
+	for (i = 0; i < w->index_len; i++) {
+		strbuf_release(&w->index[i].last_key);
+	}
+
+	FREE_AND_NULL(w->index);
+	w->index_len = 0;
+	w->index_cap = 0;
+}
+
+static const int debug = 0;
+
+static int writer_flush_nonempty_block(struct reftable_writer *w)
+{
+	uint8_t typ = block_writer_type(w->block_writer);
+	struct reftable_block_stats *bstats =
+		writer_reftable_block_stats(w, typ);
+	uint64_t block_typ_off = (bstats->blocks == 0) ? w->next : 0;
+	int raw_bytes = block_writer_finish(w->block_writer);
+	int padding = 0;
+	int err = 0;
+	struct reftable_index_record ir = { .last_key = STRBUF_INIT };
+	if (raw_bytes < 0)
+		return raw_bytes;
+
+	if (!w->opts.unpadded && typ != BLOCK_TYPE_LOG) {
+		padding = w->opts.block_size - raw_bytes;
+	}
+
+	if (block_typ_off > 0) {
+		bstats->offset = block_typ_off;
+	}
+
+	bstats->entries += w->block_writer->entries;
+	bstats->restarts += w->block_writer->restart_len;
+	bstats->blocks++;
+	w->stats.blocks++;
+
+	if (debug) {
+		fprintf(stderr, "block %c off %" PRIu64 " sz %d (%d)\n", typ,
+			w->next, raw_bytes,
+			get_be24(w->block + w->block_writer->header_off + 1));
+	}
+
+	if (w->next == 0) {
+		writer_write_header(w, w->block);
+	}
+
+	err = padded_write(w, w->block, raw_bytes, padding);
+	if (err < 0)
+		return err;
+
+	if (w->index_cap == w->index_len) {
+		w->index_cap = 2 * w->index_cap + 1;
+		w->index = reftable_realloc(
+			w->index,
+			sizeof(struct reftable_index_record) * w->index_cap);
+	}
+
+	ir.offset = w->next;
+	strbuf_reset(&ir.last_key);
+	strbuf_addbuf(&ir.last_key, &w->block_writer->last_key);
+	w->index[w->index_len] = ir;
+
+	w->index_len++;
+	w->next += padding + raw_bytes;
+	w->block_writer = NULL;
+	return 0;
+}
+
+static int writer_flush_block(struct reftable_writer *w)
+{
+	if (w->block_writer == NULL)
+		return 0;
+	if (w->block_writer->entries == 0)
+		return 0;
+	return writer_flush_nonempty_block(w);
+}
+
+const struct reftable_stats *writer_stats(struct reftable_writer *w)
+{
+	return &w->stats;
+}
diff --git a/reftable/writer.h b/reftable/writer.h
new file mode 100644
index 0000000..09b8867
--- /dev/null
+++ b/reftable/writer.h
@@ -0,0 +1,50 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#ifndef WRITER_H
+#define WRITER_H
+
+#include "basics.h"
+#include "block.h"
+#include "tree.h"
+#include "reftable-writer.h"
+
+struct reftable_writer {
+	ssize_t (*write)(void *, const void *, size_t);
+	void *write_arg;
+	int pending_padding;
+	struct strbuf last_key;
+
+	/* offset of next block to write. */
+	uint64_t next;
+	uint64_t min_update_index, max_update_index;
+	struct reftable_write_options opts;
+
+	/* memory buffer for writing */
+	uint8_t *block;
+
+	/* writer for the current section. NULL or points to
+	 * block_writer_data */
+	struct block_writer *block_writer;
+
+	struct block_writer block_writer_data;
+
+	/* pending index records for the current section */
+	struct reftable_index_record *index;
+	size_t index_len;
+	size_t index_cap;
+
+	/*
+	 * tree for use with tsearch; used to populate the 'o' inverse OID
+	 * map */
+	struct tree_node *obj_index_tree;
+
+	struct reftable_stats stats;
+};
+
+#endif
diff --git a/remote-curl.c b/remote-curl.c
index d691563..0dabef2 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -1061,7 +1061,7 @@
 	client.in = -1;
 	client.out = -1;
 	client.git_cmd = 1;
-	client.argv = client_argv;
+	strvec_pushv(&client.args, client_argv);
 	if (start_command(&client))
 		exit(1);
 	write_or_die(client.in, preamble->buf, preamble->len);
diff --git a/remote.c b/remote.c
index f958543..a6d8ec6 100644
--- a/remote.c
+++ b/remote.c
@@ -21,33 +21,6 @@
 	size_t len;
 	const char *s;
 };
-struct rewrite {
-	const char *base;
-	size_t baselen;
-	struct counted_string *instead_of;
-	int instead_of_nr;
-	int instead_of_alloc;
-};
-struct rewrites {
-	struct rewrite **rewrite;
-	int rewrite_alloc;
-	int rewrite_nr;
-};
-
-static struct remote **remotes;
-static int remotes_alloc;
-static int remotes_nr;
-static struct hashmap remotes_hash;
-
-static struct branch **branches;
-static int branches_alloc;
-static int branches_nr;
-
-static struct branch *current_branch;
-static const char *pushremote_name;
-
-static struct rewrites rewrites;
-static struct rewrites rewrites_push;
 
 static int valid_remote(const struct remote *remote)
 {
@@ -92,17 +65,19 @@
 	remote->pushurl[remote->pushurl_nr++] = pushurl;
 }
 
-static void add_pushurl_alias(struct remote *remote, const char *url)
+static void add_pushurl_alias(struct remote_state *remote_state,
+			      struct remote *remote, const char *url)
 {
-	const char *pushurl = alias_url(url, &rewrites_push);
+	const char *pushurl = alias_url(url, &remote_state->rewrites_push);
 	if (pushurl != url)
 		add_pushurl(remote, pushurl);
 }
 
-static void add_url_alias(struct remote *remote, const char *url)
+static void add_url_alias(struct remote_state *remote_state,
+			  struct remote *remote, const char *url)
 {
-	add_url(remote, alias_url(url, &rewrites));
-	add_pushurl_alias(remote, url);
+	add_url(remote, alias_url(url, &remote_state->rewrites));
+	add_pushurl_alias(remote_state, remote, url);
 }
 
 struct remotes_hash_key {
@@ -127,13 +102,8 @@
 		return strcmp(a->name, b->name);
 }
 
-static inline void init_remotes_hash(void)
-{
-	if (!remotes_hash.cmpfn)
-		hashmap_init(&remotes_hash, remotes_hash_cmp, NULL, 0);
-}
-
-static struct remote *make_remote(const char *name, int len)
+static struct remote *make_remote(struct remote_state *remote_state,
+				  const char *name, int len)
 {
 	struct remote *ret;
 	struct remotes_hash_key lookup;
@@ -142,12 +112,11 @@
 	if (!len)
 		len = strlen(name);
 
-	init_remotes_hash();
 	lookup.str = name;
 	lookup.len = len;
 	hashmap_entry_init(&lookup_entry, memhash(name, len));
 
-	e = hashmap_get(&remotes_hash, &lookup_entry, &lookup);
+	e = hashmap_get(&remote_state->remotes_hash, &lookup_entry, &lookup);
 	if (e)
 		return container_of(e, struct remote, ent);
 
@@ -158,15 +127,38 @@
 	refspec_init(&ret->push, REFSPEC_PUSH);
 	refspec_init(&ret->fetch, REFSPEC_FETCH);
 
-	ALLOC_GROW(remotes, remotes_nr + 1, remotes_alloc);
-	remotes[remotes_nr++] = ret;
+	ALLOC_GROW(remote_state->remotes, remote_state->remotes_nr + 1,
+		   remote_state->remotes_alloc);
+	remote_state->remotes[remote_state->remotes_nr++] = ret;
 
 	hashmap_entry_init(&ret->ent, lookup_entry.hash);
-	if (hashmap_put_entry(&remotes_hash, ret, ent))
+	if (hashmap_put_entry(&remote_state->remotes_hash, ret, ent))
 		BUG("hashmap_put overwrote entry after hashmap_get returned NULL");
 	return ret;
 }
 
+static void remote_clear(struct remote *remote)
+{
+	int i;
+
+	free((char *)remote->name);
+	free((char *)remote->foreign_vcs);
+
+	for (i = 0; i < remote->url_nr; i++) {
+		free((char *)remote->url[i]);
+	}
+	FREE_AND_NULL(remote->pushurl);
+
+	for (i = 0; i < remote->pushurl_nr; i++) {
+		free((char *)remote->pushurl[i]);
+	}
+	FREE_AND_NULL(remote->pushurl);
+	free((char *)remote->receivepack);
+	free((char *)remote->uploadpack);
+	FREE_AND_NULL(remote->http_proxy);
+	FREE_AND_NULL(remote->http_proxy_authmethod);
+}
+
 static void add_merge(struct branch *branch, const char *name)
 {
 	ALLOC_GROW(branch->merge_name, branch->merge_nr + 1,
@@ -174,23 +166,74 @@
 	branch->merge_name[branch->merge_nr++] = name;
 }
 
-static struct branch *make_branch(const char *name, size_t len)
+struct branches_hash_key {
+	const char *str;
+	int len;
+};
+
+static int branches_hash_cmp(const void *unused_cmp_data,
+			     const struct hashmap_entry *eptr,
+			     const struct hashmap_entry *entry_or_key,
+			     const void *keydata)
+{
+	const struct branch *a, *b;
+	const struct branches_hash_key *key = keydata;
+
+	a = container_of(eptr, const struct branch, ent);
+	b = container_of(entry_or_key, const struct branch, ent);
+
+	if (key)
+		return strncmp(a->name, key->str, key->len) ||
+		       a->name[key->len];
+	else
+		return strcmp(a->name, b->name);
+}
+
+static struct branch *find_branch(struct remote_state *remote_state,
+				  const char *name, size_t len)
+{
+	struct branches_hash_key lookup;
+	struct hashmap_entry lookup_entry, *e;
+
+	if (!len)
+		len = strlen(name);
+
+	lookup.str = name;
+	lookup.len = len;
+	hashmap_entry_init(&lookup_entry, memhash(name, len));
+
+	e = hashmap_get(&remote_state->branches_hash, &lookup_entry, &lookup);
+	if (e)
+		return container_of(e, struct branch, ent);
+
+	return NULL;
+}
+
+static void die_on_missing_branch(struct repository *repo,
+				  struct branch *branch)
+{
+	/* branch == NULL is always valid because it represents detached HEAD. */
+	if (branch &&
+	    branch != find_branch(repo->remote_state, branch->name, 0))
+		die("branch %s was not found in the repository", branch->name);
+}
+
+static struct branch *make_branch(struct remote_state *remote_state,
+				  const char *name, size_t len)
 {
 	struct branch *ret;
-	int i;
 
-	for (i = 0; i < branches_nr; i++) {
-		if (!strncmp(name, branches[i]->name, len) &&
-		    !branches[i]->name[len])
-			return branches[i];
-	}
+	ret = find_branch(remote_state, name, len);
+	if (ret)
+		return ret;
 
-	ALLOC_GROW(branches, branches_nr + 1, branches_alloc);
 	CALLOC_ARRAY(ret, 1);
-	branches[branches_nr++] = ret;
 	ret->name = xstrndup(name, len);
 	ret->refname = xstrfmt("refs/heads/%s", ret->name);
 
+	hashmap_entry_init(&ret->ent, memhash(name, len));
+	if (hashmap_put_entry(&remote_state->branches_hash, ret, ent))
+		BUG("hashmap_put overwrote entry after hashmap_get returned NULL");
 	return ret;
 }
 
@@ -229,7 +272,8 @@
 	return s;
 }
 
-static void read_remotes_file(struct remote *remote)
+static void read_remotes_file(struct remote_state *remote_state,
+			      struct remote *remote)
 {
 	struct strbuf buf = STRBUF_INIT;
 	FILE *f = fopen_or_warn(git_path("remotes/%s", remote->name), "r");
@@ -244,7 +288,8 @@
 		strbuf_rtrim(&buf);
 
 		if (skip_prefix(buf.buf, "URL:", &v))
-			add_url_alias(remote, xstrdup(skip_spaces(v)));
+			add_url_alias(remote_state, remote,
+				      xstrdup(skip_spaces(v)));
 		else if (skip_prefix(buf.buf, "Push:", &v))
 			refspec_append(&remote->push, skip_spaces(v));
 		else if (skip_prefix(buf.buf, "Pull:", &v))
@@ -254,7 +299,8 @@
 	fclose(f);
 }
 
-static void read_branches_file(struct remote *remote)
+static void read_branches_file(struct remote_state *remote_state,
+			       struct remote *remote)
 {
 	char *frag;
 	struct strbuf buf = STRBUF_INIT;
@@ -286,7 +332,7 @@
 	else
 		frag = (char *)git_default_branch_name(0);
 
-	add_url_alias(remote, strbuf_detach(&buf, NULL));
+	add_url_alias(remote_state, remote, strbuf_detach(&buf, NULL));
 	refspec_appendf(&remote->fetch, "refs/heads/%s:refs/heads/%s",
 			frag, remote->name);
 
@@ -305,10 +351,12 @@
 	const char *subkey;
 	struct remote *remote;
 	struct branch *branch;
+	struct remote_state *remote_state = cb;
+
 	if (parse_config_key(key, "branch", &name, &namelen, &subkey) >= 0) {
 		if (!name)
 			return 0;
-		branch = make_branch(name, namelen);
+		branch = make_branch(remote_state, name, namelen);
 		if (!strcmp(subkey, "remote")) {
 			return git_config_string(&branch->remote_name, key, value);
 		} else if (!strcmp(subkey, "pushremote")) {
@@ -327,12 +375,14 @@
 		if (!strcmp(subkey, "insteadof")) {
 			if (!value)
 				return config_error_nonbool(key);
-			rewrite = make_rewrite(&rewrites, name, namelen);
+			rewrite = make_rewrite(&remote_state->rewrites, name,
+					       namelen);
 			add_instead_of(rewrite, xstrdup(value));
 		} else if (!strcmp(subkey, "pushinsteadof")) {
 			if (!value)
 				return config_error_nonbool(key);
-			rewrite = make_rewrite(&rewrites_push, name, namelen);
+			rewrite = make_rewrite(&remote_state->rewrites_push,
+					       name, namelen);
 			add_instead_of(rewrite, xstrdup(value));
 		}
 	}
@@ -342,7 +392,8 @@
 
 	/* Handle remote.* variables */
 	if (!name && !strcmp(subkey, "pushdefault"))
-		return git_config_string(&pushremote_name, key, value);
+		return git_config_string(&remote_state->pushremote_name, key,
+					 value);
 
 	if (!name)
 		return 0;
@@ -352,7 +403,7 @@
 			name);
 		return 0;
 	}
-	remote = make_remote(name, namelen);
+	remote = make_remote(remote_state, name, namelen);
 	remote->origin = REMOTE_CONFIG;
 	if (current_config_scope() == CONFIG_SCOPE_LOCAL ||
 	    current_config_scope() == CONFIG_SCOPE_WORKTREE)
@@ -422,44 +473,52 @@
 	return 0;
 }
 
-static void alias_all_urls(void)
+static void alias_all_urls(struct remote_state *remote_state)
 {
 	int i, j;
-	for (i = 0; i < remotes_nr; i++) {
+	for (i = 0; i < remote_state->remotes_nr; i++) {
 		int add_pushurl_aliases;
-		if (!remotes[i])
+		if (!remote_state->remotes[i])
 			continue;
-		for (j = 0; j < remotes[i]->pushurl_nr; j++) {
-			remotes[i]->pushurl[j] = alias_url(remotes[i]->pushurl[j], &rewrites);
+		for (j = 0; j < remote_state->remotes[i]->pushurl_nr; j++) {
+			remote_state->remotes[i]->pushurl[j] =
+				alias_url(remote_state->remotes[i]->pushurl[j],
+					  &remote_state->rewrites);
 		}
-		add_pushurl_aliases = remotes[i]->pushurl_nr == 0;
-		for (j = 0; j < remotes[i]->url_nr; j++) {
+		add_pushurl_aliases = remote_state->remotes[i]->pushurl_nr == 0;
+		for (j = 0; j < remote_state->remotes[i]->url_nr; j++) {
 			if (add_pushurl_aliases)
-				add_pushurl_alias(remotes[i], remotes[i]->url[j]);
-			remotes[i]->url[j] = alias_url(remotes[i]->url[j], &rewrites);
+				add_pushurl_alias(
+					remote_state, remote_state->remotes[i],
+					remote_state->remotes[i]->url[j]);
+			remote_state->remotes[i]->url[j] =
+				alias_url(remote_state->remotes[i]->url[j],
+					  &remote_state->rewrites);
 		}
 	}
 }
 
-static void read_config(void)
+static void read_config(struct repository *repo)
 {
-	static int loaded;
 	int flag;
 
-	if (loaded)
+	if (repo->remote_state->initialized)
 		return;
-	loaded = 1;
+	repo->remote_state->initialized = 1;
 
-	current_branch = NULL;
+	repo->remote_state->current_branch = NULL;
 	if (startup_info->have_repository) {
-		const char *head_ref = resolve_ref_unsafe("HEAD", 0, NULL, &flag);
+		int ignore_errno;
+		const char *head_ref = refs_resolve_ref_unsafe(
+			get_main_ref_store(repo), "HEAD", 0, NULL, &flag, &ignore_errno);
 		if (head_ref && (flag & REF_ISSYMREF) &&
 		    skip_prefix(head_ref, "refs/heads/", &head_ref)) {
-			current_branch = make_branch(head_ref, strlen(head_ref));
+			repo->remote_state->current_branch = make_branch(
+				repo->remote_state, head_ref, strlen(head_ref));
 		}
 	}
-	git_config(handle_config, NULL);
-	alias_all_urls();
+	repo_config(repo, handle_config, repo->remote_state);
+	alias_all_urls(repo->remote_state);
 }
 
 static int valid_remote_nick(const char *name)
@@ -474,7 +533,9 @@
 	return 1;
 }
 
-const char *remote_for_branch(struct branch *branch, int *explicit)
+static const char *remotes_remote_for_branch(struct remote_state *remote_state,
+					     struct branch *branch,
+					     int *explicit)
 {
 	if (branch && branch->remote_name) {
 		if (explicit)
@@ -486,32 +547,61 @@
 	return "origin";
 }
 
-const char *pushremote_for_branch(struct branch *branch, int *explicit)
+const char *remote_for_branch(struct branch *branch, int *explicit)
+{
+	read_config(the_repository);
+	die_on_missing_branch(the_repository, branch);
+
+	return remotes_remote_for_branch(the_repository->remote_state, branch,
+					 explicit);
+}
+
+static const char *
+remotes_pushremote_for_branch(struct remote_state *remote_state,
+			      struct branch *branch, int *explicit)
 {
 	if (branch && branch->pushremote_name) {
 		if (explicit)
 			*explicit = 1;
 		return branch->pushremote_name;
 	}
-	if (pushremote_name) {
+	if (remote_state->pushremote_name) {
 		if (explicit)
 			*explicit = 1;
-		return pushremote_name;
+		return remote_state->pushremote_name;
 	}
-	return remote_for_branch(branch, explicit);
+	return remotes_remote_for_branch(remote_state, branch, explicit);
 }
 
+const char *pushremote_for_branch(struct branch *branch, int *explicit)
+{
+	read_config(the_repository);
+	die_on_missing_branch(the_repository, branch);
+
+	return remotes_pushremote_for_branch(the_repository->remote_state,
+					     branch, explicit);
+}
+
+static struct remote *remotes_remote_get(struct remote_state *remote_state,
+					 const char *name);
+
 const char *remote_ref_for_branch(struct branch *branch, int for_push)
 {
+	read_config(the_repository);
+	die_on_missing_branch(the_repository, branch);
+
 	if (branch) {
 		if (!for_push) {
 			if (branch->merge_nr) {
 				return branch->merge_name[0];
 			}
 		} else {
-			const char *dst, *remote_name =
-				pushremote_for_branch(branch, NULL);
-			struct remote *remote = remote_get(remote_name);
+			const char *dst,
+				*remote_name = remotes_pushremote_for_branch(
+					the_repository->remote_state, branch,
+					NULL);
+			struct remote *remote = remotes_remote_get(
+				the_repository->remote_state, remote_name);
 
 			if (remote && remote->push.nr &&
 			    (dst = apply_refspecs(&remote->push,
@@ -523,41 +613,58 @@
 	return NULL;
 }
 
-static struct remote *remote_get_1(const char *name,
-				   const char *(*get_default)(struct branch *, int *))
+static struct remote *
+remotes_remote_get_1(struct remote_state *remote_state, const char *name,
+		     const char *(*get_default)(struct remote_state *,
+						struct branch *, int *))
 {
 	struct remote *ret;
 	int name_given = 0;
 
-	read_config();
-
 	if (name)
 		name_given = 1;
 	else
-		name = get_default(current_branch, &name_given);
+		name = get_default(remote_state, remote_state->current_branch,
+				   &name_given);
 
-	ret = make_remote(name, 0);
+	ret = make_remote(remote_state, name, 0);
 	if (valid_remote_nick(name) && have_git_dir()) {
 		if (!valid_remote(ret))
-			read_remotes_file(ret);
+			read_remotes_file(remote_state, ret);
 		if (!valid_remote(ret))
-			read_branches_file(ret);
+			read_branches_file(remote_state, ret);
 	}
 	if (name_given && !valid_remote(ret))
-		add_url_alias(ret, name);
+		add_url_alias(remote_state, ret, name);
 	if (!valid_remote(ret))
 		return NULL;
 	return ret;
 }
 
+static inline struct remote *
+remotes_remote_get(struct remote_state *remote_state, const char *name)
+{
+	return remotes_remote_get_1(remote_state, name,
+				    remotes_remote_for_branch);
+}
+
 struct remote *remote_get(const char *name)
 {
-	return remote_get_1(name, remote_for_branch);
+	read_config(the_repository);
+	return remotes_remote_get(the_repository->remote_state, name);
+}
+
+static inline struct remote *
+remotes_pushremote_get(struct remote_state *remote_state, const char *name)
+{
+	return remotes_remote_get_1(remote_state, name,
+				    remotes_pushremote_for_branch);
 }
 
 struct remote *pushremote_get(const char *name)
 {
-	return remote_get_1(name, pushremote_for_branch);
+	read_config(the_repository);
+	return remotes_pushremote_get(the_repository->remote_state, name);
 }
 
 int remote_is_configured(struct remote *remote, int in_repo)
@@ -572,12 +679,14 @@
 int for_each_remote(each_remote_fn fn, void *priv)
 {
 	int i, result = 0;
-	read_config();
-	for (i = 0; i < remotes_nr && !result; i++) {
-		struct remote *r = remotes[i];
-		if (!r)
+	read_config(the_repository);
+	for (i = 0; i < the_repository->remote_state->remotes_nr && !result;
+	     i++) {
+		struct remote *remote =
+			the_repository->remote_state->remotes[i];
+		if (!remote)
 			continue;
-		result = fn(r, priv);
+		result = fn(remote, priv);
 	}
 	return result;
 }
@@ -1642,7 +1751,7 @@
 	}
 }
 
-static void set_merge(struct branch *ret)
+static void set_merge(struct remote_state *remote_state, struct branch *ret)
 {
 	struct remote *remote;
 	char *ref;
@@ -1662,7 +1771,7 @@
 		return;
 	}
 
-	remote = remote_get(ret->remote_name);
+	remote = remotes_remote_get(remote_state, ret->remote_name);
 
 	CALLOC_ARRAY(ret->merge, ret->merge_nr);
 	for (i = 0; i < ret->merge_nr; i++) {
@@ -1683,12 +1792,13 @@
 {
 	struct branch *ret;
 
-	read_config();
+	read_config(the_repository);
 	if (!name || !*name || !strcmp(name, "HEAD"))
-		ret = current_branch;
+		ret = the_repository->remote_state->current_branch;
 	else
-		ret = make_branch(name, strlen(name));
-	set_merge(ret);
+		ret = make_branch(the_repository->remote_state, name,
+				  strlen(name));
+	set_merge(the_repository->remote_state, ret);
 	return ret;
 }
 
@@ -1759,11 +1869,14 @@
 	return ret;
 }
 
-static const char *branch_get_push_1(struct branch *branch, struct strbuf *err)
+static const char *branch_get_push_1(struct remote_state *remote_state,
+				     struct branch *branch, struct strbuf *err)
 {
 	struct remote *remote;
 
-	remote = remote_get(pushremote_for_branch(branch, NULL));
+	remote = remotes_remote_get(
+		remote_state,
+		remotes_pushremote_for_branch(remote_state, branch, NULL));
 	if (!remote)
 		return error_buf(err,
 				 _("branch '%s' has no remote for pushing"),
@@ -1821,11 +1934,15 @@
 
 const char *branch_get_push(struct branch *branch, struct strbuf *err)
 {
+	read_config(the_repository);
+	die_on_missing_branch(the_repository, branch);
+
 	if (!branch)
 		return error_buf(err, _("HEAD does not point to a branch"));
 
 	if (!branch->push_tracking_ref)
-		branch->push_tracking_ref = branch_get_push_1(branch, err);
+		branch->push_tracking_ref = branch_get_push_1(
+			the_repository->remote_state, branch, err);
 	return branch->push_tracking_ref;
 }
 
@@ -2585,3 +2702,29 @@
 			check_if_includes_upstream(ref);
 	}
 }
+
+struct remote_state *remote_state_new(void)
+{
+	struct remote_state *r = xmalloc(sizeof(*r));
+
+	memset(r, 0, sizeof(*r));
+
+	hashmap_init(&r->remotes_hash, remotes_hash_cmp, NULL, 0);
+	hashmap_init(&r->branches_hash, branches_hash_cmp, NULL, 0);
+	return r;
+}
+
+void remote_state_clear(struct remote_state *remote_state)
+{
+	int i;
+
+	for (i = 0; i < remote_state->remotes_nr; i++) {
+		remote_clear(remote_state->remotes[i]);
+	}
+	FREE_AND_NULL(remote_state->remotes);
+	remote_state->remotes_alloc = 0;
+	remote_state->remotes_nr = 0;
+
+	hashmap_clear_and_free(&remote_state->remotes_hash, struct remote, ent);
+	hashmap_clear_and_free(&remote_state->branches_hash, struct remote, ent);
+}
diff --git a/remote.h b/remote.h
index 5a59198..4a1209a 100644
--- a/remote.h
+++ b/remote.h
@@ -23,6 +23,40 @@
 	REMOTE_BRANCHES
 };
 
+struct rewrite {
+	const char *base;
+	size_t baselen;
+	struct counted_string *instead_of;
+	int instead_of_nr;
+	int instead_of_alloc;
+};
+
+struct rewrites {
+	struct rewrite **rewrite;
+	int rewrite_alloc;
+	int rewrite_nr;
+};
+
+struct remote_state {
+	struct remote **remotes;
+	int remotes_alloc;
+	int remotes_nr;
+	struct hashmap remotes_hash;
+
+	struct hashmap branches_hash;
+
+	struct branch *current_branch;
+	const char *pushremote_name;
+
+	struct rewrites rewrites;
+	struct rewrites rewrites_push;
+
+	int initialized;
+};
+
+void remote_state_clear(struct remote_state *remote_state);
+struct remote_state *remote_state_new(void);
+
 struct remote {
 	struct hashmap_entry ent;
 
@@ -256,6 +290,7 @@
  * branch_get(name) for "refs/heads/{name}", or with branch_get(NULL) for HEAD.
  */
 struct branch {
+	struct hashmap_entry ent;
 
 	/* The short name of the branch. */
 	const char *name;
diff --git a/repo-settings.c b/repo-settings.c
index b93e91a..00ca557 100644
--- a/repo-settings.c
+++ b/repo-settings.c
@@ -17,6 +17,9 @@
 	char *strval;
 	int manyfiles;
 
+	if (!r->gitdir)
+		BUG("Cannot add settings for uninitialized repository");
+
 	if (r->settings.initialized++)
 		return;
 
diff --git a/repository.c b/repository.c
index c5b90ba..34610c5 100644
--- a/repository.c
+++ b/repository.c
@@ -9,6 +9,7 @@
 #include "config.h"
 #include "object.h"
 #include "lockfile.h"
+#include "remote.h"
 #include "submodule-config.h"
 #include "sparse-index.h"
 #include "promisor-remote.h"
@@ -24,6 +25,7 @@
 
 	the_repo.index = &the_index;
 	the_repo.objects = raw_object_store_new();
+	the_repo.remote_state = remote_state_new();
 	the_repo.parsed_objects = parsed_object_pool_new();
 
 	repo_set_hash_algo(&the_repo, GIT_HASH_SHA1);
@@ -80,6 +82,8 @@
 	expand_base_dir(&repo->objects->odb->path, o->object_dir,
 			repo->commondir, "objects");
 
+	repo->objects->odb->disable_ref_updates = o->disable_ref_updates;
+
 	free(repo->objects->alternate_db);
 	repo->objects->alternate_db = xstrdup_or_null(o->alternate_db);
 	expand_base_dir(&repo->graft_file, o->graft_file,
@@ -164,6 +168,7 @@
 
 	repo->objects = raw_object_store_new();
 	repo->parsed_objects = parsed_object_pool_new();
+	repo->remote_state = remote_state_new();
 
 	if (repo_init_gitdir(repo, gitdir))
 		goto error;
@@ -270,6 +275,11 @@
 		promisor_remote_clear(repo->promisor_remote_config);
 		FREE_AND_NULL(repo->promisor_remote_config);
 	}
+
+	if (repo->remote_state) {
+		remote_state_clear(repo->remote_state);
+		FREE_AND_NULL(repo->remote_state);
+	}
 }
 
 int repo_read_index(struct repository *repo)
diff --git a/repository.h b/repository.h
index a057653..2b5cf97 100644
--- a/repository.h
+++ b/repository.h
@@ -11,6 +11,7 @@
 struct raw_object_store;
 struct submodule_cache;
 struct promisor_remote_config;
+struct remote_state;
 
 enum untracked_cache_setting {
 	UNTRACKED_CACHE_KEEP,
@@ -127,6 +128,9 @@
 	 */
 	struct index_state *index;
 
+	/* Repository's remotes and associated structures. */
+	struct remote_state *remote_state;
+
 	/* Repository's current hash algorithm, as serialized on disk. */
 	const struct git_hash_algo *hash_algo;
 
@@ -158,6 +162,7 @@
 	const char *graft_file;
 	const char *index_file;
 	const char *alternate_db;
+	int disable_ref_updates;
 };
 
 void repo_set_gitdir(struct repository *repo, const char *root,
diff --git a/revision.c b/revision.c
index 1981a08..ad4286f 100644
--- a/revision.c
+++ b/revision.c
@@ -44,10 +44,15 @@
 
 void show_object_with_name(FILE *out, struct object *obj, const char *name)
 {
-	const char *p;
-
 	fprintf(out, "%s ", oid_to_hex(&obj->oid));
-	for (p = name; *p && *p != '\n'; p++)
+	/*
+	 * This "for (const char *p = ..." is made as a first step towards
+	 * making use of such declarations elsewhere in our codebase.  If
+	 * it causes compilation problems on your platform, please report
+	 * it to the Git mailing list at git@vger.kernel.org. In the meantime,
+	 * adding -std=gnu99 to CFLAGS may help if you are with older GCC.
+	 */
+	for (const char *p = name; *p && *p != '\n'; p++)
 		fputc(*p, out);
 	fputc('\n', out);
 }
@@ -2295,11 +2300,11 @@
 		revs->left_only = 1;
 	} else if (!strcmp(arg, "--right-only")) {
 		if (revs->left_only)
-			die("--right-only is incompatible with --left-only");
+			die(_("options '%s' and '%s' cannot be used together"), "--right-only", "--left-only");
 		revs->right_only = 1;
 	} else if (!strcmp(arg, "--cherry")) {
 		if (revs->left_only)
-			die("--cherry is incompatible with --left-only");
+			die(_("options '%s' and '%s' cannot be used together"), "--cherry", "--left-only");
 		revs->cherry_mark = 1;
 		revs->right_only = 1;
 		revs->max_parents = 1;
@@ -2308,12 +2313,12 @@
 		revs->count = 1;
 	} else if (!strcmp(arg, "--cherry-mark")) {
 		if (revs->cherry_pick)
-			die("--cherry-mark is incompatible with --cherry-pick");
+			die(_("options '%s' and '%s' cannot be used together"), "--cherry-mark", "--cherry-pick");
 		revs->cherry_mark = 1;
 		revs->limited = 1; /* needs limit_list() */
 	} else if (!strcmp(arg, "--cherry-pick")) {
 		if (revs->cherry_mark)
-			die("--cherry-pick is incompatible with --cherry-mark");
+			die(_("options '%s' and '%s' cannot be used together"), "--cherry-pick", "--cherry-mark");
 		revs->cherry_pick = 1;
 		revs->limited = 1;
 	} else if (!strcmp(arg, "--objects")) {
@@ -2493,7 +2498,7 @@
 	} else if (!strcmp(arg, "--all-match")) {
 		revs->grep_filter.all_match = 1;
 	} else if (!strcmp(arg, "--invert-grep")) {
-		revs->invert_grep = 1;
+		revs->grep_filter.no_body_match = 1;
 	} else if ((argcount = parse_long_opt("encoding", argv, &optarg))) {
 		if (strcmp(optarg, "none"))
 			git_log_output_encoding = xstrdup(optarg);
@@ -2519,7 +2524,7 @@
 		return opts;
 	}
 	if (revs->graph && revs->track_linear)
-		die("--show-linear-break and --graph are incompatible");
+		die(_("options '%s' and '%s' cannot be used together"), "--show-linear-break", "--graph");
 
 	return 1;
 }
@@ -2862,24 +2867,24 @@
 	compile_grep_patterns(&revs->grep_filter);
 
 	if (revs->reverse && revs->reflog_info)
-		die("cannot combine --reverse with --walk-reflogs");
+		die(_("options '%s' and '%s' cannot be used together"), "--reverse", "--walk-reflogs");
 	if (revs->reflog_info && revs->limited)
 		die("cannot combine --walk-reflogs with history-limiting options");
 	if (revs->rewrite_parents && revs->children.name)
-		die("cannot combine --parents and --children");
+		die(_("options '%s' and '%s' cannot be used together"), "--parents", "--children");
 
 	/*
 	 * Limitations on the graph functionality
 	 */
 	if (revs->reverse && revs->graph)
-		die("cannot combine --reverse with --graph");
+		die(_("options '%s' and '%s' cannot be used together"), "--reverse", "--graph");
 
 	if (revs->reflog_info && revs->graph)
-		die("cannot combine --walk-reflogs with --graph");
+		die(_("options '%s' and '%s' cannot be used together"), "--walk-reflogs", "--graph");
 	if (revs->no_walk && revs->graph)
-		die("cannot combine --no-walk with --graph");
+		die(_("options '%s' and '%s' cannot be used together"), "--no-walk", "--graph");
 	if (!revs->reflog_info && revs->grep_filter.use_reflog_filter)
-		die("cannot use --grep-reflog without --walk-reflogs");
+		die(_("the option '%s' requires '%s'"), "--grep-reflog", "--walk-reflogs");
 
 	if (revs->line_level_traverse &&
 	    (revs->diffopt.output_format & ~(DIFF_FORMAT_PATCH | DIFF_FORMAT_NO_OUTPUT)))
@@ -3778,7 +3783,7 @@
 				     (char *)message, strlen(message));
 	strbuf_release(&buf);
 	unuse_commit_buffer(commit, message);
-	return opt->invert_grep ? !retval : retval;
+	return retval;
 }
 
 static inline int want_ancestry(const struct rev_info *revs)
diff --git a/revision.h b/revision.h
index 5578bb4..3f66147 100644
--- a/revision.h
+++ b/revision.h
@@ -246,8 +246,6 @@
 
 	/* Filter by commit log message */
 	struct grep_opt	grep_filter;
-	/* Negate the match of grep_filter */
-	int invert_grep;
 
 	/* Display history graph */
 	struct git_graph *graph;
diff --git a/run-command.c b/run-command.c
index f40df01..69dde42 100644
--- a/run-command.c
+++ b/run-command.c
@@ -340,15 +340,6 @@
 	child_close(fd[1]);
 }
 
-/*
- * parent will make it look like the child spewed a fatal error and died
- * this is needed to prevent changes to t0061.
- */
-static void fake_fatal(const char *err, va_list params)
-{
-	vreportf("fatal: ", err, params);
-}
-
 static void child_error_fn(const char *err, va_list params)
 {
 	const char msg[] = "error() should not be called in child\n";
@@ -372,15 +363,16 @@
 static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
 {
 	static void (*old_errfn)(const char *err, va_list params);
+	report_fn die_message_routine = get_die_message_routine();
 
 	old_errfn = get_error_routine();
-	set_error_routine(fake_fatal);
+	set_error_routine(die_message_routine);
 	errno = cerr->syserr;
 
 	switch (cerr->err) {
 	case CHILD_ERR_CHDIR:
 		error_errno("exec '%s': cd to '%s' failed",
-			    cmd->argv[0], cmd->dir);
+			    cmd->args.v[0], cmd->dir);
 		break;
 	case CHILD_ERR_DUP2:
 		error_errno("dup2() in child failed");
@@ -392,12 +384,12 @@
 		error_errno("sigprocmask failed restoring signals");
 		break;
 	case CHILD_ERR_ENOENT:
-		error_errno("cannot run %s", cmd->argv[0]);
+		error_errno("cannot run %s", cmd->args.v[0]);
 		break;
 	case CHILD_ERR_SILENT:
 		break;
 	case CHILD_ERR_ERRNO:
-		error_errno("cannot exec '%s'", cmd->argv[0]);
+		error_errno("cannot exec '%s'", cmd->args.v[0]);
 		break;
 	}
 	set_error_routine(old_errfn);
@@ -405,7 +397,7 @@
 
 static int prepare_cmd(struct strvec *out, const struct child_process *cmd)
 {
-	if (!cmd->argv[0])
+	if (!cmd->args.v[0])
 		BUG("command is empty");
 
 	/*
@@ -415,11 +407,11 @@
 	strvec_push(out, SHELL_PATH);
 
 	if (cmd->git_cmd) {
-		prepare_git_cmd(out, cmd->argv);
+		prepare_git_cmd(out, cmd->args.v);
 	} else if (cmd->use_shell) {
-		prepare_shell_cmd(out, cmd->argv);
+		prepare_shell_cmd(out, cmd->args.v);
 	} else {
-		strvec_pushv(out, cmd->argv);
+		strvec_pushv(out, cmd->args.v);
 	}
 
 	/*
@@ -552,20 +544,17 @@
 
 	while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 		;	/* nothing */
-	if (in_signal) {
-		if (WIFEXITED(status))
-			code = WEXITSTATUS(status);
-		return code;
-	}
 
 	if (waiting < 0) {
 		failed_errno = errno;
-		error_errno("waitpid for %s failed", argv0);
+		if (!in_signal)
+			error_errno("waitpid for %s failed", argv0);
 	} else if (waiting != pid) {
-		error("waitpid is confused (%s)", argv0);
+		if (!in_signal)
+			error("waitpid is confused (%s)", argv0);
 	} else if (WIFSIGNALED(status)) {
 		code = WTERMSIG(status);
-		if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
+		if (!in_signal && code != SIGINT && code != SIGQUIT && code != SIGPIPE)
 			error("%s died of signal %d", argv0, code);
 		/*
 		 * This return value is chosen so that code & 0xff
@@ -576,10 +565,12 @@
 	} else if (WIFEXITED(status)) {
 		code = WEXITSTATUS(status);
 	} else {
-		error("waitpid is confused (%s)", argv0);
+		if (!in_signal)
+			error("waitpid is confused (%s)", argv0);
 	}
 
-	clear_child_for_cleanup(pid);
+	if (!in_signal)
+		clear_child_for_cleanup(pid);
 
 	errno = failed_errno;
 	return code;
@@ -655,15 +646,10 @@
 		sq_quote_buf_pretty(&buf, cp->dir);
 		strbuf_addch(&buf, ';');
 	}
-	/*
-	 * The caller is responsible for initializing cp->env from
-	 * cp->env_array if needed. We only check one place.
-	 */
-	if (cp->env)
-		trace_add_env(&buf, cp->env);
+	trace_add_env(&buf, cp->env_array.v);
 	if (cp->git_cmd)
 		strbuf_addstr(&buf, " git");
-	sq_quote_argv_pretty(&buf, cp->argv);
+	sq_quote_argv_pretty(&buf, cp->args.v);
 
 	trace_printf("%s", buf.buf);
 	strbuf_release(&buf);
@@ -676,11 +662,6 @@
 	int failed_errno;
 	char *str;
 
-	if (!cmd->argv)
-		cmd->argv = cmd->args.v;
-	if (!cmd->env)
-		cmd->env = cmd->env_array.v;
-
 	/*
 	 * In case of errors we must keep the promise to close FDs
 	 * that have been passed in via ->in and ->out.
@@ -729,7 +710,7 @@
 			str = "standard error";
 fail_pipe:
 			error("cannot create %s pipe for %s: %s",
-				str, cmd->argv[0], strerror(failed_errno));
+				str, cmd->args.v[0], strerror(failed_errno));
 			child_process_clear(cmd);
 			errno = failed_errno;
 			return -1;
@@ -758,7 +739,7 @@
 		failed_errno = errno;
 		cmd->pid = -1;
 		if (!cmd->silent_exec_failure)
-			error_errno("cannot run %s", cmd->argv[0]);
+			error_errno("cannot run %s", cmd->args.v[0]);
 		goto end_of_spawn;
 	}
 
@@ -770,7 +751,7 @@
 		set_cloexec(null_fd);
 	}
 
-	childenv = prep_childenv(cmd->env);
+	childenv = prep_childenv(cmd->env_array.v);
 	atfork_prepare(&as);
 
 	/*
@@ -868,7 +849,7 @@
 	}
 	atfork_parent(&as);
 	if (cmd->pid < 0)
-		error_errno("cannot fork() for %s", cmd->argv[0]);
+		error_errno("cannot fork() for %s", cmd->args.v[0]);
 	else if (cmd->clean_on_exit)
 		mark_child_for_cleanup(cmd->pid, cmd);
 
@@ -885,7 +866,7 @@
 		 * At this point we know that fork() succeeded, but exec()
 		 * failed. Errors have been reported to our stderr.
 		 */
-		wait_or_whine(cmd->pid, cmd->argv[0], 0);
+		wait_or_whine(cmd->pid, cmd->args.v[0], 0);
 		child_err_spew(cmd, &cerr);
 		failed_errno = errno;
 		cmd->pid = -1;
@@ -902,7 +883,7 @@
 #else
 {
 	int fhin = 0, fhout = 1, fherr = 2;
-	const char **sargv = cmd->argv;
+	const char **sargv = cmd->args.v;
 	struct strvec nargv = STRVEC_INIT;
 
 	if (cmd->no_stdin)
@@ -929,20 +910,20 @@
 		fhout = dup(cmd->out);
 
 	if (cmd->git_cmd)
-		cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
+		cmd->args.v = prepare_git_cmd(&nargv, sargv);
 	else if (cmd->use_shell)
-		cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
+		cmd->args.v = prepare_shell_cmd(&nargv, sargv);
 
-	cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
+	cmd->pid = mingw_spawnvpe(cmd->args.v[0], cmd->args.v, (char**) cmd->env_array.v,
 			cmd->dir, fhin, fhout, fherr);
 	failed_errno = errno;
 	if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
-		error_errno("cannot spawn %s", cmd->argv[0]);
+		error_errno("cannot spawn %s", cmd->args.v[0]);
 	if (cmd->clean_on_exit && cmd->pid >= 0)
 		mark_child_for_cleanup(cmd->pid, cmd);
 
 	strvec_clear(&nargv);
-	cmd->argv = sargv;
+	cmd->args.v = sargv;
 	if (fhin != 0)
 		close(fhin);
 	if (fhout != 1)
@@ -992,7 +973,7 @@
 
 int finish_command(struct child_process *cmd)
 {
-	int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
+	int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 0);
 	trace2_child_exit(cmd, ret);
 	child_process_clear(cmd);
 	invalidate_lstat_cache();
@@ -1001,7 +982,7 @@
 
 int finish_command_in_signal(struct child_process *cmd)
 {
-	int ret = wait_or_whine(cmd->pid, cmd->argv[0], 1);
+	int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 1);
 	trace2_child_exit(cmd, ret);
 	return ret;
 }
@@ -1039,7 +1020,7 @@
 				 const char *const *env, const char *tr2_class)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
-	cmd.argv = argv;
+	strvec_pushv(&cmd.args, argv);
 	cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 	cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 	cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
@@ -1049,7 +1030,8 @@
 	cmd.wait_after_clean = opt & RUN_WAIT_AFTER_CLEAN ? 1 : 0;
 	cmd.close_object_store = opt & RUN_CLOSE_OBJECT_STORE ? 1 : 0;
 	cmd.dir = dir;
-	cmd.env = env;
+	if (env)
+		strvec_pushv(&cmd.env_array, (const char **)env);
 	cmd.trace2_child_class = tr2_class;
 	return run_command(&cmd);
 }
@@ -1082,7 +1064,9 @@
 
 static NORETURN void die_async(const char *err, va_list params)
 {
-	vreportf("fatal: ", err, params);
+	report_fn die_message_fn = get_die_message_routine();
+
+	die_message_fn(err, params);
 
 	if (in_async()) {
 		struct async *async = pthread_getspecific(async_key);
@@ -1335,7 +1319,8 @@
 	strvec_push(&hook.args, p);
 	while ((p = va_arg(args, const char *)))
 		strvec_push(&hook.args, p);
-	hook.env = env;
+	if (env)
+		strvec_pushv(&hook.env_array, (const char **)env);
 	hook.no_stdin = 1;
 	hook.stdout_to_stderr = 1;
 	hook.trace2_hook_name = name;
diff --git a/run-command.h b/run-command.h
index 4987826..2be5f5d 100644
--- a/run-command.h
+++ b/run-command.h
@@ -44,22 +44,35 @@
 struct child_process {
 
 	/**
-	 * The .argv member is set up as an array of string pointers (NULL
-	 * terminated), of which .argv[0] is the program name to run (usually
-	 * without a path). If the command to run is a git command, set argv[0] to
-	 * the command name without the 'git-' prefix and set .git_cmd = 1.
+	 * The .args is a `struct strvec', use that API to manipulate
+	 * it, e.g. strvec_pushv() to add an existing "const char **"
+	 * vector.
 	 *
-	 * Note that the ownership of the memory pointed to by .argv stays with the
-	 * caller, but it should survive until `finish_command` completes. If the
-	 * .argv member is NULL, `start_command` will point it at the .args
-	 * `strvec` (so you may use one or the other, but you must use exactly
-	 * one). The memory in .args will be cleaned up automatically during
+	 * If the command to run is a git command, set the first
+	 * element in the strvec to the command name without the
+	 * 'git-' prefix and set .git_cmd = 1.
+	 *
+	 * The memory in .args will be cleaned up automatically during
 	 * `finish_command` (or during `start_command` when it is unsuccessful).
-	 *
 	 */
-	const char **argv;
-
 	struct strvec args;
+
+	/**
+	 * Like .args the .env_array is a `struct strvec'.
+	 *
+	 * To modify the environment of the sub-process, specify an array of
+	 * environment settings. Each string in the array manipulates the
+	 * environment.
+	 *
+	 * - If the string is of the form "VAR=value", i.e. it contains '='
+	 *   the variable is added to the child process's environment.
+	 *
+	 * - If the string does not contain '=', it names an environment
+	 *   variable that will be removed from the child process's environment.
+	 *
+	 * The memory in .env_array will be cleaned up automatically during
+	 * `finish_command` (or during `start_command` when it is unsuccessful).
+	 */
 	struct strvec env_array;
 	pid_t pid;
 
@@ -96,23 +109,6 @@
 	 */
 	const char *dir;
 
-	/**
-	 * To modify the environment of the sub-process, specify an array of
-	 * string pointers (NULL terminated) in .env:
-	 *
-	 * - If the string is of the form "VAR=value", i.e. it contains '='
-	 *   the variable is added to the child process's environment.
-	 *
-	 * - If the string does not contain '=', it names an environment
-	 *   variable that will be removed from the child process's environment.
-	 *
-	 * If the .env member is NULL, `start_command` will point it at the
-	 * .env_array `strvec` (so you may use one or the other, but not both).
-	 * The memory in .env_array will be cleaned up automatically during
-	 * `finish_command` (or during `start_command` when it is unsuccessful).
-	 */
-	const char *const *env;
-
 	unsigned no_stdin:1;
 	unsigned no_stdout:1;
 	unsigned no_stderr:1;
diff --git a/sequencer.c b/sequencer.c
index ea96837..6abd721 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1164,18 +1164,14 @@
 			    const struct object_id *newoid)
 {
 	struct child_process proc = CHILD_PROCESS_INIT;
-	const char *argv[3];
 	int code;
 	struct strbuf sb = STRBUF_INIT;
+	const char *hook_path = find_hook("post-rewrite");
 
-	argv[0] = find_hook("post-rewrite");
-	if (!argv[0])
+	if (!hook_path)
 		return 0;
 
-	argv[1] = "amend";
-	argv[2] = NULL;
-
-	proc.argv = argv;
+	strvec_pushl(&proc.args, hook_path, "amend", NULL);
 	proc.in = -1;
 	proc.stdout_to_stderr = 1;
 	proc.trace2_hook_name = "post-rewrite";
@@ -1284,6 +1280,8 @@
 	struct pretty_print_context pctx = {0};
 	struct strbuf author_ident = STRBUF_INIT;
 	struct strbuf committer_ident = STRBUF_INIT;
+	struct ref_store *refs;
+	int resolve_errno;
 
 	commit = lookup_commit(r, oid);
 	if (!commit)
@@ -1333,9 +1331,13 @@
 	rev.diffopt.break_opt = 0;
 	diff_setup_done(&rev.diffopt);
 
-	head = resolve_ref_unsafe("HEAD", 0, NULL, NULL);
-	if (!head)
+	refs = get_main_ref_store(the_repository);
+	head = refs_resolve_ref_unsafe(refs, "HEAD", 0, NULL, NULL,
+				       &resolve_errno);
+	if (!head) {
+		errno = resolve_errno;
 		die_errno(_("unable to resolve HEAD after creating commit"));
+	}
 	if (!strcmp(head, "HEAD"))
 		head = _("detached HEAD");
 	else
@@ -3495,17 +3497,12 @@
 
 static int do_exec(struct repository *r, const char *command_line)
 {
-	struct strvec child_env = STRVEC_INIT;
 	const char *child_argv[] = { NULL, NULL };
 	int dirty, status;
 
 	fprintf(stderr, _("Executing: %s\n"), command_line);
 	child_argv[0] = command_line;
-	strvec_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));
-	strvec_pushf(&child_env, "GIT_WORK_TREE=%s",
-		     absolute_path(get_git_work_tree()));
-	status = run_command_v_opt_cd_env(child_argv, RUN_USING_SHELL, NULL,
-					  child_env.v);
+	status = run_command_v_opt(child_argv, RUN_USING_SHELL);
 
 	/* force re-reading of the cache */
 	if (discard_index(r->index) < 0 || repo_read_index(r) < 0)
@@ -3535,8 +3532,6 @@
 		status = 1;
 	}
 
-	strvec_clear(&child_env);
-
 	return status;
 }
 
@@ -4228,6 +4223,8 @@
 
 	cmd.git_cmd = 1;
 
+	if (startup_info->original_cwd)
+		cmd.dir = startup_info->original_cwd;
 	strvec_push(&cmd.args, "checkout");
 	strvec_push(&cmd.args, commit);
 	strvec_pushf(&cmd.env_array, GIT_REFLOG_ACTION "=%s", action);
@@ -5496,7 +5493,7 @@
 	}
 
 	/* insert or append final <commands> */
-	if (insert || nr == todo_list->nr) {
+	if (insert) {
 		ALLOC_GROW(items, nr + commands->nr, alloc);
 		COPY_ARRAY(items + nr, base_items, commands->nr);
 		nr += commands->nr;
diff --git a/setup.c b/setup.c
index 347d718..af3b8c0 100644
--- a/setup.c
+++ b/setup.c
@@ -12,6 +12,7 @@
 
 static struct startup_info the_startup_info;
 struct startup_info *startup_info = &the_startup_info;
+const char *tmp_original_cwd;
 
 /*
  * The input parameter must contain an absolute path, and it must already be
@@ -432,6 +433,69 @@
 	initialized = 1;
 }
 
+static void setup_original_cwd(void)
+{
+	struct strbuf tmp = STRBUF_INIT;
+	const char *worktree = NULL;
+	int offset = -1;
+
+	if (!tmp_original_cwd)
+		return;
+
+	/*
+	 * startup_info->original_cwd points to the current working
+	 * directory we inherited from our parent process, which is a
+	 * directory we want to avoid removing.
+	 *
+	 * For convience, we would like to have the path relative to the
+	 * worktree instead of an absolute path.
+	 *
+	 * Yes, startup_info->original_cwd is usually the same as 'prefix',
+	 * but differs in two ways:
+	 *   - prefix has a trailing '/'
+	 *   - if the user passes '-C' to git, that modifies the prefix but
+	 *     not startup_info->original_cwd.
+	 */
+
+	/* Normalize the directory */
+	strbuf_realpath(&tmp, tmp_original_cwd, 1);
+	free((char*)tmp_original_cwd);
+	tmp_original_cwd = NULL;
+	startup_info->original_cwd = strbuf_detach(&tmp, NULL);
+
+	/*
+	 * Get our worktree; we only protect the current working directory
+	 * if it's in the worktree.
+	 */
+	worktree = get_git_work_tree();
+	if (!worktree)
+		goto no_prevention_needed;
+
+	offset = dir_inside_of(startup_info->original_cwd, worktree);
+	if (offset >= 0) {
+		/*
+		 * If startup_info->original_cwd == worktree, that is already
+		 * protected and we don't need original_cwd as a secondary
+		 * protection measure.
+		 */
+		if (!*(startup_info->original_cwd + offset))
+			goto no_prevention_needed;
+
+		/*
+		 * original_cwd was inside worktree; precompose it just as
+		 * we do prefix so that built up paths will match
+		 */
+		startup_info->original_cwd = \
+			precompose_string_if_needed(startup_info->original_cwd
+						    + offset);
+		return;
+	}
+
+no_prevention_needed:
+	free((char*)startup_info->original_cwd);
+	startup_info->original_cwd = NULL;
+}
+
 static int read_worktree_config(const char *var, const char *value, void *vdata)
 {
 	struct repository_format *data = vdata;
@@ -1330,6 +1394,7 @@
 		setenv(GIT_PREFIX_ENVIRONMENT, "", 1);
 	}
 
+	setup_original_cwd();
 
 	strbuf_release(&dir);
 	strbuf_release(&gitdir);
diff --git a/sparse-index.c b/sparse-index.c
index 7b7ff79..a1d505d 100644
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -122,17 +122,17 @@
 	return 0;
 }
 
-int convert_to_sparse(struct index_state *istate, int flags)
+static int is_sparse_index_allowed(struct index_state *istate, int flags)
 {
-	int test_env;
-	if (istate->sparse_index || !istate->cache_nr ||
-	    !core_apply_sparse_checkout || !core_sparse_checkout_cone)
+	if (!core_apply_sparse_checkout || !core_sparse_checkout_cone)
 		return 0;
 
 	if (!istate->repo)
 		istate->repo = the_repository;
 
 	if (!(flags & SPARSE_INDEX_MEMORY_ONLY)) {
+		int test_env;
+
 		/*
 		 * The sparse index is not (yet) integrated with a split index.
 		 */
@@ -168,6 +168,19 @@
 	if (!istate->sparse_checkout_patterns->use_cone_patterns)
 		return 0;
 
+	return 1;
+}
+
+int convert_to_sparse(struct index_state *istate, int flags)
+{
+	/*
+	 * If the index is already sparse, empty, or otherwise
+	 * cannot be converted to sparse, do not convert.
+	 */
+	if (istate->sparse_index || !istate->cache_nr ||
+	    !is_sparse_index_allowed(istate, flags))
+		return 0;
+
 	/*
 	 * NEEDSWORK: If we have unmerged entries, then stay full.
 	 * Unmerged entries prevent the cache-tree extension from working.
@@ -175,17 +188,20 @@
 	if (index_has_unmerged_entries(istate))
 		return 0;
 
-	/* Clear and recompute the cache-tree */
-	cache_tree_free(&istate->cache_tree);
-	/*
-	 * Silently return if there is a problem with the cache tree update,
-	 * which might just be due to a conflict state in some entry.
-	 *
-	 * This might create new tree objects, so be sure to use
-	 * WRITE_TREE_MISSING_OK.
-	 */
-	if (cache_tree_update(istate, WRITE_TREE_MISSING_OK))
-		return 0;
+	if (!cache_tree_fully_valid(istate->cache_tree)) {
+		/* Clear and recompute the cache-tree */
+		cache_tree_free(&istate->cache_tree);
+
+		/*
+		 * Silently return if there is a problem with the cache tree update,
+		 * which might just be due to a conflict state in some entry.
+		 *
+		 * This might create new tree objects, so be sure to use
+		 * WRITE_TREE_MISSING_OK.
+		 */
+		if (cache_tree_update(istate, WRITE_TREE_MISSING_OK))
+			return 0;
+	}
 
 	remove_fsmonitor(istate);
 
@@ -313,6 +329,18 @@
 	trace2_region_leave("index", "ensure_full_index", istate->repo);
 }
 
+void ensure_correct_sparsity(struct index_state *istate)
+{
+	/*
+	 * If the index can be sparse, make it sparse. Otherwise,
+	 * ensure the index is full.
+	 */
+	if (is_sparse_index_allowed(istate, 0))
+		convert_to_sparse(istate, 0);
+	else
+		ensure_full_index(istate);
+}
+
 /*
  * This static global helps avoid infinite recursion between
  * expand_to_path() and index_file_exists().
diff --git a/sparse-index.h b/sparse-index.h
index 9f3d7bc..656bd83 100644
--- a/sparse-index.h
+++ b/sparse-index.h
@@ -4,6 +4,7 @@
 struct index_state;
 #define SPARSE_INDEX_MEMORY_ONLY (1 << 0)
 int convert_to_sparse(struct index_state *istate, int flags);
+void ensure_correct_sparsity(struct index_state *istate);
 
 /*
  * Some places in the codebase expect to search for a specific path.
diff --git a/strbuf.c b/strbuf.c
index b22e981..613fee8 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -1006,7 +1006,12 @@
 
 	/*
 	 * There is no portable way to pass timezone information to
-	 * strftime, so we handle %z and %Z here.
+	 * strftime, so we handle %z and %Z here. Likewise '%s', because
+	 * going back to an epoch time requires knowing the zone.
+	 *
+	 * Note that tz_offset is in the "[-+]HHMM" decimal form; this is what
+	 * we want for %z, but the computation for %s has to convert to number
+	 * of seconds.
 	 */
 	for (;;) {
 		const char *percent = strchrnul(fmt, '%');
@@ -1019,6 +1024,13 @@
 			strbuf_addstr(&munged_fmt, "%%");
 			fmt++;
 			break;
+		case 's':
+			strbuf_addf(&munged_fmt, "%"PRItime,
+				    (timestamp_t)tm_to_time_t(tm) -
+				    3600 * (tz_offset / 100) -
+				    60 * (tz_offset % 100));
+			fmt++;
+			break;
 		case 'z':
 			strbuf_addf(&munged_fmt, "%+05d", tz_offset);
 			fmt++;
diff --git a/strbuf.h b/strbuf.h
index 96512f8..76965a1 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -160,7 +160,7 @@
 static inline void strbuf_setlen(struct strbuf *sb, size_t len)
 {
 	if (len > (sb->alloc ? sb->alloc - 1 : 0))
-		die("BUG: strbuf_setlen() beyond buffer");
+		BUG("strbuf_setlen() beyond buffer");
 	sb->len = len;
 	if (sb->buf != strbuf_slopbuf)
 		sb->buf[len] = '\0';
diff --git a/sub-process.c b/sub-process.c
index dfa790d..cae56ae 100644
--- a/sub-process.c
+++ b/sub-process.c
@@ -187,7 +187,7 @@
 				*supported_capabilities |= capabilities[i].flag;
 		} else {
 			die("subprocess '%s' requested unsupported capability '%s'",
-			    process->argv[0], p);
+			    process->args.v[0], p);
 		}
 	}
 
diff --git a/symlinks.c b/symlinks.c
index 5232d02..c667baa 100644
--- a/symlinks.c
+++ b/symlinks.c
@@ -279,7 +279,9 @@
 {
 	while (removal.len > new_len) {
 		removal.buf[removal.len] = '\0';
-		if (rmdir(removal.buf))
+		if ((startup_info->original_cwd &&
+		     !strcmp(removal.buf, startup_info->original_cwd)) ||
+		    rmdir(removal.buf))
 			break;
 		do {
 			removal.len--;
@@ -293,6 +295,10 @@
 {
 	int match_len, last_slash, i, previous_slash;
 
+	if (startup_info->original_cwd &&
+	    !strcmp(name, startup_info->original_cwd))
+		return;	/* Do not remove the current working directory */
+
 	match_len = last_slash = i =
 		longest_path_match(name, len, removal.buf, removal.len,
 				   &previous_slash);
diff --git a/t/Makefile b/t/Makefile
index 882d26e..46cd5fc 100644
--- a/t/Makefile
+++ b/t/Makefile
@@ -71,12 +71,10 @@
 
 check-chainlint:
 	@mkdir -p '$(CHAINLINTTMP_SQ)' && \
-	err=0 && \
-	for i in $(CHAINLINTTESTS); do \
-		$(CHAINLINT) <chainlint/$$i.test | \
-		sed -e '/^# LINT: /d' >'$(CHAINLINTTMP_SQ)'/$$i.actual && \
-		diff -u chainlint/$$i.expect '$(CHAINLINTTMP_SQ)'/$$i.actual || err=1; \
-	done && exit $$err
+	sed -e '/^# LINT: /d' $(patsubst %,chainlint/%.test,$(CHAINLINTTESTS)) >'$(CHAINLINTTMP_SQ)'/tests && \
+	sed -e '/^[ 	]*$$/d' $(patsubst %,chainlint/%.expect,$(CHAINLINTTESTS)) >'$(CHAINLINTTMP_SQ)'/expect && \
+	$(CHAINLINT) '$(CHAINLINTTMP_SQ)'/tests | grep -v '^[	]*$$' >'$(CHAINLINTTMP_SQ)'/actual && \
+	diff -u '$(CHAINLINTTMP_SQ)'/expect '$(CHAINLINTTMP_SQ)'/actual
 
 test-lint: test-lint-duplicates test-lint-executable test-lint-shell-syntax \
 	test-lint-filenames
diff --git a/t/README b/t/README
index 29f7235..f48e054 100644
--- a/t/README
+++ b/t/README
@@ -466,6 +466,12 @@
 complete or needs to be abandoned for whatever reason (in which case the
 migrated codepaths still retain their performance benefits).
 
+GIT_TEST_REQUIRE_PREREQ=<list> allows specifying a space separated list of
+prereqs that are required to succeed. If a prereq in this list is triggered by
+a test and then fails then the whole test run will abort. This can help to make
+sure the expected tests are executed and not silently skipped when their
+dependency breaks or is simply not present in a new environment.
+
 Naming Tests
 ------------
 
diff --git a/t/aggregate-results.sh b/t/aggregate-results.sh
index 7913e20..7f2b83b 100755
--- a/t/aggregate-results.sh
+++ b/t/aggregate-results.sh
@@ -6,6 +6,7 @@
 failed=0
 broken=0
 total=0
+missing_prereq=
 
 while read file
 do
@@ -30,10 +31,26 @@
 			broken=$(($broken + $value)) ;;
 		total)
 			total=$(($total + $value)) ;;
+		missing_prereq)
+			missing_prereq="$missing_prereq,$value" ;;
 		esac
 	done <"$file"
 done
 
+if test -n "$missing_prereq"
+then
+	unique_missing_prereq=$(
+		echo $missing_prereq |
+		tr -s "," "\n" |
+		grep -v '^$' |
+		sort -u |
+		paste -s -d ' ')
+	if test -n "$unique_missing_prereq"
+	then
+		printf "\nmissing prereq: $unique_missing_prereq\n\n"
+	fi
+fi
+
 if test -n "$failed_tests"
 then
 	printf "\nfailed test(s):$failed_tests\n\n"
diff --git a/t/annotate-tests.sh b/t/annotate-tests.sh
index d3b299e..09e86f9 100644
--- a/t/annotate-tests.sh
+++ b/t/annotate-tests.sh
@@ -161,7 +161,7 @@
 			GIT_AUTHOR_NAME=$i$j GIT_AUTHOR_EMAIL=$i$j@test.git \
 			git commit -a -m "$i$j" &&
 			commit=$(git rev-parse --verify HEAD) &&
-			graft="$graft$commit "
+			graft="$graft$commit " || return 1
 		done
 	done &&
 	printf "%s " $graft >.git/info/grafts &&
diff --git a/t/chainlint.sed b/t/chainlint.sed
index 8a25c5b..dc4ce37 100644
--- a/t/chainlint.sed
+++ b/t/chainlint.sed
@@ -24,9 +24,9 @@
 # in order to avoid misinterpreting the ")" in constructs such as "x=$(...)"
 # and "case $x in *)" as ending the subshell.
 #
-# Lines missing a final "&&" are flagged with "?!AMP?!", and lines which chain
-# commands with ";" internally rather than "&&" are flagged "?!SEMI?!". A line
-# may be flagged for both violations.
+# Lines missing a final "&&" are flagged with "?!AMP?!", as are lines which
+# chain commands with ";" internally rather than "&&". A line may be flagged
+# for both violations.
 #
 # Detection of a missing &&-link in a multi-line subshell is complicated by the
 # fact that the last statement before the closing ")" must not end with "&&".
@@ -47,8 +47,8 @@
 # "?!AMP?!" violation is removed from the "bar" line (retrieved from the "hold"
 # area) since the final statement of a subshell must not end with "&&". The
 # final line of a subshell may still break the &&-chain by using ";" internally
-# to chain commands together rather than "&&", so "?!SEMI?!" is never removed
-# from a line (even though "?!AMP?!" might be).
+# to chain commands together rather than "&&", but an internal "?!AMP?!" is
+# never removed from a line even though a line-ending "?!AMP?!" might be.
 #
 # Care is taken to recognize the last _statement_ of a multi-line subshell, not
 # necessarily the last textual _line_ within the subshell, since &&-chaining
@@ -62,26 +62,20 @@
 # receives similar treatment.
 #
 # Swallowing here-docs with arbitrary tags requires a bit of finesse. When a
-# line such as "cat <<EOF >out" is seen, the here-doc tag is moved to the front
-# of the line enclosed in angle brackets as a sentinel, giving "<EOF>cat >out".
+# line such as "cat <<EOF" is seen, the here-doc tag is copied to the front of
+# the line enclosed in angle brackets as a sentinel, giving "<EOF>cat <<EOF".
 # As each subsequent line is read, it is appended to the target line and a
 # (whitespace-loose) back-reference match /^<(.*)>\n\1$/ is attempted to see if
 # the content inside "<...>" matches the entirety of the newly-read line. For
 # instance, if the next line read is "some data", when concatenated with the
-# target line, it becomes "<EOF>cat >out\nsome data", and a match is attempted
+# target line, it becomes "<EOF>cat <<EOF\nsome data", and a match is attempted
 # to see if "EOF" matches "some data". Since it doesn't, the next line is
 # attempted. When a line consisting of only "EOF" (and possible whitespace) is
-# encountered, it is appended to the target line giving "<EOF>cat >out\nEOF",
+# encountered, it is appended to the target line giving "<EOF>cat <<EOF\nEOF",
 # in which case the "EOF" inside "<...>" does match the text following the
 # newline, thus the closing here-doc tag has been found. The closing tag line
 # and the "<...>" prefix on the target line are then discarded, leaving just
-# the target line "cat >out".
-#
-# To facilitate regression testing (and manual debugging), a ">" annotation is
-# applied to the line containing ")" which closes a subshell, ">>" to a line
-# closing a nested subshell, and ">>>" to a line closing both at once. This
-# makes it easy to detect whether the heuristics correctly identify
-# end-of-subshell.
+# the target line "cat <<EOF".
 #------------------------------------------------------------------------------
 
 # incomplete line -- slurp up next line
@@ -94,9 +88,9 @@
 
 # here-doc -- swallow it to avoid false hits within its body (but keep the
 # command to which it was attached)
-/<<[ 	]*[-\\'"]*[A-Za-z0-9_]/ {
-	s/^\(.*\)<<[ 	]*[-\\'"]*\([A-Za-z0-9_][A-Za-z0-9_]*\)['"]*/<\2>\1<</
-	s/[ 	]*<<//
+/<<-*[ 	]*[\\'"]*[A-Za-z0-9_]/ {
+	/"[^"]*<<[^"]*"/bnotdoc
+	s/^\(.*<<-*[ 	]*\)[\\'"]*\([A-Za-z0-9_][A-Za-z0-9_]*\)['"]*/<\2>\1\2/
 	:hered
 	N
 	/^<\([^>]*\)>.*\n[ 	]*\1[ 	]*$/!{
@@ -106,6 +100,7 @@
 	s/^<[^>]*>//
 	s/\n.*$//
 }
+:notdoc
 
 # one-liner "(...) &&"
 /^[ 	]*!*[ 	]*(..*)[ 	]*&&[ 	]*$/boneline
@@ -126,7 +121,7 @@
 # "&&" (but not ";" in a string)
 :oneline
 /;/{
-	/"[^"]*;[^"]*"/!s/^/?!SEMI?!/
+	/"[^"]*;[^"]*"/!s/;/; ?!AMP?!/
 }
 b
 
@@ -136,11 +131,15 @@
 	h
 	bnextln
 }
-# "(..." line -- split off and stash "(", then process "..." as its own line
+# "(..." line -- "(" opening subshell cuddled with command; temporarily replace
+# "(" with sentinel "^" and process the line as if "(" had been seen solo on
+# the preceding line; this temporary replacement prevents several rules from
+# accidentally thinking "(" introduces a nested subshell; "^" is changed back
+# to "(" at output time
 x
-s/.*/(/
+s/.*//
 x
-s/(//
+s/(/^/
 bslurp
 
 :nextln
@@ -157,8 +156,10 @@
 	/"[^'"]*'[^'"]*"/!bsqstr
 }
 :folded
-# here-doc -- swallow it
-/<<[ 	]*[-\\'"]*[A-Za-z0-9_]/bheredoc
+# here-doc -- swallow it (but not "<<" in a string)
+/<<-*[ 	]*[\\'"]*[A-Za-z0-9_]/{
+	/"[^"]*<<[^"]*"/!bheredoc
+}
 # comment or empty line -- discard since final non-comment, non-empty line
 # before closing ")", "done", "elsif", "else", or "fi" will need to be
 # re-visited to drop "suspect" marking since final line of those constructs
@@ -171,12 +172,12 @@
 	/"[^"]*#[^"]*"/!s/[ 	]#.*$//
 }
 # one-liner "case ... esac"
-/^[ 	]*case[ 	]*..*esac/bchkchn
+/^[ 	^]*case[ 	]*..*esac/bchkchn
 # multi-line "case ... esac"
-/^[ 	]*case[ 	]..*[ 	]in/bcase
+/^[ 	^]*case[ 	]..*[ 	]in/bcase
 # multi-line "for ... done" or "while ... done"
-/^[ 	]*for[ 	]..*[ 	]in/bcont
-/^[ 	]*while[ 	]/bcont
+/^[ 	^]*for[ 	]..*[ 	]in/bcont
+/^[ 	^]*while[ 	]/bcont
 /^[ 	]*do[ 	]/bcont
 /^[ 	]*do[ 	]*$/bcont
 /;[ 	]*do/bcont
@@ -187,7 +188,7 @@
 /||[ 	]*exit[ 	]/bcont
 /||[ 	]*exit[ 	]*$/bcont
 # multi-line "if...elsif...else...fi"
-/^[ 	]*if[ 	]/bcont
+/^[ 	^]*if[ 	]/bcont
 /^[ 	]*then[ 	]/bcont
 /^[ 	]*then[ 	]*$/bcont
 /;[ 	]*then/bcont
@@ -200,15 +201,15 @@
 /^[ 	]*fi[ 	]*[<>|]/bdone
 /^[ 	]*fi[ 	]*)/bdone
 # nested one-liner "(...) &&"
-/^[ 	]*(.*)[ 	]*&&[ 	]*$/bchkchn
+/^[ 	^]*(.*)[ 	]*&&[ 	]*$/bchkchn
 # nested one-liner "(...)"
-/^[ 	]*(.*)[ 	]*$/bchkchn
+/^[ 	^]*(.*)[ 	]*$/bchkchn
 # nested one-liner "(...) >x" (or "2>x" or "<x" or "|x")
-/^[ 	]*(.*)[ 	]*[0-9]*[<>|]/bchkchn
+/^[ 	^]*(.*)[ 	]*[0-9]*[<>|]/bchkchn
 # nested multi-line "(...\n...)"
-/^[ 	]*(/bnest
+/^[ 	^]*(/bnest
 # multi-line "{...\n...}"
-/^[ 	]*{/bblock
+/^[ 	^]*{/bblock
 # closing ")" on own line -- exit subshell
 /^[ 	]*)/bclssolo
 # "$((...))" -- arithmetic expansion; not closing ")"
@@ -230,16 +231,18 @@
 # string and not ";;" in one-liner "case...esac")
 /;/{
 	/;;/!{
-		/"[^"]*;[^"]*"/!s/^/?!SEMI?!/
+		/"[^"]*;[^"]*"/!s/;/; ?!AMP?!/
 	}
 }
 # line ends with pipe "...|" -- valid; not missing "&&"
 /|[ 	]*$/bcont
 # missing end-of-line "&&" -- mark suspect
-/&&[ 	]*$/!s/^/?!AMP?!/
+/&&[ 	]*$/!s/$/ ?!AMP?!/
 :cont
 # retrieve and print previous line
 x
+s/^\([ 	]*\)^/\1(/
+s/?!HERE?!/<</g
 n
 bslurp
 
@@ -280,8 +283,7 @@
 # found here-doc -- swallow it to avoid false hits within its body (but keep
 # the command to which it was attached)
 :heredoc
-s/^\(.*\)<<[ 	]*[-\\'"]*\([A-Za-z0-9_][A-Za-z0-9_]*\)['"]*/<\2>\1<</
-s/[ 	]*<<//
+s/^\(.*\)<<\(-*[ 	]*\)[\\'"]*\([A-Za-z0-9_][A-Za-z0-9_]*\)['"]*/<\3>\1?!HERE?!\2\3/
 :hdocsub
 N
 /^<\([^>]*\)>.*\n[ 	]*\1[ 	]*$/!{
@@ -295,7 +297,15 @@
 # found "case ... in" -- pass through untouched
 :case
 x
+s/^\([ 	]*\)^/\1(/
+s/?!HERE?!/<</g
 n
+:cascom
+/^[ 	]*#/{
+	N
+	s/.*\n//
+	bcascom
+}
 /^[ 	]*esac/bslurp
 bcase
 
@@ -303,7 +313,7 @@
 # that line legitimately lacks "&&"
 :else
 x
-s/?!AMP?!//
+s/\( ?!AMP?!\)* ?!AMP?!$//
 x
 bcont
 
@@ -311,7 +321,7 @@
 # "suspect" from final contained line since that line legitimately lacks "&&"
 :done
 x
-s/?!AMP?!//
+s/\( ?!AMP?!\)* ?!AMP?!$//
 x
 # is 'done' or 'fi' cuddled with ")" to close subshell?
 /done.*)/bclose
@@ -322,11 +332,18 @@
 :nest
 x
 :nstslrp
+s/^\([ 	]*\)^/\1(/
+s/?!HERE?!/<</g
 n
+:nstcom
+# comment -- not closing ")" if in comment
+/^[ 	]*#/{
+	N
+	s/.*\n//
+	bnstcom
+}
 # closing ")" on own line -- stop nested slurp
 /^[ 	]*)/bnstcl
-# comment -- not closing ")" if in comment
-/^[ 	]*#/bnstcnt
 # "$((...))" -- arithmetic expansion; not closing ")"
 /\$(([^)][^)]*))[^)]*$/bnstcnt
 # "$(...)" -- command substitution; not closing ")"
@@ -337,7 +354,6 @@
 x
 bnstslrp
 :nstcl
-s/^/>>/
 # is it "))" which closes nested and parent subshells?
 /)[ 	]*)/bslurp
 bchkchn
@@ -345,7 +361,15 @@
 # found multi-line "{...\n...}" block -- pass through untouched
 :block
 x
+s/^\([ 	]*\)^/\1(/
+s/?!HERE?!/<</g
 n
+:blkcom
+/^[ 	]*#/{
+	N
+	s/.*\n//
+	bblkcom
+}
 # closing "}" -- stop block slurp
 /}/bchkchn
 bblock
@@ -354,16 +378,22 @@
 # since that line legitimately lacks "&&" and exit subshell loop
 :clssolo
 x
-s/?!AMP?!//
+s/\( ?!AMP?!\)* ?!AMP?!$//
+s/^\([ 	]*\)^/\1(/
+s/?!HERE?!/<</g
 p
 x
-s/^/>/
+s/^\([ 	]*\)^/\1(/
+s/?!HERE?!/<</g
 b
 
 # found closing "...)" -- exit subshell loop
 :close
 x
+s/^\([ 	]*\)^/\1(/
+s/?!HERE?!/<</g
 p
 x
-s/^/>/
+s/^\([ 	]*\)^/\1(/
+s/?!HERE?!/<</g
 b
diff --git a/t/chainlint/arithmetic-expansion.expect b/t/chainlint/arithmetic-expansion.expect
index 09457d3..46ee104 100644
--- a/t/chainlint/arithmetic-expansion.expect
+++ b/t/chainlint/arithmetic-expansion.expect
@@ -2,8 +2,8 @@
 	foo &&
 	bar=$((42 + 1)) &&
 	baz
->) &&
+) &&
 (
-?!AMP?!	bar=$((42 + 1))
+	bar=$((42 + 1)) ?!AMP?!
 	baz
->)
+)
diff --git a/t/chainlint/bash-array.expect b/t/chainlint/bash-array.expect
index c4a830d..4c34eae 100644
--- a/t/chainlint/bash-array.expect
+++ b/t/chainlint/bash-array.expect
@@ -2,9 +2,9 @@
 	foo &&
 	bar=(gumbo stumbo wumbo) &&
 	baz
->) &&
+) &&
 (
 	foo &&
 	bar=${#bar[@]} &&
 	baz
->)
+)
diff --git a/t/chainlint/blank-line.expect b/t/chainlint/blank-line.expect
index 3be939e..f76fde1 100644
--- a/t/chainlint/blank-line.expect
+++ b/t/chainlint/blank-line.expect
@@ -1,4 +1,4 @@
 (
 	nothing &&
 	something
->)
+)
diff --git a/t/chainlint/blank-line.test b/t/chainlint/blank-line.test
index f6dd143..0fdf15b 100644
--- a/t/chainlint/blank-line.test
+++ b/t/chainlint/blank-line.test
@@ -3,7 +3,7 @@
 	nothing &&
 
 	something
-# LINT: swallow blank lines since final _statement_ before subshell end is
+# LINT: ignore blank lines since final _statement_ before subshell end is
 # LINT: significant to "&&"-check, not final _line_ (which might be blank)
 
 
diff --git a/t/chainlint/block-comment.expect b/t/chainlint/block-comment.expect
new file mode 100644
index 0000000..d10b2ee
--- /dev/null
+++ b/t/chainlint/block-comment.expect
@@ -0,0 +1,6 @@
+(
+	{
+		echo a &&
+		echo b
+	}
+)
diff --git a/t/chainlint/block-comment.test b/t/chainlint/block-comment.test
new file mode 100644
index 0000000..df2beea
--- /dev/null
+++ b/t/chainlint/block-comment.test
@@ -0,0 +1,8 @@
+(
+	{
+		# show a
+		echo a &&
+		# show b
+		echo b
+	}
+)
diff --git a/t/chainlint/block.expect b/t/chainlint/block.expect
index fed7e89..da60257 100644
--- a/t/chainlint/block.expect
+++ b/t/chainlint/block.expect
@@ -7,6 +7,6 @@
 	bar &&
 	{
 		echo c
-?!AMP?!	}
+	} ?!AMP?!
 	baz
->)
+)
diff --git a/t/chainlint/block.test b/t/chainlint/block.test
index d859151..0a82fd5 100644
--- a/t/chainlint/block.test
+++ b/t/chainlint/block.test
@@ -1,6 +1,5 @@
 (
-# LINT: missing "&&" in block not currently detected (for consistency with
-# LINT: --chain-lint at top level and to provide escape hatch if needed)
+# LINT: missing "&&" after first "echo"
 	foo &&
 	{
 		echo a
diff --git a/t/chainlint/broken-chain.expect b/t/chainlint/broken-chain.expect
index 55b0f42..cfb58fb 100644
--- a/t/chainlint/broken-chain.expect
+++ b/t/chainlint/broken-chain.expect
@@ -1,6 +1,6 @@
 (
 	foo &&
-?!AMP?!	bar
+	bar ?!AMP?!
 	baz &&
 	wop
->)
+)
diff --git a/t/chainlint/broken-chain.test b/t/chainlint/broken-chain.test
index 3cc67b6..2a44aa7 100644
--- a/t/chainlint/broken-chain.test
+++ b/t/chainlint/broken-chain.test
@@ -1,6 +1,6 @@
 (
 	foo &&
-# LINT: missing "&&" from 'bar'
+# LINT: missing "&&" from "bar"
 	bar
 	baz &&
 # LINT: final statement before closing ")" legitimately lacks "&&"
diff --git a/t/chainlint/case-comment.expect b/t/chainlint/case-comment.expect
new file mode 100644
index 0000000..1e4b054
--- /dev/null
+++ b/t/chainlint/case-comment.expect
@@ -0,0 +1,8 @@
+(
+	case "$x" in
+	x) foo ;;
+	*)
+		bar
+		;;
+	esac
+)
diff --git a/t/chainlint/case-comment.test b/t/chainlint/case-comment.test
new file mode 100644
index 0000000..641c157
--- /dev/null
+++ b/t/chainlint/case-comment.test
@@ -0,0 +1,11 @@
+(
+	case "$x" in
+	# found foo
+	x) foo ;;
+	# found other
+	*)
+		# treat it as bar
+		bar
+		;;
+	esac
+)
diff --git a/t/chainlint/case.expect b/t/chainlint/case.expect
index 41f121f..31f280d 100644
--- a/t/chainlint/case.expect
+++ b/t/chainlint/case.expect
@@ -4,16 +4,16 @@
 	*) bar ;;
 	esac &&
 	foobar
->) &&
+) &&
 (
 	case "$x" in
 	x) foo ;;
 	*) bar ;;
-?!AMP?!	esac
+	esac ?!AMP?!
 	foobar
->) &&
+) &&
 (
 	case "$x" in 1) true;; esac &&
-?!AMP?!	case "$y" in 2) false;; esac
+	case "$y" in 2) false;; esac ?!AMP?!
 	foobar
->)
+)
diff --git a/t/chainlint/case.test b/t/chainlint/case.test
index 5ef6ff7..4cb086b 100644
--- a/t/chainlint/case.test
+++ b/t/chainlint/case.test
@@ -1,5 +1,5 @@
 (
-# LINT: "...)" arms in 'case' not misinterpreted as subshell-closing ")"
+# LINT: "...)" arms in "case" not misinterpreted as subshell-closing ")"
 	case "$x" in
 	x) foo ;;
 	*) bar ;;
@@ -7,7 +7,7 @@
 	foobar
 ) &&
 (
-# LINT: missing "&&" on 'esac'
+# LINT: missing "&&" on "esac"
 	case "$x" in
 	x) foo ;;
 	*) bar ;;
@@ -15,7 +15,7 @@
 	foobar
 ) &&
 (
-# LINT: "...)" arm in one-liner 'case' not misinterpreted as closing ")"
+# LINT: "...)" arm in one-liner "case" not misinterpreted as closing ")"
 	case "$x" in 1) true;; esac &&
 # LINT: same but missing "&&"
 	case "$y" in 2) false;; esac
diff --git a/t/chainlint/close-nested-and-parent-together.expect b/t/chainlint/close-nested-and-parent-together.expect
index 2a910f9..72d482f 100644
--- a/t/chainlint/close-nested-and-parent-together.expect
+++ b/t/chainlint/close-nested-and-parent-together.expect
@@ -1,4 +1,3 @@
-(
-cd foo &&
+(cd foo &&
 	(bar &&
->>>		baz))
+		baz))
diff --git a/t/chainlint/close-subshell.expect b/t/chainlint/close-subshell.expect
index 1846887..0f87db9 100644
--- a/t/chainlint/close-subshell.expect
+++ b/t/chainlint/close-subshell.expect
@@ -1,25 +1,25 @@
 (
 	foo
->) &&
+) &&
 (
 	bar
->) >out &&
+) >out &&
 (
 	baz
->) 2>err &&
+) 2>err &&
 (
 	boo
->) <input &&
+) <input &&
 (
 	bip
->) | wuzzle &&
+) | wuzzle &&
 (
 	bop
->) | fazz 	fozz &&
+) | fazz 	fozz &&
 (
 	bup
->) |
+) |
 fuzzle &&
 (
 	yop
->)
+)
diff --git a/t/chainlint/command-substitution.expect b/t/chainlint/command-substitution.expect
index ad4118e..c72e4df 100644
--- a/t/chainlint/command-substitution.expect
+++ b/t/chainlint/command-substitution.expect
@@ -2,8 +2,8 @@
 	foo &&
 	bar=$(gobble) &&
 	baz
->) &&
+) &&
 (
-?!AMP?!	bar=$(gobble blocks)
+	bar=$(gobble blocks) ?!AMP?!
 	baz
->)
+)
diff --git a/t/chainlint/comment.expect b/t/chainlint/comment.expect
index 3be939e..f76fde1 100644
--- a/t/chainlint/comment.expect
+++ b/t/chainlint/comment.expect
@@ -1,4 +1,4 @@
 (
 	nothing &&
 	something
->)
+)
diff --git a/t/chainlint/complex-if-in-cuddled-loop.expect b/t/chainlint/complex-if-in-cuddled-loop.expect
index 9674b88..2fca183 100644
--- a/t/chainlint/complex-if-in-cuddled-loop.expect
+++ b/t/chainlint/complex-if-in-cuddled-loop.expect
@@ -1,10 +1,9 @@
-(
-for i in a b c; do
+(for i in a b c; do
    if test "$(echo $(waffle bat))" = "eleventeen" &&
      test "$x" = "$y"; then
      :
    else
      echo >file
    fi
-> done) &&
+ done) &&
 test ! -f file
diff --git a/t/chainlint/complex-if-in-cuddled-loop.test b/t/chainlint/complex-if-in-cuddled-loop.test
index 571bbd8..5efeda5 100644
--- a/t/chainlint/complex-if-in-cuddled-loop.test
+++ b/t/chainlint/complex-if-in-cuddled-loop.test
@@ -1,4 +1,4 @@
-# LINT: 'for' loop cuddled with "(" and ")" and nested 'if' with complex
+# LINT: "for" loop cuddled with "(" and ")" and nested "if" with complex
 # LINT: multi-line condition; indented with spaces, not tabs
 (for i in a b c; do
    if test "$(echo $(waffle bat))" = "eleventeen" &&
diff --git a/t/chainlint/cuddled-if-then-else.expect b/t/chainlint/cuddled-if-then-else.expect
index ab2a026..1d8ed58 100644
--- a/t/chainlint/cuddled-if-then-else.expect
+++ b/t/chainlint/cuddled-if-then-else.expect
@@ -1,7 +1,6 @@
-(
-if test -z ""; then
+(if test -z ""; then
     echo empty
  else
     echo bizzy
-> fi) &&
+ fi) &&
 echo foobar
diff --git a/t/chainlint/cuddled-if-then-else.test b/t/chainlint/cuddled-if-then-else.test
index eed774a..7c53f4e 100644
--- a/t/chainlint/cuddled-if-then-else.test
+++ b/t/chainlint/cuddled-if-then-else.test
@@ -1,4 +1,4 @@
-# LINT: 'if' cuddled with "(" and ")"; indented with spaces, not tabs
+# LINT: "if" cuddled with "(" and ")"; indented with spaces, not tabs
 (if test -z ""; then
     echo empty
  else
diff --git a/t/chainlint/cuddled-loop.expect b/t/chainlint/cuddled-loop.expect
index 8c0260d..9cf2607 100644
--- a/t/chainlint/cuddled-loop.expect
+++ b/t/chainlint/cuddled-loop.expect
@@ -1,5 +1,4 @@
-(
- while read x
+( while read x
   do foobar bop || exit 1
->  done <file ) &&
+  done <file ) &&
 outside subshell
diff --git a/t/chainlint/cuddled-loop.test b/t/chainlint/cuddled-loop.test
index a841d78..3c2a62f 100644
--- a/t/chainlint/cuddled-loop.test
+++ b/t/chainlint/cuddled-loop.test
@@ -1,4 +1,4 @@
-# LINT: 'while' loop cuddled with "(" and ")", with embedded (allowed)
+# LINT: "while" loop cuddled with "(" and ")", with embedded (allowed)
 # LINT: "|| exit {n}" to exit loop early, and using redirection "<" to feed
 # LINT: loop; indented with spaces, not tabs
 ( while read x
diff --git a/t/chainlint/cuddled.expect b/t/chainlint/cuddled.expect
index b506d46..c3e0be4 100644
--- a/t/chainlint/cuddled.expect
+++ b/t/chainlint/cuddled.expect
@@ -1,21 +1,17 @@
-(
-cd foo &&
+(cd foo &&
 	bar
->) &&
+) &&
 
-(
-?!AMP?!cd foo
+(cd foo ?!AMP?!
 	bar
->) &&
+) &&
 
 (
 	cd foo &&
->	bar) &&
+	bar) &&
 
-(
-cd foo &&
->	bar) &&
+(cd foo &&
+	bar) &&
 
-(
-?!AMP?!cd foo
->	bar)
+(cd foo ?!AMP?!
+	bar)
diff --git a/t/chainlint/cuddled.test b/t/chainlint/cuddled.test
index 0499fa4..257b5b5 100644
--- a/t/chainlint/cuddled.test
+++ b/t/chainlint/cuddled.test
@@ -1,5 +1,4 @@
-# LINT: first subshell statement cuddled with opening "("; for implementation
-# LINT: simplicity, "(..." is split into two lines, "(" and "..."
+# LINT: first subshell statement cuddled with opening "("
 (cd foo &&
 	bar
 ) &&
diff --git a/t/chainlint/exit-loop.expect b/t/chainlint/exit-loop.expect
index 84d8bde..f76aa60 100644
--- a/t/chainlint/exit-loop.expect
+++ b/t/chainlint/exit-loop.expect
@@ -5,7 +5,7 @@
 		bar &&
 		baz
 	done
->) &&
+) &&
 (
 	while true
 	do
@@ -13,7 +13,7 @@
 		bar &&
 		baz
 	done
->) &&
+) &&
 (
 	i=0 &&
 	while test $i -lt 10
@@ -21,4 +21,4 @@
 		echo $i || exit
 		i=$(($i + 1))
 	done
->)
+)
diff --git a/t/chainlint/exit-subshell.expect b/t/chainlint/exit-subshell.expect
index bf78454..da80339 100644
--- a/t/chainlint/exit-subshell.expect
+++ b/t/chainlint/exit-subshell.expect
@@ -2,4 +2,4 @@
 	foo || exit 1
 	bar &&
 	baz
->)
+)
diff --git a/t/chainlint/for-loop.expect b/t/chainlint/for-loop.expect
index c33cf56..6671b8c 100644
--- a/t/chainlint/for-loop.expect
+++ b/t/chainlint/for-loop.expect
@@ -1,11 +1,11 @@
 (
 	for i in a b c
 	do
-?!AMP?!		echo $i
-		cat
-?!AMP?!	done
+		echo $i ?!AMP?!
+		cat <<-EOF
+	done ?!AMP?!
 	for i in a b c; do
 		echo $i &&
 		cat $i
 	done
->)
+)
diff --git a/t/chainlint/for-loop.test b/t/chainlint/for-loop.test
index 7db7626..6cb3428 100644
--- a/t/chainlint/for-loop.test
+++ b/t/chainlint/for-loop.test
@@ -1,17 +1,17 @@
 (
-# LINT: 'for', 'do', 'done' do not need "&&"
+# LINT: "for", "do", "done" do not need "&&"
 	for i in a b c
 	do
-# LINT: missing "&&" on 'echo'
+# LINT: missing "&&" on "echo"
 		echo $i
 # LINT: last statement of while does not need "&&"
 		cat <<-\EOF
 		bar
 		EOF
-# LINT: missing "&&" on 'done'
+# LINT: missing "&&" on "done"
 	done
 
-# LINT: 'do' on same line as 'for'
+# LINT: "do" on same line as "for"
 	for i in a b c; do
 		echo $i &&
 		cat $i
diff --git a/t/chainlint/here-doc-close-subshell.expect b/t/chainlint/here-doc-close-subshell.expect
index f011e33..2af9ced 100644
--- a/t/chainlint/here-doc-close-subshell.expect
+++ b/t/chainlint/here-doc-close-subshell.expect
@@ -1,2 +1,2 @@
 (
->	cat)
+	cat <<-INPUT)
diff --git a/t/chainlint/here-doc-multi-line-command-subst.expect b/t/chainlint/here-doc-multi-line-command-subst.expect
index e5fb752..f8b3aa7 100644
--- a/t/chainlint/here-doc-multi-line-command-subst.expect
+++ b/t/chainlint/here-doc-multi-line-command-subst.expect
@@ -1,5 +1,5 @@
 (
-	x=$(bobble &&
-?!AMP?!>>		wiffle)
+	x=$(bobble <<-END &&
+		wiffle) ?!AMP?!
 	echo $x
->)
+)
diff --git a/t/chainlint/here-doc-multi-line-string.expect b/t/chainlint/here-doc-multi-line-string.expect
index 32038a0..2578191 100644
--- a/t/chainlint/here-doc-multi-line-string.expect
+++ b/t/chainlint/here-doc-multi-line-string.expect
@@ -1,4 +1,4 @@
 (
-?!AMP?!	cat && echo "multi-line	string"
+	cat <<-TXT && echo "multi-line	string" ?!AMP?!
 	bap
->)
+)
diff --git a/t/chainlint/here-doc.expect b/t/chainlint/here-doc.expect
index 534b065..110059b 100644
--- a/t/chainlint/here-doc.expect
+++ b/t/chainlint/here-doc.expect
@@ -1,9 +1,7 @@
-boodle wobba        gorgo snoot        wafta snurb &&
+boodle wobba        gorgo snoot        wafta snurb <<EOF &&
 
-cat >foo &&
+cat <<-Arbitrary_Tag_42 >foo &&
 
-cat >bar &&
+cat <<zump >boo &&
 
-cat >boo &&
-
-horticulture
+horticulture <<EOF
diff --git a/t/chainlint/here-doc.test b/t/chainlint/here-doc.test
index ad4ce8a..3f5f92c 100644
--- a/t/chainlint/here-doc.test
+++ b/t/chainlint/here-doc.test
@@ -14,13 +14,6 @@
 woz
 Arbitrary_Tag_42
 
-# LINT: swallow 'quoted' here-doc
-cat <<'FUMP' >bar &&
-snoz
-boz
-woz
-FUMP
-
 # LINT: swallow "quoted" here-doc
 cat <<"zump" >boo &&
 snoz
diff --git a/t/chainlint/if-in-loop.expect b/t/chainlint/if-in-loop.expect
index 03d3ceb..03b82a3 100644
--- a/t/chainlint/if-in-loop.expect
+++ b/t/chainlint/if-in-loop.expect
@@ -3,10 +3,10 @@
 	do
 		if false
 		then
-?!AMP?!			echo "err"
+			echo "err" ?!AMP?!
 			exit 1
-?!AMP?!		fi
+		fi ?!AMP?!
 		foo
-?!AMP?!	done
+	done ?!AMP?!
 	bar
->)
+)
diff --git a/t/chainlint/if-in-loop.test b/t/chainlint/if-in-loop.test
index daf22da..f0cf19c 100644
--- a/t/chainlint/if-in-loop.test
+++ b/t/chainlint/if-in-loop.test
@@ -3,13 +3,13 @@
 	do
 		if false
 		then
-# LINT: missing "&&" on 'echo'
+# LINT: missing "&&" on "echo"
 			echo "err"
 			exit 1
-# LINT: missing "&&" on 'fi'
+# LINT: missing "&&" on "fi"
 		fi
 		foo
-# LINT: missing "&&" on 'done'
+# LINT: missing "&&" on "done"
 	done
 	bar
 )
diff --git a/t/chainlint/if-then-else.expect b/t/chainlint/if-then-else.expect
index 5953c7b..44d86c3 100644
--- a/t/chainlint/if-then-else.expect
+++ b/t/chainlint/if-then-else.expect
@@ -1,19 +1,20 @@
 (
 	if test -n ""
 	then
-?!AMP?!		echo very
+		echo very ?!AMP?!
 		echo empty
 	elif test -z ""
+	then
 		echo foo
 	else
 		echo foo &&
-		cat
-?!AMP?!	fi
+		cat <<-EOF
+	fi ?!AMP?!
 	echo poodle
->) &&
+) &&
 (
 	if test -n ""; then
 		echo very &&
-?!AMP?!		echo empty
-	if
->)
+		echo empty
+	fi
+)
diff --git a/t/chainlint/if-then-else.test b/t/chainlint/if-then-else.test
index 9bd8e9a..2055336 100644
--- a/t/chainlint/if-then-else.test
+++ b/t/chainlint/if-then-else.test
@@ -1,28 +1,29 @@
 (
-# LINT: 'if', 'then', 'elif', 'else', 'fi' do not need "&&"
+# LINT: "if", "then", "elif", "else", "fi" do not need "&&"
 	if test -n ""
 	then
-# LINT: missing "&&" on 'echo'
+# LINT: missing "&&" on "echo"
 		echo very
-# LINT: last statement before 'elif' does not need "&&"
+# LINT: last statement before "elif" does not need "&&"
 		echo empty
 	elif test -z ""
-# LINT: last statement before 'else' does not need "&&"
+	then
+# LINT: last statement before "else" does not need "&&"
 		echo foo
 	else
 		echo foo &&
-# LINT: last statement before 'fi' does not need "&&"
+# LINT: last statement before "fi" does not need "&&"
 		cat <<-\EOF
 		bar
 		EOF
-# LINT: missing "&&" on 'fi'
+# LINT: missing "&&" on "fi"
 	fi
 	echo poodle
 ) &&
 (
-# LINT: 'then' on same line as 'if'
+# LINT: "then" on same line as "if"
 	if test -n ""; then
 		echo very &&
 		echo empty
-	if
+	fi
 )
diff --git a/t/chainlint/incomplete-line.expect b/t/chainlint/incomplete-line.expect
index 2f3ebab..ffac8f9 100644
--- a/t/chainlint/incomplete-line.expect
+++ b/t/chainlint/incomplete-line.expect
@@ -1,4 +1,4 @@
 line 1 line 2 line 3 line 4 &&
 (
 	line 5 	line 6 	line 7 	line 8
->)
+)
diff --git a/t/chainlint/inline-comment.expect b/t/chainlint/inline-comment.expect
index fc9f250..dd0dace 100644
--- a/t/chainlint/inline-comment.expect
+++ b/t/chainlint/inline-comment.expect
@@ -1,9 +1,8 @@
 (
 	foobar &&
-?!AMP?!	barfoo
+	barfoo ?!AMP?!
 	flibble "not a # comment"
->) &&
+) &&
 
-(
-cd foo &&
->	flibble "not a # comment")
+(cd foo &&
+	flibble "not a # comment")
diff --git a/t/chainlint/loop-in-if.expect b/t/chainlint/loop-in-if.expect
index 088e622..e1be423 100644
--- a/t/chainlint/loop-in-if.expect
+++ b/t/chainlint/loop-in-if.expect
@@ -3,10 +3,10 @@
 	then
 		while true
 		do
-?!AMP?!			echo "pop"
+			echo "pop" ?!AMP?!
 			echo "glup"
-?!AMP?!		done
+		done ?!AMP?!
 		foo
-?!AMP?!	fi
+	fi ?!AMP?!
 	bar
->)
+)
diff --git a/t/chainlint/loop-in-if.test b/t/chainlint/loop-in-if.test
index 93e8ba8..dfcc3f9 100644
--- a/t/chainlint/loop-in-if.test
+++ b/t/chainlint/loop-in-if.test
@@ -3,13 +3,13 @@
 	then
 		while true
 		do
-# LINT: missing "&&" on 'echo'
+# LINT: missing "&&" on "echo"
 			echo "pop"
 			echo "glup"
-# LINT: missing "&&" on 'done'
+# LINT: missing "&&" on "done"
 		done
 		foo
-# LINT: missing "&&" on 'fi'
+# LINT: missing "&&" on "fi"
 	fi
 	bar
 )
diff --git a/t/chainlint/multi-line-nested-command-substitution.expect b/t/chainlint/multi-line-nested-command-substitution.expect
index 59b6c8b..3000583 100644
--- a/t/chainlint/multi-line-nested-command-substitution.expect
+++ b/t/chainlint/multi-line-nested-command-substitution.expect
@@ -3,16 +3,16 @@
 	x=$(
 		echo bar |
 		cat
->>	) &&
+	) &&
 	echo ok
->) |
+) |
 sort &&
 (
 	bar &&
 	x=$(echo bar |
 		cat
->>	) &&
+	) &&
 	y=$(echo baz |
->>		fip) &&
+		fip) &&
 	echo fail
->)
+)
diff --git a/t/chainlint/multi-line-string.expect b/t/chainlint/multi-line-string.expect
index 170cb59..ab0dadf 100644
--- a/t/chainlint/multi-line-string.expect
+++ b/t/chainlint/multi-line-string.expect
@@ -1,15 +1,9 @@
 (
 	x="line 1		line 2		line 3" &&
-?!AMP?!	y='line 1		line2'
+	y="line 1		line2" ?!AMP?!
 	foobar
->) &&
-(
-	echo "there's nothing to see here" &&
-	exit
->) &&
+) &&
 (
 	echo "xyz" "abc		def		ghi" &&
-	echo 'xyz' 'abc		def		ghi' &&
-	echo 'xyz' "abc		def		ghi" &&
 	barfoo
->)
+)
diff --git a/t/chainlint/multi-line-string.test b/t/chainlint/multi-line-string.test
index 287ab89..4a0af21 100644
--- a/t/chainlint/multi-line-string.test
+++ b/t/chainlint/multi-line-string.test
@@ -3,25 +3,13 @@
 		line 2
 		line 3" &&
 # LINT: missing "&&" on assignment
-	y='line 1
-		line2'
+	y="line 1
+		line2"
 	foobar
 ) &&
 (
-# LINT: apostrophe (in a contraction) within string not misinterpreted as
-# LINT: starting multi-line single-quoted string
-	echo "there's nothing to see here" &&
-	exit
-) &&
-(
 	echo "xyz" "abc
 		def
 		ghi" &&
-	echo 'xyz' 'abc
-		def
-		ghi' &&
-	echo 'xyz' "abc
-		def
-		ghi" &&
 	barfoo
 )
diff --git a/t/chainlint/negated-one-liner.expect b/t/chainlint/negated-one-liner.expect
index cf18429..ad4c2d9 100644
--- a/t/chainlint/negated-one-liner.expect
+++ b/t/chainlint/negated-one-liner.expect
@@ -1,5 +1,5 @@
 ! (foo && bar) &&
 ! (foo && bar) >baz &&
 
-?!SEMI?!! (foo; bar) &&
-?!SEMI?!! (foo; bar) >baz
+! (foo; ?!AMP?! bar) &&
+! (foo; ?!AMP?! bar) >baz
diff --git a/t/chainlint/nested-cuddled-subshell.expect b/t/chainlint/nested-cuddled-subshell.expect
index c2a59ff..2a86885 100644
--- a/t/chainlint/nested-cuddled-subshell.expect
+++ b/t/chainlint/nested-cuddled-subshell.expect
@@ -1,19 +1,19 @@
 (
 	(cd foo &&
 		bar
->>	) &&
+	) &&
 	(cd foo &&
 		bar
-?!AMP?!>>	)
+	) ?!AMP?!
 	(
 		cd foo &&
->>		bar) &&
+		bar) &&
 	(
 		cd foo &&
-?!AMP?!>>		bar)
+		bar) ?!AMP?!
 	(cd foo &&
->>		bar) &&
+		bar) &&
 	(cd foo &&
-?!AMP?!>>		bar)
+		bar) ?!AMP?!
 	foobar
->)
+)
diff --git a/t/chainlint/nested-here-doc.expect b/t/chainlint/nested-here-doc.expect
index 0c9ef1c..e3bef63 100644
--- a/t/chainlint/nested-here-doc.expect
+++ b/t/chainlint/nested-here-doc.expect
@@ -1,7 +1,7 @@
-cat >foop &&
+cat <<ARBITRARY >foop &&
 
 (
-	cat &&
-?!AMP?!	cat
+	cat <<-INPUT_END &&
+	cat <<-EOT ?!AMP?!
 	foobar
->)
+)
diff --git a/t/chainlint/nested-subshell-comment.expect b/t/chainlint/nested-subshell-comment.expect
index 15b68d4..be4b27a 100644
--- a/t/chainlint/nested-subshell-comment.expect
+++ b/t/chainlint/nested-subshell-comment.expect
@@ -2,10 +2,8 @@
 	foo &&
 	(
 		bar &&
-		# bottles wobble while fiddles gobble
-		# minor numbers of cows (or do they?)
 		baz &&
 		snaff
-?!AMP?!>>	)
+	) ?!AMP?!
 	fuzzy
->)
+)
diff --git a/t/chainlint/nested-subshell-comment.test b/t/chainlint/nested-subshell-comment.test
index 0ff136a..0215cdb 100644
--- a/t/chainlint/nested-subshell-comment.test
+++ b/t/chainlint/nested-subshell-comment.test
@@ -7,7 +7,7 @@
 		# minor numbers of cows (or do they?)
 		baz &&
 		snaff
-# LINT: missing "&&" on ')'
+# LINT: missing "&&" on ")"
 	)
 	fuzzy
 )
diff --git a/t/chainlint/nested-subshell.expect b/t/chainlint/nested-subshell.expect
index c8165ad..41a48ad 100644
--- a/t/chainlint/nested-subshell.expect
+++ b/t/chainlint/nested-subshell.expect
@@ -3,10 +3,10 @@
 	(
 		echo a &&
 		echo b
->>	) >file &&
+	) >file &&
 	cd foo &&
 	(
 		echo a
 		echo b
->>	) >file
->)
+	) >file
+)
diff --git a/t/chainlint/nested-subshell.test b/t/chainlint/nested-subshell.test
index 998b05a..440ee99 100644
--- a/t/chainlint/nested-subshell.test
+++ b/t/chainlint/nested-subshell.test
@@ -7,7 +7,6 @@
 
 	cd foo &&
 	(
-# LINT: nested multi-line subshell not presently checked for missing "&&"
 		echo a
 		echo b
 	) >file
diff --git a/t/chainlint/not-heredoc.expect b/t/chainlint/not-heredoc.expect
new file mode 100644
index 0000000..2e9bb13
--- /dev/null
+++ b/t/chainlint/not-heredoc.expect
@@ -0,0 +1,14 @@
+echo "<<<<<<< ours" &&
+echo ourside &&
+echo "=======" &&
+echo theirside &&
+echo ">>>>>>> theirs" &&
+
+(
+	echo "<<<<<<< ours" &&
+	echo ourside &&
+	echo "=======" &&
+	echo theirside &&
+	echo ">>>>>>> theirs" ?!AMP?!
+	poodle
+) >merged
diff --git a/t/chainlint/not-heredoc.test b/t/chainlint/not-heredoc.test
new file mode 100644
index 0000000..9aa5734
--- /dev/null
+++ b/t/chainlint/not-heredoc.test
@@ -0,0 +1,16 @@
+# LINT: "<< ours" inside string is not here-doc
+echo "<<<<<<< ours" &&
+echo ourside &&
+echo "=======" &&
+echo theirside &&
+echo ">>>>>>> theirs" &&
+
+(
+# LINT: "<< ours" inside string is not here-doc
+	echo "<<<<<<< ours" &&
+	echo ourside &&
+	echo "=======" &&
+	echo theirside &&
+	echo ">>>>>>> theirs"
+	poodle
+) >merged
diff --git a/t/chainlint/one-liner.expect b/t/chainlint/one-liner.expect
index 237f227..57a7a44 100644
--- a/t/chainlint/one-liner.expect
+++ b/t/chainlint/one-liner.expect
@@ -2,8 +2,8 @@
 (foo && bar) |
 (foo && bar) >baz &&
 
-?!SEMI?!(foo; bar) &&
-?!SEMI?!(foo; bar) |
-?!SEMI?!(foo; bar) >baz
+(foo; ?!AMP?! bar) &&
+(foo; ?!AMP?! bar) |
+(foo; ?!AMP?! bar) >baz &&
 
 (foo "bar; baz")
diff --git a/t/chainlint/one-liner.test b/t/chainlint/one-liner.test
index ec9acb9..be9858f 100644
--- a/t/chainlint/one-liner.test
+++ b/t/chainlint/one-liner.test
@@ -3,10 +3,10 @@
 (foo && bar) |
 (foo && bar) >baz &&
 
-# LINT: top-level one-liner subshell missing internal "&&"
+# LINT: top-level one-liner subshell missing internal "&&" and broken &&-chain
 (foo; bar) &&
 (foo; bar) |
-(foo; bar) >baz
+(foo; bar) >baz &&
 
 # LINT: ";" in string not misinterpreted as broken &&-chain
 (foo "bar; baz")
diff --git a/t/chainlint/p4-filespec.expect b/t/chainlint/p4-filespec.expect
index 98b3d88..1290fd1 100644
--- a/t/chainlint/p4-filespec.expect
+++ b/t/chainlint/p4-filespec.expect
@@ -1,4 +1,4 @@
 (
 	p4 print -1 //depot/fiddle#42 >file &&
 	foobar
->)
+)
diff --git a/t/chainlint/pipe.expect b/t/chainlint/pipe.expect
index 211b901..2cfc028 100644
--- a/t/chainlint/pipe.expect
+++ b/t/chainlint/pipe.expect
@@ -3,6 +3,6 @@
 	bar |
 	baz &&
 	fish |
-?!AMP?!	cow
+	cow ?!AMP?!
 	sunder
->)
+)
diff --git a/t/chainlint/pipe.test b/t/chainlint/pipe.test
index e6af4de..dd82534 100644
--- a/t/chainlint/pipe.test
+++ b/t/chainlint/pipe.test
@@ -4,7 +4,7 @@
 	bar |
 	baz &&
 
-# LINT: final line of pipe sequence ('cow') lacking "&&"
+# LINT: final line of pipe sequence ("cow") lacking "&&"
 	fish |
 	cow
 
diff --git a/t/chainlint/semicolon.expect b/t/chainlint/semicolon.expect
index 1d79384..ed0b370 100644
--- a/t/chainlint/semicolon.expect
+++ b/t/chainlint/semicolon.expect
@@ -1,20 +1,19 @@
 (
-?!AMP?!?!SEMI?!	cat foo ; echo bar
-?!SEMI?!	cat foo ; echo bar
->) &&
+	cat foo ; ?!AMP?! echo bar ?!AMP?!
+	cat foo ; ?!AMP?! echo bar
+) &&
 (
-?!SEMI?!	cat foo ; echo bar &&
-?!SEMI?!	cat foo ; echo bar
->) &&
+	cat foo ; ?!AMP?! echo bar &&
+	cat foo ; ?!AMP?! echo bar
+) &&
 (
 	echo "foo; bar" &&
-?!SEMI?!	cat foo; echo bar
->) &&
+	cat foo; ?!AMP?! echo bar
+) &&
 (
-?!SEMI?!	foo;
->) &&
-(
-cd foo &&
+	foo;
+) &&
+(cd foo &&
 	for i in a b c; do
-?!SEMI?!		echo;
->	done)
+		echo;
+	done)
diff --git a/t/chainlint/semicolon.test b/t/chainlint/semicolon.test
index d82c8eb..67e1192 100644
--- a/t/chainlint/semicolon.test
+++ b/t/chainlint/semicolon.test
@@ -15,11 +15,11 @@
 	cat foo; echo bar
 ) &&
 (
-# LINT: unnecessary terminating semicolon
+# LINT: semicolon unnecessary but legitimate
 	foo;
 ) &&
 (cd foo &&
 	for i in a b c; do
-# LINT: unnecessary terminating semicolon
+# LINT: semicolon unnecessary but legitimate
 		echo;
 	done)
diff --git a/t/chainlint/subshell-here-doc.expect b/t/chainlint/subshell-here-doc.expect
index 74723e7..029d129 100644
--- a/t/chainlint/subshell-here-doc.expect
+++ b/t/chainlint/subshell-here-doc.expect
@@ -1,11 +1,10 @@
 (
-	echo wobba 	       gorgo snoot 	       wafta snurb &&
-?!AMP?!	cat >bip
-	echo >bop
->) &&
+	echo wobba 	       gorgo snoot 	       wafta snurb <<-EOF &&
+	cat <<EOF >bip ?!AMP?!
+	echo <<-EOF >bop
+) &&
 (
-	cat >bup &&
-	cat >bup2 &&
-	cat >bup3 &&
+	cat <<-ARBITRARY >bup &&
+	cat <<-ARBITRARY3 >bup3 &&
 	meep
->)
+)
diff --git a/t/chainlint/subshell-here-doc.test b/t/chainlint/subshell-here-doc.test
index f6b3ba4..d40eb65 100644
--- a/t/chainlint/subshell-here-doc.test
+++ b/t/chainlint/subshell-here-doc.test
@@ -8,10 +8,10 @@
 	nevermore...
 	EOF
 
-# LINT: missing "&&" on 'cat'
+# LINT: missing "&&" on "cat"
 	cat <<EOF >bip
 	fish fly high
-	EOF
+EOF
 
 # LINT: swallow here-doc (EOF is last line of subshell)
 	echo <<-\EOF >bop
@@ -27,10 +27,6 @@
 	glink
 	FIZZ
 	ARBITRARY
-	cat <<-'ARBITRARY2' >bup2 &&
-	glink
-	FIZZ
-	ARBITRARY2
 	cat <<-"ARBITRARY3" >bup3 &&
 	glink
 	FIZZ
diff --git a/t/chainlint/subshell-one-liner.expect b/t/chainlint/subshell-one-liner.expect
index 5116282..b701536 100644
--- a/t/chainlint/subshell-one-liner.expect
+++ b/t/chainlint/subshell-one-liner.expect
@@ -2,13 +2,13 @@
 	(foo && bar) &&
 	(foo && bar) |
 	(foo && bar) >baz &&
-?!SEMI?!	(foo; bar) &&
-?!SEMI?!	(foo; bar) |
-?!SEMI?!	(foo; bar) >baz &&
+	(foo; ?!AMP?! bar) &&
+	(foo; ?!AMP?! bar) |
+	(foo; ?!AMP?! bar) >baz &&
 	(foo || exit 1) &&
 	(foo || exit 1) |
 	(foo || exit 1) >baz &&
-?!AMP?!	(foo && bar)
-?!AMP?!?!SEMI?!	(foo && bar; baz)
+	(foo && bar) ?!AMP?!
+	(foo && bar; ?!AMP?! baz) ?!AMP?!
 	foobar
->)
+)
diff --git a/t/chainlint/t7900-subtree.expect b/t/chainlint/t7900-subtree.expect
index c991342..1cccc7b 100644
--- a/t/chainlint/t7900-subtree.expect
+++ b/t/chainlint/t7900-subtree.expect
@@ -1,10 +1,10 @@
 (
 	chks="sub1sub2sub3sub4" &&
-	chks_sub=$(cat | sed 's,^,sub dir/,'
->>) &&
+	chks_sub=$(cat <<TXT | sed "s,^,sub dir/,"
+) &&
 	chkms="main-sub1main-sub2main-sub3main-sub4" &&
-	chkms_sub=$(cat | sed 's,^,sub dir/,'
->>) &&
+	chkms_sub=$(cat <<TXT | sed "s,^,sub dir/,"
+) &&
 	subfiles=$(git ls-files) &&
 	check_equal "$subfiles" "$chkms$chks"
->)
+)
diff --git a/t/chainlint/t7900-subtree.test b/t/chainlint/t7900-subtree.test
index 277d835..02f3129 100644
--- a/t/chainlint/t7900-subtree.test
+++ b/t/chainlint/t7900-subtree.test
@@ -3,7 +3,7 @@
 sub2
 sub3
 sub4" &&
-	chks_sub=$(cat <<TXT | sed 's,^,sub dir/,'
+	chks_sub=$(cat <<TXT | sed "s,^,sub dir/,"
 $chks
 TXT
 ) &&
@@ -11,7 +11,7 @@
 main-sub2
 main-sub3
 main-sub4" &&
-	chkms_sub=$(cat <<TXT | sed 's,^,sub dir/,'
+	chkms_sub=$(cat <<TXT | sed "s,^,sub dir/,"
 $chkms
 TXT
 ) &&
diff --git a/t/chainlint/while-loop.expect b/t/chainlint/while-loop.expect
index 13cff2c..0d3a9b3 100644
--- a/t/chainlint/while-loop.expect
+++ b/t/chainlint/while-loop.expect
@@ -1,11 +1,11 @@
 (
 	while true
 	do
-?!AMP?!		echo foo
-		cat
-?!AMP?!	done
+		echo foo ?!AMP?!
+		cat <<-EOF
+	done ?!AMP?!
 	while true; do
 		echo foo &&
 		cat bar
 	done
->)
+)
diff --git a/t/chainlint/while-loop.test b/t/chainlint/while-loop.test
index f1df085..d09fb01 100644
--- a/t/chainlint/while-loop.test
+++ b/t/chainlint/while-loop.test
@@ -1,17 +1,17 @@
 (
-# LINT: 'while, 'do', 'done' do not need "&&"
+# LINT: "while", "do", "done" do not need "&&"
 	while true
 	do
-# LINT: missing "&&" on 'echo'
+# LINT: missing "&&" on "echo"
 		echo foo
 # LINT: last statement of while does not need "&&"
 		cat <<-\EOF
 		bar
 		EOF
-# LINT: missing "&&" on 'done'
+# LINT: missing "&&" on "done"
 	done
 
-# LINT: 'do' on same line as 'while'
+# LINT: "do" on same line as "while"
 	while true; do
 		echo foo &&
 		cat bar
diff --git a/t/helper/test-drop-caches.c b/t/helper/test-drop-caches.c
index 7b42784..e37396d 100644
--- a/t/helper/test-drop-caches.c
+++ b/t/helper/test-drop-caches.c
@@ -3,6 +3,7 @@
 
 #if defined(GIT_WINDOWS_NATIVE)
 #include "lazyload.h"
+#include <winnt.h>
 
 static int cmd_sync(void)
 {
@@ -86,7 +87,8 @@
 {
 	HANDLE hProcess = GetCurrentProcess();
 	HANDLE hToken;
-	DECLARE_PROC_ADDR(ntdll.dll, DWORD, NtSetSystemInformation, INT, PVOID, ULONG);
+	DECLARE_PROC_ADDR(ntdll.dll, DWORD, NTAPI, NtSetSystemInformation, INT, PVOID,
+		ULONG);
 	SYSTEM_MEMORY_LIST_COMMAND command;
 	int status;
 
diff --git a/t/helper/test-genzeros.c b/t/helper/test-genzeros.c
index 9532f5b..8ca988d 100644
--- a/t/helper/test-genzeros.c
+++ b/t/helper/test-genzeros.c
@@ -3,18 +3,31 @@
 
 int cmd__genzeros(int argc, const char **argv)
 {
-	long count;
+	/* static, so that it is NUL-initialized */
+	static const char zeros[256 * 1024];
+	intmax_t count;
+	ssize_t n;
 
 	if (argc > 2) {
 		fprintf(stderr, "usage: %s [<count>]\n", argv[0]);
 		return 1;
 	}
 
-	count = argc > 1 ? strtol(argv[1], NULL, 0) : -1L;
+	count = argc > 1 ? strtoimax(argv[1], NULL, 0) : -1;
 
-	while (count < 0 || count--) {
-		if (putchar(0) == EOF)
+	/* Writing out individual NUL bytes is slow... */
+	while (count < 0)
+		if (write(1, zeros, ARRAY_SIZE(zeros)) < 0)
 			return -1;
+
+	while (count > 0) {
+		n = write(1, zeros, count < ARRAY_SIZE(zeros) ?
+			  count : ARRAY_SIZE(zeros));
+
+		if (n < 0)
+			return -1;
+
+		count -= n;
 	}
 
 	return 0;
diff --git a/t/helper/test-read-cache.c b/t/helper/test-read-cache.c
index b52c174..b736ef1 100644
--- a/t/helper/test-read-cache.c
+++ b/t/helper/test-read-cache.c
@@ -1,82 +1,39 @@
 #include "test-tool.h"
 #include "cache.h"
 #include "config.h"
-#include "blob.h"
-#include "commit.h"
-#include "tree.h"
-#include "sparse-index.h"
-
-static void print_cache_entry(struct cache_entry *ce)
-{
-	const char *type;
-	printf("%06o ", ce->ce_mode & 0177777);
-
-	if (S_ISSPARSEDIR(ce->ce_mode))
-		type = tree_type;
-	else if (S_ISGITLINK(ce->ce_mode))
-		type = commit_type;
-	else
-		type = blob_type;
-
-	printf("%s %s\t%s\n",
-	       type,
-	       oid_to_hex(&ce->oid),
-	       ce->name);
-}
-
-static void print_cache(struct index_state *istate)
-{
-	int i;
-	for (i = 0; i < istate->cache_nr; i++)
-		print_cache_entry(istate->cache[i]);
-}
 
 int cmd__read_cache(int argc, const char **argv)
 {
-	struct repository *r = the_repository;
 	int i, cnt = 1;
 	const char *name = NULL;
-	int table = 0, expand = 0;
 
 	initialize_the_repository();
-	prepare_repo_settings(r);
-	r->settings.command_requires_full_index = 0;
 
-	for (++argv, --argc; *argv && starts_with(*argv, "--"); ++argv, --argc) {
-		if (skip_prefix(*argv, "--print-and-refresh=", &name))
-			continue;
-		if (!strcmp(*argv, "--table"))
-			table = 1;
-		else if (!strcmp(*argv, "--expand"))
-			expand = 1;
+	if (argc > 1 && skip_prefix(argv[1], "--print-and-refresh=", &name)) {
+		argc--;
+		argv++;
 	}
 
-	if (argc == 1)
-		cnt = strtol(argv[0], NULL, 0);
+	if (argc == 2)
+		cnt = strtol(argv[1], NULL, 0);
 	setup_git_directory();
 	git_config(git_default_config, NULL);
 
 	for (i = 0; i < cnt; i++) {
-		repo_read_index(r);
-
-		if (expand)
-			ensure_full_index(r->index);
-
+		read_cache();
 		if (name) {
 			int pos;
 
-			refresh_index(r->index, REFRESH_QUIET,
+			refresh_index(&the_index, REFRESH_QUIET,
 				      NULL, NULL, NULL);
-			pos = index_name_pos(r->index, name, strlen(name));
+			pos = index_name_pos(&the_index, name, strlen(name));
 			if (pos < 0)
 				die("%s not in index", name);
 			printf("%s is%s up to date\n", name,
-			       ce_uptodate(r->index->cache[pos]) ? "" : " not");
+			       ce_uptodate(the_index.cache[pos]) ? "" : " not");
 			write_file(name, "%d\n", i);
 		}
-		if (table)
-			print_cache(r->index);
-		discard_index(r->index);
+		discard_cache();
 	}
 	return 0;
 }
diff --git a/t/helper/test-read-midx.c b/t/helper/test-read-midx.c
index 9d6fa7a..27072ba 100644
--- a/t/helper/test-read-midx.c
+++ b/t/helper/test-read-midx.c
@@ -55,9 +55,10 @@
 			printf("%s %"PRIu64"\t%s\n",
 			       oid_to_hex(&oid), e.offset, e.p->pack_name);
 		}
-		return 0;
 	}
 
+	close_midx(m);
+
 	return 0;
 }
 
diff --git a/t/helper/test-ref-store.c b/t/helper/test-ref-store.c
index b314b81..3e4ddae 100644
--- a/t/helper/test-ref-store.c
+++ b/t/helper/test-ref-store.c
@@ -5,6 +5,48 @@
 #include "object-store.h"
 #include "repository.h"
 
+struct flag_definition {
+	const char *name;
+	uint64_t mask;
+};
+
+#define FLAG_DEF(x)     \
+	{               \
+#x, (x) \
+	}
+
+static unsigned int parse_flags(const char *str, struct flag_definition *defs)
+{
+	struct string_list masks = STRING_LIST_INIT_DUP;
+	int i = 0;
+	unsigned int result = 0;
+
+	if (!strcmp(str, "0"))
+		return 0;
+
+	string_list_split(&masks, str, ',', 64);
+	for (; i < masks.nr; i++) {
+		const char *name = masks.items[i].string;
+		struct flag_definition *def = defs;
+		int found = 0;
+		while (def->name) {
+			if (!strcmp(def->name, name)) {
+				result |= def->mask;
+				found = 1;
+				break;
+			}
+			def++;
+		}
+		if (!found)
+			die("unknown flag \"%s\"", name);
+	}
+
+	string_list_clear(&masks, 0);
+	return result;
+}
+
+static struct flag_definition empty_flags[] = { { NULL, 0 } };
+
 static const char *notnull(const char *arg, const char *name)
 {
 	if (!arg)
@@ -12,9 +54,10 @@
 	return arg;
 }
 
-static unsigned int arg_flags(const char *arg, const char *name)
+static unsigned int arg_flags(const char *arg, const char *name,
+			      struct flag_definition *defs)
 {
-	return atoi(notnull(arg, name));
+	return parse_flags(notnull(arg, name), defs);
 }
 
 static const char **get_store(const char **argv, struct ref_store **refs)
@@ -64,10 +107,13 @@
 	return argv + 1;
 }
 
+static struct flag_definition pack_flags[] = { FLAG_DEF(PACK_REFS_PRUNE),
+					       FLAG_DEF(PACK_REFS_ALL),
+					       { NULL, 0 } };
 
 static int cmd_pack_refs(struct ref_store *refs, const char **argv)
 {
-	unsigned int flags = arg_flags(*argv++, "flags");
+	unsigned int flags = arg_flags(*argv++, "flags", pack_flags);
 
 	return refs_pack_refs(refs, flags);
 }
@@ -81,16 +127,27 @@
 	return refs_create_symref(refs, refname, target, logmsg);
 }
 
+static struct flag_definition transaction_flags[] = {
+	FLAG_DEF(REF_NO_DEREF),
+	FLAG_DEF(REF_FORCE_CREATE_REFLOG),
+	FLAG_DEF(REF_SKIP_OID_VERIFICATION),
+	FLAG_DEF(REF_SKIP_REFNAME_VERIFICATION),
+	{ NULL, 0 }
+};
+
 static int cmd_delete_refs(struct ref_store *refs, const char **argv)
 {
-	unsigned int flags = arg_flags(*argv++, "flags");
+	unsigned int flags = arg_flags(*argv++, "flags", transaction_flags);
 	const char *msg = *argv++;
 	struct string_list refnames = STRING_LIST_INIT_NODUP;
+	int result;
 
 	while (*argv)
 		string_list_append(&refnames, *argv++);
 
-	return refs_delete_refs(refs, msg, &refnames, flags);
+	result = refs_delete_refs(refs, msg, &refnames, flags);
+	string_list_clear(&refnames, 0);
+	return result;
 }
 
 static int cmd_rename_ref(struct ref_store *refs, const char **argv)
@@ -120,12 +177,13 @@
 {
 	struct object_id oid = *null_oid();
 	const char *refname = notnull(*argv++, "refname");
-	int resolve_flags = arg_flags(*argv++, "resolve-flags");
+	int resolve_flags = arg_flags(*argv++, "resolve-flags", empty_flags);
 	int flags;
 	const char *ref;
+	int ignore_errno;
 
 	ref = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
-				      &oid, &flags);
+				      &oid, &flags, &ignore_errno);
 	printf("%s %s 0x%x\n", oid_to_hex(&oid), ref ? ref : "(null)", flags);
 	return ref ? 0 : 1;
 }
@@ -151,9 +209,9 @@
 		       const char *committer, timestamp_t timestamp,
 		       int tz, const char *msg, void *cb_data)
 {
-	printf("%s %s %s %"PRItime" %d %s\n",
-	       oid_to_hex(old_oid), oid_to_hex(new_oid),
-	       committer, timestamp, tz, msg);
+	printf("%s %s %s %" PRItime " %+05d%s%s", oid_to_hex(old_oid),
+	       oid_to_hex(new_oid), committer, timestamp, tz,
+	       *msg == '\n' ? "" : "\t", msg);
 	return 0;
 }
 
@@ -181,11 +239,10 @@
 static int cmd_create_reflog(struct ref_store *refs, const char **argv)
 {
 	const char *refname = notnull(*argv++, "refname");
-	int force_create = arg_flags(*argv++, "force-create");
 	struct strbuf err = STRBUF_INIT;
 	int ret;
 
-	ret = refs_create_reflog(refs, refname, force_create, &err);
+	ret = refs_create_reflog(refs, refname, &err);
 	if (err.len)
 		puts(err.buf);
 	return ret;
@@ -208,11 +265,11 @@
 	const char *msg = notnull(*argv++, "msg");
 	const char *refname = notnull(*argv++, "refname");
 	const char *sha1_buf = notnull(*argv++, "old-sha1");
-	unsigned int flags = arg_flags(*argv++, "flags");
+	unsigned int flags = arg_flags(*argv++, "flags", transaction_flags);
 	struct object_id old_oid;
 
 	if (get_oid_hex(sha1_buf, &old_oid))
-		die("not sha-1");
+		die("cannot parse %s as %s", sha1_buf, the_hash_algo->name);
 
 	return refs_delete_ref(refs, msg, refname, &old_oid, flags);
 }
@@ -223,13 +280,14 @@
 	const char *refname = notnull(*argv++, "refname");
 	const char *new_sha1_buf = notnull(*argv++, "new-sha1");
 	const char *old_sha1_buf = notnull(*argv++, "old-sha1");
-	unsigned int flags = arg_flags(*argv++, "flags");
+	unsigned int flags = arg_flags(*argv++, "flags", transaction_flags);
 	struct object_id old_oid;
 	struct object_id new_oid;
 
-	if (get_oid_hex(old_sha1_buf, &old_oid) ||
-	    get_oid_hex(new_sha1_buf, &new_oid))
-		die("not sha-1");
+	if (get_oid_hex(old_sha1_buf, &old_oid))
+		die("cannot parse %s as %s", old_sha1_buf, the_hash_algo->name);
+	if (get_oid_hex(new_sha1_buf, &new_oid))
+		die("cannot parse %s as %s", new_sha1_buf, the_hash_algo->name);
 
 	return refs_update_ref(refs, msg, refname,
 			       &new_oid, &old_oid,
diff --git a/t/helper/test-reftable.c b/t/helper/test-reftable.c
new file mode 100644
index 0000000..26b03d7
--- /dev/null
+++ b/t/helper/test-reftable.c
@@ -0,0 +1,21 @@
+#include "reftable/reftable-tests.h"
+#include "test-tool.h"
+
+int cmd__reftable(int argc, const char **argv)
+{
+	basics_test_main(argc, argv);
+	block_test_main(argc, argv);
+	merged_test_main(argc, argv);
+	pq_test_main(argc, argv);
+	record_test_main(argc, argv);
+	refname_test_main(argc, argv);
+	readwrite_test_main(argc, argv);
+	stack_test_main(argc, argv);
+	tree_test_main(argc, argv);
+	return 0;
+}
+
+int cmd__dump_reftable(int argc, const char **argv)
+{
+	return reftable_dump_main(argc, (char *const *)argv);
+}
diff --git a/t/helper/test-run-command.c b/t/helper/test-run-command.c
index 3c4fb86..913775a 100644
--- a/t/helper/test-run-command.c
+++ b/t/helper/test-run-command.c
@@ -31,7 +31,7 @@
 	if (number_callbacks >= 4)
 		return 0;
 
-	strvec_pushv(&cp->args, d->argv);
+	strvec_pushv(&cp->args, d->args.v);
 	strbuf_addstr(err, "preloaded output of a child\n");
 	number_callbacks++;
 	return 1;
@@ -274,7 +274,7 @@
 		if (i < skip)
 			continue;
 
-		cp.argv = args.v;
+		strvec_pushv(&cp.args, args.v);
 		strbuf_reset(&out);
 		if (pipe_command(&cp, NULL, 0, &out, 0, NULL, 0) < 0)
 			return error("Failed to spawn child process");
@@ -396,7 +396,7 @@
 	}
 	if (argc < 3)
 		return 1;
-	proc.argv = (const char **)argv + 2;
+	strvec_pushv(&proc.args, (const char **)argv + 2);
 
 	if (!strcmp(argv[1], "start-command-ENOENT")) {
 		if (start_command(&proc) < 0 && errno == ENOENT)
@@ -408,7 +408,8 @@
 		exit(run_command(&proc));
 
 	jobs = atoi(argv[2]);
-	proc.argv = (const char **)argv + 3;
+	strvec_clear(&proc.args);
+	strvec_pushv(&proc.args, (const char **)argv + 3);
 
 	if (!strcmp(argv[1], "run-command-parallel"))
 		exit(run_processes_parallel(jobs, parallel_next,
diff --git a/t/helper/test-subprocess.c b/t/helper/test-subprocess.c
index 92b69de..ff22f2f 100644
--- a/t/helper/test-subprocess.c
+++ b/t/helper/test-subprocess.c
@@ -15,6 +15,6 @@
 		argv++;
 	}
 	cp.git_cmd = 1;
-	cp.argv = (const char **)argv + 1;
+	strvec_pushv(&cp.args, (const char **)argv + 1);
 	return run_command(&cp);
 }
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index 3ce5585..338a57b 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -53,13 +53,15 @@
 	{ "pcre2-config", cmd__pcre2_config },
 	{ "pkt-line", cmd__pkt_line },
 	{ "prio-queue", cmd__prio_queue },
-	{ "proc-receive", cmd__proc_receive},
+	{ "proc-receive", cmd__proc_receive },
 	{ "progress", cmd__progress },
 	{ "reach", cmd__reach },
 	{ "read-cache", cmd__read_cache },
 	{ "read-graph", cmd__read_graph },
 	{ "read-midx", cmd__read_midx },
 	{ "ref-store", cmd__ref_store },
+	{ "reftable", cmd__reftable },
+	{ "dump-reftable", cmd__dump_reftable },
 	{ "regex", cmd__regex },
 	{ "repository", cmd__repository },
 	{ "revision-walking", cmd__revision_walking },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index 9f0f522..48cee1f 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -19,6 +19,7 @@
 int cmd__dump_fsmonitor(int argc, const char **argv);
 int cmd__dump_split_index(int argc, const char **argv);
 int cmd__dump_untracked_cache(int argc, const char **argv);
+int cmd__dump_reftable(int argc, const char **argv);
 int cmd__example_decorate(int argc, const char **argv);
 int cmd__fast_rebase(int argc, const char **argv);
 int cmd__genrandom(int argc, const char **argv);
@@ -49,6 +50,7 @@
 int cmd__read_graph(int argc, const char **argv);
 int cmd__read_midx(int argc, const char **argv);
 int cmd__ref_store(int argc, const char **argv);
+int cmd__reftable(int argc, const char **argv);
 int cmd__regex(int argc, const char **argv);
 int cmd__repository(int argc, const char **argv);
 int cmd__revision_walking(int argc, const char **argv);
diff --git a/t/helper/test-trace2.c b/t/helper/test-trace2.c
index f93633f..59b124b 100644
--- a/t/helper/test-trace2.c
+++ b/t/helper/test-trace2.c
@@ -262,8 +262,9 @@
  *    [] the "cmd_name" event has been generated.
  *    [] this writes various "def_param" events for interesting config values.
  *
- * We further assume that if we return (rather than exit()), trace2_cmd_exit()
- * will be called by test-tool.c:cmd_main().
+ * We return from here and let test-tool.c::cmd_main() pass the exit
+ * code to common-main.c::main(), which will use it to call
+ * trace2_cmd_exit().
  */
 int cmd__trace2(int argc, const char **argv)
 {
diff --git a/t/lib-gpg.sh b/t/lib-gpg.sh
index a3f285f..3e7ee13 100644
--- a/t/lib-gpg.sh
+++ b/t/lib-gpg.sh
@@ -90,7 +90,12 @@
 GPGSSH_KEY_PRIMARY="${GNUPGHOME}/ed25519_ssh_signing_key"
 GPGSSH_KEY_SECONDARY="${GNUPGHOME}/rsa_2048_ssh_signing_key"
 GPGSSH_KEY_UNTRUSTED="${GNUPGHOME}/untrusted_ssh_signing_key"
+GPGSSH_KEY_EXPIRED="${GNUPGHOME}/expired_ssh_signing_key"
+GPGSSH_KEY_NOTYETVALID="${GNUPGHOME}/notyetvalid_ssh_signing_key"
+GPGSSH_KEY_TIMEBOXEDVALID="${GNUPGHOME}/timeboxed_valid_ssh_signing_key"
+GPGSSH_KEY_TIMEBOXEDINVALID="${GNUPGHOME}/timeboxed_invalid_ssh_signing_key"
 GPGSSH_KEY_WITH_PASSPHRASE="${GNUPGHOME}/protected_ssh_signing_key"
+GPGSSH_KEY_ECDSA="${GNUPGHOME}/ecdsa_ssh_signing_key"
 GPGSSH_KEY_PASSPHRASE="super_secret"
 GPGSSH_ALLOWED_SIGNERS="${GNUPGHOME}/ssh.all_valid.allowedSignersFile"
 
@@ -105,21 +110,63 @@
 	echo $ssh_version | grep -q "find-principals:missing signature file"
 	test $? = 0 || exit 1;
 
-	# some broken versions of ssh-keygen segfault on find-principals;
-	# avoid testing with them.
-	ssh-keygen -Y find-principals -f /dev/null -s /dev/null
-	test $? = 139 && exit 1
-
+	# Setup some keys and an allowed signers file
 	mkdir -p "${GNUPGHOME}" &&
 	chmod 0700 "${GNUPGHOME}" &&
 	(setfacl -k "${GNUPGHOME}" 2>/dev/null || true) &&
 	ssh-keygen -t ed25519 -N "" -C "git ed25519 key" -f "${GPGSSH_KEY_PRIMARY}" >/dev/null &&
-	echo "\"principal with number 1\" $(cat "${GPGSSH_KEY_PRIMARY}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}" &&
 	ssh-keygen -t rsa -b 2048 -N "" -C "git rsa2048 key" -f "${GPGSSH_KEY_SECONDARY}" >/dev/null &&
-	echo "\"principal with number 2\" $(cat "${GPGSSH_KEY_SECONDARY}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}" &&
 	ssh-keygen -t ed25519 -N "${GPGSSH_KEY_PASSPHRASE}" -C "git ed25519 encrypted key" -f "${GPGSSH_KEY_WITH_PASSPHRASE}" >/dev/null &&
-	echo "\"principal with number 3\" $(cat "${GPGSSH_KEY_WITH_PASSPHRASE}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}" &&
-	ssh-keygen -t ed25519 -N "" -f "${GPGSSH_KEY_UNTRUSTED}" >/dev/null
+	ssh-keygen -t ecdsa -N "" -f "${GPGSSH_KEY_ECDSA}" >/dev/null &&
+	ssh-keygen -t ed25519 -N "" -C "git ed25519 key" -f "${GPGSSH_KEY_UNTRUSTED}" >/dev/null &&
+
+	cat >"${GPGSSH_ALLOWED_SIGNERS}" <<-EOF &&
+	"principal with number 1" $(cat "${GPGSSH_KEY_PRIMARY}.pub")"
+	"principal with number 2" $(cat "${GPGSSH_KEY_SECONDARY}.pub")"
+	"principal with number 3" $(cat "${GPGSSH_KEY_WITH_PASSPHRASE}.pub")"
+	"principal with number 4" $(cat "${GPGSSH_KEY_ECDSA}.pub")"
+	EOF
+
+	# Verify if at least one key and ssh-keygen works as expected
+	echo "testpayload" |
+	ssh-keygen -Y sign -n "git" -f "${GPGSSH_KEY_PRIMARY}" >gpgssh_prereq.sig &&
+	ssh-keygen -Y find-principals -f "${GPGSSH_ALLOWED_SIGNERS}" -s gpgssh_prereq.sig &&
+	echo "testpayload" |
+	ssh-keygen -Y verify -n "git" -f "${GPGSSH_ALLOWED_SIGNERS}" -I "principal with number 1" -s gpgssh_prereq.sig
+'
+
+test_lazy_prereq GPGSSH_VERIFYTIME '
+	# Check if ssh-keygen has a verify-time option by passing an invalid date to it
+	ssh-keygen -Overify-time=INVALID -Y check-novalidate -s doesnotmatter 2>&1 | grep -q -F "Invalid \"verify-time\"" &&
+
+	# Set up keys with key lifetimes
+	ssh-keygen -t ed25519 -N "" -C "timeboxed valid key" -f "${GPGSSH_KEY_TIMEBOXEDVALID}" >/dev/null &&
+	key_valid=$(cat "${GPGSSH_KEY_TIMEBOXEDVALID}.pub") &&
+	ssh-keygen -t ed25519 -N "" -C "timeboxed invalid key" -f "${GPGSSH_KEY_TIMEBOXEDINVALID}" >/dev/null &&
+	key_invalid=$(cat "${GPGSSH_KEY_TIMEBOXEDINVALID}.pub") &&
+	ssh-keygen -t ed25519 -N "" -C "expired key" -f "${GPGSSH_KEY_EXPIRED}" >/dev/null &&
+	key_expired=$(cat "${GPGSSH_KEY_EXPIRED}.pub") &&
+	ssh-keygen -t ed25519 -N "" -C "not yet valid key" -f "${GPGSSH_KEY_NOTYETVALID}" >/dev/null &&
+	key_notyetvalid=$(cat "${GPGSSH_KEY_NOTYETVALID}.pub") &&
+
+	# Timestamps outside of test_tick span
+	ts2005a=20050401000000 ts2005b=200504020000 &&
+	# Timestamps within test_tick span
+	ts2005c=20050407000000 ts2005d=200504100000 &&
+	# Definitely not yet valid / expired timestamps
+	ts2000=20000101000000 ts2999=29990101000000 &&
+
+	cat >>"${GPGSSH_ALLOWED_SIGNERS}" <<-EOF &&
+	"timeboxed valid key" valid-after="$ts2005c",valid-before="$ts2005d" $key_valid"
+	"timeboxed invalid key" valid-after="$ts2005a",valid-before="$ts2005b" $key_invalid"
+	"principal with expired key" valid-before="$ts2000" $key_expired"
+	"principal with not yet valid key" valid-after="$ts2999" $key_notyetvalid"
+	EOF
+
+	# and verify ssh-keygen verifies the key lifetime
+	echo "testpayload" |
+	ssh-keygen -Y sign -n "git" -f "${GPGSSH_KEY_EXPIRED}" >gpgssh_verifytime_prereq.sig &&
+	! (ssh-keygen -Y verify -n "git" -f "${GPGSSH_ALLOWED_SIGNERS}" -I "principal with expired key" -s gpgssh_verifytime_prereq.sig)
 '
 
 sanitize_pgp() {
diff --git a/t/lib-pager.sh b/t/lib-pager.sh
index 3aa7a3f..e5eb28d 100644
--- a/t/lib-pager.sh
+++ b/t/lib-pager.sh
@@ -3,7 +3,7 @@
 test_expect_success 'determine default pager' '
 	test_might_fail git config --unset core.pager &&
 	less=$(
-		unset PAGER GIT_PAGER;
+		sane_unset PAGER GIT_PAGER &&
 		git var GIT_PAGER
 	) &&
 	test -n "$less"
diff --git a/t/perf/p0005-status.sh b/t/perf/p0005-status.sh
index 0b0aa98..ca58d6c 100755
--- a/t/perf/p0005-status.sh
+++ b/t/perf/p0005-status.sh
@@ -24,17 +24,17 @@
 test_expect_success "setup repo" '
 	if git rev-parse --verify refs/heads/p0006-ballast^{commit}
 	then
-		echo Assuming synthetic repo from many-files.sh
-		git branch br_base            master
-		git branch br_ballast         p0006-ballast
-		git config --local core.sparsecheckout 1
+		echo Assuming synthetic repo from many-files.sh &&
+		git branch br_base            master &&
+		git branch br_ballast         p0006-ballast &&
+		git config --local core.sparsecheckout 1 &&
 		cat >.git/info/sparse-checkout <<-EOF
 		/*
 		!ballast/*
 		EOF
 	else
-		echo Assuming non-synthetic repo...
-		git branch br_base            $(git rev-list HEAD | tail -n 1)
+		echo Assuming non-synthetic repo... &&
+		git branch br_base            $(git rev-list HEAD | tail -n 1) &&
 		git branch br_ballast         HEAD
 	fi &&
 	git checkout -q br_ballast &&
diff --git a/t/perf/p0006-read-tree-checkout.sh b/t/perf/p0006-read-tree-checkout.sh
index 78cc23f..900b385 100755
--- a/t/perf/p0006-read-tree-checkout.sh
+++ b/t/perf/p0006-read-tree-checkout.sh
@@ -24,21 +24,21 @@
 test_expect_success "setup repo" '
 	if git rev-parse --verify refs/heads/p0006-ballast^{commit}
 	then
-		echo Assuming synthetic repo from many-files.sh
-		git branch br_base            master
-		git branch br_ballast         p0006-ballast^
-		git branch br_ballast_alias   p0006-ballast^
-		git branch br_ballast_plus_1  p0006-ballast
-		git config --local core.sparsecheckout 1
+		echo Assuming synthetic repo from many-files.sh &&
+		git branch br_base            master &&
+		git branch br_ballast         p0006-ballast^ &&
+		git branch br_ballast_alias   p0006-ballast^ &&
+		git branch br_ballast_plus_1  p0006-ballast &&
+		git config --local core.sparsecheckout 1 &&
 		cat >.git/info/sparse-checkout <<-EOF
 		/*
 		!ballast/*
 		EOF
 	else
-		echo Assuming non-synthetic repo...
-		git branch br_base            $(git rev-list HEAD | tail -n 1)
-		git branch br_ballast         HEAD^ || error "no ancestor commit from current head"
-		git branch br_ballast_alias   HEAD^
+		echo Assuming non-synthetic repo... &&
+		git branch br_base            $(git rev-list HEAD | tail -n 1) &&
+		git branch br_ballast         HEAD^ || error "no ancestor commit from current head" &&
+		git branch br_ballast_alias   HEAD^ &&
 		git branch br_ballast_plus_1  HEAD
 	fi &&
 	git checkout -q br_ballast &&
diff --git a/t/perf/p0007-write-cache.sh b/t/perf/p0007-write-cache.sh
index 0959526..25d8ff7 100755
--- a/t/perf/p0007-write-cache.sh
+++ b/t/perf/p0007-write-cache.sh
@@ -9,8 +9,8 @@
 test_expect_success "setup repo" '
 	if git rev-parse --verify refs/heads/p0006-ballast^{commit}
 	then
-		echo Assuming synthetic repo from many-files.sh
-		git config --local core.sparsecheckout 1
+		echo Assuming synthetic repo from many-files.sh &&
+		git config --local core.sparsecheckout 1 &&
 		cat >.git/info/sparse-checkout <<-EOF
 		/*
 		!ballast/*
diff --git a/t/perf/p0100-globbing.sh b/t/perf/p0100-globbing.sh
index dd18a9c..439e9c8 100755
--- a/t/perf/p0100-globbing.sh
+++ b/t/perf/p0100-globbing.sh
@@ -19,9 +19,9 @@
 		printf "a" >>refname &&
 		for j in $(test_seq 1 $i)
 		do
-			printf "a*" >>refglob.$i
+			printf "a*" >>refglob.$i || return 1
 		done &&
-		echo b >>refglob.$i
+		echo b >>refglob.$i || return 1
 	done &&
 	test_commit test $(cat refname).t "" $(cat refname).t
 '
diff --git a/t/perf/p1400-update-ref.sh b/t/perf/p1400-update-ref.sh
index dda8a74..a75969c 100755
--- a/t/perf/p1400-update-ref.sh
+++ b/t/perf/p1400-update-ref.sh
@@ -13,7 +13,7 @@
 	do
 		printf "start\ncreate refs/heads/%d PRE\ncommit\n" $i &&
 		printf "start\nupdate refs/heads/%d POST PRE\ncommit\n" $i &&
-		printf "start\ndelete refs/heads/%d POST\ncommit\n" $i
+		printf "start\ndelete refs/heads/%d POST\ncommit\n" $i || return 1
 	done >instructions
 '
 
@@ -22,7 +22,7 @@
 	do
 		git update-ref refs/heads/branch PRE &&
 		git update-ref refs/heads/branch POST PRE &&
-		git update-ref -d refs/heads/branch
+		git update-ref -d refs/heads/branch || return 1
 	done
 '
 
diff --git a/t/perf/p1451-fsck-skip-list.sh b/t/perf/p1451-fsck-skip-list.sh
index c2b97d2..f767d83 100755
--- a/t/perf/p1451-fsck-skip-list.sh
+++ b/t/perf/p1451-fsck-skip-list.sh
@@ -15,7 +15,7 @@
 		echo "committer C <c@example.com> 1234567890 +0000" &&
 		echo "data <<EOF" &&
 		echo "$i.Q." &&
-		echo "EOF"
+		echo "EOF" || return 1
 	done | q_to_nul | git fast-import
 '
 
diff --git a/t/perf/p2000-sparse-operations.sh b/t/perf/p2000-sparse-operations.sh
index 5976262..cb777c7 100755
--- a/t/perf/p2000-sparse-operations.sh
+++ b/t/perf/p2000-sparse-operations.sh
@@ -110,5 +110,12 @@
 test_perf_on_all git add .
 test_perf_on_all git commit -a -m A
 test_perf_on_all git checkout -f -
+test_perf_on_all git reset
+test_perf_on_all git reset --hard
+test_perf_on_all git reset -- does-not-exist
+test_perf_on_all git diff
+test_perf_on_all git diff --cached
+test_perf_on_all git blame $SPARSE_CONE/a
+test_perf_on_all git blame $SPARSE_CONE/f3/a
 
 test_done
diff --git a/t/perf/p3400-rebase.sh b/t/perf/p3400-rebase.sh
index 43d5a34..e6b0277 100755
--- a/t/perf/p3400-rebase.sh
+++ b/t/perf/p3400-rebase.sh
@@ -22,7 +22,7 @@
 		git add unrelated-file$i &&
 		test_tick &&
 		git commit -m commit$i-reverse unrelated-file$i ||
-		break
+		return 1
 	done &&
 	git checkout to-rebase &&
 	test_commit our-patch interesting-file
diff --git a/t/perf/p4002-diff-color-moved.sh b/t/perf/p4002-diff-color-moved.sh
new file mode 100755
index 0000000..ab2af93
--- /dev/null
+++ b/t/perf/p4002-diff-color-moved.sh
@@ -0,0 +1,57 @@
+#!/bin/sh
+
+test_description='Tests diff --color-moved performance'
+. ./perf-lib.sh
+
+test_perf_default_repo
+
+# The endpoints of the diff can be customized by setting TEST_REV_A
+# and TEST_REV_B in the environment when running this test.
+
+rev="${TEST_REV_A:-v2.28.0}"
+if ! rev_a="$(git rev-parse --quiet --verify "$rev")"
+then
+	skip_all="skipping because '$rev' was not found. \
+		  Use TEST_REV_A and TEST_REV_B to set the revs to use"
+	test_done
+fi
+rev="${TEST_REV_B:-v2.29.0}"
+if ! rev_b="$(git rev-parse --quiet --verify "$rev")"
+then
+	skip_all="skipping because '$rev' was not found. \
+		  Use TEST_REV_A and TEST_REV_B to set the revs to use"
+	test_done
+fi
+
+GIT_PAGER_IN_USE=1
+test_export GIT_PAGER_IN_USE rev_a rev_b
+
+test_perf 'diff --no-color-moved --no-color-moved-ws large change' '
+	git diff --no-color-moved --no-color-moved-ws $rev_a $rev_b
+'
+
+test_perf 'diff --color-moved --no-color-moved-ws large change' '
+	git diff --color-moved=zebra --no-color-moved-ws $rev_a $rev_b
+'
+
+test_perf 'diff --color-moved-ws=allow-indentation-change large change' '
+	git diff --color-moved=zebra --color-moved-ws=allow-indentation-change \
+		$rev_a $rev_b
+'
+
+test_perf 'log --no-color-moved --no-color-moved-ws' '
+	git log --no-color-moved --no-color-moved-ws --no-merges --patch \
+		-n1000 $rev_b
+'
+
+test_perf 'log --color-moved --no-color-moved-ws' '
+	git log --color-moved=zebra --no-color-moved-ws --no-merges --patch \
+		-n1000 $rev_b
+'
+
+test_perf 'log --color-moved-ws=allow-indentation-change' '
+	git log --color-moved=zebra --color-moved-ws=allow-indentation-change \
+		--no-merges --patch -n1000 $rev_b
+'
+
+test_done
diff --git a/t/perf/p5302-pack-index.sh b/t/perf/p5302-pack-index.sh
index 228593d..c16f6a3 100755
--- a/t/perf/p5302-pack-index.sh
+++ b/t/perf/p5302-pack-index.sh
@@ -21,8 +21,8 @@
 	threads= &&
 	while test $t -gt 0
 	do
-		threads="$t $threads"
-		t=$((t / 2))
+		threads="$t $threads" &&
+		t=$((t / 2)) || return 1
 	done
 '
 
diff --git a/t/perf/p5303-many-packs.sh b/t/perf/p5303-many-packs.sh
index 35c0cbd..af173a7 100755
--- a/t/perf/p5303-many-packs.sh
+++ b/t/perf/p5303-many-packs.sh
@@ -126,11 +126,11 @@
 # Measure pack loading with 10,000 packs.
 test_expect_success 'generate lots of packs' '
 	for i in $(test_seq 10000); do
-		echo "blob"
-		echo "data <<EOF"
-		echo "blob $i"
-		echo "EOF"
-		echo "checkpoint"
+		echo "blob" &&
+		echo "data <<EOF" &&
+		echo "blob $i" &&
+		echo "EOF" &&
+		echo "checkpoint" || return 1
 	done |
 	git -c fastimport.unpackLimit=0 fast-import
 '
diff --git a/t/perf/p7519-fsmonitor.sh b/t/perf/p7519-fsmonitor.sh
index 5eb5044..c8be58f 100755
--- a/t/perf/p7519-fsmonitor.sh
+++ b/t/perf/p7519-fsmonitor.sh
@@ -119,10 +119,10 @@
 	fi &&
 
 	mkdir 1_file 10_files 100_files 1000_files 10000_files &&
-	for i in $(test_seq 1 10); do touch 10_files/$i; done &&
-	for i in $(test_seq 1 100); do touch 100_files/$i; done &&
-	for i in $(test_seq 1 1000); do touch 1000_files/$i; done &&
-	for i in $(test_seq 1 10000); do touch 10000_files/$i; done &&
+	for i in $(test_seq 1 10); do touch 10_files/$i || return 1; done &&
+	for i in $(test_seq 1 100); do touch 100_files/$i || return 1; done &&
+	for i in $(test_seq 1 1000); do touch 1000_files/$i || return 1; done &&
+	for i in $(test_seq 1 10000); do touch 10000_files/$i || return 1; done &&
 	git add 1_file 10_files 100_files 1000_files 10000_files &&
 	git commit -qm "Add files" &&
 
diff --git a/t/perf/perf-lib.sh b/t/perf/perf-lib.sh
index 780a740..407252b 100644
--- a/t/perf/perf-lib.sh
+++ b/t/perf/perf-lib.sh
@@ -161,7 +161,7 @@
 	test_cleanup=:
 	test_export_="test_cleanup"
 	export test_cleanup test_export_
-	"$GTIME" -f "%E %U %S" -o test_time.$i "$SHELL" -c '
+	"$GTIME" -f "%E %U %S" -o test_time.$i "$TEST_SHELL_PATH" -c '
 . '"$TEST_DIRECTORY"/test-lib-functions.sh'
 test_export () {
 	test_export_="$test_export_ $*"
diff --git a/t/t0001-init.sh b/t/t0001-init.sh
index 7603ad2..3235ab4 100755
--- a/t/t0001-init.sh
+++ b/t/t0001-init.sh
@@ -331,7 +331,7 @@
 
 test_expect_success 'explicit bare & --separate-git-dir incompatible' '
 	test_must_fail git init --bare --separate-git-dir goop.git bare.git 2>err &&
-	test_i18ngrep "mutually exclusive" err
+	test_i18ngrep "cannot be used together" err
 '
 
 test_expect_success 'implicit bare & --separate-git-dir incompatible' '
diff --git a/t/t0005-signals.sh b/t/t0005-signals.sh
index a5ec6a0..eba75a2 100755
--- a/t/t0005-signals.sh
+++ b/t/t0005-signals.sh
@@ -48,7 +48,7 @@
 '
 
 test_expect_success !MINGW 'a constipated git dies with SIGPIPE even if parent ignores it' '
-	OUT=$( ((trap "" PIPE; large_git; echo $? 1>&3) | :) 3>&1 ) &&
+	OUT=$( ((trap "" PIPE && large_git; echo $? 1>&3) | :) 3>&1 ) &&
 	test_match_signal 13 "$OUT"
 '
 
diff --git a/t/t0006-date.sh b/t/t0006-date.sh
index 6b757d7..7941869 100755
--- a/t/t0006-date.sh
+++ b/t/t0006-date.sh
@@ -63,6 +63,10 @@
 check_show 'format:%Y-%m-%d %H:%M:%S' "$TIME" '2016-06-15 16:13:20'
 check_show 'format-local:%Y-%m-%d %H:%M:%S' "$TIME" '2016-06-15 09:13:20' '' EST5
 
+check_show 'format:%s' '123456789 +1234' 123456789
+check_show 'format:%s' '123456789 -1234' 123456789
+check_show 'format-local:%s' '123456789 -1234' 123456789
+
 # arbitrary time absurdly far in the future
 FUTURE="5758122296 -0400"
 check_show iso       "$FUTURE" "2152-06-19 18:24:56 -0400" TIME_IS_64BIT,TIME_T_IS_64BIT
diff --git a/t/t0007-git-var.sh b/t/t0007-git-var.sh
index 53af92d..e56f4b9 100755
--- a/t/t0007-git-var.sh
+++ b/t/t0007-git-var.sh
@@ -27,6 +27,26 @@
 	)
 '
 
+test_expect_success 'get GIT_DEFAULT_BRANCH without configuration' '
+	(
+		sane_unset GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME &&
+		git init defbranch &&
+		git -C defbranch symbolic-ref --short HEAD >expect &&
+		git var GIT_DEFAULT_BRANCH >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_DEFAULT_BRANCH with configuration' '
+	test_config init.defaultbranch foo &&
+	(
+		sane_unset GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME &&
+		echo foo >expect &&
+		git var GIT_DEFAULT_BRANCH >actual &&
+		test_cmp expect actual
+	)
+'
+
 # For git var -l, we check only a representative variable;
 # testing the whole output would make our test too brittle with
 # respect to unrelated changes in the test suite's environment.
diff --git a/t/t0008-ignores.sh b/t/t0008-ignores.sh
index 42d2314..5575dad 100755
--- a/t/t0008-ignores.sh
+++ b/t/t0008-ignores.sh
@@ -200,7 +200,7 @@
 	do
 		: >$dir/not-ignored &&
 		: >$dir/ignored-and-untracked &&
-		: >$dir/ignored-but-in-index
+		: >$dir/ignored-but-in-index || return 1
 	done &&
 	git add -f ignored-but-in-index a/ignored-but-in-index &&
 	cat <<-\EOF >a/.gitignore &&
diff --git a/t/t0011-hashmap.sh b/t/t0011-hashmap.sh
index e094975..1cb6aa6 100755
--- a/t/t0011-hashmap.sh
+++ b/t/t0011-hashmap.sh
@@ -220,7 +220,7 @@
 	for n in $(test_seq 51)
 	do
 		echo put key$n value$n >> in &&
-		echo NULL >> expect
+		echo NULL >> expect || return 1
 	done &&
 	echo size >> in &&
 	echo 64 51 >> expect &&
@@ -231,7 +231,7 @@
 	for n in $(test_seq 12)
 	do
 		echo remove key$n >> in &&
-		echo value$n >> expect
+		echo value$n >> expect || return 1
 	done &&
 	echo size >> in &&
 	echo 256 40 >> expect &&
diff --git a/t/t0020-crlf.sh b/t/t0020-crlf.sh
index f25ae8b..35cc8c3 100755
--- a/t/t0020-crlf.sh
+++ b/t/t0020-crlf.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 has_cr() {
@@ -22,10 +23,10 @@
 
 	git config core.autocrlf false &&
 
-	for w in Hello world how are you; do echo $w; done >one &&
+	test_write_lines Hello world how are you >one &&
 	mkdir dir &&
-	for w in I am very very fine thank you; do echo $w; done >dir/two &&
-	for w in Oh here is NULQin text here; do echo $w; done | q_to_nul >three &&
+	test_write_lines I am very very fine thank you >dir/two &&
+	test_write_lines Oh here is NULQin text here | q_to_nul >three &&
 	git add . &&
 
 	git commit -m initial &&
@@ -35,7 +36,7 @@
 	two=$(git rev-parse HEAD:dir/two) &&
 	three=$(git rev-parse HEAD:three) &&
 
-	for w in Some extra lines here; do echo $w; done >>one &&
+	test_write_lines Some extra lines here >>one &&
 	git diff >patch.file &&
 	patched=$(git hash-object --stdin <one) &&
 	git read-tree --reset -u HEAD
@@ -46,7 +47,7 @@
 	git config core.autocrlf input &&
 	git config core.safecrlf true &&
 
-	for w in I am all CRLF; do echo $w; done | append_cr >allcrlf &&
+	test_write_lines I am all CRLF | append_cr >allcrlf &&
 	test_must_fail git add allcrlf
 '
 
@@ -55,7 +56,7 @@
 	git config core.autocrlf input &&
 	git config core.safecrlf true &&
 
-	for w in Oh here is CRLFQ in text; do echo $w; done | q_to_cr >mixed &&
+	test_write_lines Oh here is CRLFQ in text | q_to_cr >mixed &&
 	test_must_fail git add mixed
 '
 
@@ -64,7 +65,7 @@
 	git config core.autocrlf true &&
 	git config core.safecrlf true &&
 
-	for w in I am all LF; do echo $w; done >alllf &&
+	test_write_lines I am all LF >alllf &&
 	test_must_fail git add alllf
 '
 
@@ -73,7 +74,7 @@
 	git config core.autocrlf true &&
 	git config core.safecrlf true &&
 
-	for w in Oh here is CRLFQ in text; do echo $w; done | q_to_cr >mixed &&
+	test_write_lines Oh here is CRLFQ in text | q_to_cr >mixed &&
 	test_must_fail git add mixed
 '
 
@@ -82,10 +83,10 @@
 	git config core.autocrlf input &&
 	git config core.safecrlf warn &&
 
-	for w in I am all LF; do echo $w; done >doublewarn &&
+	test_write_lines I am all LF >doublewarn &&
 	git add doublewarn &&
 	git commit -m "nowarn" &&
-	for w in Oh here is CRLFQ in text; do echo $w; done | q_to_cr >doublewarn &&
+	test_write_lines Oh here is CRLFQ in text | q_to_cr >doublewarn &&
 	git add doublewarn 2>err &&
 	grep "CRLF will be replaced by LF" err >err.warnings &&
 	test_line_count = 1 err.warnings
@@ -103,7 +104,7 @@
 	git config core.autocrlf input &&
 	git config core.safecrlf false &&
 
-	for w in I am all CRLF; do echo $w; done | append_cr >allcrlf &&
+	test_write_lines I am all CRLF | append_cr >allcrlf &&
 	git add allcrlf 2>err &&
 	test_must_be_empty err
 '
@@ -351,9 +352,9 @@
 	git config core.autocrlf false &&
 	git config core.safecrlf false &&
 	rm -rf .????* * &&
-	for w in I am all LF; do echo $w; done >alllf &&
-	for w in Oh here is CRLFQ in text; do echo $w; done | q_to_cr >mixed &&
-	for w in I am all CRLF; do echo $w; done | append_cr >allcrlf &&
+	test_write_lines I am all LF >alllf &&
+	test_write_lines Oh here is CRLFQ in text | q_to_cr >mixed &&
+	test_write_lines I am all CRLF | append_cr >allcrlf &&
 	git add -A . &&
 	git commit -m "alllf, allcrlf and mixed only" &&
 	git tag -a -m "message" autocrlf-checkpoint
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index 33dfc9c..bad37ab 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -76,13 +76,13 @@
 	git config filter.rot13.clean ./rot13.sh &&
 
 	{
-	    echo "*.t filter=rot13"
+	    echo "*.t filter=rot13" &&
 	    echo "*.i ident"
 	} >.gitattributes &&
 
 	{
-	    echo a b c d e f g h i j k l m
-	    echo n o p q r s t u v w x y z
+	    echo a b c d e f g h i j k l m &&
+	    echo n o p q r s t u v w x y z &&
 	    echo '\''$Id$'\''
 	} >test &&
 	cat test >test.t &&
@@ -118,17 +118,17 @@
 # If an expanded ident ever gets into the repository, we want to make sure that
 # it is collapsed before being expanded again on checkout
 test_expect_success expanded_in_repo '
-	{
-		echo "File with expanded keywords"
-		echo "\$Id\$"
-		echo "\$Id:\$"
-		echo "\$Id: 0000000000000000000000000000000000000000 \$"
-		echo "\$Id: NoSpaceAtEnd\$"
-		echo "\$Id:NoSpaceAtFront \$"
-		echo "\$Id:NoSpaceAtEitherEnd\$"
-		echo "\$Id: NoTerminatingSymbol"
-		echo "\$Id: Foreign Commit With Spaces \$"
-	} >expanded-keywords.0 &&
+	cat >expanded-keywords.0 <<-\EOF &&
+	File with expanded keywords
+	$Id$
+	$Id:$
+	$Id: 0000000000000000000000000000000000000000 $
+	$Id: NoSpaceAtEnd$
+	$Id:NoSpaceAtFront $
+	$Id:NoSpaceAtEitherEnd$
+	$Id: NoTerminatingSymbol
+	$Id: Foreign Commit With Spaces $
+	EOF
 
 	{
 		cat expanded-keywords.0 &&
@@ -139,17 +139,17 @@
 	git commit -m "File with keywords expanded" &&
 	id=$(git rev-parse --verify :expanded-keywords) &&
 
-	{
-		echo "File with expanded keywords"
-		echo "\$Id: $id \$"
-		echo "\$Id: $id \$"
-		echo "\$Id: $id \$"
-		echo "\$Id: $id \$"
-		echo "\$Id: $id \$"
-		echo "\$Id: $id \$"
-		echo "\$Id: NoTerminatingSymbol"
-		echo "\$Id: Foreign Commit With Spaces \$"
-	} >expected-output.0 &&
+	cat >expected-output.0 <<-EOF &&
+	File with expanded keywords
+	\$Id: $id \$
+	\$Id: $id \$
+	\$Id: $id \$
+	\$Id: $id \$
+	\$Id: $id \$
+	\$Id: $id \$
+	\$Id: NoTerminatingSymbol
+	\$Id: Foreign Commit With Spaces \$
+	EOF
 	{
 		cat expected-output.0 &&
 		printf "\$Id: NoTerminatingSymbolAtEOF"
@@ -159,7 +159,7 @@
 		printf "\$Id: NoTerminatingSymbolAtEOF"
 	} >expected-output-crlf &&
 	{
-		echo "expanded-keywords ident"
+		echo "expanded-keywords ident" &&
 		echo "expanded-keywords-crlf ident text eol=crlf"
 	} >>.gitattributes &&
 
@@ -285,7 +285,7 @@
 test_expect_success 'filtering large input to small output should use little memory' '
 	test_config filter.devnull.clean "cat >/dev/null" &&
 	test_config filter.devnull.required true &&
-	for i in $(test_seq 1 30); do printf "%1048576d" 1; done >30MB &&
+	for i in $(test_seq 1 30); do printf "%1048576d" 1 || return 1; done >30MB &&
 	echo "30MB filter=devnull" >.gitattributes &&
 	GIT_MMAP_LIMIT=1m GIT_ALLOC_LIMIT=1m git add 30MB
 '
@@ -303,7 +303,7 @@
 test_expect_success EXPENSIVE 'filter large file' '
 	test_config filter.largefile.smudge cat &&
 	test_config filter.largefile.clean cat &&
-	for i in $(test_seq 1 2048); do printf "%1048576d" 1; done >2GB &&
+	for i in $(test_seq 1 2048); do printf "%1048576d" 1 || return 1; done >2GB &&
 	echo "2GB filter=largefile" >.gitattributes &&
 	git add 2GB 2>err &&
 	test_must_be_empty err &&
@@ -643,7 +643,7 @@
 		for FILE in "$TEST_ROOT"/*.file
 		do
 			cp "$FILE" . &&
-			rot13.sh <"$FILE" >"$FILE.rot13"
+			rot13.sh <"$FILE" >"$FILE.rot13" || return 1
 		done &&
 
 		echo "*.file filter=protocol" >.gitattributes &&
@@ -682,7 +682,7 @@
 
 		for FILE in *.file
 		do
-			test_cmp_committed_rot13 "$TEST_ROOT/$FILE" $FILE
+			test_cmp_committed_rot13 "$TEST_ROOT/$FILE" $FILE || return 1
 		done
 	)
 '
diff --git a/t/t0026-eol-config.sh b/t/t0026-eol-config.sh
index cdcafcd..f426a18 100755
--- a/t/t0026-eol-config.sh
+++ b/t/t0026-eol-config.sh
@@ -15,8 +15,8 @@
 
 	echo "one text" > .gitattributes &&
 
-	for w in Hello world how are you; do echo $w; done >one &&
-	for w in I am very very fine thank you; do echo $w; done >two &&
+	test_write_lines Hello world how are you >one &&
+	test_write_lines I am very very fine thank you >two &&
 	git add . &&
 
 	git commit -m initial &&
diff --git a/t/t0032-reftable-unittest.sh b/t/t0032-reftable-unittest.sh
new file mode 100755
index 0000000..0ed1497
--- /dev/null
+++ b/t/t0032-reftable-unittest.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+#
+# Copyright (c) 2020 Google LLC
+#
+
+test_description='reftable unittests'
+
+. ./test-lib.sh
+
+test_expect_success 'unittests' '
+	TMPDIR=$(pwd) && export TMPDIR &&
+	test-tool reftable
+'
+
+test_done
diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index 34d1061..71a5d37 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -216,7 +216,7 @@
 	mkdir second &&
 	ln -s ../first second/other &&
 	mkdir third &&
-	dir="$(cd .git; pwd -P)" &&
+	dir="$(cd .git && pwd -P)" &&
 	dir2=third/../second/other/.git &&
 	test "$dir" = "$(test-tool path-utils real_path $dir2)" &&
 	file="$dir"/index &&
@@ -224,7 +224,7 @@
 	basename=blub &&
 	test "$dir/$basename" = "$(cd .git && test-tool path-utils real_path "$basename")" &&
 	ln -s ../first/file .git/syml &&
-	sym="$(cd first; pwd -P)"/file &&
+	sym="$(cd first && pwd -P)"/file &&
 	test "$sym" = "$(test-tool path-utils real_path "$dir2/syml")"
 '
 
diff --git a/t/t0069-oidtree.sh b/t/t0069-oidtree.sh
index 74cc59b..889db50 100755
--- a/t/t0069-oidtree.sh
+++ b/t/t0069-oidtree.sh
@@ -28,7 +28,7 @@
 	EOF
 	{
 		echoid insert 444 1 2 3 4 5 a b c d e &&
-		echoid contains 44 441 440 444 4440 4444
+		echoid contains 44 441 440 444 4440 4444 &&
 		echo clear
 	} | test-tool oidtree >actual &&
 	test_cmp expect actual
@@ -37,11 +37,11 @@
 test_expect_success 'oidtree each' '
 	echoid "" 123 321 321 >expect &&
 	{
-		echoid insert f 9 8 123 321 a b c d e
-		echo each 12300
-		echo each 3211
-		echo each 3210
-		echo each 32100
+		echoid insert f 9 8 123 321 a b c d e &&
+		echo each 12300 &&
+		echo each 3211 &&
+		echo each 3210 &&
+		echo each 32100 &&
 		echo clear
 	} | test-tool oidtree >actual &&
 	test_cmp expect actual
diff --git a/t/t0071-sort.sh b/t/t0071-sort.sh
index a8ab174..6f9a501 100755
--- a/t/t0071-sort.sh
+++ b/t/t0071-sort.sh
@@ -2,6 +2,7 @@
 
 test_description='verify sort functions'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'llist_mergesort()' '
diff --git a/t/t0095-bloom.sh b/t/t0095-bloom.sh
index 7e4ab17..5945973 100755
--- a/t/t0095-bloom.sh
+++ b/t/t0095-bloom.sh
@@ -84,7 +84,7 @@
 	mkdir smallDir &&
 	for i in $(test_seq 0 9)
 	do
-		echo $i >smallDir/$i
+		echo $i >smallDir/$i || return 1
 	done &&
 	git add smallDir &&
 	git commit -m "commit with 10 changes" &&
@@ -102,7 +102,7 @@
 	mkdir bigDir &&
 	for i in $(test_seq 0 511)
 	do
-		echo $i >bigDir/$i
+		echo $i >bigDir/$i || return 1
 	done &&
 	git add bigDir &&
 	git commit -m "commit with 513 changes" &&
diff --git a/t/t0110-urlmatch-normalization.sh b/t/t0110-urlmatch-normalization.sh
index f99529d..4dc9fec 100755
--- a/t/t0110-urlmatch-normalization.sh
+++ b/t/t0110-urlmatch-normalization.sh
@@ -47,7 +47,7 @@
 	test-tool urlmatch-normalization "scheme://@host" &&
 	test-tool urlmatch-normalization "scheme://%00@host" &&
 	! test-tool urlmatch-normalization "scheme://%%@host" &&
-	! test-tool urlmatch-normalization "scheme://host_" &&
+	test-tool urlmatch-normalization "scheme://host_" &&
 	test-tool urlmatch-normalization "scheme://user:pass@host/" &&
 	test-tool urlmatch-normalization "scheme://@host/" &&
 	test-tool urlmatch-normalization "scheme://host/" &&
diff --git a/t/t0200-gettext-basic.sh b/t/t0200-gettext-basic.sh
index 8853d8a..522fb2a 100755
--- a/t/t0200-gettext-basic.sh
+++ b/t/t0200-gettext-basic.sh
@@ -5,6 +5,7 @@
 
 test_description='Gettext support for Git'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./lib-gettext.sh
 
 test_expect_success "sanity: \$GIT_INTERNAL_GETTEXT_SH_SCHEME is set (to $GIT_INTERNAL_GETTEXT_SH_SCHEME)" '
diff --git a/t/t0201-gettext-fallbacks.sh b/t/t0201-gettext-fallbacks.sh
index 6c74df0..8724ce1 100755
--- a/t/t0201-gettext-fallbacks.sh
+++ b/t/t0201-gettext-fallbacks.sh
@@ -8,6 +8,7 @@
 GIT_INTERNAL_GETTEXT_TEST_FALLBACKS=YesPlease
 export GIT_INTERNAL_GETTEXT_TEST_FALLBACKS
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./lib-gettext.sh
 
 test_expect_success "sanity: \$GIT_INTERNAL_GETTEXT_SH_SCHEME is set (to $GIT_INTERNAL_GETTEXT_SH_SCHEME)" '
diff --git a/t/t0202-gettext-perl.sh b/t/t0202-gettext-perl.sh
index a29d166..df2ea34 100755
--- a/t/t0202-gettext-perl.sh
+++ b/t/t0202-gettext-perl.sh
@@ -5,6 +5,7 @@
 
 test_description='Perl gettext interface (Git::I18N)'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./lib-gettext.sh
 
 if ! test_have_prereq PERL; then
diff --git a/t/t0204-gettext-reencode-sanity.sh b/t/t0204-gettext-reencode-sanity.sh
index 8437e51..4f2e0dc 100755
--- a/t/t0204-gettext-reencode-sanity.sh
+++ b/t/t0204-gettext-reencode-sanity.sh
@@ -5,6 +5,7 @@
 
 test_description="Gettext reencoding of our *.po/*.mo files works"
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./lib-gettext.sh
 
 # The constants used in a tricky observation for undefined behaviour
diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index c76485b..f17abd2 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -469,7 +469,7 @@
 		git -C repo rev-list --ignore-missing --objects \
 			--exclude-promisor-objects "$OBJ" &&
 		git -C repo rev-list --ignore-missing --objects-edge-aggressive \
-			--exclude-promisor-objects "$OBJ"
+			--exclude-promisor-objects "$OBJ" || return 1
 	done
 '
 
diff --git a/t/t1002-read-tree-m-u-2way.sh b/t/t1002-read-tree-m-u-2way.sh
index 9c05f5e..ca5c551 100755
--- a/t/t1002-read-tree-m-u-2way.sh
+++ b/t/t1002-read-tree-m-u-2way.sh
@@ -8,6 +8,8 @@
 This is identical to t1001, but uses -u to update the work tree as well.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-read-tree.sh
 
diff --git a/t/t1005-read-tree-reset.sh b/t/t1005-read-tree-reset.sh
index 83b09e1..12e30d7 100755
--- a/t/t1005-read-tree-reset.sh
+++ b/t/t1005-read-tree-reset.sh
@@ -2,6 +2,7 @@
 
 test_description='read-tree -u --reset'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-read-tree.sh
 
diff --git a/t/t1006-cat-file.sh b/t/t1006-cat-file.sh
index 6586283..39382fa 100755
--- a/t/t1006-cat-file.sh
+++ b/t/t1006-cat-file.sh
@@ -211,14 +211,14 @@
 test_expect_success "--batch-check for a non-existent named object" '
     test "foobar42 missing
 foobar84 missing" = \
-    "$( ( echo foobar42; echo_without_newline foobar84; ) | git cat-file --batch-check)"
+    "$( ( echo foobar42 && echo_without_newline foobar84 ) | git cat-file --batch-check)"
 '
 
 test_expect_success "--batch-check for a non-existent hash" '
     test "0000000000000000000000000000000000000042 missing
 0000000000000000000000000000000000000084 missing" = \
-    "$( ( echo 0000000000000000000000000000000000000042;
-	 echo_without_newline 0000000000000000000000000000000000000084; ) |
+    "$( ( echo 0000000000000000000000000000000000000042 &&
+	 echo_without_newline 0000000000000000000000000000000000000084 ) |
        git cat-file --batch-check)"
 '
 
@@ -226,8 +226,8 @@
     test "$tag_sha1 tag $tag_size
 $tag_content
 0000000000000000000000000000000000000000 missing" = \
-    "$( ( echo $tag_sha1;
-	 echo_without_newline 0000000000000000000000000000000000000000; ) |
+    "$( ( echo $tag_sha1 &&
+	 echo_without_newline 0000000000000000000000000000000000000000 ) |
        git cat-file --batch)"
 '
 
@@ -283,7 +283,7 @@
 
 test_expect_success 'setup blobs which are likely to delta' '
 	test-tool genrandom foo 10240 >foo &&
-	{ cat foo; echo plus; } >foo-plus &&
+	{ cat foo && echo plus; } >foo-plus &&
 	git add foo foo-plus &&
 	git commit -m foo &&
 	cat >blobs <<-\EOF
@@ -452,9 +452,8 @@
 	# Create it manually, as "git replace" will die on bogus
 	# types.
 	head=$(git rev-parse --verify HEAD) &&
-	test_when_finished "rm -rf .git/refs/replace" &&
-	mkdir -p .git/refs/replace &&
-	echo $head >.git/refs/replace/$bogus_short_sha1 &&
+	test_when_finished "test-tool ref-store main delete-refs 0 msg refs/replace/$bogus_short_sha1" &&
+	test-tool ref-store main update-ref msg "refs/replace/$bogus_short_sha1" $head $ZERO_OID REF_SKIP_OID_VERIFICATION &&
 
 	cat >expect <<-EOF &&
 	commit
diff --git a/t/t1008-read-tree-overlay.sh b/t/t1008-read-tree-overlay.sh
index 4512fb0b..ad5936e 100755
--- a/t/t1008-read-tree-overlay.sh
+++ b/t/t1008-read-tree-overlay.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-read-tree.sh
 
diff --git a/t/t1010-mktree.sh b/t/t1010-mktree.sh
index 48bfad0..3c08194 100755
--- a/t/t1010-mktree.sh
+++ b/t/t1010-mktree.sh
@@ -6,10 +6,10 @@
 . ./test-lib.sh
 
 test_expect_success setup '
-	for d in a a. a0
+	for d in a a- a0
 	do
 		mkdir "$d" && echo "$d/one" >"$d/one" &&
-		git add "$d"
+		git add "$d" || return 1
 	done &&
 	echo zero >one &&
 	git update-index --add --info-only one &&
diff --git a/t/t1020-subdirectory.sh b/t/t1020-subdirectory.sh
index c2df75e..9fdbb2a 100755
--- a/t/t1020-subdirectory.sh
+++ b/t/t1020-subdirectory.sh
@@ -11,9 +11,9 @@
 
 test_expect_success setup '
 	long="a b c d e f g h i j k l m n o p q r s t u v w x y z" &&
-	for c in $long; do echo $c; done >one &&
+	test_write_lines $long >one &&
 	mkdir dir &&
-	for c in x y z $long a b c; do echo $c; done >dir/two &&
+	test_write_lines x y z $long a b c >dir/two &&
 	cp one original.one &&
 	cp dir/two original.two
 '
@@ -22,7 +22,7 @@
 	git update-index --add one &&
 	case "$(git ls-files)" in
 	one) echo pass one ;;
-	*) echo bad one; exit 1 ;;
+	*) echo bad one; return 1 ;;
 	esac &&
 	(
 		cd dir &&
@@ -34,7 +34,7 @@
 	) &&
 	case "$(git ls-files)" in
 	dir/two"$LF"one) echo pass both ;;
-	*) echo bad; exit 1 ;;
+	*) echo bad; return 1 ;;
 	esac
 '
 
@@ -57,7 +57,7 @@
 	echo d >>dir/two &&
 	case "$(git diff-files --name-only)" in
 	dir/two"$LF"one) echo pass top ;;
-	*) echo bad top; exit 1 ;;
+	*) echo bad top; return 1 ;;
 	esac &&
 	# diff should not omit leading paths
 	(
diff --git a/t/t1022-read-tree-partial-clone.sh b/t/t1022-read-tree-partial-clone.sh
index a763e27..a9953b6 100755
--- a/t/t1022-read-tree-partial-clone.sh
+++ b/t/t1022-read-tree-partial-clone.sh
@@ -4,9 +4,6 @@
 
 TEST_NO_CREATE_REPO=1
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 
 test_expect_success 'read-tree in partial clone prefetches in one batch' '
diff --git a/t/t1050-large.sh b/t/t1050-large.sh
index 6bc1d76..4f3aa17 100755
--- a/t/t1050-large.sh
+++ b/t/t1050-large.sh
@@ -51,42 +51,32 @@
 test_expect_success 'add a large file or two' '
 	git add large1 huge large2 &&
 	# make sure we got a single packfile and no loose objects
-	bad= count=0 idx= &&
+	count=0 idx= &&
 	for p in .git/objects/pack/pack-*.pack
 	do
-		count=$(( $count + 1 ))
-		if test_path_is_file "$p" &&
-		   idx=${p%.pack}.idx && test_path_is_file "$idx"
-		then
-			continue
-		fi
-		bad=t
+		count=$(( $count + 1 )) &&
+		test_path_is_file "$p" &&
+		idx=${p%.pack}.idx &&
+		test_path_is_file "$idx" || return 1
 	done &&
-	test -z "$bad" &&
 	test $count = 1 &&
 	cnt=$(git show-index <"$idx" | wc -l) &&
 	test $cnt = 2 &&
 	for l in .git/objects/$OIDPATH_REGEX
 	do
-		test_path_is_file "$l" || continue
-		bad=t
+		test_path_is_missing "$l" || return 1
 	done &&
-	test -z "$bad" &&
 
 	# attempt to add another copy of the same
 	git add large3 &&
 	bad= count=0 &&
 	for p in .git/objects/pack/pack-*.pack
 	do
-		count=$(( $count + 1 ))
-		if test_path_is_file "$p" &&
-		   idx=${p%.pack}.idx && test_path_is_file "$idx"
-		then
-			continue
-		fi
-		bad=t
+		count=$(( $count + 1 )) &&
+		test_path_is_file "$p" &&
+		idx=${p%.pack}.idx &&
+		test_path_is_file "$idx" || return 1
 	done &&
-	test -z "$bad" &&
 	test $count = 1
 '
 
@@ -115,7 +105,7 @@
 		count=0 &&
 		for pi in .git/objects/pack/pack-*.idx
 		do
-			test_path_is_file "$pi" && count=$(( $count + 1 ))
+			test_path_is_file "$pi" && count=$(( $count + 1 )) || return 1
 		done &&
 		test $count = 2 &&
 
@@ -128,7 +118,7 @@
 
 		for pi in .git/objects/pack/pack-*.idx
 		do
-			git show-index <"$pi"
+			git show-index <"$pi" || return 1
 		done |
 		sed -e "s/^[0-9]* \([0-9a-f]*\) .*/\1/" |
 		sort >actual &&
diff --git a/t/t1051-large-conversion.sh b/t/t1051-large-conversion.sh
index 8b7640b..042b0e4 100755
--- a/t/t1051-large-conversion.sh
+++ b/t/t1051-large-conversion.sh
@@ -83,4 +83,30 @@
 	test_cmp small.clean large.clean
 '
 
+# This smudge filter prepends 5GB of zeros to the file it checks out. This
+# ensures that smudging doesn't mangle large files on 64-bit Windows.
+test_expect_success EXPENSIVE,SIZE_T_IS_64BIT,!LONG_IS_64BIT \
+		'files over 4GB convert on output' '
+	test_commit test small "a small file" &&
+	small_size=$(test_file_size small) &&
+	test_config filter.makelarge.smudge \
+		"test-tool genzeros $((5*1024*1024*1024)) && cat" &&
+	echo "small filter=makelarge" >.gitattributes &&
+	rm small &&
+	git checkout -- small &&
+	size=$(test_file_size small) &&
+	test "$size" -eq $((5 * 1024 * 1024 * 1024 + $small_size))
+'
+
+# This clean filter writes down the size of input it receives. By checking against
+# the actual size, we ensure that cleaning doesn't mangle large files on 64-bit Windows.
+test_expect_success EXPENSIVE,SIZE_T_IS_64BIT,!LONG_IS_64BIT \
+		'files over 4GB convert on input' '
+	test-tool genzeros $((5*1024*1024*1024)) >big &&
+	test_config filter.checklarge.clean "wc -c >big.size" &&
+	echo "big filter=checklarge" >.gitattributes &&
+	git add big &&
+	test $(test_file_size big) -eq $(cat big.size)
+'
+
 test_done
diff --git a/t/t1091-sparse-checkout-builtin.sh b/t/t1091-sparse-checkout-builtin.sh
index 272ba1b..4277698 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -41,7 +41,15 @@
 	)
 '
 
-test_expect_success 'git sparse-checkout list (empty)' '
+test_expect_success 'git sparse-checkout list (not sparse)' '
+	test_must_fail git -C repo sparse-checkout list >list 2>err &&
+	test_must_be_empty list &&
+	test_i18ngrep "this worktree is not sparse" err
+'
+
+test_expect_success 'git sparse-checkout list (not sparse)' '
+	git -C repo sparse-checkout set &&
+	rm repo/.git/info/sparse-checkout &&
 	git -C repo sparse-checkout list >list 2>err &&
 	test_must_be_empty list &&
 	test_i18ngrep "this worktree is not sparse (sparse-checkout file may not exist)" err
@@ -103,6 +111,18 @@
 	check_files clone a
 '
 
+test_expect_success 'switching to cone mode with non-cone mode patterns' '
+	git init bad-patterns &&
+	(
+		cd bad-patterns &&
+		git sparse-checkout init &&
+		git sparse-checkout add dir &&
+		git config core.sparseCheckoutCone true &&
+		test_must_fail git sparse-checkout add dir 2>err &&
+		grep "existing sparse-checkout patterns do not use cone mode" err
+	)
+'
+
 test_expect_success 'interaction with clone --no-checkout (unborn index)' '
 	git clone --no-checkout "file://$(pwd)/repo" clone_no_checkout &&
 	git -C clone_no_checkout sparse-checkout init --cone &&
@@ -165,12 +185,14 @@
 '
 
 test_expect_success 'add to sparse-checkout' '
-	cat repo/.git/info/sparse-checkout >expect &&
+	cat repo/.git/info/sparse-checkout >old &&
+	test_when_finished cp old repo/.git/info/sparse-checkout &&
 	cat >add <<-\EOF &&
 	pattern1
 	/folder1/
 	pattern2
 	EOF
+	cat old >expect &&
 	cat add >>expect &&
 	git -C repo sparse-checkout add --stdin <add &&
 	git -C repo sparse-checkout list >actual &&
@@ -212,12 +234,27 @@
 
 		git -C repo sparse-checkout init --cone --sparse-index &&
 		test_cmp_config -C repo true index.sparse &&
-		test-tool -C repo read-cache --table >cache &&
-		grep " tree " cache &&
-
+		git -C repo ls-files --sparse >sparse &&
 		git -C repo sparse-checkout disable &&
-		test-tool -C repo read-cache --table >cache &&
-		! grep " tree " cache &&
+		git -C repo ls-files --sparse >full &&
+
+		cat >expect <<-\EOF &&
+		@@ -1,4 +1,7 @@
+		 a
+		-deep/
+		-folder1/
+		-folder2/
+		+deep/a
+		+deep/deeper1/a
+		+deep/deeper1/deepest/a
+		+deep/deeper2/a
+		+folder1/a
+		+folder2/a
+		EOF
+
+		diff -u sparse full | tail -n +3 >actual &&
+		test_cmp expect actual &&
+
 		git -C repo config --list >config &&
 		! grep index.sparse config
 	)
@@ -586,7 +623,7 @@
 		!/*/
 		something$c-else/
 		EOF
-		check_read_tree_errors repo "a" "disabling cone pattern matching"
+		check_read_tree_errors repo "a" "disabling cone pattern matching" || return 1
 	done
 '
 
@@ -708,4 +745,25 @@
 	test_cmp expect out
 '
 
+test_expect_success 'malformed cone-mode patterns' '
+	git -C repo sparse-checkout init --cone &&
+	mkdir -p repo/foo/bar &&
+	touch repo/foo/bar/x repo/foo/y &&
+	cat >repo/.git/info/sparse-checkout <<-\EOF &&
+	/*
+	!/*/
+	/foo/
+	!/foo/*/
+	/foo/\*/
+	EOF
+
+	# Listing the patterns will notice the duplicate pattern and
+	# emit a warning. It will list the patterns directly instead
+	# of using the cone-mode translation to a set of directories.
+	git -C repo sparse-checkout list >actual 2>err &&
+	test_cmp repo/.git/info/sparse-checkout actual &&
+	grep "warning: your sparse-checkout file may have issues: pattern .* is repeated" err &&
+	grep "warning: disabling cone pattern matching" err
+'
+
 test_done
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index 16fbd2c..4ba1617 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -19,6 +19,8 @@
 		mkdir folder1 folder2 deep x &&
 		mkdir deep/deeper1 deep/deeper2 deep/before deep/later &&
 		mkdir deep/deeper1/deepest &&
+		mkdir deep/deeper1/deepest2 &&
+		mkdir deep/deeper1/deepest3 &&
 		echo "after deeper1" >deep/e &&
 		echo "after deepest" >deep/deeper1/e &&
 		cp a folder1 &&
@@ -30,7 +32,9 @@
 		cp a deep/deeper2 &&
 		cp a deep/later &&
 		cp a deep/deeper1/deepest &&
-		cp -r deep/deeper1/deepest deep/deeper2 &&
+		cp a deep/deeper1/deepest2 &&
+		cp a deep/deeper1/deepest3 &&
+		cp -r deep/deeper1/ deep/deeper2 &&
 		mkdir deep/deeper1/0 &&
 		mkdir deep/deeper1/0/0 &&
 		touch deep/deeper1/0/1 &&
@@ -126,6 +130,8 @@
 
 		git checkout -b deepest base &&
 		echo "updated deepest" >deep/deeper1/deepest/a &&
+		echo "updated deepest2" >deep/deeper1/deepest2/a &&
+		echo "updated deepest3" >deep/deeper1/deepest3/a &&
 		git commit -a -m "update deepest" &&
 
 		git checkout -f base &&
@@ -200,45 +206,42 @@
 test_expect_success 'sparse-index contents' '
 	init_repos &&
 
-	test-tool -C sparse-index read-cache --table >cache &&
+	git -C sparse-index ls-files --sparse --stage >cache &&
 	for dir in folder1 folder2 x
 	do
 		TREE=$(git -C sparse-index rev-parse HEAD:$dir) &&
-		grep "040000 tree $TREE	$dir/" cache \
+		grep "040000 $TREE 0	$dir/" cache \
 			|| return 1
 	done &&
 
 	git -C sparse-index sparse-checkout set folder1 &&
 
-	test-tool -C sparse-index read-cache --table >cache &&
+	git -C sparse-index ls-files --sparse --stage >cache &&
 	for dir in deep folder2 x
 	do
 		TREE=$(git -C sparse-index rev-parse HEAD:$dir) &&
-		grep "040000 tree $TREE	$dir/" cache \
+		grep "040000 $TREE 0	$dir/" cache \
 			|| return 1
 	done &&
 
 	git -C sparse-index sparse-checkout set deep/deeper1 &&
 
-	test-tool -C sparse-index read-cache --table >cache &&
+	git -C sparse-index ls-files --sparse --stage >cache &&
 	for dir in deep/deeper2 folder1 folder2 x
 	do
 		TREE=$(git -C sparse-index rev-parse HEAD:$dir) &&
-		grep "040000 tree $TREE	$dir/" cache \
+		grep "040000 $TREE 0	$dir/" cache \
 			|| return 1
 	done &&
 
-	# Disabling the sparse-index removes tree entries with full ones
+	# Disabling the sparse-index replaces tree entries with full ones
 	git -C sparse-index sparse-checkout init --no-sparse-index &&
-
-	test-tool -C sparse-index read-cache --table >cache &&
-	! grep "040000 tree" cache &&
-	test_sparse_match test-tool read-cache --table
+	test_sparse_match git ls-files --stage --sparse
 '
 
 test_expect_success 'expanded in-memory index matches full index' '
 	init_repos &&
-	test_sparse_match test-tool read-cache --expand --table
+	test_sparse_match git ls-files --stage
 '
 
 test_expect_success 'status with options' '
@@ -301,6 +304,14 @@
 	test_all_match git checkout -
 '
 
+test_expect_success 'deep changes during checkout' '
+	init_repos &&
+
+	test_sparse_match git sparse-checkout set deep/deeper1/deepest &&
+	test_all_match git checkout deepest &&
+	test_all_match git checkout base
+'
+
 test_expect_success 'add outside sparse cone' '
 	init_repos &&
 
@@ -401,7 +412,7 @@
 	test_all_match git reset --hard update-folder2
 '
 
-test_expect_success 'diff --staged' '
+test_expect_success 'diff --cached' '
 	init_repos &&
 
 	write_script edit-contents <<-\EOF &&
@@ -410,10 +421,10 @@
 	run_on_all ../edit-contents &&
 
 	test_all_match git diff &&
-	test_all_match git diff --staged &&
+	test_all_match git diff --cached &&
 	test_all_match git add README.md &&
 	test_all_match git diff &&
-	test_all_match git diff --staged
+	test_all_match git diff --cached
 '
 
 # NEEDSWORK: sparse-checkout behaves differently from full-checkout when
@@ -430,8 +441,8 @@
 		test_all_match git checkout rename-base &&
 		test_all_match git checkout $branch -- . &&
 		test_all_match git status --porcelain=v2 &&
-		test_all_match git diff --staged --no-renames &&
-		test_all_match git diff --staged --find-renames || return 1
+		test_all_match git diff --cached --no-renames &&
+		test_all_match git diff --cached --find-renames || return 1
 	done
 '
 
@@ -450,8 +461,8 @@
 		test_all_match git checkout $branch &&
 		test_all_match git checkout rename-base -- . &&
 		test_all_match git status --porcelain=v2 &&
-		test_all_match git diff --staged --no-renames &&
-		test_all_match git diff --staged --find-renames || return 1
+		test_all_match git diff --cached --no-renames &&
+		test_all_match git diff --cached --find-renames || return 1
 	done
 '
 
@@ -472,43 +483,150 @@
 test_expect_success 'blame with pathspec inside sparse definition' '
 	init_repos &&
 
-	test_all_match git blame a &&
-	test_all_match git blame deep/a &&
-	test_all_match git blame deep/deeper1/a &&
-	test_all_match git blame deep/deeper1/deepest/a
+	for file in a \
+			deep/a \
+			deep/deeper1/a \
+			deep/deeper1/deepest/a
+	do
+		test_all_match git blame $file
+	done
 '
 
-# TODO: blame currently does not support blaming files outside of the
-# sparse definition. It complains that the file doesn't exist locally.
-test_expect_failure 'blame with pathspec outside sparse definition' '
+# Without a revision specified, blame will error if passed any file that
+# is not present in the working directory (even if the file is tracked).
+# Here we just verify that this is also true with sparse checkouts.
+test_expect_success 'blame with pathspec outside sparse definition' '
 	init_repos &&
+	test_sparse_match git sparse-checkout set &&
 
-	test_all_match git blame folder1/a &&
-	test_all_match git blame folder2/a &&
-	test_all_match git blame deep/deeper2/a &&
-	test_all_match git blame deep/deeper2/deepest/a
+	for file in a \
+			deep/a \
+			deep/deeper1/a \
+			deep/deeper1/deepest/a
+	do
+		test_sparse_match test_must_fail git blame $file &&
+		cat >expect <<-EOF &&
+		fatal: Cannot lstat '"'"'$file'"'"': No such file or directory
+		EOF
+		# We compare sparse-checkout-err and sparse-index-err in
+		# `test_sparse_match`. Given we know they are the same, we
+		# only check the content of sparse-index-err here.
+		test_cmp expect sparse-index-err
+	done
 '
 
-# NEEDSWORK: a sparse-checkout behaves differently from a full checkout
-# in this scenario, but it shouldn't.
-test_expect_failure 'checkout and reset (mixed)' '
+test_expect_success 'checkout and reset (mixed)' '
 	init_repos &&
 
 	test_all_match git checkout -b reset-test update-deep &&
 	test_all_match git reset deepest &&
-	test_all_match git reset update-folder1 &&
-	test_all_match git reset update-folder2
+
+	# Because skip-worktree is preserved, resetting to update-folder1
+	# will show worktree changes for folder1/a in full-checkout, but not
+	# in sparse-checkout or sparse-index.
+	git -C full-checkout reset update-folder1 >full-checkout-out &&
+	test_sparse_match git reset update-folder1 &&
+	grep "M	folder1/a" full-checkout-out &&
+	! grep "M	folder1/a" sparse-checkout-out &&
+	run_on_sparse test_path_is_missing folder1
 '
 
-# NEEDSWORK: a sparse-checkout behaves differently from a full checkout
-# in this scenario, but it shouldn't.
-test_expect_success 'checkout and reset (mixed) [sparse]' '
+test_expect_success 'checkout and reset (merge)' '
 	init_repos &&
 
-	test_sparse_match git checkout -b reset-test update-deep &&
-	test_sparse_match git reset deepest &&
-	test_sparse_match git reset update-folder1 &&
-	test_sparse_match git reset update-folder2
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+
+	test_all_match git checkout -b reset-test update-deep &&
+	run_on_all ../edit-contents a &&
+	test_all_match git reset --merge deepest &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git reset --hard update-deep &&
+	run_on_all ../edit-contents deep/a &&
+	test_all_match test_must_fail git reset --merge deepest
+'
+
+test_expect_success 'checkout and reset (keep)' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+
+	test_all_match git checkout -b reset-test update-deep &&
+	run_on_all ../edit-contents a &&
+	test_all_match git reset --keep deepest &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git reset --hard update-deep &&
+	run_on_all ../edit-contents deep/a &&
+	test_all_match test_must_fail git reset --keep deepest
+'
+
+test_expect_success 'reset with pathspecs inside sparse definition' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+
+	test_all_match git checkout -b reset-test update-deep &&
+	run_on_all ../edit-contents deep/a &&
+
+	test_all_match git reset base -- deep/a &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git reset base -- nonexistent-file &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git reset deepest -- deep &&
+	test_all_match git status --porcelain=v2
+'
+
+# Although the working tree differs between full and sparse checkouts after
+# reset, the state of the index is the same.
+test_expect_success 'reset with pathspecs outside sparse definition' '
+	init_repos &&
+	test_all_match git checkout -b reset-test base &&
+
+	test_sparse_match git reset update-folder1 -- folder1 &&
+	git -C full-checkout reset update-folder1 -- folder1 &&
+	test_sparse_match git status --porcelain=v2 &&
+	test_all_match git rev-parse HEAD:folder1 &&
+
+	test_sparse_match git reset update-folder2 -- folder2/a &&
+	git -C full-checkout reset update-folder2 -- folder2/a &&
+	test_sparse_match git status --porcelain=v2 &&
+	test_all_match git rev-parse HEAD:folder2/a
+'
+
+test_expect_success 'reset with wildcard pathspec' '
+	init_repos &&
+
+	test_all_match git reset update-deep -- deep\* &&
+	test_all_match git ls-files -s -- deep &&
+
+	test_all_match git reset deepest -- deep\*\*\* &&
+	test_all_match git ls-files -s -- deep &&
+
+	# The following `git reset`s result in updating the index on files with
+	# `skip-worktree` enabled. To avoid failing due to discrepencies in reported
+	# "modified" files, `test_sparse_match` reset is performed separately from
+	# "full-checkout" reset, then the index contents of all repos are verified.
+
+	test_sparse_match git reset update-folder1 -- \*/a &&
+	git -C full-checkout reset update-folder1 -- \*/a &&
+	test_all_match git ls-files -s -- deep/a folder1/a &&
+
+	test_sparse_match git reset update-folder2 -- folder\* &&
+	git -C full-checkout reset update-folder2 -- folder\* &&
+	test_all_match git ls-files -s -- folder10 folder1 folder2 &&
+
+	test_sparse_match git reset base -- folder1/\* &&
+	git -C full-checkout reset base -- folder1/\* &&
+	test_all_match git ls-files -s -- folder1
 '
 
 test_expect_success 'merge, cherry-pick, and rebase' '
@@ -680,20 +798,61 @@
 
 	# having a submodule prevents "modules" from collapse
 	test_sparse_match git sparse-checkout set deep/deeper1 &&
-	test-tool -C sparse-index read-cache --table >cache &&
-	grep "100644 blob .*	modules/a" cache &&
-	grep "160000 commit $(git -C initial-repo rev-parse HEAD)	modules/sub" cache
+	git -C sparse-index ls-files --sparse --stage >cache &&
+	grep "100644 .*	modules/a" cache &&
+	grep "160000 $(git -C initial-repo rev-parse HEAD) 0	modules/sub" cache
 '
 
+# When working with a sparse index, some commands will need to expand the
+# index to operate properly. If those commands also write the index back
+# to disk, they need to convert the index to sparse before writing.
+# This test verifies that both of these events are logged in trace2 logs.
 test_expect_success 'sparse-index is expanded and converted back' '
 	init_repos &&
 
-	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
-		git -C sparse-index -c core.fsmonitor="" reset --hard &&
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
+		git -C sparse-index reset -- folder1/a &&
 	test_region index convert_to_sparse trace2.txt &&
+	test_region index ensure_full_index trace2.txt &&
+
+	# ls-files expands on read, but does not write.
+	rm trace2.txt &&
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+		git -C sparse-index ls-files &&
 	test_region index ensure_full_index trace2.txt
 '
 
+test_expect_success 'index.sparse disabled inline uses full index' '
+	init_repos &&
+
+	# When index.sparse is disabled inline with `git status`, the
+	# index is expanded at the beginning of the execution then never
+	# converted back to sparse. It is then written to disk as a full index.
+	rm -f trace2.txt &&
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+		git -C sparse-index -c index.sparse=false status &&
+	! test_region index convert_to_sparse trace2.txt &&
+	test_region index ensure_full_index trace2.txt &&
+
+	# Since index.sparse is set to true at a repo level, the index
+	# is converted from full to sparse when read, then never expanded
+	# over the course of `git status`. It is written to disk as a sparse
+	# index.
+	rm -f trace2.txt &&
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+		git -C sparse-index status &&
+	test_region index convert_to_sparse trace2.txt &&
+	! test_region index ensure_full_index trace2.txt &&
+
+	# Now that the index has been written to disk as sparse, it is not
+	# converted to sparse (or expanded to full) when read by `git status`.
+	rm -f trace2.txt &&
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+		git -C sparse-index status &&
+	! test_region index convert_to_sparse trace2.txt &&
+	! test_region index ensure_full_index trace2.txt
+'
+
 ensure_not_expanded () {
 	rm -f trace2.txt &&
 	echo >>sparse-index/untracked.txt &&
@@ -702,10 +861,10 @@
 	then
 		shift &&
 		test_must_fail env \
-			GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+			GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
 			git -C sparse-index "$@" || return 1
 	else
-		GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+		GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
 			git -C sparse-index "$@" || return 1
 	fi &&
 	test_region ! index ensure_full_index trace2.txt
@@ -715,6 +874,7 @@
 	init_repos &&
 
 	ensure_not_expanded status &&
+	ensure_not_expanded ls-files --sparse &&
 	ensure_not_expanded commit --allow-empty -m empty &&
 	echo >>sparse-index/a &&
 	ensure_not_expanded commit -a -m a &&
@@ -726,9 +886,9 @@
 	ensure_not_expanded checkout - &&
 	ensure_not_expanded switch rename-out-to-out &&
 	ensure_not_expanded switch - &&
-	git -C sparse-index reset --hard &&
+	ensure_not_expanded reset --hard &&
 	ensure_not_expanded checkout rename-out-to-out -- deep/deeper1 &&
-	git -C sparse-index reset --hard &&
+	ensure_not_expanded reset --hard &&
 	ensure_not_expanded restore -s rename-out-to-out -- deep/deeper1 &&
 
 	echo >>sparse-index/README.md &&
@@ -738,6 +898,34 @@
 	echo >>sparse-index/untracked.txt &&
 	ensure_not_expanded add . &&
 
+	for ref in update-deep update-folder1 update-folder2 update-deep
+	do
+		echo >>sparse-index/README.md &&
+		ensure_not_expanded reset --hard $ref || return 1
+	done &&
+
+	ensure_not_expanded reset --mixed base &&
+	ensure_not_expanded reset --hard update-deep &&
+	ensure_not_expanded reset --keep base &&
+	ensure_not_expanded reset --merge update-deep &&
+	ensure_not_expanded reset --hard &&
+
+	ensure_not_expanded reset base -- deep/a &&
+	ensure_not_expanded reset base -- nonexistent-file &&
+	ensure_not_expanded reset deepest -- deep &&
+
+	# Although folder1 is outside the sparse definition, it exists as a
+	# directory entry in the index, so the pathspec will not force the
+	# index to be expanded.
+	ensure_not_expanded reset deepest -- folder1 &&
+	ensure_not_expanded reset deepest -- folder1/ &&
+
+	# Wildcard identifies only in-cone files, no index expansion
+	ensure_not_expanded reset deepest -- deep/\* &&
+
+	# Wildcard identifies only full sparse directories, no index expansion
+	ensure_not_expanded reset deepest -- folder\* &&
+
 	ensure_not_expanded checkout -f update-deep &&
 	test_config -C sparse-index pull.twohead ort &&
 	(
@@ -767,6 +955,158 @@
 	)
 '
 
+test_expect_success 'sparse index is not expanded: diff' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+
+	# Add file within cone
+	test_sparse_match git sparse-checkout set deep &&
+	run_on_all ../edit-contents deep/testfile &&
+	test_all_match git add deep/testfile &&
+	run_on_all ../edit-contents deep/testfile &&
+
+	test_all_match git diff &&
+	test_all_match git diff --cached &&
+	ensure_not_expanded diff &&
+	ensure_not_expanded diff --cached &&
+
+	# Add file outside cone
+	test_all_match git reset --hard &&
+	run_on_all mkdir newdirectory &&
+	run_on_all ../edit-contents newdirectory/testfile &&
+	test_sparse_match git sparse-checkout set newdirectory &&
+	test_all_match git add newdirectory/testfile &&
+	run_on_all ../edit-contents newdirectory/testfile &&
+	test_sparse_match git sparse-checkout set &&
+
+	test_all_match git diff &&
+	test_all_match git diff --cached &&
+	ensure_not_expanded diff &&
+	ensure_not_expanded diff --cached &&
+
+	# Merge conflict outside cone
+	# The sparse checkout will report a warning that is not in the
+	# full checkout, so we use `run_on_all` instead of
+	# `test_all_match`
+	run_on_all git reset --hard &&
+	test_all_match git checkout merge-left &&
+	test_all_match test_must_fail git merge merge-right &&
+
+	test_all_match git diff &&
+	test_all_match git diff --cached &&
+	ensure_not_expanded diff &&
+	ensure_not_expanded diff --cached
+'
+
+test_expect_success 'sparse index is not expanded: blame' '
+	init_repos &&
+
+	for file in a \
+			deep/a \
+			deep/deeper1/a \
+			deep/deeper1/deepest/a
+	do
+		ensure_not_expanded blame $file
+	done
+'
+
+test_expect_success 'sparse index is not expanded: fetch/pull' '
+	init_repos &&
+
+	git -C sparse-index remote add full "file://$(pwd)/full-checkout" &&
+	ensure_not_expanded fetch full &&
+	git -C full-checkout commit --allow-empty -m "for pull merge" &&
+	git -C sparse-index commit --allow-empty -m "for pull merge" &&
+	ensure_not_expanded pull full base
+'
+
+test_expect_success 'ls-files' '
+	init_repos &&
+
+	# Use a smaller sparse-checkout for reduced output
+	test_sparse_match git sparse-checkout set &&
+
+	# Behavior agrees by default. Sparse index is expanded.
+	test_all_match git ls-files &&
+
+	# With --sparse, the sparse index data changes behavior.
+	git -C sparse-index ls-files --sparse >actual &&
+
+	cat >expect <<-\EOF &&
+	a
+	deep/
+	e
+	folder1-
+	folder1.x
+	folder1/
+	folder10
+	folder2/
+	g
+	x/
+	z
+	EOF
+
+	test_cmp expect actual &&
+
+	# With --sparse and no sparse index, nothing changes.
+	git -C sparse-checkout ls-files >dense &&
+	git -C sparse-checkout ls-files --sparse >sparse &&
+	test_cmp dense sparse &&
+
+	# Set up a strange condition of having a file edit
+	# outside of the sparse-checkout cone. This is just
+	# to verify that sparse-checkout and sparse-index
+	# behave the same in this case.
+	write_script edit-content <<-\EOF &&
+	mkdir folder1 &&
+	echo content >>folder1/a
+	EOF
+	run_on_sparse ../edit-content &&
+
+	# ls-files does not currently notice modified files whose
+	# cache entries are marked SKIP_WORKTREE. This may change
+	# in the future, but here we test that sparse index does
+	# not accidentally create a change of behavior.
+	test_sparse_match git ls-files --modified &&
+	test_must_be_empty sparse-checkout-out &&
+	test_must_be_empty sparse-index-out &&
+
+	git -C sparse-index ls-files --sparse --modified >sparse-index-out &&
+	test_must_be_empty sparse-index-out &&
+
+	# Add folder1 to the sparse-checkout cone and
+	# check that ls-files shows the expanded files.
+	test_sparse_match git sparse-checkout add folder1 &&
+	test_sparse_match git ls-files --modified &&
+
+	test_all_match git ls-files &&
+	git -C sparse-index ls-files --sparse >actual &&
+
+	cat >expect <<-\EOF &&
+	a
+	deep/
+	e
+	folder1-
+	folder1.x
+	folder1/0/0/0
+	folder1/0/1
+	folder1/a
+	folder10
+	folder2/
+	g
+	x/
+	z
+	EOF
+
+	test_cmp expect actual &&
+
+	# Double-check index expansion is avoided
+	ensure_not_expanded ls-files --sparse
+'
+
 # NEEDSWORK: a sparse-checkout behaves differently from a full checkout
 # in this scenario, but it shouldn't.
 test_expect_success 'reset mixed and checkout orphan' '
@@ -782,13 +1122,13 @@
 	# the sparse checkouts skip "adding" the other side of
 	# the conflict.
 	test_sparse_match git reset --mixed HEAD~1 &&
-	test_sparse_match test-tool read-cache --table --expand &&
+	test_sparse_match git ls-files --stage &&
 	test_sparse_match git status --porcelain=v2 &&
 
 	# At this point, sparse-checkouts behave differently
 	# from the full-checkout.
 	test_sparse_match git checkout --orphan new-branch &&
-	test_sparse_match test-tool read-cache --table --expand &&
+	test_sparse_match git ls-files --stage &&
 	test_sparse_match git status --porcelain=v2
 '
 
diff --git a/t/t1300-config.sh b/t/t1300-config.sh
index 9ff46f3..78359f1 100755
--- a/t/t1300-config.sh
+++ b/t/t1300-config.sh
@@ -8,6 +8,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'clear default config' '
@@ -717,8 +718,8 @@
 	rm -f result &&
 	for i in 1 2 3 4
 	do
-	    git config --bool --get bool.true$i >>result
-	    git config --bool --get bool.false$i >>result
+	    git config --bool --get bool.true$i >>result &&
+	    git config --bool --get bool.false$i >>result || return 1
 	done &&
 	test_cmp expect result'
 
@@ -901,7 +902,7 @@
 	EOF
 	: "work around heredoc parsing bug fixed in dash 0.5.7 (in ec2c84d)" &&
 	{
-		echo "$rel_out $(git config --expiry-date date.valid1)"
+		echo "$rel_out $(git config --expiry-date date.valid1)" &&
 		git config --expiry-date date.valid2 &&
 		git config --expiry-date date.valid3 &&
 		git config --expiry-date date.valid4 &&
diff --git a/t/t1303-wacky-config.sh b/t/t1303-wacky-config.sh
index 0000e66..0506f3d 100755
--- a/t/t1303-wacky-config.sh
+++ b/t/t1303-wacky-config.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='Test wacky input to git config'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # Leaving off the newline is intentional!
diff --git a/t/t1307-config-blob.sh b/t/t1307-config-blob.sh
index 930dce0..0a7099d 100755
--- a/t/t1307-config-blob.sh
+++ b/t/t1307-config-blob.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='support for reading config from a blob'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'create config blob' '
diff --git a/t/t1308-config-set.sh b/t/t1308-config-set.sh
index 88b119a..b38e158 100755
--- a/t/t1308-config-set.sh
+++ b/t/t1308-config-set.sh
@@ -2,6 +2,7 @@
 
 test_description='Test git config-set API in different settings'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # 'check_config get_* section.key value' verifies that the entry for
diff --git a/t/t1309-early-config.sh b/t/t1309-early-config.sh
index b4a9158..537435b 100755
--- a/t/t1309-early-config.sh
+++ b/t/t1309-early-config.sh
@@ -2,6 +2,7 @@
 
 test_description='Test read_early_config()'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'read early config' '
diff --git a/t/t1310-config-default.sh b/t/t1310-config-default.sh
index 6049d91..09b10c1 100755
--- a/t/t1310-config-default.sh
+++ b/t/t1310-config-default.sh
@@ -2,6 +2,7 @@
 
 test_description='Test git config in different settings (with --default)'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'uses --default when entry missing' '
diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 0d4f73a..cf58cf0 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -4,9 +4,6 @@
 #
 
 test_description='Test git update-ref and basic ref logging'
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 
 Z=$ZERO_OID
@@ -321,8 +318,9 @@
 $B $A $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150860 +0000
 EOF
 test_expect_success "verifying $m's log (logged by touch)" '
-	test_when_finished "rm -rf .git/$m .git/logs expect" &&
-	test_cmp expect .git/logs/$m
+	test_when_finished "git update-ref -d $m && rm -rf .git/logs actual expect" &&
+	test-tool ref-store main for-each-reflog-ent $m >actual &&
+	test_cmp actual expect
 '
 
 test_expect_success "create $m (logged by config)" '
@@ -350,8 +348,9 @@
 $B $A $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150980 +0000
 EOF
 test_expect_success "verifying $m's log (logged by config)" '
-	test_when_finished "rm -f .git/$m .git/logs/$m expect" &&
-	test_cmp expect .git/logs/$m
+	test_when_finished "git update-ref -d $m && rm -rf .git/logs actual expect" &&
+	test-tool ref-store main for-each-reflog-ent $m >actual &&
+	test_cmp actual expect
 '
 
 test_expect_success 'set up for querying the reflog' '
@@ -467,7 +466,8 @@
 $h_FIXED $h_MERGED $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117151100 +0000	commit (merge): Merged initial commit and a later commit.
 EOF
 test_expect_success 'git commit logged updates' '
-	test_cmp expect .git/logs/$m
+	test-tool ref-store main for-each-reflog-ent $m >actual &&
+	test_cmp expect actual
 '
 unset h_TEST h_OTHER h_FIXED h_MERGED
 
@@ -1368,7 +1368,7 @@
 (
 	for i in $(test_seq 33)
 	do
-		echo "create refs/heads/$i HEAD"
+		echo "create refs/heads/$i HEAD" || exit 1
 	done >large_input &&
 	run_with_limited_open_files git update-ref --stdin <large_input &&
 	git rev-parse --verify -q refs/heads/33
@@ -1379,7 +1379,7 @@
 (
 	for i in $(test_seq 33)
 	do
-		echo "delete refs/heads/$i HEAD"
+		echo "delete refs/heads/$i HEAD" || exit 1
 	done >large_input &&
 	run_with_limited_open_files git update-ref --stdin <large_input &&
 	test_must_fail git rev-parse --verify -q refs/heads/33
diff --git a/t/t1403-show-ref.sh b/t/t1403-show-ref.sh
index 17d3cc1..9252a58 100755
--- a/t/t1403-show-ref.sh
+++ b/t/t1403-show-ref.sh
@@ -4,6 +4,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
@@ -78,7 +79,7 @@
 test_expect_success 'show-ref -d' '
 	{
 		echo $(git rev-parse refs/tags/A) refs/tags/A &&
-		echo $(git rev-parse refs/tags/A^0) "refs/tags/A^{}"
+		echo $(git rev-parse refs/tags/A^0) "refs/tags/A^{}" &&
 		echo $(git rev-parse refs/tags/C) refs/tags/C
 	} >expect &&
 	git show-ref -d A C >actual &&
@@ -123,14 +124,14 @@
 test_expect_success 'show-ref --heads, --tags, --head, pattern' '
 	for branch in B main side
 	do
-		echo $(git rev-parse refs/heads/$branch) refs/heads/$branch
+		echo $(git rev-parse refs/heads/$branch) refs/heads/$branch || return 1
 	done >expect.heads &&
 	git show-ref --heads >actual &&
 	test_cmp expect.heads actual &&
 
 	for tag in A B C
 	do
-		echo $(git rev-parse refs/tags/$tag) refs/tags/$tag
+		echo $(git rev-parse refs/tags/$tag) refs/tags/$tag || return 1
 	done >expect.tags &&
 	git show-ref --tags >actual &&
 	test_cmp expect.tags actual &&
@@ -148,7 +149,7 @@
 
 	{
 		echo $(git rev-parse HEAD) HEAD &&
-		echo $(git rev-parse refs/heads/B) refs/heads/B
+		echo $(git rev-parse refs/heads/B) refs/heads/B &&
 		echo $(git rev-parse refs/tags/B) refs/tags/B
 	} >expect &&
 	git show-ref --head B >actual &&
@@ -156,8 +157,8 @@
 
 	{
 		echo $(git rev-parse HEAD) HEAD &&
-		echo $(git rev-parse refs/heads/B) refs/heads/B
-		echo $(git rev-parse refs/tags/B) refs/tags/B
+		echo $(git rev-parse refs/heads/B) refs/heads/B &&
+		echo $(git rev-parse refs/tags/B) refs/tags/B &&
 		echo $(git rev-parse refs/tags/B^0) "refs/tags/B^{}"
 	} >expect &&
 	git show-ref --head -d B >actual &&
diff --git a/t/t1404-update-ref-errors.sh b/t/t1404-update-ref-errors.sh
index b729c1f..13c2b43 100755
--- a/t/t1404-update-ref-errors.sh
+++ b/t/t1404-update-ref-errors.sh
@@ -261,69 +261,69 @@
 	git update-ref --stdin
 '
 
-test_expect_success 'D/F conflict prevents add long + delete short' '
+test_expect_success REFFILES 'D/F conflict prevents add long + delete short' '
 	df_test refs/df-al-ds --add-del foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents add short + delete long' '
+test_expect_success REFFILES 'D/F conflict prevents add short + delete long' '
 	df_test refs/df-as-dl --add-del foo foo/bar
 '
 
-test_expect_success 'D/F conflict prevents delete long + add short' '
+test_expect_success REFFILES 'D/F conflict prevents delete long + add short' '
 	df_test refs/df-dl-as --del-add foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents delete short + add long' '
+test_expect_success REFFILES 'D/F conflict prevents delete short + add long' '
 	df_test refs/df-ds-al --del-add foo foo/bar
 '
 
-test_expect_success 'D/F conflict prevents add long + delete short packed' '
+test_expect_success REFFILES 'D/F conflict prevents add long + delete short packed' '
 	df_test refs/df-al-dsp --pack --add-del foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents add short + delete long packed' '
+test_expect_success REFFILES 'D/F conflict prevents add short + delete long packed' '
 	df_test refs/df-as-dlp --pack --add-del foo foo/bar
 '
 
-test_expect_success 'D/F conflict prevents delete long packed + add short' '
+test_expect_success REFFILES 'D/F conflict prevents delete long packed + add short' '
 	df_test refs/df-dlp-as --pack --del-add foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents delete short packed + add long' '
+test_expect_success REFFILES 'D/F conflict prevents delete short packed + add long' '
 	df_test refs/df-dsp-al --pack --del-add foo foo/bar
 '
 
 # Try some combinations involving symbolic refs...
 
-test_expect_success 'D/F conflict prevents indirect add long + delete short' '
+test_expect_success REFFILES 'D/F conflict prevents indirect add long + delete short' '
 	df_test refs/df-ial-ds --sym-add --add-del foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents indirect add long + indirect delete short' '
+test_expect_success REFFILES 'D/F conflict prevents indirect add long + indirect delete short' '
 	df_test refs/df-ial-ids --sym-add --sym-del --add-del foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents indirect add short + indirect delete long' '
+test_expect_success REFFILES 'D/F conflict prevents indirect add short + indirect delete long' '
 	df_test refs/df-ias-idl --sym-add --sym-del --add-del foo foo/bar
 '
 
-test_expect_success 'D/F conflict prevents indirect delete long + indirect add short' '
+test_expect_success REFFILES 'D/F conflict prevents indirect delete long + indirect add short' '
 	df_test refs/df-idl-ias --sym-add --sym-del --del-add foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents indirect add long + delete short packed' '
+test_expect_success REFFILES 'D/F conflict prevents indirect add long + delete short packed' '
 	df_test refs/df-ial-dsp --sym-add --pack --add-del foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents indirect add long + indirect delete short packed' '
+test_expect_success REFFILES 'D/F conflict prevents indirect add long + indirect delete short packed' '
 	df_test refs/df-ial-idsp --sym-add --sym-del --pack --add-del foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents add long + indirect delete short packed' '
+test_expect_success REFFILES 'D/F conflict prevents add long + indirect delete short packed' '
 	df_test refs/df-al-idsp --sym-del --pack --add-del foo/bar foo
 '
 
-test_expect_success 'D/F conflict prevents indirect delete long packed + indirect add short' '
+test_expect_success REFFILES 'D/F conflict prevents indirect delete long packed + indirect add short' '
 	df_test refs/df-idlp-ias --sym-add --sym-del --pack --del-add foo/bar foo
 '
 
diff --git a/t/t1405-main-ref-store.sh b/t/t1405-main-ref-store.sh
index 49718b7..1a3ee88 100755
--- a/t/t1405-main-ref-store.sh
+++ b/t/t1405-main-ref-store.sh
@@ -17,8 +17,7 @@
 test_expect_success REFFILES 'pack_refs(PACK_REFS_ALL | PACK_REFS_PRUNE)' '
 	N=`find .git/refs -type f | wc -l` &&
 	test "$N" != 0 &&
-	ALL_OR_PRUNE_FLAG=3 &&
-	$RUN pack-refs ${ALL_OR_PRUNE_FLAG} &&
+	$RUN pack-refs PACK_REFS_PRUNE,PACK_REFS_ALL &&
 	N=`find .git/refs -type f` &&
 	test -z "$N"
 '
@@ -35,8 +34,7 @@
 	git rev-parse FOO -- &&
 	git rev-parse refs/tags/new-tag -- &&
 	m=$(git rev-parse main) &&
-	REF_NO_DEREF=1 &&
-	$RUN delete-refs $REF_NO_DEREF nothing FOO refs/tags/new-tag &&
+	$RUN delete-refs REF_NO_DEREF nothing FOO refs/tags/new-tag &&
 	test_must_fail git rev-parse --symbolic-full-name FOO &&
 	test_must_fail git rev-parse FOO -- &&
 	test_must_fail git rev-parse refs/tags/new-tag --
@@ -89,13 +87,13 @@
 test_expect_success 'for_each_reflog_ent()' '
 	$RUN for-each-reflog-ent HEAD >actual &&
 	head -n1 actual | grep one &&
-	tail -n2 actual | head -n1 | grep recreate-main
+	tail -n1 actual | grep recreate-main
 '
 
 test_expect_success 'for_each_reflog_ent_reverse()' '
 	$RUN for-each-reflog-ent-reverse HEAD >actual &&
 	head -n1 actual | grep recreate-main &&
-	tail -n2 actual | head -n1 | grep one
+	tail -n1 actual | grep one
 '
 
 test_expect_success 'reflog_exists(HEAD)' '
@@ -108,7 +106,7 @@
 '
 
 test_expect_success 'create-reflog(HEAD)' '
-	$RUN create-reflog HEAD 1 &&
+	$RUN create-reflog HEAD &&
 	git reflog exists HEAD
 '
 
diff --git a/t/t1406-submodule-ref-store.sh b/t/t1406-submodule-ref-store.sh
index 0a87058..e6a7f73 100755
--- a/t/t1406-submodule-ref-store.sh
+++ b/t/t1406-submodule-ref-store.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 RUN="test-tool ref-store submodule:sub"
@@ -74,13 +75,13 @@
 test_expect_success 'for_each_reflog_ent()' '
 	$RUN for-each-reflog-ent HEAD >actual &&
 	head -n1 actual | grep first &&
-	tail -n2 actual | head -n1 | grep main.to.new
+	tail -n1 actual | grep main.to.new
 '
 
 test_expect_success 'for_each_reflog_ent_reverse()' '
 	$RUN for-each-reflog-ent-reverse HEAD >actual &&
 	head -n1 actual | grep main.to.new &&
-	tail -n2 actual | head -n1 | grep first
+	tail -n1 actual | grep first
 '
 
 test_expect_success 'reflog_exists(HEAD)' '
@@ -92,7 +93,7 @@
 '
 
 test_expect_success 'create-reflog() not allowed' '
-	test_must_fail $RUN create-reflog HEAD 1
+	test_must_fail $RUN create-reflog HEAD
 '
 
 test_done
diff --git a/t/t1410-reflog.sh b/t/t1410-reflog.sh
index d42f067..d7ddf76 100755
--- a/t/t1410-reflog.sh
+++ b/t/t1410-reflog.sh
@@ -349,12 +349,12 @@
 		printf "$zf%02d $zf%02d %s\t" $i $(($i+1)) "$ident" &&
 		if test $i = 75; then
 			for j in $(test_seq 1 89); do
-				printf X
+				printf X || return 1
 			done
 		else
 			printf X
 		fi &&
-		printf "\n"
+		printf "\n" || return 1
 	done >.git/logs/refs/heads/reflogskip &&
 	git rev-parse reflogskip@{73} >actual &&
 	echo ${zf}03 >expect &&
diff --git a/t/t1417-reflog-updateref.sh b/t/t1417-reflog-updateref.sh
new file mode 100755
index 0000000..14f13b5
--- /dev/null
+++ b/t/t1417-reflog-updateref.sh
@@ -0,0 +1,65 @@
+#!/bin/sh
+
+test_description='git reflog --updateref'
+
+TEST_PASSES_SANITIZE_LEAK=true
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git init -b main repo &&
+	(
+		cd repo &&
+
+		test_commit A &&
+		test_commit B &&
+		test_commit C &&
+
+		cp .git/logs/HEAD HEAD.old &&
+		git reset --hard HEAD~ &&
+		cp HEAD.old .git/logs/HEAD
+	)
+'
+
+test_reflog_updateref () {
+	exp=$1
+	shift
+	args="$@"
+
+	test_expect_success REFFILES "get '$exp' with '$args'"  '
+		test_when_finished "rm -rf copy" &&
+		cp -R repo copy &&
+
+		(
+			cd copy &&
+
+			$args &&
+			git rev-parse $exp >expect &&
+			git rev-parse HEAD >actual &&
+
+			test_cmp expect actual
+		)
+	'
+}
+
+test_reflog_updateref B git reflog delete --updateref HEAD@{0}
+test_reflog_updateref B git reflog delete --updateref HEAD@{1}
+test_reflog_updateref C git reflog delete --updateref main@{0}
+test_reflog_updateref B git reflog delete --updateref main@{1}
+test_reflog_updateref B git reflog delete --updateref --rewrite HEAD@{0}
+test_reflog_updateref B git reflog delete --updateref --rewrite HEAD@{1}
+test_reflog_updateref C git reflog delete --updateref --rewrite main@{0}
+test_reflog_updateref B git reflog delete --updateref --rewrite main@{1}
+test_reflog_updateref B test_must_fail git reflog expire  HEAD@{0}
+test_reflog_updateref B test_must_fail git reflog expire  HEAD@{1}
+test_reflog_updateref B test_must_fail git reflog expire  main@{0}
+test_reflog_updateref B test_must_fail git reflog expire  main@{1}
+test_reflog_updateref B test_must_fail git reflog expire --updateref HEAD@{0}
+test_reflog_updateref B test_must_fail git reflog expire --updateref HEAD@{1}
+test_reflog_updateref B test_must_fail git reflog expire --updateref main@{0}
+test_reflog_updateref B test_must_fail git reflog expire --updateref main@{1}
+test_reflog_updateref B test_must_fail git reflog expire --updateref --rewrite HEAD@{0}
+test_reflog_updateref B test_must_fail git reflog expire --updateref --rewrite HEAD@{1}
+test_reflog_updateref B test_must_fail git reflog expire --updateref --rewrite main@{0}
+test_reflog_updateref B test_must_fail git reflog expire --updateref --rewrite main@{1}
+
+test_done
diff --git a/t/t1420-lost-found.sh b/t/t1420-lost-found.sh
index dc9e402..dbe15a0 100755
--- a/t/t1420-lost-found.sh
+++ b/t/t1420-lost-found.sh
@@ -4,6 +4,8 @@
 #
 
 test_description='Test fsck --lost-found'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t1430-bad-ref-name.sh b/t/t1430-bad-ref-name.sh
index 4c77cf8..ff1c967 100755
--- a/t/t1430-bad-ref-name.sh
+++ b/t/t1430-bad-ref-name.sh
@@ -9,7 +9,8 @@
 
 test_expect_success setup '
 	test_commit one &&
-	test_commit two
+	test_commit two &&
+	main_sha1=$(git rev-parse refs/heads/main)
 '
 
 test_expect_success 'fast-import: fail on invalid branch name ".badbranchname"' '
@@ -43,16 +44,16 @@
 '
 
 test_expect_success 'git branch shows badly named ref as warning' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	git branch >output 2>error &&
 	test_i18ngrep -e "ignoring ref with broken name refs/heads/broken\.\.\.ref" error &&
 	! grep -e "broken\.\.\.ref" output
 '
 
 test_expect_success 'branch -d can delete badly named ref' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	git branch -d broken...ref &&
 	git branch >output 2>error &&
 	! grep -e "broken\.\.\.ref" error &&
@@ -60,8 +61,8 @@
 '
 
 test_expect_success 'branch -D can delete badly named ref' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	git branch -D broken...ref &&
 	git branch >output 2>error &&
 	! grep -e "broken\.\.\.ref" error &&
@@ -90,7 +91,7 @@
 '
 
 test_expect_success 'git branch cannot create a badly named ref' '
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	test_must_fail git branch broken...ref &&
 	git branch >output 2>error &&
 	! grep -e "broken\.\.\.ref" error &&
@@ -98,7 +99,7 @@
 '
 
 test_expect_success 'branch -m cannot rename to a bad ref name' '
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	test_might_fail git branch -D goodref &&
 	git branch goodref &&
 	test_must_fail git branch -m goodref broken...ref &&
@@ -109,8 +110,9 @@
 '
 
 test_expect_failure 'branch -m can rename from a bad ref name' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	git branch -m broken...ref renamed &&
 	test_cmp_rev main renamed &&
 	git branch >output 2>error &&
@@ -119,7 +121,7 @@
 '
 
 test_expect_success 'push cannot create a badly named ref' '
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	test_must_fail git push "file://$(pwd)" HEAD:refs/heads/broken...ref &&
 	git branch >output 2>error &&
 	! grep -e "broken\.\.\.ref" error &&
@@ -139,7 +141,7 @@
 		cd dest &&
 		test_commit two &&
 		git checkout --detach &&
-		cp .git/refs/heads/main .git/refs/heads/broken...ref
+		test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION
 	) &&
 	git -C src push --mirror "file://$top/dest" &&
 	git -C dest branch >output 2>error &&
@@ -148,11 +150,11 @@
 '
 
 test_expect_success 'rev-parse skips symref pointing to broken name' '
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	git branch shadow one &&
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	printf "ref: refs/heads/broken...ref\n" >.git/refs/tags/shadow &&
-	test_when_finished "rm -f .git/refs/tags/shadow" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	test-tool ref-store main create-symref refs/tags/shadow refs/heads/broken...ref msg &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/tags/shadow" &&
 	git rev-parse --verify one >expect &&
 	git rev-parse --verify shadow >actual 2>err &&
 	test_cmp expect actual &&
@@ -160,12 +162,12 @@
 '
 
 test_expect_success 'for-each-ref emits warnings for broken names' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	printf "ref: refs/heads/broken...ref\n" >.git/refs/heads/badname &&
-	test_when_finished "rm -f .git/refs/heads/badname" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
 	printf "ref: refs/heads/main\n" >.git/refs/heads/broken...symref &&
-	test_when_finished "rm -f .git/refs/heads/broken...symref" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	git for-each-ref >output 2>error &&
 	! grep -e "broken\.\.\.ref" output &&
 	! grep -e "badname" output &&
@@ -176,8 +178,8 @@
 '
 
 test_expect_success 'update-ref -d can delete broken name' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	git update-ref -d refs/heads/broken...ref >output 2>error &&
 	test_must_be_empty output &&
 	test_must_be_empty error &&
@@ -187,8 +189,8 @@
 '
 
 test_expect_success 'branch -d can delete broken name' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	git branch -d broken...ref >output 2>error &&
 	test_i18ngrep "Deleted branch broken...ref (was broken)" output &&
 	test_must_be_empty error &&
@@ -198,10 +200,11 @@
 '
 
 test_expect_success 'update-ref --no-deref -d can delete symref to broken name' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
-	printf "ref: refs/heads/broken...ref\n" >.git/refs/heads/badname &&
-	test_when_finished "rm -f .git/refs/heads/badname" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
+	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
 	git update-ref --no-deref -d refs/heads/badname >output 2>error &&
 	test_path_is_missing .git/refs/heads/badname &&
 	test_must_be_empty output &&
@@ -209,10 +212,10 @@
 '
 
 test_expect_success 'branch -d can delete symref to broken name' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
-	printf "ref: refs/heads/broken...ref\n" >.git/refs/heads/badname &&
-	test_when_finished "rm -f .git/refs/heads/badname" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
+	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
 	git branch -d badname >output 2>error &&
 	test_path_is_missing .git/refs/heads/badname &&
 	test_i18ngrep "Deleted branch badname (was refs/heads/broken\.\.\.ref)" output &&
@@ -220,8 +223,8 @@
 '
 
 test_expect_success 'update-ref --no-deref -d can delete dangling symref to broken name' '
-	printf "ref: refs/heads/broken...ref\n" >.git/refs/heads/badname &&
-	test_when_finished "rm -f .git/refs/heads/badname" &&
+	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
 	git update-ref --no-deref -d refs/heads/badname >output 2>error &&
 	test_path_is_missing .git/refs/heads/badname &&
 	test_must_be_empty output &&
@@ -229,8 +232,8 @@
 '
 
 test_expect_success 'branch -d can delete dangling symref to broken name' '
-	printf "ref: refs/heads/broken...ref\n" >.git/refs/heads/badname &&
-	test_when_finished "rm -f .git/refs/heads/badname" &&
+	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
 	git branch -d badname >output 2>error &&
 	test_path_is_missing .git/refs/heads/badname &&
 	test_i18ngrep "Deleted branch badname (was refs/heads/broken\.\.\.ref)" output &&
@@ -238,10 +241,10 @@
 '
 
 test_expect_success 'update-ref -d can delete broken name through symref' '
-	cp .git/refs/heads/main .git/refs/heads/broken...ref &&
-	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
-	printf "ref: refs/heads/broken...ref\n" >.git/refs/heads/badname &&
-	test_when_finished "rm -f .git/refs/heads/badname" &&
+	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
+	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
 	git update-ref -d refs/heads/badname >output 2>error &&
 	test_path_is_missing .git/refs/heads/broken...ref &&
 	test_must_be_empty output &&
@@ -250,7 +253,7 @@
 
 test_expect_success 'update-ref --no-deref -d can delete symref with broken name' '
 	printf "ref: refs/heads/main\n" >.git/refs/heads/broken...symref &&
-	test_when_finished "rm -f .git/refs/heads/broken...symref" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	git update-ref --no-deref -d refs/heads/broken...symref >output 2>error &&
 	test_path_is_missing .git/refs/heads/broken...symref &&
 	test_must_be_empty output &&
@@ -259,7 +262,7 @@
 
 test_expect_success 'branch -d can delete symref with broken name' '
 	printf "ref: refs/heads/main\n" >.git/refs/heads/broken...symref &&
-	test_when_finished "rm -f .git/refs/heads/broken...symref" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	git branch -d broken...symref >output 2>error &&
 	test_path_is_missing .git/refs/heads/broken...symref &&
 	test_i18ngrep "Deleted branch broken...symref (was refs/heads/main)" output &&
@@ -268,7 +271,7 @@
 
 test_expect_success 'update-ref --no-deref -d can delete dangling symref with broken name' '
 	printf "ref: refs/heads/idonotexist\n" >.git/refs/heads/broken...symref &&
-	test_when_finished "rm -f .git/refs/heads/broken...symref" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	git update-ref --no-deref -d refs/heads/broken...symref >output 2>error &&
 	test_path_is_missing .git/refs/heads/broken...symref &&
 	test_must_be_empty output &&
@@ -277,7 +280,7 @@
 
 test_expect_success 'branch -d can delete dangling symref with broken name' '
 	printf "ref: refs/heads/idonotexist\n" >.git/refs/heads/broken...symref &&
-	test_when_finished "rm -f .git/refs/heads/broken...symref" &&
+	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	git branch -d broken...symref >output 2>error &&
 	test_path_is_missing .git/refs/heads/broken...symref &&
 	test_i18ngrep "Deleted branch broken...symref (was refs/heads/idonotexist)" output &&
diff --git a/t/t1503-rev-parse-verify.sh b/t/t1503-rev-parse-verify.sh
index 4095861..94fe413 100755
--- a/t/t1503-rev-parse-verify.sh
+++ b/t/t1503-rev-parse-verify.sh
@@ -9,6 +9,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 add_line_into_file()
diff --git a/t/t1505-rev-parse-last.sh b/t/t1505-rev-parse-last.sh
index 2803ca9..4a5758f 100755
--- a/t/t1505-rev-parse-last.sh
+++ b/t/t1505-rev-parse-last.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 
diff --git a/t/t1506-rev-parse-diagnosis.sh b/t/t1506-rev-parse-diagnosis.sh
index 65a154a..18688ca 100755
--- a/t/t1506-rev-parse-diagnosis.sh
+++ b/t/t1506-rev-parse-diagnosis.sh
@@ -7,6 +7,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_did_you_mean ()
diff --git a/t/t1512-rev-parse-disambiguation.sh b/t/t1512-rev-parse-disambiguation.sh
index 7891a6b..b0119bf 100755
--- a/t/t1512-rev-parse-disambiguation.sh
+++ b/t/t1512-rev-parse-disambiguation.sh
@@ -34,10 +34,7 @@
 test_expect_success 'blob and tree' '
 	test_tick &&
 	(
-		for i in 0 1 2 3 4 5 6 7 8 9
-		do
-			echo $i
-		done &&
+		test_write_lines 0 1 2 3 4 5 6 7 8 9 &&
 		echo &&
 		echo b1rwzyc3
 	) >a0blgqsjc &&
@@ -204,10 +201,7 @@
 	git checkout v1.0.0^0 &&
 	git mv a0blgqsjc f5518nwu &&
 
-	for i in h62xsjeu j08bekfvt kg7xflhm
-	do
-		echo $i
-	done >>f5518nwu &&
+	test_write_lines h62xsjeu j08bekfvt kg7xflhm >>f5518nwu &&
 	git add f5518nwu &&
 
 	test_tick &&
@@ -387,7 +381,7 @@
 	do
 		grep $type objects >$type.objects &&
 		sort $type.objects >$type.objects.sorted &&
-		test_cmp $type.objects.sorted $type.objects
+		test_cmp $type.objects.sorted $type.objects || return 1
 	done
 '
 
diff --git a/t/t1513-rev-parse-prefix.sh b/t/t1513-rev-parse-prefix.sh
index 5f437be..ba43387 100755
--- a/t/t1513-rev-parse-prefix.sh
+++ b/t/t1513-rev-parse-prefix.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t1515-rev-parse-outside-repo.sh b/t/t1515-rev-parse-outside-repo.sh
index 3ec2971..cdb26a3 100755
--- a/t/t1515-rev-parse-outside-repo.sh
+++ b/t/t1515-rev-parse-outside-repo.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='check that certain rev-parse options work outside repo'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'set up non-repo directory' '
diff --git a/t/t1600-index.sh b/t/t1600-index.sh
index 46329c4..010989f 100755
--- a/t/t1600-index.sh
+++ b/t/t1600-index.sh
@@ -2,6 +2,7 @@
 
 test_description='index file specific tests'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 sane_unset GIT_TEST_SPLIT_INDEX
diff --git a/t/t1700-split-index.sh b/t/t1700-split-index.sh
index decd252..b4ab166 100755
--- a/t/t1700-split-index.sh
+++ b/t/t1700-split-index.sh
@@ -48,10 +48,10 @@
 	# NEEDSWORK: Stop hard-coding checksums.
 	if test "$indexversion" = "4"
 	then
-		own=$(test_oid own_v4)
+		own=$(test_oid own_v4) &&
 		base=$(test_oid base_v4)
 	else
-		own=$(test_oid own_v3)
+		own=$(test_oid own_v3) &&
 		base=$(test_oid base_v3)
 	fi &&
 
diff --git a/t/t2000-conflict-when-checking-files-out.sh b/t/t2000-conflict-when-checking-files-out.sh
index f18616a..79fc97f 100755
--- a/t/t2000-conflict-when-checking-files-out.sh
+++ b/t/t2000-conflict-when-checking-files-out.sh
@@ -21,6 +21,7 @@
 # path1 is occupied by a non-directory.  With "-f" flag, it should remove
 # the conflicting paths and succeed.
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 show_files() {
diff --git a/t/t2004-checkout-cache-temp.sh b/t/t2004-checkout-cache-temp.sh
index 9bb503a..b16d69c 100755
--- a/t/t2004-checkout-cache-temp.sh
+++ b/t/t2004-checkout-cache-temp.sh
@@ -57,7 +57,7 @@
 		test $(grep $f actual | cut "-d	" -f2) = $f &&
 		p=$(grep $f actual | cut "-d	" -f1) &&
 		test -f $p &&
-		test $(cat $p) = tree1$f
+		test $(cat $p) = tree1$f || return 1
 	done
 '
 
@@ -85,7 +85,7 @@
 		test $(grep $f actual | cut "-d	" -f2) = $f &&
 		p=$(grep $f actual | cut "-d	" -f1) &&
 		test -f $p &&
-		test $(cat $p) = tree2$f
+		test $(cat $p) = tree2$f || return 1
 	done
 '
 
diff --git a/t/t2007-checkout-symlink.sh b/t/t2007-checkout-symlink.sh
index 6f0b90c..bd9e9e7 100755
--- a/t/t2007-checkout-symlink.sh
+++ b/t/t2007-checkout-symlink.sh
@@ -7,6 +7,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t2008-checkout-subdir.sh b/t/t2008-checkout-subdir.sh
index eadb943..8a518a4 100755
--- a/t/t2008-checkout-subdir.sh
+++ b/t/t2008-checkout-subdir.sh
@@ -4,6 +4,7 @@
 
 test_description='git checkout from subdirectories'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t2009-checkout-statinfo.sh b/t/t2009-checkout-statinfo.sh
index b054063..71195dd 100755
--- a/t/t2009-checkout-statinfo.sh
+++ b/t/t2009-checkout-statinfo.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t2010-checkout-ambiguous.sh b/t/t2010-checkout-ambiguous.sh
index 6e87573..9d4b375 100755
--- a/t/t2010-checkout-ambiguous.sh
+++ b/t/t2010-checkout-ambiguous.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t2011-checkout-invalid-head.sh b/t/t2011-checkout-invalid-head.sh
index e52022e..d9997e7 100755
--- a/t/t2011-checkout-invalid-head.sh
+++ b/t/t2011-checkout-invalid-head.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t2012-checkout-last.sh b/t/t2012-checkout-last.sh
index 0e7d47a..42601d5 100755
--- a/t/t2012-checkout-last.sh
+++ b/t/t2012-checkout-last.sh
@@ -49,14 +49,14 @@
 test_expect_success 'more switches' '
 	for i in 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
 	do
-		git checkout -b branch$i
+		git checkout -b branch$i || return 1
 	done
 '
 
 more_switches () {
 	for i in 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
 	do
-		git checkout branch$i
+		git checkout branch$i || return 1
 	done
 }
 
diff --git a/t/t2014-checkout-switch.sh b/t/t2014-checkout-switch.sh
index ccfb147..c138bdd 100755
--- a/t/t2014-checkout-switch.sh
+++ b/t/t2014-checkout-switch.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='Peter MacMillan'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t2017-checkout-orphan.sh b/t/t2017-checkout-orphan.sh
index 88d6992..947d158 100755
--- a/t/t2017-checkout-orphan.sh
+++ b/t/t2017-checkout-orphan.sh
@@ -10,6 +10,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 TEST_FILE=foo
@@ -62,8 +63,17 @@
 	git checkout main &&
 	git config branch.autosetupmerge always &&
 	git checkout --orphan gamma &&
-	test -z "$(git config branch.gamma.merge)" &&
+	test_cmp_config "" --default "" branch.gamma.merge &&
 	test refs/heads/gamma = "$(git symbolic-ref HEAD)" &&
+	test_must_fail git rev-parse --verify HEAD^ &&
+	git checkout main &&
+	git config branch.autosetupmerge inherit &&
+	git checkout --orphan eta &&
+	test_cmp_config "" --default "" branch.eta.merge &&
+	test_cmp_config "" --default "" branch.eta.remote &&
+	echo refs/heads/eta >expected &&
+	git symbolic-ref HEAD >actual &&
+	test_cmp expected actual &&
 	test_must_fail git rev-parse --verify HEAD^
 '
 
diff --git a/t/t2018-checkout-branch.sh b/t/t2018-checkout-branch.sh
index 93be1c0..3e93506 100755
--- a/t/t2018-checkout-branch.sh
+++ b/t/t2018-checkout-branch.sh
@@ -148,7 +148,7 @@
 test_expect_success 'checkout -b to @{-1} fails with the right branch name' '
 	git checkout branch1 &&
 	git checkout branch2 &&
-	echo  >expect "fatal: A branch named '\''branch1'\'' already exists." &&
+	echo  >expect "fatal: a branch named '\''branch1'\'' already exists" &&
 	test_must_fail git checkout -b @{-1} 2>actual &&
 	test_cmp expect actual
 '
diff --git a/t/t2019-checkout-ambiguous-ref.sh b/t/t2019-checkout-ambiguous-ref.sh
index b99d519..2c8c926 100755
--- a/t/t2019-checkout-ambiguous-ref.sh
+++ b/t/t2019-checkout-ambiguous-ref.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='checkout handling of ambiguous (branch/tag) refs'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup ambiguous refs' '
diff --git a/t/t2021-checkout-overwrite.sh b/t/t2021-checkout-overwrite.sh
index 660132f..713c3fa 100755
--- a/t/t2021-checkout-overwrite.sh
+++ b/t/t2021-checkout-overwrite.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='checkout must not overwrite an untracked objects'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t2022-checkout-paths.sh b/t/t2022-checkout-paths.sh
index c49ba7f..f1b709d 100755
--- a/t/t2022-checkout-paths.sh
+++ b/t/t2022-checkout-paths.sh
@@ -4,6 +4,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t2025-checkout-no-overlay.sh b/t/t2025-checkout-no-overlay.sh
index fa9e098..8f13341 100755
--- a/t/t2025-checkout-no-overlay.sh
+++ b/t/t2025-checkout-no-overlay.sh
@@ -25,7 +25,7 @@
 
 test_expect_success 'checkout -p --overlay is disallowed' '
 	test_must_fail git checkout -p --overlay HEAD 2>actual &&
-	test_i18ngrep "fatal: -p and --overlay are mutually exclusive" actual
+	test_i18ngrep "fatal: options .-p. and .--overlay. cannot be used together" actual
 '
 
 test_expect_success '--no-overlay --theirs with D/F conflict deletes file' '
diff --git a/t/t2026-checkout-pathspec-file.sh b/t/t2026-checkout-pathspec-file.sh
index 43d31d7..9c651ae 100755
--- a/t/t2026-checkout-pathspec-file.sh
+++ b/t/t2026-checkout-pathspec-file.sh
@@ -2,6 +2,7 @@
 
 test_description='checkout --pathspec-from-file'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_tick
@@ -148,16 +149,16 @@
 	echo fileA.t >list &&
 
 	test_must_fail git checkout --pathspec-from-file=list --detach 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --detach" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--detach. cannot be used together" err &&
 
 	test_must_fail git checkout --pathspec-from-file=list --patch 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --patch" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--patch. cannot be used together" err &&
 
 	test_must_fail git checkout --pathspec-from-file=list -- fileA.t 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with pathspec arguments" err &&
+	test_i18ngrep -e ".--pathspec-from-file. and pathspec arguments cannot be used together" err &&
 
 	test_must_fail git checkout --pathspec-file-nul 2>err &&
-	test_i18ngrep -e "--pathspec-file-nul requires --pathspec-from-file" err
+	test_i18ngrep -e "the option .--pathspec-file-nul. requires .--pathspec-from-file." err
 '
 
 test_done
diff --git a/t/t2027-checkout-track.sh b/t/t2027-checkout-track.sh
index 4453741..dca35aa 100755
--- a/t/t2027-checkout-track.sh
+++ b/t/t2027-checkout-track.sh
@@ -24,4 +24,27 @@
 	test_i18ngrep "cannot be used with updating paths" err
 '
 
+test_expect_success 'checkout --track -b overrides autoSetupMerge=inherit' '
+	# Set up tracking config on main
+	test_config branch.main.remote origin &&
+	test_config branch.main.merge refs/heads/some-branch &&
+	test_config branch.autoSetupMerge inherit &&
+	# With --track=inherit, we copy the tracking config from main
+	git checkout --track=inherit -b b1 main &&
+	test_cmp_config origin branch.b1.remote &&
+	test_cmp_config refs/heads/some-branch branch.b1.merge &&
+	# With branch.autoSetupMerge=inherit, we do the same
+	git checkout -b b2 main &&
+	test_cmp_config origin branch.b2.remote &&
+	test_cmp_config refs/heads/some-branch branch.b2.merge &&
+	# But --track overrides this
+	git checkout --track -b b3 main &&
+	test_cmp_config . branch.b3.remote &&
+	test_cmp_config refs/heads/main branch.b3.merge &&
+	# And --track=direct does as well
+	git checkout --track=direct -b b4 main &&
+	test_cmp_config . branch.b4.remote &&
+	test_cmp_config refs/heads/main branch.b4.merge
+'
+
 test_done
diff --git a/t/t2060-switch.sh b/t/t2060-switch.sh
index 9bc6a3a..ebb961b 100755
--- a/t/t2060-switch.sh
+++ b/t/t2060-switch.sh
@@ -107,4 +107,32 @@
 	test_must_fail git switch -d @^
 '
 
+test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
+	# default config does not copy tracking info
+	git switch -c foo-no-inherit foo &&
+	test_cmp_config "" --default "" branch.foo-no-inherit.remote &&
+	test_cmp_config "" --default "" branch.foo-no-inherit.merge &&
+	# with --track=inherit, we copy tracking info from foo
+	git switch --track=inherit -c foo2 foo &&
+	test_cmp_config origin branch.foo2.remote &&
+	test_cmp_config refs/heads/foo branch.foo2.merge &&
+	# with autoSetupMerge=inherit, we do the same
+	test_config branch.autoSetupMerge inherit &&
+	git switch -c foo3 foo &&
+	test_cmp_config origin branch.foo3.remote &&
+	test_cmp_config refs/heads/foo branch.foo3.merge &&
+	# with --track, we override autoSetupMerge
+	git switch --track -c foo4 foo &&
+	test_cmp_config . branch.foo4.remote &&
+	test_cmp_config refs/heads/foo branch.foo4.merge &&
+	# and --track=direct does as well
+	git switch --track=direct -c foo5 foo &&
+	test_cmp_config . branch.foo5.remote &&
+	test_cmp_config refs/heads/foo branch.foo5.merge &&
+	# no tracking info to inherit from main
+	git switch -c main2 main &&
+	test_cmp_config "" --default "" branch.main2.remote &&
+	test_cmp_config "" --default "" branch.main2.merge
+'
+
 test_done
diff --git a/t/t2072-restore-pathspec-file.sh b/t/t2072-restore-pathspec-file.sh
index b48345b..c22669b 100755
--- a/t/t2072-restore-pathspec-file.sh
+++ b/t/t2072-restore-pathspec-file.sh
@@ -152,13 +152,13 @@
 	>empty_list &&
 
 	test_must_fail git restore --pathspec-from-file=list --patch --source=HEAD^1 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --patch" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--patch. cannot be used together" err &&
 
 	test_must_fail git restore --pathspec-from-file=list --source=HEAD^1 -- fileA.t 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with pathspec arguments" err &&
+	test_i18ngrep -e ".--pathspec-from-file. and pathspec arguments cannot be used together" err &&
 
 	test_must_fail git restore --pathspec-file-nul --source=HEAD^1 2>err &&
-	test_i18ngrep -e "--pathspec-file-nul requires --pathspec-from-file" err &&
+	test_i18ngrep -e "the option .--pathspec-file-nul. requires .--pathspec-from-file." err &&
 
 	test_must_fail git restore --pathspec-from-file=empty_list --source=HEAD^1 2>err &&
 	test_i18ngrep -e "you must specify path(s) to restore" err
diff --git a/t/t2100-update-cache-badpath.sh b/t/t2100-update-cache-badpath.sh
index 2df3fdd..7915e7b 100755
--- a/t/t2100-update-cache-badpath.sh
+++ b/t/t2100-update-cache-badpath.sh
@@ -22,6 +22,7 @@
 All of the attempts should fail.
 '
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 mkdir path2 path3
diff --git a/t/t2101-update-index-reupdate.sh b/t/t2101-update-index-reupdate.sh
index 6c32d42..e3c7acd 100755
--- a/t/t2101-update-index-reupdate.sh
+++ b/t/t2101-update-index-reupdate.sh
@@ -6,6 +6,7 @@
 test_description='git update-index --again test.
 '
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'update-index --add' '
diff --git a/t/t2102-update-index-symlinks.sh b/t/t2102-update-index-symlinks.sh
index 22f2c73..c49cdfb 100755
--- a/t/t2102-update-index-symlinks.sh
+++ b/t/t2102-update-index-symlinks.sh
@@ -8,6 +8,7 @@
 This tests that git update-index keeps the symbolic link property
 even if a plain file is in the working tree if core.symlinks is false.'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success \
@@ -25,7 +26,7 @@
 'the index entry must still be a symbolic link' '
 case "$(git ls-files --stage --cached symlink)" in
 120000" "*symlink) echo pass;;
-*) echo fail; git ls-files --stage --cached symlink; (exit 1);;
+*) echo fail; git ls-files --stage --cached symlink; false;;
 esac'
 
 test_done
diff --git a/t/t2103-update-index-ignore-missing.sh b/t/t2103-update-index-ignore-missing.sh
index 0114f05..e9451cd 100755
--- a/t/t2103-update-index-ignore-missing.sh
+++ b/t/t2103-update-index-ignore-missing.sh
@@ -2,6 +2,7 @@
 
 test_description='update-index with options'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success basics '
@@ -23,7 +24,7 @@
 	test_cmp expect actual &&
 
 	git update-index --add one two three &&
-	for i in one three two; do echo $i; done >expect &&
+	test_write_lines one three two >expect &&
 	git ls-files >actual &&
 	test_cmp expect actual &&
 
diff --git a/t/t2104-update-index-skip-worktree.sh b/t/t2104-update-index-skip-worktree.sh
index 30666fc..b8686aa 100755
--- a/t/t2104-update-index-skip-worktree.sh
+++ b/t/t2104-update-index-skip-worktree.sh
@@ -5,6 +5,7 @@
 
 test_description='skip-worktree bit test'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 sane_unset GIT_TEST_SPLIT_INDEX
diff --git a/t/t2105-update-index-gitfile.sh b/t/t2105-update-index-gitfile.sh
index a7f3d47..963ebe7 100755
--- a/t/t2105-update-index-gitfile.sh
+++ b/t/t2105-update-index-gitfile.sh
@@ -6,6 +6,7 @@
 test_description='git update-index for gitlink to .git file.
 '
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'submodule with absolute .git file' '
diff --git a/t/t2106-update-index-assume-unchanged.sh b/t/t2106-update-index-assume-unchanged.sh
index 2d450da..d943ddf 100755
--- a/t/t2106-update-index-assume-unchanged.sh
+++ b/t/t2106-update-index-assume-unchanged.sh
@@ -3,6 +3,7 @@
 test_description='git update-index --assume-unchanged test.
 '
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t2200-add-update.sh b/t/t2200-add-update.sh
index 94c4cb0..acd3650 100755
--- a/t/t2200-add-update.sh
+++ b/t/t2200-add-update.sh
@@ -14,6 +14,7 @@
 Also tested are "git add -u" without limiting, and "git add -u"
 without contents changes, and other conditions'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
@@ -150,13 +151,13 @@
 	{
 		for path in path1 path2
 		do
-			echo "100644 $one 1	$path"
-			echo "100644 $two 2	$path"
-			echo "100644 $three 3	$path"
-		done
-		echo "100644 $one 1	path3"
-		echo "100644 $one 1	path4"
-		echo "100644 $one 3	path5"
+			echo "100644 $one 1	$path" &&
+			echo "100644 $two 2	$path" &&
+			echo "100644 $three 3	$path" || return 1
+		done &&
+		echo "100644 $one 1	path3" &&
+		echo "100644 $one 1	path4" &&
+		echo "100644 $one 3	path5" &&
 		echo "100644 $one 3	path6"
 	} |
 	git update-index --index-info &&
@@ -173,8 +174,8 @@
 	git add -u &&
 	git ls-files -s path1 path2 path3 path4 path5 path6 >actual &&
 	{
-		echo "100644 $three 0	path1"
-		echo "100644 $two 0	path3"
+		echo "100644 $three 0	path1" &&
+		echo "100644 $two 0	path3" &&
 		echo "100644 $two 0	path5"
 	} >expect &&
 	test_cmp expect actual
diff --git a/t/t2201-add-update-typechange.sh b/t/t2201-add-update-typechange.sh
index a4eec0a..dba62d6 100755
--- a/t/t2201-add-update-typechange.sh
+++ b/t/t2201-add-update-typechange.sh
@@ -2,6 +2,7 @@
 
 test_description='more git add -u'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
@@ -97,17 +98,17 @@
 		"
 	} >expect &&
 	{
-		cat expect
-		echo ":100644 160000 $_empty $ZERO_OID T	yonk"
+		cat expect &&
+		echo ":100644 160000 $_empty $ZERO_OID T	yonk" &&
 		echo ":100644 000000 $_empty $ZERO_OID D	zifmia"
 	} >expect-files &&
 	{
-		cat expect
+		cat expect &&
 		echo ":000000 160000 $ZERO_OID $ZERO_OID A	yonk"
 	} >expect-index &&
 	{
-		echo "100644 $_empty 0	nitfol"
-		echo "160000 $yomin 0	yomin"
+		echo "100644 $_empty 0	nitfol" &&
+		echo "160000 $yomin 0	yomin" &&
 		echo "160000 $yonk 0	yonk"
 	} >expect-final
 '
diff --git a/t/t2202-add-addremove.sh b/t/t2202-add-addremove.sh
index 9ee6590..24c60bf 100755
--- a/t/t2202-add-addremove.sh
+++ b/t/t2202-add-addremove.sh
@@ -2,6 +2,7 @@
 
 test_description='git add --all'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t2203-add-intent.sh b/t/t2203-add-intent.sh
index cf0175a..db7ca55 100755
--- a/t/t2203-add-intent.sh
+++ b/t/t2203-add-intent.sh
@@ -116,7 +116,7 @@
 		mkdir 2 &&
 		for f in 1 2/1 2/2 3
 		do
-			echo "$f" >"$f"
+			echo "$f" >"$f" || return 1
 		done &&
 		git add 1 2/2 3 &&
 		git add -N 2/1 &&
diff --git a/t/t2204-add-ignored.sh b/t/t2204-add-ignored.sh
index 2e07365..89424ab 100755
--- a/t/t2204-add-ignored.sh
+++ b/t/t2204-add-ignored.sh
@@ -2,6 +2,7 @@
 
 test_description='giving ignored paths to git add'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t2401-worktree-prune.sh b/t/t2401-worktree-prune.sh
index a615d3b..3d28c7f 100755
--- a/t/t2401-worktree-prune.sh
+++ b/t/t2401-worktree-prune.sh
@@ -19,7 +19,7 @@
 test_expect_success 'prune files inside $GIT_DIR/worktrees' '
 	mkdir .git/worktrees &&
 	: >.git/worktrees/abc &&
-	git worktree prune --verbose >actual &&
+	git worktree prune --verbose 2>actual &&
 	cat >expect <<EOF &&
 Removing worktrees/abc: not a valid directory
 EOF
@@ -34,7 +34,7 @@
 	cat >expect <<EOF &&
 Removing worktrees/def: gitdir file does not exist
 EOF
-	git worktree prune --verbose >actual &&
+	git worktree prune --verbose 2>actual &&
 	test_cmp expect actual &&
 	! test -d .git/worktrees/def &&
 	! test -d .git/worktrees
@@ -45,7 +45,7 @@
 	: >.git/worktrees/def/def &&
 	: >.git/worktrees/def/gitdir &&
 	chmod u-r .git/worktrees/def/gitdir &&
-	git worktree prune --verbose >actual &&
+	git worktree prune --verbose 2>actual &&
 	test_i18ngrep "Removing worktrees/def: unable to read gitdir file" actual &&
 	! test -d .git/worktrees/def &&
 	! test -d .git/worktrees
@@ -55,7 +55,7 @@
 	mkdir -p .git/worktrees/def/abc &&
 	: >.git/worktrees/def/def &&
 	: >.git/worktrees/def/gitdir &&
-	git worktree prune --verbose >actual &&
+	git worktree prune --verbose 2>actual &&
 	test_i18ngrep "Removing worktrees/def: invalid gitdir file" actual &&
 	! test -d .git/worktrees/def &&
 	! test -d .git/worktrees
@@ -65,7 +65,7 @@
 	mkdir -p .git/worktrees/def/abc &&
 	: >.git/worktrees/def/def &&
 	echo "$(pwd)"/nowhere >.git/worktrees/def/gitdir &&
-	git worktree prune --verbose >actual &&
+	git worktree prune --verbose 2>actual &&
 	test_i18ngrep "Removing worktrees/def: gitdir file points to non-existent location" actual &&
 	! test -d .git/worktrees/def &&
 	! test -d .git/worktrees
@@ -101,7 +101,7 @@
 	git worktree add --detach w2 &&
 	sed "s/w2/w1/" .git/worktrees/w2/gitdir >.git/worktrees/w2/gitdir.new &&
 	mv .git/worktrees/w2/gitdir.new .git/worktrees/w2/gitdir &&
-	git worktree prune --verbose >actual &&
+	git worktree prune --verbose 2>actual &&
 	test_i18ngrep "duplicate entry" actual &&
 	test -d .git/worktrees/w1 &&
 	! test -d .git/worktrees/w2
@@ -114,7 +114,7 @@
 	git -C repo worktree add --detach ../wt &&
 	rm -fr wt &&
 	mv repo wt &&
-	git -C wt worktree prune --verbose >actual &&
+	git -C wt worktree prune --verbose 2>actual &&
 	test_i18ngrep "duplicate entry" actual &&
 	! test -d .git/worktrees/wt
 '
diff --git a/t/t2402-worktree-list.sh b/t/t2402-worktree-list.sh
index 4012bd6..c8a5a0a 100755
--- a/t/t2402-worktree-list.sh
+++ b/t/t2402-worktree-list.sh
@@ -134,7 +134,7 @@
 	git worktree list >out &&
 	grep "/prunable  *[0-9a-f].* prunable$" out &&
 	! grep "/unprunable  *[0-9a-f].* unprunable$" out &&
-	git worktree prune --verbose >out &&
+	git worktree prune --verbose 2>out &&
 	test_i18ngrep "^Removing worktrees/prunable" out &&
 	test_i18ngrep ! "^Removing worktrees/unprunable" out
 '
diff --git a/t/t2404-worktree-config.sh b/t/t2404-worktree-config.sh
index 9536d10..842937b 100755
--- a/t/t2404-worktree-config.sh
+++ b/t/t2404-worktree-config.sh
@@ -2,6 +2,7 @@
 
 test_description="config file in multi worktree"
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t2406-worktree-repair.sh b/t/t2406-worktree-repair.sh
index f737418..5c44453 100755
--- a/t/t2406-worktree-repair.sh
+++ b/t/t2406-worktree-repair.sh
@@ -45,9 +45,8 @@
 	git worktree add --detach corrupt &&
 	git -C corrupt rev-parse --absolute-git-dir >expect &&
 	eval "$butcher" &&
-	git -C "$repairdir" worktree repair >out 2>err &&
-	test_i18ngrep "$problem" out &&
-	test_must_be_empty err &&
+	git -C "$repairdir" worktree repair 2>err &&
+	test_i18ngrep "$problem" err &&
 	git -C corrupt rev-parse --absolute-git-dir >actual &&
 	test_cmp expect actual
 }
@@ -130,10 +129,9 @@
 	sed s,orig/\.git$,moved/.git, .git/worktrees/orig/gitdir >expect &&
 	rm .git/worktrees/orig/gitdir &&
 	mv orig moved &&
-	git worktree repair moved >out 2>err &&
+	git worktree repair moved 2>err &&
 	test_cmp expect .git/worktrees/orig/gitdir &&
-	test_i18ngrep "gitdir unreadable" out &&
-	test_must_be_empty err
+	test_i18ngrep "gitdir unreadable" err
 '
 
 test_expect_success 'repair incorrect gitdir' '
@@ -141,10 +139,9 @@
 	git worktree add --detach orig &&
 	sed s,orig/\.git$,moved/.git, .git/worktrees/orig/gitdir >expect &&
 	mv orig moved &&
-	git worktree repair moved >out 2>err &&
+	git worktree repair moved 2>err &&
 	test_cmp expect .git/worktrees/orig/gitdir &&
-	test_i18ngrep "gitdir incorrect" out &&
-	test_must_be_empty err
+	test_i18ngrep "gitdir incorrect" err
 '
 
 test_expect_success 'repair gitdir (implicit) from linked worktree' '
@@ -152,10 +149,9 @@
 	git worktree add --detach orig &&
 	sed s,orig/\.git$,moved/.git, .git/worktrees/orig/gitdir >expect &&
 	mv orig moved &&
-	git -C moved worktree repair >out 2>err &&
+	git -C moved worktree repair 2>err &&
 	test_cmp expect .git/worktrees/orig/gitdir &&
-	test_i18ngrep "gitdir incorrect" out &&
-	test_must_be_empty err
+	test_i18ngrep "gitdir incorrect" err
 '
 
 test_expect_success 'unable to repair gitdir (implicit) from main worktree' '
@@ -163,9 +159,8 @@
 	git worktree add --detach orig &&
 	cat .git/worktrees/orig/gitdir >expect &&
 	mv orig moved &&
-	git worktree repair >out 2>err &&
+	git worktree repair 2>err &&
 	test_cmp expect .git/worktrees/orig/gitdir &&
-	test_must_be_empty out &&
 	test_must_be_empty err
 '
 
@@ -178,12 +173,11 @@
 	sed s,orig2/\.git$,moved2/.git, .git/worktrees/orig2/gitdir >expect2 &&
 	mv orig1 moved1 &&
 	mv orig2 moved2 &&
-	git worktree repair moved1 moved2 >out 2>err &&
+	git worktree repair moved1 moved2 2>err &&
 	test_cmp expect1 .git/worktrees/orig1/gitdir &&
 	test_cmp expect2 .git/worktrees/orig2/gitdir &&
-	test_i18ngrep "gitdir incorrect:.*orig1/gitdir$" out &&
-	test_i18ngrep "gitdir incorrect:.*orig2/gitdir$" out &&
-	test_must_be_empty err
+	test_i18ngrep "gitdir incorrect:.*orig1/gitdir$" err &&
+	test_i18ngrep "gitdir incorrect:.*orig2/gitdir$" err
 '
 
 test_expect_success 'repair moved main and linked worktrees' '
diff --git a/t/t2501-cwd-empty.sh b/t/t2501-cwd-empty.sh
new file mode 100755
index 0000000..f6d8d7d
--- /dev/null
+++ b/t/t2501-cwd-empty.sh
@@ -0,0 +1,277 @@
+#!/bin/sh
+
+test_description='Test handling of the current working directory becoming empty'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	test_commit init &&
+
+	git branch fd_conflict &&
+
+	mkdir -p foo/bar &&
+	test_commit foo/bar/baz &&
+
+	git revert HEAD &&
+	git tag reverted &&
+
+	git checkout fd_conflict &&
+	mkdir dirORfile &&
+	test_commit dirORfile/foo &&
+
+	git rm -r dirORfile &&
+	echo not-a-directory >dirORfile &&
+	git add dirORfile &&
+	git commit -m dirORfile &&
+
+	git switch -c df_conflict HEAD~1 &&
+	test_commit random_file &&
+
+	git switch -c undo_fd_conflict fd_conflict &&
+	git revert HEAD
+'
+
+test_incidental_dir_removal () {
+	test_when_finished "git reset --hard" &&
+
+	git checkout foo/bar/baz^{commit} &&
+	test_path_is_dir foo/bar &&
+
+	(
+		cd foo &&
+		"$@" &&
+
+		# Make sure foo still exists, and commands needing it work
+		test-tool getcwd &&
+		git status --porcelain
+	) &&
+	test_path_is_missing foo/bar/baz &&
+	test_path_is_missing foo/bar &&
+
+	test_path_is_dir foo
+}
+
+test_required_dir_removal () {
+	git checkout df_conflict^{commit} &&
+	test_when_finished "git clean -fdx" &&
+
+	(
+		cd dirORfile &&
+
+		# Ensure command refuses to run
+		test_must_fail "$@" 2>../error &&
+		grep "Refusing to remove.*current working directory" ../error &&
+
+		# ...and that the index and working tree are left clean
+		git diff --exit-code HEAD &&
+
+		# Ensure that getcwd and git status do not error out (which
+		# they might if the current working directory had been removed)
+		test-tool getcwd &&
+		git status --porcelain
+	) &&
+
+	test_path_is_dir dirORfile
+}
+
+test_expect_success 'checkout does not clean cwd incidentally' '
+	test_incidental_dir_removal git checkout init
+'
+
+test_expect_success 'checkout fails if cwd needs to be removed' '
+	test_required_dir_removal git checkout fd_conflict
+'
+
+test_expect_success 'reset --hard does not clean cwd incidentally' '
+	test_incidental_dir_removal git reset --hard init
+'
+
+test_expect_success 'reset --hard fails if cwd needs to be removed' '
+	test_required_dir_removal git reset --hard fd_conflict
+'
+
+test_expect_success 'merge does not clean cwd incidentally' '
+	test_incidental_dir_removal git merge reverted
+'
+
+# This file uses some simple merges where
+#   Base: 'dirORfile/' exists
+#   Side1: random other file changed
+#   Side2: 'dirORfile/' removed, 'dirORfile' added
+# this should resolve cleanly, but merge-recursive throws merge conflicts
+# because it's dumb.  Add a special test for checking merge-recursive (and
+# merge-ort), then after this just hard require ort for all remaining tests.
+#
+test_expect_success 'merge fails if cwd needs to be removed; recursive friendly' '
+	git checkout foo/bar/baz &&
+	test_when_finished "git clean -fdx" &&
+
+	mkdir dirORfile &&
+	(
+		cd dirORfile &&
+
+		test_must_fail git merge fd_conflict 2>../error
+	) &&
+
+	test_path_is_dir dirORfile &&
+	grep "Refusing to remove the current working directory" error
+'
+
+GIT_TEST_MERGE_ALGORITHM=ort
+
+test_expect_success 'merge fails if cwd needs to be removed' '
+	test_required_dir_removal git merge fd_conflict
+'
+
+test_expect_success 'cherry-pick does not clean cwd incidentally' '
+	test_incidental_dir_removal git cherry-pick reverted
+'
+
+test_expect_success 'cherry-pick fails if cwd needs to be removed' '
+	test_required_dir_removal git cherry-pick fd_conflict
+'
+
+test_expect_success 'rebase does not clean cwd incidentally' '
+	test_incidental_dir_removal git rebase reverted
+'
+
+test_expect_success 'rebase fails if cwd needs to be removed' '
+	test_required_dir_removal git rebase fd_conflict
+'
+
+test_expect_success 'revert does not clean cwd incidentally' '
+	test_incidental_dir_removal git revert HEAD
+'
+
+test_expect_success 'revert fails if cwd needs to be removed' '
+	test_required_dir_removal git revert undo_fd_conflict
+'
+
+test_expect_success 'rm does not clean cwd incidentally' '
+	test_incidental_dir_removal git rm bar/baz.t
+'
+
+test_expect_success 'apply does not remove cwd incidentally' '
+	git diff HEAD HEAD~1 >patch &&
+	test_incidental_dir_removal git apply ../patch
+'
+
+test_incidental_untracked_dir_removal () {
+	test_when_finished "git reset --hard" &&
+
+	git checkout foo/bar/baz^{commit} &&
+	mkdir -p untracked &&
+	mkdir empty
+	>untracked/random &&
+
+	(
+		cd untracked &&
+		"$@" &&
+
+		# Make sure untracked still exists, and commands needing it work
+		test-tool getcwd &&
+		git status --porcelain
+	) &&
+	test_path_is_missing empty &&
+	test_path_is_missing untracked/random &&
+
+	test_path_is_dir untracked
+}
+
+test_expect_success 'clean does not remove cwd incidentally' '
+	test_incidental_untracked_dir_removal \
+		git -C .. clean -fd -e warnings . >warnings &&
+	grep "Refusing to remove current working directory" warnings
+'
+
+test_expect_success 'stash does not remove cwd incidentally' '
+	test_incidental_untracked_dir_removal \
+		git stash --include-untracked
+'
+
+test_expect_success '`rm -rf dir` only removes a subset of dir' '
+	test_when_finished "rm -rf a/" &&
+
+	mkdir -p a/b/c &&
+	>a/b/c/untracked &&
+	>a/b/c/tracked &&
+	git add a/b/c/tracked &&
+
+	(
+		cd a/b &&
+		git rm -rf ../b
+	) &&
+
+	test_path_is_dir a/b &&
+	test_path_is_missing a/b/c/tracked &&
+	test_path_is_file a/b/c/untracked
+'
+
+test_expect_success '`rm -rf dir` even with only tracked files will remove something else' '
+	test_when_finished "rm -rf a/" &&
+
+	mkdir -p a/b/c &&
+	>a/b/c/tracked &&
+	git add a/b/c/tracked &&
+
+	(
+		cd a/b &&
+		git rm -rf ../b
+	) &&
+
+	test_path_is_missing a/b/c/tracked &&
+	test_path_is_missing a/b/c &&
+	test_path_is_dir a/b
+'
+
+test_expect_success 'git version continues working from a deleted dir' '
+	mkdir tmp &&
+	(
+		cd tmp &&
+		rm -rf ../tmp &&
+		git version
+	)
+'
+
+test_submodule_removal () {
+	path_status=$1 &&
+	shift &&
+
+	test_status=
+	test "$path_status" = dir && test_status=test_must_fail
+
+	test_when_finished "git reset --hard HEAD~1" &&
+	test_when_finished "rm -rf .git/modules/my_submodule" &&
+
+	git checkout foo/bar/baz &&
+
+	git init my_submodule &&
+	touch my_submodule/file &&
+	git -C my_submodule add file &&
+	git -C my_submodule commit -m "initial commit" &&
+	git submodule add ./my_submodule &&
+	git commit -m "Add the submodule" &&
+
+	(
+		cd my_submodule &&
+		$test_status "$@"
+	) &&
+
+	test_path_is_${path_status} my_submodule
+}
+
+test_expect_success 'rm -r with -C leaves submodule if cwd inside' '
+	test_submodule_removal dir git -C .. rm -r my_submodule/
+'
+
+test_expect_success 'rm -r leaves submodule if cwd inside' '
+	test_submodule_removal dir \
+		git --git-dir=../.git --work-tree=.. rm -r ../my_submodule/
+'
+
+test_expect_success 'rm -rf removes submodule even if cwd inside' '
+	test_submodule_removal missing \
+		git --git-dir=../.git --work-tree=.. rm -rf ../my_submodule/
+'
+
+test_done
diff --git a/t/t3005-ls-files-relative.sh b/t/t3005-ls-files-relative.sh
index 6ba8b58..fbfa210 100755
--- a/t/t3005-ls-files-relative.sh
+++ b/t/t3005-ls-files-relative.sh
@@ -39,10 +39,7 @@
 test_expect_success 'ls-files -c' '
 	(
 		cd top/sub &&
-		for f in ../y*
-		do
-			echo "error: pathspec $SQ$f$SQ did not match any file(s) known to git"
-		done >expect.err &&
+		printf "error: pathspec $SQ%s$SQ did not match any file(s) known to git\n" ../y* >expect.err &&
 		echo "Did you forget to ${SQ}git add${SQ}?" >>expect.err &&
 		ls ../x* >expect.out &&
 		test_must_fail git ls-files -c --error-unmatch ../[xy]* >actual.out 2>actual.err &&
@@ -54,10 +51,7 @@
 test_expect_success 'ls-files -o' '
 	(
 		cd top/sub &&
-		for f in ../x*
-		do
-			echo "error: pathspec $SQ$f$SQ did not match any file(s) known to git"
-		done >expect.err &&
+		printf "error: pathspec $SQ%s$SQ did not match any file(s) known to git\n" ../x* >expect.err &&
 		echo "Did you forget to ${SQ}git add${SQ}?" >>expect.err &&
 		ls ../y* >expect.out &&
 		test_must_fail git ls-files -o --error-unmatch ../[xy]* >actual.out 2>actual.err &&
diff --git a/t/t3040-subprojects-basic.sh b/t/t3040-subprojects-basic.sh
index 6abdcbb..bd65dfc 100755
--- a/t/t3040-subprojects-basic.sh
+++ b/t/t3040-subprojects-basic.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='Basic subproject functionality'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup: create superproject' '
diff --git a/t/t3070-wildmatch.sh b/t/t3070-wildmatch.sh
index 72d5b01..f953996 100755
--- a/t/t3070-wildmatch.sh
+++ b/t/t3070-wildmatch.sh
@@ -193,7 +193,7 @@
 		file=$(cat .git/expected_test_file) &&
 		if should_create_test_file "$file"
 		then
-			dirs=${file%/*}
+			dirs=${file%/*} &&
 			if test "$file" != "$dirs"
 			then
 				mkdir -p -- "$dirs" &&
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index e575ffb..1bc3795 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -168,6 +168,13 @@
 	test_must_fail git branch -M bar foo
 '
 
+test_expect_success 'git branch -M foo bar should fail when bar is checked out in worktree' '
+	git branch -f bar &&
+	test_when_finished "git worktree remove wt && git branch -D wt" &&
+	git worktree add wt &&
+	test_must_fail git branch -M bar wt
+'
+
 test_expect_success 'git branch -M baz bam should succeed when baz is checked out' '
 	git checkout -b baz &&
 	git branch bam &&
@@ -731,6 +738,28 @@
 	test_must_fail git branch -m u v
 '
 
+test_expect_success SYMLINKS 'git branch -m with symlinked .git/refs' '
+	test_when_finished "rm -rf subdir" &&
+	git init --bare subdir &&
+
+	rm -rfv subdir/refs subdir/objects subdir/packed-refs &&
+	ln -s ../.git/refs subdir/refs &&
+	ln -s ../.git/objects subdir/objects &&
+	ln -s ../.git/packed-refs subdir/packed-refs &&
+
+	git -C subdir rev-parse --absolute-git-dir >subdir.dir &&
+	git rev-parse --absolute-git-dir >our.dir &&
+	! test_cmp subdir.dir our.dir &&
+
+	git -C subdir log &&
+	git -C subdir branch rename-src &&
+	git rev-parse rename-src >expect &&
+	git -C subdir branch -m rename-src rename-dest &&
+	git rev-parse rename-dest >actual &&
+	test_cmp expect actual &&
+	git branch -D rename-dest
+'
+
 test_expect_success 'test tracking setup via --track' '
 	git config remote.local.url . &&
 	git config remote.local.fetch refs/heads/*:refs/remotes/local/* &&
@@ -866,7 +895,7 @@
 '
 
 test_expect_success '--set-upstream-to fails on a non-ref' '
-	echo "fatal: Cannot setup tracking information; starting point '"'"'HEAD^{}'"'"' is not a branch." >expect &&
+	echo "fatal: cannot set up tracking information; starting point '"'"'HEAD^{}'"'"' is not a branch" >expect &&
 	test_must_fail git branch --set-upstream-to HEAD^{} 2>err &&
 	test_cmp expect err
 '
@@ -950,15 +979,15 @@
 	test_must_fail git branch --set-upstream origin/main
 '
 
-test_expect_success '--set-upstream-to notices an error to set branch as own upstream' '
+test_expect_success '--set-upstream-to notices an error to set branch as own upstream' "
 	git branch --set-upstream-to refs/heads/my13 my13 2>actual &&
 	cat >expect <<-\EOF &&
-	warning: Not setting branch my13 as its own upstream.
+	warning: not setting branch 'my13' as its own upstream
 	EOF
 	test_expect_code 1 git config branch.my13.remote &&
 	test_expect_code 1 git config branch.my13.merge &&
 	test_cmp expect actual
-'
+"
 
 # Keep this test last, as it changes the current branch
 cat >expect <<EOF
@@ -1418,8 +1447,51 @@
 	(
 		cd sort &&
 		git config branch.sort "v:notvalid" &&
-		test_must_fail git branch
+
+		# this works in the "listing" mode, so bad sort key
+		# is a dying offence.
+		test_must_fail git branch &&
+
+		# these do not need to use sorting, and should all
+		# succeed
+		git branch newone main &&
+		git branch -c newone newerone &&
+		git branch -m newone newestone &&
+		git branch -d newerone newestone
 	)
 '
 
+test_expect_success 'tracking info copied with --track=inherit' '
+	git branch --track=inherit foo2 my1 &&
+	test_cmp_config local branch.foo2.remote &&
+	test_cmp_config refs/heads/main branch.foo2.merge
+'
+
+test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
+	test_unconfig branch.autoSetupMerge &&
+	# default config does not copy tracking info
+	git branch foo-no-inherit my1 &&
+	test_cmp_config "" --default "" branch.foo-no-inherit.remote &&
+	test_cmp_config "" --default "" branch.foo-no-inherit.merge &&
+	# with autoSetupMerge=inherit, we copy tracking info from my1
+	test_config branch.autoSetupMerge inherit &&
+	git branch foo3 my1 &&
+	test_cmp_config local branch.foo3.remote &&
+	test_cmp_config refs/heads/main branch.foo3.merge &&
+	# no tracking info to inherit from main
+	git branch main2 main &&
+	test_cmp_config "" --default "" branch.main2.remote &&
+	test_cmp_config "" --default "" branch.main2.merge
+'
+
+test_expect_success '--track overrides branch.autoSetupMerge' '
+	test_config branch.autoSetupMerge inherit &&
+	git branch --track=direct foo4 my1 &&
+	test_cmp_config . branch.foo4.remote &&
+	test_cmp_config refs/heads/my1 branch.foo4.merge &&
+	git branch --no-track foo5 my1 &&
+	test_cmp_config "" --default "" branch.foo5.remote &&
+	test_cmp_config "" --default "" branch.foo5.merge
+'
+
 test_done
diff --git a/t/t3201-branch-contains.sh b/t/t3201-branch-contains.sh
index 349a810..800fc33 100755
--- a/t/t3201-branch-contains.sh
+++ b/t/t3201-branch-contains.sh
@@ -2,9 +2,6 @@
 
 test_description='branch --contains <commit>, --no-contains <commit> --merged, and --no-merged'
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t3202-show-branch.sh b/t/t3202-show-branch.sh
index ad9902a..7a1be73 100755
--- a/t/t3202-show-branch.sh
+++ b/t/t3202-show-branch.sh
@@ -4,12 +4,15 @@
 
 . ./test-lib.sh
 
+# arbitrary reference time: 2009-08-30 19:20:00
+GIT_TEST_DATE_NOW=1251660000; export GIT_TEST_DATE_NOW
+
 test_expect_success 'setup' '
 	test_commit initial &&
 	for i in $(test_seq 1 10)
 	do
 		git checkout -b branch$i initial &&
-		test_commit --no-tag branch$i
+		test_commit --no-tag branch$i || return 1
 	done &&
 	git for-each-ref \
 		--sort=version:refname \
@@ -49,7 +52,7 @@
 test_expect_success 'show-branch with showbranch.default' '
 	for branch in $(cat branches.sorted)
 	do
-		test_config showbranch.default $branch --add
+		test_config showbranch.default $branch --add || return 1
 	done &&
 	git show-branch >actual &&
 	test_cmp expect actual
@@ -124,7 +127,7 @@
 	do
 		git rev-parse $branch >expect &&
 		git show-branch --merge-base $branch >actual &&
-		test_cmp expect actual
+		test_cmp expect actual || return 1
 	done
 '
 
@@ -133,7 +136,7 @@
 	do
 		git rev-parse initial >expect &&
 		git show-branch --merge-base initial $branch >actual &&
-		test_cmp expect actual
+		test_cmp expect actual || return 1
 	done
 '
 
@@ -146,4 +149,16 @@
 	test_cmp expect actual
 '
 
+test_expect_success 'show branch --reflog=2' '
+	sed "s/^>	//" >expect <<-\EOF &&
+	>	! [refs/heads/branch10@{0}] (4 years, 5 months ago) commit: branch10
+	>	 ! [refs/heads/branch10@{1}] (4 years, 5 months ago) commit: branch10
+	>	--
+	>	+  [refs/heads/branch10@{0}] branch10
+	>	++ [refs/heads/branch10@{1}] initial
+	EOF
+	git show-branch --reflog=2 >actual &&
+	test_cmp actual expect
+'
+
 test_done
diff --git a/t/t3203-branch-output.sh b/t/t3203-branch-output.sh
index 6e94c6d..d34d77f 100755
--- a/t/t3203-branch-output.sh
+++ b/t/t3203-branch-output.sh
@@ -1,9 +1,6 @@
 #!/bin/sh
 
 test_description='git branch display tests'
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-terminal.sh
 
diff --git a/t/t3205-branch-color.sh b/t/t3205-branch-color.sh
index 6a521c1..0b61da9 100755
--- a/t/t3205-branch-color.sh
+++ b/t/t3205-branch-color.sh
@@ -1,9 +1,6 @@
 #!/bin/sh
 
 test_description='basic branch output coloring'
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
diff --git a/t/t3302-notes-index-expensive.sh b/t/t3302-notes-index-expensive.sh
index ef8b639..bc9d8ee 100755
--- a/t/t3302-notes-index-expensive.sh
+++ b/t/t3302-notes-index-expensive.sh
@@ -8,6 +8,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 create_repo () {
diff --git a/t/t3303-notes-subtrees.sh b/t/t3303-notes-subtrees.sh
index d47ce00..7e0a896 100755
--- a/t/t3303-notes-subtrees.sh
+++ b/t/t3303-notes-subtrees.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 number_of_commits=100
@@ -30,7 +31,7 @@
 	while [ $i -gt 0 ]; do
 		echo "    commit #$i" &&
 		echo "    note for commit #$i" &&
-		i=$(($i-1));
+		i=$(($i-1)) || return 1
 	done > expect &&
 	test_cmp expect output
 }
@@ -42,7 +43,7 @@
 		while [ $nr -lt $number_of_commits ]; do
 			nr=$(($nr+1)) &&
 			test_tick &&
-			cat <<INPUT_END
+			cat <<INPUT_END || return 1
 commit refs/heads/main
 committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
 data <<COMMIT
@@ -178,7 +179,7 @@
 		echo "    first note for commit #$i" &&
 		echo "    " &&
 		echo "    second note for commit #$i" &&
-		i=$(($i-1));
+		i=$(($i-1)) || return 1
 	done > expect &&
 	test_cmp expect output
 }
diff --git a/t/t3305-notes-fanout.sh b/t/t3305-notes-fanout.sh
index 94c1b02..1f59648 100755
--- a/t/t3305-notes-fanout.sh
+++ b/t/t3305-notes-fanout.sh
@@ -2,6 +2,7 @@
 
 test_description='Test that adding/removing many notes triggers automatic fanout restructuring'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 path_has_fanout() {
@@ -57,7 +58,7 @@
 	do
 		echo "    commit #$i" &&
 		echo "    note #$i" &&
-		i=$(($i - 1));
+		i=$(($i - 1)) || return 1
 	done > expect &&
 	test_cmp expect output
 '
@@ -106,7 +107,7 @@
 	do
 		echo "    commit #$i" &&
 		echo "    note #$i" &&
-		i=$(($i - 1));
+		i=$(($i - 1)) || return 1
 	done > expect &&
 	test_cmp expect output
 '
diff --git a/t/t3320-notes-merge-worktrees.sh b/t/t3320-notes-merge-worktrees.sh
index 6b2d507..bff0aea 100755
--- a/t/t3320-notes-merge-worktrees.sh
+++ b/t/t3320-notes-merge-worktrees.sh
@@ -8,6 +8,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup commit' '
diff --git a/t/t3402-rebase-merge.sh b/t/t3402-rebase-merge.sh
index cfde68f..7e46f4c 100755
--- a/t/t3402-rebase-merge.sh
+++ b/t/t3402-rebase-merge.sh
@@ -68,7 +68,7 @@
 	if test -s difference
 	then
 		cat difference
-		(exit 1)
+		false
 	else
 		echo happy
 	fi
@@ -102,7 +102,7 @@
 	if test -s difference
 	then
 		cat difference
-		(exit 1)
+		false
 	else
 		echo happy
 	fi
@@ -117,7 +117,7 @@
 		echo happy
 	else
 		git show-branch
-		(exit 1)
+		false
 	fi &&
 	f=$(git diff-tree --name-only HEAD^ HEAD) &&
 	g=$(git diff-tree --name-only HEAD^^ HEAD^) &&
@@ -127,7 +127,7 @@
 	*)
 		echo "$f"
 		echo "$g"
-		(exit 1)
+		false
 	esac
 '
 
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 12eb226..a38f2da 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -25,8 +25,6 @@
  where A, B, D and G all touch file1, and one, two, three, four all
  touch file "conflict".
 '
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 . ./test-lib.sh
 
@@ -826,7 +824,7 @@
 	do
 		test ! $(git rev-parse HEAD~$p) = $(git rev-parse original-no-ff-branch~$p) &&
 		git diff HEAD~$p original-no-ff-branch~$p > out &&
-		test_must_be_empty out
+		test_must_be_empty out || return 1
 	done &&
 	test_cmp_rev HEAD~3 original-no-ff-branch~3 &&
 	git diff HEAD~3 original-no-ff-branch~3 > out &&
@@ -1341,7 +1339,7 @@
 		test_seq 5 | sed "s/$double/&&/" >seq &&
 		git add seq &&
 		test_tick &&
-		git commit -m seq-$double
+		git commit -m seq-$double || return 1
 	done &&
 	git tag seq-onto &&
 	git reset --hard HEAD~2 &&
diff --git a/t/t3409-rebase-environ.sh b/t/t3409-rebase-environ.sh
new file mode 100755
index 0000000..83ffb39
--- /dev/null
+++ b/t/t3409-rebase-environ.sh
@@ -0,0 +1,23 @@
+#!/bin/sh
+
+test_description='git rebase interactive environment'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit one &&
+	test_commit two &&
+	test_commit three
+'
+
+test_expect_success 'rebase --exec does not muck with GIT_DIR' '
+	git rebase --exec "printf %s \$GIT_DIR >environ" HEAD~1 &&
+	test_must_be_empty environ
+'
+
+test_expect_success 'rebase --exec does not muck with GIT_WORK_TREE' '
+	git rebase --exec "printf %s \$GIT_WORK_TREE >environ" HEAD~1 &&
+	test_must_be_empty environ
+'
+
+test_done
diff --git a/t/t3417-rebase-whitespace-fix.sh b/t/t3417-rebase-whitespace-fix.sh
index 946e92f..96f2cf2 100755
--- a/t/t3417-rebase-whitespace-fix.sh
+++ b/t/t3417-rebase-whitespace-fix.sh
@@ -115,9 +115,7 @@
 	git config core.whitespace "blank-at-eol" &&
 	cp beginning file &&
 	git commit -m beginning file &&
-	for i in 1 2 3 4 5; do
-		echo $i
-	done >> file &&
+	test_write_lines 1 2 3 4 5 >>file &&
 	git commit -m more file &&
 	git rebase --whitespace=fix HEAD^^ &&
 	test_cmp expect-beginning file
diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
index eb0a3d9..6dabb05 100755
--- a/t/t3422-rebase-incompatible-options.sh
+++ b/t/t3422-rebase-incompatible-options.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='test if rebase detects and aborts on incompatible options'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t3429-rebase-edit-todo.sh b/t/t3429-rebase-edit-todo.sh
index 7024d49..abd66f3 100755
--- a/t/t3429-rebase-edit-todo.sh
+++ b/t/t3429-rebase-edit-todo.sh
@@ -13,10 +13,15 @@
 
 test_expect_success 'rebase exec modifies rebase-todo' '
 	todo=.git/rebase-merge/git-rebase-todo &&
-	git rebase HEAD -x "echo exec touch F >>$todo" &&
+	git rebase HEAD~1 -x "echo exec touch F >>$todo" &&
 	test -e F
 '
 
+test_expect_success 'rebase exec with an empty list does not exec anything' '
+	git rebase HEAD -x "true" 2>output &&
+	! grep "Executing: true" output
+'
+
 test_expect_success 'loose object cache vs re-reading todo list' '
 	GIT_REBASE_TODO=.git/rebase-merge/git-rebase-todo &&
 	export GIT_REBASE_TODO &&
diff --git a/t/t3431-rebase-fork-point.sh b/t/t3431-rebase-fork-point.sh
index 4c98d99..1d0b153 100755
--- a/t/t3431-rebase-fork-point.sh
+++ b/t/t3431-rebase-fork-point.sh
@@ -83,7 +83,7 @@
 
 test_expect_success '--fork-point and --root both given' '
 	test_must_fail git rebase --fork-point --root 2>err &&
-	test_i18ngrep "cannot combine" err
+	test_i18ngrep "cannot be used together" err
 '
 
 test_expect_success 'rebase.forkPoint set to false' '
diff --git a/t/t3501-revert-cherry-pick.sh b/t/t3501-revert-cherry-pick.sh
index 4b5b607..8617efa 100755
--- a/t/t3501-revert-cherry-pick.sh
+++ b/t/t3501-revert-cherry-pick.sh
@@ -19,7 +19,7 @@
 
 	for l in a b c d e f g h i j k l m n o
 	do
-		echo $l$l$l$l$l$l$l$l$l
+		echo $l$l$l$l$l$l$l$l$l || return 1
 	done >oops &&
 
 	test_tick &&
diff --git a/t/t3508-cherry-pick-many-commits.sh b/t/t3508-cherry-pick-many-commits.sh
index e8375d1..2d53ce7 100755
--- a/t/t3508-cherry-pick-many-commits.sh
+++ b/t/t3508-cherry-pick-many-commits.sh
@@ -29,7 +29,7 @@
 		git add file1 &&
 		test_tick &&
 		git commit -m "$val" &&
-		git tag $val
+		git tag $val || return 1
 	done
 '
 
diff --git a/t/t3600-rm.sh b/t/t3600-rm.sh
index bb9ef35..e74a318 100755
--- a/t/t3600-rm.sh
+++ b/t/t3600-rm.sh
@@ -265,7 +265,7 @@
 
 test_expect_success !MINGW 'choking "git rm" should not let it die with cruft (induce and check SIGPIPE)' '
 	choke_git_rm_setup &&
-	OUT=$( ((trap "" PIPE; git rm -n "some-file-*"; echo $? 1>&3) | :) 3>&1 ) &&
+	OUT=$( ((trap "" PIPE && git rm -n "some-file-*"; echo $? 1>&3) | :) 3>&1 ) &&
 	test_match_signal 13 "$OUT" &&
 	test_path_is_missing .git/index.lock
 '
@@ -274,10 +274,7 @@
 	git reset -q --hard &&
 	test_when_finished "rm -f .git/index.lock msg && git reset -q --hard" &&
 	blob=$(echo blob | git hash-object -w --stdin) &&
-	for stage in 1 2 3
-	do
-		echo "100644 $blob $stage	blob"
-	done | git update-index --index-info &&
+	printf "100644 $blob %d\tblob\n" 1 2 3 | git update-index --index-info &&
 	git rm blob >msg 2>&1 &&
 	test_i18ngrep ! "needs merge" msg &&
 	test_must_fail git ls-files -s --error-unmatch blob
diff --git a/t/t3601-rm-pathspec-file.sh b/t/t3601-rm-pathspec-file.sh
index b2a8db6..a2a0c82 100755
--- a/t/t3601-rm-pathspec-file.sh
+++ b/t/t3601-rm-pathspec-file.sh
@@ -67,10 +67,10 @@
 	echo fileA.t >list &&
 
 	test_must_fail git rm --pathspec-from-file=list -- fileA.t 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with pathspec arguments" err &&
+	test_i18ngrep -e ".--pathspec-from-file. and pathspec arguments cannot be used together" err &&
 
 	test_must_fail git rm --pathspec-file-nul 2>err &&
-	test_i18ngrep -e "--pathspec-file-nul requires --pathspec-from-file" err &&
+	test_i18ngrep -e "the option .--pathspec-file-nul. requires .--pathspec-from-file." err &&
 
 	>empty_list &&
 	test_must_fail git rm --pathspec-from-file=empty_list 2>err &&
diff --git a/t/t3700-add.sh b/t/t3700-add.sh
index 283a669..b1f90ba 100755
--- a/t/t3700-add.sh
+++ b/t/t3700-add.sh
@@ -141,9 +141,9 @@
 test_expect_success 'git add with filemode=0, symlinks=0, and unmerged entries' '
 	for s in 1 2 3
 	do
-		echo $s > stage$s
-		echo "100755 $(git hash-object -w stage$s) $s	file"
-		echo "120000 $(printf $s | git hash-object -w -t blob --stdin) $s	symlink"
+		echo $s > stage$s &&
+		echo "100755 $(git hash-object -w stage$s) $s	file" &&
+		echo "120000 $(printf $s | git hash-object -w -t blob --stdin) $s	symlink" || return 1
 	done | git update-index --index-info &&
 	git config core.filemode 0 &&
 	git config core.symlinks 0 &&
@@ -177,7 +177,7 @@
 	git read-tree HEAD &&
 	case "$(git diff-index HEAD -- foo)" in
 	:100644" "*"M	foo") echo pass;;
-	*) echo fail; (exit 1);;
+	*) echo fail; false;;
 	esac &&
 	git add --refresh -- foo &&
 	test -z "$(git diff-index HEAD -- foo)"
diff --git a/t/t3702-add-edit.sh b/t/t3702-add-edit.sh
index 6c67664..a1801a8 100755
--- a/t/t3702-add-edit.sh
+++ b/t/t3702-add-edit.sh
@@ -4,6 +4,8 @@
 #
 
 test_description='add -e basic tests'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 
diff --git a/t/t3703-add-magic-pathspec.sh b/t/t3703-add-magic-pathspec.sh
index 3ef525a..d840710 100755
--- a/t/t3703-add-magic-pathspec.sh
+++ b/t/t3703-add-magic-pathspec.sh
@@ -2,6 +2,7 @@
 
 test_description='magic pathspec tests using git-add'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t3704-add-pathspec-file.sh b/t/t3704-add-pathspec-file.sh
index 9e35c1f..4e6b517 100755
--- a/t/t3704-add-pathspec-file.sh
+++ b/t/t3704-add-pathspec-file.sh
@@ -2,6 +2,7 @@
 
 test_description='add --pathspec-from-file'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_tick
@@ -137,19 +138,19 @@
 	>empty_list &&
 
 	test_must_fail git add --pathspec-from-file=list --interactive 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --interactive/--patch" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--interactive/--patch. cannot be used together" err &&
 
 	test_must_fail git add --pathspec-from-file=list --patch 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --interactive/--patch" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--interactive/--patch. cannot be used together" err &&
 
 	test_must_fail git add --pathspec-from-file=list --edit 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --edit" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--edit. cannot be used together" err &&
 
 	test_must_fail git add --pathspec-from-file=list -- fileA.t 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with pathspec arguments" err &&
+	test_i18ngrep -e ".--pathspec-from-file. and pathspec arguments cannot be used together" err &&
 
 	test_must_fail git add --pathspec-file-nul 2>err &&
-	test_i18ngrep -e "--pathspec-file-nul requires --pathspec-from-file" err &&
+	test_i18ngrep -e "the option .--pathspec-file-nul. requires .--pathspec-from-file." err &&
 
 	# This case succeeds, but still prints to stderr
 	git add --pathspec-from-file=empty_list 2>err &&
diff --git a/t/t3705-add-sparse-checkout.sh b/t/t3705-add-sparse-checkout.sh
index f3143c9..81f3384 100755
--- a/t/t3705-add-sparse-checkout.sh
+++ b/t/t3705-add-sparse-checkout.sh
@@ -181,13 +181,13 @@
 	# Avoid munging CRLFs to avoid an error message
 	git -c core.autocrlf=input add --sparse sparse_entry 2>stderr &&
 	test_must_be_empty stderr &&
-	test-tool read-cache --table >actual &&
-	grep "^100644 blob.*sparse_entry\$" actual &&
+	git ls-files --stage >actual &&
+	grep "^100644 .*sparse_entry\$" actual &&
 
 	git add --sparse --chmod=+x sparse_entry 2>stderr &&
 	test_must_be_empty stderr &&
-	test-tool read-cache --table >actual &&
-	grep "^100755 blob.*sparse_entry\$" actual &&
+	git ls-files --stage >actual &&
+	grep "^100755 .*sparse_entry\$" actual &&
 
 	git reset &&
 
diff --git a/t/t3800-mktag.sh b/t/t3800-mktag.sh
index 0544d58..e3cf0ff 100755
--- a/t/t3800-mktag.sh
+++ b/t/t3800-mktag.sh
@@ -72,7 +72,8 @@
 
 		# Manually create the broken, we cannot do it with
 		# update-ref
-		echo "$bad_tag" >"bad-tag/$tag_ref" &&
+		test-tool -C bad-tag ref-store main delete-refs 0 msg "$tag_ref" &&
+		test-tool -C bad-tag ref-store main update-ref msg "$tag_ref" $bad_tag $ZERO_OID REF_SKIP_OID_VERIFICATION &&
 
 		# Unlike fsck-ing unreachable content above, this
 		# will always fail.
@@ -83,7 +84,8 @@
 		# Make sure the earlier test created it for us
 		git rev-parse "$bad_tag" &&
 
-		echo "$bad_tag" >"bad-tag/$tag_ref" &&
+		test-tool -C bad-tag ref-store main delete-refs 0 msg "$tag_ref" &&
+		test-tool -C bad-tag ref-store main update-ref msg "$tag_ref" $bad_tag $ZERO_OID REF_SKIP_OID_VERIFICATION &&
 
 		printf "%s tag\t%s\n" "$bad_tag" "$tag_ref" >expected &&
 		git -C bad-tag for-each-ref "$tag_ref" >actual &&
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index f0a82be..686747e 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -10,6 +10,25 @@
 
 . ./test-lib.sh
 
+test_expect_success 'usage on cmd and subcommand invalid option' '
+	test_expect_code 129 git stash --invalid-option 2>usage &&
+	grep "or: git stash" usage &&
+
+	test_expect_code 129 git stash push --invalid-option 2>usage &&
+	! grep "or: git stash" usage
+'
+
+test_expect_success 'usage on main command -h emits a summary of subcommands' '
+	test_expect_code 129 git stash -h >usage &&
+	grep -F "usage: git stash list" usage &&
+	grep -F "or: git stash show" usage
+'
+
+test_expect_failure 'usage for subcommands should emit subcommand usage' '
+	test_expect_code 129 git stash push -h >usage &&
+	grep -F "usage: git stash [push" usage
+'
+
 diff_cmp () {
 	for i in "$1" "$2"
 	do
@@ -288,6 +307,17 @@
 	test bar,bar2 = $(cat file),$(cat file2)
 '
 
+test_expect_success 'stash --staged' '
+	echo bar3 >file &&
+	echo bar4 >file2 &&
+	git add file2 &&
+	git stash --staged &&
+	test bar3,bar2 = $(cat file),$(cat file2) &&
+	git reset --hard &&
+	git stash pop &&
+	test bar,bar4 = $(cat file),$(cat file2)
+'
+
 test_expect_success 'dont assume push with non-option args' '
 	test_must_fail git stash -q drop 2>err &&
 	test_i18ngrep -e "subcommand wasn'\''t specified; '\''push'\'' can'\''t be assumed due to unexpected token '\''drop'\''" err
@@ -1365,4 +1395,28 @@
 	)
 '
 
+test_expect_success 'restore untracked files even when we hit conflicts' '
+	git init restore_untracked_after_conflict &&
+	(
+		cd restore_untracked_after_conflict &&
+
+		echo hi >a &&
+		echo there >b &&
+		git add . &&
+		git commit -m first &&
+		echo hello >a &&
+		echo something >c &&
+
+		git stash push --include-untracked &&
+
+		echo conflict >a &&
+		git add a &&
+		git commit -m second &&
+
+		test_must_fail git stash pop &&
+
+		test_path_is_file c
+	)
+'
+
 test_done
diff --git a/t/t3908-stash-in-worktree.sh b/t/t3908-stash-in-worktree.sh
index 2b2b366..347a89b 100755
--- a/t/t3908-stash-in-worktree.sh
+++ b/t/t3908-stash-in-worktree.sh
@@ -5,6 +5,7 @@
 
 test_description='Test git stash in a worktree'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t3909-stash-pathspec-file.sh b/t/t3909-stash-pathspec-file.sh
index 55e050c..dead9f1 100755
--- a/t/t3909-stash-pathspec-file.sh
+++ b/t/t3909-stash-pathspec-file.sh
@@ -88,13 +88,13 @@
 	echo fileA.t >list &&
 
 	test_must_fail git stash push --pathspec-from-file=list --patch 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --patch" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--patch. cannot be used together" err &&
 
 	test_must_fail git stash push --pathspec-from-file=list -- fileA.t 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with pathspec arguments" err &&
+	test_i18ngrep -e ".--pathspec-from-file. and pathspec arguments cannot be used together" err &&
 
 	test_must_fail git stash push --pathspec-file-nul 2>err &&
-	test_i18ngrep -e "--pathspec-file-nul requires --pathspec-from-file" err
+	test_i18ngrep -e "the option .--pathspec-file-nul. requires .--pathspec-from-file." err
 '
 
 test_done
diff --git a/t/t3920-crlf-messages.sh b/t/t3920-crlf-messages.sh
index a8ad546..0276edb 100755
--- a/t/t3920-crlf-messages.sh
+++ b/t/t3920-crlf-messages.sh
@@ -70,7 +70,7 @@
 			for ref in ${LIB_CRLF_BRANCHES}
 			do
 				cat .crlf-${file}-\"\${ref}\".txt >>expect &&
-				printf \"\n\" >>expect
+				printf \"\n\" >>expect || return 1
 			done &&
 			git $command_and_args --format=\"%${atom}\" >actual &&
 			test_cmp expect actual
@@ -90,7 +90,7 @@
 	do
 		printf "  " >>expect &&
 		cat .crlf-subject-${branch}.txt >>expect &&
-		printf "\n" >>expect
+		printf "\n" >>expect || return 1
 	done &&
 	git branch -v >tmp &&
 	# Remove first two columns, and the line for the currently checked out branch
diff --git a/t/t4000-diff-format.sh b/t/t4000-diff-format.sh
index cce3349..bfcaae3 100755
--- a/t/t4000-diff-format.sh
+++ b/t/t4000-diff-format.sh
@@ -6,6 +6,8 @@
 test_description='Test built-in diff output engine.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh
 
diff --git a/t/t4001-diff-rename.sh b/t/t4001-diff-rename.sh
index 68f2ebc..3dc9047 100755
--- a/t/t4001-diff-rename.sh
+++ b/t/t4001-diff-rename.sh
@@ -174,7 +174,7 @@
 	do
 		for j in 0 1 2 3 4 5 6 7 8 9;
 		do
-			echo "$i$j" >"path$i$j"
+			echo "$i$j" >"path$i$j" || return 1
 		done
 	done &&
 	git add "path??" &&
diff --git a/t/t4003-diff-rename-1.sh b/t/t4003-diff-rename-1.sh
index f4485a8..181e968 100755
--- a/t/t4003-diff-rename-1.sh
+++ b/t/t4003-diff-rename-1.sh
@@ -6,6 +6,8 @@
 test_description='More rename detection
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh ;# test-lib chdir's into trash
 
diff --git a/t/t4004-diff-rename-symlink.sh b/t/t4004-diff-rename-symlink.sh
index 3d495e3..8def4d4 100755
--- a/t/t4004-diff-rename-symlink.sh
+++ b/t/t4004-diff-rename-symlink.sh
@@ -9,6 +9,8 @@
 copy of symbolic links, but should not produce rename/copy followed
 by an edit for them.
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh
 
diff --git a/t/t4005-diff-rename-2.sh b/t/t4005-diff-rename-2.sh
index 6f1b323..5c756dc 100755
--- a/t/t4005-diff-rename-2.sh
+++ b/t/t4005-diff-rename-2.sh
@@ -5,6 +5,8 @@
 
 test_description='Same rename detection as t4003 but testing diff-raw.'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh ;# test-lib chdir's into trash
 
diff --git a/t/t4006-diff-mode.sh b/t/t4006-diff-mode.sh
index 6cdee2a..dbd4c0d 100755
--- a/t/t4006-diff-mode.sh
+++ b/t/t4006-diff-mode.sh
@@ -6,6 +6,8 @@
 test_description='Test mode change diffs.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 sed_script='s/\(:100644 100755\) \('"$OID_REGEX"'\) \2 /\1 X X /'
diff --git a/t/t4007-rename-3.sh b/t/t4007-rename-3.sh
index c634653..b86165c 100755
--- a/t/t4007-rename-3.sh
+++ b/t/t4007-rename-3.sh
@@ -6,6 +6,8 @@
 test_description='Rename interaction with pathspec.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh ;# test-lib chdir's into trash
 
diff --git a/t/t4009-diff-rename-4.sh b/t/t4009-diff-rename-4.sh
index 59b7f44..3480781 100755
--- a/t/t4009-diff-rename-4.sh
+++ b/t/t4009-diff-rename-4.sh
@@ -6,6 +6,8 @@
 test_description='Same rename detection as t4003 but testing diff-raw -z.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh ;# test-lib chdir's into trash
 
diff --git a/t/t4010-diff-pathspec.sh b/t/t4010-diff-pathspec.sh
index 1bbced7..9d9650e 100755
--- a/t/t4010-diff-pathspec.sh
+++ b/t/t4010-diff-pathspec.sh
@@ -9,6 +9,8 @@
         file0
         path1/file1
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh ;# test-lib chdir's into trash
 
diff --git a/t/t4011-diff-symlink.sh b/t/t4011-diff-symlink.sh
index 5a25c25..d7a5f7a 100755
--- a/t/t4011-diff-symlink.sh
+++ b/t/t4011-diff-symlink.sh
@@ -6,6 +6,8 @@
 test_description='Test diff of symlinks.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh
 
diff --git a/t/t4012-diff-binary.sh b/t/t4012-diff-binary.sh
index 33ff588..c509143 100755
--- a/t/t4012-diff-binary.sh
+++ b/t/t4012-diff-binary.sh
@@ -6,6 +6,7 @@
 test_description='Binary diff and apply
 '
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 cat >expect.binary-numstat <<\EOF
@@ -122,7 +123,7 @@
 	i=0 &&
 	while test $i -lt 10000; do
 		echo $i &&
-		i=$(($i + 1))
+		i=$(($i + 1)) || return 1
 	done >textfile &&
 	git add textfile &&
 	git diff --cached --stat binfile textfile >output &&
diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index 28683d0..750aee1 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -19,8 +19,8 @@
 
 	mkdir dir &&
 	mkdir dir2 &&
-	for i in 1 2 3; do echo $i; done >file0 &&
-	for i in A B; do echo $i; done >dir/sub &&
+	test_write_lines 1 2 3 >file0 &&
+	test_write_lines A B >dir/sub &&
 	cat file0 >file2 &&
 	git add file0 file2 dir/sub &&
 	git commit -m Initial &&
@@ -32,8 +32,8 @@
 	GIT_COMMITTER_DATE="2006-06-26 00:01:00 +0000" &&
 	export GIT_AUTHOR_DATE GIT_COMMITTER_DATE &&
 
-	for i in 4 5 6; do echo $i; done >>file0 &&
-	for i in C D; do echo $i; done >>dir/sub &&
+	test_write_lines 4 5 6 >>file0 &&
+	test_write_lines C D >>dir/sub &&
 	rm -f file2 &&
 	git update-index --remove file0 file2 dir/sub &&
 	git commit -m "Second${LF}${LF}This is the second commit." &&
@@ -42,9 +42,9 @@
 	GIT_COMMITTER_DATE="2006-06-26 00:02:00 +0000" &&
 	export GIT_AUTHOR_DATE GIT_COMMITTER_DATE &&
 
-	for i in A B C; do echo $i; done >file1 &&
+	test_write_lines A B C >file1 &&
 	git add file1 &&
-	for i in E F; do echo $i; done >>dir/sub &&
+	test_write_lines E F >>dir/sub &&
 	git update-index dir/sub &&
 	git commit -m Third &&
 
@@ -53,8 +53,8 @@
 	export GIT_AUTHOR_DATE GIT_COMMITTER_DATE &&
 
 	git checkout side &&
-	for i in A B C; do echo $i; done >>file0 &&
-	for i in 1 2; do echo $i; done >>dir/sub &&
+	test_write_lines A B C >>file0 &&
+	test_write_lines 1 2 >>dir/sub &&
 	cat dir/sub >file3 &&
 	git add file3 &&
 	git update-index file0 dir/sub &&
@@ -71,8 +71,8 @@
 	GIT_COMMITTER_DATE="2006-06-26 00:05:00 +0000" &&
 	export GIT_AUTHOR_DATE GIT_COMMITTER_DATE &&
 
-	for i in A B C; do echo $i; done >>file0 &&
-	for i in 1 2; do echo $i; done >>dir/sub &&
+	test_write_lines A B C >>file0 &&
+	test_write_lines 1 2 >>dir/sub &&
 	git update-index file0 dir/sub &&
 
 	mkdir dir3 &&
@@ -86,7 +86,7 @@
 	GIT_COMMITTER_DATE="2006-06-26 00:06:00 +0000" &&
 	export GIT_AUTHOR_DATE GIT_COMMITTER_DATE &&
 	git checkout -b rearrange initial &&
-	for i in B A; do echo $i; done >dir/sub &&
+	test_write_lines B A >dir/sub &&
 	git add dir/sub &&
 	git commit -m "Rearranged lines in dir/sub" &&
 	git checkout master &&
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 712d4b5..7dc5a5c 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -12,25 +12,25 @@
 . "$TEST_DIRECTORY"/lib-terminal.sh
 
 test_expect_success setup '
-	for i in 1 2 3 4 5 6 7 8 9 10; do echo "$i"; done >file &&
+	test_write_lines 1 2 3 4 5 6 7 8 9 10 >file &&
 	cat file >elif &&
 	git add file elif &&
 	test_tick &&
 	git commit -m Initial &&
 	git checkout -b side &&
 
-	for i in 1 2 5 6 A B C 7 8 9 10; do echo "$i"; done >file &&
+	test_write_lines 1 2 5 6 A B C 7 8 9 10 >file &&
 	test_chmod +x elif &&
 	test_tick &&
 	git commit -m "Side changes #1" &&
 
-	for i in D E F; do echo "$i"; done >>file &&
+	test_write_lines D E F >>file &&
 	git update-index file &&
 	test_tick &&
 	git commit -m "Side changes #2" &&
 	git tag C2 &&
 
-	for i in 5 6 1 2 3 A 4 B C 7 8 9 10 D E F; do echo "$i"; done >file &&
+	test_write_lines 5 6 1 2 3 A 4 B C 7 8 9 10 D E F >file &&
 	git update-index file &&
 	test_tick &&
 	git commit -m "Side changes #3 with \\n backslash-n in it." &&
@@ -43,18 +43,18 @@
 
 	git checkout side &&
 	git checkout -b patchid &&
-	for i in 5 6 1 2 3 A 4 B C 7 8 9 10 D E F; do echo "$i"; done >file2 &&
-	for i in 1 2 3 A 4 B C 7 8 9 10 D E F 5 6; do echo "$i"; done >file3 &&
-	for i in 8 9 10; do echo "$i"; done >file &&
+	test_write_lines 5 6 1 2 3 A 4 B C 7 8 9 10 D E F >file2 &&
+	test_write_lines 1 2 3 A 4 B C 7 8 9 10 D E F 5 6 >file3 &&
+	test_write_lines 8 9 10 >file &&
 	git add file file2 file3 &&
 	test_tick &&
 	git commit -m "patchid 1" &&
-	for i in 4 A B 7 8 9 10; do echo "$i"; done >file2 &&
-	for i in 8 9 10 5 6; do echo "$i"; done >file3 &&
+	test_write_lines 4 A B 7 8 9 10 >file2 &&
+	test_write_lines 8 9 10 5 6 >file3 &&
 	git add file2 file3 &&
 	test_tick &&
 	git commit -m "patchid 2" &&
-	for i in 10 5 6; do echo "$i"; done >file &&
+	test_write_lines 10 5 6 >file &&
 	git add file &&
 	test_tick &&
 	git commit -m "patchid 3" &&
@@ -325,7 +325,7 @@
 		max=$(
 			for patch in 000[1-9]-*.patch
 			do
-				echo "$patch" | wc -c
+				echo "$patch" | wc -c || exit 1
 			done |
 			sort -nr |
 			head -n 1
@@ -343,7 +343,7 @@
 		max=$(
 			for patch in 000[1-9]-*.patch
 			do
-				echo "$patch" | wc -c
+				echo "$patch" | wc -c || exit 1
 			done |
 			sort -nr |
 			head -n 1
@@ -361,7 +361,7 @@
 		max=$(
 			for patch in patches/000[1-9]-*.patch
 			do
-				echo "${patch#patches/}" | wc -c
+				echo "${patch#patches/}" | wc -c || exit 1
 			done |
 			sort -nr |
 			head -n 1
@@ -653,7 +653,7 @@
 	git checkout side &&
 	before=$(git hash-object file) &&
 	before=$(git rev-parse --short $before) &&
-	for i in 5 6 1 2 3 A 4 B C 7 8 9 10 D E F; do echo "$i"; done >>file &&
+	test_write_lines 5 6 1 2 3 A 4 B C 7 8 9 10 D E F >>file &&
 	after=$(git hash-object file) &&
 	after=$(git rev-parse --short $after) &&
 	git update-index file &&
@@ -1086,7 +1086,7 @@
 test_expect_success 'format-patch handles multi-line subjects' '
 	rm -rf patches/ &&
 	echo content >>file &&
-	for i in one two three; do echo $i; done >msg &&
+	test_write_lines one two three >msg &&
 	git add file &&
 	git commit -F msg &&
 	git format-patch -o patches -1 &&
@@ -1098,7 +1098,7 @@
 test_expect_success 'format-patch handles multi-line encoded subjects' '
 	rm -rf patches/ &&
 	echo content >>file &&
-	for i in en två tre; do echo $i; done >msg &&
+	test_write_lines en två tre >msg &&
 	git add file &&
 	git commit -F msg &&
 	git format-patch -o patches -1 &&
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 2c13b62..9babf13 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -843,7 +843,7 @@
 
 test_expect_success 'whitespace-only changes reported across renames (diffstat)' '
 	git reset --hard &&
-	for i in 1 2 3 4 5 6 7 8 9; do echo "$i$i$i$i$i$i"; done >x &&
+	for i in 1 2 3 4 5 6 7 8 9; do echo "$i$i$i$i$i$i" || return 1; done >x &&
 	git add x &&
 	git commit -m "base" &&
 	sed -e "5s/^/ /" x >z &&
@@ -859,7 +859,7 @@
 
 test_expect_success 'whitespace-only changes reported across renames' '
 	git reset --hard HEAD~1 &&
-	for i in 1 2 3 4 5 6 7 8 9; do echo "$i$i$i$i$i$i"; done >x &&
+	for i in 1 2 3 4 5 6 7 8 9; do echo "$i$i$i$i$i$i" || return 1; done >x &&
 	git add x &&
 	hash_x=$(git hash-object x) &&
 	before=$(git rev-parse --short "$hash_x") &&
@@ -1442,6 +1442,143 @@
 	test_cmp expected actual
 '
 
+test_expect_success 'zebra alternate color is only used when necessary' '
+	cat >old.txt <<-\EOF &&
+	line 1A should be marked as oldMoved newMovedAlternate
+	line 1B should be marked as oldMoved newMovedAlternate
+	unchanged
+	line 2A should be marked as oldMoved newMovedAlternate
+	line 2B should be marked as oldMoved newMovedAlternate
+	line 3A should be marked as oldMovedAlternate newMoved
+	line 3B should be marked as oldMovedAlternate newMoved
+	unchanged
+	line 4A should be marked as oldMoved newMovedAlternate
+	line 4B should be marked as oldMoved newMovedAlternate
+	line 5A should be marked as oldMovedAlternate newMoved
+	line 5B should be marked as oldMovedAlternate newMoved
+	line 6A should be marked as oldMoved newMoved
+	line 6B should be marked as oldMoved newMoved
+	EOF
+	cat >new.txt <<-\EOF &&
+	  line 1A should be marked as oldMoved newMovedAlternate
+	  line 1B should be marked as oldMoved newMovedAlternate
+	unchanged
+	  line 3A should be marked as oldMovedAlternate newMoved
+	  line 3B should be marked as oldMovedAlternate newMoved
+	  line 2A should be marked as oldMoved newMovedAlternate
+	  line 2B should be marked as oldMoved newMovedAlternate
+	unchanged
+	  line 6A should be marked as oldMoved newMoved
+	  line 6B should be marked as oldMoved newMoved
+	    line 4A should be marked as oldMoved newMovedAlternate
+	    line 4B should be marked as oldMoved newMovedAlternate
+	  line 5A should be marked as oldMovedAlternate newMoved
+	  line 5B should be marked as oldMovedAlternate newMoved
+	EOF
+	test_expect_code 1 git diff --no-index --color --color-moved=zebra \
+		 --color-moved-ws=allow-indentation-change \
+		 old.txt new.txt >output &&
+	grep -v index output | test_decode_color >actual &&
+	cat >expected <<-\EOF &&
+	<BOLD>diff --git a/old.txt b/new.txt<RESET>
+	<BOLD>--- a/old.txt<RESET>
+	<BOLD>+++ b/new.txt<RESET>
+	<CYAN>@@ -1,14 +1,14 @@<RESET>
+	<BOLD;MAGENTA>-line 1A should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;MAGENTA>-line 1B should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>  line 1A should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>  line 1B should be marked as oldMoved newMovedAlternate<RESET>
+	 unchanged<RESET>
+	<BOLD;MAGENTA>-line 2A should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;MAGENTA>-line 2B should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;BLUE>-line 3A should be marked as oldMovedAlternate newMoved<RESET>
+	<BOLD;BLUE>-line 3B should be marked as oldMovedAlternate newMoved<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>  line 3A should be marked as oldMovedAlternate newMoved<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>  line 3B should be marked as oldMovedAlternate newMoved<RESET>
+	<BOLD;YELLOW>+<RESET><BOLD;YELLOW>  line 2A should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;YELLOW>+<RESET><BOLD;YELLOW>  line 2B should be marked as oldMoved newMovedAlternate<RESET>
+	 unchanged<RESET>
+	<BOLD;MAGENTA>-line 4A should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;MAGENTA>-line 4B should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;BLUE>-line 5A should be marked as oldMovedAlternate newMoved<RESET>
+	<BOLD;BLUE>-line 5B should be marked as oldMovedAlternate newMoved<RESET>
+	<BOLD;MAGENTA>-line 6A should be marked as oldMoved newMoved<RESET>
+	<BOLD;MAGENTA>-line 6B should be marked as oldMoved newMoved<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>  line 6A should be marked as oldMoved newMoved<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>  line 6B should be marked as oldMoved newMoved<RESET>
+	<BOLD;YELLOW>+<RESET><BOLD;YELLOW>    line 4A should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;YELLOW>+<RESET><BOLD;YELLOW>    line 4B should be marked as oldMoved newMovedAlternate<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>  line 5A should be marked as oldMovedAlternate newMoved<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>  line 5B should be marked as oldMovedAlternate newMoved<RESET>
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'short lines of opposite sign do not get marked as moved' '
+	cat >old.txt <<-\EOF &&
+	this line should be marked as moved
+	unchanged
+	unchanged
+	unchanged
+	unchanged
+	too short
+	this line should be marked as oldMoved newMoved
+	this line should be marked as oldMovedAlternate newMoved
+	unchanged 1
+	unchanged 2
+	unchanged 3
+	unchanged 4
+	this line should be marked as oldMoved newMoved/newMovedAlternate
+	EOF
+	cat >new.txt <<-\EOF &&
+	too short
+	unchanged
+	unchanged
+	this line should be marked as moved
+	too short
+	unchanged
+	unchanged
+	this line should be marked as oldMoved newMoved/newMovedAlternate
+	unchanged 1
+	unchanged 2
+	this line should be marked as oldMovedAlternate newMoved
+	this line should be marked as oldMoved newMoved/newMovedAlternate
+	unchanged 3
+	this line should be marked as oldMoved newMoved
+	unchanged 4
+	EOF
+	test_expect_code 1 git diff --no-index --color --color-moved=zebra \
+		old.txt new.txt >output && cat output &&
+	grep -v index output | test_decode_color >actual &&
+	cat >expect <<-\EOF &&
+	<BOLD>diff --git a/old.txt b/new.txt<RESET>
+	<BOLD>--- a/old.txt<RESET>
+	<BOLD>+++ b/new.txt<RESET>
+	<CYAN>@@ -1,13 +1,15 @@<RESET>
+	<BOLD;MAGENTA>-this line should be marked as moved<RESET>
+	<GREEN>+<RESET><GREEN>too short<RESET>
+	 unchanged<RESET>
+	 unchanged<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>this line should be marked as moved<RESET>
+	<GREEN>+<RESET><GREEN>too short<RESET>
+	 unchanged<RESET>
+	 unchanged<RESET>
+	<RED>-too short<RESET>
+	<BOLD;MAGENTA>-this line should be marked as oldMoved newMoved<RESET>
+	<BOLD;BLUE>-this line should be marked as oldMovedAlternate newMoved<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>this line should be marked as oldMoved newMoved/newMovedAlternate<RESET>
+	 unchanged 1<RESET>
+	 unchanged 2<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>this line should be marked as oldMovedAlternate newMoved<RESET>
+	<BOLD;YELLOW>+<RESET><BOLD;YELLOW>this line should be marked as oldMoved newMoved/newMovedAlternate<RESET>
+	 unchanged 3<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>this line should be marked as oldMoved newMoved<RESET>
+	 unchanged 4<RESET>
+	<BOLD;MAGENTA>-this line should be marked as oldMoved newMoved/newMovedAlternate<RESET>
+	EOF
+	test_cmp expect actual
+'
+
 test_expect_success 'cmd option assumes configured colored-moved' '
 	test_config color.diff.oldMoved "magenta" &&
 	test_config color.diff.newMoved "cyan" &&
@@ -1833,6 +1970,52 @@
 	test_cmp expected actual
 '
 
+test_expect_success '--color-moved rewinds for MIN_ALNUM_COUNT' '
+	git reset --hard &&
+	test_write_lines >file \
+		A B C one two three four five six seven D E F G H I J &&
+	git add file &&
+	test_write_lines >file \
+		one two A B C D E F G H I J two three four five six seven &&
+	git diff --color-moved=zebra -- file &&
+
+	git diff --color-moved=zebra --color -- file >actual.raw &&
+	grep -v "index" actual.raw | test_decode_color >actual &&
+	cat >expected <<-\EOF &&
+	<BOLD>diff --git a/file b/file<RESET>
+	<BOLD>--- a/file<RESET>
+	<BOLD>+++ b/file<RESET>
+	<CYAN>@@ -1,13 +1,8 @@<RESET>
+	<GREEN>+<RESET><GREEN>one<RESET>
+	<GREEN>+<RESET><GREEN>two<RESET>
+	 A<RESET>
+	 B<RESET>
+	 C<RESET>
+	<RED>-one<RESET>
+	<BOLD;MAGENTA>-two<RESET>
+	<BOLD;MAGENTA>-three<RESET>
+	<BOLD;MAGENTA>-four<RESET>
+	<BOLD;MAGENTA>-five<RESET>
+	<BOLD;MAGENTA>-six<RESET>
+	<BOLD;MAGENTA>-seven<RESET>
+	 D<RESET>
+	 E<RESET>
+	 F<RESET>
+	<CYAN>@@ -15,3 +10,9 @@<RESET> <RESET>G<RESET>
+	 H<RESET>
+	 I<RESET>
+	 J<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>two<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>three<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>four<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>five<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>six<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>seven<RESET>
+	EOF
+
+	test_cmp expected actual
+'
+
 test_expect_success 'move detection with submodules' '
 	test_create_repo bananas &&
 	echo ripe >bananas/recipe &&
@@ -2023,10 +2206,10 @@
 test_expect_success 'compare mixed whitespace delta across moved blocks' '
 
 	git reset --hard &&
-	tr Q_ "\t " <<-EOF >text.txt &&
-	${EMPTY}
-	____too short without
-	${EMPTY}
+	tr "^|Q_" "\f\v\t " <<-EOF >text.txt &&
+	^__
+	|____too short without
+	^
 	___being grouped across blank line
 	${EMPTY}
 	context
@@ -2045,7 +2228,7 @@
 	git add text.txt &&
 	git commit -m "add text.txt" &&
 
-	tr Q_ "\t " <<-EOF >text.txt &&
+	tr "^|Q_" "\f\v\t " <<-EOF >text.txt &&
 	context
 	lines
 	to
@@ -2056,7 +2239,7 @@
 	${EMPTY}
 	QQtoo short without
 	${EMPTY}
-	Q_______being grouped across blank line
+	^Q_______being grouped across blank line
 	${EMPTY}
 	Q_QThese two lines have had their
 	indentation reduced by four spaces
@@ -2068,16 +2251,16 @@
 		-c core.whitespace=space-before-tab \
 		diff --color --color-moved --ws-error-highlight=all \
 		--color-moved-ws=allow-indentation-change >actual.raw &&
-	grep -v "index" actual.raw | test_decode_color >actual &&
+	grep -v "index" actual.raw | tr "\f\v" "^|" | test_decode_color >actual &&
 
 	cat <<-\EOF >expected &&
 	<BOLD>diff --git a/text.txt b/text.txt<RESET>
 	<BOLD>--- a/text.txt<RESET>
 	<BOLD>+++ b/text.txt<RESET>
 	<CYAN>@@ -1,16 +1,16 @@<RESET>
-	<BOLD;MAGENTA>-<RESET>
-	<BOLD;MAGENTA>-<RESET><BOLD;MAGENTA>    too short without<RESET>
-	<BOLD;MAGENTA>-<RESET>
+	<BOLD;MAGENTA>-<RESET><BOLD;MAGENTA>^<RESET><BRED>  <RESET>
+	<BOLD;MAGENTA>-<RESET><BOLD;MAGENTA>|    too short without<RESET>
+	<BOLD;MAGENTA>-<RESET><BOLD;MAGENTA>^<RESET>
 	<BOLD;MAGENTA>-<RESET><BOLD;MAGENTA>   being grouped across blank line<RESET>
 	<BOLD;MAGENTA>-<RESET>
 	 <RESET>context<RESET>
@@ -2097,7 +2280,7 @@
 	<BOLD;YELLOW>+<RESET>
 	<BOLD;YELLOW>+<RESET>		<BOLD;YELLOW>too short without<RESET>
 	<BOLD;YELLOW>+<RESET>
-	<BOLD;YELLOW>+<RESET>	<BOLD;YELLOW>       being grouped across blank line<RESET>
+	<BOLD;YELLOW>+<RESET><BOLD;YELLOW>^	       being grouped across blank line<RESET>
 	<BOLD;YELLOW>+<RESET>
 	<BOLD;CYAN>+<RESET>	<BRED> <RESET>	<BOLD;CYAN>These two lines have had their<RESET>
 	<BOLD;CYAN>+<RESET><BOLD;CYAN>indentation reduced by four spaces<RESET>
diff --git a/t/t4018-diff-funcname.sh b/t/t4018-diff-funcname.sh
index 740696c..42a2b9a 100755
--- a/t/t4018-diff-funcname.sh
+++ b/t/t4018-diff-funcname.sh
@@ -75,7 +75,7 @@
 test_expect_success 'setup hunk header tests' '
 	for i in $diffpatterns
 	do
-		echo "$i-* diff=$i"
+		echo "$i-* diff=$i" || return 1
 	done > .gitattributes &&
 
 	# add all test files to the index
diff --git a/t/t4019-diff-wserror.sh b/t/t4019-diff-wserror.sh
index c68729a..d2b3109 100755
--- a/t/t4019-diff-wserror.sh
+++ b/t/t4019-diff-wserror.sh
@@ -287,9 +287,9 @@
 '
 
 test_expect_success 'color new trailing blank lines' '
-	{ echo a; echo b; echo; echo; } >x &&
+	test_write_lines a b "" "" >x &&
 	git add x &&
-	{ echo a; echo; echo; echo; echo c; echo; echo; echo; echo; } >x &&
+	test_write_lines a "" "" "" c "" "" "" "" >x &&
 	git diff --color x >output &&
 	cnt=$($grep_a "${blue_grep}" output | wc -l) &&
 	test $cnt = 2
diff --git a/t/t4020-diff-external.sh b/t/t4020-diff-external.sh
index e009826..54bb8ef 100755
--- a/t/t4020-diff-external.sh
+++ b/t/t4020-diff-external.sh
@@ -2,6 +2,7 @@
 
 test_description='external diff interface test'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4023-diff-rename-typechange.sh b/t/t4023-diff-rename-typechange.sh
index 47d6f35..7cb9909 100755
--- a/t/t4023-diff-rename-typechange.sh
+++ b/t/t4023-diff-rename-typechange.sh
@@ -55,7 +55,7 @@
 
 	git diff-tree five six -r --name-status -B -M | sort >actual &&
 	{
-		echo "R100	foo	bar"
+		echo "R100	foo	bar" &&
 		echo "R100	bar	foo"
 	} | sort >expect &&
 	test_cmp expect actual
@@ -66,7 +66,7 @@
 
 	git diff-tree one two -r --name-status -B -M | sort >actual &&
 	{
-		echo "R100	foo	bar"
+		echo "R100	foo	bar" &&
 		echo "R100	bar	foo"
 	} | sort >expect &&
 	test_cmp expect actual
@@ -78,7 +78,7 @@
 	git diff-tree three four -r --name-status -B -M | sort >actual &&
 	{
 		# see -B -M (#6) in t4008
-		echo "C100	foo	bar"
+		echo "C100	foo	bar" &&
 		echo "T100	foo"
 	} | sort >expect &&
 	test_cmp expect actual
diff --git a/t/t4024-diff-optimize-common.sh b/t/t4024-diff-optimize-common.sh
index 6b44ce1..e2f0eca 100755
--- a/t/t4024-diff-optimize-common.sh
+++ b/t/t4024-diff-optimize-common.sh
@@ -2,6 +2,7 @@
 
 test_description='common tail optimization'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 z=zzzzzzzz ;# 8
@@ -148,7 +149,7 @@
 
 	for n in $sample
 	do
-		git diff -U0 file-?$n
+		git diff -U0 file-?$n || return 1
 	done | zc >actual &&
 	test_cmp expect actual
 
diff --git a/t/t4025-hunk-header.sh b/t/t4025-hunk-header.sh
index 6356961..5397cb7 100755
--- a/t/t4025-hunk-header.sh
+++ b/t/t4025-hunk-header.sh
@@ -14,15 +14,9 @@
 
 	(
 		echo "A $NS" &&
-		for c in B C D E F G H I J K
-		do
-			echo "  $c"
-		done &&
+		printf "  %s\n" B C D E F G H I J K &&
 		echo "L  $NS" &&
-		for c in M N O P Q R S T U V
-		do
-			echo "  $c"
-		done
+		printf "  %s\n" M N O P Q R S T U V
 	) >file &&
 	git add file &&
 
diff --git a/t/t4026-color.sh b/t/t4026-color.sh
index cc73161..cc3f60d 100755
--- a/t/t4026-color.sh
+++ b/t/t4026-color.sh
@@ -60,6 +60,10 @@
 	color "blue bold dim ul blink reverse" "[1;2;4;5;7;34m"
 '
 
+test_expect_success 'reset fg bg attr...' '
+	color "reset blue bold dim ul blink reverse" "[;1;2;4;5;7;34m"
+'
+
 # note that nobold and nodim are the same code (22)
 test_expect_success 'attr negation' '
 	color "nobold nodim noul noblink noreverse" "[22;24;25;27m"
@@ -96,6 +100,18 @@
 	color "#ff00ff black" "[38;2;255;0;255;40m"
 '
 
+test_expect_success '"default" foreground' '
+	color "default" "[39m"
+'
+
+test_expect_success '"normal default" to clear background' '
+	color "normal default" "[49m"
+'
+
+test_expect_success '"default" can be combined with attributes' '
+	color "default default no-reverse bold" "[1;27;39;49m"
+'
+
 test_expect_success '"normal" yields no color at all"' '
 	color "normal black" "[40m"
 '
diff --git a/t/t4027-diff-submodule.sh b/t/t4027-diff-submodule.sh
index 94ef77e..6cef0da 100755
--- a/t/t4027-diff-submodule.sh
+++ b/t/t4027-diff-submodule.sh
@@ -2,6 +2,7 @@
 
 test_description='difference in submodules'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh
 
diff --git a/t/t4029-diff-trailing-space.sh b/t/t4029-diff-trailing-space.sh
index 32b6e9a..5f8ffef 100755
--- a/t/t4029-diff-trailing-space.sh
+++ b/t/t4029-diff-trailing-space.sh
@@ -4,6 +4,7 @@
 #
 test_description='diff honors config option, diff.suppressBlankEmpty'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 cat <<\EOF >expected ||
diff --git a/t/t4032-diff-inter-hunk-context.sh b/t/t4032-diff-inter-hunk-context.sh
index bada0cb..7db92d0 100755
--- a/t/t4032-diff-inter-hunk-context.sh
+++ b/t/t4032-diff-inter-hunk-context.sh
@@ -2,6 +2,7 @@
 
 test_description='diff hunk fusing'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 f() {
diff --git a/t/t4033-diff-patience.sh b/t/t4033-diff-patience.sh
index 113304d..f7be7f5 100755
--- a/t/t4033-diff-patience.sh
+++ b/t/t4033-diff-patience.sh
@@ -2,6 +2,7 @@
 
 test_description='patience diff algorithm'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff-alternative.sh
 
diff --git a/t/t4034-diff-words.sh b/t/t4034-diff-words.sh
index 561c582..d5abcf4 100755
--- a/t/t4034-diff-words.sh
+++ b/t/t4034-diff-words.sh
@@ -2,6 +2,7 @@
 
 test_description='word diff colors'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh
 
diff --git a/t/t4035-diff-quiet.sh b/t/t4035-diff-quiet.sh
index 0352bf8..76f8034 100755
--- a/t/t4035-diff-quiet.sh
+++ b/t/t4035-diff-quiet.sh
@@ -2,6 +2,7 @@
 
 test_description='Return value of diffs'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t4037-diff-r-t-dirs.sh b/t/t4037-diff-r-t-dirs.sh
index f5ce3b2..b5f96fe 100755
--- a/t/t4037-diff-r-t-dirs.sh
+++ b/t/t4037-diff-r-t-dirs.sh
@@ -2,6 +2,7 @@
 
 test_description='diff -r -t shows directory additions and deletions'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4038-diff-combined.sh b/t/t4038-diff-combined.sh
index aeac203..9a292ba 100755
--- a/t/t4038-diff-combined.sh
+++ b/t/t4038-diff-combined.sh
@@ -100,7 +100,7 @@
 	for i in $(test_seq 1 40)
 	do
 		blob=$(echo file$i | git hash-object --stdin -w) &&
-		trees="$trees$(echo "100644 blob $blob	file" | git mktree)$LF"
+		trees="$trees$(echo "100644 blob $blob	file" | git mktree)$LF" || return 1
 	done
 '
 
diff --git a/t/t4040-whitespace-status.sh b/t/t4040-whitespace-status.sh
index 3c728a3..e70e020 100755
--- a/t/t4040-whitespace-status.sh
+++ b/t/t4040-whitespace-status.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='diff --exit-code with whitespace'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4046-diff-unmerged.sh b/t/t4046-diff-unmerged.sh
index ff7cfd8..0ae0cd3 100755
--- a/t/t4046-diff-unmerged.sh
+++ b/t/t4046-diff-unmerged.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='diff with unmerged index entries'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
@@ -18,7 +20,7 @@
 			for t in o x
 			do
 				path="$b$o$t" &&
-				case "$path" in ooo) continue ;; esac
+				case "$path" in ooo) continue ;; esac &&
 				paths="$paths$path " &&
 				p="	$path" &&
 				case "$b" in x) echo "$m1$p" ;; esac &&
@@ -37,7 +39,7 @@
 	for path in $paths
 	do
 		>"$path" &&
-		echo ":000000 100644 $ZERO_OID $ZERO_OID U	$path"
+		echo ":000000 100644 $ZERO_OID $ZERO_OID U	$path" || return 1
 	done >diff-files-0.expect &&
 	git diff-files -0 >diff-files-0.actual &&
 	test_cmp diff-files-0.expect diff-files-0.actual
@@ -50,7 +52,7 @@
 		echo ":000000 100644 $ZERO_OID $ZERO_OID U	$path" &&
 		case "$path" in
 		x??) echo ":100644 100644 $blob1 $ZERO_OID M	$path"
-		esac
+		esac || return 1
 	done >diff-files-1.expect &&
 	git diff-files -1 >diff-files-1.actual &&
 	test_cmp diff-files-1.expect diff-files-1.actual
@@ -63,7 +65,7 @@
 		echo ":000000 100644 $ZERO_OID $ZERO_OID U	$path" &&
 		case "$path" in
 		?x?) echo ":100644 100644 $blob2 $ZERO_OID M	$path"
-		esac
+		esac || return 1
 	done >diff-files-2.expect &&
 	git diff-files -2 >diff-files-2.actual &&
 	test_cmp diff-files-2.expect diff-files-2.actual &&
@@ -78,7 +80,7 @@
 		echo ":000000 100644 $ZERO_OID $ZERO_OID U	$path" &&
 		case "$path" in
 		??x) echo ":100644 100644 $blob3 $ZERO_OID M	$path"
-		esac
+		esac || return 1
 	done >diff-files-3.expect &&
 	git diff-files -3 >diff-files-3.actual &&
 	test_cmp diff-files-3.expect diff-files-3.actual
diff --git a/t/t4049-diff-stat-count.sh b/t/t4049-diff-stat-count.sh
index 53061b1..0a4fc73 100755
--- a/t/t4049-diff-stat-count.sh
+++ b/t/t4049-diff-stat-count.sh
@@ -2,6 +2,8 @@
 # Copyright (c) 2011, Google Inc.
 
 test_description='diff --stat-count'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
@@ -51,7 +53,7 @@
 	git rm -f d &&
 	for stage in 1 2 3
 	do
-		sed -e "s/ 0	a/ $stage	d/" x
+		sed -e "s/ 0	a/ $stage	d/" x || return 1
 	done |
 	git update-index --index-info &&
 	echo d >d &&
diff --git a/t/t4050-diff-histogram.sh b/t/t4050-diff-histogram.sh
index fd3e86a..c61b30f 100755
--- a/t/t4050-diff-histogram.sh
+++ b/t/t4050-diff-histogram.sh
@@ -2,6 +2,7 @@
 
 test_description='histogram diff algorithm'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff-alternative.sh
 
diff --git a/t/t4052-stat-output.sh b/t/t4052-stat-output.sh
index 9eba436..b5c281e 100755
--- a/t/t4052-stat-output.sh
+++ b/t/t4052-stat-output.sh
@@ -101,7 +101,7 @@
 	i=0 &&
 	while test $i -lt 1000
 	do
-		echo $i && i=$(($i + 1))
+		echo $i && i=$(($i + 1)) || return 1
 	done >abcd &&
 	git commit -m message abcd
 '
diff --git a/t/t4054-diff-bogus-tree.sh b/t/t4054-diff-bogus-tree.sh
index 8c95f15..294fb55 100755
--- a/t/t4054-diff-bogus-tree.sh
+++ b/t/t4054-diff-bogus-tree.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='test diff with a bogus tree containing the null sha1'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'create bogus tree' '
diff --git a/t/t4057-diff-combined-paths.sh b/t/t4057-diff-combined-paths.sh
index 7e5b74f..04b8a15 100755
--- a/t/t4057-diff-combined-paths.sh
+++ b/t/t4057-diff-combined-paths.sh
@@ -18,13 +18,13 @@
 	for i in $(test_seq 1 9)
 	do
 		echo $i >$i.txt &&
-		git add $i.txt
+		git add $i.txt || return 1
 	done &&
 	git commit -m "init" &&
 	git checkout -b side &&
 	for i in $(test_seq 2 9)
 	do
-		echo $i/2 >>$i.txt
+		echo $i/2 >>$i.txt || return 1
 	done &&
 	git commit -a -m "side 2-9" &&
 	git checkout main &&
@@ -40,14 +40,14 @@
 	git checkout side &&
 	for i in $(test_seq 2 9)
 	do
-		echo $i/3 >>$i.txt
+		echo $i/3 >>$i.txt || return 1
 	done &&
 	echo "4side" >>4.txt &&
 	git commit -a -m "side 2-9 +4" &&
 	git checkout main &&
 	for i in $(test_seq 1 9)
 	do
-		echo $i/3 >>$i.txt
+		echo $i/3 >>$i.txt || return 1
 	done &&
 	echo "4main" >>4.txt &&
 	git commit -a -m "main 1-9 +4" &&
@@ -69,13 +69,13 @@
 	git checkout side &&
 	for i in $(test_seq 5 9)
 	do
-		echo $i/4 >>$i.txt
+		echo $i/4 >>$i.txt || return 1
 	done &&
 	git commit -a -m "side 5-9" &&
 	git checkout main &&
 	for i in $(test_seq 1 3)
 	do
-		echo $i/4 >>$i.txt
+		echo $i/4 >>$i.txt || return 1
 	done &&
 	git commit -a -m "main 1-3 +4hello" &&
 	git merge side &&
@@ -90,13 +90,13 @@
 	git checkout side &&
 	for i in $(test_seq 5 9)
 	do
-		echo $i/5 >>$i.txt
+		echo $i/5 >>$i.txt || return 1
 	done &&
 	git commit -a -m "side 5-9" &&
 	git checkout main &&
 	for i in $(test_seq 1 3)
 	do
-		echo $i/4 >>$i.txt
+		echo $i/4 >>$i.txt || return 1
 	done &&
 	git commit -a -m "main 1-3" &&
 	git merge side &&
diff --git a/t/t4062-diff-pickaxe.sh b/t/t4062-diff-pickaxe.sh
index 1130c80..9aaa068 100755
--- a/t/t4062-diff-pickaxe.sh
+++ b/t/t4062-diff-pickaxe.sh
@@ -5,6 +5,7 @@
 
 test_description='Pickaxe options'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4063-diff-blobs.sh b/t/t4063-diff-blobs.sh
index bc69e26..7e6c9d6 100755
--- a/t/t4063-diff-blobs.sh
+++ b/t/t4063-diff-blobs.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='test direct comparison of blobs via git-diff'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 run_diff () {
diff --git a/t/t4100-apply-stat.sh b/t/t4100-apply-stat.sh
index 9b433de..d503547 100755
--- a/t/t4100-apply-stat.sh
+++ b/t/t4100-apply-stat.sh
@@ -6,6 +6,8 @@
 test_description='git apply --stat --summary test, with --recount
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 UNC='s/^\(@@ -[1-9][0-9]*\),[0-9]* \(+[1-9][0-9]*\),[0-9]* @@/\1,999 \2,999 @@/'
diff --git a/t/t4101-apply-nonl.sh b/t/t4101-apply-nonl.sh
index e3443d0..b116919 100755
--- a/t/t4101-apply-nonl.sh
+++ b/t/t4101-apply-nonl.sh
@@ -6,6 +6,8 @@
 test_description='git apply should handle files with incomplete lines.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # setup
diff --git a/t/t4102-apply-rename.sh b/t/t4102-apply-rename.sh
index fae3059..d1e06fc 100755
--- a/t/t4102-apply-rename.sh
+++ b/t/t4102-apply-rename.sh
@@ -6,6 +6,8 @@
 test_description='git apply handling copy/rename patch.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # setup
diff --git a/t/t4105-apply-fuzz.sh b/t/t4105-apply-fuzz.sh
index 3266e39..ed814a8 100755
--- a/t/t4105-apply-fuzz.sh
+++ b/t/t4105-apply-fuzz.sh
@@ -2,6 +2,8 @@
 
 test_description='apply with fuzz and offset'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 dotest () {
@@ -15,15 +17,9 @@
 
 test_expect_success setup '
 
-	for i in 1 2 3 4 5 6 7 8 9 10 11 12
-	do
-		echo $i
-	done >file &&
+	test_write_lines 1 2 3 4 5 6 7 8 9 10 11 12 >file &&
 	git update-index --add file &&
-	for i in 1 2 3 4 5 6 7 a b c d e 8 9 10 11 12
-	do
-		echo $i
-	done >file &&
+	test_write_lines 1 2 3 4 5 6 7 a b c d e 8 9 10 11 12 >file &&
 	cat file >expect &&
 	git diff >O0.diff &&
 
diff --git a/t/t4106-apply-stdin.sh b/t/t4106-apply-stdin.sh
index 72467a1..5c150f3 100755
--- a/t/t4106-apply-stdin.sh
+++ b/t/t4106-apply-stdin.sh
@@ -2,6 +2,8 @@
 
 test_description='git apply --numstat - <patch'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
@@ -18,7 +20,10 @@
 '
 
 test_expect_success 'git apply --numstat - < patch patch' '
-	for i in 1 2; do echo "1	1	text"; done >expect &&
+	cat >expect <<-\EOF &&
+	1	1	text
+	1	1	text
+	EOF
 	git apply --numstat - < patch patch >actual &&
 	test_cmp expect actual
 '
diff --git a/t/t4108-apply-threeway.sh b/t/t4108-apply-threeway.sh
index cc3aa33..c558282 100755
--- a/t/t4108-apply-threeway.sh
+++ b/t/t4108-apply-threeway.sh
@@ -275,4 +275,22 @@
 	git apply --3way --index bin.diff
 '
 
+test_expect_success 'apply delete then new patch with 3way' '
+	git reset --hard main &&
+	test_write_lines 2 > delnew &&
+	git add delnew &&
+	git diff --cached >> new.patch &&
+	git reset --hard &&
+	test_write_lines 1 > delnew &&
+	git add delnew &&
+	git commit -m "delnew" &&
+	rm delnew &&
+	git diff >> delete-then-new.patch &&
+	cat new.patch >> delete-then-new.patch &&
+
+	git checkout -- . &&
+	# Apply must succeed.
+	git apply --3way delete-then-new.patch
+'
+
 test_done
diff --git a/t/t4109-apply-multifrag.sh b/t/t4109-apply-multifrag.sh
index ac58083..4dc6d8e 100755
--- a/t/t4109-apply-multifrag.sh
+++ b/t/t4109-apply-multifrag.sh
@@ -6,6 +6,8 @@
 
 test_description='git apply test patches with multiple fragments.'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 cp "$TEST_DIRECTORY/t4109/patch1.patch" .
diff --git a/t/t4110-apply-scan.sh b/t/t4110-apply-scan.sh
index 09f5811..266302a 100755
--- a/t/t4110-apply-scan.sh
+++ b/t/t4110-apply-scan.sh
@@ -7,6 +7,8 @@
 test_description='git apply test for patches which require scanning forwards and backwards.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'git apply scan' '
diff --git a/t/t4112-apply-renames.sh b/t/t4112-apply-renames.sh
index f9ad183..d53aa42 100755
--- a/t/t4112-apply-renames.sh
+++ b/t/t4112-apply-renames.sh
@@ -7,6 +7,8 @@
 
 '
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # setup
diff --git a/t/t4115-apply-symlink.sh b/t/t4115-apply-symlink.sh
index 872fcda..d0f3ede 100755
--- a/t/t4115-apply-symlink.sh
+++ b/t/t4115-apply-symlink.sh
@@ -7,6 +7,7 @@
 
 '
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4116-apply-reverse.sh b/t/t4116-apply-reverse.sh
index b99e65c..a9f4ddd 100755
--- a/t/t4116-apply-reverse.sh
+++ b/t/t4116-apply-reverse.sh
@@ -7,18 +7,20 @@
 
 '
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
 
-	for i in a b c d e f g h i j k l m n; do echo $i; done >file1 &&
+	test_write_lines a b c d e f g h i j k l m n >file1 &&
 	perl -pe "y/ijk/\\000\\001\\002/" <file1 >file2 &&
 
 	git add file1 file2 &&
 	git commit -m initial &&
 	git tag initial &&
 
-	for i in a b c g h i J K L m o n p q; do echo $i; done >file1 &&
+	test_write_lines a b c g h i J K L m o n p q >file1 &&
 	perl -pe "y/mon/\\000\\001\\002/" <file1 >file2 &&
 
 	git commit -a -m second &&
diff --git a/t/t4117-apply-reject.sh b/t/t4117-apply-reject.sh
index 0ee93fe..c86d05a 100755
--- a/t/t4117-apply-reject.sh
+++ b/t/t4117-apply-reject.sh
@@ -10,25 +10,16 @@
 . ./test-lib.sh
 
 test_expect_success setup '
-	for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
-	do
-		echo $i
-	done >file1 &&
+	test_write_lines 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 >file1 &&
 	cat file1 >saved.file1 &&
 	git update-index --add file1 &&
 	git commit -m initial &&
 
-	for i in 1 2 A B 4 5 6 7 8 9 10 11 12 C 13 14 15 16 17 18 19 20 D 21
-	do
-		echo $i
-	done >file1 &&
+	test_write_lines 1 2 A B 4 5 6 7 8 9 10 11 12 C 13 14 15 16 17 18 19 20 D 21 >file1 &&
 	git diff >patch.1 &&
 	cat file1 >clean &&
 
-	for i in 1 E 2 3 4 5 6 7 8 9 10 11 12 C 13 14 15 16 17 18 19 20 F 21
-	do
-		echo $i
-	done >expected &&
+	test_write_lines 1 E 2 3 4 5 6 7 8 9 10 11 12 C 13 14 15 16 17 18 19 20 F 21 >expected &&
 
 	mv file1 file2 &&
 	git update-index --add --remove file1 file2 &&
@@ -38,10 +29,7 @@
 	mv saved.file1 file1 &&
 	git update-index --add --remove file1 file2 &&
 
-	for i in 1 E 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 F 21
-	do
-		echo $i
-	done >file1 &&
+	test_write_lines 1 E 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 F 21 >file1 &&
 
 	cat file1 >saved.file1
 '
diff --git a/t/t4118-apply-empty-context.sh b/t/t4118-apply-empty-context.sh
index 65f2e4c..69c9c48 100755
--- a/t/t4118-apply-empty-context.sh
+++ b/t/t4118-apply-empty-context.sh
@@ -7,14 +7,12 @@
 
 '
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
-	{
-		echo; echo;
-		echo A; echo B; echo C;
-		echo;
-	} >file1 &&
+	test_write_lines "" "" A B C "" >file1 &&
 	cat file1 >file1.orig &&
 	{
 		cat file1 &&
diff --git a/t/t4119-apply-config.sh b/t/t4119-apply-config.sh
index a9a0583..208c961 100755
--- a/t/t4119-apply-config.sh
+++ b/t/t4119-apply-config.sh
@@ -7,6 +7,8 @@
 
 '
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4121-apply-diffs.sh b/t/t4121-apply-diffs.sh
index b45454a..a80cec9 100755
--- a/t/t4121-apply-diffs.sh
+++ b/t/t4121-apply-diffs.sh
@@ -4,6 +4,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 echo '1
diff --git a/t/t4123-apply-shrink.sh b/t/t4123-apply-shrink.sh
index 984157f..dfa053f 100755
--- a/t/t4123-apply-shrink.sh
+++ b/t/t4123-apply-shrink.sh
@@ -2,6 +2,8 @@
 
 test_description='apply a patch that is larger than the preimage'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 cat >F  <<\EOF
@@ -45,8 +47,8 @@
 		echo Oops, should not have succeeded
 		false
 	else
-		status=$?
-		echo "Status was $status"
+		status=$? &&
+		echo "Status was $status" &&
 		if test -f .git/index.lock
 		then
 			echo Oops, should not have crashed
diff --git a/t/t4124-apply-ws-rule.sh b/t/t4124-apply-ws-rule.sh
index 0ca2982..485c7d2 100755
--- a/t/t4124-apply-ws-rule.sh
+++ b/t/t4124-apply-ws-rule.sh
@@ -230,10 +230,10 @@
 	test_might_fail git config --unset core.whitespace &&
 	rm -f .gitattributes &&
 
-	{ echo a; echo b; echo c; } >one &&
+	test_write_lines a b c >one &&
 	git add one &&
-	{ echo a; echo b; echo c; } >expect &&
-	{ cat expect; echo; } >one &&
+	test_write_lines a b c >expect &&
+	{ cat expect && echo; } >one &&
 	git diff -- one >patch &&
 
 	git checkout one &&
@@ -242,10 +242,10 @@
 '
 
 test_expect_success 'blank at EOF with --whitespace=fix (2)' '
-	{ echo a; echo b; echo c; } >one &&
+	test_write_lines a b c >one &&
 	git add one &&
-	{ echo a; echo c; } >expect &&
-	{ cat expect; echo; echo; } >one &&
+	test_write_lines a b >expect &&
+	{ cat expect && test_write_lines "" ""; } >one &&
 	git diff -- one >patch &&
 
 	git checkout one &&
@@ -254,10 +254,10 @@
 '
 
 test_expect_success 'blank at EOF with --whitespace=fix (3)' '
-	{ echo a; echo b; echo; } >one &&
+	test_write_lines a b "" >one &&
 	git add one &&
-	{ echo a; echo c; echo; } >expect &&
-	{ cat expect; echo; echo; } >one &&
+	test_write_lines a c "" >expect &&
+	{ cat expect && test_write_lines "" ""; } >one &&
 	git diff -- one >patch &&
 
 	git checkout one &&
@@ -266,9 +266,9 @@
 '
 
 test_expect_success 'blank at end of hunk, not at EOF with --whitespace=fix' '
-	{ echo a; echo b; echo; echo; echo; echo; echo; echo d; } >one &&
+	test_write_lines a b "" "" "" "" "" d >one &&
 	git add one &&
-	{ echo a; echo c; echo; echo; echo; echo; echo; echo; echo d; } >expect &&
+	test_write_lines a b "" "" "" "" "" "" d >expect &&
 	cp expect one &&
 	git diff -- one >patch &&
 
@@ -278,7 +278,7 @@
 '
 
 test_expect_success 'blank at EOF with --whitespace=warn' '
-	{ echo a; echo b; echo c; } >one &&
+	test_write_lines a b c >one &&
 	git add one &&
 	echo >>one &&
 	cat one >expect &&
@@ -291,7 +291,7 @@
 '
 
 test_expect_success 'blank at EOF with --whitespace=error' '
-	{ echo a; echo b; echo c; } >one &&
+	test_write_lines a b c >one &&
 	git add one &&
 	cat one >expect &&
 	echo >>one &&
@@ -304,7 +304,7 @@
 '
 
 test_expect_success 'blank but not empty at EOF' '
-	{ echo a; echo b; echo c; } >one &&
+	test_write_lines a b c >one &&
 	git add one &&
 	echo "   " >>one &&
 	cat one >expect &&
@@ -317,13 +317,13 @@
 '
 
 test_expect_success 'applying beyond EOF requires one non-blank context line' '
-	{ echo; echo; echo; echo; } >one &&
+	test_write_lines "" "" "" "" >one &&
 	git add one &&
-	{ echo b; } >>one &&
+	echo b >>one &&
 	git diff -- one >patch &&
 
 	git checkout one &&
-	{ echo a; echo; } >one &&
+	test_write_lines a "" >one &&
 	cp one expect &&
 	test_must_fail git apply --whitespace=fix patch &&
 	test_cmp expect one &&
@@ -333,7 +333,7 @@
 
 test_expect_success 'tons of blanks at EOF should not apply' '
 	for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16; do
-		echo; echo; echo; echo;
+		test_write_lines "" "" "" "" || return 1
 	done >one &&
 	git add one &&
 	echo a >>one &&
@@ -362,9 +362,9 @@
 '
 
 test_expect_success 'two missing blank lines at end with --whitespace=fix' '
-	{ echo a; echo; echo b; echo c; } >one &&
+	test_write_lines a "" b c >one &&
 	cp one no-blank-lines &&
-	{ echo; echo; } >>one &&
+	test_write_lines "" "" >>one &&
 	git add one &&
 	echo d >>one &&
 	cp one expect &&
@@ -381,9 +381,9 @@
 '
 
 test_expect_success 'missing blank line at end, insert before end, --whitespace=fix' '
-	{ echo a; echo; } >one &&
+	test_write_lines a "" >one &&
 	git add one &&
-	{ echo b; echo a; echo; } >one &&
+	test_write_lines b a "" >one &&
 	cp one expect &&
 	git diff -- one >patch &&
 	echo a >one &&
@@ -393,10 +393,10 @@
 '
 
 test_expect_success 'shrink file with tons of missing blanks at end of file' '
-	{ echo a; echo b; echo c; } >one &&
+	test_write_lines a b c >one &&
 	cp one no-blank-lines &&
 	for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16; do
-		echo; echo; echo; echo;
+		test_write_lines "" "" "" "" || return 1
 	done >>one &&
 	git add one &&
 	echo a >one &&
@@ -412,9 +412,9 @@
 '
 
 test_expect_success 'missing blanks at EOF must only match blank lines' '
-	{ echo a; echo b; } >one &&
+	test_write_lines a b >one &&
 	git add one &&
-	{ echo c; echo d; } >>one &&
+	test_write_lines c d >>one &&
 	git diff -- one >patch &&
 
 	echo a >one &&
@@ -434,9 +434,9 @@
 	git add one &&
 	echo d >>one &&
 	git diff -- one >patch &&
-	{ echo a; echo b; echo c; } >one &&
+	test_write_lines a b c >one &&
 	cp one expect &&
-	{ echo; echo d; } >>expect &&
+	test_write_lines "" d >>expect &&
 	git add one &&
 
 	git apply --whitespace=fix patch &&
@@ -455,7 +455,7 @@
 	echo d >>one &&
 	cp one expect &&
 	git diff -- one >patch &&
-	{ echo a; echo b; echo c; } >one &&
+	test_write_lines a b c >one &&
 	git add one &&
 
 	git checkout-index -f one &&
diff --git a/t/t4125-apply-ws-fuzz.sh b/t/t4125-apply-ws-fuzz.sh
index 9671de7..090987c 100755
--- a/t/t4125-apply-ws-fuzz.sh
+++ b/t/t4125-apply-ws-fuzz.sh
@@ -10,10 +10,7 @@
 	git add file &&
 
 	# file-0 is full of whitespace breakages
-	for l in a bb c d eeee f ggg h
-	do
-		echo "$l "
-	done >file-0 &&
+	printf "%s \n" a bb c d eeee f ggg h >file-0 &&
 
 	# patch-0 creates a whitespace broken file
 	cat file-0 >file &&
diff --git a/t/t4126-apply-empty.sh b/t/t4126-apply-empty.sh
index ceb6a79..33860d3 100755
--- a/t/t4126-apply-empty.sh
+++ b/t/t4126-apply-empty.sh
@@ -2,6 +2,8 @@
 
 test_description='apply empty'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
@@ -9,10 +11,9 @@
 	git add empty &&
 	test_tick &&
 	git commit -m initial &&
-	for i in a b c d e
-	do
-		echo $i
-	done >empty &&
+	git commit --allow-empty -m "empty commit" &&
+	git format-patch --always HEAD~ >empty.patch &&
+	test_write_lines a b c d e >empty &&
 	cat empty >expect &&
 	git diff |
 	sed -e "/^diff --git/d" \
@@ -25,30 +26,42 @@
 '
 
 test_expect_success 'apply empty' '
-	git reset --hard &&
 	rm -f missing &&
+	test_when_finished "git reset --hard" &&
 	git apply patch0 &&
 	test_cmp expect empty
 '
 
+test_expect_success 'apply empty patch fails' '
+	test_when_finished "git reset --hard" &&
+	test_must_fail git apply empty.patch &&
+	test_must_fail git apply - </dev/null
+'
+
+test_expect_success 'apply with --allow-empty succeeds' '
+	test_when_finished "git reset --hard" &&
+	git apply --allow-empty empty.patch &&
+	git apply --allow-empty - </dev/null
+'
+
 test_expect_success 'apply --index empty' '
-	git reset --hard &&
 	rm -f missing &&
+	test_when_finished "git reset --hard" &&
 	git apply --index patch0 &&
 	test_cmp expect empty &&
 	git diff --exit-code
 '
 
 test_expect_success 'apply create' '
-	git reset --hard &&
 	rm -f missing &&
+	test_when_finished "git reset --hard" &&
 	git apply patch1 &&
 	test_cmp expect missing
 '
 
 test_expect_success 'apply --index create' '
-	git reset --hard &&
 	rm -f missing &&
+	test_when_finished "git reset --hard" &&
 	git apply --index patch1 &&
 	test_cmp expect missing &&
 	git diff --exit-code
diff --git a/t/t4127-apply-same-fn.sh b/t/t4127-apply-same-fn.sh
index 305b7e6..aa5cfae 100755
--- a/t/t4127-apply-same-fn.sh
+++ b/t/t4127-apply-same-fn.sh
@@ -2,6 +2,8 @@
 
 test_description='apply same filename'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 modify () {
@@ -10,10 +12,7 @@
 }
 
 test_expect_success setup '
-	for i in a b c d e f g h i j k l m
-	do
-		echo $i
-	done >same_fn &&
+	test_write_lines a b c d e f g h i j k l m >same_fn &&
 	cp same_fn other_fn &&
 	git add same_fn other_fn &&
 	git commit -m initial
diff --git a/t/t4128-apply-root.sh b/t/t4128-apply-root.sh
index 6cc741a..cb3181e 100755
--- a/t/t4128-apply-root.sh
+++ b/t/t4128-apply-root.sh
@@ -2,6 +2,8 @@
 
 test_description='apply same filename'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t4129-apply-samemode.sh b/t/t4129-apply-samemode.sh
index 576632f..a1c7686 100755
--- a/t/t4129-apply-samemode.sh
+++ b/t/t4129-apply-samemode.sh
@@ -2,6 +2,8 @@
 
 test_description='applying patch with mode bits'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4130-apply-criss-cross-rename.sh b/t/t4130-apply-criss-cross-rename.sh
index f8a313b..f3ea632 100755
--- a/t/t4130-apply-criss-cross-rename.sh
+++ b/t/t4130-apply-criss-cross-rename.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='git apply handling criss-cross rename patch.'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 create_file() {
diff --git a/t/t4132-apply-removal.sh b/t/t4132-apply-removal.sh
index fec1d6f..c1e3049 100755
--- a/t/t4132-apply-removal.sh
+++ b/t/t4132-apply-removal.sh
@@ -4,6 +4,8 @@
 
 test_description='git-apply notices removal patches generated by GNU diff'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4133-apply-filenames.sh b/t/t4133-apply-filenames.sh
index c5ed3b1..35f1060 100755
--- a/t/t4133-apply-filenames.sh
+++ b/t/t4133-apply-filenames.sh
@@ -5,6 +5,8 @@
 
 test_description='git apply filename consistency check'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4134-apply-submodule.sh b/t/t4134-apply-submodule.sh
index d1c16ba..aceb4c4 100755
--- a/t/t4134-apply-submodule.sh
+++ b/t/t4134-apply-submodule.sh
@@ -5,6 +5,8 @@
 
 test_description='git apply submodule tests'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t4136-apply-check.sh b/t/t4136-apply-check.sh
index 4c3f264..dfec1c5 100755
--- a/t/t4136-apply-check.sh
+++ b/t/t4136-apply-check.sh
@@ -2,6 +2,8 @@
 
 test_description='git apply should exit non-zero with unrecognized input.'
 
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t4138-apply-ws-expansion.sh b/t/t4138-apply-ws-expansion.sh
index b19faeb..8bbf826 100755
--- a/t/t4138-apply-ws-expansion.sh
+++ b/t/t4138-apply-ws-expansion.sh
@@ -29,8 +29,8 @@
 	x=1 &&
 	while test $x -lt $n
 	do
-		printf "%63s%d\n" "" $x >>after
-		x=$(( $x + 1 ))
+		printf "%63s%d\n" "" $x >>after &&
+		x=$(( $x + 1 )) || return 1
 	done &&
 	printf "\t%s\n" d e f >>after &&
 	test_expect_code 1 git diff --no-index before after >patch2.patch.raw &&
@@ -40,8 +40,8 @@
 	x=1 &&
 	while test $x -lt $n
 	do
-		printf "%63s%d\n" "" $x >>expect-2
-		x=$(( $x + 1 ))
+		printf "%63s%d\n" "" $x >>expect-2 &&
+		x=$(( $x + 1 )) || return 1
 	done &&
 	printf "%64s\n" d e f >>expect-2 &&
 
@@ -52,8 +52,8 @@
 	x=0 &&
 	while test $x -lt $n
 	do
-		printf "%63s%02d\n" "" $x >>after
-		x=$(( $x + 1 ))
+		printf "%63s%02d\n" "" $x >>after &&
+		x=$(( $x + 1 )) || return 1
 	done &&
 	printf "\t%s\n" d e f >>after &&
 	test_expect_code 1 git diff --no-index before after >patch3.patch.raw &&
@@ -63,8 +63,8 @@
 	x=0 &&
 	while test $x -lt $n
 	do
-		printf "%63s%02d\n" "" $x >>expect-3
-		x=$(( $x + 1 ))
+		printf "%63s%02d\n" "" $x >>expect-3 &&
+		x=$(( $x + 1 )) || return 1
 	done &&
 	printf "%64s\n" d e f >>expect-3 &&
 
@@ -73,16 +73,16 @@
 	x=0 &&
 	while test $x -lt 50
 	do
-		printf "\t%02d\n" $x >>before
-		x=$(( $x + 1 ))
+		printf "\t%02d\n" $x >>before &&
+		x=$(( $x + 1 )) || return 1
 	done &&
 	cat before >after &&
 	printf "%64s\n" a b c >>after &&
 	while test $x -lt 100
 	do
-		printf "\t%02d\n" $x >>before
-		printf "\t%02d\n" $x >>after
-		x=$(( $x + 1 ))
+		printf "\t%02d\n" $x >>before &&
+		printf "\t%02d\n" $x >>after &&
+		x=$(( $x + 1 )) || return 1
 	done &&
 	test_expect_code 1 git diff --no-index before after >patch4.patch.raw &&
 	sed -e "s/before/test-4/" -e "s/after/test-4/" patch4.patch.raw >patch4.patch &&
@@ -90,16 +90,16 @@
 	x=0 &&
 	while test $x -lt 50
 	do
-		printf "%63s%02d\n" "" $x >>test-4
-		x=$(( $x + 1 ))
+		printf "%63s%02d\n" "" $x >>test-4 &&
+		x=$(( $x + 1 )) || return 1
 	done &&
 	cat test-4 >expect-4 &&
 	printf "%64s\n" a b c >>expect-4 &&
 	while test $x -lt 100
 	do
-		printf "%63s%02d\n" "" $x >>test-4
-		printf "%63s%02d\n" "" $x >>expect-4
-		x=$(( $x + 1 ))
+		printf "%63s%02d\n" "" $x >>test-4 &&
+		printf "%63s%02d\n" "" $x >>expect-4 &&
+		x=$(( $x + 1 )) || return 1
 	done &&
 
 	git config core.whitespace tab-in-indent,tabwidth=63 &&
diff --git a/t/t4139-apply-escape.sh b/t/t4139-apply-escape.sh
index 45b5660..e5c7439 100755
--- a/t/t4139-apply-escape.sh
+++ b/t/t4139-apply-escape.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='paths written by git-apply cannot escape the working tree'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # tests will try to write to ../foo, and we do not
diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index 2aaaa0d..6caff0c 100755
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh
@@ -116,7 +116,7 @@
 		git format-patch --stdout first | sed -e "1d"
 	} | append_cr >patch1-crlf.eml &&
 	{
-		printf "%255s\\n" ""
+		printf "%255s\\n" "" &&
 		echo "X-Fake-Field: Line One" &&
 		echo "X-Fake-Field: Line Two" &&
 		echo "X-Fake-Field: Line Three" &&
@@ -196,6 +196,12 @@
 
 	git format-patch -M --stdout lorem^ >rename-add.patch &&
 
+	git checkout -b empty-commit &&
+	git commit -m "empty commit" --allow-empty &&
+
+	: >empty.patch &&
+	git format-patch --always --stdout empty-commit^ >empty-commit.patch &&
+
 	# reset time
 	sane_unset test_tick &&
 	test_tick
@@ -1152,4 +1158,105 @@
 	git -C client am ../patch
 '
 
+test_expect_success 'an empty input file is error regardless of --empty option' '
+	test_when_finished "git am --abort || :" &&
+	test_must_fail git am --empty=drop empty.patch 2>actual &&
+	echo "Patch format detection failed." >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'invalid when passing the --empty option alone' '
+	test_when_finished "git am --abort || :" &&
+	git checkout empty-commit^ &&
+	test_must_fail git am --empty empty-commit.patch 2>err &&
+	echo "error: Invalid value for --empty: empty-commit.patch" >expected &&
+	test_cmp expected err
+'
+
+test_expect_success 'a message without a patch is an error (default)' '
+	test_when_finished "git am --abort || :" &&
+	test_must_fail git am empty-commit.patch >err &&
+	grep "Patch is empty" err
+'
+
+test_expect_success 'a message without a patch is an error where an explicit "--empty=stop" is given' '
+	test_when_finished "git am --abort || :" &&
+	test_must_fail git am --empty=stop empty-commit.patch >err &&
+	grep "Patch is empty." err
+'
+
+test_expect_success 'a message without a patch will be skipped when "--empty=drop" is given' '
+	git am --empty=drop empty-commit.patch >output &&
+	git rev-parse empty-commit^ >expected &&
+	git rev-parse HEAD >actual &&
+	test_cmp expected actual &&
+	grep "Skipping: empty commit" output
+'
+
+test_expect_success 'record as an empty commit when meeting e-mail message that lacks a patch' '
+	git am --empty=keep empty-commit.patch >output &&
+	test_path_is_missing .git/rebase-apply &&
+	git show empty-commit --format="%B" >expected &&
+	git show HEAD --format="%B" >actual &&
+	grep -f actual expected &&
+	grep "Creating an empty commit: empty commit" output
+'
+
+test_expect_success 'skip an empty patch in the middle of an am session' '
+	git checkout empty-commit^ &&
+	test_must_fail git am empty-commit.patch >err &&
+	grep "Patch is empty." err &&
+	grep "To record the empty patch as an empty commit, run \"git am --allow-empty\"." err &&
+	git am --skip &&
+	test_path_is_missing .git/rebase-apply &&
+	git rev-parse empty-commit^ >expected &&
+	git rev-parse HEAD >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'record an empty patch as an empty commit in the middle of an am session' '
+	git checkout empty-commit^ &&
+	test_must_fail git am empty-commit.patch >err &&
+	grep "Patch is empty." err &&
+	grep "To record the empty patch as an empty commit, run \"git am --allow-empty\"." err &&
+	git am --allow-empty >output &&
+	grep "No changes - recorded it as an empty commit." output &&
+	test_path_is_missing .git/rebase-apply &&
+	git show empty-commit --format="%B" >expected &&
+	git show HEAD --format="%B" >actual &&
+	grep -f actual expected
+'
+
+test_expect_success 'create an non-empty commit when the index IS changed though "--allow-empty" is given' '
+	git checkout empty-commit^ &&
+	test_must_fail git am empty-commit.patch >err &&
+	: >empty-file &&
+	git add empty-file &&
+	git am --allow-empty &&
+	git show empty-commit --format="%B" >expected &&
+	git show HEAD --format="%B" >actual &&
+	grep -f actual expected &&
+	git diff HEAD^..HEAD --name-only
+'
+
+test_expect_success 'cannot create empty commits when there is a clean index due to merge conflicts' '
+	test_when_finished "git am --abort || :" &&
+	git rev-parse HEAD >expected &&
+	test_must_fail git am seq.patch &&
+	test_must_fail git am --allow-empty >err &&
+	! grep "To record the empty patch as an empty commit, run \"git am --allow-empty\"." err &&
+	git rev-parse HEAD >actual &&
+	test_cmp actual expected
+'
+
+test_expect_success 'cannot create empty commits when there is unmerged index due to merge conflicts' '
+	test_when_finished "git am --abort || :" &&
+	git rev-parse HEAD >expected &&
+	test_must_fail git am -3 seq.patch &&
+	test_must_fail git am --allow-empty >err &&
+	! grep "To record the empty patch as an empty commit, run \"git am --allow-empty\"." err &&
+	git rev-parse HEAD >actual &&
+	test_cmp actual expected
+'
+
 test_done
diff --git a/t/t4151-am-abort.sh b/t/t4151-am-abort.sh
index 2374151..5ed7e22 100755
--- a/t/t4151-am-abort.sh
+++ b/t/t4151-am-abort.sh
@@ -5,10 +5,7 @@
 . ./test-lib.sh
 
 test_expect_success setup '
-	for i in a b c d e f g
-	do
-		echo $i
-	done >file-1 &&
+	test_write_lines a b c d e f g >file-1 &&
 	cp file-1 file-2 &&
 	test_tick &&
 	git add file-1 file-2 &&
@@ -43,10 +40,7 @@
 
 		test_must_fail git am$with3 000[1245]-*.patch &&
 		git log --pretty=tformat:%s >actual &&
-		for i in 3 2 initial
-		do
-			echo $i
-		done >expect &&
+		test_write_lines 3 2 initial >expect &&
 		test_cmp expect actual
 	'
 
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 7884e3d..5049559 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -120,48 +120,48 @@
 
 test_expect_success 'diff-filter=M' '
 
-	actual=$(git log --pretty="format:%s" --diff-filter=M HEAD) &&
-	expect=$(echo second) &&
-	verbose test "$actual" = "$expect"
+	git log --pretty="format:%s" --diff-filter=M HEAD >actual &&
+	printf "second" >expect &&
+	test_cmp expect actual
 
 '
 
 test_expect_success 'diff-filter=D' '
 
-	actual=$(git log --no-renames --pretty="format:%s" --diff-filter=D HEAD) &&
-	expect=$(echo sixth ; echo third) &&
-	verbose test "$actual" = "$expect"
+	git log --no-renames --pretty="format:%s" --diff-filter=D HEAD >actual &&
+	printf "sixth\nthird" >expect &&
+	test_cmp expect actual
 
 '
 
 test_expect_success 'diff-filter=R' '
 
-	actual=$(git log -M --pretty="format:%s" --diff-filter=R HEAD) &&
-	expect=$(echo third) &&
-	verbose test "$actual" = "$expect"
+	git log -M --pretty="format:%s" --diff-filter=R HEAD >actual &&
+	printf "third" >expect &&
+	test_cmp expect actual
 
 '
 
 test_expect_success 'diff-filter=C' '
 
-	actual=$(git log -C -C --pretty="format:%s" --diff-filter=C HEAD) &&
-	expect=$(echo fourth) &&
-	verbose test "$actual" = "$expect"
+	git log -C -C --pretty="format:%s" --diff-filter=C HEAD >actual &&
+	printf "fourth" >expect &&
+	test_cmp expect actual
 
 '
 
 test_expect_success 'git log --follow' '
 
-	actual=$(git log --follow --pretty="format:%s" ichi) &&
-	expect=$(echo third ; echo second ; echo initial) &&
-	verbose test "$actual" = "$expect"
+	git log --follow --pretty="format:%s" ichi >actual &&
+	printf "third\nsecond\ninitial" >expect &&
+	test_cmp expect actual
 '
 
 test_expect_success 'git config log.follow works like --follow' '
 	test_config log.follow true &&
-	actual=$(git log --pretty="format:%s" ichi) &&
-	expect=$(echo third ; echo second ; echo initial) &&
-	verbose test "$actual" = "$expect"
+	git log --pretty="format:%s" ichi >actual &&
+	printf "third\nsecond\ninitial" >expect &&
+	test_cmp expect actual
 '
 
 test_expect_success 'git config log.follow does not die with multiple paths' '
@@ -176,9 +176,9 @@
 
 test_expect_success 'git config log.follow is overridden by --no-follow' '
 	test_config log.follow true &&
-	actual=$(git log --no-follow --pretty="format:%s" ichi) &&
-	expect="third" &&
-	verbose test "$actual" = "$expect"
+	git log --no-follow --pretty="format:%s" ichi >actual &&
+	printf "third" >expect &&
+	test_cmp expect actual
 '
 
 # Note that these commits are intentionally listed out of order.
@@ -250,7 +250,7 @@
 	test_cmp expect actual &&
 
 	# POSIX extended
-	git -c grep.patternType=basic log --pretty="tformat:%s" --invert-grep --grep=t[h] --grep=S[e]c >actual &&
+	git -c grep.patternType=extended log --pretty="tformat:%s" --invert-grep --grep=t[h] --grep=S[e]c >actual &&
 	test_cmp expect actual &&
 
 	# PCRE
@@ -952,6 +952,43 @@
 	test_cmp expect.decorate actual
 '
 
+test_expect_success 'decorate-refs with implied decorate from format' '
+	cat >expect <<-\EOF &&
+	side-2 (tag: side-2)
+	side-1
+	EOF
+	git log --no-walk --format="%s%d" \
+		--decorate-refs="*side-2" side-1 side-2 \
+		>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'implied decorate does not override option' '
+	cat >expect <<-\EOF &&
+	side-2 (tag: refs/tags/side-2, refs/heads/side)
+	side-1 (tag: refs/tags/side-1)
+	EOF
+	git log --no-walk --format="%s%d" \
+		--decorate=full side-1 side-2 \
+		>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'decorate-refs and simplify-by-decoration without output' '
+	cat >expect <<-\EOF &&
+	side-2
+	initial
+	EOF
+	# Do not just use a --format without %d here; we want to
+	# make sure that we did not accidentally turn on displaying
+	# the decorations, too. And that requires one of the regular
+	# formats.
+	git log --decorate-refs="*side-2" --oneline \
+		--simplify-by-decoration >actual.raw &&
+	sed "s/^[0-9a-f]* //" <actual.raw >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'log.decorate config parsing' '
 	git log --oneline --decorate=full >expect.full &&
 	git log --oneline --decorate=short >expect.short &&
@@ -1677,6 +1714,24 @@
 	git commit -S -m signed_commit
 '
 
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'create signed commits with keys having defined lifetimes' '
+	test_config gpg.format ssh &&
+	touch file &&
+	git add file &&
+
+	echo expired >file && test_tick && git commit -a -m expired -S"${GPGSSH_KEY_EXPIRED}" &&
+	git tag expired-signed &&
+
+	echo notyetvalid >file && test_tick && git commit -a -m notyetvalid -S"${GPGSSH_KEY_NOTYETVALID}" &&
+	git tag notyetvalid-signed &&
+
+	echo timeboxedvalid >file && test_tick && git commit -a -m timeboxedvalid -S"${GPGSSH_KEY_TIMEBOXEDVALID}" &&
+	git tag timeboxedvalid-signed &&
+
+	echo timeboxedinvalid >file && test_tick && git commit -a -m timeboxedinvalid -S"${GPGSSH_KEY_TIMEBOXEDINVALID}" &&
+	git tag timeboxedinvalid-signed
+'
+
 test_expect_success GPGSM 'log x509 fingerprint' '
 	echo "F8BF62E0693D0694816377099909C779FA23FD65 | " >expect &&
 	git log -n1 --format="%GF | %GP" signed-x509 >actual &&
@@ -1714,6 +1769,31 @@
 	grep "${GOOD_SIGNATURE_TRUSTED}" actual
 '
 
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'log shows failure on expired signature key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git log --graph --show-signature -n1 expired-signed >actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'log shows failure on not yet valid signature key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git log --graph --show-signature -n1 notyetvalid-signed >actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'log show success with commit date and key validity matching' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git log --graph --show-signature -n1 timeboxedvalid-signed >actual &&
+	grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual &&
+	! grep "${GPGSSH_BAD_SIGNATURE}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'log shows failure with commit date outside of key validity' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git log --graph --show-signature -n1 timeboxedinvalid-signed >actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
 test_expect_success GPG 'log --graph --show-signature for merged tag' '
 	test_when_finished "git reset --hard && git checkout main" &&
 	git checkout -b plain main &&
@@ -2010,4 +2090,23 @@
        test_cmp expect actual
 '
 
+test_expect_success 'set up commits with different authors' '
+	git checkout --orphan authors &&
+	test_commit --author "Jim <jim@example.com>" jim_1 &&
+	test_commit --author "Val <val@example.com>" val_1 &&
+	test_commit --author "Val <val@example.com>" val_2 &&
+	test_commit --author "Jim <jim@example.com>" jim_2 &&
+	test_commit --author "Val <val@example.com>" val_3 &&
+	test_commit --author "Jim <jim@example.com>" jim_3
+'
+
+test_expect_success 'log --invert-grep --grep --author' '
+	cat >expect <<-\EOF &&
+	val_3
+	val_1
+	EOF
+	git log --format=%s --author=Val --grep 2 --invert-grep >actual &&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/t/t4204-patch-id.sh b/t/t4204-patch-id.sh
index f120857..80f4a65 100755
--- a/t/t4204-patch-id.sh
+++ b/t/t4204-patch-id.sh
@@ -27,7 +27,8 @@
 '
 
 test_expect_success 'patch-id output is well-formed' '
-	git log -p -1 | git patch-id >output &&
+	git log -p -1 >log.output &&
+	git patch-id <log.output >output &&
 	grep "^$OID_REGEX $(git rev-parse HEAD)$" output
 '
 
@@ -35,8 +36,8 @@
 calc_patch_id () {
 	patch_name="$1"
 	shift
-	git patch-id "$@" |
-	sed "s/ .*//" >patch-id_"$patch_name" &&
+	git patch-id "$@" >patch-id.output &&
+	sed "s/ .*//" patch-id.output >patch-id_"$patch_name" &&
 	test_line_count -gt 0 patch-id_"$patch_name"
 }
 
@@ -45,7 +46,8 @@
 }
 
 get_patch_id () {
-	get_top_diff "$1" | calc_patch_id "$@"
+	get_top_diff "$1" >top-diff.output &&
+	calc_patch_id <top-diff.output "$@"
 }
 
 test_expect_success 'patch-id detects equality' '
@@ -63,16 +65,18 @@
 test_expect_success 'patch-id supports git-format-patch output' '
 	get_patch_id main &&
 	git checkout same &&
-	git format-patch -1 --stdout | calc_patch_id same &&
+	git format-patch -1 --stdout >format-patch.output &&
+	calc_patch_id same <format-patch.output &&
 	test_cmp patch-id_main patch-id_same &&
-	set $(git format-patch -1 --stdout | git patch-id) &&
+	set $(git patch-id <format-patch.output) &&
 	test "$2" = $(git rev-parse HEAD)
 '
 
 test_expect_success 'whitespace is irrelevant in footer' '
 	get_patch_id main &&
 	git checkout same &&
-	git format-patch -1 --stdout | sed "s/ \$//" | calc_patch_id same &&
+	git format-patch -1 --stdout >format-patch.output &&
+	sed "s/ \$//" format-patch.output | calc_patch_id same &&
 	test_cmp patch-id_main patch-id_same
 '
 
@@ -91,10 +95,11 @@
 	shift
 	name="order-${1}-$relevant"
 	shift
-	get_top_diff "main" | calc_patch_id "$name" "$@" &&
+	get_top_diff "main" >top-diff.output &&
+	calc_patch_id <top-diff.output "$name" "$@" &&
 	git checkout same &&
-	git format-patch -1 --stdout -O foo-then-bar |
-		calc_patch_id "ordered-$name" "$@" &&
+	git format-patch -1 --stdout -O foo-then-bar >format-patch.output &&
+	calc_patch_id <format-patch.output "ordered-$name" "$@" &&
 	cmp_patch_id $relevant "$name" "ordered-$name"
 
 }
@@ -142,7 +147,8 @@
 test_expect_success 'patch-id supports git-format-patch MIME output' '
 	get_patch_id main &&
 	git checkout same &&
-	git format-patch -1 --attach --stdout | calc_patch_id same &&
+	git format-patch -1 --attach --stdout >format-patch.output &&
+	calc_patch_id <format-patch.output same &&
 	test_cmp patch-id_main patch-id_same
 '
 
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 5865daa..e448ef2 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -976,7 +976,7 @@
 		else
 			: >expect-contains-bad
 		fi &&
-		echo "$hash $desc"
+		echo "$hash $desc" || return 1
 	done >expect &&
 	test_path_exists expect-contains-good &&
 	test_path_exists expect-contains-bad &&
@@ -1002,4 +1002,20 @@
 	test_cmp expect actual
 '
 
+test_expect_success '%(describe:tags) vs git describe --tags' '
+	test_when_finished "git tag -d tagname" &&
+	git tag tagname &&
+	git describe --tags >expect &&
+	git log -1 --format="%(describe:tags)" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(describe:abbrev=...) vs git describe --abbrev=...' '
+	test_when_finished "git tag -d tagname" &&
+	git tag -a -m tagged tagname &&
+	git describe --abbrev=15 >expect &&
+	git log -1 --format="%(describe:abbrev=15)" >actual &&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/t/t4209-log-pickaxe.sh b/t/t4209-log-pickaxe.sh
index 75795d0..7f6bb27 100755
--- a/t/t4209-log-pickaxe.sh
+++ b/t/t4209-log-pickaxe.sh
@@ -63,21 +63,21 @@
 	test_i18ngrep "switch.*requires a value" err &&
 
 	test_expect_code 128 git log -Gregex -Sstring 2>err &&
-	grep "mutually exclusive" err &&
+	grep "cannot be used together" err &&
 
 	test_expect_code 128 git log -Gregex --find-object=HEAD 2>err &&
-	grep "mutually exclusive" err &&
+	grep "cannot be used together" err &&
 
 	test_expect_code 128 git log -Sstring --find-object=HEAD 2>err &&
-	grep "mutually exclusive" err &&
+	grep "cannot be used together" err &&
 
 	test_expect_code 128 git log --pickaxe-all --find-object=HEAD 2>err &&
-	grep "mutually exclusive" err
+	grep "cannot be used together" err
 '
 
 test_expect_success 'usage: --pickaxe-regex' '
 	test_expect_code 128 git log -Gregex --pickaxe-regex 2>err &&
-	grep "mutually exclusive" err
+	grep "cannot be used together" err
 '
 
 test_expect_success 'usage: --no-pickaxe-regex' '
diff --git a/t/t4211-line-log.sh b/t/t4211-line-log.sh
index 560127c..ac9e4d0 100755
--- a/t/t4211-line-log.sh
+++ b/t/t4211-line-log.sh
@@ -137,7 +137,7 @@
 	test_seq 1000 > c.c &&
 	git add c.c &&
 	git commit -m "modify many lines" &&
-	git log $(for x in $(test_seq 200); do echo -L $((2*x)),+1:c.c; done)
+	git log $(for x in $(test_seq 200); do echo -L $((2*x)),+1:c.c || return 1; done)
 '
 
 test_expect_success '-s shows only line-log commits' '
diff --git a/t/t4212-log-corrupt.sh b/t/t4212-log-corrupt.sh
index 03b952c..0244888 100755
--- a/t/t4212-log-corrupt.sh
+++ b/t/t4212-log-corrupt.sh
@@ -20,10 +20,10 @@
 
 test_expect_success 'git log with broken author email' '
 	{
-		echo commit $(cat broken_email.hash)
-		echo "Author: A U Thor <author@example.com>"
-		echo "Date:   Thu Apr 7 15:13:13 2005 -0700"
-		echo
+		echo commit $(cat broken_email.hash) &&
+		echo "Author: A U Thor <author@example.com>" &&
+		echo "Date:   Thu Apr 7 15:13:13 2005 -0700" &&
+		echo &&
 		echo "    foo"
 	} >expect.out &&
 
diff --git a/t/t4216-log-bloom.sh b/t/t4216-log-bloom.sh
index 50f206d..cc3cebf 100755
--- a/t/t4216-log-bloom.sh
+++ b/t/t4216-log-bloom.sh
@@ -175,13 +175,11 @@
 	test_when_finished rm -rf .git/objects/info/commit-graph* &&
 	rm -rf .git/objects/info/commit-graph* &&
 	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
-		GIT_TRACE2_EVENT_NESTING=5 \
 		GIT_TEST_BLOOM_SETTINGS_NUM_HASHES=9 \
 		GIT_TEST_BLOOM_SETTINGS_BITS_PER_ENTRY=15 \
 		git commit-graph write --reachable --changed-paths &&
 	grep "{\"hash_version\":1,\"num_hashes\":9,\"bits_per_entry\":15,\"max_changed_paths\":512" trace2.txt &&
 	GIT_TRACE2_EVENT="$(pwd)/trace2-auto.txt" \
-		GIT_TRACE2_EVENT_NESTING=5 \
 		git commit-graph write --reachable --changed-paths &&
 	grep "{\"hash_version\":1,\"num_hashes\":9,\"bits_per_entry\":15,\"max_changed_paths\":512" trace2-auto.txt
 '
@@ -376,7 +374,7 @@
 		cd empty &&
 		for i in $(test_seq 1 6)
 		do
-			git commit --allow-empty -m "$i"
+			git commit --allow-empty -m "$i" || return 1
 		done &&
 
 		# Generate Bloom filters for empty commits 1-6, two at a time.
@@ -389,7 +387,7 @@
 			test_filter_computed 2 trace.event &&
 			test_filter_not_computed 4 trace.event &&
 			test_filter_trunc_empty 2 trace.event &&
-			test_filter_trunc_large 0 trace.event
+			test_filter_trunc_large 0 trace.event || return 1
 		done &&
 
 		# Finally, make sure that once all commits have filters, that
diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
index 2c88d1c..7f8d2ab 100755
--- a/t/t5000-tar-tree.sh
+++ b/t/t5000-tar-tree.sh
@@ -77,7 +77,7 @@
 					path=$(get_pax_header $header path) &&
 					if test -n "$path"
 					then
-						mv "$data" "$path"
+						mv "$data" "$path" || exit 1
 					fi
 				fi
 			done
@@ -133,7 +133,7 @@
 		for depth in 1 2 3 4 5
 		do
 			mkdir $p &&
-			cd $p
+			cd $p || exit 1
 		done &&
 		echo text >file_with_long_path
 	) &&
diff --git a/t/t5002-archive-attr-pattern.sh b/t/t5002-archive-attr-pattern.sh
index bda6d7d..a66b5ba 100755
--- a/t/t5002-archive-attr-pattern.sh
+++ b/t/t5002-archive-attr-pattern.sh
@@ -2,6 +2,7 @@
 
 test_description='git archive attribute pattern tests'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_exists() {
diff --git a/t/t5003-archive-zip.sh b/t/t5003-archive-zip.sh
index 1e6d18b..d726964 100755
--- a/t/t5003-archive-zip.sh
+++ b/t/t5003-archive-zip.sh
@@ -106,7 +106,7 @@
      printf "A\$Format:%s\$O" "$SUBSTFORMAT" >a/substfile1 &&
      printf "A not substituted O" >a/substfile2 &&
      (p=long_path_to_a_file && cd a &&
-      for depth in 1 2 3 4 5; do mkdir $p && cd $p; done &&
+      for depth in 1 2 3 4 5; do mkdir $p && cd $p || exit 1; done &&
       echo text >file_with_long_path)
 '
 
diff --git a/t/t5004-archive-corner-cases.sh b/t/t5004-archive-corner-cases.sh
index 2d32d0e..ae508e2 100755
--- a/t/t5004-archive-corner-cases.sh
+++ b/t/t5004-archive-corner-cases.sh
@@ -131,7 +131,7 @@
 	do
 		for b in 0 1 2 3 4 5 6 7 8 9 a b c d e f
 		do
-			: >00/$a$b
+			: >00/$a$b || return 1
 		done
 	done &&
 	git add 00 &&
@@ -143,7 +143,7 @@
 	do
 		for d in 0 1 2 3 4 5 6 7 8 9 a b c d e f
 		do
-			echo "040000 tree $subtree	$c$d"
+			echo "040000 tree $subtree	$c$d" || return 1
 		done
 	done >tree &&
 	tree=$(git mktree <tree) &&
@@ -171,7 +171,7 @@
 	# create tree containing 65500 entries of that blob
 	for i in $(test_seq 1 65500)
 	do
-		echo "100644 blob $blob	$i"
+		echo "100644 blob $blob	$i" || return 1
 	done >tree &&
 	tree=$(git mktree <tree) &&
 
diff --git a/t/t5100-mailinfo.sh b/t/t5100-mailinfo.sh
index 141b29f..cebad10 100755
--- a/t/t5100-mailinfo.sh
+++ b/t/t5100-mailinfo.sh
@@ -122,7 +122,7 @@
 	do
 		git mailinfo mboxrd/msg mboxrd/patch \
 		  <mboxrd/$i >mboxrd/out &&
-		test_cmp "$DATA/${i}mboxrd" mboxrd/msg
+		test_cmp "$DATA/${i}mboxrd" mboxrd/msg || return 1
 	done &&
 	sp=" " &&
 	echo "From " >expect &&
diff --git a/t/t5200-update-server-info.sh b/t/t5200-update-server-info.sh
index 21a58ee..ed9dfd6 100755
--- a/t/t5200-update-server-info.sh
+++ b/t/t5200-update-server-info.sh
@@ -2,6 +2,7 @@
 
 test_description='Test git update-server-info'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' 'test_commit file'
diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index e13a884..2fd8451 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -347,7 +347,7 @@
 		for i in 0 1 2 3 4 5 6 7 8 9
 		do
 			o=$(echo $j$i | git hash-object -w --stdin) &&
-			echo "100644 $o	0 $j$i"
+			echo "100644 $o	0 $j$i" || return 1
 		done
 	done >LIST &&
 	rm -f .git/index &&
@@ -361,11 +361,7 @@
 	ST=$(git write-tree) &&
 	git rev-list --objects "$LIST" "$LI" "$ST" >actual &&
 	PACK5=$( git pack-objects test-5 <actual ) &&
-	PACK6=$( (
-			echo "$LIST"
-			echo "$LI"
-			echo "$ST"
-		 ) | git pack-objects test-6 ) &&
+	PACK6=$( test_write_lines "$LIST" "$LI" "$ST" | git pack-objects test-6 ) &&
 	test_create_repo test-5 &&
 	(
 		cd test-5 &&
@@ -394,7 +390,7 @@
 		for i in 0 1 2 3 4 5 6 7 8 9
 		do
 			o=$(echo $j$i | git hash-object -w --stdin) &&
-			echo "100644 $o	0 $j$i"
+			echo "100644 $o	0 $j$i" || return 1
 		done
 	done >LIST &&
 	rm -f .git/index &&
@@ -408,11 +404,7 @@
 	ST=$(git write-tree) &&
 	git rev-list --objects "$LIST" "$LI" "$ST" >actual &&
 	PACK5=$( git pack-objects test-5 <actual ) &&
-	PACK6=$( (
-			echo "$LIST"
-			echo "$LI"
-			echo "$ST"
-		 ) | git pack-objects test-6 ) &&
+	PACK6=$( test_write_lines "$LIST" "$LI" "$ST" | git pack-objects test-6 ) &&
 	test_create_repo test-7 &&
 	(
 		cd test-7 &&
@@ -594,7 +586,7 @@
 		for id in A B C
 		do
 			git pack-objects .git/objects/pack/pack-$id \
-				--incremental --revs <<-EOF
+				--incremental --revs <<-EOF || exit 1
 			refs/tags/$id
 			EOF
 		done &&
diff --git a/t/t5302-pack-index.sh b/t/t5302-pack-index.sh
index 7c9d687..8ee67df 100755
--- a/t/t5302-pack-index.sh
+++ b/t/t5302-pack-index.sh
@@ -14,7 +14,7 @@
 	i=1 &&
 	while test $i -le 100
 	do
-		iii=$(printf "%03i" $i)
+		iii=$(printf "%03i" $i) &&
 		test-tool genrandom "bar" 200 > wide_delta_$iii &&
 		test-tool genrandom "baz $iii" 50 >> wide_delta_$iii &&
 		test-tool genrandom "foo"$i 100 > deep_delta_$iii &&
diff --git a/t/t5306-pack-nobase.sh b/t/t5306-pack-nobase.sh
index f4931c0..51973f4 100755
--- a/t/t5306-pack-nobase.sh
+++ b/t/t5306-pack-nobase.sh
@@ -12,7 +12,7 @@
 #
 test_expect_success \
     'setup base' \
-    'for a in a b c d e f g h i; do echo $a >>text; done &&
+    'test_write_lines a b c d e f g h i >text &&
      echo side >side &&
      git update-index --add text side &&
      A=$(echo A | git commit-tree $(git write-tree)) &&
diff --git a/t/t5307-pack-missing-commit.sh b/t/t5307-pack-missing-commit.sh
index f4338ab..1e02c30 100755
--- a/t/t5307-pack-missing-commit.sh
+++ b/t/t5307-pack-missing-commit.sh
@@ -2,6 +2,7 @@
 
 test_description='pack should notice missing commit objects'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
@@ -11,7 +12,7 @@
 		git add "file$i" &&
 		test_tick &&
 		git commit -m "$i" &&
-		git tag "tag$i"
+		git tag "tag$i" || return 1
 	done &&
 	obj=$(git rev-parse --verify tag3) &&
 	fanout=$(expr "$obj" : "\(..\)") &&
diff --git a/t/t5310-pack-bitmaps.sh b/t/t5310-pack-bitmaps.sh
index dcf03d3..d05ab71 100755
--- a/t/t5310-pack-bitmaps.sh
+++ b/t/t5310-pack-bitmaps.sh
@@ -1,8 +1,6 @@
 #!/bin/sh
 
 test_description='exercise basic bitmap functionality'
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-bitmap.sh
@@ -35,7 +33,7 @@
 '
 
 test_expect_success 'full repack creates bitmaps' '
-	GIT_TRACE2_EVENT_NESTING=4 GIT_TRACE2_EVENT="$(pwd)/trace" \
+	GIT_TRACE2_EVENT="$(pwd)/trace" \
 		git repack -ad &&
 	ls .git/objects/pack/ | grep bitmap >output &&
 	test_line_count = 1 output &&
@@ -230,7 +228,7 @@
 	test_when_finished "rm -f .git/objects/pack/*.keep" &&
 	for i in .git/objects/pack/*.pack
 	do
-		>${i%.pack}.keep
+		>${i%.pack}.keep || return 1
 	done &&
 	reusable_pack --honor-pack-keep >empty.pack &&
 	git index-pack empty.pack &&
diff --git a/t/t5316-pack-delta-depth.sh b/t/t5316-pack-delta-depth.sh
index 759169d..df524f7 100755
--- a/t/t5316-pack-delta-depth.sh
+++ b/t/t5316-pack-delta-depth.sh
@@ -57,8 +57,11 @@
 		git commit -m $i &&
 		cur=$(git rev-parse HEAD^{tree}) &&
 		{
-			test -n "$prev" && echo "-$prev"
-			echo $cur
+			if test -n "$prev"
+			then
+				echo "-$prev"
+			fi &&
+			echo $cur &&
 			echo "$(git rev-parse :file) file"
 		} | git pack-objects --stdout >tmp &&
 		git index-pack --stdin --fix-thin <tmp || return 1
diff --git a/t/t5317-pack-objects-filter-objects.sh b/t/t5317-pack-objects-filter-objects.sh
index 13ed3eb..33b740ce 100755
--- a/t/t5317-pack-objects-filter-objects.sh
+++ b/t/t5317-pack-objects-filter-objects.sh
@@ -16,9 +16,9 @@
 	git init r1 &&
 	for n in 1 2 3 4 5
 	do
-		echo "This is file: $n" > r1/file.$n
-		git -C r1 add file.$n
-		git -C r1 commit -m "$n"
+		echo "This is file: $n" > r1/file.$n &&
+		git -C r1 add file.$n &&
+		git -C r1 commit -m "$n" || return 1
 	done
 '
 
@@ -116,9 +116,9 @@
 	git init r2 &&
 	for n in 1000 10000
 	do
-		printf "%"$n"s" X > r2/large.$n
-		git -C r2 add large.$n
-		git -C r2 commit -m "$n"
+		printf "%"$n"s" X > r2/large.$n &&
+		git -C r2 add large.$n &&
+		git -C r2 commit -m "$n" || return 1
 	done
 '
 
@@ -278,10 +278,10 @@
 	mkdir r3/dir1 &&
 	for n in sparse1 sparse2
 	do
-		echo "This is file: $n" > r3/$n
-		git -C r3 add $n
-		echo "This is file: dir1/$n" > r3/dir1/$n
-		git -C r3 add dir1/$n
+		echo "This is file: $n" > r3/$n &&
+		git -C r3 add $n &&
+		echo "This is file: dir1/$n" > r3/dir1/$n &&
+		git -C r3 add dir1/$n || return 1
 	done &&
 	git -C r3 commit -m "sparse" &&
 	echo dir1/ >pattern1 &&
@@ -331,10 +331,10 @@
 	mkdir r4/dir1 &&
 	for n in sparse1 sparse2
 	do
-		echo "This is file: $n" > r4/$n
-		git -C r4 add $n
-		echo "This is file: dir1/$n" > r4/dir1/$n
-		git -C r4 add dir1/$n
+		echo "This is file: $n" > r4/$n &&
+		git -C r4 add $n &&
+		echo "This is file: dir1/$n" > r4/dir1/$n &&
+		git -C r4 add dir1/$n || return 1
 	done &&
 	echo dir1/ >r4/pattern &&
 	git -C r4 add pattern &&
@@ -409,7 +409,7 @@
 
 	for id in `cat expected | sed "s|..|&/|"`
 	do
-		rm r1/.git/objects/$id
+		rm r1/.git/objects/$id || return 1
 	done
 '
 
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index f516fda..edb728f 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -64,7 +64,7 @@
 	for i in $(test_seq 3)
 	do
 		test_commit $i &&
-		git branch commits/$i
+		git branch commits/$i || return 1
 	done &&
 	git repack
 '
@@ -147,13 +147,13 @@
 	for i in $(test_seq 4 5)
 	do
 		test_commit $i &&
-		git branch commits/$i
+		git branch commits/$i || return 1
 	done &&
 	git reset --hard commits/2 &&
 	for i in $(test_seq 6 7)
 	do
 		test_commit $i &&
-		git branch commits/$i
+		git branch commits/$i || return 1
 	done &&
 	git reset --hard commits/2 &&
 	git merge commits/4 &&
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 3f69e43..afbe93f 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -93,7 +93,7 @@
 	test_commit initial &&
 	for i in $(test_seq 1 5)
 	do
-		generate_objects $i
+		generate_objects $i || return 1
 	done &&
 	commit_and_list_objects
 '
@@ -155,7 +155,7 @@
 test_expect_success 'add more objects' '
 	for i in $(test_seq 6 10)
 	do
-		generate_objects $i
+		generate_objects $i || return 1
 	done &&
 	commit_and_list_objects
 '
@@ -203,7 +203,7 @@
 	do
 		generate_objects $j &&
 		commit_and_list_objects &&
-		git pack-objects --index-version=2 $objdir/pack/test-pack <obj-list
+		git pack-objects --index-version=2 $objdir/pack/test-pack <obj-list || return 1
 	done
 '
 
@@ -482,8 +482,10 @@
 '
 
 test_expect_success 'verify incorrect checksum' '
-	pos=$(($(wc -c <$objdir/pack/multi-pack-index) - 1)) &&
-	corrupt_midx_and_verify $pos "\377" $objdir "incorrect checksum"
+	pos=$(($(wc -c <$objdir/pack/multi-pack-index) - 10)) &&
+	corrupt_midx_and_verify $pos \
+		"\377\377\377\377\377\377\377\377\377\377" \
+		$objdir "incorrect checksum"
 '
 
 test_expect_success 'repack progress off for redirected stderr' '
@@ -594,7 +596,7 @@
 	mkdir objects64/pack &&
 	for i in $(test_seq 1 11)
 	do
-		generate_objects 11
+		generate_objects 11 || return 1
 	done &&
 	commit_and_list_objects &&
 	pack64=$(git pack-objects --index-version=2,0x40 objects64/pack/test-64 <obj-list) &&
@@ -638,7 +640,7 @@
 		git update-index --add large_file.txt &&
 		for i in $(test_seq 1 20)
 		do
-			test_commit $i
+			test_commit $i || exit 1
 		done &&
 		git branch A HEAD &&
 		git branch B HEAD~8 &&
diff --git a/t/t5322-pack-objects-sparse.sh b/t/t5322-pack-objects-sparse.sh
index 61cb907..d39958c 100755
--- a/t/t5322-pack-objects-sparse.sh
+++ b/t/t5322-pack-objects-sparse.sh
@@ -14,7 +14,7 @@
 		for j in $(test_seq 1 3)
 		do
 			mkdir f$i/f$j &&
-			echo $j >f$i/f$j/data.txt
+			echo $j >f$i/f$j/data.txt || return 1
 		done
 	done &&
 	git add . &&
@@ -23,7 +23,7 @@
 	do
 		git checkout -b topic$i main &&
 		echo change-$i >f$i/f$i/data.txt &&
-		git commit -a -m "Changed f$i/f$i/data.txt"
+		git commit -a -m "Changed f$i/f$i/data.txt" || return 1
 	done &&
 	cat >packinput.txt <<-EOF &&
 	topic1
diff --git a/t/t5325-reverse-index.sh b/t/t5325-reverse-index.sh
index da453f6..d042d26 100755
--- a/t/t5325-reverse-index.sh
+++ b/t/t5325-reverse-index.sh
@@ -46,7 +46,7 @@
 		test_path_exists $rev &&
 
 		test_index_pack "$conf" --no-rev-index &&
-		test_path_is_missing $rev
+		test_path_is_missing $rev || return 1
 	done
 '
 
diff --git a/t/t5410-receive-pack-alternates.sh b/t/t5410-receive-pack-alternates.sh
index 0b28e4e..7a45d4c 100755
--- a/t/t5410-receive-pack-alternates.sh
+++ b/t/t5410-receive-pack-alternates.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t5500-fetch-pack.sh b/t/t5500-fetch-pack.sh
index 8a5d349..f0dc4e6 100755
--- a/t/t5500-fetch-pack.sh
+++ b/t/t5500-fetch-pack.sh
@@ -95,7 +95,7 @@
 	while [ $cur -le 10 ]; do
 		add A$cur $(eval echo \$A$prev) &&
 		prev=$cur &&
-		cur=$(($cur+1))
+		cur=$(($cur+1)) || return 1
 	done &&
 	add B1 $A1 &&
 	git update-ref refs/heads/A "$ATIP" &&
@@ -112,7 +112,7 @@
 	while [ $cur -le 65 ]; do
 		add B$cur $(eval echo \$B$prev) &&
 		prev=$cur &&
-		cur=$(($cur+1))
+		cur=$(($cur+1)) || return 1
 	done
 '
 
@@ -464,11 +464,11 @@
 test_expect_success 'setup tests for the --stdin parameter' '
 	for head in C D E F
 	do
-		add $head
+		add $head || return 1
 	done &&
 	for head in A B C D E F
 	do
-		git tag $head $head
+		git tag $head $head || return 1
 	done &&
 	cat >input <<-\EOF &&
 	refs/heads/C
diff --git a/t/t5502-quickfetch.sh b/t/t5502-quickfetch.sh
index 8c05c77..b160f8b 100755
--- a/t/t5502-quickfetch.sh
+++ b/t/t5502-quickfetch.sh
@@ -130,7 +130,7 @@
 	for i in 0 1 2 3 4 5 6 7 8 9; do
 		for j in 0 1 2 3 4 5 6 7 8 9; do
 			for k in 0 1 2 3 4 5 6 7 8 9; do
-				echo "$branchprefix$i$j$k" >> .git/packed-refs
+				echo "$branchprefix$i$j$k" >> .git/packed-refs || return 1
 			done
 		done
 	done &&
diff --git a/t/t5504-fetch-receive-strict.sh b/t/t5504-fetch-receive-strict.sh
index 6e5a9c2..b0b795a 100755
--- a/t/t5504-fetch-receive-strict.sh
+++ b/t/t5504-fetch-receive-strict.sh
@@ -292,7 +292,7 @@
 		receive.fsck.missingEmail warn &&
 	git push --porcelain dst bogus >act 2>&1 &&
 	grep "missingEmail" act &&
-	test_i18ngrep "Skipping unknown msg id.*whatever" act &&
+	test_i18ngrep "skipping unknown msg id.*whatever" act &&
 	git --git-dir=dst/.git branch -D bogus &&
 	git --git-dir=dst/.git config --add \
 		receive.fsck.missingEmail ignore &&
diff --git a/t/t5505-remote.sh b/t/t5505-remote.sh
index e6e3c8f..9ab3154 100755
--- a/t/t5505-remote.sh
+++ b/t/t5505-remote.sh
@@ -2,9 +2,6 @@
 
 test_description='git remote porcelain-ish'
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 
 setup_repository () {
@@ -1332,7 +1329,6 @@
 	(
 		cd test &&
 		git tag -a -m "Some tag" some-tag main &&
-		exit_with=true &&
 		for type in commit tag tree blob
 		do
 			if test "$type" = "blob"
@@ -1348,9 +1344,8 @@
 				push origin $oid:dst 2>err &&
 			test_i18ngrep "error: The destination you" err &&
 			test_i18ngrep ! "hint: Did you mean" err ||
-			exit_with=false
-		done &&
-		$exit_with
+			exit 1
+		done
 	)
 '
 
diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh
index a0faf0d..20f7110 100755
--- a/t/t5510-fetch.sh
+++ b/t/t5510-fetch.sh
@@ -5,9 +5,6 @@
 
 '
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-bundle.sh
 
@@ -40,11 +37,11 @@
 		git config branch.main.remote two &&
 		git config branch.main.merge refs/heads/one &&
 		mkdir -p .git/remotes &&
-		{
-			echo "URL: ../two/.git/"
-			echo "Pull: refs/heads/main:refs/heads/two"
-			echo "Pull: refs/heads/one:refs/heads/one"
-		} >.git/remotes/two
+		cat >.git/remotes/two <<-\EOF
+		URL: ../two/.git/
+		Pull: refs/heads/main:refs/heads/two
+		Pull: refs/heads/one:refs/heads/one
+		EOF
 	) &&
 	git clone . bundle &&
 	git clone . seven
@@ -71,7 +68,7 @@
 	main_in_two=$(cd ../two && git rev-parse main) &&
 	one_in_two=$(cd ../two && git rev-parse one) &&
 	{
-		echo "$one_in_two	"
+		echo "$one_in_two	" &&
 		echo "$main_in_two	not-for-merge"
 	} >expected &&
 	cut -f -2 .git/FETCH_HEAD >actual &&
@@ -550,7 +547,7 @@
 	git bundle list-heads bundle5 >actual &&
 	for h in HEAD refs/heads/main
 	do
-		echo "$(git rev-parse --verify $h) $h"
+		echo "$(git rev-parse --verify $h) $h" || return 1
 	done >expect &&
 	test_cmp expect actual
 
diff --git a/t/t5515-fetch-merge-logic.sh b/t/t5515-fetch-merge-logic.sh
index 50f1410..320d267 100755
--- a/t/t5515-fetch-merge-logic.sh
+++ b/t/t5515-fetch-merge-logic.sh
@@ -105,19 +105,19 @@
 	remotes="$remotes config-glob" &&
 
 	mkdir -p .git/remotes &&
-	{
-		echo "URL: ../.git/"
-		echo "Pull: refs/heads/main:remotes/rem/main"
-		echo "Pull: refs/heads/one:remotes/rem/one"
-		echo "Pull: two:remotes/rem/two"
-		echo "Pull: refs/heads/three:remotes/rem/three"
-	} >.git/remotes/remote-explicit &&
+	cat >.git/remotes/remote-explicit <<-\EOF &&
+	URL: ../.git/
+	Pull: refs/heads/main:remotes/rem/main
+	Pull: refs/heads/one:remotes/rem/one
+	Pull: two:remotes/rem/two
+	Pull: refs/heads/three:remotes/rem/three
+	EOF
 	remotes="$remotes remote-explicit" &&
 
-	{
-		echo "URL: ../.git/"
-		echo "Pull: refs/heads/*:refs/remotes/rem/*"
-	} >.git/remotes/remote-glob &&
+	cat >.git/remotes/remote-glob <<-\EOF &&
+	URL: ../.git/
+	Pull: refs/heads/*:refs/remotes/rem/*
+	EOF
 	remotes="$remotes remote-glob" &&
 
 	mkdir -p .git/branches &&
@@ -133,7 +133,7 @@
 		git config branch.br-$remote-merge.merge refs/heads/three &&
 		git config branch.br-$remote-octopus.remote $remote &&
 		git config branch.br-$remote-octopus.merge refs/heads/one &&
-		git config --add branch.br-$remote-octopus.merge two
+		git config --add branch.br-$remote-octopus.merge two || return 1
 	done &&
 	build_script sed_script
 '
@@ -191,17 +191,17 @@
 		cp "$expect_r" expect_r &&
 		convert_expected expect_r sed_script &&
 		{
-			echo "# $cmd"
-			set x $cmd; shift
-			git symbolic-ref HEAD refs/heads/$1 ; shift
-			rm -f .git/FETCH_HEAD
+			echo "# $cmd" &&
+			set x $cmd && shift &&
+			git symbolic-ref HEAD refs/heads/$1 && shift &&
+			rm -f .git/FETCH_HEAD &&
 			git for-each-ref \
 				refs/heads refs/remotes/rem refs/tags |
 			while read val type refname
 			do
-				git update-ref -d "$refname" "$val"
-			done
-			git fetch "$@" >/dev/null
+				git update-ref -d "$refname" "$val" || return 1
+			done &&
+			git fetch "$@" >/dev/null &&
 			cat .git/FETCH_HEAD
 		} >"$actual_f" &&
 		git show-ref >"$actual_r" &&
diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh
index 8212ca5..2f04cf9 100755
--- a/t/t5516-fetch-push.sh
+++ b/t/t5516-fetch-push.sh
@@ -541,6 +541,15 @@
 
 done
 
+test_expect_success "push to remote with no explicit refspec and config remote.*.push = src:dest" '
+	mk_test testrepo heads/main &&
+	git checkout $the_first_commit &&
+	test_config remote.there.url testrepo &&
+	test_config remote.there.push refs/heads/main:refs/heads/main &&
+	git push there &&
+	check_push_result testrepo $the_commit heads/main
+'
+
 test_expect_success 'push with remote.pushdefault' '
 	mk_test up_repo heads/main &&
 	mk_test down_repo heads/main &&
@@ -1316,10 +1325,7 @@
 		git pull ../testrepo main &&
 		git tag -m "annotated" tag &&
 		git for-each-ref >tmp1 &&
-		(
-			cat tmp1
-			sed -n "s|refs/heads/main$|refs/remotes/origin/main|p" tmp1
-		) |
+		sed -n "p; s|refs/heads/main$|refs/remotes/origin/main|p" tmp1 |
 		sort -k 3 >../expect
 	) &&
 	git init dst &&
@@ -1769,6 +1775,38 @@
 	test_must_fail git -C cloned push origin HEAD:new-wt &&
 	test_config receive.denyCurrentBranch updateInstead &&
 	git -C cloned push origin HEAD:new-wt &&
+	test_path_exists new-wt/first.t &&
 	test_must_fail git -C cloned push --delete origin new-wt
 '
+
+test_expect_success 'denyCurrentBranch and bare repository worktrees' '
+	test_when_finished "rm -fr bare.git" &&
+	git clone --bare . bare.git &&
+	git -C bare.git worktree add wt &&
+	test_commit grape &&
+	git -C bare.git config receive.denyCurrentBranch refuse &&
+	test_must_fail git push bare.git HEAD:wt &&
+	git -C bare.git config receive.denyCurrentBranch updateInstead &&
+	git push bare.git HEAD:wt &&
+	test_path_exists bare.git/wt/grape.t &&
+	test_must_fail git push --delete bare.git wt
+'
+
+test_expect_success 'refuse fetch to current branch of worktree' '
+	test_when_finished "git worktree remove --force wt && git branch -D wt" &&
+	git worktree add wt &&
+	test_commit apple &&
+	test_must_fail git fetch . HEAD:wt &&
+	git fetch -u . HEAD:wt
+'
+
+test_expect_success 'refuse fetch to current branch of bare repository worktree' '
+	test_when_finished "rm -fr bare.git" &&
+	git clone --bare . bare.git &&
+	git -C bare.git worktree add wt &&
+	test_commit banana &&
+	test_must_fail git -C bare.git fetch .. HEAD:wt &&
+	git -C bare.git fetch -u .. HEAD:wt
+'
+
 test_done
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 2dc75b8..840c89c 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -3,9 +3,6 @@
 
 test_description='Recursive "git fetch" for submodules'
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 GIT_TEST_FATAL_REGISTER_SUBMODULE_ODB=1
 export GIT_TEST_FATAL_REGISTER_SUBMODULE_ODB
 
diff --git a/t/t5540-http-push-webdav.sh b/t/t5540-http-push-webdav.sh
index 8b68bb3..b0dbacf 100755
--- a/t/t5540-http-push-webdav.sh
+++ b/t/t5540-http-push-webdav.sh
@@ -18,6 +18,12 @@
 	test_done
 fi
 
+if test_have_prereq !REFFILES
+then
+	skip_all='skipping test; dumb HTTP protocol not supported with reftable.'
+	test_done
+fi
+
 LIB_HTTPD_DAV=t
 . "$TEST_DIRECTORY"/lib-httpd.sh
 ROOT_PATH="$PWD"
diff --git a/t/t5550-http-fetch-dumb.sh b/t/t5550-http-fetch-dumb.sh
index 6d9142a..2592039 100755
--- a/t/t5550-http-fetch-dumb.sh
+++ b/t/t5550-http-fetch-dumb.sh
@@ -5,6 +5,13 @@
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 . ./test-lib.sh
+
+if test_have_prereq !REFFILES
+then
+	skip_all='skipping test; dumb HTTP protocol not supported with reftable.'
+	test_done
+fi
+
 . "$TEST_DIRECTORY"/lib-httpd.sh
 start_httpd
 
diff --git a/t/t5552-skipping-fetch-negotiator.sh b/t/t5552-skipping-fetch-negotiator.sh
index 7b9fb4f..165427d 100755
--- a/t/t5552-skipping-fetch-negotiator.sh
+++ b/t/t5552-skipping-fetch-negotiator.sh
@@ -48,7 +48,7 @@
 	git init client &&
 	for i in $(test_seq 7)
 	do
-		test_commit -C client c$i
+		test_commit -C client c$i || return 1
 	done &&
 
 	# We send: "c7" (skip 1) "c5" (skip 2) "c2" (skip 4). After that, since
@@ -68,7 +68,7 @@
 	git init client &&
 	for i in $(test_seq 11)
 	do
-		test_commit -C client c$i
+		test_commit -C client c$i || return 1
 	done &&
 	git -C client checkout c5 &&
 	test_commit -C client c5side &&
@@ -155,14 +155,14 @@
 	for i in $(test_seq 8)
 	do
 		git -C client checkout --orphan b$i &&
-		test_commit -C client b$i.c0
+		test_commit -C client b$i.c0 || return 1
 	done &&
 	for j in $(test_seq 19)
 	do
 		for i in $(test_seq 8)
 		do
 			git -C client checkout b$i &&
-			test_commit -C client b$i.c$j
+			test_commit -C client b$i.c$j || return 1
 		done
 	done &&
 
@@ -201,7 +201,7 @@
 	# should still send the others (in this test, just check b2).
 	for i in $(test_seq 0 8)
 	do
-		have_not_sent b1.c$i
+		have_not_sent b1.c$i || return 1
 	done &&
 	have_sent b2.c1 b2.c0
 '
diff --git a/t/t5553-set-upstream.sh b/t/t5553-set-upstream.sh
index 9c12c0f..4805016 100755
--- a/t/t5553-set-upstream.sh
+++ b/t/t5553-set-upstream.sh
@@ -91,6 +91,17 @@
 	check_config_missing other2
 '
 
+test_expect_success 'fetch --set-upstream with a detached HEAD' '
+	git checkout HEAD^0 &&
+	test_when_finished "git checkout -" &&
+	cat >expect <<-\EOF &&
+	warning: could not set upstream of HEAD to '"'"'main'"'"' from '"'"'upstream'"'"' when it does not point to any branch.
+	EOF
+	git fetch --set-upstream upstream main 2>actual.raw &&
+	grep ^warning: actual.raw >actual &&
+	test_cmp expect actual
+'
+
 # tests for pull --set-upstream
 
 test_expect_success 'setup bare parent pull' '
@@ -178,4 +189,15 @@
 	check_config_missing other2
 '
 
+test_expect_success 'pull --set-upstream with a detached HEAD' '
+	git checkout HEAD^0 &&
+	test_when_finished "git checkout -" &&
+	cat >expect <<-\EOF &&
+	warning: could not set upstream of HEAD to '"'"'main'"'"' from '"'"'upstream'"'"' when it does not point to any branch.
+	EOF
+	git pull --no-rebase --set-upstream upstream main 2>actual.raw &&
+	grep ^warning: actual.raw >actual &&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/t/t5555-http-smart-common.sh b/t/t5555-http-smart-common.sh
index 49faf5e..b1cfe8b 100755
--- a/t/t5555-http-smart-common.sh
+++ b/t/t5555-http-smart-common.sh
@@ -2,6 +2,7 @@
 
 test_description='test functionality common to smart fetch & push'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t5562-http-backend-content-length.sh b/t/t5562-http-backend-content-length.sh
index 05a5806..b68ec22 100755
--- a/t/t5562-http-backend-content-length.sh
+++ b/t/t5562-http-backend-content-length.sh
@@ -63,7 +63,7 @@
 	hash_next=$(git commit-tree -p HEAD -m next HEAD^{tree}) &&
 	{
 		printf "%s %s refs/heads/newbranch\\0report-status object-format=%s\\n" \
-			"$ZERO_OID" "$hash_next" "$(test_oid algo)" | packetize_raw
+			"$ZERO_OID" "$hash_next" "$(test_oid algo)" | packetize_raw &&
 		printf 0000 &&
 		echo "$hash_next" | git pack-objects --stdout
 	} >push_body &&
diff --git a/t/t5570-git-daemon.sh b/t/t5570-git-daemon.sh
index b87ca06..1131503 100755
--- a/t/t5570-git-daemon.sh
+++ b/t/t5570-git-daemon.sh
@@ -194,7 +194,7 @@
 
 test_expect_success FAKENC 'hostname interpolation works after LF-stripping' '
 	{
-		printf "git-upload-pack /interp.git\n\0host=localhost" | packetize_raw
+		printf "git-upload-pack /interp.git\n\0host=localhost" | packetize_raw &&
 		printf "0000"
 	} >input &&
 	fake_nc "$GIT_DAEMON_HOST_PORT" <input >output &&
diff --git a/t/t5571-pre-push-hook.sh b/t/t5571-pre-push-hook.sh
index ad8d580..660f876 100755
--- a/t/t5571-pre-push-hook.sh
+++ b/t/t5571-pre-push-hook.sh
@@ -114,11 +114,11 @@
 
 test_expect_success 'set up many-ref tests' '
 	{
-		nr=1000
+		nr=1000 &&
 		while test $nr -lt 2000
 		do
-			nr=$(( $nr + 1 ))
-			echo "create refs/heads/b/$nr $COMMIT3"
+			nr=$(( $nr + 1 )) &&
+			echo "create refs/heads/b/$nr $COMMIT3" || return 1
 		done
 	} | git update-ref --stdin
 '
diff --git a/t/t5602-clone-remote-exec.sh b/t/t5602-clone-remote-exec.sh
index cbcceab..56329aa 100755
--- a/t/t5602-clone-remote-exec.sh
+++ b/t/t5602-clone-remote-exec.sh
@@ -2,6 +2,7 @@
 
 test_description=clone
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
diff --git a/t/t5603-clone-dirname.sh b/t/t5603-clone-dirname.sh
index 13b5e5e..8ca1f09 100755
--- a/t/t5603-clone-dirname.sh
+++ b/t/t5603-clone-dirname.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='check output directory names used by git-clone'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # we use a fake ssh wrapper that ignores the arguments
diff --git a/t/t5606-clone-options.sh b/t/t5606-clone-options.sh
index d822153..8f676d6 100755
--- a/t/t5606-clone-options.sh
+++ b/t/t5606-clone-options.sh
@@ -46,7 +46,7 @@
 
 	test_must_fail git clone -o foo --bare parent clone-bare-o 2>err &&
 	test_debug "cat err" &&
-	test_i18ngrep -e "--bare and --origin foo options are incompatible" err
+	test_i18ngrep -e "options .--bare. and .--origin foo. cannot be used together" err
 
 '
 
@@ -54,7 +54,7 @@
 
 	test_must_fail git clone --bare --separate-git-dir dot-git-destiation parent clone-bare-sgd 2>err &&
 	test_debug "cat err" &&
-	test_i18ngrep -e "--bare and --separate-git-dir are incompatible" err
+	test_i18ngrep -e "options .--bare. and .--separate-git-dir. cannot be used together" err
 
 '
 
diff --git a/t/t5609-clone-branch.sh b/t/t5609-clone-branch.sh
index f86a674..252e1f7 100755
--- a/t/t5609-clone-branch.sh
+++ b/t/t5609-clone-branch.sh
@@ -4,6 +4,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 check_HEAD() {
diff --git a/t/t5611-clone-config.sh b/t/t5611-clone-config.sh
index f8625f9..4b38772 100755
--- a/t/t5611-clone-config.sh
+++ b/t/t5611-clone-config.sh
@@ -17,7 +17,7 @@
 test_expect_success 'clone -c can set multi-keys' '
 	rm -rf child &&
 	git clone -c core.foo=bar -c core.foo=baz . child &&
-	{ echo bar; echo baz; } >expect &&
+	test_write_lines bar baz >expect &&
 	git --git-dir=child/.git config --get-all core.foo >actual &&
 	test_cmp expect actual
 '
diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
index cf3e82b..34469b6 100755
--- a/t/t5616-partial-clone.sh
+++ b/t/t5616-partial-clone.sh
@@ -16,10 +16,10 @@
 	git init src &&
 	for n in 1 2 3 4
 	do
-		echo "This is file: $n" > src/file.$n.txt
-		git -C src add file.$n.txt
-		git -C src commit -m "file $n"
-		git -C src ls-files -s file.$n.txt >>temp
+		echo "This is file: $n" > src/file.$n.txt &&
+		git -C src add file.$n.txt &&
+		git -C src commit -m "file $n" &&
+		git -C src ls-files -s file.$n.txt >>temp || return 1
 	done &&
 	awk -f print_2.awk <temp | sort >expect_1.oids &&
 	test_line_count = 4 expect_1.oids
@@ -72,9 +72,9 @@
 	git -C src remote add srv "file://$(pwd)/srv.bare" &&
 	for x in a b c d e
 	do
-		echo "Mod file.1.txt $x" >>src/file.1.txt
-		git -C src add file.1.txt
-		git -C src commit -m "mod $x"
+		echo "Mod file.1.txt $x" >>src/file.1.txt &&
+		git -C src add file.1.txt &&
+		git -C src commit -m "mod $x" || return 1
 	done &&
 	git -C src blame main -- file.1.txt >expect.blame &&
 	git -C src push -u srv main
@@ -114,9 +114,9 @@
 test_expect_success 'push new commits to server for file.2.txt' '
 	for x in a b c d e f
 	do
-		echo "Mod file.2.txt $x" >>src/file.2.txt
-		git -C src add file.2.txt
-		git -C src commit -m "mod $x"
+		echo "Mod file.2.txt $x" >>src/file.2.txt &&
+		git -C src add file.2.txt &&
+		git -C src commit -m "mod $x" || return 1
 	done &&
 	git -C src push -u srv main
 '
@@ -135,9 +135,9 @@
 test_expect_success 'push new commits to server for file.3.txt' '
 	for x in a b c d e f
 	do
-		echo "Mod file.3.txt $x" >>src/file.3.txt
-		git -C src add file.3.txt
-		git -C src commit -m "mod $x"
+		echo "Mod file.3.txt $x" >>src/file.3.txt &&
+		git -C src add file.3.txt &&
+		git -C src commit -m "mod $x" || return 1
 	done &&
 	git -C src push -u srv main
 '
@@ -385,7 +385,7 @@
 	for i in $(test_seq 1 100)
 	do
 		echo "make the tree big" >server/file$i &&
-		git -C server add file$i
+		git -C server add file$i || return 1
 	done &&
 	git -C server commit -m "initial" &&
 	git clone --bare --filter=tree:0 "file://$(pwd)/server" client &&
@@ -669,7 +669,7 @@
 	for i in $(test_seq 10)
 	do
 		echo "this is a line" >>"$SERVER/foo.txt" &&
-		echo "this is another line" >>"$SERVER/have.txt"
+		echo "this is another line" >>"$SERVER/have.txt" || return 1
 	done &&
 	git -C "$SERVER" add foo.txt have.txt &&
 	git -C "$SERVER" commit -m bar &&
diff --git a/t/t5701-git-serve.sh b/t/t5701-git-serve.sh
index aa1827d..1896f67 100755
--- a/t/t5701-git-serve.sh
+++ b/t/t5701-git-serve.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'test capability advertisement' '
diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index d527cf6..710f33e 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -747,7 +747,7 @@
 		echo "data 0" &&
 		echo "M 644 inline bla.txt" &&
 		echo "data 4" &&
-		echo "bla"
+		echo "bla" || return 1
 	done | git -C "$HTTPD_DOCUMENT_ROOT_PATH/big" fast-import &&
 
 	GIT_TRACE_PACKET="$(pwd)/log" GIT_TRACE_CURL="$(pwd)/log" git \
@@ -942,7 +942,7 @@
 			then
 				>h2found
 			fi
-		fi
+		fi || return 1
 	done &&
 	test -f hfound &&
 	test -f h2found &&
@@ -1107,6 +1107,57 @@
 	test_i18ngrep "disallowed submodule name" err
 '
 
+test_expect_success 'packfile-uri path redacted in trace' '
+	P="$HTTPD_DOCUMENT_ROOT_PATH/http_parent" &&
+	rm -rf "$P" http_child log &&
+
+	git init "$P" &&
+	git -C "$P" config "uploadpack.allowsidebandall" "true" &&
+
+	echo my-blob >"$P/my-blob" &&
+	git -C "$P" add my-blob &&
+	git -C "$P" commit -m x &&
+
+	git -C "$P" hash-object my-blob >objh &&
+	git -C "$P" pack-objects "$HTTPD_DOCUMENT_ROOT_PATH/mypack" <objh >packh &&
+	git -C "$P" config --add \
+		"uploadpack.blobpackfileuri" \
+		"$(cat objh) $(cat packh) $HTTPD_URL/dumb/mypack-$(cat packh).pack" &&
+
+	GIT_TRACE_PACKET="$(pwd)/log" \
+	git -c protocol.version=2 \
+		-c fetch.uriprotocols=http,https \
+		clone "$HTTPD_URL/smart/http_parent" http_child &&
+
+	grep -F "clone< \\1$(cat packh) $HTTPD_URL/<redacted>" log
+'
+
+test_expect_success 'packfile-uri path not redacted in trace when GIT_TRACE_REDACT=0' '
+	P="$HTTPD_DOCUMENT_ROOT_PATH/http_parent" &&
+	rm -rf "$P" http_child log &&
+
+	git init "$P" &&
+	git -C "$P" config "uploadpack.allowsidebandall" "true" &&
+
+	echo my-blob >"$P/my-blob" &&
+	git -C "$P" add my-blob &&
+	git -C "$P" commit -m x &&
+
+	git -C "$P" hash-object my-blob >objh &&
+	git -C "$P" pack-objects "$HTTPD_DOCUMENT_ROOT_PATH/mypack" <objh >packh &&
+	git -C "$P" config --add \
+		"uploadpack.blobpackfileuri" \
+		"$(cat objh) $(cat packh) $HTTPD_URL/dumb/mypack-$(cat packh).pack" &&
+
+	GIT_TRACE_PACKET="$(pwd)/log" \
+	GIT_TRACE_REDACT=0 \
+	git -c protocol.version=2 \
+		-c fetch.uriprotocols=http,https \
+		clone "$HTTPD_URL/smart/http_parent" http_child &&
+
+	grep -F "clone< \\1$(cat packh) $HTTPD_URL/dumb/mypack-$(cat packh).pack" log
+'
+
 test_expect_success 'http:// --negotiate-only' '
 	SERVER="$HTTPD_DOCUMENT_ROOT_PATH/server" &&
 	URI="$HTTPD_URL/smart/server" &&
diff --git a/t/t5703-upload-pack-ref-in-want.sh b/t/t5703-upload-pack-ref-in-want.sh
index 2200985..9d6cd7d 100755
--- a/t/t5703-upload-pack-ref-in-want.sh
+++ b/t/t5703-upload-pack-ref-in-want.sh
@@ -2,9 +2,6 @@
 
 test_description='upload-pack ref-in-want'
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 
 get_actual_refs () {
diff --git a/t/t5704-protocol-violations.sh b/t/t5704-protocol-violations.sh
index bc393d7..ae1a00a 100755
--- a/t/t5704-protocol-violations.sh
+++ b/t/t5704-protocol-violations.sh
@@ -4,6 +4,8 @@
 of these cases it will generally be acceptable for one side to break off
 communications if the other side says something unexpected. We are mostly
 making sure that we do not segfault or otherwise behave badly.'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'extra delim packet in v2 ls-refs args' '
diff --git a/t/t5705-session-id-in-capabilities.sh b/t/t5705-session-id-in-capabilities.sh
index eb8c79a..ed38c76 100755
--- a/t/t5705-session-id-in-capabilities.sh
+++ b/t/t5705-session-id-in-capabilities.sh
@@ -32,7 +32,6 @@
 		test_when_finished "git -C local push --delete origin new-branch" &&
 		cp -r "$LOCAL_PRISTINE" local &&
 		git -C local pull --no-rebase origin &&
-		GIT_TRACE2_EVENT_NESTING=5 \
 		GIT_TRACE2_EVENT="$(pwd)/tr2-client-events" \
 		git -c protocol.version=$PROTO -C local push \
 			--receive-pack "GIT_TRACE2_EVENT=\"$(pwd)/tr2-server-events\" git-receive-pack" \
@@ -65,7 +64,6 @@
 		test_when_finished "git -C local push --delete origin new-branch" &&
 		cp -r "$LOCAL_PRISTINE" local &&
 		git -C local pull --no-rebase origin &&
-		GIT_TRACE2_EVENT_NESTING=5 \
 		GIT_TRACE2_EVENT="$(pwd)/tr2-client-events" \
 		git -c protocol.version=$PROTO -C local push \
 			--receive-pack "GIT_TRACE2_EVENT=\"$(pwd)/tr2-server-events\" git-receive-pack" \
diff --git a/t/t6005-rev-list-count.sh b/t/t6005-rev-list-count.sh
index 0b64822..86542c6 100755
--- a/t/t6005-rev-list-count.sh
+++ b/t/t6005-rev-list-count.sh
@@ -2,13 +2,14 @@
 
 test_description='git rev-list --max-count and --skip test'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
-    for n in 1 2 3 4 5 ; do \
-        echo $n > a ; \
-        git add a ; \
-        git commit -m "$n" ; \
+    for n in 1 2 3 4 5 ; do
+	echo $n > a &&
+	git add a &&
+	git commit -m "$n" || return 1
     done
 '
 
diff --git a/t/t6009-rev-list-parent.sh b/t/t6009-rev-list-parent.sh
index 63fa7c8..5a67bbc 100755
--- a/t/t6009-rev-list-parent.sh
+++ b/t/t6009-rev-list-parent.sh
@@ -124,7 +124,7 @@
 		git checkout -b root$i five &&
 		test_commit $i &&
 		roots="$roots root$i" ||
-		return
+		return 1
 	done &&
 	git checkout main &&
 	test_tick &&
@@ -142,8 +142,8 @@
 
 	test_tick_keep=$test_tick &&
 	for i in 1 2 3 4 5 6 7 8; do
-		test_tick=$test_tick_keep
-		test_commit t$i
+		test_tick=$test_tick_keep &&
+		test_commit t$i || return 1
 	done &&
 	git rev-list t1^! --not t$i >result &&
 	test_must_be_empty result
diff --git a/t/t6019-rev-list-ancestry-path.sh b/t/t6019-rev-list-ancestry-path.sh
index 20adbec..af57a04 100755
--- a/t/t6019-rev-list-ancestry-path.sh
+++ b/t/t6019-rev-list-ancestry-path.sh
@@ -51,7 +51,7 @@
 '
 
 test_expect_success 'rev-list D..M' '
-	for c in E F G H I J K L M; do echo $c; done >expect &&
+	test_write_lines E F G H I J K L M >expect &&
 	git rev-list --format=%s D..M |
 	sed -e "/^commit /d" |
 	sort >actual &&
@@ -59,7 +59,7 @@
 '
 
 test_expect_success 'rev-list --ancestry-path D..M' '
-	for c in E F H I J L M; do echo $c; done >expect &&
+	test_write_lines E F H I J L M >expect &&
 	git rev-list --ancestry-path --format=%s D..M |
 	sed -e "/^commit /d" |
 	sort >actual &&
@@ -81,7 +81,7 @@
 '
 
 test_expect_success 'rev-list F...I' '
-	for c in F G H I; do echo $c; done >expect &&
+	test_write_lines F G H I >expect &&
 	git rev-list --format=%s F...I |
 	sed -e "/^commit /d" |
 	sort >actual &&
@@ -89,7 +89,7 @@
 '
 
 test_expect_success 'rev-list --ancestry-path F...I' '
-	for c in F H I; do echo $c; done >expect &&
+	test_write_lines F H I >expect &&
 	git rev-list --ancestry-path --format=%s F...I |
 	sed -e "/^commit /d" |
 	sort >actual &&
@@ -111,7 +111,7 @@
 '
 
 test_expect_success 'rev-list --ancestry-path --simplify-merges G^..M -- G.t' '
-	for c in G L; do echo $c; done >expect &&
+	test_write_lines G L >expect &&
 	git rev-list --ancestry-path --simplify-merges --format=%s G^..M -- G.t |
 	sed -e "/^commit /d" |
 	sort >actual &&
diff --git a/t/t6060-merge-index.sh b/t/t6060-merge-index.sh
index ddf34f0..ed449ab 100755
--- a/t/t6060-merge-index.sh
+++ b/t/t6060-merge-index.sh
@@ -4,9 +4,7 @@
 . ./test-lib.sh
 
 test_expect_success 'setup diverging branches' '
-	for i in 1 2 3 4 5 6 7 8 9 10; do
-		echo $i
-	done >file &&
+	test_write_lines 1 2 3 4 5 6 7 8 9 10 >file &&
 	git add file &&
 	git commit -m base &&
 	git tag base &&
diff --git a/t/t6101-rev-parse-parents.sh b/t/t6101-rev-parse-parents.sh
index 78b5851..c571fa5 100755
--- a/t/t6101-rev-parse-parents.sh
+++ b/t/t6101-rev-parse-parents.sh
@@ -32,7 +32,7 @@
 		test_tick &&
 		git commit --allow-empty -m "$i" &&
 		commit=$(git rev-parse --verify HEAD) &&
-		printf "$commit " >>.git/info/grafts
+		printf "$commit " >>.git/info/grafts || return 1
 	done
 '
 
diff --git a/t/t6102-rev-list-unexpected-objects.sh b/t/t6102-rev-list-unexpected-objects.sh
index 52cde09..6f0902b 100755
--- a/t/t6102-rev-list-unexpected-objects.sh
+++ b/t/t6102-rev-list-unexpected-objects.sh
@@ -2,6 +2,7 @@
 
 test_description='git rev-list should handle unexpected object types'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup well-formed objects' '
diff --git a/t/t6112-rev-list-filters-objects.sh b/t/t6112-rev-list-filters-objects.sh
index 4ade105..8d9d660 100755
--- a/t/t6112-rev-list-filters-objects.sh
+++ b/t/t6112-rev-list-filters-objects.sh
@@ -16,9 +16,9 @@
 	git init r1 &&
 	for n in 1 2 3 4 5
 	do
-		echo "This is file: $n" > r1/file.$n
-		git -C r1 add file.$n
-		git -C r1 commit -m "$n"
+		echo "This is file: $n" > r1/file.$n &&
+		git -C r1 add file.$n &&
+		git -C r1 commit -m "$n" || return 1
 	done
 '
 
@@ -73,9 +73,9 @@
 	git init r2 &&
 	for n in 1000 10000
 	do
-		printf "%"$n"s" X > r2/large.$n
-		git -C r2 add large.$n
-		git -C r2 commit -m "$n"
+		printf "%"$n"s" X > r2/large.$n &&
+		git -C r2 add large.$n &&
+		git -C r2 commit -m "$n" || return 1
 	done
 '
 
@@ -245,10 +245,10 @@
 	mkdir r3/dir1 &&
 	for n in sparse1 sparse2
 	do
-		echo "This is file: $n" > r3/$n
-		git -C r3 add $n
-		echo "This is file: dir1/$n" > r3/dir1/$n
-		git -C r3 add dir1/$n
+		echo "This is file: $n" > r3/$n &&
+		git -C r3 add $n &&
+		echo "This is file: dir1/$n" > r3/dir1/$n &&
+		git -C r3 add dir1/$n || return 1
 	done &&
 	git -C r3 commit -m "sparse" &&
 	echo dir1/ >pattern1 &&
@@ -672,7 +672,7 @@
 
 	for id in `cat expected | sed "s|..|&/|"`
 	do
-		rm r1/.git/objects/$id
+		rm r1/.git/objects/$id || return 1
 	done &&
 
 	git -C r1 rev-list --quiet --missing=print --objects HEAD >revs &&
diff --git a/t/t6120-describe.sh b/t/t6120-describe.sh
index bae2419..d8af2bb 100755
--- a/t/t6120-describe.sh
+++ b/t/t6120-describe.sh
@@ -262,7 +262,7 @@
 	>expect.unsorted &&
 	for rev in $(git rev-list --all)
 	do
-		git name-rev $rev >>expect.unsorted
+		git name-rev $rev >>expect.unsorted || return 1
 	done &&
 	sort <expect.unsorted >expect &&
 	git name-rev --all >actual.unsorted &&
@@ -275,7 +275,7 @@
 	for rev in $(git rev-list --all)
 	do
 		name=$(git name-rev --name-only $rev) &&
-		echo "$rev ($name)" >>expect.unsorted
+		echo "$rev ($name)" >>expect.unsorted || return 1
 	done &&
 	sort <expect.unsorted >expect &&
 	git rev-list --all | git name-rev --stdin >actual.unsorted &&
@@ -390,9 +390,12 @@
 committer A U Thor <author@example.com> $((1000000000 + $i * 100)) +0200
 data <<EOF
 commit #$i
-EOF"
-		test $i = 1 && echo "from refs/heads/main^0"
-		i=$(($i + 1))
+EOF" &&
+		if test $i = 1
+		then
+			echo "from refs/heads/main^0"
+		fi &&
+		i=$(($i + 1)) || return 1
 	done | git fast-import &&
 	git checkout main &&
 	git tag far-far-away HEAD^ &&
diff --git a/t/t6132-pathspec-exclude.sh b/t/t6132-pathspec-exclude.sh
index 30328b8..8ff1d76 100755
--- a/t/t6132-pathspec-exclude.sh
+++ b/t/t6132-pathspec-exclude.sh
@@ -11,7 +11,7 @@
 		fi &&
 		: >$p &&
 		git add $p &&
-		git commit -m $p
+		git commit -m $p || return 1
 	done &&
 	git log --oneline --format=%s >actual &&
 	cat <<EOF >expect &&
diff --git a/t/t6136-pathspec-in-bare.sh b/t/t6136-pathspec-in-bare.sh
index b117251..ae8b537 100755
--- a/t/t6136-pathspec-in-bare.sh
+++ b/t/t6136-pathspec-in-bare.sh
@@ -2,6 +2,7 @@
 
 test_description='diagnosing out-of-scope pathspec'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup a bare and non-bare repository' '
diff --git a/t/t6200-fmt-merge-msg.sh b/t/t6200-fmt-merge-msg.sh
index 06c5fb5..5a221f8 100755
--- a/t/t6200-fmt-merge-msg.sh
+++ b/t/t6200-fmt-merge-msg.sh
@@ -91,6 +91,26 @@
 	git tag -s -u"${GPGSSH_KEY_UNTRUSTED}" -m signed-ssh-tag-msg-untrusted signed-untrusted-ssh-tag left
 '
 
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'create signed tags with keys having defined lifetimes' '
+	test_when_finished "test_unconfig commit.gpgsign" &&
+	test_config gpg.format ssh &&
+	git checkout -b signed-expiry-ssh &&
+	touch file &&
+	git add file &&
+
+	echo expired >file && test_tick && git commit -a -m expired -S"${GPGSSH_KEY_EXPIRED}" &&
+	git tag -s -u "${GPGSSH_KEY_EXPIRED}" -m expired-signed expired-signed &&
+
+	echo notyetvalid >file && test_tick && git commit -a -m notyetvalid -S"${GPGSSH_KEY_NOTYETVALID}" &&
+	git tag -s -u "${GPGSSH_KEY_NOTYETVALID}" -m notyetvalid-signed notyetvalid-signed &&
+
+	echo timeboxedvalid >file && test_tick && git commit -a -m timeboxedvalid -S"${GPGSSH_KEY_TIMEBOXEDVALID}" &&
+	git tag -s -u "${GPGSSH_KEY_TIMEBOXEDVALID}" -m timeboxedvalid-signed timeboxedvalid-signed &&
+
+	echo timeboxedinvalid >file && test_tick && git commit -a -m timeboxedinvalid -S"${GPGSSH_KEY_TIMEBOXEDINVALID}" &&
+	git tag -s -u "${GPGSSH_KEY_TIMEBOXEDINVALID}" -m timeboxedinvalid-signed timeboxedinvalid-signed
+'
+
 test_expect_success 'message for merging local branch' '
 	echo "Merge branch ${apos}left${apos}" >expected &&
 
@@ -104,8 +124,9 @@
 test_expect_success GPG 'message for merging local tag signed by good key' '
 	git checkout main &&
 	git fetch . signed-good-tag &&
-	git fmt-merge-msg <.git/FETCH_HEAD >actual 2>&1 &&
+	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
 	grep "^Merge tag ${apos}signed-good-tag${apos}" actual &&
+	grep "^signed-tag-msg" actual &&
 	grep "^# gpg: Signature made" actual &&
 	grep "^# gpg: Good signature from" actual
 '
@@ -113,8 +134,9 @@
 test_expect_success GPG 'message for merging local tag signed by unknown key' '
 	git checkout main &&
 	git fetch . signed-good-tag &&
-	GNUPGHOME=. git fmt-merge-msg <.git/FETCH_HEAD >actual 2>&1 &&
+	GNUPGHOME=. git fmt-merge-msg <.git/FETCH_HEAD >actual &&
 	grep "^Merge tag ${apos}signed-good-tag${apos}" actual &&
+	grep "^signed-tag-msg" actual &&
 	grep "^# gpg: Signature made" actual &&
 	grep -E "^# gpg: Can${apos}t check signature: (public key not found|No public key)" actual
 '
@@ -123,7 +145,9 @@
 	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
 	git checkout main &&
 	git fetch . signed-good-ssh-tag &&
-	git fmt-merge-msg <.git/FETCH_HEAD >actual 2>&1 &&
+	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
+	grep "^Merge tag ${apos}signed-good-ssh-tag${apos}" actual &&
+	grep "^signed-ssh-tag-msg" actual &&
 	grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual &&
 	! grep "${GPGSSH_BAD_SIGNATURE}" actual
 '
@@ -132,11 +156,55 @@
 	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
 	git checkout main &&
 	git fetch . signed-untrusted-ssh-tag &&
-	git fmt-merge-msg <.git/FETCH_HEAD >actual 2>&1 &&
+	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
+	grep "^Merge tag ${apos}signed-untrusted-ssh-tag${apos}" actual &&
+	grep "^signed-ssh-tag-msg-untrusted" actual &&
 	grep "${GPGSSH_GOOD_SIGNATURE_UNTRUSTED}" actual &&
 	! grep "${GPGSSH_BAD_SIGNATURE}" actual &&
 	grep "${GPGSSH_KEY_NOT_TRUSTED}" actual
 '
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'message for merging local tag signed by expired ssh key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git checkout main &&
+	git fetch . expired-signed &&
+	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
+	grep "^Merge tag ${apos}expired-signed${apos}" actual &&
+	grep "^expired-signed" actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'message for merging local tag signed by not yet valid ssh key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git checkout main &&
+	git fetch . notyetvalid-signed &&
+	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
+	grep "^Merge tag ${apos}notyetvalid-signed${apos}" actual &&
+	grep "^notyetvalid-signed" actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'message for merging local tag signed by valid timeboxed ssh key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git checkout main &&
+	git fetch . timeboxedvalid-signed &&
+	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
+	grep "^Merge tag ${apos}timeboxedvalid-signed${apos}" actual &&
+	grep "^timeboxedvalid-signed" actual &&
+	grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual &&
+	! grep "${GPGSSH_BAD_SIGNATURE}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'message for merging local tag signed by invalid timeboxed ssh key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git checkout main &&
+	git fetch . timeboxedinvalid-signed &&
+	git fmt-merge-msg <.git/FETCH_HEAD >actual &&
+	grep "^Merge tag ${apos}timeboxedinvalid-signed${apos}" actual &&
+	grep "^timeboxedinvalid-signed" actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
 test_expect_success 'message for merging external branch' '
 	echo "Merge branch ${apos}left${apos} of $(pwd)" >expected &&
 
@@ -519,7 +587,7 @@
 		while test $i -gt 9
 		do
 			echo "  $i" &&
-			i=$(($i-1))
+			i=$(($i-1)) || return 1
 		done &&
 		echo "  ..."
 	} >expected &&
@@ -573,7 +641,35 @@
 	test_cmp expected .git/MERGE_MSG
 '
 
+test_expect_success 'merge --into-name=<name>' '
+	test_when_finished "git checkout main" &&
+	git checkout -B side main &&
+	git commit --allow-empty -m "One step ahead" &&
+
+	git checkout --detach main &&
+	git merge --no-ff side &&
+	git show -s --format="%s" >full.0 &&
+	head -n1 full.0 >actual &&
+	# expect that HEAD is shown as-is
+	grep -e "Merge branch .side. into HEAD$" actual &&
+
+	git reset --hard main &&
+	git merge --no-ff --into-name=main side &&
+	git show -s --format="%s" >full.1 &&
+	head -n1 full.1 >actual &&
+	# expect that we pretend to be merging to main, that is suppressed
+	grep -e "Merge branch .side.$" actual &&
+
+	git checkout -b throwaway main &&
+	git merge --no-ff --into-name=main side &&
+	git show -s --format="%s" >full.2 &&
+	head -n1 full.2 >actual &&
+	# expect that we pretend to be merging to main, that is suppressed
+	grep -e "Merge branch .side.$" actual
+'
+
 test_expect_success 'merge.suppressDest configuration' '
+	test_when_finished "git checkout main" &&
 	git checkout -B side main &&
 	git commit --allow-empty -m "One step ahead" &&
 	git checkout main &&
@@ -590,7 +686,19 @@
 	git -c merge.suppressDest="ma?*[rn]" fmt-merge-msg <.git/FETCH_HEAD >full.3 &&
 	head -n1 full.3 >actual &&
 	grep -e "Merge branch .side." actual &&
-	! grep -e " into main$" actual
+	! grep -e " into main$" actual &&
+
+	git checkout --detach HEAD &&
+	git -c merge.suppressDest="main" fmt-merge-msg <.git/FETCH_HEAD >full.4 &&
+	head -n1 full.4 >actual &&
+	grep -e "Merge branch .side. into HEAD$" actual &&
+
+	git -c merge.suppressDest="main" fmt-merge-msg \
+		--into-name=main <.git/FETCH_HEAD >full.5 &&
+	head -n1 full.5 >actual &&
+	grep -e "Merge branch .side." actual &&
+	! grep -e " into main$" actual &&
+	! grep -e " into HEAD$" actual
 '
 
 test_done
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index 80679d5..dcaab72 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -5,9 +5,6 @@
 
 test_description='for-each-ref test'
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-gpg.sh
 . "$TEST_DIRECTORY"/lib-terminal.sh
@@ -419,6 +416,11 @@
 	test_cmp expected actual
 '
 
+test_expect_success 'Give help even with invalid sort atoms' '
+	test_expect_code 129 git for-each-ref --sort=bogus -h >actual 2>&1 &&
+	grep "^usage: git for-each-ref" actual
+'
+
 cat >expected <<\EOF
 refs/tags/testtag
 refs/tags/testtag-2
@@ -950,10 +952,7 @@
 '
 
 test_expect_success '%(raw:size) with --shell' '
-	git for-each-ref --format="%(raw:size)" | while read line
-	do
-		echo "'\''$line'\''" >>expect
-	done &&
+	git for-each-ref --format="%(raw:size)" | sed "s/^/$SQ/;s/$/$SQ/" >expect &&
 	git for-each-ref --format="%(raw:size)" --shell >actual &&
 	test_cmp expect actual
 '
@@ -1019,6 +1018,27 @@
 	test_cmp expected actual
 '
 
+test_expect_success '--no-sort cancels the previous sort keys' '
+	cat >expected <<-\EOF &&
+	100000 <user1@example.com> refs/tags/multi-ref1-100000-user1
+	100000 <user2@example.com> refs/tags/multi-ref1-100000-user2
+	100000 <user1@example.com> refs/tags/multi-ref2-100000-user1
+	100000 <user2@example.com> refs/tags/multi-ref2-100000-user2
+	200000 <user1@example.com> refs/tags/multi-ref1-200000-user1
+	200000 <user2@example.com> refs/tags/multi-ref1-200000-user2
+	200000 <user1@example.com> refs/tags/multi-ref2-200000-user1
+	200000 <user2@example.com> refs/tags/multi-ref2-200000-user2
+	EOF
+	git for-each-ref \
+		--format="%(taggerdate:unix) %(taggeremail) %(refname)" \
+		--sort=-refname \
+		--sort=taggeremail \
+		--no-sort \
+		--sort=taggerdate \
+		"refs/tags/multi-*" >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'do not dereference NULL upon %(HEAD) on unborn branch' '
 	test_when_finished "git checkout main" &&
 	git for-each-ref --format="%(HEAD) %(refname:short)" refs/heads/ >actual &&
@@ -1315,7 +1335,7 @@
 			echo "${pair#*=}" >expect &&
 			git for-each-ref --format="${pair%=*}" \
 				refs/heads/main >actual &&
-			test_cmp expect actual
+			test_cmp expect actual || exit 1
 		done &&
 		git branch push-simple &&
 		git config branch.push-simple.pushRemote from &&
diff --git a/t/t6302-for-each-ref-filter.sh b/t/t6302-for-each-ref-filter.sh
index 1537aa2..1ce5f49 100755
--- a/t/t6302-for-each-ref-filter.sh
+++ b/t/t6302-for-each-ref-filter.sh
@@ -2,9 +2,6 @@
 
 test_description='test for-each-refs usage of ref-filter APIs'
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-gpg.sh
 
diff --git a/t/t6406-merge-attr.sh b/t/t6406-merge-attr.sh
index 8494645..57e6af5 100755
--- a/t/t6406-merge-attr.sh
+++ b/t/t6406-merge-attr.sh
@@ -62,10 +62,10 @@
 
 test_expect_success merge '
 
-	{
-		echo "binary -merge"
-		echo "union merge=union"
-	} >.gitattributes &&
+	cat >.gitattributes <<-\EOF &&
+	binary -merge
+	union merge=union
+	EOF
 
 	if git merge main
 	then
diff --git a/t/t6407-merge-binary.sh b/t/t6407-merge-binary.sh
index d4273f2..8e6241f 100755
--- a/t/t6407-merge-binary.sh
+++ b/t/t6407-merge-binary.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '
@@ -47,7 +48,7 @@
 		echo Oops, should not have succeeded
 		false
 	else
-		git ls-files -s >current
+		git ls-files -s >current &&
 		test_cmp expect current
 	fi
 '
@@ -62,7 +63,7 @@
 		echo Oops, should not have succeeded
 		false
 	else
-		git ls-files -s >current
+		git ls-files -s >current &&
 		test_cmp expect current
 	fi
 '
diff --git a/t/t6409-merge-subtree.sh b/t/t6409-merge-subtree.sh
index ba7890e..e9ba6f1 100755
--- a/t/t6409-merge-subtree.sh
+++ b/t/t6409-merge-subtree.sh
@@ -10,7 +10,7 @@
 test_expect_success setup '
 
 	s="1 2 3 4 5 6 7 8" &&
-	for i in $s; do echo $i; done >hello &&
+	test_write_lines $s >hello &&
 	git add hello &&
 	git commit -m initial &&
 	git checkout -b side &&
@@ -18,7 +18,7 @@
 	git add hello &&
 	git commit -m second &&
 	git checkout main &&
-	for i in mundo $s; do echo $i; done >hello &&
+	test_write_lines mundo $s >hello &&
 	git add hello &&
 	git commit -m main
 
@@ -27,7 +27,7 @@
 test_expect_success 'subtree available and works like recursive' '
 
 	git merge -s subtree side &&
-	for i in mundo $s world; do echo $i; done >expect &&
+	test_write_lines mundo $s world >expect &&
 	test_cmp expect hello
 
 '
diff --git a/t/t6411-merge-filemode.sh b/t/t6411-merge-filemode.sh
index f54c915..6ae2489 100755
--- a/t/t6411-merge-filemode.sh
+++ b/t/t6411-merge-filemode.sh
@@ -51,10 +51,10 @@
 	: >file2 &&
 	git add file2 &&
 	git commit -m b2 &&
-	{
-		echo "100755 $H 2	file2"
-		echo "100644 $H 3	file2"
-	} >expect
+	cat >expect <<-EOF
+	100755 $H 2	file2
+	100644 $H 3	file2
+	EOF
 '
 
 do_both_modes () {
diff --git a/t/t6412-merge-large-rename.sh b/t/t6412-merge-large-rename.sh
index c50d315..ca018d1 100755
--- a/t/t6412-merge-large-rename.sh
+++ b/t/t6412-merge-large-rename.sh
@@ -37,18 +37,18 @@
 	test_might_fail git branch -D test$n &&
 	git reset --hard initial &&
 	for i in $(count $n); do
-		make_text $i initial initial >$i
+		make_text $i initial initial >$i || return 1
 	done &&
 	git add . &&
 	git commit -m add=$n &&
 	for i in $(count $n); do
-		make_text $i changed initial >$i
+		make_text $i changed initial >$i || return 1
 	done &&
 	git commit -a -m change=$n &&
 	git checkout -b test$n HEAD^ &&
 	for i in $(count $n); do
-		git rm $i
-		make_text $i initial changed >$i.moved
+		git rm $i &&
+		make_text $i initial changed >$i.moved || return 1
 	done &&
 	git add . &&
 	git commit -m change+rename=$n &&
@@ -79,7 +79,7 @@
 
 	git reset --hard initial &&
 	for i in $(count 200); do
-		make_text foo bar baz >$i
+		make_text foo bar baz >$i || return 1
 	done &&
 	git add . &&
 	git commit -m create-files &&
diff --git a/t/t6414-merge-rename-nocruft.sh b/t/t6414-merge-rename-nocruft.sh
index d7e3c1f..69fc1c9 100755
--- a/t/t6414-merge-rename-nocruft.sh
+++ b/t/t6414-merge-rename-nocruft.sh
@@ -4,6 +4,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t6416-recursive-corner-cases.sh b/t/t6416-recursive-corner-cases.sh
index 84f5082..690c848 100755
--- a/t/t6416-recursive-corner-cases.sh
+++ b/t/t6416-recursive-corner-cases.sh
@@ -24,14 +24,8 @@
 		cd basic-rename &&
 
 		ten="0 1 2 3 4 5 6 7 8 9" &&
-		for i in $ten
-		do
-			echo line $i in a sample file
-		done >one &&
-		for i in $ten
-		do
-			echo line $i in another sample file
-		done >two &&
+		printf "line %d in a sample file\n" $ten >one &&
+		printf "line %d in another sample file\n" $ten >two &&
 		git add one two &&
 		test_tick && git commit -m initial &&
 
@@ -96,14 +90,8 @@
 		cd rename-modify &&
 
 		ten="0 1 2 3 4 5 6 7 8 9" &&
-		for i in $ten
-		do
-			echo line $i in a sample file
-		done >one &&
-		for i in $ten
-		do
-			echo line $i in another sample file
-		done >two &&
+		printf "line %d in a sample file\n" $ten >one &&
+		printf "line %d in another sample file\n" $ten >two &&
 		git add one two &&
 		test_tick && git commit -m initial &&
 
@@ -1588,10 +1576,7 @@
 		cd nested_conflicts &&
 
 		# Create some related files now
-		for i in $(test_seq 1 10)
-		do
-			echo Random base content line $i
-		done >initial &&
+		printf "Random base content line %d\n" $(test_seq 1 10) >initial &&
 
 		cp initial b_L1 &&
 		cp initial b_R1 &&
@@ -1777,10 +1762,7 @@
 		cd virtual_merge_base_has_nested_conflicts &&
 
 		# Create some related files now
-		for i in $(test_seq 1 10)
-		do
-			echo Random base content line $i
-		done >content &&
+		printf "Random base content line %d\n" $(test_seq 1 10) >content &&
 
 		# Setup original commit
 		git add content &&
diff --git a/t/t6417-merge-ours-theirs.sh b/t/t6417-merge-ours-theirs.sh
index ec065d6..62d1406 100755
--- a/t/t6417-merge-ours-theirs.sh
+++ b/t/t6417-merge-ours-theirs.sh
@@ -7,10 +7,7 @@
 . ./test-lib.sh
 
 test_expect_success setup '
-	for i in 1 2 3 4 5 6 7 8 9
-	do
-		echo "$i"
-	done >file &&
+	test_write_lines 1 2 3 4 5 6 7 8 9 >file &&
 	git add file &&
 	cp file elif &&
 	git commit -m initial &&
diff --git a/t/t6418-merge-text-auto.sh b/t/t6418-merge-text-auto.sh
index 1e0296d..41288a6 100755
--- a/t/t6418-merge-text-auto.sh
+++ b/t/t6418-merge-text-auto.sh
@@ -204,4 +204,30 @@
 	test_path_is_missing file
 '
 
+test_expect_success 'rename/delete vs. renormalization' '
+	git init subrepo &&
+	(
+		cd subrepo &&
+		echo foo >oldfile &&
+		git add oldfile &&
+		git commit -m original &&
+
+		git branch rename &&
+		git branch nuke &&
+
+		git checkout rename &&
+		git mv oldfile newfile &&
+		git commit -m renamed &&
+
+		git checkout nuke &&
+		git rm oldfile &&
+		git commit -m deleted &&
+
+		git checkout rename^0 &&
+		test_must_fail git -c merge.renormalize=true merge nuke >out &&
+
+		grep "rename/delete" out
+	)
+'
+
 test_done
diff --git a/t/t6427-diff3-conflict-markers.sh b/t/t6427-diff3-conflict-markers.sh
index 25c4b72..a9ee4cb 100755
--- a/t/t6427-diff3-conflict-markers.sh
+++ b/t/t6427-diff3-conflict-markers.sh
@@ -211,4 +211,94 @@
 	)
 '
 
+test_setup_zdiff3 () {
+	test_create_repo zdiff3 &&
+	(
+		cd zdiff3 &&
+
+		test_write_lines 1 2 3 4 5 6 7 8 9 >basic &&
+		test_write_lines 1 2 3 AA 4 5 BB 6 7 8 >middle-common &&
+		test_write_lines 1 2 3 4 5 6 7 8 9 >interesting &&
+		test_write_lines 1 2 3 4 5 6 7 8 9 >evil &&
+
+		git add basic middle-common interesting evil &&
+		git commit -m base &&
+
+		git branch left &&
+		git branch right &&
+
+		git checkout left &&
+		test_write_lines 1 2 3 4 A B C D E 7 8 9 >basic &&
+		test_write_lines 1 2 3 CC 4 5 DD 6 7 8 >middle-common &&
+		test_write_lines 1 2 3 4 A B C D E F G H I J 7 8 9 >interesting &&
+		test_write_lines 1 2 3 4 X A B C 7 8 9 >evil &&
+		git add -u &&
+		git commit -m letters &&
+
+		git checkout right &&
+		test_write_lines 1 2 3 4 A X C Y E 7 8 9 >basic &&
+		test_write_lines 1 2 3 EE 4 5 FF 6 7 8 >middle-common &&
+		test_write_lines 1 2 3 4 A B C 5 6 G H I J 7 8 9 >interesting &&
+		test_write_lines 1 2 3 4 Y A B C B C 7 8 9 >evil &&
+		git add -u &&
+		git commit -m permuted
+	)
+}
+
+test_expect_success 'check zdiff3 markers' '
+	test_setup_zdiff3 &&
+	(
+		cd zdiff3 &&
+
+		git checkout left^0 &&
+
+		base=$(git rev-parse --short HEAD^1) &&
+		test_must_fail git -c merge.conflictstyle=zdiff3 merge -s recursive right^0 &&
+
+		test_write_lines 1 2 3 4 A \
+				 "<<<<<<< HEAD" B C D \
+				 "||||||| $base" 5 6 \
+				 ======= X C Y \
+				 ">>>>>>> right^0" \
+				 E 7 8 9 \
+				 >expect &&
+		test_cmp expect basic &&
+
+		test_write_lines 1 2 3 \
+				 "<<<<<<< HEAD" CC \
+				 "||||||| $base" AA \
+				 ======= EE \
+				 ">>>>>>> right^0" \
+				 4 5 \
+				 "<<<<<<< HEAD" DD \
+				 "||||||| $base" BB \
+				 ======= FF \
+				 ">>>>>>> right^0" \
+				 6 7 8 \
+				 >expect &&
+		test_cmp expect middle-common &&
+
+		test_write_lines 1 2 3 4 A B C \
+				 "<<<<<<< HEAD" D E F \
+				 "||||||| $base" 5 6 \
+				 ======= 5 6 \
+				 ">>>>>>> right^0" \
+				 G H I J 7 8 9 \
+				 >expect &&
+		test_cmp expect interesting &&
+
+		# Not passing this one yet; the common "B C" lines is still
+		# being left in the conflict blocks on the left and right
+		# sides.
+		test_write_lines 1 2 3 4 \
+				 "<<<<<<< HEAD" X A \
+				 "||||||| $base" 5 6 \
+				 ======= Y A B C \
+				 ">>>>>>> right^0" \
+				 B C 7 8 9 \
+				 >expect &&
+		test_cmp expect evil
+	)
+'
+
 test_done
diff --git a/t/t6430-merge-recursive.sh b/t/t6430-merge-recursive.sh
index a0efe7c..07067bb 100755
--- a/t/t6430-merge-recursive.sh
+++ b/t/t6430-merge-recursive.sh
@@ -706,7 +706,7 @@
 	# more trees than static slots used by oid_to_hex()
 	for commit in $c0 $c2 $c4 $c5 $c6 $c7
 	do
-		git rev-parse "$commit^{tree}"
+		git rev-parse "$commit^{tree}" || return 1
 	done >trees &&
 
 	# ignore the return code; it only fails because the input is weird...
diff --git a/t/t6600-test-reach.sh b/t/t6600-test-reach.sh
index 3d7a62d..338a9c4 100755
--- a/t/t6600-test-reach.sh
+++ b/t/t6600-test-reach.sh
@@ -32,7 +32,7 @@
 	do
 		test_commit "1-$i" &&
 		git branch -f commit-1-$i &&
-		git tag -a -m "1-$i" tag-1-$i commit-1-$i
+		git tag -a -m "1-$i" tag-1-$i commit-1-$i || return 1
 	done &&
 	for j in $(test_seq 1 9)
 	do
@@ -46,7 +46,7 @@
 		do
 			git merge commit-$j-$i -m "$x-$i" &&
 			git branch -f commit-$x-$i &&
-			git tag -a -m "$x-$i" tag-$x-$i commit-$x-$i
+			git tag -a -m "$x-$i" tag-$x-$i commit-$x-$i || return 1
 		done
 	done &&
 	git commit-graph write --reachable &&
diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
index 082be85..9aa1660 100755
--- a/t/t7004-tag.sh
+++ b/t/t7004-tag.sh
@@ -94,10 +94,10 @@
 	git log -1 \
 		--format="format:tag: tagging %h (%s, %cd)%n" \
 		--date=format:%Y-%m-%d >expected &&
-	test_when_finished "git tag -d tag_with_reflog" &&
-	git tag --create-reflog tag_with_reflog &&
-	git reflog exists refs/tags/tag_with_reflog &&
-	sed -e "s/^.*	//" .git/logs/refs/tags/tag_with_reflog >actual &&
+	test_when_finished "git tag -d tag_with_reflog1" &&
+	git tag --create-reflog tag_with_reflog1 &&
+	git reflog exists refs/tags/tag_with_reflog1 &&
+	test-tool ref-store main for-each-reflog-ent refs/tags/tag_with_reflog1 | sed -e "s/^.*	//" >actual &&
 	test_cmp expected actual
 '
 
@@ -105,10 +105,10 @@
 	git log -1 \
 		--format="format:tag: tagging %h (%s, %cd)%n" \
 		--date=format:%Y-%m-%d >expected &&
-	test_when_finished "git tag -d tag_with_reflog" &&
-	git tag -m "annotated tag" --create-reflog tag_with_reflog &&
-	git reflog exists refs/tags/tag_with_reflog &&
-	sed -e "s/^.*	//" .git/logs/refs/tags/tag_with_reflog >actual &&
+	test_when_finished "git tag -d tag_with_reflog2" &&
+	git tag -m "annotated tag" --create-reflog tag_with_reflog2 &&
+	git reflog exists refs/tags/tag_with_reflog2 &&
+	test-tool ref-store main for-each-reflog-ent refs/tags/tag_with_reflog2 | sed -e "s/^.*	//" >actual &&
 	test_cmp expected actual
 '
 
@@ -118,10 +118,10 @@
 '
 
 test_expect_success 'option core.logAllRefUpdates=always creates reflog' '
-	test_when_finished "git tag -d tag_with_reflog" &&
+	test_when_finished "git tag -d tag_with_reflog3" &&
 	test_config core.logAllRefUpdates always &&
-	git tag tag_with_reflog &&
-	git reflog exists refs/tags/tag_with_reflog
+	git tag tag_with_reflog3 &&
+	git reflog exists refs/tags/tag_with_reflog3
 '
 
 test_expect_success 'listing all tags if one exists should succeed' '
@@ -1976,9 +1976,12 @@
 committer A U Thor <author@example.com> $((1000000000 + $i * 100)) +0200
 data <<EOF
 commit #$i
-EOF"
-		test $i = 1 && echo "from refs/heads/main^0"
-		i=$(($i + 1))
+EOF" &&
+		if test $i = 1
+		then
+			echo "from refs/heads/main^0"
+		fi &&
+		i=$(($i + 1)) || return 1
 	done | git fast-import &&
 	git checkout main &&
 	git tag far-far-away HEAD^ &&
diff --git a/t/t7006-pager.sh b/t/t7006-pager.sh
index 0e7cf75..e56ca5b 100755
--- a/t/t7006-pager.sh
+++ b/t/t7006-pager.sh
@@ -661,6 +661,13 @@
 	export GIT_TRACE2_BRIEF
 '
 
+test_expect_success 'setup large log output' '
+	perl -e "
+		print \"this is a long commit message\" x 50000
+	" >commit-msg &&
+	git commit --allow-empty -F commit-msg
+'
+
 test_expect_success TTY 'git returns SIGPIPE on early pager exit' '
 	test_when_finished "rm pager-used trace.normal" &&
 	test_config core.pager ">pager-used; head -n 1; exit 0" &&
@@ -670,7 +677,7 @@
 
 	if test_have_prereq !MINGW
 	then
-		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
+		{ test_terminal git log >/dev/null; OUT=$?; } &&
 		test_match_signal 13 "$OUT"
 	else
 		test_terminal git log
@@ -691,7 +698,7 @@
 
 	if test_have_prereq !MINGW
 	then
-		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
+		{ test_terminal git log >/dev/null; OUT=$?; } &&
 		test_match_signal 13 "$OUT"
 	else
 		test_terminal git log
@@ -710,13 +717,7 @@
 	export GIT_TRACE2 &&
 	test_when_finished "unset GIT_TRACE2" &&
 
-	if test_have_prereq !MINGW
-	then
-		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
-		test "$OUT" -eq 0
-	else
-		test_terminal git log
-	fi &&
+	test_terminal git log &&
 
 	grep child_exit trace.normal >child-exits &&
 	test_line_count = 1 child-exits &&
@@ -724,41 +725,14 @@
 	test_path_is_file pager-used
 '
 
-test_expect_success TTY 'git discards nonexisting pager without SIGPIPE' '
-	test_when_finished "rm pager-used trace.normal" &&
-	test_config core.pager "wc >pager-used; does-not-exist" &&
-	GIT_TRACE2="$(pwd)/trace.normal" &&
-	export GIT_TRACE2 &&
-	test_when_finished "unset GIT_TRACE2" &&
-
-	if test_have_prereq !MINGW
-	then
-		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
-		test "$OUT" -eq 0
-	else
-		test_terminal git log
-	fi &&
-
-	grep child_exit trace.normal >child-exits &&
-	test_line_count = 1 child-exits &&
-	grep " code:127 " child-exits &&
-	test_path_is_file pager-used
-'
-
-test_expect_success TTY 'git attempts to page to nonexisting pager command, gets SIGPIPE' '
+test_expect_success TTY 'git skips paging nonexisting command' '
 	test_when_finished "rm trace.normal" &&
 	test_config core.pager "does-not-exist" &&
 	GIT_TRACE2="$(pwd)/trace.normal" &&
 	export GIT_TRACE2 &&
 	test_when_finished "unset GIT_TRACE2" &&
 
-	if test_have_prereq !MINGW
-	then
-		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
-		test_match_signal 13 "$OUT"
-	else
-		test_terminal git log
-	fi &&
+	test_terminal git log &&
 
 	grep child_exit trace.normal >child-exits &&
 	test_line_count = 1 child-exits &&
@@ -767,14 +741,14 @@
 
 test_expect_success TTY 'git returns SIGPIPE on propagated signals from pager' '
 	test_when_finished "rm pager-used trace.normal" &&
-	test_config core.pager ">pager-used; test-tool sigchain" &&
+	test_config core.pager ">pager-used; exec test-tool sigchain" &&
 	GIT_TRACE2="$(pwd)/trace.normal" &&
 	export GIT_TRACE2 &&
 	test_when_finished "unset GIT_TRACE2" &&
 
 	if test_have_prereq !MINGW
 	then
-		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
+		{ test_terminal git log >/dev/null; OUT=$?; } &&
 		test_match_signal 13 "$OUT"
 	else
 		test_terminal git log
@@ -786,4 +760,9 @@
 	test_path_is_file pager-used
 '
 
+test_expect_success TTY 'non-existent pager doesnt cause crash' '
+	test_config pager.show invalid-pager &&
+	test_terminal git show
+'
+
 test_done
diff --git a/t/t7010-setup.sh b/t/t7010-setup.sh
index 0335a9a..520f96d 100755
--- a/t/t7010-setup.sh
+++ b/t/t7010-setup.sh
@@ -137,7 +137,7 @@
 
 test_expect_success 'add a directory outside the work tree' '(
 	cd tester &&
-	d1="$(cd .. ; pwd)" &&
+	d1="$(cd .. && pwd)" &&
 	test_must_fail git add "$d1"
 )'
 
diff --git a/t/t7031-verify-tag-signed-ssh.sh b/t/t7031-verify-tag-signed-ssh.sh
index 06c9dd6..1cb36b9 100755
--- a/t/t7031-verify-tag-signed-ssh.sh
+++ b/t/t7031-verify-tag-signed-ssh.sh
@@ -48,6 +48,23 @@
 	git tag -u"${GPGSSH_KEY_UNTRUSTED}" -m eighth eighth-signed-alt
 '
 
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'create signed tags with keys having defined lifetimes' '
+	test_when_finished "test_unconfig commit.gpgsign" &&
+	test_config gpg.format ssh &&
+
+	echo expired >file && test_tick && git commit -a -m expired -S"${GPGSSH_KEY_EXPIRED}" &&
+	git tag -s -u "${GPGSSH_KEY_EXPIRED}" -m expired-signed expired-signed &&
+
+	echo notyetvalid >file && test_tick && git commit -a -m notyetvalid -S"${GPGSSH_KEY_NOTYETVALID}" &&
+	git tag -s -u "${GPGSSH_KEY_NOTYETVALID}" -m notyetvalid-signed notyetvalid-signed &&
+
+	echo timeboxedvalid >file && test_tick && git commit -a -m timeboxedvalid -S"${GPGSSH_KEY_TIMEBOXEDVALID}" &&
+	git tag -s -u "${GPGSSH_KEY_TIMEBOXEDVALID}" -m timeboxedvalid-signed timeboxedvalid-signed &&
+
+	echo timeboxedinvalid >file && test_tick && git commit -a -m timeboxedinvalid -S"${GPGSSH_KEY_TIMEBOXEDINVALID}" &&
+	git tag -s -u "${GPGSSH_KEY_TIMEBOXEDINVALID}" -m timeboxedinvalid-signed timeboxedinvalid-signed
+'
+
 test_expect_success GPGSSH 'verify and show ssh signatures' '
 	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
 	(
@@ -80,6 +97,31 @@
 	)
 '
 
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'verify-tag exits failure on expired signature key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	test_must_fail git verify-tag expired-signed 2>actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'verify-tag exits failure on not yet valid signature key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	test_must_fail git verify-tag notyetvalid-signed 2>actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'verify-tag succeeds with tag date and key validity matching' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git verify-tag timeboxedvalid-signed 2>actual &&
+	grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual &&
+	! grep "${GPGSSH_BAD_SIGNATURE}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'verify-tag failes with tag date outside of key validity' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	test_must_fail git verify-tag timeboxedinvalid-signed 2>actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
 test_expect_success GPGSSH 'detect fudged ssh signature' '
 	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
 	git cat-file tag seventh-signed >raw &&
diff --git a/t/t7064-wtstatus-pv2.sh b/t/t7064-wtstatus-pv2.sh
index eeb0534..20a0d2a 100755
--- a/t/t7064-wtstatus-pv2.sh
+++ b/t/t7064-wtstatus-pv2.sh
@@ -4,10 +4,6 @@
 
 This test exercises porcelain V2 output for git status.'
 
-
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./test-lib.sh
 
 
@@ -113,6 +109,21 @@
 	test_cmp expect actual
 '
 
+test_expect_success 'after first commit, stash existing changes' '
+	cat >expect <<-EOF &&
+	# branch.oid $H0
+	# branch.head initial-branch
+	# stash 2
+	EOF
+
+	test_when_finished "git stash pop && git stash pop" &&
+
+	git stash -- file_x &&
+	git stash &&
+	git status --porcelain=v2 --branch --show-stash --untracked-files=no >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'after first commit but omit untracked files and branch' '
 	cat >expect <<-EOF &&
 	1 .M N... 100644 100644 100644 $OID_X $OID_X file_x
diff --git a/t/t7101-reset-empty-subdirs.sh b/t/t7101-reset-empty-subdirs.sh
index 5530651..638bb04 100755
--- a/t/t7101-reset-empty-subdirs.sh
+++ b/t/t7101-reset-empty-subdirs.sh
@@ -4,6 +4,8 @@
 #
 
 test_description='git reset should cull empty subdirs'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff-data.sh
 
diff --git a/t/t7102-reset.sh b/t/t7102-reset.sh
index 601b2bf..d054260 100755
--- a/t/t7102-reset.sh
+++ b/t/t7102-reset.sh
@@ -472,6 +472,23 @@
 	test_cmp expect output
 '
 
+test_expect_success '--mixed preserves skip-worktree' '
+	echo 123 >>file2 &&
+	git add file2 &&
+	git update-index --skip-worktree file2 &&
+	git reset --mixed HEAD >output &&
+	test_must_be_empty output &&
+
+	cat >expect <<-\EOF &&
+	Unstaged changes after reset:
+	M	file2
+	EOF
+	git update-index --no-skip-worktree file2 &&
+	git add file2 &&
+	git reset --mixed HEAD >output &&
+	test_cmp expect output
+'
+
 test_expect_success 'resetting specific path that is unmerged' '
 	git rm --cached file2 &&
 	F1=$(git rev-parse HEAD:file1) &&
diff --git a/t/t7103-reset-bare.sh b/t/t7103-reset-bare.sh
index afe36a5..0de83e3 100755
--- a/t/t7103-reset-bare.sh
+++ b/t/t7103-reset-bare.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='git reset in a bare repository'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup non-bare' '
diff --git a/t/t7107-reset-pathspec-file.sh b/t/t7107-reset-pathspec-file.sh
index 15ccb14..523efbe 100755
--- a/t/t7107-reset-pathspec-file.sh
+++ b/t/t7107-reset-pathspec-file.sh
@@ -160,13 +160,13 @@
 	git rm fileA.t &&
 
 	test_must_fail git reset --pathspec-from-file=list --patch 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --patch" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--patch. cannot be used together" err &&
 
 	test_must_fail git reset --pathspec-from-file=list -- fileA.t 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with pathspec arguments" err &&
+	test_i18ngrep -e ".--pathspec-from-file. and pathspec arguments cannot be used together" err &&
 
 	test_must_fail git reset --pathspec-file-nul 2>err &&
-	test_i18ngrep -e "--pathspec-file-nul requires --pathspec-from-file" err &&
+	test_i18ngrep -e "the option .--pathspec-file-nul. requires .--pathspec-from-file." err &&
 
 	test_must_fail git reset --soft --pathspec-from-file=list 2>err &&
 	test_i18ngrep -e "fatal: Cannot do soft reset with paths" err &&
diff --git a/t/t7110-reset-merge.sh b/t/t7110-reset-merge.sh
index a82a07a..3d62e10 100755
--- a/t/t7110-reset-merge.sh
+++ b/t/t7110-reset-merge.sh
@@ -8,7 +8,7 @@
 . ./test-lib.sh
 
 test_expect_success setup '
-    for i in 1 2 3; do echo line $i; done >file1 &&
+    printf "line %d\n" 1 2 3 >file1 &&
     cat file1 >file2 &&
     git add file1 file2 &&
     test_tick &&
diff --git a/t/t7113-post-index-change-hook.sh b/t/t7113-post-index-change-hook.sh
index 688fa99..a21781d 100755
--- a/t/t7113-post-index-change-hook.sh
+++ b/t/t7113-post-index-change-hook.sh
@@ -5,6 +5,7 @@
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index b7ba1c3..61ad47b 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -658,4 +658,21 @@
 	test_cmp expect arm
 '
 
+test_expect_success 'tracking info copied with autoSetupMerge=inherit' '
+	git reset --hard main &&
+	# default config does not copy tracking info
+	git checkout -b foo-no-inherit koala/bear &&
+	test_cmp_config "" --default "" branch.foo-no-inherit.remote &&
+	test_cmp_config "" --default "" branch.foo-no-inherit.merge &&
+	# with autoSetupMerge=inherit, we copy tracking info from koala/bear
+	test_config branch.autoSetupMerge inherit &&
+	git checkout -b foo koala/bear &&
+	test_cmp_config origin branch.foo.remote &&
+	test_cmp_config refs/heads/koala/bear branch.foo.merge &&
+	# no tracking info to inherit from main
+	git checkout -b main2 main &&
+	test_cmp_config "" --default "" branch.main2.remote &&
+	test_cmp_config "" --default "" branch.main2.merge
+'
+
 test_done
diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh
index cb1b8e3..e7cec2e 100755
--- a/t/t7400-submodule-basic.sh
+++ b/t/t7400-submodule-basic.sh
@@ -1182,18 +1182,17 @@
 	rmdir init example2
 '
 
-test_expect_success 'submodule deinit fails when submodule has a .git directory even when forced' '
+test_expect_success 'submodule deinit absorbs .git directory if .git is a directory' '
 	git submodule update --init &&
 	(
 		cd init &&
 		rm .git &&
-		cp -R ../.git/modules/example .git &&
+		mv ../.git/modules/example .git &&
 		GIT_WORK_TREE=. git config --unset core.worktree
 	) &&
-	test_must_fail git submodule deinit init &&
-	test_must_fail git submodule deinit -f init &&
-	test -d init/.git &&
-	test -n "$(git config --get-regexp "submodule\.example\.")"
+	git submodule deinit init &&
+	test_path_is_missing init/.git &&
+	test -z "$(git config --get-regexp "submodule\.example\.")"
 '
 
 test_expect_success 'submodule with UTF-8 name' '
diff --git a/t/t7500-commit-template-squash-signoff.sh b/t/t7500-commit-template-squash-signoff.sh
index 8dd0f98..9196465 100755
--- a/t/t7500-commit-template-squash-signoff.sh
+++ b/t/t7500-commit-template-squash-signoff.sh
@@ -359,14 +359,14 @@
 
 test_expect_success '--fixup=reword: error out with -m option' '
 	commit_for_rebase_autosquash_setup &&
-	echo "fatal: cannot combine -m with --fixup:reword" >expect &&
+	echo "fatal: options '\''-m'\'' and '\''--fixup:reword'\'' cannot be used together" >expect &&
 	test_must_fail git commit --fixup=reword:HEAD~ -m "reword commit message" 2>actual &&
 	test_cmp expect actual
 '
 
 test_expect_success '--fixup=amend: error out with -m option' '
 	commit_for_rebase_autosquash_setup &&
-	echo "fatal: cannot combine -m with --fixup:amend" >expect &&
+	echo "fatal: options '\''-m'\'' and '\''--fixup:amend'\'' cannot be used together" >expect &&
 	test_must_fail git commit --fixup=amend:HEAD~ -m "amend commit message" 2>actual &&
 	test_cmp expect actual
 '
@@ -421,8 +421,9 @@
 
 test_fixup_reword_opt () {
 	test_expect_success "--fixup=reword: incompatible with $1" "
-		echo 'fatal: reword option of --fixup is mutually exclusive with'\
-			'--patch/--interactive/--all/--include/--only' >expect &&
+		echo 'fatal: reword option of '\''--fixup'\'' and' \
+			''\''--patch/--interactive/--all/--include/--only'\' \
+			'cannot be used together' >expect &&
 		test_must_fail git commit --fixup=reword:HEAD~ $1 2>actual &&
 		test_cmp expect actual
 	"
@@ -435,7 +436,7 @@
 
 test_expect_success '--fixup=reword: give error with pathsec' '
 	commit_for_rebase_autosquash_setup &&
-	echo "fatal: cannot combine reword option of --fixup with path '\''foo'\''" >expect &&
+	echo "fatal: reword option of '\''--fixup'\'' and path '\''foo'\'' cannot be used together" >expect &&
 	test_must_fail git commit --fixup=reword:HEAD~ -- foo 2>actual &&
 	test_cmp expect actual
 '
diff --git a/t/t7501-commit-basic-functionality.sh b/t/t7501-commit-basic-functionality.sh
index 512ae27..fb5417d 100755
--- a/t/t7501-commit-basic-functionality.sh
+++ b/t/t7501-commit-basic-functionality.sh
@@ -667,10 +667,7 @@
 
 test_expect_success 'commit a file whose name is a dash' '
 	git reset --hard &&
-	for i in 1 2 3 4 5
-	do
-		echo $i
-	done >./- &&
+	test_write_lines 1 2 3 4 5 >./- &&
 	git add ./- &&
 	test_tick &&
 	git commit -m "add dash" >output </dev/null &&
diff --git a/t/t7505-prepare-commit-msg-hook.sh b/t/t7505-prepare-commit-msg-hook.sh
index 2a07c70..e39c809 100755
--- a/t/t7505-prepare-commit-msg-hook.sh
+++ b/t/t7505-prepare-commit-msg-hook.sh
@@ -16,7 +16,7 @@
 	test_commit rebase-b b bb &&
 	for i in $(test_seq 1 13)
 	do
-		test_commit rebase-$i c $i
+		test_commit rebase-$i c $i || return 1
 	done &&
 	git checkout main &&
 
diff --git a/t/t7509-commit-authorship.sh b/t/t7509-commit-authorship.sh
index d568593..21c668f 100755
--- a/t/t7509-commit-authorship.sh
+++ b/t/t7509-commit-authorship.sh
@@ -5,6 +5,7 @@
 
 test_description='commit tests of various authorhip options. '
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 author_header () {
diff --git a/t/t7510-signed-commit.sh b/t/t7510-signed-commit.sh
index d65a017..8593b7e 100755
--- a/t/t7510-signed-commit.sh
+++ b/t/t7510-signed-commit.sh
@@ -71,25 +71,7 @@
 	git tag eleventh-signed $(cat oid) &&
 	echo 12 | git commit-tree --gpg-sign=B7227189 HEAD^{tree} >oid &&
 	test_line_count = 1 oid &&
-	git tag twelfth-signed-alt $(cat oid) &&
-
-	cat >keydetails <<-\EOF &&
-	Key-Type: RSA
-	Key-Length: 2048
-	Subkey-Type: RSA
-	Subkey-Length: 2048
-	Name-Real: Unknown User
-	Name-Email: unknown@git.com
-	Expire-Date: 0
-	%no-ask-passphrase
-	%no-protection
-	EOF
-	gpg --batch --gen-key keydetails &&
-	echo 13 >file && git commit -a -S"unknown@git.com" -m thirteenth &&
-	git tag thirteenth-signed &&
-	DELETE_FINGERPRINT=$(gpg -K --with-colons --fingerprint --batch unknown@git.com | grep "^fpr" | head -n 1 | awk -F ":" "{print \$10;}") &&
-	gpg --batch --yes --delete-secret-keys $DELETE_FINGERPRINT &&
-	gpg --batch --yes --delete-keys unknown@git.com
+	git tag twelfth-signed-alt $(cat oid)
 '
 
 test_expect_success GPG 'verify and show signatures' '
@@ -129,7 +111,7 @@
 '
 
 test_expect_success GPG 'verify-commit exits failure on unknown signature' '
-	test_must_fail git verify-commit thirteenth-signed 2>actual &&
+	test_must_fail env GNUPGHOME="$GNUPGHOME_NOT_USED" git verify-commit initial 2>actual &&
 	! grep "Good signature from" actual &&
 	! grep "BAD signature from" actual &&
 	grep -q -F -e "No public key" -e "public key not found" actual
@@ -228,7 +210,7 @@
 '
 
 test_expect_success GPG 'amending already signed commit' '
-	git checkout fourth-signed^0 &&
+	git checkout -f fourth-signed^0 &&
 	git commit --amend -S --no-edit &&
 	git verify-commit HEAD &&
 	git show -s --show-signature HEAD >actual &&
diff --git a/t/t7511-status-index.sh b/t/t7511-status-index.sh
index b5fdc04..4ffa45a 100755
--- a/t/t7511-status-index.sh
+++ b/t/t7511-status-index.sh
@@ -2,6 +2,7 @@
 
 test_description='git status with certain file name lengths'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 files="0 1 2 3 4 5 6 7 8 9 a b c d e f g h i j k l m n o p q r s t u v w x y z"
diff --git a/t/t7512-status-help.sh b/t/t7512-status-help.sh
index 7f2956d..2f16d57 100755
--- a/t/t7512-status-help.sh
+++ b/t/t7512-status-help.sh
@@ -659,6 +659,7 @@
 You are in the middle of an am session.
 The current patch is empty.
   (use "git am --skip" to skip this patch)
+  (use "git am --allow-empty" to record this patch as an empty commit)
   (use "git am --abort" to restore the original branch)
 
 nothing to commit (use -u to show untracked files)
diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
index 04885d0..97f1090 100755
--- a/t/t7513-interpret-trailers.sh
+++ b/t/t7513-interpret-trailers.sh
@@ -156,7 +156,7 @@
 		Acked-by: Johan
 		Reviewed-by: Peff
 	EOF
-	{ echo; echo "Acked-by: Johan"; } |
+	{ echo && echo "Acked-by: Johan"; } |
 	git -c "trailer.Acked-by.ifexists=addifdifferent" interpret-trailers \
 		--trailer "Reviewed-by: Peff" --trailer "Acked-by: Johan" >actual &&
 	test_cmp expected actual
diff --git a/t/t7515-status-symlinks.sh b/t/t7515-status-symlinks.sh
index 9f989be..e3d6bb6 100755
--- a/t/t7515-status-symlinks.sh
+++ b/t/t7515-status-symlinks.sh
@@ -2,6 +2,7 @@
 
 test_description='git status and symlinks'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t7519-status-fsmonitor.sh b/t/t7519-status-fsmonitor.sh
index f488d93..a6308ac 100755
--- a/t/t7519-status-fsmonitor.sh
+++ b/t/t7519-status-fsmonitor.sh
@@ -248,7 +248,7 @@
 		git config core.preloadIndex $preload_val &&
 		if test $preload_val = true
 		then
-			GIT_TEST_PRELOAD_INDEX=$preload_val; export GIT_TEST_PRELOAD_INDEX
+			GIT_TEST_PRELOAD_INDEX=$preload_val && export GIT_TEST_PRELOAD_INDEX
 		else
 			sane_unset GIT_TEST_PRELOAD_INDEX
 		fi
@@ -390,7 +390,7 @@
 # during a call to 'git status'. Otherwise, we verify that we _do_ call it.
 check_sparse_index_behavior () {
 	git -C full status --porcelain=v2 >expect &&
-	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
 		git -C sparse status --porcelain=v2 >actual &&
 	test_region $1 index ensure_full_index trace2.txt &&
 	test_region fsm_hook query trace2.txt &&
diff --git a/t/t7525-status-rename.sh b/t/t7525-status-rename.sh
index a62736d..22bf5c7 100755
--- a/t/t7525-status-rename.sh
+++ b/t/t7525-status-rename.sh
@@ -2,6 +2,7 @@
 
 test_description='git status rename detection options'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t7526-commit-pathspec-file.sh b/t/t7526-commit-pathspec-file.sh
index 5fbe47e..ad011bb 100755
--- a/t/t7526-commit-pathspec-file.sh
+++ b/t/t7526-commit-pathspec-file.sh
@@ -2,6 +2,7 @@
 
 test_description='commit --pathspec-from-file'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_tick
@@ -140,19 +141,19 @@
 	>empty_list &&
 
 	test_must_fail git commit --pathspec-from-file=list --interactive -m "Commit" 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --interactive/--patch" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--interactive/--patch. cannot be used together" err &&
 
 	test_must_fail git commit --pathspec-from-file=list --patch -m "Commit" 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with --interactive/--patch" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .--interactive/--patch. cannot be used together" err &&
 
 	test_must_fail git commit --pathspec-from-file=list --all -m "Commit" 2>err &&
-	test_i18ngrep -e "--pathspec-from-file with -a does not make sense" err &&
+	test_i18ngrep -e "options .--pathspec-from-file. and .-a. cannot be used together" err &&
 
 	test_must_fail git commit --pathspec-from-file=list -m "Commit" -- fileA.t 2>err &&
-	test_i18ngrep -e "--pathspec-from-file is incompatible with pathspec arguments" err &&
+	test_i18ngrep -e ".--pathspec-from-file. and pathspec arguments cannot be used together" err &&
 
 	test_must_fail git commit --pathspec-file-nul -m "Commit" 2>err &&
-	test_i18ngrep -e "--pathspec-file-nul requires --pathspec-from-file" err &&
+	test_i18ngrep -e "the option .--pathspec-file-nul. requires .--pathspec-from-file." err &&
 
 	test_must_fail git commit --pathspec-from-file=empty_list --include -m "Commit" 2>err &&
 	test_i18ngrep -e "No paths with --include/--only does not make sense." err &&
diff --git a/t/t7528-signed-commit-ssh.sh b/t/t7528-signed-commit-ssh.sh
index badf3ed..f47e995 100755
--- a/t/t7528-signed-commit-ssh.sh
+++ b/t/t7528-signed-commit-ssh.sh
@@ -73,7 +73,46 @@
 	git tag eleventh-signed $(cat oid) &&
 	echo 12 | git commit-tree --gpg-sign="${GPGSSH_KEY_UNTRUSTED}" HEAD^{tree} >oid &&
 	test_line_count = 1 oid &&
-	git tag twelfth-signed-alt $(cat oid)
+	git tag twelfth-signed-alt $(cat oid) &&
+
+	echo 13>file && test_tick && git commit -a -m thirteenth -S"${GPGSSH_KEY_ECDSA}" &&
+	git tag thirteenth-signed-ecdsa
+'
+
+test_expect_success GPGSSH 'sign commits using literal public keys with ssh-agent' '
+	test_when_finished "test_unconfig commit.gpgsign" &&
+	test_config gpg.format ssh &&
+	eval $(ssh-agent) &&
+	test_when_finished "kill ${SSH_AGENT_PID}" &&
+	ssh-add "${GPGSSH_KEY_PRIMARY}" &&
+	echo 1 >file && git add file &&
+	git commit -a -m rsa-inline -S"$(cat "${GPGSSH_KEY_PRIMARY}.pub")" &&
+	echo 2 >file &&
+	test_config user.signingkey "$(cat "${GPGSSH_KEY_PRIMARY}.pub")" &&
+	git commit -a -m rsa-config -S &&
+	ssh-add "${GPGSSH_KEY_ECDSA}" &&
+	echo 3 >file &&
+	git commit -a -m ecdsa-inline -S"key::$(cat "${GPGSSH_KEY_ECDSA}.pub")" &&
+	echo 4 >file &&
+	test_config user.signingkey "key::$(cat "${GPGSSH_KEY_ECDSA}.pub")" &&
+	git commit -a -m ecdsa-config -S
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'create signed commits with keys having defined lifetimes' '
+	test_when_finished "test_unconfig commit.gpgsign" &&
+	test_config gpg.format ssh &&
+
+	echo expired >file && test_tick && git commit -a -m expired -S"${GPGSSH_KEY_EXPIRED}" &&
+	git tag expired-signed &&
+
+	echo notyetvalid >file && test_tick && git commit -a -m notyetvalid -S"${GPGSSH_KEY_NOTYETVALID}" &&
+	git tag notyetvalid-signed &&
+
+	echo timeboxedvalid >file && test_tick && git commit -a -m timeboxedvalid -S"${GPGSSH_KEY_TIMEBOXEDVALID}" &&
+	git tag timeboxedvalid-signed &&
+
+	echo timeboxedinvalid >file && test_tick && git commit -a -m timeboxedinvalid -S"${GPGSSH_KEY_TIMEBOXEDINVALID}" &&
+	git tag timeboxedinvalid-signed
 '
 
 test_expect_success GPGSSH 'verify and show signatures' '
@@ -122,6 +161,31 @@
 	grep "${GPGSSH_KEY_NOT_TRUSTED}" actual
 '
 
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'verify-commit exits failure on expired signature key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	test_must_fail git verify-commit expired-signed 2>actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'verify-commit exits failure on not yet valid signature key' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	test_must_fail git verify-commit notyetvalid-signed 2>actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'verify-commit succeeds with commit date and key validity matching' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	git verify-commit timeboxedvalid-signed 2>actual &&
+	grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual &&
+	! grep "${GPGSSH_BAD_SIGNATURE}" actual
+'
+
+test_expect_success GPGSSH,GPGSSH_VERIFYTIME 'verify-commit exits failure with commit date outside of key validity' '
+	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
+	test_must_fail git verify-commit timeboxedinvalid-signed 2>actual &&
+	! grep "${GPGSSH_GOOD_SIGNATURE_TRUSTED}" actual
+'
+
 test_expect_success GPGSSH 'verify-commit exits success with matching minTrustLevel' '
 	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
 	test_config gpg.minTrustLevel fully &&
@@ -217,7 +281,7 @@
 	test_config gpg.format ssh &&
 	test_config user.signingkey "${GPGSSH_KEY_PRIMARY}" &&
 	test_config gpg.ssh.allowedSignersFile "${GPGSSH_ALLOWED_SIGNERS}" &&
-	git checkout fourth-signed^0 &&
+	git checkout -f fourth-signed^0 &&
 	git commit --amend -S --no-edit &&
 	git verify-commit HEAD &&
 	git show -s --show-signature HEAD >actual &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index c773e30..f0f6fda 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -967,7 +967,7 @@
 	# 256 near-identical stanzas...
 	for i in $(test_seq 1 256); do
 		for j in 1 2 3 4 5; do
-			echo $i-$j
+			echo $i-$j || return 1
 		done
 	done >file &&
 	git add file &&
diff --git a/t/t7602-merge-octopus-many.sh b/t/t7602-merge-octopus-many.sh
index a9c816b..ff085b0 100755
--- a/t/t7602-merge-octopus-many.sh
+++ b/t/t7602-merge-octopus-many.sh
@@ -29,8 +29,8 @@
 	refs="" &&
 	while test $i -le 30
 	do
-		refs="$refs c$i"
-		i=$(expr $i + 1)
+		refs="$refs c$i" &&
+		i=$(expr $i + 1) || return 1
 	done &&
 	git merge $refs &&
 	test "$(git rev-parse c1)" != "$(git rev-parse HEAD)" &&
diff --git a/t/t7603-merge-reduce-heads.sh b/t/t7603-merge-reduce-heads.sh
index 27cd94a..4887ca7 100755
--- a/t/t7603-merge-reduce-heads.sh
+++ b/t/t7603-merge-reduce-heads.sh
@@ -95,7 +95,7 @@
 		echo $i > $i.c &&
 		git add $i.c &&
 		git commit -m $i &&
-		git tag $i
+		git tag $i || return 1
 	done &&
 	git reset --hard A &&
 	for i in F G H I
@@ -103,7 +103,7 @@
 		echo $i > $i.c &&
 		git add $i.c &&
 		git commit -m $i &&
-		git tag $i
+		git tag $i || return 1
 	done
 '
 
diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 0260ad6..e489869 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -5,6 +5,7 @@
 . ./test-lib.sh
 . "${TEST_DIRECTORY}/lib-bitmap.sh"
 . "${TEST_DIRECTORY}/lib-midx.sh"
+. "${TEST_DIRECTORY}/lib-terminal.sh"
 
 commit_and_pack () {
 	test_commit "$@" 1>&2 &&
@@ -117,7 +118,7 @@
 			rm alt_objects/pack/$base_name.keep
 		else
 			touch alt_objects/pack/$base_name.keep
-		fi
+		fi || return 1
 	done &&
 	git repack -a -d &&
 	test_no_missing_in_packs
@@ -372,4 +373,16 @@
 	)
 '
 
+test_expect_success '--write-midx -b packs non-kept objects' '
+	GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
+		git repack --write-midx -a -b &&
+	test_subcommand_inexact git pack-objects --honor-pack-keep <trace.txt
+'
+
+test_expect_success TTY '--quiet disables progress' '
+	test_terminal env GIT_PROGRESS_DELAY=0 \
+		git -C midx repack -ad --quiet --write-midx 2>stderr &&
+	test_must_be_empty stderr
+'
+
 test_done
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index 6b6423a..424c31c 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -31,28 +31,28 @@
 EOF
 
 test_expect_success setup '
-	{
-		echo foo mmap bar
-		echo foo_mmap bar
-		echo foo_mmap bar mmap
-		echo foo mmap bar_mmap
-		echo foo_mmap bar mmap baz
-	} >file &&
-	{
-		echo Hello world
-		echo HeLLo world
-		echo Hello_world
-		echo HeLLo_world
-	} >hello_world &&
-	{
-		echo "a+b*c"
-		echo "a+bc"
-		echo "abc"
-	} >ab &&
-	{
-		echo d &&
-		echo 0
-	} >d0 &&
+	cat >file <<-\EOF &&
+	foo mmap bar
+	foo_mmap bar
+	foo_mmap bar mmap
+	foo mmap bar_mmap
+	foo_mmap bar mmap baz
+	EOF
+	cat >hello_world <<-\EOF &&
+	Hello world
+	HeLLo world
+	Hello_world
+	HeLLo_world
+	EOF
+	cat >ab <<-\EOF &&
+	a+b*c
+	a+bc
+	abc
+	EOF
+	cat >d0 <<-\EOF &&
+	d
+	0
+	EOF
 	echo vvv >v &&
 	echo ww w >w &&
 	echo x x xx x >x &&
@@ -63,13 +63,13 @@
 	echo vvv >t/v &&
 	mkdir t/a &&
 	echo vvv >t/a/v &&
-	{
-		echo "line without leading space1"
-		echo " line with leading space1"
-		echo " line with leading space2"
-		echo " line with leading space3"
-		echo "line without leading space2"
-	} >space &&
+	qz_to_tab_space >space <<-\EOF &&
+	line without leading space1
+	Zline with leading space1
+	Zline with leading space2
+	Zline with leading space3
+	line without leading space2
+	EOF
 	cat >hello.ps1 <<-\EOF &&
 	# No-op.
 	function dummy() {}
@@ -106,129 +106,129 @@
 	esac
 
 	test_expect_success "grep -w $L" '
-		{
-			echo ${HC}file:1:foo mmap bar
-			echo ${HC}file:3:foo_mmap bar mmap
-			echo ${HC}file:4:foo mmap bar_mmap
-			echo ${HC}file:5:foo_mmap bar mmap baz
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:1:foo mmap bar
+		${HC}file:3:foo_mmap bar mmap
+		${HC}file:4:foo mmap bar_mmap
+		${HC}file:5:foo_mmap bar mmap baz
+		EOF
 		git -c grep.linenumber=false grep -n -w -e mmap $H >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep -w $L (with --column)" '
-		{
-			echo ${HC}file:5:foo mmap bar
-			echo ${HC}file:14:foo_mmap bar mmap
-			echo ${HC}file:5:foo mmap bar_mmap
-			echo ${HC}file:14:foo_mmap bar mmap baz
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:5:foo mmap bar
+		${HC}file:14:foo_mmap bar mmap
+		${HC}file:5:foo mmap bar_mmap
+		${HC}file:14:foo_mmap bar mmap baz
+		EOF
 		git grep --column -w -e mmap $H >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep -w $L (with --column, extended OR)" '
-		{
-			echo ${HC}file:14:foo_mmap bar mmap
-			echo ${HC}file:19:foo_mmap bar mmap baz
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:14:foo_mmap bar mmap
+		${HC}file:19:foo_mmap bar mmap baz
+		EOF
 		git grep --column -w -e mmap$ --or -e baz $H >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep -w $L (with --column, --invert-match)" '
-		{
-			echo ${HC}file:1:foo mmap bar
-			echo ${HC}file:1:foo_mmap bar
-			echo ${HC}file:1:foo_mmap bar mmap
-			echo ${HC}file:1:foo mmap bar_mmap
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:1:foo mmap bar
+		${HC}file:1:foo_mmap bar
+		${HC}file:1:foo_mmap bar mmap
+		${HC}file:1:foo mmap bar_mmap
+		EOF
 		git grep --column --invert-match -w -e baz $H -- file >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep $L (with --column, --invert-match, extended OR)" '
-		{
-			echo ${HC}hello_world:6:HeLLo_world
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}hello_world:6:HeLLo_world
+		EOF
 		git grep --column --invert-match -e ll --or --not -e _ $H -- hello_world \
 			>actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep $L (with --column, --invert-match, extended AND)" '
-		{
-			echo ${HC}hello_world:3:Hello world
-			echo ${HC}hello_world:3:Hello_world
-			echo ${HC}hello_world:6:HeLLo_world
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}hello_world:3:Hello world
+		${HC}hello_world:3:Hello_world
+		${HC}hello_world:6:HeLLo_world
+		EOF
 		git grep --column --invert-match --not -e _ --and --not -e ll $H -- hello_world \
 			>actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep $L (with --column, double-negation)" '
-		{
-			echo ${HC}file:1:foo_mmap bar mmap baz
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:1:foo_mmap bar mmap baz
+		EOF
 		git grep --column --not \( --not -e foo --or --not -e baz \) $H -- file \
 			>actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep -w $L (with --column, -C)" '
-		{
-			echo ${HC}file:5:foo mmap bar
-			echo ${HC}file-foo_mmap bar
-			echo ${HC}file:14:foo_mmap bar mmap
-			echo ${HC}file:5:foo mmap bar_mmap
-			echo ${HC}file:14:foo_mmap bar mmap baz
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:5:foo mmap bar
+		${HC}file-foo_mmap bar
+		${HC}file:14:foo_mmap bar mmap
+		${HC}file:5:foo mmap bar_mmap
+		${HC}file:14:foo_mmap bar mmap baz
+		EOF
 		git grep --column -w -C1 -e mmap $H >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep -w $L (with --line-number, --column)" '
-		{
-			echo ${HC}file:1:5:foo mmap bar
-			echo ${HC}file:3:14:foo_mmap bar mmap
-			echo ${HC}file:4:5:foo mmap bar_mmap
-			echo ${HC}file:5:14:foo_mmap bar mmap baz
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:1:5:foo mmap bar
+		${HC}file:3:14:foo_mmap bar mmap
+		${HC}file:4:5:foo mmap bar_mmap
+		${HC}file:5:14:foo_mmap bar mmap baz
+		EOF
 		git grep -n --column -w -e mmap $H >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep -w $L (with non-extended patterns, --column)" '
-		{
-			echo ${HC}file:5:foo mmap bar
-			echo ${HC}file:10:foo_mmap bar
-			echo ${HC}file:10:foo_mmap bar mmap
-			echo ${HC}file:5:foo mmap bar_mmap
-			echo ${HC}file:10:foo_mmap bar mmap baz
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:5:foo mmap bar
+		${HC}file:10:foo_mmap bar
+		${HC}file:10:foo_mmap bar mmap
+		${HC}file:5:foo mmap bar_mmap
+		${HC}file:10:foo_mmap bar mmap baz
+		EOF
 		git grep --column -w -e bar -e mmap $H >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep -w $L" '
-		{
-			echo ${HC}file:1:foo mmap bar
-			echo ${HC}file:3:foo_mmap bar mmap
-			echo ${HC}file:4:foo mmap bar_mmap
-			echo ${HC}file:5:foo_mmap bar mmap baz
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:1:foo mmap bar
+		${HC}file:3:foo_mmap bar mmap
+		${HC}file:4:foo mmap bar_mmap
+		${HC}file:5:foo_mmap bar mmap baz
+		EOF
 		git -c grep.linenumber=true grep -w -e mmap $H >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep -w $L" '
-		{
-			echo ${HC}file:foo mmap bar
-			echo ${HC}file:foo_mmap bar mmap
-			echo ${HC}file:foo mmap bar_mmap
-			echo ${HC}file:foo_mmap bar mmap baz
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:foo mmap bar
+		${HC}file:foo_mmap bar mmap
+		${HC}file:foo mmap bar_mmap
+		${HC}file:foo_mmap bar mmap baz
+		EOF
 		git -c grep.linenumber=true grep --no-line-number -w -e mmap $H >actual &&
 		test_cmp expected actual
 	'
@@ -239,17 +239,17 @@
 	'
 
 	test_expect_success "grep -w $L (x)" '
-		{
-			echo ${HC}x:1:x x xx x
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}x:1:x x xx x
+		EOF
 		git grep -n -w -e "x xx* x" $H >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep -w $L (y-1)" '
-		{
-			echo ${HC}y:1:y yy
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}y:1:y yy
+		EOF
 		git grep -n -w -e "^y" $H >actual &&
 		test_cmp expected actual
 	'
@@ -277,16 +277,16 @@
 	'
 
 	test_expect_success "grep $L (with --column, --only-matching)" '
-		{
-			echo ${HC}file:1:5:mmap
-			echo ${HC}file:2:5:mmap
-			echo ${HC}file:3:5:mmap
-			echo ${HC}file:3:13:mmap
-			echo ${HC}file:4:5:mmap
-			echo ${HC}file:4:13:mmap
-			echo ${HC}file:5:5:mmap
-			echo ${HC}file:5:13:mmap
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}file:1:5:mmap
+		${HC}file:2:5:mmap
+		${HC}file:3:5:mmap
+		${HC}file:3:13:mmap
+		${HC}file:4:5:mmap
+		${HC}file:4:13:mmap
+		${HC}file:5:5:mmap
+		${HC}file:5:13:mmap
+		EOF
 		git grep --column -n -o -e mmap $H >actual &&
 		test_cmp expected actual
 	'
@@ -320,11 +320,11 @@
 	'
 
 	test_expect_success "grep --max-depth -1 $L" '
-		{
-			echo ${HC}t/a/v:1:vvv
-			echo ${HC}t/v:1:vvv
-			echo ${HC}v:1:vvv
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}t/a/v:1:vvv
+		${HC}t/v:1:vvv
+		${HC}v:1:vvv
+		EOF
 		git grep --max-depth -1 -n -e vvv $H >actual &&
 		test_cmp expected actual &&
 		git grep --recursive -n -e vvv $H >actual &&
@@ -332,9 +332,9 @@
 	'
 
 	test_expect_success "grep --max-depth 0 $L" '
-		{
-			echo ${HC}v:1:vvv
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}v:1:vvv
+		EOF
 		git grep --max-depth 0 -n -e vvv $H >actual &&
 		test_cmp expected actual &&
 		git grep --no-recursive -n -e vvv $H >actual &&
@@ -342,11 +342,11 @@
 	'
 
 	test_expect_success "grep --max-depth 0 -- '*' $L" '
-		{
-			echo ${HC}t/a/v:1:vvv
-			echo ${HC}t/v:1:vvv
-			echo ${HC}v:1:vvv
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}t/a/v:1:vvv
+		${HC}t/v:1:vvv
+		${HC}v:1:vvv
+		EOF
 		git grep --max-depth 0 -n -e vvv $H -- "*" >actual &&
 		test_cmp expected actual &&
 		git grep --no-recursive -n -e vvv $H -- "*" >actual &&
@@ -354,18 +354,18 @@
 	'
 
 	test_expect_success "grep --max-depth 1 $L" '
-		{
-			echo ${HC}t/v:1:vvv
-			echo ${HC}v:1:vvv
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}t/v:1:vvv
+		${HC}v:1:vvv
+		EOF
 		git grep --max-depth 1 -n -e vvv $H >actual &&
 		test_cmp expected actual
 	'
 
 	test_expect_success "grep --max-depth 0 -- t $L" '
-		{
-			echo ${HC}t/v:1:vvv
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}t/v:1:vvv
+		EOF
 		git grep --max-depth 0 -n -e vvv $H -- t >actual &&
 		test_cmp expected actual &&
 		git grep --no-recursive -n -e vvv $H -- t >actual &&
@@ -373,10 +373,10 @@
 	'
 
 	test_expect_success "grep --max-depth 0 -- . t $L" '
-		{
-			echo ${HC}t/v:1:vvv
-			echo ${HC}v:1:vvv
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}t/v:1:vvv
+		${HC}v:1:vvv
+		EOF
 		git grep --max-depth 0 -n -e vvv $H -- . t >actual &&
 		test_cmp expected actual &&
 		git grep --no-recursive -n -e vvv $H -- . t >actual &&
@@ -384,10 +384,10 @@
 	'
 
 	test_expect_success "grep --max-depth 0 -- t . $L" '
-		{
-			echo ${HC}t/v:1:vvv
-			echo ${HC}v:1:vvv
-		} >expected &&
+		cat >expected <<-EOF &&
+		${HC}t/v:1:vvv
+		${HC}v:1:vvv
+		EOF
 		git grep --max-depth 0 -n -e vvv $H -- t . >actual &&
 		test_cmp expected actual &&
 		git grep --no-recursive -n -e vvv $H -- t . >actual &&
@@ -1314,10 +1314,10 @@
 '
 
 test_expect_success PCRE 'grep -P -v pattern' '
-	{
-		echo "ab:a+b*c"
-		echo "ab:a+bc"
-	} >expected &&
+	cat >expected <<-\EOF &&
+	ab:a+b*c
+	ab:a+bc
+	EOF
 	git grep -P -v "abc" ab >actual &&
 	test_cmp expected actual
 '
@@ -1331,10 +1331,10 @@
 '
 
 test_expect_success PCRE 'grep -P -w pattern' '
-	{
-		echo "hello_world:Hello world"
-		echo "hello_world:HeLLo world"
-	} >expected &&
+	cat >expected <<-\EOF &&
+	hello_world:Hello world
+	hello_world:HeLLo world
+	EOF
 	git grep -P -w "He((?i)ll)o" hello_world >actual &&
 	test_cmp expected actual
 '
@@ -1469,10 +1469,10 @@
 '
 
 test_expect_success 'grep -G pattern with grep.patternType=fixed' '
-	{
-		echo "ab:a+b*c"
-		echo "ab:a+bc"
-	} >expected &&
+	cat >expected <<-\EOF &&
+	ab:a+b*c
+	ab:a+bc
+	EOF
 	git \
 		-c grep.patterntype=fixed \
 		grep -G "a+b" ab >actual &&
@@ -1480,11 +1480,11 @@
 '
 
 test_expect_success 'grep -E pattern with grep.patternType=fixed' '
-	{
-		echo "ab:a+b*c"
-		echo "ab:a+bc"
-		echo "ab:abc"
-	} >expected &&
+	cat >expected <<-\EOF &&
+	ab:a+b*c
+	ab:a+bc
+	ab:abc
+	EOF
 	git \
 		-c grep.patterntype=fixed \
 		grep -E "a+" ab >actual &&
diff --git a/t/t7812-grep-icase-non-ascii.sh b/t/t7812-grep-icase-non-ascii.sh
index e5d1e4e..ca3f24f 100755
--- a/t/t7812-grep-icase-non-ascii.sh
+++ b/t/t7812-grep-icase-non-ascii.sh
@@ -123,4 +123,10 @@
 	test_cmp invalid-0xe5 actual
 '
 
+test_expect_success GETTEXT_LOCALE,LIBPCRE2 'PCRE v2: grep non-literal ASCII from UTF-8' '
+	git grep --perl-regexp -h -o -e ll. file >actual &&
+	echo "lló" >expected &&
+	test_cmp expected actual
+'
+
 test_done
diff --git a/t/t7815-grep-binary.sh b/t/t7815-grep-binary.sh
index 90ebb64..ac87128 100755
--- a/t/t7815-grep-binary.sh
+++ b/t/t7815-grep-binary.sh
@@ -2,6 +2,7 @@
 
 test_description='git grep in binary files'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' "
diff --git a/t/t8002-blame.sh b/t/t8002-blame.sh
index 5bb302b..ee4fdd8 100755
--- a/t/t8002-blame.sh
+++ b/t/t8002-blame.sh
@@ -97,7 +97,7 @@
 	test_commit abbrev &&
 	sha1=$(git rev-parse --verify HEAD) &&
 	check_abbrev () {
-		expect=$1; shift
+		expect=$1 && shift &&
 		echo $sha1 | cut -c 1-$expect >expect &&
 		git blame "$@" abbrev.t >actual &&
 		perl -lne "/[0-9a-f]+/ and print \$&" <actual >actual.sha &&
diff --git a/t/t8003-blame-corner-cases.sh b/t/t8003-blame-corner-cases.sh
index da80f81..d751d48 100755
--- a/t/t8003-blame-corner-cases.sh
+++ b/t/t8003-blame-corner-cases.sh
@@ -13,14 +13,8 @@
 	echo B B B B B >two &&
 	echo C C C C C >tres &&
 	echo ABC >mouse &&
-	for i in 1 2 3 4 5 6 7 8 9
-	do
-		echo $i
-	done >nine_lines &&
-	for i in 1 2 3 4 5 6 7 8 9 a
-	do
-		echo $i
-	done >ten_lines &&
+	test_write_lines 1 2 3 4 5 6 7 8 9 >nine_lines &&
+	test_write_lines 1 2 3 4 5 6 7 8 9 a >ten_lines &&
 	git add one two tres mouse nine_lines ten_lines &&
 	test_tick &&
 	GIT_AUTHOR_NAME=Initial git commit -m Initial &&
diff --git a/t/t8014-blame-ignore-fuzzy.sh b/t/t8014-blame-ignore-fuzzy.sh
index e68e611..0bd0341 100755
--- a/t/t8014-blame-ignore-fuzzy.sh
+++ b/t/t8014-blame-ignore-fuzzy.sh
@@ -310,7 +310,7 @@
 			echo "$line" >>"$i" &&
 			git add "$i" &&
 			test_tick &&
-			GIT_AUTHOR_NAME="$line_count" git commit -m "$line_count"
+			GIT_AUTHOR_NAME="$line_count" git commit -m "$line_count" || return 1
 		done <"a$i"
 	done &&
 
@@ -318,7 +318,7 @@
 	do
 		# Overwrite the files with the final content.
 		cp b$i $i &&
-		git add $i
+		git add $i || return 1
 	done &&
 	test_tick &&
 
diff --git a/t/t9102-git-svn-deep-rmdir.sh b/t/t9102-git-svn-deep-rmdir.sh
index 66cd511..7b2049c 100755
--- a/t/t9102-git-svn-deep-rmdir.sh
+++ b/t/t9102-git-svn-deep-rmdir.sh
@@ -1,5 +1,7 @@
 #!/bin/sh
 test_description='git svn rmdir'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./lib-git-svn.sh
 
 test_expect_success 'initialize repo' '
diff --git a/t/t9104-git-svn-follow-parent.sh b/t/t9104-git-svn-follow-parent.sh
index 67eed2f..c7d8e0b 100755
--- a/t/t9104-git-svn-follow-parent.sh
+++ b/t/t9104-git-svn-follow-parent.sh
@@ -117,7 +117,7 @@
 	mkdir -p import/trunk/subversion/bindings/swig/perl/t &&
 	for i in a b c ; do \
 	  echo $i > import/trunk/subversion/bindings/swig/perl/$i.pm &&
-	  echo _$i > import/trunk/subversion/bindings/swig/perl/t/$i.t; \
+	  echo _$i > import/trunk/subversion/bindings/swig/perl/t/$i.t || return 1
 	done &&
 	  echo "bad delete test" > \
 	   import/trunk/subversion/bindings/swig/perl/t/larger-parent &&
@@ -134,7 +134,7 @@
 		svn mv t native/t &&
 		for i in a b c
 		do
-			svn mv $i.pm native/$i.pm
+			svn mv $i.pm native/$i.pm || return 1
 		done &&
 		echo z >>native/t/c.t &&
 		poke native/t/c.t &&
diff --git a/t/t9107-git-svn-migrate.sh b/t/t9107-git-svn-migrate.sh
index ceaa5ba..aa908bb 100755
--- a/t/t9107-git-svn-migrate.sh
+++ b/t/t9107-git-svn-migrate.sh
@@ -98,10 +98,10 @@
 	rm -rf "$GIT_DIR"/svn &&
 	for i in $(cat fetch.out)
 	do
-		path=$(expr $i : "\([^:]*\):.*$")
-		ref=$(expr $i : "[^:]*:\(refs/remotes/.*\)$")
-		if test -z "$ref"; then continue; fi
-		if test -n "$path"; then path="/$path"; fi
+		path=${i%%:*} &&
+		ref=${i#*:} &&
+		if test "$ref" = "${ref#refs/remotes/}"; then continue; fi &&
+		if test -n "$path"; then path="/$path"; fi &&
 		mkdir -p "$GIT_DIR"/svn/$ref/info/ &&
 		echo "$svnrepo"$path >"$GIT_DIR"/svn/$ref/info/url ||
 		return 1
diff --git a/t/t9123-git-svn-rebuild-with-rewriteroot.sh b/t/t9123-git-svn-rebuild-with-rewriteroot.sh
index ead4045..3320b1f 100755
--- a/t/t9123-git-svn-rebuild-with-rewriteroot.sh
+++ b/t/t9123-git-svn-rebuild-with-rewriteroot.sh
@@ -5,6 +5,7 @@
 
 test_description='git svn respects rewriteRoot during rebuild'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./lib-git-svn.sh
 
 mkdir import
diff --git a/t/t9128-git-svn-cmd-branch.sh b/t/t9128-git-svn-cmd-branch.sh
index 4e95f79..9871f5a 100755
--- a/t/t9128-git-svn-cmd-branch.sh
+++ b/t/t9128-git-svn-cmd-branch.sh
@@ -4,6 +4,8 @@
 #
 
 test_description='git svn partial-rebuild tests'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./lib-git-svn.sh
 
 test_expect_success 'initialize svnrepo' '
diff --git a/t/t9130-git-svn-authors-file.sh b/t/t9130-git-svn-authors-file.sh
index cb764bc..90325db 100755
--- a/t/t9130-git-svn-authors-file.sh
+++ b/t/t9130-git-svn-authors-file.sh
@@ -15,7 +15,7 @@
 test_expect_success 'setup svnrepo' '
 	for i in aa bb cc dd
 	do
-		svn_cmd mkdir -m $i --username $i "$svnrepo"/$i
+		svn_cmd mkdir -m $i --username $i "$svnrepo"/$i || return 1
 	done
 	'
 
@@ -59,8 +59,8 @@
 	git svn clone --authors-file=svn-authors -s "$svnrepo"/aa aa-work &&
 	for i in bb ee cc
 	do
-		branch="aa/branches/$i"
-		svn_cmd mkdir -m "$branch" --username $i "$svnrepo/$branch"
+		branch="aa/branches/$i" &&
+		svn_cmd mkdir -m "$branch" --username $i "$svnrepo/$branch" || return 1
 	done
 	'
 
diff --git a/t/t9134-git-svn-ignore-paths.sh b/t/t9134-git-svn-ignore-paths.sh
index fff49c4..4a77eb9 100755
--- a/t/t9134-git-svn-ignore-paths.sh
+++ b/t/t9134-git-svn-ignore-paths.sh
@@ -27,7 +27,7 @@
 test_expect_success 'clone an SVN repository with ignored www directory' '
 	git svn clone --ignore-paths="^www" "$svnrepo" g &&
 	echo test_qqq > expect &&
-	for i in g/*/*.txt; do cat $i >> expect2; done &&
+	for i in g/*/*.txt; do cat $i >> expect2 || return 1; done &&
 	test_cmp expect expect2
 '
 
@@ -36,7 +36,7 @@
 	( cd c && git svn fetch --ignore-paths="^www" ) &&
 	rm expect2 &&
 	echo test_qqq > expect &&
-	for i in c/*/*.txt; do cat $i >> expect2; done &&
+	for i in c/*/*.txt; do cat $i >> expect2 || return 1; done &&
 	test_cmp expect expect2
 '
 
@@ -62,7 +62,7 @@
 		cd g &&
 		git svn rebase &&
 		printf "test_qqq\nb\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -73,7 +73,7 @@
 		cd c &&
 		git svn rebase --ignore-paths="^www" &&
 		printf "test_qqq\nb\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -94,7 +94,7 @@
 		cd g &&
 		git svn rebase &&
 		printf "test_qqq\nb\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -105,7 +105,7 @@
 		cd c &&
 		git svn rebase --ignore-paths="^www" &&
 		printf "test_qqq\nb\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -127,7 +127,7 @@
 		cd g &&
 		git svn rebase &&
 		printf "test_qqq\nb\nygg\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -138,7 +138,7 @@
 		cd c &&
 		git svn rebase --ignore-paths="^www" &&
 		printf "test_qqq\nb\nygg\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
diff --git a/t/t9138-git-svn-authors-prog.sh b/t/t9138-git-svn-authors-prog.sh
index 027b416..784ec7f 100755
--- a/t/t9138-git-svn-authors-prog.sh
+++ b/t/t9138-git-svn-authors-prog.sh
@@ -27,7 +27,7 @@
 test_expect_success 'setup svnrepo' '
 	for i in aa bb cc-sub dd-sub ee-foo ff
 	do
-		svn mkdir -m $i --username $i "$svnrepo"/$i
+		svn mkdir -m $i --username $i "$svnrepo"/$i || return 1
 	done
 '
 
diff --git a/t/t9146-git-svn-empty-dirs.sh b/t/t9146-git-svn-empty-dirs.sh
index 5f91c0d..80cb55f 100755
--- a/t/t9146-git-svn-empty-dirs.sh
+++ b/t/t9146-git-svn-empty-dirs.sh
@@ -8,7 +8,7 @@
 test_expect_success 'initialize repo' '
 	for i in a b c d d/e d/e/f "weird file name"
 	do
-		svn_cmd mkdir -m "mkdir $i" "$svnrepo"/"$i"
+		svn_cmd mkdir -m "mkdir $i" "$svnrepo"/"$i" || return 1
 	done
 '
 
@@ -102,7 +102,7 @@
 test_expect_success 'initialize trunk' '
 	for i in trunk trunk/a trunk/"weird file name"
 	do
-		svn_cmd mkdir -m "mkdir $i" "$svnrepo"/"$i"
+		svn_cmd mkdir -m "mkdir $i" "$svnrepo"/"$i" || return 1
 	done
 '
 
diff --git a/t/t9147-git-svn-include-paths.sh b/t/t9147-git-svn-include-paths.sh
index d292bf9..257fc8f 100755
--- a/t/t9147-git-svn-include-paths.sh
+++ b/t/t9147-git-svn-include-paths.sh
@@ -28,7 +28,7 @@
 test_expect_success 'clone an SVN repository with filter to include qqq directory' '
 	git svn clone --include-paths="qqq" "$svnrepo" g &&
 	echo test_qqq > expect &&
-	for i in g/*/*.txt; do cat $i >> expect2; done &&
+	for i in g/*/*.txt; do cat $i >> expect2 || return 1; done &&
 	test_cmp expect expect2
 '
 
@@ -38,7 +38,7 @@
 	( cd c && git svn fetch --include-paths="qqq" ) &&
 	rm expect2 &&
 	echo test_qqq > expect &&
-	for i in c/*/*.txt; do cat $i >> expect2; done &&
+	for i in c/*/*.txt; do cat $i >> expect2 || return 1; done &&
 	test_cmp expect expect2
 '
 
@@ -64,7 +64,7 @@
 		cd g &&
 		git svn rebase &&
 		printf "test_qqq\nb\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -75,7 +75,7 @@
 		cd c &&
 		git svn rebase --include-paths="qqq" &&
 		printf "test_qqq\nb\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -96,7 +96,7 @@
 		cd g &&
 		git svn rebase &&
 		printf "test_qqq\nb\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -107,7 +107,7 @@
 		cd c &&
 		git svn rebase --include-paths="qqq" &&
 		printf "test_qqq\nb\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -129,7 +129,7 @@
 		cd g &&
 		git svn rebase &&
 		printf "test_qqq\nb\nygg\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
@@ -140,7 +140,7 @@
 		cd c &&
 		git svn rebase --include-paths="qqq" &&
 		printf "test_qqq\nb\nygg\n" > expect &&
-		for i in */*.txt; do cat $i >> expect2; done &&
+		for i in */*.txt; do cat $i >> expect2 || exit 1; done &&
 		test_cmp expect2 expect &&
 		rm expect expect2
 	)
diff --git a/t/t9151-svn-mergeinfo.sh b/t/t9151-svn-mergeinfo.sh
index 1fbe84f..c93a5be 100755
--- a/t/t9151-svn-mergeinfo.sh
+++ b/t/t9151-svn-mergeinfo.sh
@@ -5,9 +5,6 @@
 
 test_description='git-svn svn mergeinfo properties'
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./lib-git-svn.sh
 
 test_expect_success 'load svn dump' "
diff --git a/t/t9152-svn-empty-dirs-after-gc.sh b/t/t9152-svn-empty-dirs-after-gc.sh
index 89f285d..a597c42 100755
--- a/t/t9152-svn-empty-dirs-after-gc.sh
+++ b/t/t9152-svn-empty-dirs-after-gc.sh
@@ -8,7 +8,7 @@
 test_expect_success 'initialize repo' '
 	for i in a b c d d/e d/e/f "weird file name"
 	do
-		svn_cmd mkdir -m "mkdir $i" "$svnrepo"/"$i"
+		svn_cmd mkdir -m "mkdir $i" "$svnrepo"/"$i" || return 1
 	done
 '
 
diff --git a/t/t9167-git-svn-cmd-branch-subproject.sh b/t/t9167-git-svn-cmd-branch-subproject.sh
index ba35fc0..d9fd111 100755
--- a/t/t9167-git-svn-cmd-branch-subproject.sh
+++ b/t/t9167-git-svn-cmd-branch-subproject.sh
@@ -4,6 +4,8 @@
 #
 
 test_description='git svn branch for subproject clones'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./lib-git-svn.sh
 
 test_expect_success 'initialize svnrepo' '
diff --git a/t/t9302-fast-import-unpack-limit.sh b/t/t9302-fast-import-unpack-limit.sh
index f519e4f..d8b1f94 100755
--- a/t/t9302-fast-import-unpack-limit.sh
+++ b/t/t9302-fast-import-unpack-limit.sh
@@ -1,5 +1,7 @@
 #!/bin/sh
 test_description='test git fast-import unpack limit'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'create loose objects on import' '
diff --git a/t/t9303-fast-import-compression.sh b/t/t9303-fast-import-compression.sh
index 57d9165..4f5bf40 100755
--- a/t/t9303-fast-import-compression.sh
+++ b/t/t9303-fast-import-compression.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='compression setting of fast-import utility'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 import_large () {
diff --git a/t/t9304-fast-import-marks.sh b/t/t9304-fast-import-marks.sh
index d4359db..bed01c9 100755
--- a/t/t9304-fast-import-marks.sh
+++ b/t/t9304-fast-import-marks.sh
@@ -16,7 +16,7 @@
 	blob=$(git rev-parse HEAD:one.t) &&
 	for i in $(test_seq 1024 16384)
 	do
-		echo ":$i $blob"
+		echo ":$i $blob" || return 1
 	done >>marks
 '
 
diff --git a/t/t9350-fast-export.sh b/t/t9350-fast-export.sh
index 409b48e..7b7a18d 100755
--- a/t/t9350-fast-export.sh
+++ b/t/t9350-fast-export.sh
@@ -750,4 +750,36 @@
 	)
 '
 
+
+test_expect_success 'fast-export --first-parent outputs all revisions output by revision walk' '
+	git init first-parent &&
+	(
+		cd first-parent &&
+		test_commit A &&
+		git checkout -b topic1 &&
+		test_commit B &&
+		git checkout main &&
+		git merge --no-ff topic1 &&
+
+		git checkout -b topic2 &&
+		test_commit C &&
+		git checkout main &&
+		git merge --no-ff topic2 &&
+
+		test_commit D &&
+
+		git fast-export main -- --first-parent >first-parent-export &&
+		git fast-export main -- --first-parent --reverse >first-parent-reverse-export &&
+		test_cmp first-parent-export first-parent-reverse-export &&
+
+		git init import &&
+		git -C import fast-import <first-parent-export &&
+
+		git log --format="%ad %s" --first-parent main >expected &&
+		git -C import log --format="%ad %s" --all >actual &&
+		test_cmp expected actual &&
+		test_line_count = 4 actual
+	)
+'
+
 test_done
diff --git a/t/t9400-git-cvsserver-server.sh b/t/t9400-git-cvsserver-server.sh
index 17f988e..210ddf0 100755
--- a/t/t9400-git-cvsserver-server.sh
+++ b/t/t9400-git-cvsserver-server.sh
@@ -338,7 +338,7 @@
   '(for dir in A A/B A/B/C A/D E; do
       mkdir $dir &&
       echo "test file in $dir" >"$dir/file_in_$(echo $dir|sed -e "s#/# #g")"  &&
-      git add $dir
+      git add $dir || exit 1
    done) &&
    git commit -q -m "deep sub directory structure" &&
    git push gitcvs.git >/dev/null &&
@@ -350,10 +350,9 @@
 	test_cmp "$dir/$filename" "../$dir/$filename"; then
         :
       else
-        echo >failure
+	exit 1
       fi
-    done) &&
-   test ! -f failure'
+    done)'
 
 cd "$WORKDIR"
 test_expect_success 'cvs update (delete file)' \
@@ -382,7 +381,7 @@
    for i in 1 2 3 4 5 6 7
    do
      echo Line $i >>merge &&
-     echo Line $i >>expected
+     echo Line $i >>expected || return 1
    done &&
    echo Line 8 >>expected &&
    git add merge &&
@@ -592,7 +591,7 @@
     cd cvswork &&
     GIT_CONFIG="$git_config" cvs annotate merge >../out &&
     sed -e "s/ .*//" ../out >../actual &&
-    for i in 3 1 1 1 1 1 1 1 2 4; do echo 1.$i; done >../expect &&
+    printf "1.%d\n" 3 1 1 1 1 1 1 1 2 4 >../expect &&
     test_cmp ../expect ../actual
 '
 
diff --git a/t/t9603-cvsimport-patchsets.sh b/t/t9603-cvsimport-patchsets.sh
index 0e9daa5..19f38f7 100755
--- a/t/t9603-cvsimport-patchsets.sh
+++ b/t/t9603-cvsimport-patchsets.sh
@@ -12,9 +12,6 @@
 # bug.
 
 test_description='git cvsimport testing for correct patchset estimation'
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./lib-cvs.sh
 
 setup_cvs_test_repository t9603
diff --git a/t/t9800-git-p4-basic.sh b/t/t9800-git-p4-basic.sh
index 81bc8e8..806005a 100755
--- a/t/t9800-git-p4-basic.sh
+++ b/t/t9800-git-p4-basic.sh
@@ -171,7 +171,7 @@
 			cd "$git" &&
 			git ls-files >lines &&
 			test_line_count = 8 lines
-		)
+		) || return 1
 	done
 '
 
diff --git a/t/t9810-git-p4-rcs.sh b/t/t9810-git-p4-rcs.sh
index e383688..5fe8331 100755
--- a/t/t9810-git-p4-rcs.sh
+++ b/t/t9810-git-p4-rcs.sh
@@ -4,6 +4,8 @@
 
 . ./lib-git-p4.sh
 
+CP1252="\223\224"
+
 test_expect_success 'start p4d' '
 	start_p4d
 '
@@ -32,6 +34,9 @@
 		p4 submit -d "filek" &&
 		p4 add -t text+ko fileko &&
 		p4 submit -d "fileko" &&
+		printf "$CP1252" >fileko_cp1252 &&
+		p4 add -t text+ko fileko_cp1252 &&
+		p4 submit -d "fileko_cp1252" &&
 		p4 add -t text file_text &&
 		p4 submit -d "file_text"
 	)
@@ -359,4 +364,14 @@
 	)
 '
 
+test_expect_success 'check cp1252 smart quote are preserved through RCS keyword processing' '
+	test_when_finished cleanup_git &&
+	git p4 clone --dest="$git" //depot &&
+	(
+		cd "$git" &&
+		printf "$CP1252" >expect &&
+		test_cmp_bin expect fileko_cp1252
+	)
+'
+
 test_done
diff --git a/t/t9818-git-p4-block.sh b/t/t9818-git-p4-block.sh
index 0db7ab9..de591d8 100755
--- a/t/t9818-git-p4-block.sh
+++ b/t/t9818-git-p4-block.sh
@@ -92,11 +92,11 @@
 	for i in $(test_seq 0 10)
 	do
 		p4_add_file "included/x$i" &&
-		p4_add_file "excluded/x$i"
+		p4_add_file "excluded/x$i" || return 1
 	done &&
 	for i in $(test_seq 0 10)
 	do
-		p4_add_file "excluded/y$i"
+		p4_add_file "excluded/y$i" || return 1
 	done
 '
 
@@ -123,7 +123,7 @@
 	do
 		for i in $(test_seq 1 10)
 		do
-			p4_add_file "$p/file$p$i"
+			p4_add_file "$p/file$p$i" || return 1
 		done
 	done
 '
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 5decc3b..98c6280 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -5,9 +5,6 @@
 
 test_description='test bash completion'
 
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
 . ./lib-bash.sh
 
 complete ()
@@ -879,7 +876,7 @@
 		refs/remotes/remote/branch-in-remote
 	do
 		git update-ref $remote_ref main &&
-		test_when_finished "git update-ref -d $remote_ref"
+		test_when_finished "git update-ref -d $remote_ref" || return 1
 	done &&
 	(
 		cur= &&
@@ -1052,7 +1049,7 @@
 		refs/remotes/remote/branch-in-remote
 	do
 		git update-ref $remote_ref main &&
-		test_when_finished "git update-ref -d $remote_ref"
+		test_when_finished "git update-ref -d $remote_ref" || return 1
 	done &&
 	(
 		cur=mat &&
@@ -2148,6 +2145,9 @@
 	--cover-from-description=Z
 	--cover-letter Z
 	EOF
+	test_completion "git send-email --val" <<-\EOF &&
+	--validate Z
+	EOF
 	test_completion "git send-email ma" "main "
 '
 
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index eef2262..c3d38aa 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -680,6 +680,17 @@
 			# Keep a list of missing prerequisites; restore
 			# the negative marker if necessary.
 			prerequisite=${negative_prereq:+!}$prerequisite
+
+			# Abort if this prereq was marked as required
+			if test -n "$GIT_TEST_REQUIRE_PREREQ"
+			then
+				case " $GIT_TEST_REQUIRE_PREREQ " in
+				*" $prerequisite "*)
+					BAIL_OUT "required prereq $prerequisite failed"
+					;;
+				esac
+			fi
+
 			if test -z "$missing_prereq"
 			then
 				missing_prereq=$prerequisite
@@ -1749,6 +1760,40 @@
 }
 
 # Check that the given command was invoked as part of the
+# trace2-format trace on stdin, but without an exact set of
+# arguments.
+#
+#	test_subcommand [!] <command> <args>... < <trace>
+#
+# For example, to look for an invocation of "git pack-objects"
+# with the "--honor-pack-keep" argument, use
+#
+#	GIT_TRACE2_EVENT=event.log git repack ... &&
+#	test_subcommand git pack-objects --honor-pack-keep <event.log
+#
+# If the first parameter passed is !, this instead checks that
+# the given command was not called.
+#
+test_subcommand_inexact () {
+	local negate=
+	if test "$1" = "!"
+	then
+		negate=t
+		shift
+	fi
+
+	local expr=$(printf '"%s".*' "$@")
+	expr="${expr%,}"
+
+	if test -n "$negate"
+	then
+		! grep "\"event\":\"child_start\".*\[$expr\]"
+	else
+		grep "\"event\":\"child_start\".*\[$expr\]"
+	fi
+}
+
+# Check that the given command was invoked as part of the
 # trace2-format trace on stdin.
 #
 #	test_region [!] <category> <label> git <command> <args>...
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 2679a75..0f7a137 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -476,6 +476,13 @@
 GIT_TRACE_BARE=1
 export GIT_TRACE_BARE
 
+# Some tests scan the GIT_TRACE2_EVENT feed for events, but the
+# default depth is 2, which frequently causes issues when the
+# events are wrapped in new regions. Set it to a sufficiently
+# large depth to avoid custom changes in the test suite.
+GIT_TRACE2_EVENT_NESTING=100
+export GIT_TRACE2_EVENT_NESTING
+
 # Use specific version of the index file format
 if test -n "${GIT_TEST_INDEX_VERSION:+isset}"
 then
@@ -489,6 +496,13 @@
 	export GIT_PERL_FATAL_WARNINGS
 fi
 
+case $GIT_TEST_FSYNC in
+'')
+	GIT_TEST_FSYNC=0
+	export GIT_TEST_FSYNC
+	;;
+esac
+
 # Add libc MALLOC and MALLOC_PERTURB test
 # only if we are not executing the test with valgrind
 if test -n "$valgrind" ||
@@ -589,6 +603,15 @@
 TERM=dumb
 export TERM USER_TERM
 
+# What is written by tests to stdout and stderr is sent to different places
+# depending on the test mode (e.g. /dev/null in non-verbose mode, piped to tee
+# with --tee option, etc.). We save the original stdin to FD #6 and stdout and
+# stderr to #5 and #7, so that the test framework can use them (e.g. for
+# printing errors within the test framework) independently of the test mode.
+exec 5>&1
+exec 6<&0
+exec 7>&2
+
 _error_exit () {
 	finalize_junit_xml
 	GIT_EXIT_OK=t
@@ -612,7 +635,7 @@
 	local bail_out="Bail out! "
 	local message="$1"
 
-	say_color error $bail_out "$message"
+	say_color >&5 error $bail_out "$message"
 	_error_exit
 }
 
@@ -637,9 +660,6 @@
 	exit 0
 fi
 
-exec 5>&1
-exec 6<&0
-exec 7>&2
 if test "$verbose_log" = "t"
 then
 	exec 3>>"$GIT_TEST_TEE_OUTPUT_FILE" 4>&3
@@ -669,6 +689,8 @@
 test_broken=0
 test_success=0
 
+test_missing_prereq=
+
 test_external_has_tap=0
 
 die () {
@@ -1069,6 +1091,14 @@
 			of_prereq=" of $test_prereq"
 		fi
 		skipped_reason="missing $missing_prereq${of_prereq}"
+
+		# Keep a list of all the missing prereq for result aggregation
+		if test -z "$missing_prereq"
+		then
+			test_missing_prereq=$missing_prereq
+		else
+			test_missing_prereq="$test_missing_prereq,$missing_prereq"
+		fi
 	fi
 
 	case "$to_skip" in
@@ -1175,6 +1205,7 @@
 		fixed $test_fixed
 		broken $test_broken
 		failed $test_failure
+		missing_prereq $test_missing_prereq
 
 		EOF
 	fi
@@ -1734,6 +1765,10 @@
 	sed -ne "s/^$1: //p"
 }
 
+test_lazy_prereq SIZE_T_IS_64BIT '
+	test 8 -eq "$(build_option sizeof-size_t)"
+'
+
 test_lazy_prereq LONG_IS_64BIT '
 	test 8 -le "$(build_option sizeof-long)"
 '
diff --git a/tag.c b/tag.c
index 3e18a41..dfbcd7f 100644
--- a/tag.c
+++ b/tag.c
@@ -25,8 +25,9 @@
 		return error("no signature found");
 	}
 
-	ret = check_signature(payload.buf, payload.len, signature.buf,
-				signature.len, &sigc);
+	sigc.payload_type = SIGNATURE_PAYLOAD_TAG;
+	sigc.payload = strbuf_detach(&payload, &sigc.payload_len);
+	ret = check_signature(&sigc, signature.buf, signature.len);
 
 	if (!(flags & GPG_VERIFY_OMIT_STATUS))
 		print_signature_buffer(&sigc, flags);
diff --git a/tmp-objdir.c b/tmp-objdir.c
index b8d880e..3d38eea 100644
--- a/tmp-objdir.c
+++ b/tmp-objdir.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "tmp-objdir.h"
+#include "chdir-notify.h"
 #include "dir.h"
 #include "sigchain.h"
 #include "string-list.h"
@@ -11,6 +12,8 @@
 struct tmp_objdir {
 	struct strbuf path;
 	struct strvec env;
+	struct object_directory *prev_odb;
+	int will_destroy;
 };
 
 /*
@@ -38,6 +41,9 @@
 	if (t == the_tmp_objdir)
 		the_tmp_objdir = NULL;
 
+	if (!on_signal && t->prev_odb)
+		restore_primary_odb(t->prev_odb, t->path.buf);
+
 	/*
 	 * This may use malloc via strbuf_grow(), but we should
 	 * have pre-grown t->path sufficiently so that this
@@ -52,6 +58,7 @@
 	 */
 	if (!on_signal)
 		tmp_objdir_free(t);
+
 	return err;
 }
 
@@ -121,7 +128,7 @@
 	return ret;
 }
 
-struct tmp_objdir *tmp_objdir_create(void)
+struct tmp_objdir *tmp_objdir_create(const char *prefix)
 {
 	static int installed_handlers;
 	struct tmp_objdir *t;
@@ -129,11 +136,16 @@
 	if (the_tmp_objdir)
 		BUG("only one tmp_objdir can be used at a time");
 
-	t = xmalloc(sizeof(*t));
+	t = xcalloc(1, sizeof(*t));
 	strbuf_init(&t->path, 0);
 	strvec_init(&t->env);
 
-	strbuf_addf(&t->path, "%s/incoming-XXXXXX", get_object_directory());
+	/*
+	 * Use a string starting with tmp_ so that the builtin/prune.c code
+	 * can recognize any stale objdirs left behind by a crash and delete
+	 * them.
+	 */
+	strbuf_addf(&t->path, "%s/tmp_objdir-%s-XXXXXX", get_object_directory(), prefix);
 
 	/*
 	 * Grow the strbuf beyond any filename we expect to be placed in it.
@@ -269,6 +281,13 @@
 	if (!t)
 		return 0;
 
+	if (t->prev_odb) {
+		if (the_repository->objects->odb->will_destroy)
+			BUG("migrating an ODB that was marked for destruction");
+		restore_primary_odb(t->prev_odb, t->path.buf);
+		t->prev_odb = NULL;
+	}
+
 	strbuf_addbuf(&src, &t->path);
 	strbuf_addstr(&dst, get_object_directory());
 
@@ -292,3 +311,33 @@
 {
 	add_to_alternates_memory(t->path.buf);
 }
+
+void tmp_objdir_replace_primary_odb(struct tmp_objdir *t, int will_destroy)
+{
+	if (t->prev_odb)
+		BUG("the primary object database is already replaced");
+	t->prev_odb = set_temporary_primary_odb(t->path.buf, will_destroy);
+	t->will_destroy = will_destroy;
+}
+
+struct tmp_objdir *tmp_objdir_unapply_primary_odb(void)
+{
+	if (!the_tmp_objdir || !the_tmp_objdir->prev_odb)
+		return NULL;
+
+	restore_primary_odb(the_tmp_objdir->prev_odb, the_tmp_objdir->path.buf);
+	the_tmp_objdir->prev_odb = NULL;
+	return the_tmp_objdir;
+}
+
+void tmp_objdir_reapply_primary_odb(struct tmp_objdir *t, const char *old_cwd,
+		const char *new_cwd)
+{
+	char *path;
+
+	path = reparent_relative_path(old_cwd, new_cwd, t->path.buf);
+	strbuf_reset(&t->path);
+	strbuf_addstr(&t->path, path);
+	free(path);
+	tmp_objdir_replace_primary_odb(t, t->will_destroy);
+}
diff --git a/tmp-objdir.h b/tmp-objdir.h
index b1e45b4..cda5ec7 100644
--- a/tmp-objdir.h
+++ b/tmp-objdir.h
@@ -10,7 +10,7 @@
  *
  * Example:
  *
- *	struct tmp_objdir *t = tmp_objdir_create();
+ *	struct tmp_objdir *t = tmp_objdir_create("incoming");
  *	if (!run_command_v_opt_cd_env(cmd, 0, NULL, tmp_objdir_env(t)) &&
  *	    !tmp_objdir_migrate(t))
  *		printf("success!\n");
@@ -22,9 +22,10 @@
 struct tmp_objdir;
 
 /*
- * Create a new temporary object directory; returns NULL on failure.
+ * Create a new temporary object directory with the specified prefix;
+ * returns NULL on failure.
  */
-struct tmp_objdir *tmp_objdir_create(void);
+struct tmp_objdir *tmp_objdir_create(const char *prefix);
 
 /*
  * Return a list of environment strings, suitable for use with
@@ -51,4 +52,26 @@
  */
 void tmp_objdir_add_as_alternate(const struct tmp_objdir *);
 
+/*
+ * Replaces the writable object store in the current process with the temporary
+ * object directory and makes the former main object store an alternate.
+ * If will_destroy is nonzero, the object directory may not be migrated.
+ */
+void tmp_objdir_replace_primary_odb(struct tmp_objdir *, int will_destroy);
+
+/*
+ * If the primary object database was replaced by a temporary object directory,
+ * restore it to its original value while keeping the directory contents around.
+ * Returns NULL if the primary object database was not replaced.
+ */
+struct tmp_objdir *tmp_objdir_unapply_primary_odb(void);
+
+/*
+ * Reapplies the former primary temporary object database, after potentially
+ * changing its relative path.
+ */
+void tmp_objdir_reapply_primary_odb(struct tmp_objdir *, const char *old_cwd,
+		const char *new_cwd);
+
+
 #endif /* TMP_OBJDIR_H */
diff --git a/trace2/tr2_dst.c b/trace2/tr2_dst.c
index bda283e..8a21dd2 100644
--- a/trace2/tr2_dst.c
+++ b/trace2/tr2_dst.c
@@ -1,4 +1,5 @@
 #include "cache.h"
+#include "sigchain.h"
 #include "trace2/tr2_dst.h"
 #include "trace2/tr2_sid.h"
 #include "trace2/tr2_sysenv.h"
@@ -360,6 +361,7 @@
 void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line)
 {
 	int fd = tr2_dst_get_trace_fd(dst);
+	ssize_t bytes;
 
 	strbuf_complete_line(buf_line); /* ensure final NL on buffer */
 
@@ -378,12 +380,15 @@
 	 *
 	 * If we get an IO error, just close the trace dst.
 	 */
-	if (write(fd, buf_line->buf, buf_line->len) >= 0)
+	sigchain_push(SIGPIPE, SIG_IGN);
+	bytes = write(fd, buf_line->buf, buf_line->len);
+	sigchain_pop(SIGPIPE);
+	if (bytes >= 0)
 		return;
 
+	tr2_dst_trace_disable(dst);
 	if (tr2_dst_want_warning())
 		warning("unable to write trace to '%s': %s",
 			tr2_sysenv_display_name(dst->sysenv_var),
 			strerror(errno));
-	tr2_dst_trace_disable(dst);
 }
diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
index 3a00144..bd17ecd 100644
--- a/trace2/tr2_tgt_event.c
+++ b/trace2/tr2_tgt_event.c
@@ -354,7 +354,7 @@
 	jw_object_inline_begin_array(&jw, "argv");
 	if (cmd->git_cmd)
 		jw_array_string(&jw, "git");
-	jw_array_argv(&jw, cmd->argv);
+	jw_array_argv(&jw, cmd->args.v);
 	jw_end(&jw);
 	jw_end(&jw);
 
diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
index 58d9e43..6e429a3 100644
--- a/trace2/tr2_tgt_normal.c
+++ b/trace2/tr2_tgt_normal.c
@@ -232,7 +232,7 @@
 	strbuf_addch(&buf_payload, ' ');
 	if (cmd->git_cmd)
 		strbuf_addstr(&buf_payload, "git ");
-	sq_append_quote_argv_pretty(&buf_payload, cmd->argv);
+	sq_append_quote_argv_pretty(&buf_payload, cmd->args.v);
 
 	normal_io_write_fl(file, line, &buf_payload);
 	strbuf_release(&buf_payload);
diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
index e4acca1..2ff9cf7 100644
--- a/trace2/tr2_tgt_perf.c
+++ b/trace2/tr2_tgt_perf.c
@@ -335,10 +335,10 @@
 	strbuf_addstr(&buf_payload, " argv:[");
 	if (cmd->git_cmd) {
 		strbuf_addstr(&buf_payload, "git");
-		if (cmd->argv[0])
+		if (cmd->args.nr)
 			strbuf_addch(&buf_payload, ' ');
 	}
-	sq_append_quote_argv_pretty(&buf_payload, cmd->argv);
+	sq_append_quote_argv_pretty(&buf_payload, cmd->args.v);
 	strbuf_addch(&buf_payload, ']');
 
 	perf_io_write_fl(file, line, event_name, NULL, &us_elapsed_absolute,
diff --git a/trailer.c b/trailer.c
index 7c7cb61..1b12f77 100644
--- a/trailer.c
+++ b/trailer.c
@@ -236,7 +236,7 @@
 			strbuf_replace(&cmd, TRAILER_ARG_STRING, arg);
 		strvec_push(&cp.args, cmd.buf);
 	}
-	cp.env = local_repo_env;
+	strvec_pushv(&cp.env_array, (const char **)local_repo_env);
 	cp.no_stdin = 1;
 	cp.use_shell = 1;
 
diff --git a/transport.c b/transport.c
index e4f1dec..2a3e324 100644
--- a/transport.c
+++ b/transport.c
@@ -1204,16 +1204,15 @@
 	struct ref *r;
 	struct child_process proc = CHILD_PROCESS_INIT;
 	struct strbuf buf;
-	const char *argv[4];
+	const char *hook_path = find_hook("pre-push");
 
-	if (!(argv[0] = find_hook("pre-push")))
+	if (!hook_path)
 		return 0;
 
-	argv[1] = transport->remote->name;
-	argv[2] = transport->url;
-	argv[3] = NULL;
+	strvec_push(&proc.args, hook_path);
+	strvec_push(&proc.args, transport->remote->name);
+	strvec_push(&proc.args, transport->url);
 
-	proc.argv = argv;
 	proc.in = -1;
 	proc.trace2_hook_name = "pre-push";
 
@@ -1457,13 +1456,18 @@
 	return rc;
 }
 
-void transport_unlock_pack(struct transport *transport)
+void transport_unlock_pack(struct transport *transport, unsigned int flags)
 {
+	int in_signal_handler = !!(flags & TRANSPORT_UNLOCK_PACK_IN_SIGNAL_HANDLER);
 	int i;
 
 	for (i = 0; i < transport->pack_lockfiles.nr; i++)
-		unlink_or_warn(transport->pack_lockfiles.items[i].string);
-	string_list_clear(&transport->pack_lockfiles, 0);
+		if (in_signal_handler)
+			unlink(transport->pack_lockfiles.items[i].string);
+		else
+			unlink_or_warn(transport->pack_lockfiles.items[i].string);
+	if (!in_signal_handler)
+		string_list_clear(&transport->pack_lockfiles, 0);
 }
 
 int transport_connect(struct transport *transport, const char *name,
diff --git a/transport.h b/transport.h
index 8bb4c8b..3f16e50 100644
--- a/transport.h
+++ b/transport.h
@@ -279,7 +279,19 @@
  */
 const struct git_hash_algo *transport_get_hash_algo(struct transport *transport);
 int transport_fetch_refs(struct transport *transport, struct ref *refs);
-void transport_unlock_pack(struct transport *transport);
+
+/*
+ * If this flag is set, unlocking will avoid to call non-async-signal-safe
+ * functions. This will necessarily leave behind some data structures which
+ * cannot be cleaned up.
+ */
+#define TRANSPORT_UNLOCK_PACK_IN_SIGNAL_HANDLER (1 << 0)
+
+/*
+ * Unlock all packfiles locked by the transport.
+ */
+void transport_unlock_pack(struct transport *transport, unsigned int flags);
+
 int transport_disconnect(struct transport *transport);
 char *transport_anonymize_url(const char *url);
 void transport_take_over(struct transport *transport,
diff --git a/tree-diff.c b/tree-diff.c
index 437c98a..69031d7 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -603,8 +603,7 @@
 	 * about dry-run mode and returns wildcard info.
 	 */
 	if (opt->pathspec.has_wildcard)
-		die("BUG:%s:%d: wildcards are not supported",
-		    __FILE__, __LINE__);
+		BUG("wildcards are not supported");
 #endif
 
 	/* Remove the file creation entry from the diff queue, and remember it */
diff --git a/unpack-trees.c b/unpack-trees.c
index 89ca95c..360844b 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -36,6 +36,9 @@
 	/* ERROR_NOT_UPTODATE_DIR */
 	"Updating '%s' would lose untracked files in it",
 
+	/* ERROR_CWD_IN_THE_WAY */
+	"Refusing to remove '%s' since it is the current working directory.",
+
 	/* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
 	"Untracked working tree file '%s' would be overwritten by merge.",
 
@@ -131,6 +134,9 @@
 	msgs[ERROR_NOT_UPTODATE_DIR] =
 		_("Updating the following directories would lose untracked files in them:\n%s");
 
+	msgs[ERROR_CWD_IN_THE_WAY] =
+		_("Refusing to remove the current working directory:\n%s");
+
 	if (!strcmp(cmd, "checkout"))
 		msg = advice_enabled(ADVICE_COMMIT_BEFORE_MERGE)
 		      ? _("The following untracked working tree files would be removed by checkout:\n%%s"
@@ -645,17 +651,24 @@
 	}
 }
 
-static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
+static struct cache_entry *next_cache_entry(struct unpack_trees_options *o, int *hint)
 {
 	const struct index_state *index = o->src_index;
 	int pos = o->cache_bottom;
 
+	if (*hint > pos)
+		pos = *hint;
+
 	while (pos < index->cache_nr) {
 		struct cache_entry *ce = index->cache[pos];
-		if (!(ce->ce_flags & CE_UNPACKED))
+		if (!(ce->ce_flags & CE_UNPACKED)) {
+			*hint = pos + 1;
 			return ce;
+		}
 		pos++;
 	}
+
+	*hint = pos;
 	return NULL;
 }
 
@@ -1231,7 +1244,9 @@
 
 /*
  * Given a sparse directory entry 'ce', compare ce->name to
- * info->name + '/' + p->path + '/' if info->name is non-empty.
+ * info->traverse_path + p->path + '/' if info->traverse_path
+ * is non-empty.
+ *
  * Compare ce->name to p->path + '/' otherwise. Note that
  * ce->name must end in a trailing '/' because it is a sparse
  * directory entry.
@@ -1243,11 +1258,11 @@
 	assert(S_ISSPARSEDIR(ce->ce_mode));
 	assert(ce->name[ce->ce_namelen - 1] == '/');
 
-	if (info->namelen)
-		return ce->ce_namelen == info->namelen + p->pathlen + 2 &&
-		       ce->name[info->namelen] == '/' &&
-		       !strncmp(ce->name, info->name, info->namelen) &&
-		       !strncmp(ce->name + info->namelen + 1, p->path, p->pathlen);
+	if (info->pathlen)
+		return ce->ce_namelen == info->pathlen + p->pathlen + 1 &&
+		       ce->name[info->pathlen - 1] == '/' &&
+		       !strncmp(ce->name, info->traverse_path, info->pathlen) &&
+		       !strncmp(ce->name + info->pathlen, p->path, p->pathlen);
 	return ce->ce_namelen == p->pathlen + 1 &&
 	       !strncmp(ce->name, p->path, p->pathlen);
 }
@@ -1365,12 +1380,13 @@
 
 	/* Are we supposed to look at the index too? */
 	if (o->merge) {
+		int hint = -1;
 		while (1) {
 			int cmp;
 			struct cache_entry *ce;
 
 			if (o->diff_index_cached)
-				ce = next_cache_entry(o);
+				ce = next_cache_entry(o, &hint);
 			else
 				ce = find_cache_entry(info, p);
 
@@ -1690,7 +1706,7 @@
 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
 {
 	struct repository *repo = the_repository;
-	int i, ret;
+	int i, hint, ret;
 	static struct cache_entry *dfc;
 	struct pattern_list pl;
 	int free_pattern_list = 0;
@@ -1779,13 +1795,15 @@
 		info.pathspec = o->pathspec;
 
 		if (o->prefix) {
+			hint = -1;
+
 			/*
 			 * Unpack existing index entries that sort before the
 			 * prefix the tree is spliced into.  Note that o->merge
 			 * is always true in this case.
 			 */
 			while (1) {
-				struct cache_entry *ce = next_cache_entry(o);
+				struct cache_entry *ce = next_cache_entry(o, &hint);
 				if (!ce)
 					break;
 				if (ce_in_traverse_path(ce, &info))
@@ -1806,8 +1824,9 @@
 
 	/* Any left-over entries in the index? */
 	if (o->merge) {
+		hint = -1;
 		while (1) {
-			struct cache_entry *ce = next_cache_entry(o);
+			struct cache_entry *ce = next_cache_entry(o, &hint);
 			if (!ce)
 				break;
 			if (unpack_index_entry(ce, o) < 0)
@@ -2146,10 +2165,7 @@
 		cnt++;
 	}
 
-	/*
-	 * Then we need to make sure that we do not lose a locally
-	 * present file that is not ignored.
-	 */
+	/* Do not lose a locally present file that is not ignored. */
 	pathbuf = xstrfmt("%.*s/", namelen, ce->name);
 
 	memset(&d, 0, sizeof(d));
@@ -2160,6 +2176,12 @@
 	free(pathbuf);
 	if (i)
 		return add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
+
+	/* Do not lose startup_info->original_cwd */
+	if (startup_info->original_cwd &&
+	    !strcmp(startup_info->original_cwd, ce->name))
+		return add_rejected_path(o, ERROR_CWD_IN_THE_WAY, ce->name);
+
 	return cnt;
 }
 
@@ -2252,10 +2274,19 @@
 	int len;
 	struct stat st;
 
-	if (o->index_only || !o->update ||
-	    o->reset == UNPACK_RESET_OVERWRITE_UNTRACKED)
+	if (o->index_only || !o->update)
 		return 0;
 
+	if (o->reset == UNPACK_RESET_OVERWRITE_UNTRACKED) {
+		/* Avoid nuking startup_info->original_cwd... */
+		if (startup_info->original_cwd &&
+		    !strcmp(startup_info->original_cwd, ce->name))
+			return add_rejected_path(o, ERROR_CWD_IN_THE_WAY,
+						 ce->name);
+		/* ...but nuke anything else. */
+		return 0;
+	}
+
 	len = check_leading_path(ce->name, ce_namelen(ce), 0);
 	if (!len)
 		return 0;
diff --git a/unpack-trees.h b/unpack-trees.h
index 71ffb7e..efb9edf 100644
--- a/unpack-trees.h
+++ b/unpack-trees.h
@@ -19,6 +19,7 @@
 	ERROR_WOULD_OVERWRITE = 0,
 	ERROR_NOT_UPTODATE_FILE,
 	ERROR_NOT_UPTODATE_DIR,
+	ERROR_CWD_IN_THE_WAY,
 	ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN,
 	ERROR_WOULD_LOSE_UNTRACKED_REMOVED,
 	ERROR_BIND_OVERLAP,
diff --git a/upload-pack.c b/upload-pack.c
index c78d55b..8acc987 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -194,7 +194,13 @@
 }
 
 struct output_state {
-	char buffer[8193];
+	/*
+	 * We do writes no bigger than LARGE_PACKET_DATA_MAX - 1, because with
+	 * sideband-64k the band designator takes up 1 byte of space. Because
+	 * relay_pack_data keeps the last byte to itself, we make the buffer 1
+	 * byte bigger than the intended maximum write size.
+	 */
+	char buffer[(LARGE_PACKET_DATA_MAX - 1) + 1];
 	int used;
 	unsigned packfile_uris_started : 1;
 	unsigned packfile_started : 1;
@@ -269,7 +275,7 @@
 			     const struct string_list *uri_protocols)
 {
 	struct child_process pack_objects = CHILD_PROCESS_INIT;
-	struct output_state output_state = { { 0 } };
+	struct output_state *output_state = xcalloc(1, sizeof(struct output_state));
 	char progress[128];
 	char abort_msg[] = "aborting due to possible repository "
 		"corruption on the remote side.";
@@ -404,7 +410,7 @@
 		}
 		if (0 <= pu && (pfd[pu].revents & (POLLIN|POLLHUP))) {
 			int result = relay_pack_data(pack_objects.out,
-						     &output_state,
+						     output_state,
 						     pack_data->use_sideband,
 						     !!uri_protocols);
 
@@ -438,11 +444,12 @@
 	}
 
 	/* flush the data */
-	if (output_state.used > 0) {
-		send_client_data(1, output_state.buffer, output_state.used,
+	if (output_state->used > 0) {
+		send_client_data(1, output_state->buffer, output_state->used,
 				 pack_data->use_sideband);
 		fprintf(stderr, "flushed.\n");
 	}
+	free(output_state);
 	if (pack_data->use_sideband)
 		packet_flush(1);
 	return;
@@ -596,14 +603,11 @@
 				struct object_array *reachable,
 				enum allow_uor allow_uor)
 {
-	static const char *argv[] = {
-		"rev-list", "--stdin", NULL,
-	};
 	struct object *o;
 	FILE *cmd_in = NULL;
 	int i;
 
-	cmd->argv = argv;
+	strvec_pushl(&cmd->args, "rev-list", "--stdin", NULL);
 	cmd->git_cmd = 1;
 	cmd->no_stderr = 1;
 	cmd->in = -1;
diff --git a/urlmatch.c b/urlmatch.c
index 33a2ccd..03ad3f3 100644
--- a/urlmatch.c
+++ b/urlmatch.c
@@ -5,7 +5,7 @@
 #define URL_DIGIT "0123456789"
 #define URL_ALPHADIGIT URL_ALPHA URL_DIGIT
 #define URL_SCHEME_CHARS URL_ALPHADIGIT "+.-"
-#define URL_HOST_CHARS URL_ALPHADIGIT ".-[:]" /* IPv6 literals need [:] */
+#define URL_HOST_CHARS URL_ALPHADIGIT ".-_[:]" /* IPv6 literals need [:] */
 #define URL_UNSAFE_CHARS " <>\"%{}|\\^`" /* plus 0x00-0x1F,0x7F-0xFF */
 #define URL_GEN_RESERVED ":/?#[]@"
 #define URL_SUB_RESERVED "!$&'()*+,;="
diff --git a/usage.c b/usage.c
index c7d233b..9943dd8 100644
--- a/usage.c
+++ b/usage.c
@@ -6,7 +6,7 @@
 #include "git-compat-util.h"
 #include "cache.h"
 
-void vreportf(const char *prefix, const char *err, va_list params)
+static void vreportf(const char *prefix, const char *err, va_list params)
 {
 	char msg[4096];
 	char *p, *pend = msg + sizeof(msg);
@@ -55,6 +55,12 @@
 	exit(129);
 }
 
+static void die_message_builtin(const char *err, va_list params)
+{
+	trace2_cmd_error_va(err, params);
+	vreportf("fatal: ", err, params);
+}
+
 /*
  * We call trace2_cmd_error_va() in the below functions first and
  * expect it to va_copy 'params' before using it (because an 'ap' can
@@ -62,10 +68,9 @@
  */
 static NORETURN void die_builtin(const char *err, va_list params)
 {
-	trace2_cmd_error_va(err, params);
+	report_fn die_message_fn = get_die_message_routine();
 
-	vreportf("fatal: ", err, params);
-
+	die_message_fn(err, params);
 	exit(128);
 }
 
@@ -109,6 +114,7 @@
  * (ugh), so keep things static. */
 static NORETURN_PTR report_fn usage_routine = usage_builtin;
 static NORETURN_PTR report_fn die_routine = die_builtin;
+static report_fn die_message_routine = die_message_builtin;
 static report_fn error_routine = error_builtin;
 static report_fn warn_routine = warn_builtin;
 static int (*die_is_recursing)(void) = die_is_recursing_builtin;
@@ -118,6 +124,11 @@
 	die_routine = routine;
 }
 
+report_fn get_die_message_routine(void)
+{
+	return die_message_routine;
+}
+
 void set_error_routine(report_fn routine)
 {
 	error_routine = routine;
@@ -211,6 +222,29 @@
 	va_end(params);
 }
 
+#undef die_message
+int die_message(const char *err, ...)
+{
+	va_list params;
+
+	va_start(params, err);
+	die_message_routine(err, params);
+	va_end(params);
+	return 128;
+}
+
+#undef die_message_errno
+int die_message_errno(const char *fmt, ...)
+{
+	char buf[1024];
+	va_list params;
+
+	va_start(params, fmt);
+	die_message_routine(fmt_with_err(buf, sizeof(buf), fmt), params);
+	va_end(params);
+	return 128;
+}
+
 #undef error_errno
 int error_errno(const char *fmt, ...)
 {
diff --git a/worktree.c b/worktree.c
index 092a4f9..6f598dc 100644
--- a/worktree.c
+++ b/worktree.c
@@ -28,11 +28,13 @@
 {
 	int flags;
 	const char *target;
+	int ignore_errno;
 
 	target = refs_resolve_ref_unsafe(get_worktree_ref_store(wt),
 					 "HEAD",
 					 0,
-					 &wt->head_oid, &flags);
+					 &wt->head_oid, &flags,
+					 &ignore_errno);
 	if (!target)
 		return;
 
@@ -402,22 +404,19 @@
  * bisect). New commands that do similar things should update this
  * function as well.
  */
-const struct worktree *find_shared_symref(const char *symref,
+const struct worktree *find_shared_symref(struct worktree **worktrees,
+					  const char *symref,
 					  const char *target)
 {
 	const struct worktree *existing = NULL;
-	static struct worktree **worktrees;
 	int i = 0;
 
-	if (worktrees)
-		free_worktrees(worktrees);
-	worktrees = get_worktrees();
-
 	for (i = 0; worktrees[i]; i++) {
 		struct worktree *wt = worktrees[i];
 		const char *symref_target;
 		struct ref_store *refs;
 		int flags;
+		int ignore_errno;
 
 		if (wt->is_bare)
 			continue;
@@ -435,7 +434,8 @@
 
 		refs = get_worktree_ref_store(wt);
 		symref_target = refs_resolve_ref_unsafe(refs, symref, 0,
-							NULL, &flags);
+							NULL, &flags,
+							&ignore_errno);
 		if ((flags & REF_ISSYMREF) &&
 		    symref_target && !strcmp(symref_target, target)) {
 			existing = wt;
@@ -563,16 +563,17 @@
 		struct worktree *wt = *p;
 		struct object_id oid;
 		int flag;
+		int ignore_errno;
 
 		if (wt->is_current)
 			continue;
 
 		strbuf_reset(&refname);
 		strbuf_worktree_ref(wt, &refname, "HEAD");
-		if (!refs_read_ref_full(get_main_ref_store(the_repository),
-					refname.buf,
-					RESOLVE_REF_READING,
-					&oid, &flag))
+		if (refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
+					    refname.buf,
+					    RESOLVE_REF_READING,
+					    &oid, &flag, &ignore_errno))
 			ret = fn(refname.buf, &oid, flag, cb_data);
 		if (ret)
 			break;
diff --git a/worktree.h b/worktree.h
index 8b7c408..9e06fcb 100644
--- a/worktree.h
+++ b/worktree.h
@@ -143,9 +143,10 @@
 /*
  * Check if a per-worktree symref points to a ref in the main worktree
  * or any linked worktree, and return the worktree that holds the ref,
- * or NULL otherwise. The result may be destroyed by the next call.
+ * or NULL otherwise.
  */
-const struct worktree *find_shared_symref(const char *symref,
+const struct worktree *find_shared_symref(struct worktree **worktrees,
+					  const char *symref,
 					  const char *target);
 
 /*
diff --git a/write-or-die.c b/write-or-die.c
index 0b1ec81..a3d5784 100644
--- a/write-or-die.c
+++ b/write-or-die.c
@@ -1,4 +1,5 @@
 #include "cache.h"
+#include "config.h"
 #include "run-command.h"
 
 /*
@@ -57,6 +58,10 @@
 
 void fsync_or_die(int fd, const char *msg)
 {
+	if (use_fsync < 0)
+		use_fsync = git_env_bool("GIT_TEST_FSYNC", 1);
+	if (!use_fsync)
+		return;
 	while (fsync(fd) < 0) {
 		if (errno != EINTR)
 			die_errno("fsync error on '%s'", msg);
diff --git a/wt-status.c b/wt-status.c
index e4f29b2..335e723 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -948,11 +948,17 @@
 	return 0;
 }
 
+static int count_stash_entries(void)
+{
+	int n = 0;
+	for_each_reflog_ent("refs/stash", stash_count_refs, &n);
+	return n;
+}
+
 static void wt_longstatus_print_stash_summary(struct wt_status *s)
 {
-	int stash_count = 0;
+	int stash_count = count_stash_entries();
 
-	for_each_reflog_ent("refs/stash", stash_count_refs, &stash_count);
 	if (stash_count > 0)
 		status_printf_ln(s, GIT_COLOR_NORMAL,
 				 Q_("Your stash currently has %d entry",
@@ -1212,17 +1218,23 @@
 static void show_am_in_progress(struct wt_status *s,
 				const char *color)
 {
+	int am_empty_patch;
+
 	status_printf_ln(s, color,
 		_("You are in the middle of an am session."));
 	if (s->state.am_empty_patch)
 		status_printf_ln(s, color,
 			_("The current patch is empty."));
 	if (s->hints) {
-		if (!s->state.am_empty_patch)
+		am_empty_patch = s->state.am_empty_patch;
+		if (!am_empty_patch)
 			status_printf_ln(s, color,
 				_("  (fix conflicts and then run \"git am --continue\")"));
 		status_printf_ln(s, color,
 			_("  (use \"git am --skip\" to skip this patch)"));
+		if (am_empty_patch)
+			status_printf_ln(s, color,
+				_("  (use \"git am --allow-empty\" to record this patch as an empty commit)"));
 		status_printf_ln(s, color,
 			_("  (use \"git am --abort\" to restore the original branch)"));
 	}
@@ -2177,6 +2189,18 @@
 }
 
 /*
+ * Print the stash count in a porcelain-friendly format
+ */
+static void wt_porcelain_v2_print_stash(struct wt_status *s)
+{
+	int stash_count = count_stash_entries();
+	char eol = s->null_termination ? '\0' : '\n';
+
+	if (stash_count > 0)
+		fprintf(s->fp, "# stash %d%c", stash_count, eol);
+}
+
+/*
  * Convert various submodule status values into a
  * fixed-length string of characters in the buffer provided.
  */
@@ -2437,6 +2461,9 @@
 	if (s->show_branch)
 		wt_porcelain_v2_print_tracking(s);
 
+	if (s->show_stash)
+		wt_porcelain_v2_print_stash(s);
+
 	for (i = 0; i < s->change.nr; i++) {
 		it = &(s->change.items[i]);
 		d = it->util;
diff --git a/xdiff-interface.c b/xdiff-interface.c
index 75b32ae..2e3a5a2 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -313,6 +313,8 @@
 			die("'%s' is not a boolean", var);
 		if (!strcmp(value, "diff3"))
 			git_xmerge_style = XDL_MERGE_DIFF3;
+		else if (!strcmp(value, "zdiff3"))
+			git_xmerge_style = XDL_MERGE_ZEALOUS_DIFF3;
 		else if (!strcmp(value, "merge"))
 			git_xmerge_style = 0;
 		/*
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index b29deca..72e25a9 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -66,6 +66,7 @@
 
 /* merge output styles */
 #define XDL_MERGE_DIFF3 1
+#define XDL_MERGE_ZEALOUS_DIFF3 2
 
 typedef struct s_mmfile {
 	char *ptr;
diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c
index a4542c0..69689fa 100644
--- a/xdiff/xdiffi.c
+++ b/xdiff/xdiffi.c
@@ -390,12 +390,9 @@
 }
 
 
-static int recs_match(xrecord_t *rec1, xrecord_t *rec2, long flags)
+static int recs_match(xrecord_t *rec1, xrecord_t *rec2)
 {
-	return (rec1->ha == rec2->ha &&
-		xdl_recmatch(rec1->ptr, rec1->size,
-			     rec2->ptr, rec2->size,
-			     flags));
+	return (rec1->ha == rec2->ha);
 }
 
 /*
@@ -759,10 +756,10 @@
  * following group, expand this group to include it. Return 0 on success or -1
  * if g cannot be slid down.
  */
-static int group_slide_down(xdfile_t *xdf, struct xdlgroup *g, long flags)
+static int group_slide_down(xdfile_t *xdf, struct xdlgroup *g)
 {
 	if (g->end < xdf->nrec &&
-	    recs_match(xdf->recs[g->start], xdf->recs[g->end], flags)) {
+	    recs_match(xdf->recs[g->start], xdf->recs[g->end])) {
 		xdf->rchg[g->start++] = 0;
 		xdf->rchg[g->end++] = 1;
 
@@ -780,10 +777,10 @@
  * into a previous group, expand this group to include it. Return 0 on success
  * or -1 if g cannot be slid up.
  */
-static int group_slide_up(xdfile_t *xdf, struct xdlgroup *g, long flags)
+static int group_slide_up(xdfile_t *xdf, struct xdlgroup *g)
 {
 	if (g->start > 0 &&
-	    recs_match(xdf->recs[g->start - 1], xdf->recs[g->end - 1], flags)) {
+	    recs_match(xdf->recs[g->start - 1], xdf->recs[g->end - 1])) {
 		xdf->rchg[--g->start] = 1;
 		xdf->rchg[--g->end] = 0;
 
@@ -833,7 +830,7 @@
 			end_matching_other = -1;
 
 			/* Shift the group backward as much as possible: */
-			while (!group_slide_up(xdf, &g, flags))
+			while (!group_slide_up(xdf, &g))
 				if (group_previous(xdfo, &go))
 					BUG("group sync broken sliding up");
 
@@ -848,7 +845,7 @@
 
 			/* Now shift the group forward as far as possible: */
 			while (1) {
-				if (group_slide_down(xdf, &g, flags))
+				if (group_slide_down(xdf, &g))
 					break;
 				if (group_next(xdfo, &go))
 					BUG("group sync broken sliding down");
@@ -875,7 +872,7 @@
 			 * other file that it can align with.
 			 */
 			while (go.end == go.start) {
-				if (group_slide_up(xdf, &g, flags))
+				if (group_slide_up(xdf, &g))
 					BUG("match disappeared");
 				if (group_previous(xdfo, &go))
 					BUG("group sync broken sliding to match");
@@ -918,7 +915,7 @@
 			}
 
 			while (g.end > best_shift) {
-				if (group_slide_up(xdf, &g, flags))
+				if (group_slide_up(xdf, &g))
 					BUG("best shift unreached");
 				if (group_previous(xdfo, &go))
 					BUG("group sync broken sliding to blank line");
diff --git a/xdiff/xhistogram.c b/xdiff/xhistogram.c
index e694bfd..8079474 100644
--- a/xdiff/xhistogram.c
+++ b/xdiff/xhistogram.c
@@ -88,19 +88,14 @@
 #define REC(env, s, l) \
 	(env->xdf##s.recs[l - 1])
 
-static int cmp_recs(xpparam_t const *xpp,
-	xrecord_t *r1, xrecord_t *r2)
+static int cmp_recs(xrecord_t *r1, xrecord_t *r2)
 {
-	return r1->ha == r2->ha &&
-		xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
-			    xpp->flags);
+	return r1->ha == r2->ha;
+
 }
 
-#define CMP_ENV(xpp, env, s1, l1, s2, l2) \
-	(cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))
-
 #define CMP(i, s1, l1, s2, l2) \
-	(cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))
+	(cmp_recs(REC(i->env, s1, l1), REC(i->env, s2, l2)))
 
 #define TABLE_HASH(index, side, line) \
 	XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 1659edb..fff0b59 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -230,7 +230,7 @@
 	size += xdl_recs_copy(xe1, m->i1, m->chg1, needs_cr, 1,
 			      dest ? dest + size : NULL);
 
-	if (style == XDL_MERGE_DIFF3) {
+	if (style == XDL_MERGE_DIFF3 || style == XDL_MERGE_ZEALOUS_DIFF3) {
 		/* Shared preimage */
 		if (!dest) {
 			size += marker_size + 1 + needs_cr + marker3_size;
@@ -322,6 +322,40 @@
 	return size;
 }
 
+static int recmatch(xrecord_t *rec1, xrecord_t *rec2, unsigned long flags)
+{
+	return xdl_recmatch(rec1->ptr, rec1->size,
+			    rec2->ptr, rec2->size, flags);
+}
+
+/*
+ * Remove any common lines from the beginning and end of the conflicted region.
+ */
+static void xdl_refine_zdiff3_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
+		xpparam_t const *xpp)
+{
+	xrecord_t **rec1 = xe1->xdf2.recs, **rec2 = xe2->xdf2.recs;
+	for (; m; m = m->next) {
+		/* let's handle just the conflicts */
+		if (m->mode)
+			continue;
+
+		while(m->chg1 && m->chg2 &&
+		      recmatch(rec1[m->i1], rec2[m->i2], xpp->flags)) {
+			m->chg1--;
+			m->chg2--;
+			m->i1++;
+			m->i2++;
+		}
+		while (m->chg1 && m->chg2 &&
+		       recmatch(rec1[m->i1 + m->chg1 - 1],
+				rec2[m->i2 + m->chg2 - 1], xpp->flags)) {
+			m->chg1--;
+			m->chg2--;
+		}
+	}
+}
+
 /*
  * Sometimes, changes are not quite identical, but differ in only a few
  * lines. Try hard to show only these few lines as conflicting.
@@ -482,7 +516,22 @@
 	int style = xmp->style;
 	int favor = xmp->favor;
 
-	if (style == XDL_MERGE_DIFF3) {
+	/*
+	 * XDL_MERGE_DIFF3 does not attempt to refine conflicts by looking
+	 * at common areas of sides 1 & 2, because the base (side 0) does
+	 * not match and is being shown.  Similarly, simplification of
+	 * non-conflicts is also skipped due to the skipping of conflict
+	 * refinement.
+	 *
+	 * XDL_MERGE_ZEALOUS_DIFF3, on the other hand, will attempt to
+	 * refine conflicts looking for common areas of sides 1 & 2.
+	 * However, since the base is being shown and does not match,
+	 * it will only look for common areas at the beginning or end
+	 * of the conflict block.  Since XDL_MERGE_ZEALOUS_DIFF3's
+	 * conflict refinement is much more limited in this fashion, the
+	 * conflict simplification will be skipped.
+	 */
+	if (style == XDL_MERGE_DIFF3 || style == XDL_MERGE_ZEALOUS_DIFF3) {
 		/*
 		 * "diff3 -m" output does not make sense for anything
 		 * more aggressive than XDL_MERGE_EAGER.
@@ -603,10 +652,12 @@
 	if (!changes)
 		changes = c;
 	/* refine conflicts */
-	if (XDL_MERGE_ZEALOUS <= level &&
-	    (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
-	     xdl_simplify_non_conflicts(xe1, changes,
-					XDL_MERGE_ZEALOUS < level) < 0)) {
+	if (style == XDL_MERGE_ZEALOUS_DIFF3) {
+		xdl_refine_zdiff3_conflicts(xe1, xe2, changes, xpp);
+	} else if (XDL_MERGE_ZEALOUS <= level &&
+		   (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
+		    xdl_simplify_non_conflicts(xe1, changes,
+					       XDL_MERGE_ZEALOUS < level) < 0)) {
 		xdl_cleanup_merge(changes);
 		return -1;
 	}
diff --git a/xdiff/xprepare.c b/xdiff/xprepare.c
index abeb8fb..4527a4a 100644
--- a/xdiff/xprepare.c
+++ b/xdiff/xprepare.c
@@ -181,15 +181,11 @@
 	if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *))))
 		goto abort;
 
-	if (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF)
-		hbits = hsize = 0;
-	else {
-		hbits = xdl_hashbits((unsigned int) narec);
-		hsize = 1 << hbits;
-		if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *))))
-			goto abort;
-		memset(rhash, 0, hsize * sizeof(xrecord_t *));
-	}
+	hbits = xdl_hashbits((unsigned int) narec);
+	hsize = 1 << hbits;
+	if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *))))
+		goto abort;
+	memset(rhash, 0, hsize * sizeof(xrecord_t *));
 
 	nrec = 0;
 	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
@@ -208,9 +204,7 @@
 			crec->size = (long) (cur - prev);
 			crec->ha = hav;
 			recs[nrec++] = crec;
-
-			if ((XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&
-			    xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
+			if (xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
 				goto abort;
 		}
 	}
@@ -219,10 +213,13 @@
 		goto abort;
 	memset(rchg, 0, (nrec + 2) * sizeof(char));
 
-	if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long))))
-		goto abort;
-	if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long))))
-		goto abort;
+	if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
+	    (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)) {
+		if (!(rindex = xdl_malloc((nrec + 1) * sizeof(*rindex))))
+			goto abort;
+		if (!(ha = xdl_malloc((nrec + 1) * sizeof(*ha))))
+			goto abort;
+	}
 
 	xdf->nrec = nrec;
 	xdf->recs = recs;
@@ -279,8 +276,7 @@
 	enl1 = xdl_guess_lines(mf1, sample) + 1;
 	enl2 = xdl_guess_lines(mf2, sample) + 1;
 
-	if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF &&
-	    xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)
+	if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)
 		return -1;
 
 	if (xdl_prepare_ctx(1, mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
@@ -305,8 +301,7 @@
 		return -1;
 	}
 
-	if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)
-		xdl_free_classifier(&cf);
+	xdl_free_classifier(&cf);
 
 	return 0;
 }