diffcore: add a pickaxe option to find a specific blob
Sometimes users are given a hash of an object and they want to
identify it further (ex.: Use verify-pack to find the largest blobs,
but what are these? or [1])
One might be tempted to extend git-describe to also work with blobs,
such that `git describe <blob-id>` gives a description as
'<commit-ish>:<path>'. This was implemented at [2]; as seen by the sheer
number of responses (>110), it turns out this is tricky to get right.
The hard part to get right is picking the correct 'commit-ish' as that
could be the commit that (re-)introduced the blob or the blob that
removed the blob; the blob could exist in different branches.
Junio hinted at a different approach of solving this problem, which this
patch implements. Teach the diff machinery another flag for restricting
the information to what is shown. For example:
$ ./git log --oneline --find-object=v2.0.0:Makefile
b2feb64309 Revert the whole "ask curl-config" topic for now
47fbfded53 i18n: only extract comments marked with "TRANSLATORS:"
we observe that the Makefile as shipped with 2.0 was appeared in
v1.9.2-471-g47fbfded53 and in v2.0.0-rc1-5-gb2feb6430b. The
reason why these commits both occur prior to v2.0.0 are evil
merges that are not found using this new mechanism.
[1] https://stackoverflow.com/questions/223678/which-commit-has-this-blob
[2] https://public-inbox.org/git/20171028004419.10139-1-sbeller@google.com/
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diff.h b/diff.h
index 9ec4f82..8a56cac 100644
--- a/diff.h
+++ b/diff.h
@@ -7,6 +7,7 @@
#include "tree-walk.h"
#include "pathspec.h"
#include "object.h"
+#include "oidset.h"
struct rev_info;
struct diff_options;
@@ -173,6 +174,8 @@ struct diff_options {
enum diff_words_type word_diff;
enum diff_submodule_format submodule_format;
+ struct oidset *objfind;
+
/* this is set by diffcore for DIFF_FORMAT_PATCH */
int found_changes;
@@ -325,8 +328,11 @@ extern void diff_setup_done(struct diff_options *);
#define DIFF_PICKAXE_KIND_S 4 /* traditional plumbing counter */
#define DIFF_PICKAXE_KIND_G 8 /* grep in the patch */
+#define DIFF_PICKAXE_KIND_OBJFIND 16 /* specific object IDs */
-#define DIFF_PICKAXE_KINDS_MASK (DIFF_PICKAXE_KIND_S | DIFF_PICKAXE_KIND_G)
+#define DIFF_PICKAXE_KINDS_MASK (DIFF_PICKAXE_KIND_S | \
+ DIFF_PICKAXE_KIND_G | \
+ DIFF_PICKAXE_KIND_OBJFIND)
#define DIFF_PICKAXE_IGNORE_CASE 32
