compat: auto-detect if zlib has uncompress2()
We have a copy of uncompress2() implementation in compat/ so that we
can build with an older version of zlib that lack the function, and
the build procedure selects if it is used via the NO_UNCOMPRESS2
$(MAKE) variable. This is yet another "annoying" knob the porters
need to tweak on platforms that are not common enough to have the
default set in the config.mak.uname file.
Attempt to instead ask the system header <zlib.h> to decide if we
need the compatibility implementation. This is a deviation from the
way we have been handling the "compatiblity" features so far, and if
it can be done cleanly enough, it could work as a model for features
that need compatibility definition we discover in the future. With
that goal in mind, avoid expedient but ugly hacks, like shoving the
code that is conditionally compiled into an unrelated .c file, which
may not work in future cases---instead, take an approach that uses a
file that is independently compiled and stands on its own.
Compile and link compat/zlib-uncompress2.c file unconditionally, but
conditionally hide the implementation behind #if/#endif when zlib
version is 1.2.9 or newer, and unconditionally archive the resulting
object file in the libgit.a to be picked up by the linker.
There are a few things to note in the shape of the code base after
this change:
- We no longer use NO_UNCOMPRESS2 knob; if the system header
<zlib.h> claims a version that is more cent than the library
actually is, this would break, but it is easy to add it back when
we find such a system.
- The object file compat/zlib-uncompress2.o is always compiled and
archived in libgit.a, just like a few other compat/ object files
already are.
- The inclusion of <zlib.h> is done in <git-compat-util.h>; we used
to do so from <cache.h> which includes <git-compat-util.h> as the
first thing it does, so from the *.c codes, there is no practical
change.
- Until objects in libgit.a that is already used gains a reference
to the function, the reftable code will be the only one that
wants it, so libgit.a on the linker command line needs to appear
once more at the end to satisify the mutual dependency.
- Beat found a trick used by OpenSSL to avoid making the
conditionally-compiled object truly empty (apparently because
they had to deal with compilers that do not want to see an
effectively empty input file). Our compat/zlib-uncompress2.c
file borrows the same trick for portabilty.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Helped-by: Beat Bolli <dev+git@drbeat.li>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Makefile b/Makefile
index 5580859..f194b2a 100644
--- a/Makefile
+++ b/Makefile
@@ -256,8 +256,6 @@
#
# 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)
#
@@ -862,6 +860,7 @@
LIB_OBJS += commit.o
LIB_OBJS += compat/obstack.o
LIB_OBJS += compat/terminal.o
+LIB_OBJS += compat/zlib-uncompress2.o
LIB_OBJS += config.o
LIB_OBJS += connect.o
LIB_OBJS += connected.o
@@ -1194,7 +1193,8 @@
THIRD_PARTY_SOURCES += sha1collisiondetection/%
THIRD_PARTY_SOURCES += sha1dc/%
-GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB)
+# xdiff and reftable libs may in turn depend on what is in libgit.a
+GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(LIB_FILE)
EXTLIBS =
GIT_USER_AGENT = git/$(GIT_VERSION)
@@ -1726,11 +1726,6 @@
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
diff --git a/cache.h b/cache.h
index 281f00a..3a0142a 100644
--- a/cache.h
+++ b/cache.h
@@ -18,7 +18,6 @@
#include "repository.h"
#include "mem-pool.h"
-#include <zlib.h>
typedef struct git_zstream {
z_stream z;
unsigned long avail_in;
diff --git a/ci/lib.sh b/ci/lib.sh
index 9d28ab5..cbc2f8f 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -197,7 +197,6 @@
case "$jobname" in
linux32)
CC=gcc
- MAKEFLAGS="$MAKEFLAGS NO_UNCOMPRESS2=1"
;;
linux-musl)
CC=gcc
diff --git a/compat/zlib-uncompress2.c b/compat/zlib-uncompress2.c
index 722610b..77a1b08 100644
--- a/compat/zlib-uncompress2.c
+++ b/compat/zlib-uncompress2.c
@@ -1,3 +1,6 @@
+#include "git-compat-util.h"
+
+#if ZLIB_VERNUM < 0x1290
/* taken from zlib's uncompr.c
commit cacf7f1d4e3d44d871b605da3b647f07d718623f
@@ -8,16 +11,11 @@
*/
-#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 */
/* ===========================================================================
@@ -93,3 +91,6 @@ int ZEXPORT uncompress2 (
err == Z_BUF_ERROR && left + stream.avail_out ? Z_DATA_ERROR :
err;
}
+#else
+static void *dummy_variable = &dummy_variable;
+#endif
diff --git a/config.mak.uname b/config.mak.uname
index c48db45..92ea00c 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -66,7 +66,6 @@
# centos7/rhel7 provides gcc 4.8.5 and zlib 1.2.7.
ifneq ($(findstring .el7.,$(uname_R)),)
BASIC_CFLAGS += -std=c99
- NO_UNCOMPRESS2 = YesPlease
endif
endif
ifeq ($(uname_S),GNU/kFreeBSD)
@@ -266,10 +265,6 @@
FILENO_IS_A_MACRO = UnfortunatelyYes
endif
ifeq ($(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
@@ -525,7 +520,6 @@
endif
endif
ifeq ($(uname_S),Minix)
- NO_UNCOMPRESS2 = YesPlease
NO_IPV6 = YesPlease
NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease
NO_NSEC = YesPlease
@@ -581,7 +575,6 @@
NO_SETENV = YesPlease
NO_UNSETENV = YesPlease
NO_MKDTEMP = YesPlease
- NO_UNCOMPRESS2 = YesPlease
# Currently libiconv-1.9.1.
OLD_ICONV = UnfortunatelyYes
NO_REGEX = NeedsStartEnd
diff --git a/configure.ac b/configure.ac
index d60d494..5ee25ec 100644
--- a/configure.ac
+++ b/configure.ac
@@ -664,22 +664,9 @@
NO_DEFLATE_BOUND=yes])
LIBS="$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/git-compat-util.h b/git-compat-util.h
index 1229c82..ea111a7 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1386,6 +1386,18 @@ void unleak_memory(const void *ptr, size_t len);
#define UNLEAK(var) do {} while (0)
#endif
+#define z_const
+#include <zlib.h>
+
+#if ZLIB_VERNUM < 0x1290
+/*
+ * This is uncompress2, which is only available in zlib >= 1.2.9
+ * (released as of early 2017). See compat/zlib-uncompress2.c.
+ */
+int uncompress2(Bytef *dest, uLongf *destLen, const Bytef *source,
+ uLong *sourceLen);
+#endif
+
/*
* This include must come after system headers, since it introduces macros that
* replace system names.
diff --git a/reftable/system.h b/reftable/system.h
index 4907306..18f9207 100644
--- a/reftable/system.h
+++ b/reftable/system.h
@@ -16,17 +16,6 @@ license that can be found in the LICENSE file or at
#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
