973a0373ff
In prepare_bases() we do a custom revision walk, separate from the main
format-patch walk. After we finish, we fail to call release_revisions(),
possibly leaking its contents.
We failed to notice it so far because the revision machinery doesn't
always allocate. But at least one case can trigger the leak: if a commit
graph is present, then the topo-walk allocates revs.topo_walk_info and
some associated data structures. You can see it in the test suite by
running:
make SANITIZE=leak
cd t
GIT_TEST_COMMIT_GRAPH=1 ./t4014-format-patch.sh
which yields many entries like:
==git==3687620==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 200 byte(s) in 1 object(s) allocated from:
#0 0x7f4ccba185cb in malloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:74
#1 0x55cd452cdd0b in do_xmalloc wrapper.c:55
#2 0x55cd452cdd9d in xmalloc wrapper.c:76
#3 0x55cd45255473 in init_topo_walk revision.c:3845
#4 0x55cd45255bef in prepare_revision_walk revision.c:4017
#5 0x55cd44ffec40 in prepare_bases builtin/log.c:1872
#6 0x55cd450010ec in cmd_format_patch builtin/log.c:2439
The un-released rev_info has been there since the code was added in
fa2ab86d18 (format-patch: add '--base' option to record base tree info,
2016-04-26), but back then we didn't even have a way to release rev_info
resources! The actual leak probably started around f0d9cc4196
(revision.c: begin refactoring --topo-order logic, 2018-11-01), but it's
hard to bisect because there were so many other unrelated leaks back
then.
So I'm not sure exactly when the leak started beyond "long ago", but it
is easy-ish to find now (since we've plugged all those other leaks) and
the solution is clear.
I didn't add a new test since we can demonstrate it with the existing
ones, but it does require tweaking a test variable. We might consider
ways to get more automatic leak-checking coverage there, but I think it
should be done outside of this fix.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.adoc to get started, then see
Documentation/giteveryday.adoc for a useful minimum set of commands, and
Documentation/git-<commandname>.adoc for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.adoc
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).
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The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks