7384654acf
When `refs_resolve_ref_unsafe()` is called to resolve HEAD, and returns
NULL (e.g., HEAD does not exist as a proper ref), the code falls back to
`repo_get_oid("HEAD")` to try to resolve the OID directly. If that
succeeds, execution continues with `head` still set to NULL.
Later, that variable is passed to `repo_get_oid()` and `starts_with()`,
both of which would dereference the NULL pointer.
A concrete trigger for `refs_resolve_ref_unsafe()` returning NULL while
`repo_get_oid()` succeeds could not be constructed against the ref
backends currently in the tree; the naive case (a symbolic HEAD pointing
at a nonexistent branch, in either the files or the reftable backend)
fails in both calls consistently and returns via the existing
`error(_("bad HEAD - I need a HEAD"))` path. Coverity, however, flags
the leftover use of `head` after the outer `if (!head)` on a formal
reading: `head` is still NULL at that point, and both `starts_with(head,
...)` and the second `repo_get_oid(..., head, ...)` in the else-branch
would dereference it if that state were ever reached.
Removing the outer check would risk regressing to a crash if a future
ref backend ever manages to hit the "returns NULL for HEAD but has a
valid OID for HEAD" state. Assigning the literal string "HEAD" as a
safe fallback documents the intent and satisfies the analyzer without
changing behavior in any code path we can currently reach.
Assisted-by: Claude Opus 4.7
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
To subscribe to the list, send an email to git+subscribe@vger.kernel.org (see https://subspace.kernel.org/subscribing.html for details). The mailing list archives are available at https://lore.kernel.org/git/, https://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
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