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a0851cece5
The `validate_headref()` function takes a path to a supposed "HEAD" file and checks whether its format is something that we understand. It is used as part of our repository discovery to check whether a specific directory is a Git directory or not. Part of the validation is a check for a detached HEAD that contains a plain object ID. To do this validation we use `get_oid_hex()`, which relies on `the_hash_algo`. At this point in time the hash algo cannot yet be initialized though because we didn't yet read the Git config. Consequently, it will always be the SHA1 hash algorithm. In practice this works alright because `get_oid_hex()` only ends up checking whether the prefix of the buffer is a valid object ID. And because SHA1 is shorter than SHA256, the function will successfully parse SHA256 object IDs, as well. It is somewhat fragile though and not really the intent to only check for SHA1. With this in mind, harden the code to use `get_oid_hex_any()` to check whether the "HEAD" file parses as any known hash. One might be hard pressed to tighten the check even further and fully validate the file contents, not only the prefix. In practice though that wouldn't make a lot of sense as it could be that the repository uses a hash function that produces longer hashes than SHA256, but which the current version of Git doesn't understand yet. We'd still want to detect the repository as proper Git repository in that case, and we will fail eventually with a proper error message that the hash isn't understood when trying to set up the repository format. It follows that we could just leave the current code intact, as in practice the code change doesn't have any user visible impact. But it also prepares us for `the_hash_algo` being unset when there is no repository. Signed-off-by: Patrick Steinhardt <ps@pks.im> 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.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-<commandname>.txt 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.txt
(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