87264b7dde
Our current pack index v3 format uses 4-byte integers to find the trailer of the file. This effectively means that the file cannot be much larger than 2^32. While this might at first seem to be okay, we expect that each object will have at least 64 bytes worth of data, which means that no more than about 67 million objects can be stored. Again, this might seem fine, but unfortunately, we know of many users who attempt to create repos with extremely large numbers of commits to get a "high score," and we've already seen repositories with at least 55 million commits. In the interests of gracefully handling repositories even for these well-intentioned but ultimately misguided users, let's change these lengths to 8 bytes. For the checksums at the end of the file, we're producing 32-byte SHA-256 checksums because that's what we already do with pack index v2 and SHA-256. Truncating SHA-256 doesn't pose any actual security problems other than those related to the reduced size, but our pack checksum must already be 32 bytes (since SHA-256 packs have 32-byte checksums) and it simplifies the code to use the existing hashfile logic for these cases for the index checksum as well. In addition, even though we may not need cryptographic security for the index checksum, we'd like to avoid arguments from auditors and such for organizations that may have compliance or security requirements. Using the simple, boring choice of the full SHA-256 hash avoids all possible discussion related to hash truncation and removes impediments for these organizations. Note that we do not yet have a pack index v3 implementation in Git, so it should be fine to change this format. However, such an implementation has been written for future inclusion following this format. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.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).
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