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In midx_pack_order(), we compute for each bitampped pack the first bit to correspond to an object in that pack, along with how many bits were assigned to object(s) in that pack. Initially, each bitmap_nr value is set to zero, and each bitmap_pos value is set to the sentinel BITMAP_POS_UNKNOWN. This is done to ensure that there are no packs who have an unknown bit position but a somehow non-zero number of objects (cf. `write_midx_bitmapped_packs()` in midx-write.c). Once the pack order is fully determined, midx_pack_order() sets the bitmap_pos field for any bitmapped packs to zero if they are still listed as BITMAP_POS_UNKNOWN. However, we enumerate the bitmapped packs in order of `ctx->pack_perm`. This is fine for existing cases, since the only time the `ctx->pack_perm` array holds a value outside of the addressable range of `ctx->info` is when there are expired packs, which only occurs via 'git multi-pack-index expire', which does not support writing MIDX bitmaps. As a result, the range of ctx->pack_perm covers all values in [0, `ctx->nr`), so enumerating in this order isn't an issue. A future change necessary for compaction will complicate this further by introducing a wrapper around the `ctx->pack_perm` array, which turns the given `pack_int_id` into one that is relative to the lower end of the compaction range. As a result, indexing into `ctx->pack_perm` through this helper, say, with "0" will produce a crash when the lower end of the compaction range has >0 pack(s) in its base layer, since the subtraction will wrap around the 32-bit unsigned range, resulting in an uninitialized read. But the process is completely unnecessary in the first place: we are enumerating all values of `ctx->info`, and there is no reason to process them in a different order than they appear in memory. Index `ctx->info` directly to reflect that. Signed-off-by: Taylor Blau <me@ttaylorr.com> 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