3f018ec716
Fast-import stores its marks in a trie-like structure made of mark_set
structs. Each struct has a fixed size (1024). If our id number is too
large to fit in the struct, then we allocate a new struct which shifts
the id number by 10 bits. Our original struct becomes a child node
of this new layer, and the new struct becomes the top level of the trie.
This scheme was broken by ddddf8d7e2 (fast-import: permit reading
multiple marks files, 2020-02-22). Before then, we had a top-level
"marks" pointer, and the push-down worked by assigning the new top-level
struct to "marks". But after that commit, insert_mark() takes a pointer
to the mark_set, rather than using the global "marks". It continued to
assign to the global "marks" variable during the push down, which was
wrong for two reasons:
- we added a call in option_rewrite_submodules() which uses a separate
mark set; pushing down on "marks" is outright wrong here. We'd
corrupt the "marks" set, and we'd fail to correctly store any
submodule mappings with an id over 1024.
- the other callers passed "marks", but the push-down was still wrong.
In read_mark_file(), we take the pointer to the mark_set as a
parameter. So even though insert_mark() was updating the global
"marks", the local pointer we had in read_mark_file() was not
updated. As a result, we'd add a new level when needed, but then the
next call to insert_mark() wouldn't see it! It would then allocate a
new layer, which would also not be seen, and so on. Lookups for the
lost layers obviously wouldn't work, but before we even hit any
lookup stage, we'd generally run out of memory and die.
Our tests didn't notice either of these cases because they didn't have
enough marks to trigger the push-down behavior. The new tests in t9304
cover both cases (and fail without this patch).
We can solve the problem by having insert_mark() take a pointer-to-pointer
of the top-level of the set. Then our push down can assign to it in a
way that the caller actually sees. Note the subtle reordering in
option_rewrite_submodules(). Our call to read_mark_file() may modify our
top-level set pointer, so we have to wait until after it returns to
assign its value into the string_list.
Reported-by: Sergey Brester <serg.brester@sebres.de>
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.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). To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://lore.kernel.org/git/, http://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