e66077ae45
Users can ask git-for-each-ref(1) to peel tags and return information of
the tagged object by adding an asterisk to the format, like for example
"%(*$objectname)". If so, git-for-each-ref(1) peels that object to the
first non-tag object and then returns its values.
As mentioned in preceding commits, it can happen that the tagged object
type and the claimed object type differ, effectively resulting in a
corrupt tag. git-for-each-ref(1) would notice this mismatch, print an
error and then bail out when trying to peel the tag.
But we only notice this corruption in some very specific edge cases!
While we have a test in "t/for-each-ref-tests.sh" that verifies the
above scenario, this test is specifically crafted to detect the issue at
hand. Namely, we create two tags:
- One tag points to a specific object with the correct type.
- The other tag points to the *same* object with a different type.
The fact that both tags point to the same object is important here:
`peel_object()` wouldn't notice the corruption if the tagged objects
were different.
The root cause is that `peel_object()` calls `lookup_${type}()`
eventually, where the type is the same type declared in the tag object.
Consequently, when we have two tags pointing to the same object but with
different declared types we'll call two different lookup functions. The
first lookup will store the object with an unverified type A, whereas
the second lookup will try to look up the object with a different
unverified type B. And it is only now that we notice the discrepancy in
object types, even though type A could've already been the wrong type.
Fix the issue by verifying the object type in `populate_value()`. With
this change we'll also notice type mismatches when only dereferencing a
tag once.
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.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).
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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