0616617c7e
Call an object's type "unexpected" when the actual type of an object
does not match Git's contextual expectation. For example, a tree entry
whose mode differs from the object's actual type, or a commit's parent
which is not another commit, and so on.
This can manifest itself in various unfortunate ways, including Git
SIGSEGV-ing under specific conditions. Consider the following example:
Git traverses a blob (say, via `git rev-list`), and then tries to read
out a tree-entry which lists that object as something other than a blob.
In this case, `lookup_blob()` will return NULL, and the subsequent
dereference will result in a SIGSEGV.
Introduce tests that present objects of "unexpected" type in the above
fashion to 'git rev-list'. Mark as failures the combinations that are
already broken (i.e., they exhibit the segfault described above). In the
cases that are not broken (i.e., they have NULL-ness checks or similar),
mark these as expecting success.
We might hit an unexpected type in two different ways (imagine we have a
tree entry that claims to be a tree but actually points to a blob):
- when we call lookup_tree(), we might find that we've already seen
the object referenced as a blob, in which case we'd get NULL. We
can exercise this with "git rev-list --objects $blob $tree", which
guarantees that the blob will have been parsed before we look in
the tree. These tests are marked as "seen" in the test script.
- we call lookup_tree() successfully, but when we try to read the
object, we find out it's something else. We construct our tests
such that $blob is not otherwise mentioned in $tree. These tests
are marked as "lone" in the script.
We should check that we behave sensibly in both cases (especially
because it is easy for a malicious actor to provoke one case or the
other).
Co-authored-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
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-.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://public-inbox.org/git/, http://marc.info/?l=git and other archival sites.
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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