a8e7a2bf0f
Prior to 644eb60bd0 (builtin/describe.c: describe a blob,
2017-11-15), we noticed and complained about missing
objects, since they were not valid commits:
$ git describe 0000000000000000000000000000000000000000
fatal: 0000000000000000000000000000000000000000 is not a valid 'commit' object
After that commit, we feed any non-commit to lookup_blob(),
and complain only if it returns NULL. But the lookup_*
functions do not actually look at the on-disk object
database at all. They return an entry from the in-memory
object hash if present (and if it matches the requested
type), and otherwise auto-create a "struct object" of the
requested type.
A missing object would hit that latter case: we create a
bogus blob struct, walk all of history looking for it, and
then exit successfully having produced no output.
One reason nobody may have noticed this is that some related
cases do still work OK:
1. If we ask for a tree by sha1, then the call to
lookup_commit_referecne_gently() would have parsed it,
and we would have its true type in the in-memory object
hash.
2. If we ask for a name that doesn't exist but isn't a
40-hex sha1, then get_oid() would complain before we
even look at the objects at all.
We can fix this by replacing the lookup_blob() call with a
check of the true type via sha1_object_info(). This is not
quite as efficient as we could possibly make this check. We
know in most cases that the object was already parsed in the
earlier commit lookup, so we could call lookup_object(),
which does auto-create, and check the resulting struct's
type (or NULL). However it's not worth the fragility nor
code complexity to save a single object lookup.
The new tests cover this case, as well as that of a
tree-by-sha1 (which does work as described above, but was
not explicitly tested).
Noticed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jeff King <peff@peff.net>
Acked-by: Stefan Beller <sbeller@google.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.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
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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 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