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| author | Stefan Beller <sbeller@google.com> | 2017-11-15 18:00:39 -0800 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2017-12-19 11:17:16 -0800 |
| commit | 644eb60bd01a15f665b63774fd80e3b6316073a1 (patch) | |
| tree | 67e1d0cd9e08fa002a71e25571eaa30ab8ff6efc /Documentation | |
| parent | 4dbc59a4cce418ff8428a9d2ecd67c34ca50db56 (diff) | |
| download | git-644eb60bd01a15f665b63774fd80e3b6316073a1.tar.gz | |
builtin/describe.c: describe a blob
Sometimes users are given a hash of an object and they want to
identify it further (ex.: Use verify-pack to find the largest blobs,
but what are these? or [1])
When describing commits, we try to anchor them to tags or refs, as these
are conceptually on a higher level than the commit. And if there is no ref
or tag that matches exactly, we're out of luck. So we employ a heuristic
to make up a name for the commit. These names are ambiguous, there might
be different tags or refs to anchor to, and there might be different
path in the DAG to travel to arrive at the commit precisely.
When describing a blob, we want to describe the blob from a higher layer
as well, which is a tuple of (commit, deep/path) as the tree objects
involved are rather uninteresting. The same blob can be referenced by
multiple commits, so how we decide which commit to use? This patch
implements a rather naive approach on this: As there are no back pointers
from blobs to commits in which the blob occurs, we'll start walking from
any tips available, listing the blobs in-order of the commit and once we
found the blob, we'll take the first commit that listed the blob. For
example
git describe --tags v0.99:Makefile
conversion-901-g7672db20c2:Makefile
tells us the Makefile as it was in v0.99 was introduced in commit 7672db20.
The walking is performed in reverse order to show the introduction of a
blob rather than its last occurrence.
[1] https://stackoverflow.com/questions/223678/which-commit-has-this-blob
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/git-describe.txt | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/Documentation/git-describe.txt b/Documentation/git-describe.txt index c924c945ba..e027fb8c4b 100644 --- a/Documentation/git-describe.txt +++ b/Documentation/git-describe.txt @@ -3,14 +3,14 @@ git-describe(1) NAME ---- -git-describe - Describe a commit using the most recent tag reachable from it - +git-describe - Give an object a human readable name based on an available ref SYNOPSIS -------- [verse] 'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] [<commit-ish>...] 'git describe' [--all] [--tags] [--contains] [--abbrev=<n>] --dirty[=<mark>] +'git describe' <blob> DESCRIPTION ----------- @@ -24,6 +24,12 @@ By default (without --all or --tags) `git describe` only shows annotated tags. For more information about creating annotated tags see the -a and -s options to linkgit:git-tag[1]. +If the given object refers to a blob, it will be described +as `<commit-ish>:<path>`, such that the blob can be found +at `<path>` in the `<commit-ish>`, which itself describes the +first commit in which this blob occurs in a reverse revision walk +from HEAD. + OPTIONS ------- <commit-ish>...:: @@ -186,6 +192,14 @@ selected and output. Here fewest commits different is defined as the number of commits which would be shown by `git log tag..input` will be the smallest number of commits possible. +BUGS +---- + +Tree objects as well as tag objects not pointing at commits, cannot be described. +When describing blobs, the lightweight tags pointing at blobs are ignored, +but the blob is still described as <committ-ish>:<path> despite the lightweight +tag being favorable. + GIT --- Part of the linkgit:git[1] suite |