Shawn O. PearceSometimes scripts want (or need) the annotated tag name that exactly matches a specific commit, or no tag at all. In such cases it can be difficult to determine if the output of `git describe $commit` is a real tag name or a tag+abbreviated commit. A common idiom is to run git-describe twice:
if test $(git describe $commit) = $(git describe --abbrev=0 $commit) ...
but this is a huge waste of time if the caller is just going to pick a different method to describe $commit or abort because it is not exactly an annotated tag.
Setting the maximum number of candidates to 0 allows the caller to ask for only a tag that directly points at the supplied commit, or to have git-describe abort if no such item exists.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org> --- Documentation/git-describe.txt | 5 +++++ builtin-describe.c | 8 ++++++-- 2 files changed, 11 insertions(+), 2 deletions(-)
Show changes to 2 files +11 −2
Documentation/git-describe.txt, builtin-describe.c
diff --git a/Documentation/git-describe.txt b/Documentation/git-describe.txt index 1c3dfb4..fbb40a2 100644 --- a/Documentation/git-describe.txt +++ b/Documentation/git-describe.txt @@ -45,6 +45,11 @@ OPTIONS candidates to describe the input committish consider up to <n> candidates. Increasing <n> above 10 will take slightly longer but may produce a more accurate result. + An <n> of 0 will cause only exact matches to be output. + +--exact-match:: + Only output exact matches (a tag directly references the + supplied commit). This is a synonym for --candidates=0. --debug:: Verbosely display information about the searching strategy diff --git a/builtin-describe.c b/builtin-describe.c index 9c958bd..05e309f 100644 --- a/builtin-describe.c +++ b/builtin-describe.c @@ -174,6 +174,8 @@ static void describe(const char *arg, int last_one) return; } + if (!max_candidates) + die("no tag exactly matches '%s'", sha1_to_hex(cmit->object.sha1)); if (debug) fprintf(stderr, "searching to describe %s\n", arg); @@ -270,6 +272,8 @@ int cmd_describe(int argc, const char **argv, const char *prefix) OPT_BOOLEAN(0, "all", &all, "use any ref in .git/refs"), OPT_BOOLEAN(0, "tags", &tags, "use any tag in .git/refs/tags"), OPT__ABBREV(&abbrev), + OPT_SET_INT(0, "exact-match", &max_candidates, + "only output exact matches", 0), OPT_INTEGER(0, "candidates", &max_candidates, "consider <n> most recent tags (default: 10)"), OPT_STRING(0, "match", &pattern, "pattern", @@ -278,8 +282,8 @@ int cmd_describe(int argc, const char **argv, const char *prefix) }; argc = parse_options(argc, argv, options, describe_usage, 0); - if (max_candidates < 1) - max_candidates = 1; + if (max_candidates < 0) + max_candidates = 0; else if (max_candidates > MAX_TAGS) max_candidates = MAX_TAGS;
-- 1.5.4.3.295.g6b554
