add refname_match()

We use at least two rulesets for matching abbreviated refnames with
full refnames (starting with 'refs/').  git-rev-parse and git-fetch
use slightly different rules.

This commit introduces a new function refname_match
(const char *abbrev_name, const char *full_name, const char **rules).

abbrev_name is expanded using the rules and matched against full_name.
If a match is found the function returns true.  rules is a NULL-terminate
list of format patterns with "%.*s", for example:

    const char *ref_rev_parse_rules[] = {
               "%.*s",
               "refs/%.*s",
               "refs/tags/%.*s",
               "refs/heads/%.*s",
               "refs/remotes/%.*s",
               "refs/remotes/%.*s/HEAD",
               NULL
    };

Asterisks are included in the format strings because this is the form
required in sha1_name.c.  Sharing the list with the functions there is
a good idea to avoid duplicating the rules.  Hopefully this
facilitates unified matching rules in the future.

This commit makes the rules used by rev-parse for resolving refs to
sha1s available for string comparison.  Before this change, the rules
were buried in get_sha1*() and dwim_ref().

A follow-up commit will refactor the rules used by fetch.

refname_match() will be used for matching refspecs in git-send-pack.

Thanks to Daniel Barkalow <barkalow@iabervon.org> for pointing
out that ref_matches_abbrev in remote.c solves a similar problem
and care should be taken to avoid confusion.

Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/refs.c b/refs.c
index ae53254..fc26a93 100644
--- a/refs.c
+++ b/refs.c
@@ -643,6 +643,30 @@ int check_ref_format(const char *ref)
 	}
 }
 
+const char *ref_rev_parse_rules[] = {
+	"%.*s",
+	"refs/%.*s",
+	"refs/tags/%.*s",
+	"refs/heads/%.*s",
+	"refs/remotes/%.*s",
+	"refs/remotes/%.*s/HEAD",
+	NULL
+};
+
+int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
+{
+	const char **p;
+	const int abbrev_name_len = strlen(abbrev_name);
+
+	for (p = rules; *p; p++) {
+		if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
 static struct ref_lock *verify_lock(struct ref_lock *lock,
 	const unsigned char *old_sha1, int mustexist)
 {