[PATCH 6/8] add ref_cmp_full_short() comparing full ref name with a short name

[Steffen Prohaska <prohaska@zib.de>]

ref_cmp_full_short(full_name, short_name) expands short_name according
to the rules documented in git-rev-parse and compares the expanded
name with full_name. It reports a match by returning 0.

This function makes the rules for resolving refs to sha1s available
for string comparison. Before this change, the rules were buried in
get_sha1*() and dwim_ref().

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

Signed-off-by: Steffen Prohaska <prohaska@zib.de>
---
 cache.h     |    1 +
 sha1_name.c |   14 ++++++++++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/cache.h b/cache.h
index 726948b..e1385ac 100644
--- a/cache.h
+++ b/cache.h
@@ -406,6 +406,7 @@ extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 extern char *sha1_to_hex(const unsigned char *sha1);	/* static buffer result! */
 extern int read_ref(const char *filename, unsigned char *sha1);
 extern const char *resolve_ref(const char *path, unsigned char *sha1, int, int *);
+extern int ref_cmp_full_short(const char *full_name, const char *short_name);
 extern int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref);
 extern int dwim_log(const char *str, int len, unsigned char *sha1, char **ref);
 
diff --git a/sha1_name.c b/sha1_name.c
index b820909..2a1e093 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -249,6 +249,20 @@ static const char *ref_fmt[] = {
 	NULL
 };
 
+int ref_cmp_full_short(const char *full_name, const char *short_name)
+{
+	const char **p;
+	const int short_name_len = strlen(short_name);
+
+	for (p = ref_fmt; *p; p++) {
+		if (strcmp(full_name, mkpath(*p, short_name_len, short_name)) == 0) {
+			return 0;
+		}
+	}
+
+	return -1;
+}
+
 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 {
 	const char **p, *r;
-- 
1.5.3.4.1261.g626eb