refs: add expand_ref()

This is basically dwim_ref() without @{} support. To be used on the
server side where we want to expand abbreviated to full ref names and
nothing else. The first user is "git clone/fetch --shallow-exclude".
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

refs.c

@@ -392,6 +392,13 @@ static char *substitute_branch_name(const char **string, int *len)
 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 {
 	char *last_branch = substitute_branch_name(&str, &len);
+	int   refs_found  = expand_ref(str, len, sha1, ref);
+	free(last_branch);
+	return refs_found;
+}
+
+int expand_ref(const char *str, int len, unsigned char *sha1, char **ref)
+{
 	const char **p, *r;
 	int refs_found = 0;
 
@@ -417,7 +424,6 @@ int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 			warning("ignoring broken ref %s.", fullref);
 		}
 	}
-	free(last_branch);
 	return refs_found;
 }
 

refs.h

@@ -90,6 +90,7 @@ extern int resolve_gitlink_ref(const char *path, const char *refname, unsigned c
  */
 extern int refname_match(const char *abbrev_name, const char *full_name);
 
+extern int expand_ref(const char *str, int len, unsigned char *sha1, char **ref);
 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);