ls-remote: resurrect pattern limit support

"git ls-remote $remote $name1 $name2..." used to limit the output to
refs that end with one of the $name given from the command line, but
recent rewrite to C forgot to implement that support.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-ls-remote.c

@@ -6,13 +6,43 @@
 static const char ls_remote_usage[] =
 "git-ls-remote [--upload-pack=<git-upload-pack>] [<host>:]<directory>";
 
+/*
+ * pattern is a list of tail-part of accepted refnames.  Is there one
+ * among them that is a suffix of the path?  Directory boundary must
+ * be honored when checking this match.  IOW, patterns "master" and
+ * "sa/master" both match path "refs/hold/sa/master".  On the other
+ * hand, path "refs/hold/foosa/master" is matched by "master" but not
+ * by "sa/master".
+ */
+
+static int tail_match(const char **pattern, const char *path)
+{
+	int pathlen;
+	const char *p;
+
+	if (!*pattern)
+		return 1; /* no restriction */
+
+	for (pathlen = strlen(path); (p = *pattern); pattern++) {
+		int pfxlen = pathlen - strlen(p);
+		if (pfxlen < 0)
+			continue; /* pattern is longer, will never match */
+		if (strcmp(path + pfxlen, p))
+			continue; /* no tail match */
+		if (!pfxlen || path[pfxlen - 1] == '/')
+			return 1; /* fully match at directory boundary */
+	}
+	return 0;
+}
+
 int cmd_ls_remote(int argc, const char **argv, const char *prefix)
 {
 	int i;
 	const char *dest = NULL;
 	int nongit = 0;
 	unsigned flags = 0;
 	const char *uploadpack = NULL;
+	const char **pattern = NULL;
 
 	struct remote *remote;
 	struct transport *transport;
@@ -50,9 +80,9 @@ int cmd_ls_remote(int argc, const char **argv, const char *prefix)
 		break;
 	}
 
-	if (!dest || i != argc - 1)
+	if (!dest)
 		usage(ls_remote_usage);
-
+	pattern = argv + i + 1;
 	remote = nongit ? NULL : remote_get(dest);
 	if (remote && !remote->url_nr)
 		die("remote %s has no configured URL", dest);
@@ -65,10 +95,12 @@ int cmd_ls_remote(int argc, const char **argv, const char *prefix)
 	if (!ref)
 		return 1;
 
-	while (ref) {
-		if (check_ref_type(ref, flags))
-			printf("%s	%s\n", sha1_to_hex(ref->old_sha1), ref->name);
-		ref = ref->next;
+	for ( ; ref; ref = ref->next) {
+		if (!check_ref_type(ref, flags))
+			continue;
+		if (!tail_match(pattern, ref->name))
+			continue;
+		printf("%s	%s\n", sha1_to_hex(ref->old_sha1), ref->name);
 	}
 	return 0;
 }