clone: allow to clone from .git file

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/clone.c

@@ -101,9 +101,26 @@ static char *get_repo_path(const char *repo, int *is_bundle)
 	for (i = 0; i < ARRAY_SIZE(suffix); i++) {
 		const char *path;
 		path = mkpath("%s%s", repo, suffix[i]);
-		if (is_directory(path)) {
+		if (stat(path, &st))
+			continue;
+		if (S_ISDIR(st.st_mode)) {
 			*is_bundle = 0;
 			return xstrdup(absolute_path(path));
+		} else if (S_ISREG(st.st_mode) && st.st_size > 8) {
+			/* Is it a "gitfile"? */
+			char signature[8];
+			int len, fd = open(path, O_RDONLY);
+			if (fd < 0)
+				continue;
+			len = read_in_full(fd, signature, 8);
+			close(fd);
+			if (len != 8 || strncmp(signature, "gitdir: ", 8))
+				continue;
+			path = read_gitfile(path);
+			if (path) {
+				*is_bundle = 0;
+				return xstrdup(absolute_path(path));
+			}
 		}
 	}
 

t/t5601-clone.sh

@@ -202,6 +202,10 @@ test_expect_success 'clone separate gitdir: output' '
 	test_cmp expected dst/.git
 '
 
+test_expect_success 'clone from .git file' '
+	git clone dst/.git dst2
+'
+
 test_expect_success 'clone separate gitdir where target already exists' '
 	rm -rf dst &&
 	test_must_fail git clone --separate-git-dir realgitdir src dst