Allow cloning to an existing empty directory

The die() message updated accordingly.

The previous behaviour was to only allow cloning when the destination
directory doesn't exist.

[jc: added trivial tests]

Signed-off-by: Alexander Potashev <aspotashev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-clone.c

@@ -357,6 +357,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	struct stat buf;
 	const char *repo_name, *repo, *work_tree, *git_dir;
 	char *path, *dir;
+	int dest_exists;
 	const struct ref *refs, *head_points_at, *remote_head, *mapped_refs;
 	struct strbuf key = STRBUF_INIT, value = STRBUF_INIT;
 	struct strbuf branch_top = STRBUF_INIT, reflog_msg = STRBUF_INIT;
@@ -406,8 +407,10 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 		dir = guess_dir_name(repo_name, is_bundle, option_bare);
 	strip_trailing_slashes(dir);
 
-	if (!stat(dir, &buf))
-		die("destination directory '%s' already exists.", dir);
+	dest_exists = !stat(dir, &buf);
+	if (dest_exists && !is_empty_dir(dir))
+		die("destination path '%s' already exists and is not "
+			"an empty directory.", dir);
 
 	strbuf_addf(&reflog_msg, "clone: from %s", repo);
 
@@ -431,7 +434,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 		if (safe_create_leading_directories_const(work_tree) < 0)
 			die("could not create leading directories of '%s': %s",
 					work_tree, strerror(errno));
-		if (mkdir(work_tree, 0755))
+		if (!dest_exists && mkdir(work_tree, 0755))
 			die("could not create work tree dir '%s': %s.",
 					work_tree, strerror(errno));
 		set_git_work_tree(work_tree);

dir.c

@@ -777,6 +777,25 @@ int is_inside_dir(const char *dir)
 	return get_relative_cwd(buffer, sizeof(buffer), dir) != NULL;
 }
 
+int is_empty_dir(const char *path)
+{
+	DIR *dir = opendir(path);
+	struct dirent *e;
+	int ret = 1;
+
+	if (!dir)
+		return 0;
+
+	while ((e = readdir(dir)) != NULL)
+		if (!is_dot_or_dotdot(e->d_name)) {
+			ret = 0;
+			break;
+		}
+
+	closedir(dir);
+	return ret;
+}
+
 int remove_dir_recursively(struct strbuf *path, int only_empty)
 {
 	DIR *dir = opendir(path->buf);

dir.h

@@ -84,6 +84,8 @@ static inline int is_dot_or_dotdot(const char *name)
 		 (name[1] == '.' && name[2] == '\0')));
 }
 
+extern int is_empty_dir(const char *dir);
+
 extern void setup_standard_excludes(struct dir_struct *dir);
 extern int remove_dir_recursively(struct strbuf *path, int only_empty);
 

t/t5601-clone.sh

@@ -125,4 +125,23 @@ test_expect_success 'clone to destination with extra trailing /' '
 
 '
 
+test_expect_success 'clone to an existing empty directory' '
+	mkdir target-3 &&
+	git clone src target-3 &&
+	T=$( cd target-3 && git rev-parse HEAD ) &&
+	S=$( cd src && git rev-parse HEAD ) &&
+	test "$T" = "$S"
+'
+
+test_expect_success 'clone to an existing non-empty directory' '
+	mkdir target-4 &&
+	>target-4/Fakefile &&
+	test_must_fail git clone src target-4
+'
+
+test_expect_success 'clone to an existing path' '
+	>target-5 &&
+	test_must_fail git clone src target-5
+'
+
 test_done