pathspec: add copy_pathspec

Because free_pathspec wants to free "items" pointer in the pathspec
structure, a simple structure assignment is not enough if you want to
copy an existing pathspec into another.  Freeing the original will
damage the copy unless a deep copy is made.

Note that the strings in pathspec->items->match and the array
pathspec->raw[] are still shared between the original and the copy.

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

builtin/mv.c

@@ -15,8 +15,9 @@ static const char * const builtin_mv_usage[] = {
 	NULL
 };
 
-static const char **copy_pathspec(const char *prefix, const char **pathspec,
-				  int count, int base_name)
+static const char **internal_copy_pathspec(const char *prefix,
+					   const char **pathspec,
+					   int count, int base_name)
 {
 	int i;
 	const char **result = xmalloc((count + 1) * sizeof(const char *));
@@ -81,17 +82,17 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 	if (read_cache() < 0)
 		die(_("index file corrupt"));
 
-	source = copy_pathspec(prefix, argv, argc, 0);
+	source = internal_copy_pathspec(prefix, argv, argc, 0);
 	modes = xcalloc(argc, sizeof(enum update_mode));
-	dest_path = copy_pathspec(prefix, argv + argc, 1, 0);
+	dest_path = internal_copy_pathspec(prefix, argv + argc, 1, 0);
 
 	if (dest_path[0][0] == '\0')
 		/* special case: "." was normalized to "" */
-		destination = copy_pathspec(dest_path[0], argv, argc, 1);
+		destination = internal_copy_pathspec(dest_path[0], argv, argc, 1);
 	else if (!lstat(dest_path[0], &st) &&
 			S_ISDIR(st.st_mode)) {
 		dest_path[0] = add_slash(dest_path[0]);
-		destination = copy_pathspec(dest_path[0], argv, argc, 1);
+		destination = internal_copy_pathspec(dest_path[0], argv, argc, 1);
 	} else {
 		if (argc != 1)
 			die("destination '%s' is not a directory", dest_path[0]);

pathspec.c

@@ -249,3 +249,11 @@ const char **get_pathspec(const char *prefix, const char **pathspec)
 		return NULL;
 	return pathspec;
 }
+
+void copy_pathspec(struct pathspec *dst, const struct pathspec *src)
+{
+	*dst = *src;
+	dst->items = xmalloc(sizeof(struct pathspec_item) * dst->nr);
+	memcpy(dst->items, src->items,
+	       sizeof(struct pathspec_item) * dst->nr);
+}

pathspec.h

@@ -18,6 +18,7 @@ struct pathspec {
 };
 
 extern int init_pathspec(struct pathspec *, const char **);
+extern void copy_pathspec(struct pathspec *dst, const struct pathspec *src);
 extern void free_pathspec(struct pathspec *);
 
 extern int limit_pathspec_to_literal(void);