pathspec: copy and free owned memory

The 'original' string entry in a pathspec_item is only duplicated some
of the time, instead always make a copy of the original and take
ownership of the memory.

Since both 'match' and 'original' string entries in a pathspec_item are
owned by the pathspec struct, they need to be freed when clearing the
pathspec struct (in 'clear_pathspec()') and duplicated when copying the
pathspec struct (in 'copy_pathspec()').

Also change the type of 'match' and 'original' to 'char *' in order to
more explicitly show the ownership of the memory.

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

pathspec.c

@@ -259,8 +259,9 @@ static unsigned prefix_pathspec(struct pathspec_item *item,
 		}
 		strbuf_addstr(&sb, match);
 		item->original = strbuf_detach(&sb, NULL);
-	} else
-		item->original = elt;
+	} else {
+		item->original = xstrdup(elt);
+	}
 	item->len = strlen(item->match);
 	item->prefix = prefixlen;
 
@@ -388,8 +389,8 @@ void parse_pathspec(struct pathspec *pathspec,
 			die("BUG: PATHSPEC_PREFER_CWD requires arguments");
 
 		pathspec->items = item = xcalloc(1, sizeof(*item));
-		item->match = prefix;
-		item->original = prefix;
+		item->match = xstrdup(prefix);
+		item->original = xstrdup(prefix);
 		item->nowildcard_len = item->len = strlen(prefix);
 		item->prefix = item->len;
 		pathspec->nr = 1;
@@ -453,13 +454,27 @@ void parse_pathspec(struct pathspec *pathspec,
 
 void copy_pathspec(struct pathspec *dst, const struct pathspec *src)
 {
+	int i;
+
 	*dst = *src;
 	ALLOC_ARRAY(dst->items, dst->nr);
 	COPY_ARRAY(dst->items, src->items, dst->nr);
+
+	for (i = 0; i < dst->nr; i++) {
+		dst->items[i].match = xstrdup(src->items[i].match);
+		dst->items[i].original = xstrdup(src->items[i].original);
+	}
 }
 
 void clear_pathspec(struct pathspec *pathspec)
 {
+	int i;
+
+	for (i = 0; i < pathspec->nr; i++) {
+		free(pathspec->items[i].match);
+		free(pathspec->items[i].original);
+	}
 	free(pathspec->items);
 	pathspec->items = NULL;
+	pathspec->nr = 0;
 }

pathspec.h

@@ -25,8 +25,8 @@ struct pathspec {
 	unsigned magic;
 	int max_depth;
 	struct pathspec_item {
-		const char *match;
-		const char *original;
+		char *match;
+		char *original;
 		unsigned magic;
 		int len, prefix;
 		int nowildcard_len;