apply: do not leak patches and fragments

In the while loop inside apply_patch, patch and fragments are
dynamically allocated with a calloc. However, only unused patches
are actually freed and the rest are left to leak. Since a list is
actively built up consisting of the used patches, they can simply be
iterated and freed at the end of the function.

In addition, the text in fragments were not freed, primarily because
they mostly point into a patch text that is freed as a whole. But
there are some cases where new piece of memory is allocated and
pointed by a fragment (namely, when handling a binary patch).

Introduce a free_patch bitfield to mark each fragment if its text
needs to be freed, and free patches, fragments and fragment text
that need to be freed when we are done with the input.

Signed-off-by: Jared Hance <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: jhance

builtin/apply.c

@@ -152,8 +152,9 @@ struct fragment {
 	unsigned long oldpos, oldlines;
 	unsigned long newpos, newlines;
 	const char *patch;
+	unsigned free_patch:1,
+		rejected:1;
 	int size;
-	int rejected;
 	int linenr;
 	struct fragment *next;
 };
@@ -195,6 +196,24 @@ struct patch {
 	struct patch *next;
 };
 
+static void free_patch(struct patch *patch)
+{
+	while (patch) {
+		struct patch *patch_next = patch->next;
+		struct fragment *fragment = patch->fragments;
+
+		while (fragment) {
+			struct fragment *fragment_next = fragment->next;
+			if (fragment->patch != NULL && fragment->free_patch)
+				free((char *)fragment->patch);
+			free(fragment);
+			fragment = fragment_next;
+		}
+		free(patch);
+		patch = patch_next;
+	}
+}
+
 /*
  * A line in a file, len-bytes long (includes the terminating LF,
  * except for an incomplete line at the end if the file ends with
@@ -1741,6 +1760,7 @@ static struct fragment *parse_binary_hunk(char **buf_p,
 
 	frag = xcalloc(1, sizeof(*frag));
 	frag->patch = inflate_it(data, hunk_size, origlen);
+	frag->free_patch = 1;
 	if (!frag->patch)
 		goto corrupt;
 	free(data);
@@ -3686,7 +3706,6 @@ static int apply_patch(int fd, const char *filename, int options)
 	struct patch *list = NULL, **listp = &list;
 	int skipped_patch = 0;
 
-	/* FIXME - memory leak when using multiple patch files as inputs */
 	memset(&fn_table, 0, sizeof(struct string_list));
 	patch_input_file = filename;
 	read_patch_file(&buf, fd);
@@ -3711,8 +3730,7 @@ static int apply_patch(int fd, const char *filename, int options)
 			listp = &patch->next;
 		}
 		else {
-			/* perhaps free it a bit better? */
-			free(patch);
+			free_patch(patch);
 			skipped_patch++;
 		}
 		offset += nr;
@@ -3753,6 +3771,7 @@ static int apply_patch(int fd, const char *filename, int options)
 	if (summary)
 		summary_patch_list(list);
 
+	free_patch(list);
 	strbuf_release(&buf);
 	return 0;
 }