[PATCH] Fix libxenstore memory leak when USE_PTHREAD is not defined, V2

[Andres Lagar-Cavilla <andres@lagarcavilla.org>]

 tools/xenstore/xs.c |  17 +++++++++++++----
 1 files changed, 13 insertions(+), 4 deletions(-)


Redefine usage of pthread_cleanup_push and _pop, to explicitly call free for
heap objects in error paths.

By the way, set a suitable errno value for an error path that had none.

This is V2 after comments from Ian Campbell.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>

diff -r 588d0dc298a4 -r a83fd69dcb27 tools/xenstore/xs.c
--- a/tools/xenstore/xs.c
+++ b/tools/xenstore/xs.c
@@ -110,6 +110,11 @@ struct xs_handle {
 
 #define read_thread_exists(h)	(h->read_thr_exists)
 
+/* Because pthread_cleanup_p* are not available when USE_PTHREAD is
+ * disabled, use these macros which convert appropriately. */
+#define cleanup_push_heap(p)        cleanup_push(free, p)
+#define cleanup_pop_heap(run, p)    cleanup_pop((run))
+
 static void *read_thread(void *arg);
 
 #else /* !defined(USE_PTHREAD) */
@@ -130,6 +135,9 @@ struct xs_handle {
 #define cleanup_pop(run)	((void)0)
 #define read_thread_exists(h)	(0)
 
+#define cleanup_push_heap(p)        ((void)0)
+#define cleanup_pop_heap(run, p)    do { if ((run)) free(p); } while(0)
+
 #endif
 
 static int read_message(struct xs_handle *h, int nonblocking);
@@ -1059,7 +1067,7 @@ static int read_message(struct xs_handle
 	msg = malloc(sizeof(*msg));
 	if (msg == NULL)
 		goto error;
-	cleanup_push(free, msg);
+	cleanup_push_heap(msg);
 	if (!read_all(h->fd, &msg->hdr, sizeof(msg->hdr), nonblocking)) { /* Cancellation point */
 		saved_errno = errno;
 		goto error_freemsg;
@@ -1069,7 +1077,7 @@ static int read_message(struct xs_handle
 	body = msg->body = malloc(msg->hdr.len + 1);
 	if (body == NULL)
 		goto error_freemsg;
-	cleanup_push(free, body);
+	cleanup_push_heap(body);
 	if (!read_all(h->fd, body, msg->hdr.len, 0)) { /* Cancellation point */
 		saved_errno = errno;
 		goto error_freebody;
@@ -1098,6 +1106,7 @@ static int read_message(struct xs_handle
 		/* There should only ever be one response pending! */
 		if (!list_empty(&h->reply_list)) {
 			mutex_unlock(&h->reply_mutex);
+			saved_errno = EEXIST; 
 			goto error_freebody;
 		}
 
@@ -1110,9 +1119,9 @@ static int read_message(struct xs_handle
 	ret = 0;
 
 error_freebody:
-	cleanup_pop(ret == -1);
+	cleanup_pop_heap(ret == -1, body);
 error_freemsg:
-	cleanup_pop(ret == -1);
+	cleanup_pop_heap(ret == -1, msg);
 error:
 	errno = saved_errno;