cleanup: dmeventd improve _clien_write code

Switch to allocate buffer from heap, since it might be potentially
bigger when extremaly large set of volumes would be monitored.
In case of allocation failure send ENOMEM message.
Also implicitelly ignore msg->size when msg->data is NULL.

1 files changed, 19 insertions, 7 deletions

diff --git a/daemons/dmeventd/dmeventd.c b/daemons/dmeventd/dmeventd.c
index f8b547019..b4080db9f 100644
--- a/daemons/dmeventd/dmeventd.c
+++ b/daemons/dmeventd/dmeventd.c
@@ -1397,18 +1397,27 @@ static int _client_read(struct dm_event_fifos *fifos,
 static int _client_write(struct dm_event_fifos *fifos,
 			struct dm_event_daemon_message *msg)
 {
+	uint32_t temp[2];
 	unsigned bytes = 0;
 	int ret = 0;
 	fd_set fds;
 
-	size_t size = 2 * sizeof(uint32_t) + msg->size;
-	uint32_t *header = alloca(size);
+	size_t size = 2 * sizeof(uint32_t) + ((msg->data) ? msg->size : 0);
+	uint32_t *header = dm_malloc(size);
 	char *buf = (char *)header;
 
-	header[0] = htonl(msg->cmd);
-	header[1] = htonl(msg->size);
-	if (msg->data)
-		memcpy(buf + 2 * sizeof(uint32_t), msg->data, msg->size);
+	if (!header) {
+		/* Reply with ENOMEM message */
+		header = temp;
+		size = sizeof(temp);
+		header[0] = htonl(-ENOMEM);
+		header[1] = 0;
+	} else {
+		header[0] = htonl(msg->cmd);
+		header[1] = htonl((msg->data) ? msg->size : 0);
+		if (msg->data)
+			memcpy(buf + 2 * sizeof(uint32_t), msg->data, msg->size);
+	}
 
 	while (bytes < size) {
 		do {
@@ -1423,7 +1432,10 @@ static int _client_write(struct dm_event_fifos *fifos,
 			break;
 	}
 
-	return bytes == size;
+	if (header != temp)
+		dm_free(header);
+
+	return (bytes == size);
 }
 
 /*