start: switch from SOCK_DGRAM to SOCK_STREAM

Writes < PIPE_BUF will be atomic. PIPE_BUF is guaranteed to be 512 by POSIX and
Linux guarantess 4096. Nothing we send around goes over this limit.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

src/lxc/start.c

@@ -1150,7 +1150,7 @@ static int lxc_spawn(struct lxc_handler *handler)
 	if (lxc_sync_init(handler))
 		return -1;
 
-	ret = socketpair(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0,
+	ret = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0,
 			 handler->data_sock);
 	if (ret < 0) {
 		lxc_sync_fini(handler);