check malloc failure

luad.c

@@ -216,6 +216,9 @@ int main(int argc, char **argv)
                 int len = recvmsg(socket, &msg , 0);
                 int *peer_fds = fds_from_msg(&msg, 5);
                 char *argline = malloc(len);
+                if(! argline) {
+                    die("malloc failed");
+                }
                 memmove(argline, buf, len);
 
                 pid_t child_pid = fork_lua(L, argline, len, peer_fds, 5);