action.sa_handler = handle_tick;
sigemptyset(&action.sa_mask);
+
+#ifdef SA_RESTART
+ // specify SA_RESTART. One consequence if we don't do this is
+ // that readline gets confused by the -threaded RTS. It seems
+ // that if a SIGALRM handler is installed without SA_RESTART,
+ // readline installs its own SIGALRM signal handler (see
+ // readline's signals.c), and this somehow causes readline to go
+ // wrong when the input exceeds a single line (try it).
+ action.sa_flags = SA_RESTART;
+#else
action.sa_flags = 0;
+#endif
return sigaction(ITIMER_SIGNAL, &action, NULL);
}