dbus: honor the shutdown timeout in the reboot family

initctl -t N reboot arms an emergency bypass timer over the legacy
socket, but the bus methods took no argument, so the timeout was
silently dropped whenever D-Bus was up.

Reboot, Halt, and Poweroff now take a timeout in seconds, 0 for
none, armed via the same shutdown_bypass() the legacy path uses.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/sm.c

@@ -94,6 +94,29 @@ static void shutdown_wdt_cb(uev_t *w, void *arg, int events)
 	do_shutdown(halt);
 }
 
+/*
+ * Emergency shutdown bypass, same job as the shutdown watchdog above
+ * but armed by the user: `initctl -t SEC reboot`, on either transport.
+ */
+static void bypass_shutdown(void *unused)
+{
+	(void)unused;
+
+	cprintf("TIMEOUT TIMEOUT SHUTTING DOWN NOW!!\n");
+	do_shutdown(halt);
+}
+
+static struct wq emergency = { .cb = bypass_shutdown };
+
+void shutdown_bypass(int timeout)
+{
+	if (timeout <= 0)
+		return;
+
+	emergency.delay = timeout * 1000;
+	schedule_work(&emergency);
+}
+
 /*
  * User-requested runlevel change, shared by the legacy API and the
  * D-Bus SetRunlevel method.  Refused in runlevel 0/6, deferred via