res_alarmsystem: Suspend client thread until PBX fully booted.

Wait until Asterisk has finished starting fully before letting
the client threads do anything useful. This ensures events
which can trigger user dialplan callbacks don't fire before
the PBX is fully booted, since dialplan can't be executed
while Asterisk is still starting.

res/res_alarmsystem.c

@@ -1648,6 +1648,13 @@ static void *client_thread(void *arg)
 		numfds++;
 	}
 
+	/* Wait until the PBX is fully booted, similar to "core waitfullybooted"
+	 * This is necessary because dialplan won't execute while the PBX is still booting,
+	 * and events, including EVENT_ALARM_OKAY, can trigger user callbacks which execute dialplan. */
+	while (!ast_test_flag(&ast_options, AST_OPT_FLAG_FULLY_BOOTED)) {
+		usleep(1000);
+	}
+
 	/* First send a ping to initialize UDP communication and see if the network is up.
 	 * This will generate the event but not actually process it until we start
 	 * executing the loop, at which time we'll service the alertpipe immediately. */