Handle SIGBREAK (Windows console close) (#2473)

SetConsoleCtrlHandler is not needed because SIGBREAK is also sent
on window close. The process is killed when the thread handling
SIGBREAK returns. That's why we must handle it synchronously
and wait for other threads to finish first. The Windows-defined
timeout is only 5 seconds but there is no way to change that.

https://docs.microsoft.com/en-us/windows/console/ctrl-c-and-ctrl-break-signals

Fixes #1277
Fixes #1853

src/signals.cpp

@@ -35,8 +35,12 @@
 #include "globalevent.h"
 #include "monster.h"
 #include "events.h"
+#include "scheduler.h"
+#include "databasetasks.h"
 
 
+extern Scheduler g_scheduler;
+extern DatabaseTasks g_databaseTasks;
 extern Dispatcher g_dispatcher;
 
 extern ConfigManager g_config;
@@ -63,6 +67,11 @@ Signals::Signals(boost::asio::io_service& service) :
 #ifndef _WIN32
 	set.add(SIGUSR1);
 	set.add(SIGHUP);
+#else
+	// This must be a blocking call as Windows calls it in a new thread and terminates
+	// the process when the handler returns (or after 5 seconds, whichever is earlier).
+	// On Windows it is called in a new thread.
+	signal(SIGBREAK, dispatchSignalHandler);
 #endif
 
 	asyncWait();
@@ -80,6 +89,9 @@ void Signals::asyncWait()
 	});
 }
 
+// On Windows this function does not need to be signal-safe,
+// as it is called in a new thread.
+// https://github.com/otland/forgottenserver/pull/2473
 void Signals::dispatchSignalHandler(int signal)
 {
 	switch(signal) {
@@ -96,12 +108,27 @@ void Signals::dispatchSignalHandler(int signal)
 		case SIGUSR1: //Saves game state
 			g_dispatcher.addTask(createTask(sigusr1Handler));
 			break;
+#else
+		case SIGBREAK: //Shuts the server down
+			g_dispatcher.addTask(createTask(sigbreakHandler));
+			// hold the thread until other threads end
+			g_scheduler.join();
+			g_databaseTasks.join();
+			g_dispatcher.join();
+			break;
 #endif
 		default:
 			break;
 	}
 }
 
+void Signals::sigbreakHandler()
+{
+	//Dispatcher thread
+	std::cout << "SIGBREAK received, shutting game server down..." << std::endl;
+	g_game.setGameState(GAME_STATE_SHUTDOWN);
+}
+
 void Signals::sigtermHandler()
 {
 	//Dispatcher thread

src/signals.h

@@ -32,6 +32,7 @@ class Signals
 		void asyncWait();
 		static void dispatchSignalHandler(int signal);
 
+		static void sigbreakHandler();
 		static void sigintHandler();
 		static void sighupHandler();
 		static void sigtermHandler();