Codechange: [Emscripten] Improve syncfs synchronisation on exit/abort

os/emscripten/pre.js

@@ -52,24 +52,26 @@ Module.preRun.push(function() {
     });
 
     window.openttd_syncfs_shown_warning = false;
-    window.openttd_syncfs = function() {
+    window.openttd_syncfs = function(callback) {
         /* Copy the virtual FS to the persistent storage. */
-        FS.syncfs(false, function (err) { });
+        FS.syncfs(false, function (err) {
+            /* On first time, warn the user about the volatile behaviour of
+             * persistent storage. */
+            if (!window.openttd_syncfs_shown_warning) {
+                window.openttd_syncfs_shown_warning = true;
+                Module.onWarningFs();
+            }
 
-        /* On first time, warn the user about the volatile behaviour of
+            if (callback) callback();
-         * persistent storage. */
+        });
-        if (!window.openttd_syncfs_shown_warning) {
-            window.openttd_syncfs_shown_warning = true;
-            Module.onWarningFs();
-        }
     }
 
     window.openttd_exit = function() {
-        Module.onExit();
+        window.openttd_syncfs(Module.onExit);
     }
 
     window.openttd_abort = function() {
-        Module.onAbort();
+        window.openttd_syncfs(Module.onAbort);
     }
 
     window.openttd_server_list = function() {

src/openttd.cpp

@@ -118,7 +118,6 @@ void UserErrorI(const std::string &str)
 	/* In effect, the game ends here. As emscripten_set_main_loop() caused
 	 * the stack to be unwound, the code after MainLoop() in
 	 * openttd_main() is never executed. */
-	EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
 	EM_ASM(if (window["openttd_abort"]) openttd_abort());
 #endif
 

src/video/sdl2_v.cpp

@@ -615,7 +615,6 @@ void VideoDriver_SDL_Base::LoopOnce()
 		/* In effect, the game ends here. As emscripten_set_main_loop() caused
 		 * the stack to be unwound, the code after MainLoop() in
 		 * openttd_main() is never executed. */
-		EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
 		EM_ASM(if (window["openttd_exit"]) openttd_exit());
 #endif
 		return;