From d005e0b4838d86722cd911ba77609b75bace52bb Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Sat, 2 Feb 2019 11:00:26 +0100
Subject: [PATCH] - changed the place where the CheckRequireMouse event gets
 called.

The original place in I_CheckNativeMouse is unsafe because that function can get called from the system message queue which can result in a bad global state of the VM for such a call because it can be recursively invoked from code that may temporarily alter some settings.
---
 src/win32/i_input.cpp | 10 +++++++---
 src/win32/i_input.h   |  2 +-
 src/win32/i_mouse.cpp |  4 ++--
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/win32/i_input.cpp b/src/win32/i_input.cpp
index a2c96ec47..901e61483 100644
--- a/src/win32/i_input.cpp
+++ b/src/win32/i_input.cpp
@@ -150,6 +150,9 @@ extern bool AppActive;
 int SessionState = 0;
 int BlockMouseMove; 
 
+static bool EventHandlerResultForNativeMouse;
+
+
 CVAR (Bool, i_soundinbackground, false, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 CVAR (Bool, k_allowfullscreentoggle, true, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 
@@ -457,11 +460,11 @@ LRESULT CALLBACK WndProc (HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 		return 0;
 
 	case WM_KILLFOCUS:
-		I_CheckNativeMouse (true);	// Make sure mouse gets released right away
+		I_CheckNativeMouse (true, false);	// Make sure mouse gets released right away
 		break;
 
 	case WM_SETFOCUS:
-		I_CheckNativeMouse (false);
+		I_CheckNativeMouse (false, EventHandlerResultForNativeMouse);	// This cannot call the event handler. Doing it from here is unsafe.
 		break;
 
 	case WM_SETCURSOR:
@@ -778,7 +781,8 @@ void I_StartTic ()
 	BlockMouseMove--;
 	ResetButtonTriggers ();
 	I_CheckGUICapture ();
-	I_CheckNativeMouse (false);
+	EventHandlerResultForNativeMouse = eventManager.CheckRequireMouse();
+	I_CheckNativeMouse (false, EventHandlerResultForNativeMouse);
 	I_GetEvent ();
 }
 
diff --git a/src/win32/i_input.h b/src/win32/i_input.h
index 529ea83f5..00f853e9b 100644
--- a/src/win32/i_input.h
+++ b/src/win32/i_input.h
@@ -129,7 +129,7 @@ public:
 extern FJoystickCollection *JoyDevices[NUM_JOYDEVICES];
 
 void I_StartupMouse();
-void I_CheckNativeMouse(bool prefer_native);
+void I_CheckNativeMouse(bool prefer_native, bool eh);
 void I_StartupKeyboard();
 void I_StartupXInput();
 void I_StartupDirectInputJoystick();
diff --git a/src/win32/i_mouse.cpp b/src/win32/i_mouse.cpp
index baa3106b6..9915479b7 100644
--- a/src/win32/i_mouse.cpp
+++ b/src/win32/i_mouse.cpp
@@ -284,7 +284,7 @@ static bool CaptureMode_InGame()
 //
 //==========================================================================
 
-void I_CheckNativeMouse(bool preferNative)
+void I_CheckNativeMouse(bool preferNative, bool eventhandlerresult)
 {
 	bool windowed = (screen == NULL) || !screen->IsFullscreen();
 	bool want_native;
@@ -311,7 +311,7 @@ void I_CheckNativeMouse(bool preferNative)
 		}
 	}
 
-	if (!want_native && eventManager.CheckRequireMouse())
+	if (!want_native && eventhandlerresult)
 		want_native = true;
 
 	//Printf ("%d %d %d\n", wantNative, preferNative, NativeMouse);