Win32: Fix using executable instance and not ours

Operations that take an instance handle should be passed the handle of
whatever module we are inside instead of blindly passing the handle of
the executable.

This commit makes GLFW retrieve its own instance on initialization.

This makes the most difference for window classes, which are
per-instance.  Using the executable instance led to name conflicts if
there were several copies of GLFW in a single process.

Note that having this is still a bad idea unless you know what things to
avoid, and those things are mostly platform-specific.  This is partly
because the library wasn't designed for it and partly because it needs
to save, update and restore various per-process and per-session settings
like current context and video mode.

However, multiple simultaneous copies of GLFW in a single Win32 process
should now at least initialize, like is already the case on other
platforms.

Fixes #469
Fixes #1296
Fixes #1395
Related to #927
Related to #1885

(cherry picked from commit 07a5518c3e)

CONTRIBUTORS.md

@@ -89,6 +89,7 @@ video tutorials.
  - IntellectualKitty
  - Aaron Jacobs
  - Erik S. V. Jansson
+ - jjYBdx4IL
  - Toni Jovanoski
  - Arseny Kapoulkine
  - Cem Karan
@@ -203,6 +204,7 @@ video tutorials.
  - TTK-Bandit
  - Sergey Tikhomirov
  - Arthur Tombs
+ - TronicLabs
  - Ioannis Tsakpinis
  - Samuli Tuomola
  - Matthew Turner

README.md

@@ -127,6 +127,7 @@ information on what to include when reporting a bug.
    scancode than `PrtSc` (#1993)
  - [Win32] Bugfix: `GLFW_KEY_PAUSE` scancode from `glfwGetKeyScancode` did not
    match event scancode (#1993)
+ - [Win32] Bugfix: Instance-local operations used executable instance (#469,#1296,#1395)
 
 
 ## Contact

src/win32_init.c

@@ -72,6 +72,16 @@ BOOL WINAPI DllMain(HINSTANCE instance, DWORD reason, LPVOID reserved)
 //
 static GLFWbool loadLibraries(void)
 {
+    if (!GetModuleHandleExW(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
+                                GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
+                            (const WCHAR*) &_glfw,
+                            (HMODULE*) &_glfw.win32.instance))
+    {
+        _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
+                             "Win32: Failed to retrieve own module handle");
+        return GLFW_FALSE;
+    }
+
     _glfw.win32.user32.instance = LoadLibraryA("user32.dll");
     if (!_glfw.win32.user32.instance)
     {
@@ -335,7 +345,7 @@ static GLFWbool createHelperWindow(void)
                         WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
                         0, 0, 1, 1,
                         NULL, NULL,
-                        GetModuleHandleW(NULL),
+                        _glfw.win32.instance,
                         NULL);
 
     if (!_glfw.win32.helperWindowHandle)

src/win32_joystick.c

@@ -497,7 +497,7 @@ void _glfwInitJoysticksWin32(void)
 {
     if (_glfw.win32.dinput8.instance)
     {
-        if (FAILED(DirectInput8Create(GetModuleHandleW(NULL),
+        if (FAILED(DirectInput8Create(_glfw.win32.instance,
                                       DIRECTINPUT_VERSION,
                                       &IID_IDirectInput8W,
                                       (void**) &_glfw.win32.dinput8.api,

src/win32_platform.h

@@ -334,6 +334,7 @@ typedef struct _GLFWwindowWin32
 //
 typedef struct _GLFWlibraryWin32
 {
+    HINSTANCE           instance;
     HWND                helperWindowHandle;
     HDEVNOTIFY          deviceNotificationHandle;
     DWORD               foregroundLockTimeout;

src/win32_window.c

@@ -1317,7 +1317,7 @@ static int createNativeWindow(_GLFWwindow* window,
                                            fullWidth, fullHeight,
                                            NULL, // No parent window
                                            NULL, // No window menu
-                                           GetModuleHandleW(NULL),
+                                           _glfw.win32.instance,
                                            (LPVOID) wndconfig);
 
     free(wideTitle);
@@ -1429,7 +1429,7 @@ GLFWbool _glfwRegisterWindowClassWin32(void)
     wc.cbSize        = sizeof(wc);
     wc.style         = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
     wc.lpfnWndProc   = (WNDPROC) windowProc;
-    wc.hInstance     = GetModuleHandleW(NULL);
+    wc.hInstance     = _glfw.win32.instance;
     wc.hCursor       = LoadCursorW(NULL, IDC_ARROW);
     wc.lpszClassName = _GLFW_WNDCLASSNAME;
 
@@ -1459,7 +1459,7 @@ GLFWbool _glfwRegisterWindowClassWin32(void)
 //
 void _glfwUnregisterWindowClassWin32(void)
 {
-    UnregisterClassW(_GLFW_WNDCLASSNAME, GetModuleHandleW(NULL));
+    UnregisterClassW(_GLFW_WNDCLASSNAME, _glfw.win32.instance);
 }
 
 
@@ -2348,7 +2348,7 @@ VkResult _glfwPlatformCreateWindowSurface(VkInstance instance,
 
     memset(&sci, 0, sizeof(sci));
     sci.sType = VK_STRUCTURE_TYPE_WIN32_SURFACE_CREATE_INFO_KHR;
-    sci.hinstance = GetModuleHandleW(NULL);
+    sci.hinstance = _glfw.win32.instance;
     sci.hwnd = window->win32.handle;
 
     err = vkCreateWin32SurfaceKHR(instance, &sci, allocator, surface);