[Windows Sandbox] MITIGATION_EXTENSION_POINT_DISABLE support for children.

sandbox/win/tests/integration_tests/hooking_win_proc.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "integration_tests_common.h"
+
+#include <windows.h>
+
+LRESULT CALLBACK WndProc(HWND window,
+                         UINT message,
+                         WPARAM w_param,
+                         LPARAM l_param) {
+  // Injected keystroke via PostThreadMessage won't be dispatched to here.
+  // Have to use SendMessage or SendInput to trigger the keyboard hook.
+  switch (message) {
+    case WM_KEYDOWN:
+      break;
+    case WM_KEYUP:
+      break;
+    case WM_CLOSE:
+      ::DestroyWindow(window);
+      break;
+    case WM_DESTROY:
+      ::PostQuitMessage(0);
+      break;
+    default:
+      return ::DefWindowProc(window, message, w_param, l_param);
+  }
+  return 0;
+}
+
+int WINAPI WinMain(HINSTANCE instance,
+                   HINSTANCE prev_instance,
+                   LPSTR cmd_line,
+                   int cmd_show) {
+  // The parent process should have set up this named event already.
+  HANDLE event = ::OpenEventW(EVENT_MODIFY_STATE, FALSE, g_winproc_event);
+  if (event == NULL || event == INVALID_HANDLE_VALUE)
+    return 1;
+
+  // Step 1: Registering the Window Class.
+  WNDCLASSEX window_class;
+  window_class.cbSize = sizeof(WNDCLASSEX);
+  window_class.style = 0;
+  window_class.lpfnWndProc = WndProc;
+  window_class.cbClsExtra = 0;
+  window_class.cbWndExtra = 0;
+  window_class.hInstance = instance;
+  window_class.hIcon = ::LoadIcon(NULL, IDI_APPLICATION);
+  window_class.hCursor = ::LoadCursor(NULL, IDC_ARROW);
+  window_class.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);

[Will Harris, 2016/05/18 09:02:29]

nit: c++ cast (e.g. static_cast<>) - is it even needed?

also, can you use COLOR_WINDOWFRAME instead of COLOR_WINDOW + 1?

[penny, 2016/06/14 21:45:09]

Yes, the cast is needed, otherwise "int" can't be assigned to type HBRUSH.

But I've fixed it to actually be reinterpret_cast<>.  Static_cast<> doesn't work
here because HBRUSH is actually defined as "typedef HBRUSH__ *HBRUSH".

...and I made it COLOR_WINDOWFRAME.

+  window_class.lpszMenuName = NULL;
+  window_class.lpszClassName = g_winproc_class_name;
+  window_class.hIconSm = ::LoadIcon(NULL, IDI_APPLICATION);
+
+  if (!::RegisterClassEx(&window_class))
+    return 1;
+
+  // Step 2: Create the Window.
+  HWND window = ::CreateWindowExW(WS_EX_CLIENTEDGE, g_winproc_class_name,
+                                  g_winproc_window_name, WS_OVERLAPPEDWINDOW,
+                                  CW_USEDEFAULT, CW_USEDEFAULT, 240, 120, NULL,
+                                  NULL, instance, NULL);
+
+  if (window == NULL)
+    return 1;
+
+  ::ShowWindow(window, cmd_show);
+  ::UpdateWindow(window);
+
+  // Step 3: Signal that WinProc is up and running.
+  ::SetEvent(event);
+
+  // Step 4: The Message Loop
+  // WM_QUIT results in a 0 value from GetMessageW,
+  // breaking the loop.
+  MSG message;
+  while (::GetMessageW(&message, NULL, 0, 0) > 0) {
+    ::TranslateMessage(&message);
+    ::DispatchMessageW(&message);
+  }
+
+  ::SetEvent(event);
+  ::CloseHandle(event);
+
+  return message.wParam;
+}