shared source/wpf/src/host/dll/detours.cxx

   1 //+-----------------------------------------------------------------------
   2 //
   3 //  Copyright (c) Microsoft Corporation.  All rights reserved.
   4 //
   5 //  Description:
   6 //      [See .hxx]
   7 //
   8 //------------------------------------------------------------------------
   9
  10 #include "precompiled.hxx"
  11 #include "Detours.hxx"
  12 #include "..\Detours\Detours.h"
  13
  14 // The managed PresentationHostSecurityManager needs to convince the ClickOnce elevation prompt to use the
  15 // browser's top-level window as the owner. The prompt dialog is created without an explicit owner, on its
  16 // own thread. As a fallback, SWF.Form.ShowDialog() uses the active window as owner. But there is no other
  17 // window on the dialog's thread. So, we fake it by detouring ::GetActiveWindow() and returning the browser's
  18 // top-level window on the first call.
  19 HWND g_fakeActiveWindow;
  20
  21 // DLL-exported. Called by PresentationHostSecurityManager.
  22 void __stdcall SetFakeActiveWindow(HWND hwnd)
  23 {
  24     g_fakeActiveWindow = hwnd;
  25 }
  26
  27 HWND (WINAPI *Detours::s_pfGetActiveWindow)() = &GetActiveWindow;
  28
  29 HRESULT Detours::Init()
  30 {
  31     HRESULT hr = S_OK;
  32
  33     CHECK_ERROR_CODE(DetourTransactionBegin());
  34     CHECK_ERROR_CODE(DetourUpdateThread(GetCurrentThread()));
  35     CHECK_ERROR_CODE(DetourAttach((void**)&s_pfGetActiveWindow, GetActiveWindowDetour));
  36     CHECK_ERROR_CODE(DetourTransactionCommit());
  37
  38 Cleanup:
  39     return hr;
  40 }
  41
  42 void Detours::Uninit()
  43 {
  44     if(s_pfGetActiveWindow != GetActiveWindow) // detoured?
  45     {
  46         if(DetourTransactionBegin() == NOERROR &&
  47             DetourUpdateThread(GetCurrentThread()) == NOERROR &&
  48             DetourDetach((void**)&s_pfGetActiveWindow, GetActiveWindowDetour) == NOERROR)
  49         {
  50             DetourTransactionCommit();
  51         }
  52         else
  53         {
  54             ASSERT(false);
  55         }
  56     }
  57 }
  58
  59 HWND Detours::GetActiveWindowDetour()
  60 {
  61     if(g_fakeActiveWindow)
  62     {
  63         HWND hwnd = g_fakeActiveWindow;
  64         g_fakeActiveWindow = 0;
  65         return hwnd;
  66     }
  67     return (*s_pfGetActiveWindow)(); // call the real function
  68 }
  69