chrome/app/delay_load_hook_win.cc

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/app/delay_load_hook_win.h"
   6
   7 #include <DelayIMP.h>
   8
   9 #include "base/logging.h"
  10 #include "base/strings/string_util.h"
  11 #include "base/strings/stringprintf.h"
  12
  13 // So long as these symbols are supplied to the final binary through an
  14 // object file (as opposed to indirectly through a library), these pointers
  15 // will override the CRT's symbols and direct the notifications to our hook.
  16 // Alternatively referencing the ChromeDelayLoadHook function somehow will
  17 // cause this declaration of these variables to take preference to the delay
  18 // load runtime's defaults (in delayimp.lib).
  19 PfnDliHook __pfnDliNotifyHook2 = ChromeDelayLoadHook;
  20 PfnDliHook __pfnDliFailureHook2 = ChromeDelayLoadHook;
  21
  22
  23 namespace {
  24
  25 FARPROC OnPreLoadLibrary(DelayLoadInfo* info) {
  26   // If the DLL name ends with "-delay.dll", this call is about one of our
  27   // custom import libraries. In this case we need to snip the suffix off,
  28   // and bind to the real DLL.
  29   std::string dll_name(info->szDll);
  30   const char kDelaySuffix[] = "-delay.dll";
  31   if (EndsWith(dll_name, kDelaySuffix, false)) {
  32     // Trim the "-delay.dll" suffix from the string.
  33     dll_name.resize(dll_name.length() - (sizeof(kDelaySuffix) - 1));
  34     dll_name.append(".dll");
  35
  36     return reinterpret_cast<FARPROC>(::LoadLibraryA(dll_name.c_str()));
  37   }
  38
  39   return NULL;
  40 }
  41
  42 }  // namespace
  43
  44 // This function is a delay load notification hook. It is invoked by the
  45 // delay load support in the visual studio runtime.
  46 // See http://msdn.microsoft.com/en-us/library/z9h1h6ty(v=vs.100).aspx for
  47 // details.
  48 extern "C" FARPROC WINAPI ChromeDelayLoadHook(unsigned reason,
  49                                               DelayLoadInfo* info) {
  50   switch (reason) {
  51     case dliNoteStartProcessing:
  52     case dliNoteEndProcessing:
  53       // Nothing to do here.
  54       break;
  55
  56     case dliNotePreLoadLibrary:
  57       return OnPreLoadLibrary(info);
  58       break;
  59
  60     case dliNotePreGetProcAddress:
  61       // Nothing to do here.
  62       break;
  63
  64     case dliFailLoadLib:
  65     case dliFailGetProc:
  66       // Returning NULL from error notifications will cause the delay load
  67       // runtime to raise a VcppException structured exception, that some code
  68       // might want to handle.
  69       return NULL;
  70       break;
  71
  72     default:
  73       NOTREACHED() << "Impossible delay load notification.";
  74       break;
  75   }
  76
  77   // Returning NULL causes the delay load machinery to perform default
  78   // processing for this notification.
  79   return NULL;
  80 }