1// Copyright (c) 2010 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// Main entry point for a DLL that can be instructed to crash on
6// load or unload by setting an environment variable appropriately.
7//
8// Note: This code has no CRT to lean on, because some versions of the CRT
9//    have a bug whereby they leave dangling state after taking an exception
10//    during DLL_PROCESS_ATTACH. This in turn causes the loading process to
11//    crash on exit. To work around this, this DLL has its entrypoint set
12//    to the DllMain routine and does not link with the CRT.
13
14#include <windows.h>
15
16#include "crash_dll.h"
17
18void Crash() {
19  char* null_pointer = reinterpret_cast<char*>(kCrashAddress);
20
21  *null_pointer = '\0';
22}
23
24void CrashConditionally(const wchar_t* name) {
25  wchar_t value[1024];
26  DWORD ret = ::GetEnvironmentVariable(name, value, ARRAYSIZE(value));
27  if (ret != 0 || ERROR_ENVVAR_NOT_FOUND != ::GetLastError())
28    Crash();
29}
30
31extern "C" BOOL WINAPI DllMain(HINSTANCE instance, DWORD reason,
32                               LPVOID reserved) {
33  if (reason == DLL_PROCESS_ATTACH)
34    CrashConditionally(kCrashOnLoadMode);
35  else if (reason == DLL_PROCESS_DETACH)
36    CrashConditionally(kCrashOnUnloadMode);
37
38  return 1;
39}
40