1// Copyright (c) 2011 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// Define the necessary code and global data to look for kDebugOnStart command 6// line argument. When the command line argument is detected, it invokes the 7// debugger, if no system-wide debugger is registered, a debug break is done. 8 9#ifndef BASE_DEBUG_DEBUG_ON_START_WIN_H_ 10#define BASE_DEBUG_DEBUG_ON_START_WIN_H_ 11#pragma once 12 13#include "base/basictypes.h" 14#include "build/build_config.h" 15 16// This only works on Windows. It's legal to include on other platforms, but 17// will be a NOP. 18#if defined(OS_WIN) 19 20#ifndef DECLSPEC_SELECTANY 21#define DECLSPEC_SELECTANY __declspec(selectany) 22#endif 23 24namespace base { 25namespace debug { 26 27// There is no way for this code, as currently implemented, to work across DLLs. 28// TODO(rvargas): It looks like we really don't use this code, at least not for 29// Chrome. Figure out if it's really worth implementing something simpler. 30#if !defined(BASE_DLL) 31 32// Debug on start functions and data. 33class DebugOnStart { 34 public: 35 // Expected function type in the .CRT$XI* section. 36 // Note: See VC\crt\src\internal.h for reference. 37 typedef int (__cdecl *PIFV)(void); 38 39 // Looks at the command line for kDebugOnStart argument. If found, it invokes 40 // the debugger, if this fails, it crashes. 41 static int __cdecl Init(); 42 43 // Returns true if the 'argument' is present in the 'command_line'. It does 44 // not use the CRT, only Kernel32 functions. 45 static bool FindArgument(wchar_t* command_line, const char* argument); 46}; 47 48// Set the function pointer to our function to look for a crash on start. The 49// XIB section is started pretty early in the program initialization so in 50// theory it should be called before any user created global variable 51// initialization code and CRT initialization code. 52// Note: See VC\crt\src\defsects.inc and VC\crt\src\crt0.c for reference. 53#ifdef _WIN64 54 55// "Fix" the segment. On x64, the .CRT segment is merged into the .rdata segment 56// so it contains const data only. 57#pragma const_seg(push, ".CRT$XIB") 58// Declare the pointer so the CRT will find it. 59extern const DebugOnStart::PIFV debug_on_start; 60DECLSPEC_SELECTANY const DebugOnStart::PIFV debug_on_start = 61 &DebugOnStart::Init; 62// Fix back the segment. 63#pragma const_seg(pop) 64 65#else // _WIN64 66 67// "Fix" the segment. On x86, the .CRT segment is merged into the .data segment 68// so it contains non-const data only. 69#pragma data_seg(push, ".CRT$XIB") 70// Declare the pointer so the CRT will find it. 71DECLSPEC_SELECTANY DebugOnStart::PIFV debug_on_start = &DebugOnStart::Init; 72// Fix back the segment. 73#pragma data_seg(pop) 74 75#endif // _WIN64 76 77#endif // defined(BASE_DLL) 78 79} // namespace debug 80} // namespace base 81 82#endif // defined(OS_WIN) 83 84#endif // BASE_DEBUG_DEBUG_ON_START_WIN_H_ 85