1// Copyright (c) 2006-2008 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_ON_START_H_ 10#define BASE_DEBUG_ON_START_H_ 11 12#include "base/basictypes.h" 13 14// This only works on Windows. 15#if defined(OS_WIN) 16 17#ifndef DECLSPEC_SELECTANY 18#define DECLSPEC_SELECTANY __declspec(selectany) 19#endif 20 21// Debug on start functions and data. 22class DebugOnStart { 23 public: 24 // Expected function type in the .CRT$XI* section. 25 // Note: See VC\crt\src\internal.h for reference. 26 typedef int (__cdecl *PIFV)(void); 27 28 // Looks at the command line for kDebugOnStart argument. If found, it invokes 29 // the debugger, if this fails, it crashes. 30 static int __cdecl Init(); 31 32 // Returns true if the 'argument' is present in the 'command_line'. It does 33 // not use the CRT, only Kernel32 functions. 34 static bool FindArgument(wchar_t* command_line, const char* argument); 35}; 36 37// Set the function pointer to our function to look for a crash on start. The 38// XIB section is started pretty early in the program initialization so in 39// theory it should be called before any user created global variable 40// initialization code and CRT initialization code. 41// Note: See VC\crt\src\defsects.inc and VC\crt\src\crt0.c for reference. 42#ifdef _WIN64 43 44// "Fix" the segment. On x64, the .CRT segment is merged into the .rdata segment 45// so it contains const data only. 46#pragma const_seg(push, ".CRT$XIB") 47// Declare the pointer so the CRT will find it. 48extern const DebugOnStart::PIFV debug_on_start; 49DECLSPEC_SELECTANY const DebugOnStart::PIFV debug_on_start = 50 &DebugOnStart::Init; 51// Fix back the segment. 52#pragma const_seg(pop) 53 54#else // _WIN64 55 56// "Fix" the segment. On x86, the .CRT segment is merged into the .data segment 57// so it contains non-const data only. 58#pragma data_seg(push, ".CRT$XIB") 59// Declare the pointer so the CRT will find it. 60DECLSPEC_SELECTANY DebugOnStart::PIFV debug_on_start = &DebugOnStart::Init; 61// Fix back the segment. 62#pragma data_seg(pop) 63 64#endif // _WIN64 65#endif // defined(OS_WIN) 66 67#endif // BASE_DEBUG_ON_START_H_ 68