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. 22 class 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. 48 extern const DebugOnStart::PIFV debug_on_start; 49 DECLSPEC_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. 60 DECLSPEC_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
