michael@0: // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: // Define the necessary code and global data to look for kDebugOnStart command
michael@0: // line argument. When the command line argument is detected, it invokes the
michael@0: // debugger, if no system-wide debugger is registered, a debug break is done.
michael@0: 
michael@0: #ifndef BASE_DEBUG_ON_START_H_
michael@0: #define BASE_DEBUG_ON_START_H_
michael@0: 
michael@0: #include "base/basictypes.h"
michael@0: 
michael@0: // This only works on MSVC.
michael@0: #if defined(COMPILER_MSVC)
michael@0: 
michael@0: #ifndef DECLSPEC_SELECTANY
michael@0: #define DECLSPEC_SELECTANY  __declspec(selectany)
michael@0: #endif
michael@0: 
michael@0: // Debug on start functions and data.
michael@0: class DebugOnStart {
michael@0:  public:
michael@0:   // Expected function type in the .CRT$XI* section.
michael@0:   // Note: See VC\crt\src\internal.h for reference.
michael@0:   typedef int  (__cdecl *PIFV)(void);
michael@0: 
michael@0:   // Looks at the command line for kDebugOnStart argument. If found, it invokes
michael@0:   // the debugger, if this fails, it crashes.
michael@0:   static int __cdecl Init();
michael@0: 
michael@0:   // Returns true if the 'argument' is present in the 'command_line'. It does
michael@0:   // not use the CRT, only Kernel32 functions.
michael@0:   static bool FindArgument(wchar_t* command_line, const wchar_t* argument);
michael@0: };
michael@0: 
michael@0: // Set the function pointer to our function to look for a crash on start. The
michael@0: // XIB section is started pretty early in the program initialization so in
michael@0: // theory it should be called before any user created global variable
michael@0: // initialization code and CRT initialization code.
michael@0: // Note: See VC\crt\src\defsects.inc and VC\crt\src\crt0.c for reference.
michael@0: #ifdef _WIN64
michael@0: 
michael@0: // "Fix" the segment. On x64, the .CRT segment is merged into the .rdata segment
michael@0: // so it contains const data only.
michael@0: #pragma const_seg(push, ".CRT$XIB")
michael@0: // Declare the pointer so the CRT will find it.
michael@0: extern const DebugOnStart::PIFV debug_on_start;
michael@0: DECLSPEC_SELECTANY const DebugOnStart::PIFV debug_on_start =
michael@0:     &DebugOnStart::Init;
michael@0: // Fix back the segment.
michael@0: #pragma const_seg(pop)
michael@0: 
michael@0: #else  // _WIN64
michael@0: 
michael@0: // "Fix" the segment. On x86, the .CRT segment is merged into the .data segment
michael@0: // so it contains non-const data only.
michael@0: #pragma data_seg(push, ".CRT$XIB")
michael@0: // Declare the pointer so the CRT will find it.
michael@0: DECLSPEC_SELECTANY DebugOnStart::PIFV debug_on_start = &DebugOnStart::Init;
michael@0: // Fix back the segment.
michael@0: #pragma data_seg(pop)
michael@0: 
michael@0: #endif  // _WIN64
michael@0: #endif  // defined(OS_WIN)
michael@0: 
michael@0: #endif  // BASE_DEBUG_ON_START_H_