base/debug/debug_on_start_win.cc

   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 #include "base/debug/debug_on_start_win.h"
   6
   7 #include <windows.h>
   8
   9 #include "base/base_switches.h"
  10 #include "base/basictypes.h"
  11 #include "base/debug/debugger.h"
  12
  13 namespace base {
  14 namespace debug {
  15
  16 // Minimalist implementation to try to find a command line argument. We can use
  17 // kernel32 exported functions but not the CRT functions because we're too early
  18 // in the process startup.
  19 // The code is not that bright and will find things like ---argument or
  20 // /-/argument.
  21 // Note: command_line is non-destructively modified.
  22 bool DebugOnStart::FindArgument(wchar_t* command_line, const char* argument_c) {
  23   wchar_t argument[50] = {};
  24   for (int i = 0; argument_c[i]; ++i)
  25     argument[i] = argument_c[i];
  26
  27   int argument_len = lstrlen(argument);
  28   int command_line_len = lstrlen(command_line);
  29   while (command_line_len > argument_len) {
  30     wchar_t first_char = command_line[0];
  31     wchar_t last_char = command_line[argument_len+1];
  32     // Try to find an argument.
  33     if ((first_char == L'-' || first_char == L'/') &&
  34         (last_char == L' ' || last_char == 0 || last_char == L'=')) {
  35       command_line[argument_len+1] = 0;
  36       // Skip the - or /
  37       if (lstrcmpi(command_line+1, argument) == 0) {
  38         // Found it.
  39         command_line[argument_len+1] = last_char;
  40         return true;
  41       }
  42       // Fix back.
  43       command_line[argument_len+1] = last_char;
  44     }
  45     // Continue searching.
  46     ++command_line;
  47     --command_line_len;
  48   }
  49   return false;
  50 }
  51
  52 // static
  53 int __cdecl DebugOnStart::Init() {
  54   // Try to find the argument.
  55   if (FindArgument(GetCommandLine(), switches::kDebugOnStart)) {
  56     // We can do 2 things here:
  57     // - Ask for a debugger to attach to us. This involve reading the registry
  58     //   key and creating the process.
  59     // - Do a int3.
  60
  61     // It will fails if we run in a sandbox. That is expected.
  62     base::debug::SpawnDebuggerOnProcess(GetCurrentProcessId());
  63
  64     // Wait for a debugger to come take us.
  65     base::debug::WaitForDebugger(60, false);
  66   } else if (FindArgument(GetCommandLine(), switches::kWaitForDebugger)) {
  67     // Wait for a debugger to come take us.
  68     base::debug::WaitForDebugger(60, true);
  69   }
  70   return 0;
  71 }
  72
  73 }  // namespace debug
  74 }  // namespace base