debug_on_start_win.cc revision 3f50c38dc070f4bb515c1b64450dae14f316474e 
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
13namespace base {
14namespace 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.
22bool 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
53int __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
75