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