aboutsummaryrefslogtreecommitdiff
path: root/src/client/linux/handler/exception_handler.h
blob: 2a21231587c533c76f75eacc019295527ce84eec (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
// Copyright (c) 2006, Google Inc.
// All rights reserved.
//
// Author: Li Liu
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H__
#define CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H__

#include <pthread.h>

#include <map>
#include <string>
#include <vector>

#include "client/linux/handler/minidump_generator.h"

// Context information when exception occured.
struct sigcontex;

namespace google_breakpad {

using std::string;

//
// ExceptionHandler
//
// ExceptionHandler can write a minidump file when an exception occurs,
// or when WriteMinidump() is called explicitly by your program.
//
// To have the exception handler write minidumps when an uncaught exception
// (crash) occurs, you should create an instance early in the execution
// of your program, and keep it around for the entire time you want to
// have crash handling active (typically, until shutdown).
// (NOTE): There should be only be one this kind of exception handler
// object per process.
//
// If you want to write minidumps without installing the exception handler,
// you can create an ExceptionHandler with install_handler set to false,
// then call WriteMinidump.  You can also use this technique if you want to
// use different minidump callbacks for different call sites.
//
// In either case, a callback function is called when a minidump is written,
// which receives the unqiue id of the minidump.  The caller can use this
// id to collect and write additional application state, and to launch an
// external crash-reporting application.
//
// Caller should try to make the callbacks as crash-friendly as possible,
// it should avoid use heap memory allocation as much as possible.
//
class ExceptionHandler {
 public:
  // A callback function to run before Breakpad performs any substantial
  // processing of an exception.  A FilterCallback is called before writing
  // a minidump.  context is the parameter supplied by the user as
  // callback_context when the handler was created.
  //
  // If a FilterCallback returns true, Breakpad will continue processing,
  // attempting to write a minidump.  If a FilterCallback returns false,
  // Breakpad  will immediately report the exception as unhandled without
  // writing a minidump, allowing another handler the opportunity to handle it.
  typedef bool (*FilterCallback)(void *context);

  // A callback function to run after the minidump has been written.
  // minidump_id is a unique id for the dump, so the minidump
  // file is <dump_path>\<minidump_id>.dmp.  context is the parameter supplied
  // by the user as callback_context when the handler was created.  succeeded
  // indicates whether a minidump file was successfully written.
  //
  // If an exception occurred and the callback returns true, Breakpad will
  // treat the exception as fully-handled, suppressing any other handlers from
  // being notified of the exception.  If the callback returns false, Breakpad
  // will treat the exception as unhandled, and allow another handler to handle
  // it. If there are no other handlers, Breakpad will report the exception to
  // the system as unhandled, allowing a debugger or native crash dialog the
  // opportunity to handle the exception.  Most callback implementations
  // should normally return the value of |succeeded|, or when they wish to
  // not report an exception of handled, false.  Callbacks will rarely want to
  // return true directly (unless |succeeded| is true).
  typedef bool (*MinidumpCallback)(const char *dump_path,
                                   const char *minidump_id,
                                   void *context,
                                   bool succeeded);

  // Creates a new ExceptionHandler instance to handle writing minidumps.
  // Before writing a minidump, the optional filter callback will be called.
  // Its return value determines whether or not Breakpad should write a
  // minidump.  Minidump files will be written to dump_path, and the optional
  // callback is called after writing the dump file, as described above.
  // If install_handler is true, then a minidump will be written whenever
  // an unhandled exception occurs.  If it is false, minidumps will only
  // be written when WriteMinidump is called.
  ExceptionHandler(const string &dump_path,
                   FilterCallback filter, MinidumpCallback callback,
                   void *callback_context,
                   bool install_handler);
  ~ExceptionHandler();

  // Get and set the minidump path.
  string dump_path() const { return dump_path_; }
  void set_dump_path(const string &dump_path) {
    dump_path_ = dump_path;
    dump_path_c_ = dump_path_.c_str();
  }

  // Writes a minidump immediately.  This can be used to capture the
  // execution state independently of a crash.  Returns true on success.
  bool WriteMinidump();

  // Convenience form of WriteMinidump which does not require an
  // ExceptionHandler instance.
  static bool WriteMinidump(const string &dump_path,
                            MinidumpCallback callback,
                            void *callback_context);

 private:
  // Setup crash handler.
  void SetupHandler();
  // Setup signal handler for a signal.
  void SetupHandler(int signo);
  // Teardown the handler for a signal.
  void TeardownHandler(int signo);
  // Teardown all handlers.
  void TeardownAllHandler();

  // Signal handler.
  static void HandleException(int signo);

  // If called from a signal handler, sighandler_ebp is the ebp of
  // that signal handler's frame, and sig_ctx is an out parameter
  // that will be set to point at the sigcontext that was placed
  // on the stack by the kernel.  You can pass zero and NULL
  // for the second and third parameters if you are not calling
  // this from a signal handler.
  bool InternalWriteMinidump(int signo, uintptr_t sighandler_ebp,
                             struct sigcontext **sig_ctx);

 private:
  FilterCallback filter_;
  MinidumpCallback callback_;
  void *callback_context_;

  // The directory in which a minidump will be written, set by the dump_path
  // argument to the constructor, or set_dump_path.
  string dump_path_;
  // C style dump path. Keep this when setting dump path, since calling
  // c_str() of std::string when crashing may not be safe.
  const char *dump_path_c_;

  // True if the ExceptionHandler installed an unhandled exception filter
  // when created (with an install_handler parameter set to true).
  bool installed_handler_;

  // Keep the previous handlers for the signal.
  typedef void (*sighandler_t)(int);
  std::map<int, sighandler_t> old_handlers_;

  // The global exception handler stack. This is need becuase there may exist
  // multiple ExceptionHandler instances in a process. Each will have itself
  // registered in this stack.
  static std::vector<ExceptionHandler *> *handler_stack_;
  // The index of the handler that should handle the next exception.
  static int handler_stack_index_;
  static pthread_mutex_t handler_stack_mutex_;

  // The minidump generator.
  MinidumpGenerator minidump_generator_;

  // disallow copy ctor and operator=
  explicit ExceptionHandler(const ExceptionHandler &);
  void operator=(const ExceptionHandler &);
};

}  // namespace google_breakpad

#endif  // CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H__