aboutsummaryrefslogtreecommitdiff
path: root/src/client/windows/handler/exception_handler.cc
blob: 10d5ec086b5ec26d96c35591669a3a0d6b84b4e0 (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
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
// Copyright (c) 2006, Google Inc.
// All rights reserved.
//
// 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.

#include <ObjBase.h>

#include <cassert>
#include <cstdio>

#include "common/windows/string_utils-inl.h"

#include "client/windows/handler/exception_handler.h"
#include "common/windows/guid_string.h"
#include "google_airbag/common/minidump_format.h"

namespace google_airbag {

static const int kExceptionHandlerThreadInitialStackSize = 64 * 1024;

vector<ExceptionHandler *> *ExceptionHandler::handler_stack_ = NULL;
LONG ExceptionHandler::handler_stack_index_ = 0;
CRITICAL_SECTION ExceptionHandler::handler_stack_critical_section_;
bool ExceptionHandler::handler_stack_critical_section_initialized_ = false;

ExceptionHandler::ExceptionHandler(const wstring &dump_path,
                                   FilterCallback filter,
                                   MinidumpCallback callback,
                                   void *callback_context,
                                   bool install_handler)
    : filter_(filter),
      callback_(callback),
      callback_context_(callback_context),
      dump_path_(),
      next_minidump_id_(),
      next_minidump_path_(),
      dump_path_c_(),
      next_minidump_id_c_(NULL),
      next_minidump_path_c_(NULL),
      dbghelp_module_(NULL),
      minidump_write_dump_(NULL),
      installed_handler_(install_handler),
      previous_filter_(NULL),
      handler_thread_(0),
      handler_critical_section_(),
      handler_start_semaphore_(NULL),
      handler_finish_semaphore_(NULL),
      requesting_thread_id_(0),
      exception_info_(NULL),
      handler_return_value_(false) {
  // set_dump_path calls UpdateNextID.  This sets up all of the path and id
  // strings, and their equivalent c_str pointers.
  set_dump_path(dump_path);

  // Set synchronization primitives and the handler thread.  Each
  // ExceptionHandler object gets its own handler thread, even if
  // install_handler is false, because that's the only way to reliably
  // guarantee sufficient stack space in an exception, and the only way to
  // get a snapshot of the requesting thread's context outside of an
  // exception.
  InitializeCriticalSection(&handler_critical_section_);
  handler_start_semaphore_ = CreateSemaphore(NULL, 0, 1, NULL);
  handler_finish_semaphore_ = CreateSemaphore(NULL, 0, 1, NULL);

  DWORD thread_id;
  handler_thread_ = CreateThread(NULL,         // lpThreadAttributes
                                 kExceptionHandlerThreadInitialStackSize,
                                 ExceptionHandlerThreadMain,
                                 this,         // lpParameter
                                 0,            // dwCreationFlags
                                 &thread_id);

  dbghelp_module_ = LoadLibrary(L"dbghelp.dll");
  if (dbghelp_module_) {
    minidump_write_dump_ = reinterpret_cast<MiniDumpWriteDump_type>(
        GetProcAddress(dbghelp_module_, "MiniDumpWriteDump"));
  }

  if (install_handler) {
    if (!handler_stack_critical_section_initialized_) {
      InitializeCriticalSection(&handler_stack_critical_section_);
      handler_stack_critical_section_initialized_ = true;
    }

    EnterCriticalSection(&handler_stack_critical_section_);

    // The first time an ExceptionHandler that installs a handler is
    // created, set up the handler stack.
    if (!handler_stack_) {
      handler_stack_ = new vector<ExceptionHandler *>();
    }
    handler_stack_->push_back(this);
    previous_filter_ = SetUnhandledExceptionFilter(HandleException);

    LeaveCriticalSection(&handler_stack_critical_section_);
  }
}

ExceptionHandler::~ExceptionHandler() {
  if (dbghelp_module_) {
    FreeLibrary(dbghelp_module_);
  }

  if (installed_handler_) {
    EnterCriticalSection(&handler_stack_critical_section_);

    SetUnhandledExceptionFilter(previous_filter_);
    if (handler_stack_->back() == this) {
      handler_stack_->pop_back();
    } else {
      // TODO(mmentovai): use advapi32!ReportEvent to log the warning to the
      // system's application event log.
      fprintf(stderr, "warning: removing Airbag handler out of order\n");
      for (vector<ExceptionHandler *>::iterator iterator =
               handler_stack_->begin();
           iterator != handler_stack_->end();
           ++iterator) {
        if (*iterator == this) {
          handler_stack_->erase(iterator);
        }
      }
    }

    if (handler_stack_->empty()) {
      // When destroying the last ExceptionHandler that installed a handler,
      // clean up the handler stack.
      delete handler_stack_;
      handler_stack_ = NULL;
    }

    LeaveCriticalSection(&handler_stack_critical_section_);
  }

  // Clean up the handler thread and synchronization primitives.
  TerminateThread(handler_thread_, 1);
  DeleteCriticalSection(&handler_critical_section_);
  CloseHandle(handler_start_semaphore_);
  CloseHandle(handler_finish_semaphore_);
}

// static
DWORD ExceptionHandler::ExceptionHandlerThreadMain(void *lpParameter) {
  ExceptionHandler *self = reinterpret_cast<ExceptionHandler *>(lpParameter);
  assert(self);

  while (true) {
    if (WaitForSingleObject(self->handler_start_semaphore_, INFINITE) ==
        WAIT_OBJECT_0) {
      // Perform the requested action.
      self->handler_return_value_ = self->WriteMinidumpWithException(
          self->requesting_thread_id_, self->exception_info_);

      // Allow the requesting thread to proceed.
      ReleaseSemaphore(self->handler_finish_semaphore_, 1, NULL);
    }
  }

  // Not reached.  This thread will be terminated by ExceptionHandler's
  // destructor.
  return 0;
}

// static
LONG ExceptionHandler::HandleException(EXCEPTION_POINTERS *exinfo) {
  // Increment handler_stack_index_ so that if another Airbag handler is
  // registered using this same HandleException function, and it needs to be
  // called while this handler is running (either becaause this handler
  // declines to handle the exception, or an exception occurs during
  // handling), HandleException will find the appropriate ExceptionHandler
  // object in handler_stack_ to deliver the exception to.
  //
  // Because handler_stack_ is addressed in reverse (as |size - index|),
  // preincrementing handler_stack_index_ avoids needing to subtract 1 from
  // the argument to |at|.
  //
  // The index is maintained instead of popping elements off of the handler
  // stack and pushing them at the end of this method.  This avoids ruining
  // the order of elements in the stack in the event that some other thread
  // decides to manipulate the handler stack (such as creating a new
  // ExceptionHandler object) while an exception is being handled.
  EnterCriticalSection(&handler_stack_critical_section_);
  ExceptionHandler *current_handler =
      handler_stack_->at(handler_stack_->size() - ++handler_stack_index_);
  LeaveCriticalSection(&handler_stack_critical_section_);

  // In case another exception occurs while this handler is doing its thing,
  // it should be delivered to the previous filter.
  LPTOP_LEVEL_EXCEPTION_FILTER previous = current_handler->previous_filter_;
  LPTOP_LEVEL_EXCEPTION_FILTER restore = SetUnhandledExceptionFilter(previous);

  LONG action;
  if (current_handler->WriteMinidumpOnHandlerThread(exinfo)) {
    // The handler fully handled the exception.  Returning
    // EXCEPTION_EXECUTE_HANDLER indicates this to the system, and usually
    // results in the applicaiton being terminated.
    //
    // Note: If the application was launched from within the Cygwin
    // environment, returning EXCEPTION_EXECUTE_HANDLER seems to cause the
    // application to be restarted.
    action = EXCEPTION_EXECUTE_HANDLER;
  } else {
    // There was an exception, but the handler decided not to handle it.
    // This could be because the filter callback didn't want it, because
    // minidump writing failed for some reason, or because the post-minidump
    // callback function indicated failure.  Give the previous handler a
    // chance to do something with the exception.  If there is no previous
    // handler, return EXCEPTION_CONTINUE_SEARCH, which will allow a debugger
    // or native "crashed" dialog to handle the exception.
    action = previous ? previous(exinfo) : EXCEPTION_CONTINUE_SEARCH;
  }

  // Put things back the way they were before entering this handler.
  SetUnhandledExceptionFilter(restore);
  EnterCriticalSection(&handler_stack_critical_section_);
  --handler_stack_index_;
  LeaveCriticalSection(&handler_stack_critical_section_);

  return action;
}

bool ExceptionHandler::WriteMinidumpOnHandlerThread(EXCEPTION_POINTERS *exinfo) {
  EnterCriticalSection(&handler_critical_section_);

  // Set up data to be passed in to the handler thread.
  requesting_thread_id_ = GetCurrentThreadId();
  exception_info_ = exinfo;

  // This causes the handler thread to call WriteMinidumpWithException.
  ReleaseSemaphore(handler_start_semaphore_, 1, NULL);

  // Wait until WriteMinidumpWithException is done and collect its return value.
  WaitForSingleObject(handler_finish_semaphore_, INFINITE);
  bool status = handler_return_value_;

  // Clean up.
  requesting_thread_id_ = 0;
  exception_info_ = NULL;

  LeaveCriticalSection(&handler_critical_section_);

  return status;
}

bool ExceptionHandler::WriteMinidump() {
  bool success = WriteMinidumpOnHandlerThread(NULL);
  UpdateNextID();
  return success;
}

// static
bool ExceptionHandler::WriteMinidump(const wstring &dump_path,
                                     MinidumpCallback callback,
                                     void *callback_context) {
  ExceptionHandler handler(dump_path, NULL, callback, callback_context, false);
  return handler.WriteMinidump();
}

bool ExceptionHandler::WriteMinidumpWithException(DWORD requesting_thread_id,
                                                  EXCEPTION_POINTERS *exinfo) {
  // Give user code a chance to approve or prevent writing a minidump.  If the
  // filter returns false, don't handle the exception at all.  If this method
  // was called as a result of an exception, returning false will cause
  // HandleException to call any previous handler or return
  // EXCEPTION_CONTINUE_SEARCH on the exception thread, allowing it to appear
  // as though this handler were not present at all.
  if (filter_&& !filter_(callback_context_)) {
    return false;
  }

  bool success = false;
  if (minidump_write_dump_) {
    HANDLE dump_file = CreateFile(next_minidump_path_c_,
                                  GENERIC_WRITE,
                                  FILE_SHARE_WRITE,
                                  NULL,
                                  CREATE_ALWAYS,
                                  FILE_ATTRIBUTE_NORMAL,
                                  NULL);
    if (dump_file != INVALID_HANDLE_VALUE) {
      MINIDUMP_EXCEPTION_INFORMATION except_info;
      except_info.ThreadId = requesting_thread_id;
      except_info.ExceptionPointers = exinfo;
      except_info.ClientPointers = FALSE;

      // Add an MDRawAirbagInfo stream to the minidump, to provide additional
      // information about the exception handler to the Airbag processor.  The
      // information will help the processor determine which threads are
      // relevant.  The Airbag processor does not require this information but
      // can function better with Airbag-generated dumps when it is present.
      // The native debugger is not harmed by the presence of this information.
      MDRawAirbagInfo airbag_info;
      airbag_info.validity = MD_AIRBAG_INFO_VALID_DUMP_THREAD_ID |
                             MD_AIRBAG_INFO_VALID_REQUESTING_THREAD_ID;
      airbag_info.dump_thread_id = GetCurrentThreadId();
      airbag_info.requesting_thread_id = requesting_thread_id;

      MINIDUMP_USER_STREAM airbag_info_stream;
      airbag_info_stream.Type = MD_AIRBAG_INFO_STREAM;
      airbag_info_stream.BufferSize = sizeof(airbag_info);
      airbag_info_stream.Buffer = &airbag_info;

      MINIDUMP_USER_STREAM_INFORMATION user_streams;
      user_streams.UserStreamCount = 1;
      user_streams.UserStreamArray = &airbag_info_stream;

      // The explicit comparison to TRUE avoids a warning (C4800).
      success = (minidump_write_dump_(GetCurrentProcess(),
                                      GetCurrentProcessId(),
                                      dump_file,
                                      MiniDumpNormal,
                                      exinfo ? &except_info : NULL,
                                      &user_streams,
                                      NULL) == TRUE);

      CloseHandle(dump_file);
    }
  }

  if (callback_) {
    success = callback_(dump_path_c_, next_minidump_id_c_, callback_context_,
                        success);
  }

  return success;
}

void ExceptionHandler::UpdateNextID() {
  GUID id;
  CoCreateGuid(&id);
  next_minidump_id_ = GUIDString::GUIDToWString(&id);
  next_minidump_id_c_ = next_minidump_id_.c_str();

  wchar_t minidump_path[MAX_PATH];
  WindowsStringUtils::safe_swprintf(minidump_path, MAX_PATH, L"%s\\%s.dmp",
                                    dump_path_c_,
                                    next_minidump_id_c_);
  next_minidump_path_ = minidump_path;
  next_minidump_path_c_ = next_minidump_path_.c_str();
}

}  // namespace google_airbag