mfbt/Assertions.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   4  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "mozilla/Assertions.h"
   7 #include "mozilla/Atomics.h"
   8
   9 #include <stdarg.h>
  10
  11 MOZ_BEGIN_EXTERN_C
  12
  13 /*
  14  * The crash reason is defined as a global variable here rather than in the
  15  * crash reporter itself to make it available to all code, even libraries like
  16  * JS that don't link with the crash reporter directly. This value will only
  17  * be consumed if the crash reporter is used by the target application.
  18  */
  19 MFBT_DATA const char* gMozCrashReason = nullptr;
  20
  21 static char sPrintfCrashReason[sPrintfCrashReasonSize] = {};
  22
  23 // Accesses to this atomic are not included in web replay recordings, so that
  24 // if we crash in an area where recorded events are not allowed the true reason
  25 // for the crash is not obscured by a record/replay error.
  26 static mozilla::Atomic<bool, mozilla::SequentiallyConsistent> sCrashing(false);
  27
  28 MFBT_API MOZ_COLD MOZ_NEVER_INLINE MOZ_FORMAT_PRINTF(1, 2) const
  29     char* MOZ_CrashPrintf(const char* aFormat, ...) {
  30   if (!sCrashing.compareExchange(false, true)) {
  31     // In the unlikely event of a race condition, skip
  32     // setting the crash reason and just crash safely.
  33     MOZ_RELEASE_ASSERT(false);
  34   }
  35   va_list aArgs;
  36   va_start(aArgs, aFormat);
  37   int ret =
  38       vsnprintf(sPrintfCrashReason, sPrintfCrashReasonSize, aFormat, aArgs);
  39   va_end(aArgs);
  40   MOZ_RELEASE_ASSERT(
  41       ret >= 0 && size_t(ret) < sPrintfCrashReasonSize,
  42       "Could not write the explanation string to the supplied buffer!");
  43   return sPrintfCrashReason;
  44 }
  45
  46 MOZ_END_EXTERN_C