memory/mozalloc/mozalloc_oom.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * vim: sw=4 ts=4 et :
   3  */
   4 /* This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #if defined(XP_WIN) || defined(XP_OS2)
   9 #  define MOZALLOC_EXPORT __declspec(dllexport)
  10 #endif
  11
  12 #include "mozilla/mozalloc_abort.h"
  13 #include "mozilla/mozalloc_oom.h"
  14 #include "mozilla/Assertions.h"
  15
  16 static mozalloc_oom_abort_handler gAbortHandler;
  17
  18 #define OOM_MSG_LEADER "out of memory: 0x"
  19 #define OOM_MSG_DIGITS "0000000000000000" // large enough for 2^64
  20 #define OOM_MSG_TRAILER " bytes requested"
  21 #define OOM_MSG_FIRST_DIGIT_OFFSET sizeof(OOM_MSG_LEADER) - 1
  22 #define OOM_MSG_LAST_DIGIT_OFFSET sizeof(OOM_MSG_LEADER) + \
  23                                   sizeof(OOM_MSG_DIGITS) - 3
  24
  25 static const char *hex = "0123456789ABCDEF";
  26
  27 void
  28 mozalloc_handle_oom(size_t size)
  29 {
  30     char oomMsg[] = OOM_MSG_LEADER OOM_MSG_DIGITS OOM_MSG_TRAILER;
  31     size_t i;
  32
  33     // NB: this is handle_oom() stage 1, which simply aborts on OOM.
  34     // we might proceed to a stage 2 in which an attempt is made to
  35     // reclaim memory
  36
  37     if (gAbortHandler)
  38         gAbortHandler(size);
  39
  40     static_assert(OOM_MSG_FIRST_DIGIT_OFFSET > 0,
  41                   "Loop below will never terminate (i can't go below 0)");
  42
  43     // Insert size into the diagnostic message using only primitive operations
  44     for (i = OOM_MSG_LAST_DIGIT_OFFSET;
  45          size && i >= OOM_MSG_FIRST_DIGIT_OFFSET; i--) {
  46       oomMsg[i] = hex[size % 16];
  47       size /= 16;
  48     }
  49
  50     mozalloc_abort(oomMsg);
  51 }
  52
  53 void
  54 mozalloc_set_oom_abort_handler(mozalloc_oom_abort_handler handler)
  55 {
  56     gAbortHandler = handler;
  57 }