Line data    Source code

       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             : #include "mozilla/mozalloc_abort.h"
       9             : #include "mozilla/mozalloc_oom.h"
      10             : #include "mozilla/Assertions.h"
      11             : 
      12             : static mozalloc_oom_abort_handler gAbortHandler;
      13             : 
      14             : #define OOM_MSG_LEADER "out of memory: 0x"
      15             : #define OOM_MSG_DIGITS "0000000000000000" // large enough for 2^64
      16             : #define OOM_MSG_TRAILER " bytes requested"
      17             : #define OOM_MSG_FIRST_DIGIT_OFFSET sizeof(OOM_MSG_LEADER) - 1
      18             : #define OOM_MSG_LAST_DIGIT_OFFSET sizeof(OOM_MSG_LEADER) + \
      19             :                                   sizeof(OOM_MSG_DIGITS) - 3
      20             : 
      21             : static const char *hex = "0123456789ABCDEF";
      22             : 
      23             : void
      24           0 : mozalloc_handle_oom(size_t size)
      25             : {
      26           0 :     char oomMsg[] = OOM_MSG_LEADER OOM_MSG_DIGITS OOM_MSG_TRAILER;
      27             :     size_t i;
      28             : 
      29             :     // NB: this is handle_oom() stage 1, which simply aborts on OOM.
      30             :     // we might proceed to a stage 2 in which an attempt is made to
      31             :     // reclaim memory
      32             :     // Warning: when stage 2 is done by, for example, notifying
      33             :     // "memory-pressure" synchronously, please audit all
      34             :     // nsExpirationTrackers and ensure that the actions they take
      35             :     // on memory-pressure notifications (via NotifyExpired) are safe.
      36             :     // Note that nsIDocument::SelectorCache::NotifyExpired is _known_
      37             :     // to not be safe: it will delete the selector it's caching,
      38             :     // which might be in use at the time under querySelector or
      39             :     // querySelectorAll.
      40             : 
      41           0 :     if (gAbortHandler)
      42           0 :         gAbortHandler(size);
      43             : 
      44             :     static_assert(OOM_MSG_FIRST_DIGIT_OFFSET > 0,
      45             :                   "Loop below will never terminate (i can't go below 0)");
      46             : 
      47             :     // Insert size into the diagnostic message using only primitive operations
      48           0 :     for (i = OOM_MSG_LAST_DIGIT_OFFSET;
      49           0 :          size && i >= OOM_MSG_FIRST_DIGIT_OFFSET; i--) {
      50           0 :       oomMsg[i] = hex[size % 16];
      51           0 :       size /= 16;
      52             :     }
      53             : 
      54           0 :     mozalloc_abort(oomMsg);
      55             : }
      56             : 
      57             : void
      58           0 : mozalloc_set_oom_abort_handler(mozalloc_oom_abort_handler handler)
      59             : {
      60           0 :     gAbortHandler = handler;
      61           0 : }