mfbt/Compression.cpp
author Andrew Osmond <aosmond@mozilla.com>
Tue, 24 Apr 2018 13:51:35 -0400
changeset 415325 1173dccd114e1c86047a6f01e341cf1c4ea8fe9c
parent 392105 6f31b7226512260726dbd618b94751024a06909f
child 448947 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1444537 - Part 3. Fix how redecode errors could cause animated image state inconsistencies. r=tnikkel We can discard frames from an animated image if the memory footprint exceeds the threshold. This will cause us to redecode frames on demand instead. However decoders can fail to produce the same results on subsequent runs due to differences in memory pressure, etc. If this happens our state can get inconsistent. In particular, if we keep failing on the first frame, we end up in an infinite loop on the decoder thread. Since we don't have the owning image to signal, as we had to release our reference to it after the first pass, we can do little but stop decoding. From the user's perspective, the animation will come to a stop.

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/Compression.h"
#include "mozilla/CheckedInt.h"

// Without including <string>, MSVC 2015 complains about e.g. the impossibility
// to convert `const void* const` to `void*` when calling memchr from
// corecrt_memory.h.
#include <string>

#include "lz4.h"

using namespace mozilla::Compression;

/* Our wrappers */

size_t
LZ4::compress(const char* aSource, size_t aInputSize, char* aDest)
{
  CheckedInt<int> inputSizeChecked = aInputSize;
  MOZ_ASSERT(inputSizeChecked.isValid());
  return LZ4_compress_default(aSource, aDest, inputSizeChecked.value(),
                              LZ4_compressBound(inputSizeChecked.value()));
}

size_t
LZ4::compressLimitedOutput(const char* aSource, size_t aInputSize, char* aDest,
                           size_t aMaxOutputSize)
{
  CheckedInt<int> inputSizeChecked = aInputSize;
  MOZ_ASSERT(inputSizeChecked.isValid());
  CheckedInt<int> maxOutputSizeChecked = aMaxOutputSize;
  MOZ_ASSERT(maxOutputSizeChecked.isValid());
  return LZ4_compress_default(aSource, aDest, inputSizeChecked.value(),
                              maxOutputSizeChecked.value());
}

bool
LZ4::decompress(const char* aSource, char* aDest, size_t aOutputSize)
{
  CheckedInt<int> outputSizeChecked = aOutputSize;
  MOZ_ASSERT(outputSizeChecked.isValid());
  int ret = LZ4_decompress_fast(aSource, aDest, outputSizeChecked.value());
  return ret >= 0;
}

bool
LZ4::decompress(const char* aSource, size_t aInputSize, char* aDest,
                size_t aMaxOutputSize, size_t* aOutputSize)
{
  CheckedInt<int> maxOutputSizeChecked = aMaxOutputSize;
  MOZ_ASSERT(maxOutputSizeChecked.isValid());
  CheckedInt<int> inputSizeChecked = aInputSize;
  MOZ_ASSERT(inputSizeChecked.isValid());

  int ret = LZ4_decompress_safe(aSource, aDest, inputSizeChecked.value(),
                                maxOutputSizeChecked.value());
  if (ret >= 0) {
    *aOutputSize = ret;
    return true;
  }

  *aOutputSize = 0;
  return false;
}

bool
LZ4::decompressPartial(const char* aSource, size_t aInputSize, char* aDest,
                       size_t aMaxOutputSize, size_t* aOutputSize)
{
  CheckedInt<int> maxOutputSizeChecked = aMaxOutputSize;
  MOZ_ASSERT(maxOutputSizeChecked.isValid());
  CheckedInt<int> inputSizeChecked = aInputSize;
  MOZ_ASSERT(inputSizeChecked.isValid());

  int ret = LZ4_decompress_safe_partial(aSource, aDest,
                                        inputSizeChecked.value(),
                                        maxOutputSizeChecked.value(),
                                        maxOutputSizeChecked.value());
  if (ret >= 0) {
    *aOutputSize = ret;
    return true;
  }

  *aOutputSize = 0;
  return false;
}