media/base/decoder_buffer.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/base/decoder_buffer.h"

#include "base/debug/alias.h"

namespace media {

// Allocates a block of memory which is padded for use with the SIMD
// optimizations used by FFmpeg.
static uint8_t* AllocateFFmpegSafeBlock(size_t size) {
  uint8_t* const block = reinterpret_cast<uint8_t*>(base::AlignedAlloc(
      size + DecoderBuffer::kPaddingSize, DecoderBuffer::kAlignmentSize));
  memset(block + size, 0, DecoderBuffer::kPaddingSize);
  return block;
}

DecoderBuffer::DecoderBuffer(size_t size)
    : size_(size), side_data_size_(0), is_key_frame_(false) {
  Initialize();
}

DecoderBuffer::DecoderBuffer(const uint8_t* data,
                             size_t size,
                             const uint8_t* side_data,
                             size_t side_data_size)
    : size_(size), side_data_size_(side_data_size), is_key_frame_(false) {
  if (!data) {
    CHECK_EQ(size_, 0u);
    CHECK(!side_data);
    return;
  }

  Initialize();

  memcpy(data_.get(), data, size_);

  if (!side_data) {
    CHECK_EQ(side_data_size, 0u);
    return;
  }

  DCHECK_GT(side_data_size_, 0u);
  memcpy(side_data_.get(), side_data, side_data_size_);
}

DecoderBuffer::DecoderBuffer(std::unique_ptr<UnalignedSharedMemory> shm,
                             size_t size)
    : size_(size),
      side_data_size_(0),
      shm_(std::move(shm)),
      is_key_frame_(false) {}

DecoderBuffer::DecoderBuffer(
    std::unique_ptr<ReadOnlyUnalignedMapping> shared_mem_mapping,
    size_t size)
    : size_(size),
      side_data_size_(0),
      shared_mem_mapping_(std::move(shared_mem_mapping)),
      is_key_frame_(false) {}

DecoderBuffer::~DecoderBuffer() {
  // TODO(crbug.com/794740). As a lot of the crashes have |side_data_size_|
  // == 0 yet |side_data| is not null, check that here hoping to get better
  // minidumps. This check verifies that size == 0 and |side_data_| is null,
  // or size != 0 and |side_data_| not null. Also alias several of the
  // objects values to ensure they get saved in the minidump.
  size_t size = size_;
  base::debug::Alias(&size);
  uint8_t* data = data_.get();
  base::debug::Alias(&data);
  size_t side_data_size = side_data_size_;
  base::debug::Alias(&side_data_size);
  uint8_t* side_data = side_data_.get();
  base::debug::Alias(&side_data);
  void* data_at_initialize = data_at_initialize_;
  base::debug::Alias(&data_at_initialize);

  uint32_t destruction = destruction_;
  base::debug::Alias(&destruction);
  CHECK_NE(destruction_, 0xAAAAAAAA);
  destruction_ = 0xAAAAAAAA;

  CHECK_EQ(!!side_data_size_, !!side_data_);
  data_.reset();
  side_data_.reset();
}

void DecoderBuffer::Initialize() {
  data_.reset(AllocateFFmpegSafeBlock(size_));
  data_at_initialize_ = data_.get();
  if (side_data_size_ > 0)
    side_data_.reset(AllocateFFmpegSafeBlock(side_data_size_));
}

// static
scoped_refptr<DecoderBuffer> DecoderBuffer::CopyFrom(const uint8_t* data,
                                                     size_t data_size) {
  // If you hit this CHECK you likely have a bug in a demuxer. Go fix it.
  CHECK(data);
  return base::WrapRefCounted(new DecoderBuffer(data, data_size, NULL, 0));
}

// static
scoped_refptr<DecoderBuffer> DecoderBuffer::CopyFrom(const uint8_t* data,
                                                     size_t data_size,
                                                     const uint8_t* side_data,
                                                     size_t side_data_size) {
  // If you hit this CHECK you likely have a bug in a demuxer. Go fix it.
  CHECK(data);
  CHECK(side_data);
  return base::WrapRefCounted(
      new DecoderBuffer(data, data_size, side_data, side_data_size));
}

// static
scoped_refptr<DecoderBuffer> DecoderBuffer::FromSharedMemoryRegion(
    base::subtle::PlatformSharedMemoryRegion region,
    off_t offset,
    size_t size) {
  // TODO(crbug.com/795291): when clients have converted to using
  // base::ReadOnlySharedMemoryRegion the ugly mode check below will no longer
  // be necessary.
  auto shm = std::make_unique<UnalignedSharedMemory>(
      std::move(region), size,
      region.GetMode() ==
              base::subtle::PlatformSharedMemoryRegion::Mode::kReadOnly
          ? true
          : false);
  if (size == 0 || !shm->MapAt(offset, size))
    return nullptr;
  return base::WrapRefCounted(new DecoderBuffer(std::move(shm), size));
}

// static
scoped_refptr<DecoderBuffer> DecoderBuffer::FromSharedMemoryRegion(
    base::ReadOnlySharedMemoryRegion region,
    off_t offset,
    size_t size) {
  std::unique_ptr<ReadOnlyUnalignedMapping> unaligned_mapping =
      std::make_unique<ReadOnlyUnalignedMapping>(region, size, offset);
  if (!unaligned_mapping->IsValid())
    return nullptr;
  return base::WrapRefCounted(
      new DecoderBuffer(std::move(unaligned_mapping), size));
}

// static
scoped_refptr<DecoderBuffer> DecoderBuffer::CreateEOSBuffer() {
  return base::WrapRefCounted(new DecoderBuffer(NULL, 0, NULL, 0));
}

bool DecoderBuffer::MatchesForTesting(const DecoderBuffer& buffer) const {
  if (end_of_stream() != buffer.end_of_stream())
    return false;

  // It is illegal to call any member function if eos is true.
  if (end_of_stream())
    return true;

  if (timestamp() != buffer.timestamp() || duration() != buffer.duration() ||
      is_key_frame() != buffer.is_key_frame() ||
      discard_padding() != buffer.discard_padding() ||
      data_size() != buffer.data_size() ||
      side_data_size() != buffer.side_data_size()) {
    return false;
  }

  if (memcmp(data(), buffer.data(), data_size()) != 0 ||
      memcmp(side_data(), buffer.side_data(), side_data_size()) != 0) {
    return false;
  }

  if ((decrypt_config() == nullptr) != (buffer.decrypt_config() == nullptr))
    return false;

  return decrypt_config() ? decrypt_config()->Matches(*buffer.decrypt_config())
                          : true;
}

std::string DecoderBuffer::AsHumanReadableString() const {
  if (end_of_stream())
    return "EOS";

  std::ostringstream s;
  s << "timestamp=" << timestamp_.InMicroseconds()
    << " duration=" << duration_.InMicroseconds() << " size=" << size_
    << " side_data_size=" << side_data_size_
    << " is_key_frame=" << is_key_frame_
    << " encrypted=" << (decrypt_config_ != NULL) << " discard_padding (us)=("
    << discard_padding_.first.InMicroseconds() << ", "
    << discard_padding_.second.InMicroseconds() << ")";

  if (decrypt_config_)
    s << " decrypt=" << (*decrypt_config_);

  return s.str();
}

void DecoderBuffer::set_timestamp(base::TimeDelta timestamp) {
  DCHECK(!end_of_stream());
  timestamp_ = timestamp;
}

void DecoderBuffer::CopySideDataFrom(const uint8_t* side_data,
                                     size_t side_data_size) {
  if (side_data_size > 0) {
    side_data_size_ = side_data_size;
    side_data_.reset(AllocateFFmpegSafeBlock(side_data_size_));
    memcpy(side_data_.get(), side_data, side_data_size_);
  } else {
    side_data_.reset();
    side_data_size_ = 0;
  }
}

}  // namespace media