Box.h - mozsearch

Enable keyboard shortcuts

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim:set ts=2 sw=2 sts=2 et cindent: */

/* 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/. */

#ifndef BOX_H_

#define BOX_H_

#include <stdint.h>

#include "nsTArray.h"

#include "MediaResource.h"

#include "mozilla/EndianUtils.h"

#include "AtomType.h"

#include "BufferReader.h"

namespace mozilla {

class ByteStream;

class BumpAllocator {

 public:

  uint8_t* Allocate(size_t aNumBytes);

 private:

  nsTArray<nsTArray<uint8_t>> mBuffers;

};

class BoxContext {

 public:

  BoxContext(ByteStream* aSource, const MediaByteRangeSet& aByteRanges)

      : mSource(aSource), mByteRanges(aByteRanges) {}

  RefPtr<ByteStream> mSource;

  const MediaByteRangeSet& mByteRanges;

  BumpAllocator mAllocator;

};

struct ByteSlice {

  const uint8_t* mBytes;

  size_t mSize;

};

class Box {

 public:

  Box(BoxContext* aContext, uint64_t aOffset, const Box* aParent = nullptr);

  Box();

  bool IsAvailable() const { return !mRange.IsEmpty(); }

  uint64_t Offset() const { return mRange.mStart; }

  uint64_t Length() const { return mRange.mEnd - mRange.mStart; }

  uint64_t NextOffset() const { return mRange.mEnd; }

  const MediaByteRange& Range() const { return mRange; }

  const Box* Parent() const { return mParent; }

  bool IsType(const char* aType) const { return mType == AtomType(aType); }

  Box Next() const;

  Box FirstChild() const;

  // Reads the box contents, excluding the header.

  nsTArray<uint8_t> Read() const;

  // Reads the complete box; its header and body.

  nsTArray<uint8_t> ReadCompleteBox() const;

  // Reads from the content of the box, excluding header.

  bool Read(nsTArray<uint8_t>* aDest, const MediaByteRange& aRange) const;

  static const uint64_t kMAX_BOX_READ;

  // Returns a slice, pointing to the data of this box. The lifetime of

  // the memory this slice points to matches the box's context's lifetime.

  ByteSlice ReadAsSlice();

 private:

  bool Contains(MediaByteRange aRange) const;

  BoxContext* mContext;

  mozilla::MediaByteRange mRange;

  uint64_t mBodyOffset;

  uint64_t mChildOffset;

  AtomType mType;

  const Box* mParent;

};

// BoxReader serves box data through an AutoByteReader. The box data is

// stored either in the box's context's bump allocator, or in the ByteStream

// itself if the ByteStream implements the Access() method.

// NOTE: The data the BoxReader reads may be stored in the Box's BoxContext.

// Ensure that the BoxReader doesn't outlive the BoxContext!

class MOZ_RAII BoxReader {

 public:

  explicit BoxReader(Box& aBox)

      : mData(aBox.ReadAsSlice()), mReader(mData.mBytes, mData.mSize) {}

  BufferReader* operator->() { return &mReader; }

 private:

  ByteSlice mData;

  BufferReader mReader;

};

}  // namespace mozilla

#endif