src/include/puffin/puffer.h

// Copyright 2017 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_INCLUDE_PUFFIN_PUFFER_H_
#define SRC_INCLUDE_PUFFIN_PUFFER_H_

#include <memory>
#include <vector>

#include "puffin/common.h"
#include "puffin/stream.h"

namespace puffin {

class BitReaderInterface;
class PuffWriterInterface;
class HuffmanTable;

class Puffer {
 public:
  // In older versions of puffin, there is a bug in the client which incorrectly
  // identifies the number of bits to cache when number of bits for the current
  // distance plus the number of bits for end of block Huffman code is smaller
  // than the maximum number of bits needed for distance. If this situations
  // happens at the very end of the block, it incorrectly tries to cache more
  // bits than we have and crashes as a result. If |exclude_bad_distance_caches|
  // is true, we identify those problematic deflate buffers and exclude them
  // from the list of available deflates. The default is false.
  explicit Puffer(bool exclude_bad_distance_caches);
  Puffer();
  ~Puffer();

  // Creates a puffed buffer from a deflate buffer.
  //
  // If |deflates| is not null, it will be populated with the location of the
  // subblocks in the input data. In addition, the uncompressed deflate blocks
  // will be ignored and will not be added to the |deflates|. For this case to
  // happen correctly, the |pw| should write into an empty/null buffer,
  // otherwise the created puff stream, will not match the deflate stream. In
  // addition, in this case, the function will return when it reaches a final
  // deflate subblock.
  bool PuffDeflate(BitReaderInterface* br,
                   PuffWriterInterface* pw,
                   std::vector<BitExtent>* deflates) const;

 private:
  std::unique_ptr<HuffmanTable> dyn_ht_;
  std::unique_ptr<HuffmanTable> fix_ht_;

  bool exclude_bad_distance_caches_;

  DISALLOW_COPY_AND_ASSIGN(Puffer);
};

}  // namespace puffin

#endif  // SRC_INCLUDE_PUFFIN_PUFFER_H_