1    :  // Copyright 2012 Google Inc. All Rights Reserved.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  //
  15    :  // Defines simple streams which can zlib compress or decompress data.
  16    :  
  17    :  #ifndef SYZYGY_CORE_ZSTREAM_H_
  18    :  #define SYZYGY_CORE_ZSTREAM_H_
  19    :  
  20    :  #include <memory>
  21    :  
  22    :  #include "syzygy/core/serialization.h"
  23    :  
  24    :  // Forward declaration.
  25  m :  struct z_stream_s;
  26    :  
  27  m :  namespace core {
  28    :  
  29    :  // A zlib compressing out-stream. Acts as a filter, accepting the uncompressed
  30    :  // input that is pushed to it, and pushing compressed output to the chained
  31    :  // stream.
  32  m :  class ZOutStream : public OutStream {
  33  m :   public:
  34    :    // @{
  35    :    // Constructor.
  36    :    // @param out_stream the output stream to receive the compressed data.
  37  m :    explicit ZOutStream(OutStream* out_stream);
  38    :    // @}
  39    :  
  40    :    // Destructor.
  41  m :    virtual ~ZOutStream();
  42    :  
  43    :    // These are effectively forwarded from zlib.h.
  44  m :    static const int kZDefaultCompression = -1;
  45  m :    static const int kZNoCompression = 0;
  46  m :    static const int kZBestSpeed = 1;
  47  m :    static const int kZBestCompression = 9;
  48    :  
  49    :    // @{
  50    :    // Initializes this compressor. Must be called prior to calling Write.
  51    :    // @param level the level of compression. Must be kZDefaultCompression (-1),
  52    :    //     or an integer in the range 0..9, inclusive. If not provided defaults to
  53    :    //     Z_DEFAULT_COMPRESSION.
  54    :    // @returns true on success, false otherwise.
  55  m :    bool Init();
  56  m :    bool Init(int level);
  57    :    // @}
  58    :  
  59    :    // @name OutStream implementation.
  60    :    // @{
  61    :    // Writes the given buffer of data to the stream. This may or may not produce
  62    :    // output in the enclosed out-stream.
  63    :    // @param length the number of bytes to write.
  64    :    // @param bytes the buffer of data to write.
  65    :    // @returns true on success, false otherwise.
  66  m :    virtual bool Write(size_t length, const Byte* bytes) override;
  67    :    // After a call to Flush the compressed stream is closed and further calls to
  68    :    // Write will fail. Flush must be called after all writing is finished in
  69    :    // order for the output to be well-formed. This does not recursively call
  70    :    // flush on the child stream.
  71    :    // @returns true on success, false otherwise.
  72  m :    virtual bool Flush() override;
  73    :    // @}
  74    :  
  75  m :   private:
  76    :    // Functor that takes care of cleaning up a zstream object that was
  77    :    // initialized with deflateInit.
  78  m :    struct z_stream_s_close {
  79  m :      inline void operator()(z_stream_s* zstream) const;
  80  m :    };
  81    :  
  82  m :    bool FlushBuffer();
  83    :  
  84  m :    std::unique_ptr<z_stream_s, z_stream_s_close> zstream_;
  85  m :    OutStream* out_stream_;
  86  m :    std::vector<uint8_t> buffer_;
  87  m :  };
  88    :  
  89    :  // A zlib decompressing in-stream, decompressing the data from the chained
  90    :  // input stream and returning decompressed data to the caller.
  91  m :  class ZInStream : public InStream {
  92  m :   public:
  93    :    // Constructor.
  94    :    // @param in_stream the input stream from which we read compressed data.
  95  m :    explicit ZInStream(InStream* in_stream);
  96    :  
  97    :    // Destructor.
  98  m :    virtual ~ZInStream();
  99    :  
 100    :    // Initializes this decompressor. Must be called prior to calling any read
 101    :    // functions.
 102  m :    bool Init();
 103    :  
 104  m :   protected:
 105    :    // InStream implementation.
 106  m :    virtual bool ReadImpl(size_t length,
 107  m :                          Byte* bytes,
 108  m :                          size_t* bytes_read) override;
 109    :  
 110  m :   private:
 111    :    // Functor that takes care of cleaning up a zstream object that was
 112    :    // initialized with inflateInit.
 113  m :    struct z_stream_s_close {
 114  m :      inline void operator()(z_stream_s* zstream) const;
 115  m :    };
 116    :  
 117  m :    std::unique_ptr<z_stream_s, z_stream_s_close> zstream_;
 118  m :    InStream* in_stream_;
 119  m :    std::vector<uint8_t> buffer_;
 120  m :  };
 121    :  
 122  m :  }  // namespace core
 123    :  
 124    :  #endif  // SYZYGY_CORE_ZSTREAM_H_