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 "base/memory/scoped_ptr.h"
  21    :  #include "syzygy/core/serialization.h"
  22    :  
  23    :  // Forward declaration.
  24  m :  struct z_stream_s;
  25    :  
  26  m :  namespace core {
  27    :  
  28    :  // A zlib compressing out-stream. Acts as a filter, accepting the uncompressed
  29    :  // input that is pushed to it, and pushing compressed output to the chained
  30    :  // stream.
  31  m :  class ZOutStream : public OutStream {
  32  m :   public:
  33    :    // @{
  34    :    // Constructor.
  35    :    // @param out_stream the output stream to receive the compressed data.
  36  m :    explicit ZOutStream(OutStream* out_stream);
  37    :    // @}
  38    :  
  39    :    // Destructor.
  40  m :    virtual ~ZOutStream();
  41    :  
  42    :    // These are effectively forwarded from zlib.h.
  43  m :    static const int kZDefaultCompression = -1;
  44  m :    static const int kZNoCompression = 0;
  45  m :    static const int kZBestSpeed = 1;
  46  m :    static const int kZBestCompression = 9;
  47    :  
  48    :    // @{
  49    :    // Initializes this compressor. Must be called prior to calling Write.
  50    :    // @param level the level of compression. Must be kZDefaultCompression (-1),
  51    :    //     or an integer in the range 0..9, inclusive. If not provided defaults to
  52    :    //     Z_DEFAULT_COMPRESSION.
  53    :    // @returns true on success, false otherwise.
  54  m :    bool Init();
  55  m :    bool Init(int level);
  56    :    // @}
  57    :  
  58    :    // @name OutStream implementation.
  59    :    // @{
  60    :    // Writes the given buffer of data to the stream. This may or may not produce
  61    :    // output in the enclosed out-stream.
  62    :    // @param length the number of bytes to write.
  63    :    // @param bytes the buffer of data to write.
  64    :    // @returns true on success, false otherwise.
  65  m :    virtual bool Write(size_t length, const Byte* bytes) override;
  66    :    // After a call to Flush the compressed stream is closed and further calls to
  67    :    // Write will fail. Flush must be called after all writing is finished in
  68    :    // order for the output to be well-formed. This does not recursively call
  69    :    // flush on the child stream.
  70    :    // @returns true on success, false otherwise.
  71  m :    virtual bool Flush() override;
  72    :    // @}
  73    :  
  74  m :   private:
  75    :    // Functor that takes care of cleaning up a zstream object that was
  76    :    // initialized with deflateInit.
  77  m :    struct z_stream_s_close {
  78  m :      inline void operator()(z_stream_s* zstream) const;
  79  m :    };
  80    :  
  81  m :    bool FlushBuffer();
  82    :  
  83  m :    scoped_ptr<z_stream_s, z_stream_s_close> zstream_;
  84  m :    OutStream* out_stream_;
  85  m :    std::vector<uint8> buffer_;
  86  m :  };
  87    :  
  88    :  // A zlib decompressing in-stream, decompressing the data from the chained
  89    :  // input stream and returning decompressed data to the caller.
  90  m :  class ZInStream : public InStream {
  91  m :   public:
  92    :    // Constructor.
  93    :    // @param in_stream the input stream from which we read compressed data.
  94  m :    explicit ZInStream(InStream* in_stream);
  95    :  
  96    :    // Destructor.
  97  m :    virtual ~ZInStream();
  98    :  
  99    :    // Initializes this decompressor. Must be called prior to calling any read
 100    :    // functions.
 101  m :    bool Init();
 102    :  
 103  m :   protected:
 104    :    // InStream implementation.
 105  m :    virtual bool ReadImpl(size_t length,
 106  m :                          Byte* bytes,
 107  m :                          size_t* bytes_read) override;
 108    :  
 109  m :   private:
 110    :    // Functor that takes care of cleaning up a zstream object that was
 111    :    // initialized with inflateInit.
 112  m :    struct z_stream_s_close {
 113  m :      inline void operator()(z_stream_s* zstream) const;
 114  m :    };
 115    :  
 116  m :    scoped_ptr<z_stream_s, z_stream_s_close> zstream_;
 117  m :    InStream* in_stream_;
 118  m :    std::vector<uint8> buffer_;
 119  m :  };
 120    :  
 121  m :  }  // namespace core
 122    :  
 123    :  #endif  // SYZYGY_CORE_ZSTREAM_H_