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/*
* Compression Transform
* (C) 2014 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_COMPRESSION_TRANSFORM_H__
#define BOTAN_COMPRESSION_TRANSFORM_H__
#include <botan/secmem.h>
#include <string>
namespace Botan {
/*
* Interface for a compression algorithm.
*/
class BOTAN_DLL Compression_Algorithm
{
public:
/**
* Begin compressing. Most compression algorithms offer a tunable
* time/compression tradeoff parameter generally represented by
* an integer in the range of 1 to 9.
*
* If 0 or a value out of range is provided, a compression algorithm
* specific default is used.
*/
virtual void start(size_t comp_level = 0) = 0;
/**
* Process some data. Input must be in size update_granularity() byte blocks.
* @param buf in/out parameter which will possibly be resized or swapped
* @param offset an offset into blocks to begin processing
* @param flush if true the compressor will be told to flush state
*/
virtual void update(secure_vector<byte>& buf, size_t offset = 0, bool flush = false) = 0;
/**
* Finish compressing
*
* @param final_block in/out parameter
* @param offset an offset into final_block to begin processing
*/
virtual void finish(secure_vector<byte>& final_block, size_t offset = 0) = 0;
/**
* @return name of the compression algorithm
*/
virtual std::string name() const = 0;
/**
* Reset the state and abort the current message; start can be
* called again to process a new message.
*/
virtual void clear() = 0;
virtual ~Compression_Algorithm() {}
};
/*
* Interface for a decompression algorithm.
*/
class BOTAN_DLL Decompression_Algorithm
{
public:
/**
* Begin decompressing.
* Decompression does not support levels, as compression does.
*/
virtual void start() = 0;
/**
* Process some data. Input must be in size update_granularity() byte blocks.
* @param buf in/out parameter which will possibly be resized or swapped
* @param offset an offset into blocks to begin processing
*/
virtual void update(secure_vector<byte>& buf, size_t offset = 0) = 0;
/**
* Finish decompressing
*
* @param final_block in/out parameter
* @param offset an offset into final_block to begin processing
*/
virtual void finish(secure_vector<byte>& final_block, size_t offset = 0) = 0;
/**
* @return name of the decompression algorithm
*/
virtual std::string name() const = 0;
/**
* Reset the state and abort the current message; start can be
* called again to process a new message.
*/
virtual void clear() = 0;
virtual ~Decompression_Algorithm() {}
};
BOTAN_DLL Compression_Algorithm* make_compressor(const std::string& type);
BOTAN_DLL Decompression_Algorithm* make_decompressor(const std::string& type);
/**
* Adapts a zlib style API
*/
class Compression_Stream
{
public:
virtual ~Compression_Stream() {}
virtual void next_in(byte* b, size_t len) = 0;
virtual void next_out(byte* b, size_t len) = 0;
virtual size_t avail_in() const = 0;
virtual size_t avail_out() const = 0;
virtual u32bit run_flag() const = 0;
virtual u32bit flush_flag() const = 0;
virtual u32bit finish_flag() const = 0;
virtual bool run(u32bit flags) = 0;
};
/**
* Used to implement compression using Compression_Stream
*/
class Stream_Compression : public Compression_Algorithm
{
public:
void update(secure_vector<byte>& buf, size_t offset, bool flush) final override;
void finish(secure_vector<byte>& buf, size_t offset) final override;
void clear() final override;
private:
void start(size_t level) final override;
void process(secure_vector<byte>& buf, size_t offset, u32bit flags);
virtual Compression_Stream* make_stream(size_t level) const = 0;
secure_vector<byte> m_buffer;
std::unique_ptr<Compression_Stream> m_stream;
};
/**
* FIXME add doc
*/
class Stream_Decompression : public Decompression_Algorithm
{
public:
void update(secure_vector<byte>& buf, size_t offset) final override;
void finish(secure_vector<byte>& buf, size_t offset) final override;
void clear() final override;
private:
void start() final override;
void process(secure_vector<byte>& buf, size_t offset, u32bit flags);
virtual Compression_Stream* make_stream() const = 0;
secure_vector<byte> m_buffer;
std::unique_ptr<Compression_Stream> m_stream;
};
}
#endif
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