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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 <botan/exceptn.h>
#include <string>
namespace Botan {
/**
* Interface for a compression algorithm.
*/
class BOTAN_PUBLIC_API(2,0) Compression_Algorithm
{
public:
/**
* Create an instance based on a name, or return null if the
* algo combination cannot be found.
*/
static std::unique_ptr<Compression_Algorithm>
create(const std::string& algo_spec);
/**
* Create an instance based on a name
* @param algo_spec algorithm name
* Throws Lookup_Error if not found.
*/
static std::unique_ptr<Compression_Algorithm>
create_or_throw(const std::string& algo_spec);
/**
* 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.
* @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<uint8_t>& 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<uint8_t>& 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() = default;
};
/*
* Interface for a decompression algorithm.
*/
class BOTAN_PUBLIC_API(2,0) Decompression_Algorithm
{
public:
/**
* Create an instance based on a name, or return null if the
* algo combination cannot be found.
*/
static std::unique_ptr<Decompression_Algorithm>
create(const std::string& algo_spec);
/**
* Create an instance based on a name
* @param algo_spec algorithm name
* Throws Lookup_Error if not found.
*/
static std::unique_ptr<Decompression_Algorithm>
create_or_throw(const std::string& algo_spec);
/**
* Begin decompressing.
* Decompression does not support levels, as compression does.
*/
virtual void start() = 0;
/**
* Process some data.
* @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<uint8_t>& 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<uint8_t>& 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() = default;
};
BOTAN_PUBLIC_API(2,0) Compression_Algorithm* make_compressor(const std::string& type);
BOTAN_PUBLIC_API(2,0) Decompression_Algorithm* make_decompressor(const std::string& type);
/**
* An error that occurred during compression (or decompression)
*/
class BOTAN_PUBLIC_API(2,9) Compression_Error : public Exception
{
public:
/**
* @param func_name the name of the compression API that was called
* (eg "BZ2_bzCompressInit" or "lzma_code")
* @param type what library this came from
* @param rc the error return code from the compression API. The
* interpretation of this value will depend on the library.
*/
Compression_Error(const char* func_name, ErrorType type, int rc) :
Exception("Compression API " + std::string(func_name) +
" failed with return code " + std::to_string(rc)),
m_type(type),
m_rc(rc)
{}
ErrorType error_type() const noexcept override { return m_type; }
int error_code() const noexcept override { return m_rc; }
private:
ErrorType m_type;
int m_rc;
};
/**
* Adapts a zlib style API
*/
class Compression_Stream
{
public:
virtual ~Compression_Stream() = default;
virtual void next_in(uint8_t* b, size_t len) = 0;
virtual void next_out(uint8_t* b, size_t len) = 0;
virtual size_t avail_in() const = 0;
virtual size_t avail_out() const = 0;
virtual uint32_t run_flag() const = 0;
virtual uint32_t flush_flag() const = 0;
virtual uint32_t finish_flag() const = 0;
virtual bool run(uint32_t flags) = 0;
};
/**
* Used to implement compression using Compression_Stream
*/
class Stream_Compression : public Compression_Algorithm
{
public:
void update(secure_vector<uint8_t>& buf, size_t offset, bool flush) final override;
void finish(secure_vector<uint8_t>& buf, size_t offset) final override;
void clear() final override;
private:
void start(size_t level) final override;
void process(secure_vector<uint8_t>& buf, size_t offset, uint32_t flags);
virtual Compression_Stream* make_stream(size_t level) const = 0;
secure_vector<uint8_t> m_buffer;
std::unique_ptr<Compression_Stream> m_stream;
};
/**
* FIXME add doc
*/
class Stream_Decompression : public Decompression_Algorithm
{
public:
void update(secure_vector<uint8_t>& buf, size_t offset) final override;
void finish(secure_vector<uint8_t>& buf, size_t offset) final override;
void clear() final override;
private:
void start() final override;
void process(secure_vector<uint8_t>& buf, size_t offset, uint32_t flags);
virtual Compression_Stream* make_stream() const = 0;
secure_vector<uint8_t> m_buffer;
std::unique_ptr<Compression_Stream> m_stream;
};
}
#endif
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