block_compressor.hpp

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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2025 Denis Corbin
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// to contact the author, see the AUTHOR file
/*********************************************************************/
 
 
 
#ifndef BLOCK_COMPRESSOR_HPP
#define BLOCK_COMPRESSOR_HPP
 
#include "../my_config.h"
 
#include "infinint.hpp"
#include "crypto_segment.hpp"
#include "heap.hpp"
#include "compress_module.hpp"
#include "proto_compressor.hpp"
 
namespace libdar
{
 
 
 
    class block_compressor: public proto_compressor
    {
    public:
    block_compressor(std::unique_ptr<compress_module> block_zipper,
             generic_file & compressed_side,
             U_I uncompressed_bs = default_uncompressed_block_size);
        // compressed_side is not owned by the object and will remains
            // after the objet destruction
 
    block_compressor(const block_compressor & ref) = delete;
    block_compressor(block_compressor && ref) noexcept = delete;
    block_compressor & operator = (const block_compressor & ref) = delete;
    block_compressor & operator = (block_compressor && ref) noexcept = delete;
    ~block_compressor();
 
        // inherited from proto_compressor
 
    virtual compression get_algo() const override { return suspended? compression::none : zipper->get_algo(); };
    virtual void suspend_compression() override;
    virtual void resume_compression() override;
    virtual bool is_compression_suspended() const override { return suspended; };
 
        // inherited from generic file
 
    virtual bool skippable(skippability direction, const infinint & amount) override;
        virtual bool skip(const infinint & pos) override;
        virtual bool skip_to_eof() override;
        virtual bool skip_relative(S_I x) override;
    virtual bool truncatable(const infinint & pos) const override;
        virtual infinint get_position() const override;
 
    protected :
    virtual void inherited_read_ahead(const infinint & amount) override { compressed->read_ahead(amount); };
        virtual U_I inherited_read(char *a, U_I size) override;
        virtual void inherited_write(const char *a, U_I size) override;
    virtual void inherited_truncate(const infinint & pos) override;
    virtual void inherited_sync_write() override;
    virtual void inherited_flush_read() override { if(get_mode() != gf_write_only) current->reset(); reof = false; };
    virtual void inherited_terminate() override;
 
    private:
    static constexpr const U_I min_uncompressed_block_size = 100;
 
 
        // the local fields
 
    std::unique_ptr<compress_module> zipper;  
    generic_file *compressed;                 
    U_I uncompressed_block_size;              
    bool suspended;                           
    bool need_eof;                            
    std::unique_ptr<crypto_segment> current;  
    bool reof;                                
 
        // private methods
 
    void compress_and_write_current();
    void read_and_uncompress_current();
 
    };
 
 
} // end of namespace
 
 
#endif