tronc.hpp

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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2024 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 TRONC_HPP
#define TRONC_HPP
 
#include "../my_config.h"
#include "infinint.hpp"
#include "generic_file.hpp"
 
namespace libdar
{
 
 
    class tronc : public generic_file
    {
    public :
 
        tronc(generic_file *f, const infinint &offset, const infinint &size, bool own_f = false);
        tronc(generic_file *f, const infinint &offset, const infinint &size, gf_mode mode, bool own_f = false);
 
        tronc(generic_file *f, const infinint &offset, bool own_f = false);
        tronc(generic_file *f, const infinint &offset, gf_mode mode, bool own_f = false);
 
    tronc(const tronc & ref) = delete;
    tronc(tronc && ref) noexcept = delete;
    tronc & operator = (const tronc & ref) = delete;
    tronc & operator = (tronc && ref) = delete;
 
    ~tronc() { detruit(); };
 
    void modify(const infinint & new_offset, const infinint & new_size);
    void modify(const infinint & new_offset);
    void modify() { modify(0); };
 
    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 { return ref->truncatable(start + pos); };
        virtual infinint get_position() const override { return current; };
 
    void check_underlying_position_while_reading_or_writing(bool mode) { check_pos = mode ; };
 
 
    protected :
    virtual void inherited_read_ahead(const infinint & amount) override;
        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 { ref->sync_write(); }
    virtual void inherited_flush_read() override {};
    virtual void inherited_terminate() override {if(own_ref) ref->terminate(); };
 
    private :
        infinint start;    
    infinint sz;       
        generic_file *ref; 
        infinint current;  
    bool own_ref;      
    bool limited;      
    bool check_pos;    
 
    void set_back_current_position();
    void detruit() noexcept { if(own_ref && ref != nullptr) delete ref; };
    };
 
 
} // end of namespace
 
#endif