null_file.hpp

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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2052 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// to contact the author : http://dar.linux.free.fr/email.html
/*********************************************************************/


#ifndef NULL_FILE_HPP
#define NULL_FILE_HPP

#include "../my_config.h"
#include "generic_file.hpp"
#include "thread_cancellation.hpp"

namespace libdar
{




    class null_file : public generic_file, public thread_cancellation
    {
    public :
        null_file(gf_mode m) : generic_file(m) {};
        bool skip(const infinint &pos) { return true; };
        bool skip_to_eof() { return true; };
        bool skip_relative(signed int x) { return false; };
        infinint get_position() { return 0; };

#ifdef LIBDAR_SPECIAL_ALLOC
        USE_SPECIAL_ALLOC(null_file);
#endif
    protected :
        U_I inherited_read(char *a, U_I size)
        {
#ifdef MUTEX_WORKS
            check_self_cancellation();
#endif
            return 0;
        };

        void inherited_write(const char *a, U_I size)
        {
#ifdef MUTEX_WORKS
            check_self_cancellation();
#endif
        };

        void inherited_sync_write() {};

        void inherited_terminate() {};
    };


} // end of namespace

#endif