# null_file.hpp

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    00001 /*********************************************************************/
    00002 // dar - disk archive - a backup/restoration program
    00003 // Copyright (C) 2002-2052 Denis Corbin
    00004 //
    00005 // This program is free software; you can redistribute it and/or
    00006 // modify it under the terms of the GNU General Public License
    00007 // as published by the Free Software Foundation; either version 2
    00008 // of the License, or (at your option) any later version.
    00009 //
    00010 // This program is distributed in the hope that it will be useful,
    00011 // but WITHOUT ANY WARRANTY; without even the implied warranty of
    00012 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00013 // GNU General Public License for more details.
    00014 //
    00015 // You should have received a copy of the GNU General Public License
    00016 // along with this program; if not, write to the Free Software
    00017 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
    00018 //
    00019 // to contact the author : dar.linux@free.fr
    00020 /*********************************************************************/
    00021 // $Id: null_file.hpp,v 1.11.4.1 2007/07/22 16:35:00 edrusb Rel $
    00022 //
    00023 /*********************************************************************/
    00024
    00029
    00030 #ifndef NULL_FILE_HPP
    00031 #define NULL_FILE_HPP
    00032
    00033 #include "../my_config.h"
    00034 #include "generic_file.hpp"
    00035 #include "thread_cancellation.hpp"
    00036
    00037 namespace libdar
    00038 {
    00039
    00041
    00048
    00049     class null_file : public generic_file, public thread_cancellation
    00050     {
    00051     public :
    00052         null_file(user_interaction & dialog, gf_mode m) : generic_file(dialog, m) {};
    00053         bool skip(const infinint &pos) { return pos == 0; };
    00054         bool skip_to_eof() { return true; };
    00055         bool skip_relative(signed int x) { return false; };
    00056         infinint get_position() { return 0; };
    00057
    00058     protected :
    00059         int inherited_read(char *a, size_t size)
    00060         {
    00061 #ifdef MUTEX_WORKS
    00062             check_self_cancellation();
    00063 #endif
    00064             return 0;
    00065         };
    00066
    00067         int inherited_write(const char *a, size_t size)
    00068         {
    00069 #ifdef MUTEX_WORKS
    00070             check_self_cancellation();
    00071 #endif
    00072             return size;
    00073         };
    00074     };
    00075
    00076 } // end of namespace
    00077
    00078 #endif