Disk ARchive 2.3.12
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
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