Disk ARchive  2.5.2
Full featured and portable backup and archiving tool
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 : http://dar.linux.free.fr/email.html
00020 /*********************************************************************/
00021 
00027 
00028 #ifndef NULL_FILE_HPP
00029 #define NULL_FILE_HPP
00030 
00031 #include "../my_config.h"
00032 #include "generic_file.hpp"
00033 #include "thread_cancellation.hpp"
00034 
00035 namespace libdar
00036 {
00037 
00040 
00042 
00049 
00050     class null_file : public generic_file, public thread_cancellation
00051     {
00052     public :
00053         null_file(gf_mode m) : generic_file(m) {};
00054     bool skippable(skippability direction, const infinint & amount) { return true; };
00055         bool skip(const infinint &pos) { return true; };
00056         bool skip_to_eof() { return true; };
00057         bool skip_relative(signed int x) { return false; };
00058         infinint get_position() const { return 0; };
00059 
00060     protected :
00061     void inherited_read_ahead(const infinint & amount) {};
00062 
00063         U_I inherited_read(char *a, U_I size)
00064     {
00065 #ifdef MUTEX_WORKS
00066         check_self_cancellation();
00067 #endif
00068         return 0;
00069     };
00070 
00071         void inherited_write(const char *a, U_I size)
00072     {
00073 #ifdef MUTEX_WORKS
00074         check_self_cancellation();
00075 #endif
00076     };
00077 
00078     void inherited_sync_write() {};
00079     void inherited_flush_read() {};
00080     void inherited_terminate() {};
00081     };
00082 
00084 
00085 } // end of namespace
00086 
00087 #endif
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