Disk ARchive  2.5.2
Full featured and portable backup and archiving tool
tronc.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 
00028 
00029 #ifndef TRONC_HPP
00030 #define TRONC_HPP
00031 
00032 #include "../my_config.h"
00033 #include "infinint.hpp"
00034 #include "generic_file.hpp"
00035 
00036 namespace libdar
00037 {
00040 
00042 
00043     class tronc : public generic_file
00044     {
00045     public :
00047 
00052         tronc(generic_file *f, const infinint &offset, const infinint &size, bool own_f = false);
00053         tronc(generic_file *f, const infinint &offset, const infinint &size, gf_mode mode, bool own_f = false);
00054 
00057         tronc(generic_file *f, const infinint &offset, bool own_f = false);
00058         tronc(generic_file *f, const infinint &offset, gf_mode mode, bool own_f = false);
00059 
00061     ~tronc()
00062     {
00063         if(own_ref)
00064         delete ref;
00065     };
00066 
00068     void modify(const infinint & new_offset, const infinint & new_size);
00070     void modify(const infinint & new_offset);
00072     void modify() { modify(0); };
00073 
00075     bool skippable(skippability direction, const infinint & amount);
00077         bool skip(const infinint & pos);
00079         bool skip_to_eof();
00081         bool skip_relative(S_I x);
00083         infinint get_position() const { return current; };
00084 
00092     void check_underlying_position_while_reading_or_writing(bool mode) { check_pos = mode ; };
00093 
00094 
00095     protected :
00097     void inherited_read_ahead(const infinint & amount);
00099         U_I inherited_read(char *a, U_I size);
00101         void inherited_write(const char *a, U_I size);
00102     void inherited_sync_write() { ref->sync_write(); }
00103     void inherited_flush_read() {};
00104     void inherited_terminate() {if(own_ref) ref->terminate(); };
00105 
00106     private :
00107         infinint start;    //< offset in the global generic file to start at
00108     infinint sz;       //< length of the portion to consider
00109         generic_file *ref; //< global generic file of which to take a piece
00110         infinint current;  //< inside position of the next read or write
00111     bool own_ref;      //< whether we own ref (and must destroy it when no more needed)
00112     bool limited;      //< whether the sz argument is to be considered
00113     bool check_pos;    //< whether to check and eventually adjust (seek) the position of the underlying layer at each read or write
00114 
00115     void set_back_current_position();
00116     };
00117 
00119 
00120 } // end of namespace
00121 
00122 #endif
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