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.pc/delete2/generic_file.hpp
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 // $Id$
00022 //
00023 /*********************************************************************/
00024 
00025 #ifndef GENERIC_FILE_HPP
00026 #define GENERIC_FILE_HPP
00027 
00028 #pragma interface
00029 
00030 #include <unistd.h>
00031 #include "infinint.hpp"
00032 #include "path.hpp"
00033 #include "integers.hpp"
00034 
00035 #define CRC_SIZE 2
00036 typedef char crc[CRC_SIZE];
00037 extern void clear(crc & value);
00038 extern void copy_crc(crc & dst, const crc & src);
00039 extern bool same_crc(const crc &a, const crc &b);
00040 
00041 enum gf_mode { gf_read_only, gf_write_only, gf_read_write };
00042 
00043 // note :
00044 // the read and write method are similar to the read and write system call
00045 // except that they never return negative values, but throw exception instead
00046 // returning zero means end of generic_file, and the call is blocking if
00047 // no data is available
00048 // write returns the number of bytes written, and never make partial writtingss
00049 // this it is blocked until all bytes are written or occures an exception
00050 // thus the returned value is always the value of the size argument.
00051 
00052 extern gf_mode generic_file_get_mode(S_I fd);
00053 extern const string generic_file_get_name(gf_mode mode);
00054 
00055 class generic_file
00056 {
00057 public :
00058     generic_file(gf_mode m) { rw = m; clear(value); crc_offset = 0; enable_crc(false); };
00059     virtual ~generic_file() {};
00060     
00061     gf_mode get_mode() const { return rw; };
00062     S_I read(char *a, size_t size);
00063     S_I write(char *a, size_t size);
00064     S_I read_back(char &a);
00065     virtual bool skip(const infinint & pos) = 0;
00066     virtual bool skip_to_eof() = 0;
00067     virtual bool skip_relative(S_I x) = 0;
00068     virtual infinint get_position() = 0;
00069     
00070     void copy_to(generic_file &ref);
00071     void copy_to(generic_file &ref, crc & value);
00072         // generates CRC on copied data
00073     U_32 copy_to(generic_file &ref, U_32 size); // returns the number of byte effectively copied
00074     infinint copy_to(generic_file &ref, infinint size); // returns the number of byte effectively copied
00075     bool diff(generic_file & f); // return true if arg differs from "this"
00076 
00077         // CRC on read or writen data
00078     void reset_crc();
00079     void get_crc(crc & val) { enable_crc(false); copy_crc(val, value); };
00080 
00081 protected :
00082     void set_mode(gf_mode x) { rw = x; };
00083     virtual S_I inherited_read(char *a, size_t size) = 0;
00084         // must provide as much byte as requested up to end of file
00085         // stay blocked if not enough available
00086         // returning zero or less than requested means end of file
00087     virtual S_I inherited_write(char *a, size_t size) = 0;
00088         // must write all data or block or throw exceptions
00089         // thus always returns the second argument
00090 
00091 private :
00092     gf_mode rw;
00093     crc value;
00094     S_I crc_offset;
00095     S_I (generic_file::* active_read)(char *a, size_t size);
00096     S_I (generic_file::* active_write)(char *a, size_t size);
00097 
00098     void enable_crc(bool mode);
00099     void compute_crc(char *a, S_I size);
00100     S_I read_crc(char *a, size_t size);
00101     S_I write_crc(char *a, size_t size);
00102 };
00103 
00104 class fichier : public generic_file
00105 {
00106 public :
00107     fichier(S_I fd);
00108     fichier(char *name, gf_mode m);
00109     fichier(const path & chemin, gf_mode m);
00110     ~fichier() { close(filedesc); };
00111 
00112     infinint get_size() const;
00113 
00114         // herite de generic_file
00115     bool skip(const infinint & pos);
00116     bool skip_to_eof();
00117     bool skip_relative(S_I x);
00118     infinint get_position();
00119 
00120 protected :
00121     S_I inherited_read(char *a, size_t size);
00122     S_I inherited_write(char *a, size_t size);
00123 
00124 private :
00125     S_I filedesc;
00126 
00127     void open(const char *name, gf_mode m);
00128 };
00129 
00130 #endif
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