tronconneuse.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: tronconneuse.hpp,v 1.7.4.1 2007/07/22 16:35:00 edrusb Rel $
00022 //
00023 /*********************************************************************/
00024 //
00025 
00030 
00031 
00032 #ifndef TRONCONNEUSE_HPP
00033 #define TRONCONNEUSE_HPP
00034 
00035 #include "../my_config.h"
00036 #include <string>
00037 
00038 #include "infinint.hpp"
00039 #include "generic_file.hpp"
00040 
00041 namespace libdar
00042 {
00043 
00045 
00058     class tronconneuse : public generic_file
00059     {
00060     public:
00062 
00068         tronconneuse(user_interaction & dialog, U_32 block_size, generic_file & encrypted_side);
00069 
00071         tronconneuse(const tronconneuse & ref) : generic_file(ref) { copy_from(ref); };
00072 
00074         tronconneuse & operator = (const tronconneuse & ref);
00075 
00077         virtual ~tronconneuse() { detruit(); };
00078 
00080         bool skip(const infinint & pos);
00082         bool skip_to_eof();
00084         bool skip_relative(S_I x);
00086         infinint get_position() { return current_position; };
00087 
00089 
00093         void write_end_of_file() { flush(); weof = true; };
00094 
00095     private:
00096 
00098 
00100         S_I inherited_read(char *a, size_t size);
00101 
00103 
00105         S_I inherited_write(const char *a, size_t size);
00106 
00107     protected:
00109 
00115         virtual U_32 encrypted_block_size_for(U_32 clear_block_size) = 0;
00116 
00118 
00125         virtual U_32 clear_block_allocated_size_for(U_32 clear_block_size) = 0;
00126 
00128 
00137         virtual U_32 encrypt_data(const infinint & block_num,
00138                                   const char *clear_buf, const U_32 clear_size, const U_32 clear_allocated,
00139                                   char *crypt_buf, U_32 crypt_size) = 0;
00140 
00142 
00149         virtual U_32 decrypt_data(const infinint & block_num,
00150                                   const char *crypt_buf, const U_32 crypt_size,
00151                                   char *clear_buf, U_32 clear_size) = 0;
00152 
00153 
00154     private:
00155         infinint initial_shift;    // the initial_shift first bytes of the underlying file are not encrypted
00156         infinint buf_offset;       // offset of the first byte in buf
00157         U_32 buf_byte_data;        // number of byte of information in buf (buf_byte_data <= buf_size)
00158         U_32 buf_size;             // size of allocated memory for clear data in buf
00159         char *buf;                 // decrypted data (or data to encrypt)
00160         U_32 clear_block_size;     // max amount of data that will be encrypted (must stay less than buf_size)
00161         infinint current_position; // position of the next character to read or write
00162         infinint block_num;        // block number we next read or write
00163         generic_file *encrypted;   // generic_file where is put / get the encrypted data
00164         char *encrypted_buf;       // buffer of encrypted data (read or to write)
00165         U_32 encrypted_buf_size;   // allocated size of encrypted_buf
00166         bool weof;                 // whether write_end_of_file() has been called
00167 
00168 
00169         void detruit();
00170         void copy_from(const tronconneuse & ref);
00171         U_32 fill_buf();       // returns the position (of the next read) inside the buffer and fill the buffer with clear data
00172         void flush();          // flush any pending data (write mode only) to encrypted device
00173         void init_buf();       // initialize if necessary the various buffers that relies on inherited method values
00174 
00175         void position_clear2crypt(const infinint & pos, infinint & file_buf_start,
00176                                   infinint & clear_buf_start, infinint & pos_in_buf, infinint & block_num);
00177             // pos (input) is the position in the clear data
00178             // file_buf_start (output) is the position of the begining of the crypted block where can be found the data
00179             // file_buf_clear (output) is the position of the beginning of the corresponding clear block
00180             // pos_in_buf (output) is the position in the clear block of the 'pos' offset
00181             // block_num (output) is the block number we have our requested position inside
00182 
00183         void position_crypt2clear(const infinint & pos, infinint & clear_pos);
00184             // gives the position of the next character
00185             // of clear data that corresponds to the encrypted data which index is pos
00186 
00187         bool check_current_position() { return fill_buf() < buf_byte_data; };
00188             // return true if a there is a byte of information at the given offset
00189     };
00190 
00191 
00192 } // end of namespace
00193 
00194 #endif

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