Disk ARchive  2.4.8
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups
tronconneuse.hpp
Go to the documentation of this file.
1 /*********************************************************************/
2 // dar - disk archive - a backup/restoration program
3 // Copyright (C) 2002-2052 Denis Corbin
4 //
5 // This program is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU General Public License
7 // as published by the Free Software Foundation; either version 2
8 // of the License, or (at your option) any later version.
9 //
10 // This program is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 // GNU General Public License for more details.
14 //
15 // You should have received a copy of the GNU General Public License
16 // along with this program; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 //
19 // to contact the author : http://dar.linux.free.fr/email.html
20 /*********************************************************************/
21 
27 
28 #ifndef TRONCONNEUSE_HPP
29 #define TRONCONNEUSE_HPP
30 
31 #include "../my_config.h"
32 #include <string>
33 
34 #include "infinint.hpp"
35 #include "generic_file.hpp"
36 #include "header_version.hpp"
37 
38 namespace libdar
39 {
40 
43 
44 
46 
59  class tronconneuse : public generic_file
60  {
61  public:
63 
71  tronconneuse(U_32 block_size, generic_file & encrypted_side, bool no_initial_shift, const archive_version & reading_ver);
72 
74  tronconneuse(const tronconneuse & ref) : generic_file(ref) { copy_from(ref); };
75 
77  const tronconneuse & operator = (const tronconneuse & ref);
78 
80  virtual ~tronconneuse() { detruit(); }; // must not write pure virtual method from here, directly or not
81 
83  bool skip(const infinint & pos);
85  bool skip_to_eof();
87  bool skip_relative(S_I x);
89  infinint get_position() { if(is_terminated()) throw SRC_BUG; return current_position; };
90 
92 
97  void write_end_of_file() { if(is_terminated()) throw SRC_BUG; flush(); weof = true; };
98 
99 
101 
102  void set_initial_shift(const infinint & x) { initial_shift = x; };
103 
104 
108  void set_callback_trailing_clear_data(infinint (*call_back)(generic_file & below, const archive_version & reading_ver)) { trailing_clear_data = call_back; };
109 
110  private:
111 
113 
115  U_I inherited_read(char *a, U_I size);
116 
118 
120  void inherited_write(const char *a, U_I size);
121 
123  void inherited_sync_write() { flush(); };
124 
126  void inherited_terminate() {};
127 
128  protected:
130 
136  virtual U_32 encrypted_block_size_for(U_32 clear_block_size) = 0;
137 
139 
146  virtual U_32 clear_block_allocated_size_for(U_32 clear_block_size) = 0;
147 
149 
158  virtual U_32 encrypt_data(const infinint & block_num,
159  const char *clear_buf, const U_32 clear_size, const U_32 clear_allocated,
160  char *crypt_buf, U_32 crypt_size) = 0;
161 
163 
170  virtual U_32 decrypt_data(const infinint & block_num,
171  const char *crypt_buf, const U_32 crypt_size,
172  char *clear_buf, U_32 clear_size) = 0;
173 
174 
175  private:
176  infinint initial_shift; //< the initial_shift first bytes of the underlying file are not encrypted
177  infinint buf_offset; //< offset of the first byte in buf
178  U_32 buf_byte_data; //< number of byte of information in buf (buf_byte_data <= buf_size)
179  U_32 buf_size; //< size of allocated memory for clear data in buf
180  char *buf; //< decrypted data (or data to encrypt)
181  U_32 clear_block_size; //< max amount of data that will be encrypted at once (must stay less than buf_size)
182  infinint current_position; //< position of the next character to read or write
183  infinint block_num; //< block number we next read or write
184  generic_file *encrypted; //< generic_file where is put / get the encrypted data
185  char *encrypted_buf; //< buffer of encrypted data (read or to write)
186  U_32 encrypted_buf_size; //< allocated size of encrypted_buf
187  bool weof; //< whether write_end_of_file() has been called
188  bool reof; //< whether we reached eof while reading
189  archive_version reading_ver;//< archive format we currently read
190  infinint (*trailing_clear_data)(generic_file & below, const archive_version & reading_ver); //< callback function that gives the amount of clear data found at the end of the given file
191 
192 
193  void detruit();
194  void copy_from(const tronconneuse & ref);
195  U_32 fill_buf(); // returns the position (of the next read op) inside the buffer and fill the buffer with clear data
196  void flush(); // flush any pending data (write mode only) to encrypted device
197  void init_buf(); // initialize if necessary the various buffers that relies on inherited method values
198 
199 
201 
207  void position_clear2crypt(const infinint & pos,
208  infinint & file_buf_start,
209  infinint & clear_buf_start,
210  infinint & pos_in_buf,
211  infinint & block_num);
212 
213  void position_crypt2clear(const infinint & pos, infinint & clear_pos);
214  // gives the position of the next character
215  // of clear data that corresponds to the encrypted data which index is pos
216 
217  bool check_current_position() { reof = false; return fill_buf() < buf_byte_data; };
218  // return true if a there is a byte of information at the given offset
219 
220  infinint check_trailing_clear_data();
221  // returns the offset of the first byte of cleared data found after all cyphered data
222  };
223 
225 
226 } // end of namespace
227 
228 #endif