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storage.hpp
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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
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13 // GNU General Public License for more details.
14 //
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17 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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19 // to contact the author : http://dar.linux.free.fr/email.html
20 /*********************************************************************/
21 
25 
26 #include "../my_config.h"
27 #include "erreurs.hpp"
28 #include "integers.hpp"
29 #include "special_alloc.hpp"
30 
31 #ifdef LIBDAR_MODE
32 #include "infinint.hpp"
33 #endif
34 
35  // it is necessary to not protect the previous inclusion inside
36  // the STORAGE_HPP protection to avoid cyclic dependancies.
37 
38 #ifndef STORAGE_HPP
39 #define STORAGE_HPP
40 
41 #ifndef LIBDAR_MODE
42 namespace libdar
43 {
44  class infinint;
45 }
46 #endif
47 
48 namespace libdar
49 {
50  class generic_file;
51 
53 
56 
57  class storage
58  {
59  private:
60  struct cellule
61  {
62  cellule() : next(NULL), prev(NULL), data(NULL), size(0) {};
63  struct cellule *next, *prev;
64  unsigned char *data;
65  U_32 size;
66  };
67 
68  public:
69  storage(U_32 size)
70  { make_alloc(size, first, last); };
71  storage(const infinint & size);
72  storage(const storage & ref)
73  { copy_from(ref); };
74  storage(generic_file & f, const infinint &size);
75  ~storage()
76  { detruit(first); };
77 
78  const storage & operator = (const storage & val)
79  { detruit(first); copy_from(val); return *this; };
80 
81  bool operator < (const storage & ref) const
82  { return difference(ref) < 0; }; // true if arg uses more space than this
83  bool operator == (const storage & ref) const
84  { return difference(ref) == 0; }; //true if arg have same space than this
85  bool operator > (const storage & ref) const
86  { return difference(ref) > 0; };
87  bool operator <= (const storage & ref) const
88  { return difference(ref) <= 0; };
89  bool operator >= (const storage & ref) const
90  { return difference(ref) >= 0; };
91  bool operator != (const storage & ref) const
92  { return difference(ref) != 0; };
93  unsigned char & operator [](infinint position);
94  unsigned char operator [](const infinint & position) const;
95  infinint size() const;
96  void clear(unsigned char val = 0);
97  void dump(generic_file & f) const;
98 
99  class iterator
100  {
101  public :
102  iterator() : ref(NULL), cell(NULL), offset(0) {};
103  // default constructor by reference is OK
104  // default destructor is OK
105  // default operator = is OK
106 
107  iterator operator ++ (S_I x)
108  { iterator ret = *this; skip_plus_one(); return ret; };
109  iterator operator -- (S_I x)
110  { iterator ret = *this; skip_less_one(); return ret; };
111  iterator & operator ++ ()
112  { skip_plus_one(); return *this; };
113  iterator & operator -- ()
114  { skip_less_one(); return *this; };
115  iterator operator + (U_32 s) const
116  { iterator ret = *this; ret += s; return ret; };
117  iterator operator - (U_32 s) const
118  { iterator ret = *this; ret -= s; return ret; };
119  iterator & operator += (U_32 s);
120  iterator & operator -= (U_32 s);
121  unsigned char &operator *() const;
122 
123  void skip_to(const storage & st, infinint val); // absolute position in st
124  infinint get_position() const;
125 
126  bool operator == (const iterator & cmp) const
127  { return ref == cmp.ref && cell == cmp.cell && offset == cmp.offset; };
128  bool operator != (const iterator & cmp) const
129  { return ! (*this == cmp); };
130 
131  private:
132  static const U_32 OFF_BEGIN = 1;
133  static const U_32 OFF_END = 2;
134 
135  const storage *ref;
136  struct cellule *cell;
137  U_32 offset;
138 
139  void relative_skip_to(S_32 val);
140  bool points_on_data() const
141  { return ref != NULL && cell != NULL && offset < cell->size; };
142 
143  inline void skip_plus_one();
144  inline void skip_less_one();
145 
146  friend class storage;
147  };
148 
149  // public storage methode using iterator
150 
151  iterator begin() const
152  { iterator ret; ret.cell = first; if(ret.cell != NULL) ret.offset = 0; else ret.offset = iterator::OFF_END; ret.ref = this; return ret; };
153  iterator end() const
154  { iterator ret; ret.cell = NULL; ret.offset = iterator::OFF_END; ret.ref = this; return ret; };
155 
156  // WARNING for the two following methods :
157  // there is no "reverse_iterator" type, unlike the standart lib,
158  // thus when going from rbegin() to rend(), you must use the -- operator
159  // unlike the stdlib, that uses the ++ operator. this is the only difference in use with stdlib.
160  iterator rbegin() const
161  { iterator ret; ret.cell = last; ret.offset = last != NULL ? last->size-1 : 0; ret.ref = this; return ret; };
162  iterator rend() const
163  { iterator ret; ret.cell = NULL, ret.offset = iterator::OFF_BEGIN; ret.ref = this; return ret; };
164 
166 
170  U_I write(iterator & it, unsigned char *a, U_I size);
171  U_I read(iterator & it, unsigned char *a, U_I size) const;
172  bool write(iterator & it, unsigned char a)
173  { return write(it, &a, 1) == 1; };
174  bool read(iterator & it, unsigned char &a) const
175  { return read(it, &a, 1) == 1; };
176 
177  // after one of these 3 calls, the iterator given in argument are undefined (they may point nowhere)
178  void insert_null_bytes_at_iterator(iterator it, U_I size);
179  void insert_const_bytes_at_iterator(iterator it, unsigned char a, U_I size);
180  void insert_bytes_at_iterator(iterator it, unsigned char *a, U_I size);
181  void insert_as_much_as_necessary_const_byte_to_be_as_wider_as(const storage & ref, const iterator & it, unsigned char value);
182  void remove_bytes_at_iterator(iterator it, U_I number);
183  void remove_bytes_at_iterator(iterator it, infinint number);
184 
185 #ifdef LIBDAR_SPECIAL_ALLOC
186  USE_SPECIAL_ALLOC(storage);
187 #endif
188  private:
189  struct cellule *first, *last;
190 
191  void copy_from(const storage & ref);
192  S_32 difference(const storage & ref) const;
193  void reduce(); // heuristic that tries to free some memory;
194  void insert_bytes_at_iterator_cmn(iterator it, bool constant, unsigned char *a, U_I size);
195  void fusionne(struct cellule *a_first, struct cellule *a_last, struct cellule *b_first, struct cellule *b_last,
196  struct cellule *&res_first, struct cellule * & res_last);
197 
199  // STATIC statments :
200  //
201 
202  static void detruit(struct cellule *c);
203  static void make_alloc(U_32 size, struct cellule * & begin, struct cellule * & end);
204  static void make_alloc(infinint size, cellule * & begin, struct cellule * & end);
205 
206  friend class storage::iterator;
207  };
208 
209  inline void storage::iterator::skip_plus_one()
210  {
211  if(cell != NULL)
212  if(++offset >= cell->size)
213  {
214  cell = cell->next;
215  if(cell != NULL)
216  offset = 0;
217  else
218  offset = OFF_END;
219  }
220  }
221 
222  inline void storage::iterator::skip_less_one()
223  {
224  if(cell != NULL)
225  {
226  if(offset > 0)
227  --offset;
228  else
229  {
230  cell = cell->prev;
231  if(cell != NULL)
232  offset = cell->size - 1;
233  else
234  offset = OFF_BEGIN;
235  }
236  }
237  }
238 
239 } // end of namespace
240 
241 #endif