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escape.hpp
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1 /*********************************************************************/
2 // dar - disk archive - a backup/restoration program
3 // Copyright (C) 2002-2020 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 //
19 // to contact the author : http://dar.linux.free.fr/email.html
20 /*********************************************************************/
21
37
38
39 #ifndef ESCAPE_HPP
40 #define ESCAPE_HPP
41
42 #include "../my_config.h"
43
44 extern "C"
45 {
46 #if HAVE_LIMITS_H
47 #include <limits.h>
48 #endif
49 }
50
51 #include <set>
52
53 #include "generic_file.hpp"
54
55 #define ESCAPE_FIXED_SEQUENCE_NORMAL 0xAD
56 #define ESCAPE_FIXED_SEQUENCE_SPARSE_FILE 0xAE
57
58 #define MAX_BUFFER_SIZE 102400
59 #ifdef SSIZE_MAX
60 #if SSIZE_MAX < MAX_BUFFER_SIZE
61 #undef MAX_BUFFER_SIZE
62 #define MAX_BUFFER_SIZE SSIZE_MAX
63 #endif
64 #endif
65
66 namespace libdar
67 {
68
71
72 class escape : public generic_file
73 {
74 public:
75 enum sequence_type
76 {
77 seqt_undefined,
78 seqt_not_a_sequence,
79 seqt_file,
80 seqt_ea,
81 seqt_catalogue,
82 seqt_data_name,
83 seqt_file_crc,
84 seqt_ea_crc,
85 seqt_changed,
86 seqt_dirty,
87 seqt_failed_backup,
88 seqt_fsa,
89 seqt_fsa_crc,
90 seqt_delta_sig
91 };
92
93 // the archive layout of marks is for each entry:
94 // #seqt_file# <inode> [<file data> [#seqt_changed# <new copy of data> [...] ] #seqt_file_crc# <CRC>[#seqt_dirty#]] [#seqt_ea# <EA> #seqt_ea_crc# <CRC>]
95 // this previous sequence that we will call <SEQ> is repeated for each file, then on the overall archive we have :
96 // #seqt_data_name# <data_name> <SEQ> ... <SEQ> #seqt_catalogue# <catalogue> <terminator>
97
98 // the provided "below" object must exist during the whole live of the escape object,
99 // the escape object does not own this "below" object
100 // it must be destroyed by the caller/creator of the escape object.
101
102
103 // constructors & destructors
104
105 escape(generic_file *below,
106 const std::set<sequence_type> & x_unjumpable
107 );
108 escape(const escape & ref) : generic_file(ref) { copy_from(ref); };
109 escape(escape && ref) noexcept : generic_file(std::move(ref)) { nullifyptr(); move_from(std::move(ref)); };
110 escape & operator = (const escape & ref);
111 escape & operator = (escape && ref) noexcept { generic_file::operator = (std::move(ref)); move_from(std::move(ref)); return *this; };
112 ~escape();
113
114 // escape specific routines
115
116 void add_mark_at_current_position(sequence_type t);
117
119
124 bool skip_to_next_mark(sequence_type t, bool jump);
125 bool next_to_read_is_mark(sequence_type t);
126 bool next_to_read_is_which_mark(sequence_type & t);
127
128 void add_unjumpable_mark(sequence_type t) { if(is_terminated()) throw SRC_BUG; unjumpable.insert(t); };
129 void remove_unjumpable_mark(sequence_type t);
130 bool is_unjumpable_mark(sequence_type t) const { return unjumpable.find(t) != unjumpable.end(); };
131 void clear_all_unjumpable_marks() { unjumpable.clear(); };
132
133
134 // generic_file inherited routines
135 // NOTA: Nothing is done to prevent skip* operation to put the read cursor in the middle of an escape sequence and
136 // thus incorrectly consider it as normal data. Such event should only occure upon archive corruption and will be detected
137 // by checksum mechanisms.
138
139 virtual bool skippable(skippability direction, const infinint & amount) override;
140 virtual bool skip(const infinint & pos) override;
141 virtual bool skip_to_eof() override;
142 virtual bool skip_relative(S_I x) override;
143 virtual infinint get_position() const override;
144
145 protected:
146 virtual void inherited_read_ahead(const infinint & amount) override;
147 virtual U_I inherited_read(char *a, U_I size) override;
148 virtual void inherited_write(const char *a, U_I size) override;
149 virtual void inherited_sync_write() override { flush_write(); };
150 virtual void inherited_flush_read() override { flush_write(); clean_read(); };
151 virtual void inherited_terminate() override { flush_or_clean(); };
152
153 void change_fixed_escape_sequence(unsigned char value) { fixed_sequence[0] = value; };
154 bool has_escaped_data_since_last_skip() const { return escaped_data_count_since_last_skip > 0; };
155
156 private:
157
158 //-- constants
159
161 static constexpr U_I ESCAPE_SEQUENCE_LENGTH = 6;
162 static constexpr U_I WRITE_BUFFER_SIZE = 2*ESCAPE_SEQUENCE_LENGTH;
163 static constexpr U_I READ_BUFFER_SIZE = MAX_BUFFER_SIZE;
164 static const infinint READ_BUFFER_SIZE_INFININT;
165
167
173 static const unsigned char usual_fixed_sequence[ESCAPE_SEQUENCE_LENGTH];
174
175 //-- variables
176
177 generic_file *x_below;
178 U_I write_buffer_size;
179 char write_buffer[WRITE_BUFFER_SIZE];
180 U_I read_buffer_size;
182 U_I already_read;
183 bool read_eof;
184 U_I escape_seq_offset_in_buffer;
185 char read_buffer[READ_BUFFER_SIZE];
186 std::set<sequence_type> unjumpable;
187 unsigned char fixed_sequence[ESCAPE_SEQUENCE_LENGTH];
188 infinint escaped_data_count_since_last_skip;
189 infinint below_position;
190
191 //-- routines
192
193 void set_fixed_sequence_for(sequence_type t) { fixed_sequence[ESCAPE_SEQUENCE_LENGTH - 1] = type2char(t); };
194 void check_below() const { if(x_below == nullptr) throw SRC_BUG; };
195 void clean_read();
196 void flush_write();
197 void flush_or_clean()
198 {
199 switch(get_mode())
200 {
201 case gf_read_only:
202 clean_read();
203 break;
204 case gf_write_only:
205 case gf_read_write:
206 flush_write();
207 break;
208 default:
209 throw SRC_BUG;
210 }
211 };
212 void nullifyptr() noexcept { x_below = nullptr; };
213 void copy_from(const escape & ref);
214 void move_from(escape && ref) noexcept;
215 bool mini_read_buffer();
216
217 //-- static routine(s)
218
219 // some convertion routines
220 static char type2char(sequence_type x);
221 static sequence_type char2type(char x);
222
224
226
229 static U_I trouve_amorce(const char *a, U_I size, const unsigned char escape_sequence[ESCAPE_SEQUENCE_LENGTH]);
230
232
239 static U_I remove_data_marks_and_stop_at_first_real_mark(char *a, U_I size, U_I & delta, const unsigned char escape_sequence[ESCAPE_SEQUENCE_LENGTH]);
240 };
241
243
244 } // end of namespace
245
246 #endif
libdar::generic_file::generic_file
generic_file(gf_mode m)
main constructor
Definition: generic_file.hpp:80
libdar::generic_file::is_terminated
bool is_terminated() const
Definition: generic_file.hpp:300
libdar::generic_file::get_mode
gf_mode get_mode() const
retreive the openning mode for this object
Definition: generic_file.hpp:109
generic_file.hpp
class generic_file is defined here as well as class fichier
libdar::gf_write_only
@ gf_write_only
write only access
Definition: gf_mode.hpp:46
libdar::gf_read_write
@ gf_read_write
read and write access
Definition: gf_mode.hpp:47
libdar::gf_read_only
@ gf_read_only
read only access
Definition: gf_mode.hpp:45
libdar::generic_file::operator=
generic_file & operator=(const generic_file &ref)
assignment operator
Definition: generic_file.hpp:89
libdar
libdar namespace encapsulate all libdar symbols
Definition: archive.hpp:47