Disk ARchive  2.7.0
Full featured and portable backup and archiving tool
escape.hpp
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2 // dar - disk archive - a backup/restoration program
3 // Copyright (C) 2002-2021 Denis Corbin
4 //
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9 //
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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 bool truncatable(const infinint & pos) const override { return x_below->truncatable(pos); };
144  virtual infinint get_position() const override;
145 
146  protected:
147  virtual void inherited_read_ahead(const infinint & amount) override;
148  virtual U_I inherited_read(char *a, U_I size) override;
149  virtual void inherited_write(const char *a, U_I size) override;
150  virtual void inherited_truncate(const infinint & pos) override;
151  virtual void inherited_sync_write() override { flush_write(); };
152  virtual void inherited_flush_read() override { flush_write(); clean_read(); };
153  virtual void inherited_terminate() override { flush_or_clean(); };
154 
155  void change_fixed_escape_sequence(unsigned char value) { fixed_sequence[0] = value; };
156  bool has_escaped_data_since_last_skip() const { return escaped_data_count_since_last_skip > 0; };
157 
158  private:
159 
160  //-- constants
161 
163  static constexpr U_I ESCAPE_SEQUENCE_LENGTH = 6;
164  static constexpr U_I INITIAL_WRITE_BUFFER_SIZE = 2*ESCAPE_SEQUENCE_LENGTH;
165  static constexpr U_I INITIAL_READ_BUFFER_SIZE = MAX_BUFFER_SIZE;
166  static const infinint READ_BUFFER_SIZE_INFININT;
167 
169 
175  static const unsigned char usual_fixed_sequence[ESCAPE_SEQUENCE_LENGTH];
176 
177  //-- variables
178 
179  generic_file *x_below;
180  U_I write_buffer_size;
181  char write_buffer[INITIAL_WRITE_BUFFER_SIZE];
183  U_I already_read;
184  bool read_eof;
185  U_I escape_seq_offset_in_buffer;
186  char* read_buffer;
187  U_I read_buffer_size;
188  U_I read_buffer_alloc;
189  std::set<sequence_type> unjumpable;
190  unsigned char fixed_sequence[ESCAPE_SEQUENCE_LENGTH];
191  infinint escaped_data_count_since_last_skip;
192  infinint below_position;
193 
194  //-- routines
195 
196  void set_fixed_sequence_for(sequence_type t) { fixed_sequence[ESCAPE_SEQUENCE_LENGTH - 1] = type2char(t); };
197  void check_below() const { if(x_below == nullptr) throw SRC_BUG; };
198  void clean_read();
199  void flush_write();
200  void flush_or_clean()
201  {
202  switch(get_mode())
203  {
204  case gf_read_only:
205  clean_read();
206  break;
207  case gf_write_only:
208  case gf_read_write:
209  flush_write();
210  break;
211  default:
212  throw SRC_BUG;
213  }
214  };
215  void nullifyptr() noexcept { x_below = nullptr; };
216  void copy_from(const escape & ref);
217  void move_from(escape && ref) noexcept;
218  bool mini_read_buffer();
219 
220  //-- static routine(s)
221 
222  // some convertion routines
223  static char type2char(sequence_type x);
224  static sequence_type char2type(char x);
225 
227 
229 
232  static U_I trouve_amorce(const char *a, U_I size, const unsigned char escape_sequence[ESCAPE_SEQUENCE_LENGTH]);
233 
235 
242  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]);
243  };
244 
246 
247 } // end of namespace
248 
249 #endif
generic_file(gf_mode m)
main constructor
generic_file & operator=(const generic_file &ref)
assignment operator
bool is_terminated() const
gf_mode get_mode() const
retreive the openning mode for this object
class generic_file is defined here as well as class fichier
@ gf_write_only
write only access
Definition: gf_mode.hpp:46
@ gf_read_only
read only access
Definition: gf_mode.hpp:45
@ gf_read_write
read and write access
Definition: gf_mode.hpp:47
libdar namespace encapsulate all libdar symbols
Definition: archive.hpp:47