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libdar::tronc Class Reference
Private

makes a segment of a generic_file appear like a real generic_file More...

`#include <tronc.hpp>`

Inherits libdar::generic_file.

Inherited by libdar::trontextual.

## Public Member Functions

| tronc (generic_file *f, const infinint &offset, const infinint &size, bool own_f=false)
| constructor
| tronc (generic_file *f, const infinint &offset, const infinint &size, gf_mode mode, bool own_f=false)
| tronc (generic_file *f, const infinint &offset, bool own_f=false)
| tronc (generic_file *f, const infinint &offset, gf_mode mode, bool own_f=false)
| tronc (const tronc &ref)=delete
| tronc (tronc &&ref) noexcept=delete
tronc & | operator= (const tronc &ref)=delete
tronc & | operator= (tronc &&ref)=delete
| ~tronc ()
| destructor
void | modify (const infinint &new_offset, const infinint &new_size)
| modify the tronc object to zoom on another (size limited) portion of the underlying object
void | modify (const infinint &new_offset)
| modify the tronc object to zoom on another (size unlimited) portion of the underlying object
void | modify ()
| modify the tronc object to become transparent and allow unrestricted access to the underlyuing object
virtual bool | skippable (skippability direction, const infinint &amount) override
| inherited from generic_file
virtual bool | skip (const infinint &pos) override
| inherited from generic_file
virtual bool | skip_to_eof () override
| inherited from generic_file
virtual bool | skip_relative (S_I x) override
| inherited from generic_file
virtual bool | truncatable (const infinint &pos) const override
| inherited from generic_file
virtual infinint | get_position () const override
| get the current read/write position
void | check_underlying_position_while_reading_or_writing (bool mode)
Public Member Functions inherited from libdar::generic_file
| generic_file (gf_mode m)
| main constructor
| generic_file (const generic_file &ref)
| copy constructor
| generic_file (generic_file &&ref) noexcept
| move constructor
generic_file & | operator= (const generic_file &ref)
| assignment operator
generic_file & | operator= (generic_file &&ref) noexcept
| move operator
| ~generic_file () noexcept(false)
| virtual destructor,
void | terminate ()
| destructor-like call, except that it is allowed to throw exceptions
bool | operator== (generic_file &ref)
bool | operator!= (generic_file &ref)
gf_mode | get_mode () const
| retreive the openning mode for this object
void | read_ahead (const infinint &amount)
void | ignore_read_ahead (bool mode)
virtual U_I | read (char *a, U_I size) override
| read data from the generic_file inherited from proto_generic_file
virtual void | write (const char *a, U_I size) override
| write data to the generic_file inherited from proto_generic_file
void | write (const std::string &arg)
| write a string to the generic_file
S_I | read_back (char &a)
| skip back one char, read on char and skip back one char
S_I | read_forward (char &a)
| read one char
virtual void | truncate (const infinint &pos)
| truncate file at the given offset
virtual void | copy_to (generic_file &ref)
| copy all data from current position to the object in argument
virtual void | copy_to (generic_file &ref, const infinint &crc_size, crc *&value)
| copy all data from the current position to the object in argument and computes a CRC value of the transmitted data
U_32 | copy_to (generic_file &ref, U_32 size)
| small copy (up to 4GB) with CRC calculation
infinint | copy_to (generic_file &ref, infinint size)
| copy the given amount to the object in argument
bool | diff (generic_file &f, const infinint &me_read_ahead, const infinint &you_read_ahead, const infinint &crc_size, crc *&value)
| compares the contents with the object in argument
bool | diff (generic_file &f, const infinint &me_read_ahead, const infinint &you_read_ahead, const infinint &crc_size, crc *&value, infinint &err_offset)
void | reset_crc (const infinint &width)
| reset CRC on read or writen data
bool | crc_status () const
| to known whether CRC calculation is activated or not
crc * | get_crc ()
| get CRC of the transfered date since last reset
void | sync_write ()
| write any pending data
void | flush_read ()
| be ready to read at current position, reseting all pending data for reading, cached and in compression engine for example
Public Member Functions inherited from libdar::proto_generic_file
| proto_generic_file (const proto_generic_file &ref)=default
| copy constructor
| proto_generic_file (proto_generic_file &&ref) noexcept=default
| move constructor
proto_generic_file & | operator= (const proto_generic_file &ref)=default
| assignment operator
proto_generic_file & | operator= (proto_generic_file &&ref) noexcept=default
| move operator
virtual | ~proto_generic_file () noexcept(false)
| virtual destructor

## Protected Member Functions

virtual void | inherited_read_ahead (const infinint &amount) override
| inherited from generic_file
virtual U_I | inherited_read (char *a, U_I size) override
| inherited from generic_file
virtual void | inherited_write (const char *a, U_I size) override
| inherited from generic_file
virtual void | inherited_truncate (const infinint &pos) override
| truncate file at the give offset
virtual void | inherited_sync_write () override
| write down any pending data
virtual void | inherited_flush_read () override
| reset internal engine, flush caches in order to read the data at current position
virtual void | inherited_terminate () override
| destructor-like call, except that it is allowed to throw exceptions
Protected Member Functions inherited from libdar::generic_file
void | set_mode (gf_mode x)
bool | is_terminated () const

## Private Member Functions

void | set_back_current_position ()
void | detruit () noexcept

## Private Attributes

infinint | start
| offset in the global generic file to start at
infinint | sz
| length of the portion to consider
generic_file * | ref
| global generic file of which to take a piece
infinint | current
| inside position of the next read or write
bool | own_ref
| whether we own ref (and must destroy it when no more needed)
bool | limited
| whether the sz argument is to be considered
bool | check_pos
| whether to check and eventually adjust (seek) the position of the underlying layer at each read or write

## Additional Inherited Members

Public Types inherited from libdar::generic_file
enum | skippability { skip_backward , skip_forward }

## Detailed Description

makes a segment of a generic_file appear like a real generic_file

Definition at line 43 of file tronc.hpp.

## Constructor & Destructor Documentation

## tronc() [1/2]

libdar::tronc::tronc | ( | generic_file * | f,
|  | const infinint & | offset,
|  | const infinint & | size,
|  | bool | own_f = `false`
| ) |  |

constructor

Parameters

  f | is the file to take the segment from
  offset | is the position of the beginning of the segment
  size | is the size of the segment
  own_f | is true if this object has to own and must destroy the 'f' object at tronc's destruction time

## tronc() [2/2]

libdar::tronc::tronc | ( | generic_file * | f,
|  | const infinint & | offset,
|  | bool | own_f = `false`
| ) |  |

other constructor, the end of the segment is the end of the underlying generic_file only data before offset is inaccessible

## ~tronc()

libdar::tronc::~tronc | ( |  | ) |

inline

destructor

Definition at line 66 of file tronc.hpp.

## Member Function Documentation

## check_underlying_position_while_reading_or_writing()

void libdar::tronc::check_underlying_position_while_reading_or_writing | ( | bool | mode | ) |

inline

when a tronc is used over a compressor, it becomes necessary to disable position check

Note
  by default, before each read or write, the tronc object check that the underlying object is at adhoc position in regard to where the cursor is currently in the tronc. Disabling that check let ignore possible position mismatch (which are normal when a compressor is found below) while reading or writing but keep seeking the underlying object to the requested position upon any call to tronc::skip_* familly methods.

Definition at line 94 of file tronc.hpp.

References check_pos.

## detruit()

void libdar::tronc::detruit | ( |  | ) |

inline private noexcept

Definition at line 119 of file tronc.hpp.

## get_position()

virtual infinint libdar::tronc::get_position | ( |  | ) | const

inline override virtual

get the current read/write position

Implements libdar::generic_file.

Definition at line 85 of file tronc.hpp.

References current.

## inherited_flush_read()

virtual void libdar::tronc::inherited_flush_read | ( |  | ) |

inline override protected virtual

reset internal engine, flush caches in order to read the data at current position

Note
  when the object relies on external object or system object to fetch the data from for reading, when a call to (inherited_)flush_read() occurs, the current object must not assume that any previously read data is still valid if it has internal buffers or the like and it should flush them asap. This call must not propagate the flush_read to any other gneric_file object it could rely on

Implements libdar::generic_file.

Definition at line 106 of file tronc.hpp.

## inherited_read()

virtual U_I libdar::tronc::inherited_read | ( | char * | a,
|  | U_I | size
| ) |  |

override protected virtual

inherited from generic_file

Implements libdar::generic_file.

## inherited_read_ahead()

virtual void libdar::tronc::inherited_read_ahead | ( | const infinint & | amount | ) |

override protected virtual

inherited from generic_file

Implements libdar::generic_file.

## inherited_sync_write()

virtual void libdar::tronc::inherited_sync_write | ( |  | ) |

inline override protected virtual

write down any pending data

Note
  called after sanity checks from generic_file::sync_write() this method's role is to write down any data pending for writing in the current object it has not to be propagated to other gneric_file object this object could rely on

Implements libdar::generic_file.

Definition at line 105 of file tronc.hpp.

References ref, and libdar::generic_file::sync_write().

## inherited_terminate()

virtual void libdar::tronc::inherited_terminate | ( |  | ) |

inline override protected virtual

destructor-like call, except that it is allowed to throw exceptions

Note
  this method must never be called directly but using terminate() instead, generic_file class manages it to never be called more than once

Implements libdar::generic_file.

Definition at line 107 of file tronc.hpp.

References own_ref, ref, and libdar::generic_file::terminate().

## inherited_truncate()

virtual void libdar::tronc::inherited_truncate | ( | const infinint & | pos | ) |

override protected virtual

truncate file at the give offset

Note
  if pos is greater than the current file size, this call may do nothing (not even enlarging the file)
  this call should always fail on a read-only generic_file
  implementation must throw exception if truncate is not possible for other reason than read/write access mode

Implements libdar::generic_file.

## inherited_write()

virtual void libdar::tronc::inherited_write | ( | const char * | a,
|  | U_I | size
| ) |  |

override protected virtual

inherited from generic_file

Implements libdar::generic_file.

## modify()

void libdar::tronc::modify | ( |  | ) |

inline

modify the tronc object to become transparent and allow unrestricted access to the underlyuing object

Definition at line 73 of file tronc.hpp.

References modify().

Referenced by modify().

## skip()

virtual bool libdar::tronc::skip | ( | const infinint & | pos | ) |

override virtual

inherited from generic_file

Implements libdar::generic_file.

## skip_relative()

virtual bool libdar::tronc::skip_relative | ( | S_I | x | ) |

override virtual

inherited from generic_file

Implements libdar::generic_file.

## skip_to_eof()

virtual bool libdar::tronc::skip_to_eof | ( |  | ) |

override virtual

inherited from generic_file

Implements libdar::generic_file.

## skippable()

virtual bool libdar::tronc::skippable | ( | skippability | direction,
|  | const infinint & | amount
| ) |  |

override virtual

inherited from generic_file

Implements libdar::generic_file.

## truncatable()

virtual bool libdar::tronc::truncatable | ( | const infinint & | pos | ) | const

inline override virtual

inherited from generic_file

Implements libdar::generic_file.

Definition at line 84 of file tronc.hpp.

References ref, start, and libdar::generic_file::truncatable().

## Member Data Documentation

## check_pos

bool libdar::tronc::check_pos

private

whether to check and eventually adjust (seek) the position of the underlying layer at each read or write

Definition at line 116 of file tronc.hpp.

Referenced by check_underlying_position_while_reading_or_writing().

## current

infinint libdar::tronc::current

private

inside position of the next read or write

Definition at line 113 of file tronc.hpp.

Referenced by get_position().

## limited

bool libdar::tronc::limited

private

whether the sz argument is to be considered

Definition at line 115 of file tronc.hpp.

## own_ref

bool libdar::tronc::own_ref

private

whether we own ref (and must destroy it when no more needed)

Definition at line 114 of file tronc.hpp.

Referenced by inherited_terminate().

## ref

generic_file* libdar::tronc::ref

private

global generic file of which to take a piece

Definition at line 112 of file tronc.hpp.

Referenced by inherited_sync_write(), inherited_terminate(), and truncatable().

## start

infinint libdar::tronc::start

private

offset in the global generic file to start at

Definition at line 110 of file tronc.hpp.

Referenced by truncatable().

## sz

infinint libdar::tronc::sz

private

length of the portion to consider

Definition at line 111 of file tronc.hpp.

The documentation for this class was generated from the following file:

- tronc.hpp