libdar::tronc Class Reference

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

#include <tronc.hpp>

Inheritance diagram for libdar::tronc:

Collaboration diagram for libdar::tronc:

Public Member Functions
	tronc (generic_file *f, const infinint &offset, const infinint &size, bool own_f=false)
	constructor More...
	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, More...
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 More...
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 More...
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 More...
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 More...
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 More...
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 More...
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 More...

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 More...
virtual void	inherited_sync_write () override
	write down any pending data More...
virtual void	inherited_flush_read () override
	reset internal engine, flush caches in order to read the data at current position More...
virtual void	inherited_terminate () override
	destructor-like call, except that it is allowed to throw exceptions More...
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

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.

inherited_flush_read()

virtual void libdar::tronc::inherited_flush_read ( )

inlineoverrideprotectedvirtual

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_sync_write()

virtual void libdar::tronc::inherited_sync_write ( )

inlineoverrideprotectedvirtual

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 ( )

inlineoverrideprotectedvirtual

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 )

overrideprotectedvirtual

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.

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

• tronc.hpp