this is the interface class from which all other data transfer classes inherit More...

#include <generic_file.hpp>

Inheritance diagram for libdar::generic_file:

Collaboration diagram for libdar::generic_file:

Public Types
enum	skippability { skip_backward , skip_forward }

Public Member Functions
	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 bool	skippable (skippability direction, const infinint &amount)=0
	whether the implementation is able to skip More...

virtual bool	skip (const infinint &pos)=0
	skip at the absolute position More...

virtual bool	skip_to_eof ()=0
	skip to the end of file

virtual bool	skip_relative (S_I x)=0
	skip relatively to the current position

virtual bool	truncatable (const infinint &pos) const =0
	whether the implementation is able to truncate to the given position

virtual void	truncate (const infinint &pos)
	truncate file at the given offset More...

virtual infinint	get_position () const =0
	get the current read/write position

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
void	set_mode (gf_mode x)

virtual void	inherited_read_ahead (const infinint &amount)=0
	tells the object that several calls to read() will follow to probably obtain at least the given amount of data More...

virtual U_I	inherited_read (char *a, U_I size)=0
	implementation of read() operation More...

virtual void	inherited_write (const char *a, U_I size)=0
	implementation of the write() operation More...

virtual void	inherited_truncate (const infinint &pos)=0
	truncate file at the give offset More...

virtual void	inherited_sync_write ()=0
	write down any pending data More...

virtual void	inherited_flush_read ()=0
	reset internal engine, flush caches in order to read the data at current position More...

virtual void	inherited_terminate ()=0
	destructor-like call, except that it is allowed to throw exceptions More...

bool	is_terminated () const

Private Member Functions
void	enable_crc (bool mode)

U_I	read_crc (char *a, U_I size)

void	write_crc (const char *a, U_I size)

void	destroy ()

void	nullifyptr () noexcept

void	copy_from (const generic_file &ref)

void	move_from (generic_file &&ref) noexcept

Private Attributes
gf_mode	rw

crc *	checksum

bool	terminated

bool	no_read_ahead

U_I(generic_file::*	active_read )(char *a, U_I size)

void(generic_file::*	active_write )(const char *a, U_I size)

Detailed Description

this is the interface class from which all other data transfer classes inherit

it provides mainly read and write operations, skip operations and few other functions.

Note: the read and write method are similar to the read and write system calls except that they never return negative values, but throw exception instead. returning zero means end of generic_file. The call is blocked if no data is available for reading. write returns the number of bytes written, and never make partial writtings. Thus, it is blocked until all bytes are written or occures an exception inconsequences the returned value is always the value of the argument "size".

Definition at line 76 of file generic_file.hpp.

Constructor & Destructor Documentation

◆ ~generic_file()

libdar::generic_file::~generic_file ( )

inlinenoexcept

virtual destructor,

Note: this let inherited destructor to be called even from a generic_file pointer to an inherited class

Definition at line 97 of file generic_file.hpp.

Member Function Documentation

◆ copy_to()

virtual void libdar::generic_file::copy_to	(	generic_file &	ref,
		const infinint &	crc_size,
		crc *&	value
	)

virtual

copy all data from the current position to the object in argument and computes a CRC value of the transmitted data

Parameters

[in]	ref	defines where to copy the data to
[in]	crc_size	tell the width of the crc to compute on the copied data
[out]	value	points to a newly allocated crc object containing the crc value

Note: value has to be deleted by the caller when no more needed

Reimplemented in libdar::pile.

◆ diff() [1/2]

bool libdar::generic_file::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

Parameters

[in]	f	is the file to compare the current object with
[in]	me_read_ahead	is the amount of data to read ahead from "*this" (0 for no limit, up to end of eof)
[in]	you_read_ahead	is the amount of data to read ahead from f (0 for no limit, up to end of file
[in]	crc_size	is the width of the CRC to use for calculation
[out]	value	is the computed checksum, its value can be used for additional testing if this method returns false (no difference between files). The given checksum has to be set to the expected width by the caller.

Returns: true if arg differ from "this"

Note: value has to be deleted by the caller when no more needed; the more simple operator == method may be prefered to diff() when no crc calculation is required

◆ diff() [2/2]

bool libdar::generic_file::diff	(	generic_file &	f,
		const infinint &	me_read_ahead,
		const infinint &	you_read_ahead,
		const infinint &	crc_size,
		crc *&	value,
		infinint &	err_offset
	)

compare the contents with the object in argument, also providing the offset of the first difference met

Parameters

[in]	f	is the file to compare the current object with
[in]	me_read_ahead	is the amount of data to read ahead from "*this" (0 for no limit, up to end of eof)
[in]	you_read_ahead	is the amount of data to read ahead from f (0 for no limit, up to end of file
[in]	crc_size	is the width of the CRC to use for calculation
[out]	value	is the computed checksum, its value can be used for additional
[out]	err_offset	in case of difference, holds the offset of the first difference met testing if this method returns false (no difference between files). The given checksum has to be set to the expected width by the caller.

Returns: true if arg differ from "this", else false is returned and err_offset is set

Note: value has to be deleted by the caller when no more needed; the more simple operator == method may be prefered to diff() when no crc calculation is required

◆ get_crc()

crc* libdar::generic_file::get_crc ( )

get CRC of the transfered date since last reset

Returns: a newly allocated crc object, that the caller has the responsibility to delete

Note: does also ends checksum calculation, which if needed again have to be re-enabled calling reset_crc() method

◆ ignore_read_ahead()

void libdar::generic_file::ignore_read_ahead ( bool mode )

inline

ignore read ahead requests

Parameters

[in] mode if set to true read_ahead requests are ignored: inherited_read_ahead() of the inherited class is not called

Note: read_ahead is useful in multi-thread environement when a slave thread can work in advanced and asynchronously to provide read content to reader thread. However, read_ahead is a waste of CPU cycle for in a single threading model

Definition at line 123 of file generic_file.hpp.

◆ inherited_flush_read()

virtual void libdar::generic_file::inherited_flush_read ( )

protectedpure 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

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

◆ inherited_read()

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

protectedpure virtual

implementation of read() operation

Parameters

[in,out]	a	where to put the data to read
[in]	size	says how much data to read

Returns: the exact amount of data read and put into 'a'

Note: read as much byte as requested, up to end of file stays blocked if not enough data is available and EOF not yet met. May return less data than requested only if EOF as been reached. in other worlds, EOF is reached when returned data is stricly less than the requested data Any problem shall be reported by throwing an exception.

Implemented in libdar::zapette, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::generic_rsync, libdar::fichier_global, libdar::compressor_zstd, libdar::compressor, and libdar::cache.

◆ inherited_read_ahead()

virtual void libdar::generic_file::inherited_read_ahead ( const infinint & amount )

protectedpure virtual

tells the object that several calls to read() will follow to probably obtain at least the given amount of data

Parameters

[in] amount is the maximum expected amount of data that is known to be read

Note: this call may be implemented as a do-nothing call, its presence is only to allow optimization when possible, like in multi-threaded environment

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

◆ inherited_sync_write()

virtual void libdar::generic_file::inherited_sync_write ( )

protectedpure 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

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

◆ inherited_terminate()

virtual void libdar::generic_file::inherited_terminate ( )

protectedpure 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

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

◆ inherited_truncate()

virtual void libdar::generic_file::inherited_truncate ( const infinint & pos )

protectedpure 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

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

◆ inherited_write()

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

protectedpure virtual

implementation of the write() operation

Parameters

[in]	a	what data to write
[in]	size	amount of data to write

Note: must either write all data or report an error by throwing an exception

Implemented in libdar::zapette, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::memory_file, libdar::generic_rsync, libdar::fichier_global, libdar::compressor_zstd, libdar::compressor, libdar::cache, and libdar::null_file.

◆ is_terminated()

bool libdar::generic_file::is_terminated ( ) const

inlineprotected

is some specific call (skip() & Co.) need to be forbidden when the object has been terminated, one can use this call to check the terminated status

Definition at line 327 of file generic_file.hpp.

Referenced by libdar::memory_file::get_position(), libdar::parallel_tronconneuse::get_position(), libdar::tronconneuse::get_position(), libdar::zapette::get_position(), libdar::trivial_sar::skip_to_eof(), libdar::zapette::skip_to_eof(), libdar::parallel_tronconneuse::write_end_of_file(), and libdar::tronconneuse::write_end_of_file().

◆ operator==()

bool libdar::generic_file::operator== ( generic_file & ref )

compaire the object content (implies skipping and reading)

Note: this is a more simple method than diff()

◆ read_ahead()

void libdar::generic_file::read_ahead ( const infinint & amount )

read ahead information

Parameters

[in] amount is the expected amount of data the caller will read, if zero is given the object shall prepare as much as possible data for reading until a skip request, write request or a new read_ahead request

Note: after sanity checks, the protected inherited_read_ahead() method is called

Referenced by libdar::cache_global::inherited_read_ahead(), libdar::compressor::inherited_read_ahead(), libdar::compressor_zstd::inherited_read_ahead(), libdar::hash_fichier::inherited_read_ahead(), libdar::trivial_sar::inherited_read_ahead(), and libdar::tuyau_global::inherited_read_ahead().

◆ reset_crc()

void libdar::generic_file::reset_crc ( const infinint & width )

reset CRC on read or writen data

Parameters

[in] width is the width to use for the CRC

◆ skip()

virtual bool libdar::generic_file::skip ( const infinint & pos )

pure virtual

skip at the absolute position

Parameters

[in] pos the offset in byte where next read/write operation must start

Returns: true if operation was successfull and false if the requested position is not valid (after end of file)

Note: if requested position is not valid the reading/writing cursor must be set to the closest valid position

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

Referenced by libdar::compressor::skip(), libdar::compressor_zstd::skip(), and libdar::generic_to_global_file::skip().

◆ skippable()

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

pure virtual

whether the implementation is able to skip

Note: the capability to skip does not mean that skip_relative() or skip() will succeed, but rather that the inherited class implementation does not by construction forbid the requested skip (like inherited class providing a generic_file interface of an anonymous pipe for example)

Implemented in libdar::zapette, libdar::tuyau_global, libdar::tuyau, libdar::tronconneuse, libdar::tronc, libdar::trivial_sar, libdar::scrambler, libdar::sar, libdar::pile, libdar::parallel_tronconneuse, libdar::null_file, libdar::memory_file, libdar::hash_fichier, libdar::generic_to_global_file, libdar::generic_rsync, libdar::fichier_local, libdar::compressor_zstd, libdar::compressor, libdar::cache_global, and libdar::cache.

Referenced by libdar::compressor::skippable(), libdar::compressor_zstd::skippable(), libdar::generic_to_global_file::skippable(), libdar::trivial_sar::skippable(), and libdar::tuyau_global::skippable().

◆ truncate()

virtual void libdar::generic_file::truncate ( const infinint & pos )

virtual

truncate file at the given offset

Parameters

[in] pos is the offset of the where to cut the file, in other word the pos - 1 will be the last byte of the file (if its size is greater than 1). If pos is greater than EOF the implementation should not enlarge the file and may even no skip the file to its current eof. Though this request is not considered an error implementation can thus do nothing when asked to truncate after EOF.

Note: running this call on a read-only object will always yeld an exception; if current file position is after the point to truncate, implementation has to skip back the current writing offset to the new end of file.; implementation of backward skippability and truncate operation should be coherent: If its not possible to skip backward it should not be possible to truncate the file to this position. If truncate a file to requested position is not possible, it should not be possible to skip backward to that position. This truncatable() with the skip_backward direction should indicate whether the truncate() action will succeed or generate an exception

Referenced by libdar::cache_global::inherited_truncate(), libdar::generic_to_global_file::inherited_truncate(), libdar::trivial_sar::inherited_truncate(), and libdar::tuyau_global::inherited_truncate().

◆ write()

void libdar::generic_file::write ( const std::string & arg )

write a string to the generic_file

Note: throws a exception if not all data could be written as expected

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

generic_file.hpp

Public Types

Public Member Functions

Protected Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ~generic_file()

Member Function Documentation

◆ copy_to()

◆ diff() [1/2]

◆ diff() [2/2]

◆ get_crc()

◆ ignore_read_ahead()

◆ inherited_flush_read()

◆ inherited_read()

◆ inherited_read_ahead()

◆ inherited_sync_write()

◆ inherited_terminate()

◆ inherited_truncate()

◆ inherited_write()

◆ is_terminated()

◆ operator==()

◆ read_ahead()

◆ reset_crc()

◆ skip()

◆ skippable()

◆ truncate()

◆ write()