libdar::generic_rsync Class Reference

generic_file interface to librsync More...

#include <generic_rsync.hpp>

Inheritance diagram for libdar::generic_rsync:

Collaboration diagram for libdar::generic_rsync:

Public Member Functions
	generic_rsync (generic_file *signature_storage, U_I signature_block_size, generic_file *below)
	constructor for "signature" operation More...
	generic_rsync (generic_file *base_signature, generic_file *below, const infinint &crc_size, const crc **checksum)
	constructor for "delta" operation More...
	generic_rsync (generic_file *current_data, generic_file *delta)
	constructor for "patch" operation More...
	generic_rsync (const generic_rsync &ref)=delete
	generic_rsync (generic_rsync &&ref) noexcept=delete
generic_rsync &	operator= (const generic_rsync &ref)=delete
generic_rsync &	operator= (generic_rsync &&ref) noexcept=delete
virtual bool	skippable (skippability direction, const infinint &amount) override
	whether the implementation is able to skip More...
virtual bool	skip (const infinint &pos) override
	skip at the absolute position More...
virtual bool	skip_to_eof () override
	skip to the end of file
virtual bool	skip_relative (S_I x) override
	skip relatively to the current position
virtual bool	truncatable (const infinint &pos) const override
	whether the implementation is able to truncate to the given position
virtual infinint	get_position () const override
	get the current read/write position
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
	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) override
	implementation of read() operation More...
virtual void	inherited_write (const char *a, U_I size) override
	implementation of the write() operation More...
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 Types
enum	{ sign , delta , patch }

Private Member Functions
bool	step_forward (const char *buffer_in, U_I &avail_in, bool shift_input, char *buffer_out, U_I &avail_out)
	feed librsync using rs_job_iter More...
void	free_job ()
void	send_eof ()

Private Attributes
enum libdar::generic_rsync:: { ... }	status
generic_file *	x_below
	underlying layer to read from / write to
generic_file *	x_input
generic_file *	x_output
bool	initial
char *	working_buffer
U_I	working_size
bool	patching_completed
crc *	data_crc

Additional Inherited Members
Public Types inherited from libdar::generic_file
enum	skippability { skip_backward , skip_forward }

Detailed Description

generic_file interface to librsync

Definition at line 50 of file generic_rsync.hpp.

Constructor & Destructor Documentation

generic_rsync() [1/3]

libdar::generic_rsync::generic_rsync	(	generic_file *	signature_storage,
		U_I	signature_block_size,
		generic_file *	below
	)

constructor for "signature" operation

in this mode the generic_rsync object is read only, all data read from it is fetched unchanged from "below" while the signature is computed. The file signature is output to signature_storage

Parameters

[in]	signature_storage	is write only mode generic_file
[in]	signature_block_size	the block len to use to build the signature
[in]	below	is read only to fetch data from

generic_rsync() [2/3]

libdar::generic_rsync::generic_rsync	(	generic_file *	base_signature,
		generic_file *	below,
		const infinint &	crc_size,
		const crc **	checksum
	)

constructor for "delta" operation

in this mode the generic_rsync object is also read only, all data read from it is the resulting delta of the data read from "below" based the given base_signature.

Parameters

[in]	base_signature	is read only
[in]	below	is the plain file to read from and for which to compute the delta based on base_signature
[in]	crc_size	is the size of the crc to create if checksum is not nullptr
[in]	checksum	if not null, the *checksum will be set to the address of a newly allocated crc that will receive the calculated crc of the below object, this CRC is calcuated for the data of "below". Caller has the duty to release this object when no more needed but never before this generic_rsync object has been destroyed.

generic_rsync() [3/3]

libdar::generic_rsync::generic_rsync	(	generic_file *	current_data,
		generic_file *	delta
	)

constructor for "patch" operation

in this mode the generic_rsync object is read only, the data read from it is built from the current file's data and the delta signature.

Parameters

[in]	current_data	is a read_only object that contains the data to be used as base for the patch (this data is not modified)
[in]	delta	is read only and contains the patch to apply

Member Function Documentation

inherited_flush_read()

virtual void libdar::generic_rsync::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 116 of file generic_rsync.hpp.

inherited_read()

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

overrideprotectedvirtual

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.

Implements libdar::generic_file.

inherited_read_ahead()

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

inlineoverrideprotectedvirtual

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

Implements libdar::generic_file.

Definition at line 111 of file generic_rsync.hpp.

inherited_sync_write()

virtual void libdar::generic_rsync::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 115 of file generic_rsync.hpp.

inherited_terminate()

virtual void libdar::generic_rsync::inherited_terminate ( )

overrideprotectedvirtual

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.

inherited_truncate()

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

inlineoverrideprotectedvirtual

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.

Definition at line 114 of file generic_rsync.hpp.

References get_position().

inherited_write()

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

overrideprotectedvirtual

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

Implements libdar::generic_file.

skip()

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

inlineoverridevirtual

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

Implements libdar::generic_file.

Definition at line 104 of file generic_rsync.hpp.

skippable()

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

inlineoverridevirtual

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)

Implements libdar::generic_file.

Definition at line 103 of file generic_rsync.hpp.

step_forward()

bool libdar::generic_rsync::step_forward ( const char *  buffer_in, U_I &  avail_in, bool  shift_input, char *  buffer_out, U_I &  avail_out  )

private

feed librsync using rs_job_iter

Parameters

[in]	buffer_in	bytes of data to give to librsync
[in,out]	avail_in	is the amount of byte available, and after the call the amount of not yet read bytes remaining at the beginning of the buffer_in buffer (when shift_input is set to true) or at the end of buffer_in if shift is set to false.
[in]	shift_input
[out]	buffer_out	where to drop the data from librsync
[in,out]	avail_out	is the size of the allocated memory pointed to by buffer_out and after the call the amount of byte that has been dropped to the buffer_out buffer.

Returns

true if librsync returned RS_DONE else false is return if RS_BLOCKED is returned. For any other errors an exception is thrown

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

• generic_rsync.hpp