the cat_delta_signature file class More...

#include <cat_delta_signature.hpp>

Public Member Functions
	cat_delta_signature (generic_file f, compressor c)
	constructor to read an object (using read() later on) from filesystem More...

	cat_delta_signature ()
	constructor to write an object to filesytem (using dump_* methods later on)

	cat_delta_signature (const cat_delta_signature &ref)
	copy constructor

	cat_delta_signature (cat_delta_signature &&ref) noexcept
	move constructor

cat_delta_signature &	operator= (const cat_delta_signature &ref)
	assignement operator

cat_delta_signature &	operator= (cat_delta_signature &&ref) noexcept
	move assignment operator

	~cat_delta_signature ()
	destructor

void	read (bool sequential_read)

bool	can_obtain_sig () const
	the cat_delta_signature structure can only hold CRC without delta_signature, this call gives the situation about that point

std::shared_ptr< memory_file >	obtain_sig () const
	provide a memory_file object which the caller has the duty to destroy after use More...

void	drop_sig () const
	drop signature but keep metadata available More...

void	will_have_signature ()
	give the object where to fetch from the delta signature, object must exist up to the next call to dump_data More...

void	set_sig (const std::shared_ptr< memory_file > &ptr)
	the object pointed to by ptr must stay available when calling dump_data()/dump_metadata() later on

void	set_sig ()
	variante used when the delta_signature object will only contain CRCs (no delta signature)

void	dump_data (generic_file &f, bool sequential_mode) const
	write down the data eventually with sequential read mark followed by delta sig metadata

void	dump_metadata (generic_file &f) const
	write down the delta_signature metadata for catalogue

bool	has_patch_base_crc () const
	returns whether the object has a base patch CRC (s_delta status objects)

bool	get_patch_base_crc (const crc *&c) const
	returns the CRC of the file to base the patch on, for s_delta objects

void	set_patch_base_crc (const crc &c)
	set the reference CRC of the file to base the patch on, for s_detla objects

bool	has_patch_result_crc () const
	returns whether the object has a CRC corresponding to data (for s_saved, s_delta, and when delta signature is present)

bool	get_patch_result_crc (const crc *&c) const
	returns the CRC the file will have once restored or patched (for s_saved, s_delta, and when delta signature is present)

void	set_patch_result_crc (const crc &c)
	set the CRC the file will have once restored or patched (for s_saved, s_delta, and when delta signature is present)

void	clear ()
	reset the object

Private Member Functions
void	init () noexcept

void	copy_from (const cat_delta_signature &ref)

void	move_from (cat_delta_signature &&ref) noexcept

void	destroy () noexcept

void	fetch_data () const

Private Attributes
crc *	patch_base_check
	associated CRC for the file this signature has been computed on

infinint	delta_sig_size
	size of the data to setup "sig" (set to zero when reading in sequential mode, sig is then setup on-fly)

infinint	delta_sig_offset
	where to read data from to setup "sig" (set to zero when read in sequential mode, sig is setup on-fly)

std::shared_ptr< memory_file >	sig
	the signature data, if set nullptr it will be fetched from f in direct access mode only

crc *	patch_result_check
	associated CRC

generic_file *	src
	where to read data from

compressor *	zip
	needed to disable compression when reading delta signature data from an archive

Detailed Description

the cat_delta_signature file class

this class works in to implicit modes

read mode read the metadata from an archive the caller having knowing where to find it read the data and fill the provided memory_file (get_sig()) by the delta signature provide access to the associated CRC
write mode stores the associated CRC write down the given delta signature (with metadata in sequential mode) write down the metadata the signature is not stored

Definition at line 90 of file cat_delta_signature.hpp.

Constructor & Destructor Documentation

◆ cat_delta_signature()

libdar::cat_delta_signature::cat_delta_signature	(	generic_file *	f,
		compressor *	c
	)

constructor to read an object (using read() later on) from filesystem

Parameters

[in]	f	where to read the data from, used when calling read() later on. f must not be set to nullptr and the pointed to object must survive this cat_delta_signature object
[in]	c	points to the compressor layer in order to suspend compression when reading data (metadata will be read compressed or not depending on the its location (in-lined or in the catalogue at end of archive)

Member Function Documentation

◆ drop_sig()

void libdar::cat_delta_signature::drop_sig ( ) const

inline

drop signature but keep metadata available

Note: there is a lot of chance that a call to obtain_sig() will fail after drop_sig() has been called when in sequential read mode, due to the limited possibility to skip backward in that mode

Definition at line 141 of file cat_delta_signature.hpp.

References sig.

◆ obtain_sig()

std::shared_ptr<memory_file> libdar::cat_delta_signature::obtain_sig ( ) const

provide a memory_file object which the caller has the duty to destroy after use

Note: while drop_sig has not been called, obtain_sig() can be called any number of time; in direct mode (not sequential_real mode) the first call to obtain_sig() fetches the data from the archive and loads it to memory.

Referenced by can_obtain_sig().

◆ read()

void libdar::cat_delta_signature::read ( bool sequential_read )

read the metadata of the object from the generic_file given at construction time

Note: in sequential read mode, the data is also read at that time and loaded into memory, thing which is done transparently by obtain_sig() when in direct access mode

Referenced by ~cat_delta_signature().

◆ will_have_signature()

void libdar::cat_delta_signature::will_have_signature ( )

inline

give the object where to fetch from the delta signature, object must exist up to the next call to dump_data

Note: seg_sig_ref() must be called each time before invoking dump_data(), normally it is done once... for can_obtain_sig() to return true before the signature is provided

Definition at line 150 of file cat_delta_signature.hpp.

References delta_sig_size, and set_sig().

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

cat_delta_signature.hpp

Public Member Functions

Private Member Functions

Private Attributes