this is a partial implementation of the generic_file interface to cypher/decypher data block by block. More...

#include <tronconneuse.hpp>

Inherits libdar::proto_tronco.

Collaboration diagram for libdar::tronconneuse:

Public Member Functions
	tronconneuse (U_32 block_size, generic_file &encrypted_side, const archive_version &reading_ver, std::unique_ptr< crypto_module > &ptr)
	This is the constructor. More...

	tronconneuse (const tronconneuse &ref)
	copy constructor

	tronconneuse (tronconneuse &&ref) noexcept
	move constructor

tronconneuse &	operator= (const tronconneuse &ref)
	assignment operator

tronconneuse &	operator= (tronconneuse &&ref) noexcept
	move operator

virtual	~tronconneuse () noexcept override
	destructor

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
	inherited from generic_file

virtual void	write_end_of_file () override
	in write_only mode indicate that end of file is reached More...

virtual void	set_initial_shift (const infinint &x) override
	this method to modify the initial shift. This overrides the constructor "no_initial_shift" of the constructor

virtual void	set_callback_trailing_clear_data (trailing_clear_data_callback callback) override

virtual U_32	get_clear_block_size () const override
	returns the block size give to constructor

Protected Member Functions
const archive_version &	get_reading_version () const

Private Member Functions
virtual void	inherited_read_ahead (const infinint &amount) override
	inherited from generic_file More...

virtual U_I	inherited_read (char *a, U_I size) override
	this protected inherited method is now private for inherited classes of tronconneuse

virtual void	inherited_write (const char *a, U_I size) override
	inherited from generic_file More...

virtual void	inherited_truncate (const infinint &pos) override
	this prorected inherited method is now private for inherited classed of tronconneuse

virtual void	inherited_sync_write () override
	this protected inherited method is now private for inherited classes of tronconneuse

virtual void	inherited_flush_read () override
	this protected inherited method is now private for inherited classes of tronconneuse

virtual void	inherited_terminate () override
	this protected inherited method is now private for inherited classes of tronconneuse

void	nullifyptr () noexcept

void	detruit () noexcept

void	copy_from (const tronconneuse &ref)

void	move_from (tronconneuse &&ref) noexcept

U_32	fill_buf ()
	returns the position (of the next read op) inside the buffer and fill the buffer with clear data

void	flush ()
	flush any pending data (write mode only) to encrypted device

void	init_buf ()
	initialize if necessary the various buffers that relies on inherited method values

void	position_clear2crypt (const infinint &pos, infinint &file_buf_start, infinint &clear_buf_start, infinint &pos_in_buf, infinint &block_num)
	convert clear position to corresponding position in the encrypted data More...

void	position_crypt2clear (const infinint &pos, infinint &clear_pos)

bool	check_current_position ()
	return true if a there is a byte of information at the given offset

void	remove_trailing_clear_data_from_encrypted_buf (const infinint &crypt_offset)

Private Attributes
infinint	initial_shift
	the initial_shift first bytes of the underlying file are not encrypted

infinint	buf_offset
	offset of the first byte in buf

U_32	buf_byte_data
	number of byte of information in buf (buf_byte_data <= buf_size)

U_32	buf_size
	size of allocated memory for clear data in buf

char *	buf
	decrypted data (or data to encrypt)

U_32	clear_block_size
	max amount of data that will be encrypted at once (must stay less than buf_size)

infinint	current_position
	position of the next character to read or write from the upper layer perspective, offset zero is the first encrypted byte, thus the first byte after initial_shift

infinint	block_num
	block number we next read or write

generic_file *	encrypted
	generic_file where is put / get the encrypted data

U_32	encrypted_buf_size
	allocated size of encrypted_buf

U_32	encrypted_buf_data
	amount of byte of information in encrypted_buf

char *	encrypted_buf
	buffer of encrypted data (read or to write)

infinint	extra_buf_offset
	offset of the first byte of extra_buf

U_32	extra_buf_size
	allocated size of extra_buf

U_32	extra_buf_data
	amount of byte of information in extra_buf

char *	extra_buf
	additional read encrypted that follow what is in encrypted_buf used to check for clear data after encrypted data

bool	weof
	whether write_end_of_file() has been called

bool	reof
	whether we reached eof while reading

archive_version	reading_ver
	archive format we currently read

std::unique_ptr< crypto_module >	crypto
	wraps the per block encryption/decryption routines

trailing_clear_data_callback	trailing_clear_data
	callback function that gives the amount of clear data found at the end of the given file

Detailed Description

this is a partial implementation of the generic_file interface to cypher/decypher data block by block.

tronconneuse is either read_only or write_only, read_write is not allowed. The openning mode is defined by encrypted_side's mode. In write_only no skip() is allowed, writing is sequential from the beginning of the file to the end (like writing to a pipe). In read_only all skip() functions are available.

Definition at line 53 of file tronconneuse.hpp.

Constructor & Destructor Documentation

◆ tronconneuse()

libdar::tronconneuse::tronconneuse	(	U_32	block_size,
		generic_file &	encrypted_side,
		const archive_version &	reading_ver,
		std::unique_ptr< crypto_module > &	ptr
	)

This is the constructor.

Parameters

[in]	block_size	is the size of block encryption (the size of clear data encrypted together).
[in]	encrypted_side	where encrypted data are read from or written to.
[in]	reading_ver	version of the archive format
[in]	ptr	pointer to a crypto_module object that will be passed to the tronconneuse object

Note: that encrypted_side is not owned and destroyed by tronconneuse, it must exist during all the life of the tronconneuse object, and is not destroyed by the tronconneuse's destructor

Member Function Documentation

◆ inherited_read_ahead()

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

overrideprivatevirtual

inherited from generic_file

this protected inherited method is now private for inherited classes of tronconneuse

Implements libdar::generic_file.

◆ inherited_write()

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

overrideprivatevirtual

inherited from generic_file

this protected inherited method is now private for inherited classes of tronconneuse

Implements libdar::generic_file.

◆ position_clear2crypt()

void libdar::tronconneuse::position_clear2crypt	(	const infinint &	pos,
		infinint &	file_buf_start,
		infinint &	clear_buf_start,
		infinint &	pos_in_buf,
		infinint &	block_num
	)

private

convert clear position to corresponding position in the encrypted data

Parameters

[in]	pos	is the position in the clear data
[out]	file_buf_start	is the position of the beginning of the crypted block where can be found the data
[out]	clear_buf_start	is the position of the beginning of the corresponding clear block
[out]	pos_in_buf	is the position in the clear block of the 'pos' offset
[out]	block_num	is the block number we have our requested position inside

◆ position_crypt2clear()

void libdar::tronconneuse::position_crypt2clear	(	const infinint &	pos,
		infinint &	clear_pos
	)

private

gives the position of the next character of clear data that corresponds to the encrypted data which index is pos

◆ remove_trailing_clear_data_from_encrypted_buf()

void libdar::tronconneuse::remove_trailing_clear_data_from_encrypted_buf ( const infinint & crypt_offset )

private

remove clear data at the end of the encrypted_buf

Parameters

[in] crypt_offset is the offset of the first byte of encrypted_buf not considering initial_shift bytes before the begining of the encrypted data

◆ set_callback_trailing_clear_data()

virtual void libdar::tronconneuse::set_callback_trailing_clear_data ( trailing_clear_data_callback callback )

inlineoverridevirtual

let the caller give a callback function that given a generic_file with cyphered data, is able to return the offset of the first clear byte located after all the cyphered data, this callback function is used (if defined by the following method), when reaching End of File.

Definition at line 113 of file tronconneuse.hpp.

References trailing_clear_data.

◆ write_end_of_file()

virtual void libdar::tronconneuse::write_end_of_file ( )

inlineoverridevirtual

in write_only mode indicate that end of file is reached

this call must be called in write mode to purge the internal cache before deleting the object (else some data may be lost) no further write call is allowed

Note: this call cannot be used from the destructor, because it relies on pure virtual methods

Definition at line 103 of file tronconneuse.hpp.

References libdar::generic_file::is_terminated().

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

tronconneuse.hpp

Public Member Functions

Protected Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ tronconneuse()

Member Function Documentation

◆ inherited_read_ahead()

◆ inherited_write()

◆ position_clear2crypt()

◆ position_crypt2clear()

◆ remove_trailing_clear_data_from_encrypted_buf()

◆ set_callback_trailing_clear_data()

◆ write_end_of_file()