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Public Types | Public Member Functions | Protected Member Functions | List of all members
libdar::generic_file Class Referenceabstract
Private

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

`#include <generic_file.hpp>`

Inherits libdar::on_pool.

Inherited by hide_file, libdar::cache, libdar::compressor, libdar::escape, libdar::fichier_global, libdar::generic_thread, libdar::memory_file, libdar::null_file, libdar::pile, libdar::sar, libdar::scrambler, libdar::secu_memory_file, libdar::trivial_sar, libdar::tronc, libdar::tronconneuse, libdar::tuyau, and libdar::zapette.

## 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
virtual | ~generic_file () throw (Ebug)
| virtual destructor, this let inherited destructor to be called even from a generic_file pointer to an inherited class
void | terminate () const
| destructor-like call, except that it is allowed to throw exceptions
const generic_file & | operator= (const generic_file &ref)
| assignment operator
gf_mode | get_mode () const
| retreive the openning mode for this object
virtual void | read_ahead (const infinint &amount)
void | ignore_read_ahead (bool mode)
U_I | read (char *a, U_I size)
| read data from the generic_file More...
void | write (const char *a, U_I size)
| write data to the generic_file More...
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
virtual bool | skip (const infinint &pos)=0
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 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::on_pool
void * | operator new (size_t n_byte)
void * | operator new (size_t n_byte, const std::nothrow_t &nothrow_value)
void * | operator new[] (size_t n_byte)
void * | operator new[] (size_t n_byte, const std::nothrow_t &nothrow_value)
void * | operator new (size_t n_byte, memory_pool *p)
void * | operator new[] (size_t n_byte, memory_pool *p)
void | operator delete (void *ptr, memory_pool *p)
| this operator is called by the compiler if an exception is throw from the constructor of the allocated object
void | operator delete[] (void *ptr, memory_pool *p)
| this operator is called by the compiler if an exception is throw from the constructor of the allocated objects
void | operator delete (void *ptr)
| this is the usual delete operator, modified to handle allocated objects allocated on a memory pool or not
void | operator delete[] (void *ptr)
| this is the usual delete[] operator, modified to handle allocated objects allocated on a memory pool or not

## Protected Member Functions
void | set_mode (gf_mode x)
virtual void | inherited_read_ahead (const infinint &amount)=0
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_sync_write ()=0
| write down any pending data More...
virtual void | inherited_flush_read ()=0
virtual void | inherited_terminate ()=0
| destructor-like call, except that it is allowed to throw exceptions More...
bool | is_terminated () const
Protected Member Functions inherited from libdar::on_pool
memory_pool * | get_pool () const
template<class T >
void | meta_new (T *&ptr, size_t num)
template<class T >
void | meta_delete (T *ptr)

## 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 100 of file generic_file.hpp.

## Member Function Documentation

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

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

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

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

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 134 of file generic_file.hpp.

virtual void libdar::generic_file::inherited_flush_read | ( |  | ) |
| protected pure 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::sar, libdar::trivial_sar, libdar::fichier_local, libdar::tronc, libdar::compressor, libdar::zapette, libdar::tuyau, libdar::null_file, libdar::cache, and libdar::scrambler.

virtual U_I libdar::generic_file::inherited_read | ( | char * | a,
|  | U_I | size
| ) |  |
| protected pure 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::sar, libdar::trivial_sar, libdar::tronc, libdar::compressor, libdar::zapette, libdar::tuyau, libdar::cache, libdar::null_file, and libdar::scrambler.

virtual void libdar::generic_file::inherited_read_ahead | ( | const infinint & | amount | ) |
| protected pure 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::sar, libdar::trivial_sar, libdar::fichier_local, libdar::tronc, libdar::compressor, libdar::zapette, libdar::tuyau, libdar::cache, libdar::null_file, and libdar::scrambler.

virtual void libdar::generic_file::inherited_sync_write | ( |  | ) |
| protected pure 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::sar, libdar::trivial_sar, libdar::fichier_local, libdar::tronc, libdar::compressor, libdar::zapette, libdar::tuyau, libdar::null_file, libdar::cache, and libdar::scrambler.

virtual void libdar::generic_file::inherited_terminate | ( |  | ) |
| protected pure 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::sar, libdar::trivial_sar, libdar::fichier_local, libdar::tronc, libdar::compressor, libdar::zapette, libdar::tuyau, libdar::null_file, libdar::cache, and libdar::scrambler.

virtual void libdar::generic_file::inherited_write | ( | const char * | a,
|  | U_I | size
| ) |  |
| protected pure 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::sar, libdar::trivial_sar, libdar::tronc, libdar::compressor, libdar::zapette, libdar::tuyau, libdar::cache, libdar::null_file, and libdar::scrambler.

bool libdar::generic_file::is_terminated | ( |  | ) | const
| inline protected

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 316 of file generic_file.hpp.

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

U_I libdar::generic_file::read | ( | char * | a,
|  | U_I | size
| ) |  |

read data from the generic_file

Parameters

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

Returns
  the exact number of byte read.

Note
  read as much as requested data, unless EOF is met (only EOF can lead to reading less than requested data)
  EOF is met if read() returns less than size

Referenced by read_forward().

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

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::scrambler::inherited_read_ahead(), libdar::cache::inherited_read_ahead(), libdar::compressor::inherited_read_ahead(), and libdar::trivial_sar::inherited_read_ahead().

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

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::sar, libdar::trivial_sar, libdar::fichier_local, libdar::compressor, libdar::tronconneuse, libdar::tronc, libdar::tuyau, libdar::zapette, libdar::cache, libdar::null_file, and libdar::scrambler.

Referenced by libdar::compressor::skip().

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::sar, libdar::trivial_sar, libdar::fichier_local, libdar::compressor, libdar::tronconneuse, libdar::tuyau, libdar::tronc, libdar::zapette, libdar::cache, libdar::null_file, and libdar::scrambler.

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

void libdar::generic_file::write | ( | const char * | a,
|  | U_I | size
| ) |  |

write data to the generic_file

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

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