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libdar::generic_file Class Referenceabstract

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

#include <generic_file.hpp>

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

Public Member Functions

 generic_file (gf_mode m)
 main constructor
 
 generic_file (const generic_file &ref)
 copy constructor
 
void terminate () const
 virtual destructor, this let inherited destructor to be called even from a generic_file pointer to an inherited class
 
const generic_fileoperator= (const generic_file &ref)
 assignment operator
 
gf_mode get_mode () const
 retreive the openning mode for this object
 
U_I read (char *a, U_I size)
 read data from the generic_file
 
void write (const char *a, U_I size)
 write data to the generic_file
 
void write (const std::string &arg)
 write a string to the generic_file
 
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 skip (const infinint &pos)=0
 skip at the absolute position
 
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 ()=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, crc &value)
 copy all data from the current position to the object in argument and computes a CRC value of the transmitted data
 
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, crc &value)
 compares the contents with the object in argument
 
void reset_crc (const infinint &width)
 reset CRC on read or writen data
 
bool crc_status () const
 to known whether CRC calculation is activated or not
 
void get_crc (crc &val)
 get CRC of the transfered date since last reset
 
void sync_write ()
 write any pending data
 

Protected Member Functions

void set_mode (gf_mode x)
 
virtual U_I inherited_read (char *a, U_I size)=0
 implementation of read() operation
 
virtual void inherited_write (const char *a, U_I size)=0
 implementation of the write() operation
 
virtual void inherited_sync_write ()=0
 write down any pending data
 
virtual void inherited_terminate ()=0
 destructor-like call, except that it is allowed to throw exceptions
 
bool is_terminated () const
 

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 104 of file generic_file.hpp.

Member Function Documentation

bool libdar::generic_file::diff ( generic_file f,
crc &  value 
)

compares the contents with the object in argument

Parameters
[in]fis the file to compare the current object with
[in,out]valueis 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"
void libdar::generic_file::get_crc ( crc &  val)
inline

get CRC of the transfered date since last reset

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

Definition at line 201 of file generic_file.hpp.

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

implementation of read() operation

Parameters
[in,out]awhere to put the data to read
[in]sizesays 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::trivial_sar, libdar::sar, libdar::compressor, libdar::tuyau, libdar::tronc, libdar::zapette, libdar::cache, libdar::null_file, libdar::scrambler, and libdar::string_file.

virtual void libdar::generic_file::inherited_sync_write ( )
protectedpure virtual

write down any pending data

Note
this method is called after read/write mode checking from sync_write() public method;

Implemented in libdar::trivial_sar, libdar::sar, libdar::compressor, libdar::tuyau, libdar::tronc, libdar::zapette, libdar::cache, libdar::null_file, libdar::scrambler, and libdar::string_file.

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

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

implementation of the write() operation

Parameters
[in]awhat data to write
[in]sizeamount of data to write
Note
must either write all data or report an error by throwing an exception

Implemented in libdar::trivial_sar, libdar::sar, libdar::compressor, libdar::tuyau, libdar::tronc, libdar::zapette, libdar::cache, libdar::null_file, libdar::scrambler, and libdar::string_file.

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 245 of file generic_file.hpp.

Referenced by libdar::zapette::get_position(), libdar::tronconneuse::get_position(), libdar::trivial_sar::skip(), 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]ais where to put the data to read
[in]sizeis 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().

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

reset CRC on read or writen data

Parameters
[in]widthis 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]posthe 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::trivial_sar, libdar::sar, libdar::compressor, libdar::tronconneuse, libdar::tuyau, libdar::tronc, libdar::cache, libdar::zapette, libdar::null_file, libdar::scrambler, and libdar::string_file.

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

void libdar::generic_file::terminate ( ) const

virtual destructor, this let inherited destructor to be called even from a generic_file pointer to an inherited class

destructor-like call, except that it is allowed to throw exceptions

Referenced by libdar::tronc::inherited_terminate().

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

Referenced by libdar::trivial_sar::inherited_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: