Disk ARchive  2.4.10
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups
Public Member Functions | Protected Member Functions | List of all members
libdar::null_file Class Reference

the null_file class implements the /dev/null behavior More...

#include <null_file.hpp>

Inherits libdar::generic_file, and libdar::thread_cancellation.

Public Member Functions

 null_file (gf_mode m)
 
bool skip (const infinint &pos)
 skip at the absolute position More...
 
bool skip_to_eof ()
 skip to the end of file
 
bool skip_relative (signed int x)
 
infinint get_position ()
 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
 
void terminate () const
 virtual destructor, this let inherited destructor to be called even from a generic_file pointer to an inherited class More...
 
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 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 skip_relative (S_I x)=0
 skip relatively to the current 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 &crc_size, crc *&value)
 compares the contents with the object in argument More...
 
bool diff (generic_file &f, 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
 
- Public Member Functions inherited from libdar::thread_cancellation
 thread_cancellation ()
 the constructor
 
virtual ~thread_cancellation ()
 the destructor
 
void check_self_cancellation () const
 Checkpoint test : whether the current libdar call must abort or not. More...
 
void block_delayed_cancellation (bool mode)
 

Protected Member Functions

U_I inherited_read (char *a, U_I size)
 implementation of read() operation More...
 
void inherited_write (const char *a, U_I size)
 implementation of the write() operation More...
 
void inherited_sync_write ()
 write down any pending data More...
 
void inherited_terminate ()
 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
 

Additional Inherited Members

- Static Public Member Functions inherited from libdar::thread_cancellation
static void init ()
 mandatory initialization static method More...
 
static U_I count ()
 method for debugging/control purposes
 

Detailed Description

the null_file class implements the /dev/null behavior

this is a generic_file implementation that emulate the comportment of the /dev/null special file. all that is writen to is lost, and nothing can be read from it (empty file). This is a completed implementation all call are consistent.

Definition at line 50 of file null_file.hpp.

Member Function Documentation

U_I libdar::null_file::inherited_read ( char *  a,
U_I  size 
)
inlineprotectedvirtual

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.

Implements libdar::generic_file.

Definition at line 63 of file null_file.hpp.

References libdar::thread_cancellation::check_self_cancellation().

void libdar::null_file::inherited_sync_write ( )
inlineprotectedvirtual

write down any pending data

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

Implements libdar::generic_file.

Definition at line 78 of file null_file.hpp.

void libdar::null_file::inherited_terminate ( )
inlineprotectedvirtual

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.

Definition at line 80 of file null_file.hpp.

void libdar::null_file::inherited_write ( const char *  a,
U_I  size 
)
inlineprotectedvirtual

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

Implements libdar::generic_file.

Definition at line 71 of file null_file.hpp.

References libdar::thread_cancellation::check_self_cancellation().

bool libdar::null_file::skip ( const infinint pos)
inlinevirtual

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

Implements libdar::generic_file.

Definition at line 54 of file null_file.hpp.


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