casacore::FiledesIO Class Reference

Class for unbuffered IO on a file. More...

#include <FiledesIO.h>

Inheritance diagram for casacore::FiledesIO:

Public Member Functions
	FiledesIO ()
	Default constructor. More...
	FiledesIO (int fd, const String &fileName=String())
	Construct from the given file descriptor. More...
void	attach (int fd, const String &fileName)
	Attach to the given file descriptor. More...
void	detach ()
	Detach from the file descriptor. More...
virtual	~FiledesIO ()
	The destructor detaches, but does not close the file. More...
virtual void	write (Int64 size, const void *buf)
	Write the number of bytes. More...
virtual void	pwrite (Int64 size, Int64 offset, const void *buf)
	Write the number of bytes at offset from start of the file. More...
virtual Int64	read (Int64 size, void *buf, Bool throwException=True)
	Read size bytes from the descriptor. More...
virtual Int64	pread (Int64 size, Int64 offset, void *buf, Bool throwException=True)
	Like read except reads from offset of the start of the file. More...
virtual Int64	length ()
	Get the length of the byte stream. More...
virtual Bool	isReadable () const
	Is the IO stream readable? More...
virtual Bool	isWritable () const
	Is the IO stream writable? More...
virtual Bool	isSeekable () const
	Is the IO stream seekable? More...
void	setWritable ()
	Set that the IO stream is writable. More...
virtual String	fileName () const
	Get the file name of the file attached. More...
virtual void	fsync ()
	Fsync the file (i.e. More...
Public Member Functions inherited from casacore::ByteIO
	ByteIO ()
	The constructor does nothing. More...
virtual	~ByteIO ()
virtual void	reopenRW ()
	Reopen the underlying IO stream for read/write access. More...
Int64	seek (Int offset, ByteIO::SeekOption=ByteIO::Begin)
	This function sets the position on the given offset. More...
Int64	seek (Int64 offset, ByteIO::SeekOption=ByteIO::Begin)
virtual void	flush ()
	Flush the data to the file. More...
virtual void	resync ()
	Resync the file (i.e. More...

Static Public Member Functions
static int	create (const Char *name, int mode=0666)
	Some static convenience functions for file create/open/close. More...
static int	open (const Char *name, Bool writable=False, Bool throwExcp=True)
static void	close (int fd)

Protected Member Functions
int	fd () const
	Get the file descriptor. More...
void	fillRWFlags (int fd)
	Determine if the file descriptor is readable and/or writable. More...
void	fillSeekable ()
	Determine if the file is seekable. More...
virtual Int64	doSeek (Int64 offset, ByteIO::SeekOption)
	Reset the position pointer to the given value. More...
Protected Member Functions inherited from casacore::ByteIO
	ByteIO (const ByteIO &byteIO)
	Make copy constructor and assignment protected, so a user cannot use them (but a derived class can). More...
ByteIO &	operator= (const ByteIO &byteIO)

Private Member Functions
	FiledesIO (const FiledesIO &that)
	Copy constructor, should not be used. More...
FiledesIO &	operator= (const FiledesIO &that)
	Assignment, should not be used. More...

Private Attributes
Bool	itsSeekable
Bool	itsReadable
Bool	itsWritable
int	itsFile
String	itsFileName

Additional Inherited Members
Public Types inherited from casacore::ByteIO
enum	OpenOption {   Old,   Update,   Append,   New,   NewNoReplace,   Scratch,   Delete }
	Define the possible ByteIO open options. More...
enum	SeekOption {   Begin,   Current,   End }
	Define the possible seek options. More...

Detailed Description

Class for unbuffered IO on a file.

Intended use:

Public interface

Review Status

Reviewed By:

Friso Olnon

Date Reviewed:

1996/11/06

Test programs:

tByteIO

Prerequisite

• ByteIO class
• file descriptors

Synopsis

This class is a specialization of class ByteIO. It uses a file descriptor to read/write data.

The file associated with the file descriptor has to be opened before hand. The constructor will determine automatically if the file is readable, writable and seekable. Note that on destruction the file descriptor is NOT closed.

Example

This example shows how FiledesIO can be used with an fd. It uses the fd for a regular file, which could be done in an easier way using class RegularFileIO. However, when using pipes or sockets, this would be the only way.

// Get a file descriptor for the file.
int fd = open ("file.name");
// Use that as the source of AipsIO (which will also use CanonicalIO).
FiledesIO fio (fd);
AipsIO stream (&fio);
// Read the data.
Int vali;
Bool valb;
stream >> vali >> valb;

Motivation

Make it possible to use the Casacore IO functionality on any file. In this way any device can be hooked to the IO framework.

Definition at line 88 of file FiledesIO.h.

Constructor & Destructor Documentation

casacore::FiledesIO::FiledesIO

(

)

Default constructor.

A stream can be attached using the attach function.

casacore::FiledesIO::FiledesIO ( int  fd, const String &  fileName = String()  )

explicit

Construct from the given file descriptor.

The file name is only used in possible error messages.

virtual casacore::FiledesIO::~FiledesIO ( )

virtual

The destructor detaches, but does not close the file.

casacore::FiledesIO::FiledesIO ( const FiledesIO &  that )

private

Copy constructor, should not be used.

Member Function Documentation

void casacore::FiledesIO::attach	(	int	fd,
		const String &	fileName
	)

Attach to the given file descriptor.

An exception is thrown if it is not in a detached state. The file name is only used in error messages.

static void casacore::FiledesIO::close ( int  fd )

static

static int casacore::FiledesIO::create ( const Char *  name, int  mode = 0666  )

static

Some static convenience functions for file create/open/close.

Close is only done if the fd is non-negative.

void casacore::FiledesIO::detach

(

)

Detach from the file descriptor.

The file is not closed.

virtual Int64 casacore::FiledesIO::doSeek ( Int64  offset, ByteIO::SeekOption    )

protectedvirtual

Reset the position pointer to the given value.

It returns the new position.

Implements casacore::ByteIO.

Reimplemented in casacore::MMapfdIO.

int casacore::FiledesIO::fd ( ) const

inlineprotected

Get the file descriptor.

Definition at line 163 of file FiledesIO.h.

References itsFile.

virtual String casacore::FiledesIO::fileName ( ) const

virtual

Get the file name of the file attached.

Reimplemented from casacore::ByteIO.

void casacore::FiledesIO::fillRWFlags ( int  fd )

protected

Determine if the file descriptor is readable and/or writable.

void casacore::FiledesIO::fillSeekable ( )

protected

Determine if the file is seekable.

virtual void casacore::FiledesIO::fsync ( )

virtual

Fsync the file (i.e.

force the data to be physically written).

Reimplemented from casacore::ByteIO.

virtual Bool casacore::FiledesIO::isReadable ( ) const

virtual

Is the IO stream readable?

Implements casacore::ByteIO.

virtual Bool casacore::FiledesIO::isSeekable ( ) const

virtual

Is the IO stream seekable?

Implements casacore::ByteIO.

virtual Bool casacore::FiledesIO::isWritable ( ) const

virtual

Is the IO stream writable?

Implements casacore::ByteIO.

virtual Int64 casacore::FiledesIO::length ( )

virtual

Get the length of the byte stream.

Implements casacore::ByteIO.

static int casacore::FiledesIO::open ( const Char *  name, Bool  writable = False, Bool  throwExcp = True  )

static

FiledesIO& casacore::FiledesIO::operator= ( const FiledesIO &  that )

private

Assignment, should not be used.

virtual Int64 casacore::FiledesIO::pread ( Int64  size, Int64  offset, void *  buf, Bool  throwException = True  )

virtual

Like read except reads from offset of the start of the file.

The file offset is not changed

Reimplemented from casacore::ByteIO.

virtual void casacore::FiledesIO::pwrite ( Int64  size, Int64  offset, const void *  buf  )

virtual

Write the number of bytes at offset from start of the file.

The file offset is not changed

Reimplemented from casacore::ByteIO.

virtual Int64 casacore::FiledesIO::read ( Int64  size, void *  buf, Bool  throwException = True  )

virtual

Read size bytes from the descriptor.

Returns the number of bytes actually read or a negative number if an error occurred. Will throw an Exception (AipsError) if the requested number of bytes could not be read, or an error occured, unless throwException is set to False. Will always throw an exception if the descriptor is not readable or the system call returned an undocumented value.

Implements casacore::ByteIO.

Reimplemented in casacore::MMapfdIO.

void casacore::FiledesIO::setWritable ( )

inline

Set that the IO stream is writable.

Definition at line 142 of file FiledesIO.h.

References itsWritable, and casacore::True.

virtual void casacore::FiledesIO::write ( Int64  size, const void *  buf  )

virtual

Write the number of bytes.

Implements casacore::ByteIO.

Reimplemented in casacore::MMapfdIO.

Member Data Documentation

int casacore::FiledesIO::itsFile

private

Definition at line 180 of file FiledesIO.h.

Referenced by fd().

String casacore::FiledesIO::itsFileName

private

Definition at line 181 of file FiledesIO.h.

Bool casacore::FiledesIO::itsReadable

private

Definition at line 178 of file FiledesIO.h.

Bool casacore::FiledesIO::itsSeekable

private

Definition at line 177 of file FiledesIO.h.

Bool casacore::FiledesIO::itsWritable

private

Definition at line 179 of file FiledesIO.h.

Referenced by setWritable().

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

• casa/casacore/casa/IO/FiledesIO.h