FileDescriptor Class Reference

Abstraction of a file descriptor. More...

#include <FileDescriptor.hpp>

Inheritance diagram for FileDescriptor:

Public Member Functions
	FileDescriptor (const std::string &name, const int flags)
	Constructor for descriptors of files.
	FileDescriptor (const std::string &name, const int flags, const mode_t mode)
	Constructor for descriptors of files.
int	getLength ()
	Method to get the length of current available data.
int	lseek (int offset)
	Method to reposition at a certain offset.
void	sync ()
	Sync the descriptor.
Public Member Functions inherited from PosixDescriptor
virtual	~PosixDescriptor ()
	Destructor.
void	async_read (void(*handler)(Buffer *b, size_t size), Buffer *b, size_t size)
	Run asynchronous read operation.
void	async_read (void(*handler)(void *b, size_t size), void *b, size_t size)
	Run asynchronous read operation.
void	async_write (void(*handler)(Buffer *b, size_t size), Buffer *b, size_t size)
	Run asynchronous write operation.
void	async_write (void(*handler)(void *b, size_t size), void *b, size_t size)
	Run asynchronous write operation.
int	read (Buffer *b, size_t size)
	Method to read from the descriptor and fill a buffer.
int	read (void *p, size_t size)
	Method to read from the descriptor.
int	write (Buffer *b, size_t size)
	Method to write data in a buffer to the descriptor.
int	write (const void *p, size_t size)
	Method to write to the descriptor.
int	write (const std::string &s)
	Method to write a string to the descriptor.
virtual void	close ()
	Method to close the descriptor.
int	getDescriptorNumber () const
	Method to get descriptor number.
	PosixDescriptor (const PosixDescriptor &src)
	Copy constructor.
PosixDescriptor &	operator= (const PosixDescriptor &src)
	Assignment operator.
bool	flush ()
	Method to flush this specific descriptor.
int	ioctl (int request)
	Ioctl on the file descriptor.
int	ioctl (int request, void *argp)
	Ioctl on the file descriptor.

Additional Inherited Members
Protected Member Functions inherited from PosixDescriptor
int	do_read (void *p, size_t size)
	Low-level read.
int	do_write (const void *p, size_t size)
	Low-level write.
	PosixDescriptor ()
	Constructor.
Protected Attributes inherited from PosixDescriptor
int	fd_
	Number of the file descriptor.

Detailed Description

Abstraction of a file descriptor.

This is an abstract class for the concept of file descriptor. The descriptor corresponds to an open file.

Example of usage:

FileDescriptor fd ("/tmp/myfile", O_RDONLY);
Buffer b (10);
fd.read (b, b.getSize());

Definition at line 41 of file FileDescriptor.hpp.

Constructor & Destructor Documentation

FileDescriptor	(	const std::string &	name,
		const int	flags
	)

Constructor for descriptors of files.

It calls open() with the given flags.

Parameters

name	of the file
flags	that can be O_RDONLY O_WRONLY or O_RDWR or-ed with zero or more flags: O_APPEND O_ASYNC O_CREAT O_NONBLOCK O_SYNC

Exceptions

runtime_error

if the ::open() returns an error

Definition at line 48 of file FileDescriptor.cpp.

{
                fd_ = open(name.c_str(), flags);
                if (fd_ <= 0) {
                        ERROR("Opening file " << name);
                        throw std::runtime_error ("Open file error");
                }
}

FileDescriptor	(	const std::string &	name,
		const int	flags,
		const mode_t	mode
	)

Constructor for descriptors of files.

It calls open() with the given flags.

Parameters

name	of the file
flags	that can be O_RDONLY O_WRONLY or O_RDWR or-ed with zero or more flags: O_APPEND O_ASYNC O_CREAT O_NONBLOCK O_SYNC
mode	can be S_IRWXU 00700 user (file owner) has read, write and execute permission S_IRUSR 00400 user has read permission S_IWUSR 00200 user has write permission S_IXUSR 00100 user has execute permission S_IRWXG 00070 group has read, write and execute permission S_IRGRP 00040 group has read permission S_IWGRP 00020 group has write permission S_IXGRP 00010 group has execute permission S_IRWXO 00007 others have read, write and execute permission S_IROTH 00004 others have read permission S_IWOTH 00002 others have write permission S_IXOTH 00001 others have execute permission

Exceptions

runtime_error

if the ::open() returns an error

Definition at line 94 of file FileDescriptor.cpp.

{
                fd_ = open(name.c_str(), flags, mode);
                if (fd_ <= 0) {
                        ERROR("Opening file " << name);
                        throw std::runtime_error ("Open file error");
                }
}

Member Function Documentation

int getLength

(

)

Method to get the length of current available data.

Returns

length of data available on the file

Definition at line 111 of file FileDescriptor.cpp.

{
                int currentPosition = ::lseek(fd_, 0, SEEK_CUR);
                int end = ::lseek(fd_, 0, SEEK_END);
                ::lseek(fd_, currentPosition, SEEK_SET);
                return end;
}

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int lseek ( int  offset )

inline

Method to reposition at a certain offset.

Parameters

offset

Offset from the beginning of file

Returns

the actual offset location in case of success; -1 in case of error

Definition at line 56 of file FileDescriptor.hpp.

                                     {
                return ::lseek(fd_, offset, SEEK_SET);
        }

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void sync ( )

inline

Sync the descriptor.

Method to call fsync on the descriptor. Usually after a write operation.

Definition at line 67 of file FileDescriptor.hpp.

                          {
                ::fsync(fd_);
        }

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

• /home/cloud/work/onposix-code/include/FileDescriptor.hpp
• /home/cloud/work/onposix-code/src/FileDescriptor.cpp