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Public Member Functions
FileHandle Class Referenceabstract

Class FileHandle. More...

#include <FileHandle.h>

Inheritance diagram for FileHandle:
NonCopyable< FileHandle > File FileLike SerialWireOutput UARTSerial TestFile< FILE_SIZE > Stream Serial

Public Member Functions

virtual ssize_t read (void *buffer, size_t size)=0
 Read the contents of a file into a buffer. More...
 
virtual ssize_t write (const void *buffer, size_t size)=0
 Write the contents of a buffer to a file. More...
 
virtual off_t seek (off_t offset, int whence=SEEK_SET)=0
 Move the file position to a given offset from from a given location. More...
 
virtual int close ()=0
 Close a file. More...
 
virtual int sync ()
 Flush any buffers associated with the file. More...
 
virtual int isatty ()
 Check if the file in an interactive terminal device. More...
 
virtual off_t tell ()
 Get the file position of the file. More...
 
virtual void rewind ()
 Rewind the file position to the beginning of the file. More...
 
virtual off_t size ()
 Get the size of the file. More...
 
virtual off_t lseek (off_t offset, int whence)
 Move the file position to a given offset from a given location. More...
 
virtual int fsync ()
 Flush any buffers associated with the FileHandle, ensuring it is up to date on disk. More...
 
virtual off_t flen ()
 Find the length of the file. More...
 
virtual int set_blocking (bool blocking)
 Set blocking or nonblocking mode of the file operation like read/write. More...
 
virtual bool is_blocking () const
 Check current blocking or nonblocking mode for file operations. More...
 
virtual short poll (short events) const
 Check for poll event flags You can use or ignore the input parameter. More...
 
bool writable () const
 Definition depends on the subclass implementing FileHandle. More...
 
bool readable () const
 Definition depends on the subclass implementing FileHandle. More...
 
virtual void sigio (Callback< void()> func)
 Register a callback on state change of the file. More...
 

Detailed Description

Class FileHandle.

An abstract interface that represents operations on a file-like object. The core functions are read, write and seek, but only a subset of these operations can be provided.

Note
to create a file,
See also
File
Note
Synchronization level: Set by subclass

Definition at line 46 of file FileHandle.h.

Member Function Documentation

virtual int close ( )
pure virtual

Close a file.

Returns
0 on success, negative error code on failure

Implemented in UARTSerial, TestFile< FILE_SIZE >, SerialWireOutput, File, and Stream.

virtual off_t flen ( )
virtual

Find the length of the file.

Returns
Length of the file
Deprecated:
Replaced by `off_t FileHandle::size()'

Definition at line 180 of file FileHandle.h.

virtual int fsync ( )
virtual

Flush any buffers associated with the FileHandle, ensuring it is up to date on disk.

Returns
0 on success or un-needed, -1 on error
Deprecated:
Replaced by `int FileHandle::sync()'

Definition at line 168 of file FileHandle.h.

virtual bool is_blocking ( ) const
virtual

Check current blocking or nonblocking mode for file operations.

Returns
true for blocking mode, false for nonblocking mode.

Reimplemented in UARTSerial.

Definition at line 203 of file FileHandle.h.

virtual int isatty ( )
virtual

Check if the file in an interactive terminal device.

Returns
True if the file is a terminal
False if the file is not a terminal
Negative error code on failure

Reimplemented in UARTSerial, File, Stream, and SerialWireOutput.

Definition at line 110 of file FileHandle.h.

virtual off_t lseek ( off_t  offset,
int  whence 
)
virtual

Move the file position to a given offset from a given location.

Parameters
offsetThe offset from whence to move to
whenceSEEK_SET for the start of the file, SEEK_CUR for the current file position, or SEEK_END for the end of the file.
Returns
new file position on success, -1 on failure or unsupported
Deprecated:
Replaced by `off_t FileHandle::seek(off_t offset, int whence = SEEK_SET)'

Definition at line 154 of file FileHandle.h.

virtual short poll ( short  events) const
virtual

Check for poll event flags You can use or ignore the input parameter.

You can return all events or check just the events listed in events. Call is nonblocking - returns instantaneous state of events. Whenever an event occurs, the derived class should call the sigio() callback).

Parameters
eventsbitmask of poll events we're interested in - POLLIN/POLLOUT etc.
Returns
bitmask of poll events that have occurred.

Reimplemented in UARTSerial.

Definition at line 218 of file FileHandle.h.

virtual ssize_t read ( void *  buffer,
size_t  size 
)
pure virtual

Read the contents of a file into a buffer.

Devices acting as FileHandles should follow POSIX semantics:

  • if no data is available, and nonblocking set, return -EAGAIN
  • if no data is available, and blocking set, wait until some data is available
  • If any data is available, call returns immediately
Parameters
bufferThe buffer to read in to
sizeThe number of bytes to read
Returns
The number of bytes read, 0 at end of file, negative error on failure

Implemented in UARTSerial, File, Stream, SerialWireOutput, and TestFile< FILE_SIZE >.

bool readable ( ) const

Definition depends on the subclass implementing FileHandle.

For example, if the FileHandle is of type Stream, readable() could return true when there is something available to read.

Returns
true when there is something available to read.

Definition at line 241 of file FileHandle.h.

virtual void rewind ( )
virtual

Rewind the file position to the beginning of the file.

Note
This is equivalent to seek(0, SEEK_SET)

Reimplemented in File, and Stream.

Definition at line 130 of file FileHandle.h.

virtual off_t seek ( off_t  offset,
int  whence = SEEK_SET 
)
pure virtual

Move the file position to a given offset from from a given location.

Parameters
offsetThe offset from whence to move to
whenceThe start of where to seek SEEK_SET to start from beginning of file, SEEK_CUR to start from current position in file, SEEK_END to start from end of file
Returns
The new offset of the file, negative error code on failure

Implemented in UARTSerial, File, TestFile< FILE_SIZE >, Stream, and SerialWireOutput.

virtual int set_blocking ( bool  blocking)
virtual

Set blocking or nonblocking mode of the file operation like read/write.

Definition depends on the subclass implementing FileHandle. The default is blocking.

Parameters
blockingtrue for blocking mode, false for nonblocking mode.
Returns
0 on success
Negative error code on failure

Reimplemented in UARTSerial.

Definition at line 194 of file FileHandle.h.

virtual void sigio ( Callback< void()>  func)
virtual

Register a callback on state change of the file.

The specified callback will be called on state changes such as when the file can be written to or read from.

The callback may be called in an interrupt context and should not perform expensive operations.

Note! This is not intended as an attach-like asynchronous API, but rather as a building block for constructing such functionality.

The exact timing of when the registered function is called is not guaranteed and is susceptible to change. It should be used as a cue to make read/write/poll calls to find the current state.

Parameters
funcFunction to call on state change

Reimplemented in UARTSerial.

Definition at line 263 of file FileHandle.h.

virtual off_t size ( )
virtual

Get the size of the file.

Returns
Size of the file in bytes

Reimplemented in File, Stream, and SerialWireOutput.

virtual int sync ( )
virtual

Flush any buffers associated with the file.

Returns
0 on success, negative error code on failure

Reimplemented in UARTSerial, File, and Stream.

Definition at line 99 of file FileHandle.h.

virtual off_t tell ( )
virtual

Get the file position of the file.

Note
This is equivalent to seek(0, SEEK_CUR)
Returns
The current offset in the file, negative error code on failure

Reimplemented in File, and Stream.

Definition at line 121 of file FileHandle.h.

bool writable ( ) const

Definition depends on the subclass implementing FileHandle.

For example, if the FileHandle is of type Stream, writable() could return true when there is ample buffer space available for write() calls.

Returns
true if the FileHandle is writable.

Definition at line 230 of file FileHandle.h.

virtual ssize_t write ( const void *  buffer,
size_t  size 
)
pure virtual

Write the contents of a buffer to a file.

Devices acting as FileHandles should follow POSIX semantics:

  • if blocking, block until all data is written
  • if no data can be written, and nonblocking set, return -EAGAIN
  • if some data can be written, and nonblocking set, write partial

    Parameters
    bufferThe buffer to write from
    sizeThe number of bytes to write
    Returns
    The number of bytes written, negative error on failure

Implemented in File, UARTSerial, Stream, TestFile< FILE_SIZE >, and SerialWireOutput.

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