glibmm: Glib::IOChannel Class Reference

IOChannel aims to provide portable I/O support for files, pipes and sockets, and to integrate them with the GLib main event loop. More...

#include <glibmm/iochannel.h>

Inheritance diagram for Glib::IOChannel:

Public Member Functions

virtual ~IOChannel ()
 
IOStatus read (gunichar& thechar)
 Read a single UCS-4 character. More...

 
IOStatus read (char* buf, gsize count, gsize& bytes_read)
 Read a character sequence into memory. More...

 
IOStatus read (Glib::ustring& str, gsize count)
 Read a maximum of count bytes into str. More...

 
IOStatus read_line (Glib::ustring& line)
 Read a whole line. More...

 
IOStatus read_to_end (Glib::ustring& str)
 Reads all the remaining data from the file. More...

 
IOStatus write (const Glib::ustring& str)
 Write a string to the I/O channel. More...

 
IOStatus write (const char* buf, gssize count, gsize& bytes_written)
 Write a memory area of count bytes to the I/O channel. More...

 
IOStatus write (gunichar unichar)
 Write a single UCS-4 character to the I/O channel. More...

 
IOStatus seek (gint64 offset, SeekType type=SEEK_TYPE_SET)
 Seek the I/O channel to a specific position. More...

 
IOStatus flush ()
 Flush the buffers of the I/O channel. More...

 
IOStatus close (bool flush_pending=true)
 Close the I/O channel. More...

 
gsize get_buffer_size () const
 Get the IOChannel internal buffer size. More...

 
void set_buffer_size (gsize size)
 Set the internal IOChannel buffer size. More...

 
IOFlags get_flags () const
 Get the current flags for a IOChannel, including read-only flags such as Glib::IO_FLAG_IS_READABLE. More...

 
IOStatus set_flags (IOFlags flags)
 Set flags on the IOChannel. More...

 
void set_buffered (bool buffered)
 Set the buffering status of the I/O channel. More...

 
bool get_buffered () const
 Get the buffering status of the I/O channel. More...

 
IOCondition get_buffer_condition () const
 Returns an IOCondition depending on whether there is data to be read/space to write data in the internal buffers in the I/O channel. More...

 
bool get_close_on_unref () const
 Returns whether the file/socket/whatever associated with the I/O channel will be closed when the channel receives its final unref and is destroyed. More...

 
void set_close_on_unref (bool do_close)
 Setting this flag to true for a channel you have already closed can cause problems. More...

 
IOStatus set_encoding (const std::string& encoding=std::string())
 Sets the encoding for the input/output of the channel. More...

 
std::string get_encoding () const
 Get the encoding of the I/O channel. More...

 
void set_line_term (const std::string& term=std::string())
 
std::string get_line_term () const
 
Glib::RefPtr< IOSourcecreate_watch (IOCondition condition)
 Creates an IOSource object. More...

 
virtual void reference () const
 
virtual void unreference () const
 
GIOChannel* gobj ()
 
const GIOChannel* gobj () const
 
- Public Member Functions inherited from sigc::trackable
 trackable () noexcept
 
 trackable (const trackable &src) noexcept
 
 trackable (trackable &&src)
 
 ~trackable ()
 
void add_destroy_notify_callback (void *data, func_destroy_notify func) const
 
void notify_callbacks ()
 
trackableoperator= (const trackable &src)
 
trackableoperator= (trackable &&src)
 
void remove_destroy_notify_callback (void *data) const
 

Static Public Member Functions

static Glib::RefPtr< IOChannelcreate_from_file (const std::string& filename, const std::string& mode)
 Open a file filename as an I/O channel using mode mode. More...

 
static Glib::RefPtr< IOChannelcreate_from_fd (int fd)
 Creates an I/O channel from a file descriptor. More...

 
static Glib::RefPtr< IOChannelcreate_from_win32_fd (int fd)
 Create an I/O channel for C runtime (emulated Unix-like) file descriptors. More...

 
static Glib::RefPtr< IOChannelcreate_from_win32_socket (int socket)
 Create an I/O channel for a winsock socket. More...

 

Protected Member Functions

 IOChannel ()
 Constructor that should be used by derived classes. More...

 
virtual IOStatus read_vfunc (char* buf, gsize count, gsize& bytes_read)
 
virtual IOStatus write_vfunc (const char* buf, gsize count, gsize& bytes_written)
 
virtual IOStatus seek_vfunc (gint64 offset, SeekType type)
 
virtual IOStatus close_vfunc ()
 
virtual IOStatus set_flags_vfunc (IOFlags flags)
 
virtual IOFlags get_flags_vfunc ()
 
virtual Glib::RefPtr< Glib::Sourcecreate_watch_vfunc (IOCondition cond)
 

Protected Attributes

GIOChannel* gobject_
 

Additional Inherited Members

- Public Types inherited from sigc::trackable
typedef internal::func_destroy_notify func_destroy_notify
 

Detailed Description

IOChannel aims to provide portable I/O support for files, pipes and sockets, and to integrate them with the GLib main event loop.

Note that IOChannels implement an automatic implicit character set conversion to the data stream, and usually will not pass by default binary data unchanged. To set the encoding of the channel, use e.g. set_encoding("ISO-8859-15"). To set the channel to no encoding, use set_encoding() without any arguments.

You can create an IOChannel with one of the static create methods.

Constructor & Destructor Documentation

virtual Glib::IOChannel::~IOChannel ( )
virtual
Glib::IOChannel::IOChannel ( )
protected

Constructor that should be used by derived classes.

Use this constructor if you want to inherit from IOChannel. It will set up a GIOChannel that will call the vfuncs of your class even if it is being used from C code, and it will keep a reference to the C++ code while the GIOChannel exists.

Member Function Documentation

IOStatus Glib::IOChannel::close ( bool  flush_pending = true)

Close the I/O channel.

Any pending data to be written will be flushed if flush is true. The channel will not be freed until the last reference is dropped. Accessing the channel after closing it is considered an error.

Parameters
flush_pendingWhether to flush() pending data before closing the channel.
Returns
The status of the operation.
Exceptions
Glib::IOChannelError
virtual IOStatus Glib::IOChannel::close_vfunc ( )
protectedvirtual
Deprecated:
Custom Glib::IOChannel implementation was never really supported.

Reimplemented in Glib::StreamIOChannel.

static Glib::RefPtr<IOChannel> Glib::IOChannel::create_from_fd ( int  fd)
static

Creates an I/O channel from a file descriptor.

On Unix, IOChannels created with this function work for any file descriptor or socket.

On Win32, this can be used either for files opened with the MSVCRT (the Microsoft run-time C library) _open() or _pipe(), including file descriptors 0, 1 and 2 (corresponding to stdin, stdout and stderr), or for Winsock SOCKETs. If the parameter is a legal file descriptor, it is assumed to be such, otherwise it should be a SOCKET. This relies on SOCKETs and file descriptors not overlapping. If you want to be certain, call either create_from_win32_fd() or create_from_win32_socket() instead as appropriate.

The term file descriptor as used in the context of Win32 refers to the emulated Unix-like file descriptors MSVCRT provides. The native corresponding concept is file HANDLE. There isn't as of yet a way to get IOChannels for Win32 file HANDLEs.

static Glib::RefPtr<IOChannel> Glib::IOChannel::create_from_file ( const std::string filename,
const std::string mode 
)
static

Open a file filename as an I/O channel using mode mode.

This channel will be closed when the last reference to it is dropped, so there is no need to call close() (though doing so will not cause problems, as long as no attempt is made to access the channel after it is closed).

Parameters
filenameThe name of the file to open.
modeOne of "r", "w", "a", "r+", "w+", "a+". These have the same meaning as in fopen().
Returns
An IOChannel for the opened file.
Exceptions
Glib::FileError
static Glib::RefPtr<IOChannel> Glib::IOChannel::create_from_win32_fd ( int  fd)
static

Create an I/O channel for C runtime (emulated Unix-like) file descriptors.

After calling add_watch() on a I/O channel returned by this function, you shouldn't call read() on the file descriptor. This is because adding polling for a file descriptor is implemented on Win32 by starting a thread that sits blocked in a read() from the file descriptor most of the time. All reads from the file descriptor should be done by this internal GLib thread. Your code should call only IOChannel::read().

static Glib::RefPtr<IOChannel> Glib::IOChannel::create_from_win32_socket ( int  socket)
static

Create an I/O channel for a winsock socket.

The parameter should be a SOCKET. Contrary to I/O channels for file descriptors (on Win32), you can use normal recv() or recvfrom() on sockets even if GLib is polling them.

Glib::RefPtr<IOSource> Glib::IOChannel::create_watch ( IOCondition  condition)

Creates an IOSource object.

Create a slot from a function to be called when condition is met for the channel with sigc::ptr_fun() or sigc::mem_fun() and pass it into the connect() function of the returned IOSource object. Polling of the channel will start when you attach a MainContext object to the returned IOSource object using its attach() function.

Glib::signal_io().connect() is a simpler interface to the same functionality, for the case where you want to add the source to the default main context.

Parameters
conditionThe condition to watch for.
Returns
An IOSource object that can be polled from a MainContext's event loop.
virtual Glib::RefPtr<Glib::Source> Glib::IOChannel::create_watch_vfunc ( IOCondition  cond)
protectedvirtual
Deprecated:
Custom Glib::IOChannel implementation was never really supported.

Reimplemented in Glib::StreamIOChannel.

IOStatus Glib::IOChannel::flush ( )

Flush the buffers of the I/O channel.

Returns
The status of the operation.
Exceptions
Glib::IOChannelError
Glib::ConvertError
IOCondition Glib::IOChannel::get_buffer_condition ( ) const

Returns an IOCondition depending on whether there is data to be read/space to write data in the internal buffers in the I/O channel.

Only the flags Glib::IO_IN and Glib::IO_OUT may be set.

Returns
Bitwise combination of Glib::IOCondition flags.
gsize Glib::IOChannel::get_buffer_size ( ) const

Get the IOChannel internal buffer size.

Returns
The buffer size.
bool Glib::IOChannel::get_buffered ( ) const

Get the buffering status of the I/O channel.

Returns
The buffering status of the channel.
bool Glib::IOChannel::get_close_on_unref ( ) const

Returns whether the file/socket/whatever associated with the I/O channel will be closed when the channel receives its final unref and is destroyed.

The default value of this is true for channels created by create_from_file(), and false for all other channels.

Returns
Whether the channel will be closed on the final unref of the IOChannel object.
std::string Glib::IOChannel::get_encoding ( ) const

Get the encoding of the I/O channel.

Returns
The current encoding of the channel.
IOFlags Glib::IOChannel::get_flags ( ) const

Get the current flags for a IOChannel, including read-only flags such as Glib::IO_FLAG_IS_READABLE.

The values of the flags Glib::IO_FLAG_IS_READABLE and Glib::IO_FLAG_IS_WRITEABLE are cached for internal use by the channel when it is created. If they should change at some later point (e.g. partial shutdown of a socket with the UNIX shutdown() function), the user should immediately call get_flags() to update the internal values of these flags.

Returns
Bitwise combination of the flags set on the channel.
virtual IOFlags Glib::IOChannel::get_flags_vfunc ( )
protectedvirtual
Deprecated:
Custom Glib::IOChannel implementation was never really supported.

Reimplemented in Glib::StreamIOChannel.

std::string Glib::IOChannel::get_line_term ( ) const
GIOChannel* Glib::IOChannel::gobj ( )
inline
const GIOChannel* Glib::IOChannel::gobj ( ) const
inline
IOStatus Glib::IOChannel::read ( gunichar &  thechar)

Read a single UCS-4 character.

Parameters
[out]thecharThe Unicode character.
Returns
The status of the operation.
Exceptions
Glib::IOChannelError
Glib::ConvertError
IOStatus Glib::IOChannel::read ( char *  buf,
gsize  count,
gsize &  bytes_read 
)

Read a character sequence into memory.

Parameters
bufA buffer to read data into.
countThe size of the buffer in bytes. Note that the buffer may not be complelely filled even if there is data in the buffer if the remaining data is not a complete character.
[out]bytes_readThe number of bytes read. This may be zero even on success if count < 6 and the channel's encoding is not "". This indicates that the next UTF-8 character is too wide for the buffer.
Returns
The status of the operation.
Exceptions
Glib::IOChannelError
Glib::ConvertError
IOStatus Glib::IOChannel::read ( Glib::ustring str,
gsize  count 
)

Read a maximum of count bytes into str.

Parameters
[out]strThe characters that have been read.
countThe maximum number of bytes to read.
Returns
The status of the operation.
Exceptions
Glib::IOChannelError
Glib::ConvertError
IOStatus Glib::IOChannel::read_line ( Glib::ustring line)

Read a whole line.

Reads until the line separator is found, which is included in the result string.

Parameters
[out]lineThe line that was read.
Returns
The status of the operation.
Exceptions
Glib::IOChannelError
Glib::ConvertError
IOStatus Glib::IOChannel::read_to_end ( Glib::ustring str)

Reads all the remaining data from the file.

Parameters
[out]strThe resulting string.
Returns
Glib::IO_STATUS_NORMAL on success. This function never returns Glib::IO_STATUS_EOF.
Exceptions
Glib::IOChannelError
Glib::ConvertError
virtual IOStatus Glib::IOChannel::read_vfunc ( char *  buf,
gsize  count,
gsize &  bytes_read 
)
protectedvirtual
Deprecated:
Custom Glib::IOChannel implementation was never really supported.

Reimplemented in Glib::StreamIOChannel.

virtual void Glib::IOChannel::reference ( ) const
virtual
IOStatus Glib::IOChannel::seek ( gint64  offset,
SeekType  type = SEEK_TYPE_SET 
)

Seek the I/O channel to a specific position.

Parameters
offsetThe offset in bytes from the position specified by type.
typeA SeekType. The type Glib::SEEK_TYPE_CUR is only allowed in those cases where a call to set_encoding() is allowed. See the documentation for set_encoding() for details.
Returns
The status of the operation.
Exceptions
Glib::IOChannelError
Glib::ConvertError
virtual IOStatus Glib::IOChannel::seek_vfunc ( gint64  offset,
SeekType  type 
)
protectedvirtual
Deprecated:
Custom Glib::IOChannel implementation was never really supported.

Reimplemented in Glib::StreamIOChannel.

void Glib::IOChannel::set_buffer_size ( gsize  size)

Set the internal IOChannel buffer size.

Parameters
sizeThe buffer size the IOChannel should use.
void Glib::IOChannel::set_buffered ( bool  buffered)

Set the buffering status of the I/O channel.

The buffering state can only be set if the channel's encoding is "". For any other encoding, the channel must be buffered.

A buffered channel can only be set unbuffered if the channel's internal buffers have been flushed. Newly created channels or channels which have returned Glib::IO_STATUS_EOF not require such a flush. For write-only channels, a call to flush() is sufficient. For all other channels, the buffers may be flushed by a call to seek(). This includes the possibility of seeking with seek type Glib::SEEK_TYPE_CUR and an offset of zero. Note that this means that socket-based channels cannot be set unbuffered once they have had data read from them.

The default state of the channel is buffered.

Parameters
bufferedWhether to set the channel buffered or unbuffered.
void Glib::IOChannel::set_close_on_unref ( bool  do_close)

Setting this flag to true for a channel you have already closed can cause problems.

Parameters
do_closeWhether to close the channel on the final unref of the IOChannel object. The default value of this is true for channels created by create_from_file(), and false for all other channels.
IOStatus Glib::IOChannel::set_encoding ( const std::string encoding = std::string())

Sets the encoding for the input/output of the channel.

The internal encoding is always UTF-8. The default encoding for the external file is UTF-8. The encoding "" is safe to use with binary data.

The encoding can only be set if one of the following conditions is true:

  1. The channel was just created, and has not been written to or read from yet.
  2. The channel is write-only.
  3. The channel is a file, and the file pointer was just repositioned by a call to seek_position(). (This flushes all the internal buffers.)
  4. The current encoding is "" or UTF-8.
  5. One of the read methods has just returned Glib::IO_STATUS_EOF (or, in the case of read_to_end(), Glib::IO_STATUS_NORMAL).
  6. The read() method has returned Glib::IO_STATUS_AGAIN or thrown a Glib::Error exception. This may be useful in the case of ConvertError::ILLEGAL_SEQUENCE. Returning one of these statuses from read_line() or read_to_end() does not guarantee that the encoding can be changed.

Channels which do not meet one of the above conditions cannot call seek_position() with a seek type of Glib::SEEK_TYPE_CUR and, if they are "seekable", cannot call write() after calling one of the API "read" methods.

Parameters
encodingThe encoding name, or "" for binary.
Returns
Glib::IO_STATUS_NORMAL if the encoding was successfully set.
Exceptions
Glib::IOChannelError
IOStatus Glib::IOChannel::set_flags ( IOFlags  flags)

Set flags on the IOChannel.

Parameters
flagsBitwise combination of the flags to set.
Returns
The operation result code.
Exceptions
Glib::IOChannelError
virtual IOStatus Glib::IOChannel::set_flags_vfunc ( IOFlags  flags)
protectedvirtual
Deprecated:
Custom Glib::IOChannel implementation was never really supported.

Reimplemented in Glib::StreamIOChannel.

void Glib::IOChannel::set_line_term ( const std::string term = std::string())
virtual void Glib::IOChannel::unreference ( ) const
virtual
IOStatus Glib::IOChannel::write ( const Glib::ustring str)

Write a string to the I/O channel.

Note that this method does not return the number of characters written. If the channel is blocking and the returned value is Glib::IO_STATUS_NORMAL, the whole string was written.

Parameters
strthe string to write.
Returns
The status of the operation.
Exceptions
Glib::IOChannelError
Glib::ConvertError
IOStatus Glib::IOChannel::write ( const char *  buf,
gssize  count,
gsize &  bytes_written 
)

Write a memory area of count bytes to the I/O channel.

Parameters
bufThe start of the memory area.
countThe number of bytes to write.
[out]bytes_writtenThe number of bytes written to the channel.
Returns
The status of the operation.
Exceptions
Glib::IOChannelError
Glib::ConvertError
IOStatus Glib::IOChannel::write ( gunichar  unichar)

Write a single UCS-4 character to the I/O channel.

Parameters
unicharThe character to write.
Returns
The status of the operation.
Exceptions
Glib::IOChannelError
Glib::ConvertError
virtual IOStatus Glib::IOChannel::write_vfunc ( const char *  buf,
gsize  count,
gsize &  bytes_written 
)
protectedvirtual
Deprecated:
Custom Glib::IOChannel implementation was never really supported.

Reimplemented in Glib::StreamIOChannel.

Member Data Documentation

GIOChannel* Glib::IOChannel::gobject_
protected