Class (GI Struct)

GLib-2.0GLibIOChannel

The GLib.IOChannel data type aims to provide a portable method for using file descriptors, pipes, and sockets, and integrating them into the main event loop (see GLib.MainContext). Currently, full support is available on UNIX platforms; support for Windows is only partially complete.

To create a new GLib.IOChannel on UNIX systems use GLib.IOChannel.unix_new. This works for plain file descriptors, pipes and sockets. Alternatively, a channel can be created for a file in a system independent manner using GLib.IOChannel.new_file.

Once a GLib.IOChannel has been created, it can be used in a generic manner with the functions GLib.IOChannel.read_chars, GLib.IOChannel.write_chars, GLib.IOChannel.seek_position, and GLib.IOChannel.shutdown.

To add a GLib.IOChannel to the main event loop, use GLib.io_add_watch or GLib.io_add_watch_full. Here you specify which events you are interested in on the GLib.IOChannel, and provide a function to be called whenever these events occur.

GLib.IOChannel instances are created with an initial reference count of 1. GLib.IOChannel.ref and GLib.IOChannel.unref can be used to increment or decrement the reference count respectively. When the reference count falls to 0, the GLib.IOChannel is freed. (Though it isn’t closed automatically, unless it was created using GLib.IOChannel.new_file.) Using GLib.io_add_watch or GLib.io_add_watch_full increments a channel’s reference count.

The new functions GLib.IOChannel.read_chars, GLib.IOChannel.read_line, GLib.IOChannel.read_line_string, GLib.IOChannel.read_to_end, GLib.IOChannel.write_chars, GLib.IOChannel.seek_position, and GLib.IOChannel.flush should not be mixed with the deprecated functions GLib.IOChannel.read, GLib.IOChannel.write, and GLib.IOChannel.seek on the same channel.

Index

Constructors

Properties

Methods

  • Close an IO channel. Any pending data to be written will be flushed, ignoring errors. The channel will not be freed until the last reference is dropped using g_io_channel_unref().

    Returns void

  • Returns whether channel is buffered.

    Returns boolean

    true if the channel is buffered.

  • Returns whether the file/socket/whatever associated with channel will be closed when channel receives its final unref and is destroyed. The default value of this is true for channels created by g_io_channel_new_file (), and false for all other channels.

    Returns boolean

    true if the channel will be closed, false otherwise.

  • Gets the encoding for the input/output of the channel. The internal encoding is always UTF-8. The encoding null makes the channel safe for binary data.

    Returns string

    A string containing the encoding, this string is owned by GLib and must not be freed.

  • This returns the string that GLib.IOChannel uses to determine where in the file a line break occurs. A value of null indicates autodetection. Since 2.84, the return value is always nul-terminated.

    Returns [string, number]

    The line termination string. This value is owned by GLib and must not be freed.

  • Replacement for g_io_channel_read() with the new API.

    Returns [IOStatus, Uint8Array<ArrayBufferLike>, number]

    the status of the operation.

  • Replacement for g_io_channel_seek() with the new API.

    Parameters

    • offset: number

      The offset in bytes from the position specified by type

    • type: GLib.SeekType

      a GLib.SeekType. The type GLib.SeekType.CUR is only allowed in those cases where a call to g_io_channel_set_encoding () is allowed. See the documentation for g_io_channel_set_encoding () for details.

    Returns IOStatus

    the status of the operation.

  • Sets the buffer size.

    Parameters

    • size: number

      the size of the buffer, or 0 to let GLib pick a good size

    Returns void

  • The buffering state can only be set if the channel's encoding is null. 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.IOStatus.EOF not require such a flush. For write-only channels, a call to g_io_channel_flush () is sufficient. For all other channels, the buffers may be flushed by a call to g_io_channel_seek_position (). This includes the possibility of seeking with seek type GLib.SeekType.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.

    On unbuffered channels, it is safe to mix read and write calls from the new and old APIs, if this is necessary for maintaining old code.

    The default state of the channel is buffered.

    Parameters

    • buffered: boolean

      whether to set the channel buffered or unbuffered

    Returns void

  • Whether to close the channel on the final unref of the GLib.IOChannel data structure. The default value of this is true for channels created by g_io_channel_new_file (), and false for all other channels.

    Setting this flag to true for a channel you have already closed can cause problems when the final reference to the GLib.IOChannel is dropped.

    Parameters

    • do_close: boolean

      Whether to close the channel on the final unref of the GIOChannel data structure.

    Returns void

  • 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 null is safe to use with binary data.

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

    • The channel was just created, and has not been written to or read from yet.

    • The channel is write-only.

    • The channel is a file, and the file pointer was just repositioned by a call to g_io_channel_seek_position(). (This flushes all the internal buffers.)

    • The current encoding is null or UTF-8.

    • One of the (new API) read functions has just returned GLib.IOStatus.EOF (or, in the case of g_io_channel_read_to_end(), GLib.IOStatus.NORMAL).

    • One of the functions g_io_channel_read_chars() or g_io_channel_read_unichar() has returned GLib.IOStatus.AGAIN or GLib.IOStatus.ERROR. This may be useful in the case of GLib.ConvertError.ILLEGAL_SEQUENCE. Returning one of these statuses from g_io_channel_read_line(), g_io_channel_read_line_string(), or g_io_channel_read_to_end() does not guarantee that the encoding can be changed.

    Channels which do not meet one of the above conditions cannot call g_io_channel_seek_position() with an offset of GLib.SeekType.CUR, and, if they are "seekable", cannot call g_io_channel_write_chars() after calling one of the API "read" functions.

    Parameters

    • Optionalencoding: string

      the encoding type

    Returns IOStatus

    GLib.IOStatus.NORMAL if the encoding was successfully set

  • This sets the string that GLib.IOChannel uses to determine where in the file a line break occurs.

    Parameters

    • line_term: string

      The line termination string. Use null for autodetect. Autodetection breaks on "\n", "\r\n", "\r", "\0", and the Unicode paragraph separator. Autodetection should not be used for anything other than file-based channels.

    • length: number

      The length of the termination string. If -1 is passed, the string is assumed to be nul-terminated. This option allows termination strings with embedded nuls.

    Returns void

  • Close an IO 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 using g_io_channel_unref().

    Parameters

    • flush: boolean

      if true, flush pending

    Returns IOStatus

    the status of the operation.

  • Replacement for g_io_channel_write() with the new API.

    On seekable channels with encodings other than null or UTF-8, generic mixing of reading and writing is not allowed. A call to g_io_channel_write_chars () may only be made on a channel from which data has been read in the cases described in the documentation for g_io_channel_set_encoding ().

    Parameters

    • buf: string | Uint8Array<ArrayBufferLike>

      a buffer to write data from

    • count: number

      the size of the buffer. If -1, the buffer is taken to be a nul-terminated string.

    Returns [IOStatus, number]

    the status of the operation.