:right-sidebar: True

Seekable
===================================================================

.. currentmodule:: gi.repository.Gio





.. class:: Seekable(*args, **kwargs)
   :no-contents-entry:





Implementations: :class:`~gi.repository.Gio.BufferedInputStream`, :class:`~gi.repository.Gio.BufferedOutputStream`, :class:`~gi.repository.Gio.DataInputStream`, :class:`~gi.repository.Gio.DataOutputStream`, :class:`~gi.repository.Gio.FileIOStream`, :class:`~gi.repository.Gio.FileInputStream`, :class:`~gi.repository.Gio.FileOutputStream`, :class:`~gi.repository.Gio.MemoryInputStream`, :class:`~gi.repository.Gio.MemoryOutputStream`


``GSeekable`` is implemented by streams (implementations of
:obj:`~gi.repository.Gio.InputStream` or :obj:`~gi.repository.Gio.OutputStream`\) that support seeking.

Seekable streams largely fall into two categories: resizable and
fixed-size.

``GSeekable`` on fixed-sized streams is approximately the same as POSIX
```lseek()`` <man:lseek(2)>`__ on a block device (for example: attempting to seek
past the end of the device is an error).  Fixed streams typically cannot be
truncated.

``GSeekable`` on resizable streams is approximately the same as POSIX
```lseek()`` <man:lseek(2)>`__ on a normal file.  Seeking past the end and writing
data will usually cause the stream to resize by introducing zero bytes.




Methods
-------

.. rst-class:: interim-class

.. class:: Seekable
   :no-index:


   .. method:: can_seek() -> bool

      Tests if the stream supports the ``GSeekableIface``.









   .. method:: can_truncate() -> bool

      Tests if the length of the stream can be adjusted with
      :func:`~gi.repository.Gio.Seekable.truncate`.









   .. method:: seek(offset: int, type: ~gi.repository.GLib.SeekType, cancellable: ~gi.repository.Gio.Cancellable | None = None) -> bool

      Seeks in the stream by the given ``offset``\, modified by ``type``\.

      Attempting to seek past the end of the stream will have different
      results depending on if the stream is fixed-sized or resizable.  If
      the stream is resizable then seeking past the end and then writing
      will result in zeros filling the empty space.  Seeking past the end
      of a resizable stream and reading will result in EOF.  Seeking past
      the end of a fixed-sized stream will fail.

      Any operation that would result in a negative offset will fail.

      If ``cancellable`` is not :const:`None`, then the operation can be cancelled by
      triggering the cancellable object from another thread. If the operation
      was cancelled, the error :const:`~gi.repository.Gio.IOErrorEnum.CANCELLED` will be returned.






      :param offset: a :obj:`~gi.repository.gint64`\.

      :param type: a :obj:`~gi.repository.GLib.SeekType`\.

      :param cancellable: optional :obj:`~gi.repository.Gio.Cancellable` object, :const:`None` to ignore.




   .. method:: tell() -> int

      Tells the current position within the stream.









   .. method:: truncate(offset: int, cancellable: ~gi.repository.Gio.Cancellable | None = None) -> bool

      Sets the length of the stream to ``offset``\. If the stream was previously
      larger than ``offset``\, the extra data is discarded. If the stream was
      previously shorter than ``offset``\, it is extended with NUL ('\0') bytes.

      If ``cancellable`` is not :const:`None`, then the operation can be cancelled by
      triggering the cancellable object from another thread. If the operation
      was cancelled, the error :const:`~gi.repository.Gio.IOErrorEnum.CANCELLED` will be returned. If an
      operation was partially finished when the operation was cancelled the
      partial result will be returned, without an error.






      :param offset: new length for ``seekable``\, in bytes.

      :param cancellable: optional :obj:`~gi.repository.Gio.Cancellable` object, :const:`None` to ignore.












Virtual Methods
---------------

.. rst-class:: interim-class

.. class:: Seekable
   :no-index:
   

   .. method:: do_can_seek() -> bool

      Tests if the stream supports the ``GSeekableIface``.









   .. method:: do_can_truncate() -> bool

      Tests if the length of the stream can be adjusted with
      :func:`~gi.repository.Gio.Seekable.truncate`.









   .. method:: do_seek(offset: int, type: ~gi.repository.GLib.SeekType, cancellable: ~gi.repository.Gio.Cancellable | None = None) -> bool

      Seeks in the stream by the given ``offset``\, modified by ``type``\.

      Attempting to seek past the end of the stream will have different
      results depending on if the stream is fixed-sized or resizable.  If
      the stream is resizable then seeking past the end and then writing
      will result in zeros filling the empty space.  Seeking past the end
      of a resizable stream and reading will result in EOF.  Seeking past
      the end of a fixed-sized stream will fail.

      Any operation that would result in a negative offset will fail.

      If ``cancellable`` is not :const:`None`, then the operation can be cancelled by
      triggering the cancellable object from another thread. If the operation
      was cancelled, the error :const:`~gi.repository.Gio.IOErrorEnum.CANCELLED` will be returned.






      :param offset: a :obj:`~gi.repository.gint64`\.

      :param type: a :obj:`~gi.repository.GLib.SeekType`\.

      :param cancellable: optional :obj:`~gi.repository.Gio.Cancellable` object, :const:`None` to ignore.




   .. method:: do_tell() -> int

      Tells the current position within the stream.









   .. method:: do_truncate_fn(offset: int, cancellable: ~gi.repository.Gio.Cancellable | None = None) -> bool

      The type of the None singleton.







      :param offset: new length for ``seekable``\, in bytes.

      :param cancellable: optional :obj:`~gi.repository.Gio.Cancellable` object, :const:`None` to ignore.