ubuntu-linux-kernel/Documentation/media/uapi/dvb/dmx-fwrite.rst

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.. -*- coding: utf-8; mode: rst -*-
.. _dmx_fwrite:
========================
Digital TV demux write()
========================
Name
----
Digital TV demux write()
Synopsis
--------
.. c:function:: ssize_t write(int fd, const void *buf, size_t count)
:name: dvb-dmx-write
Arguments
---------
``fd``
File descriptor returned by a previous call to :c:func:`open() <dvb-ca-open>`.
``buf``
Buffer with data to be written
``count``
Number of bytes at the buffer
Description
-----------
This system call is only provided by the logical device
``/dev/dvb/adapter?/dvr?``, associated with the physical demux device that
provides the actual DVR functionality. It is used for replay of a
digitally recorded Transport Stream. Matching filters have to be defined
in the corresponding physical demux device, ``/dev/dvb/adapter?/demux?``.
The amount of data to be transferred is implied by count.
Return Value
------------
On success 0 is returned.
On error -1 is returned, and the ``errno`` variable is set
appropriately.
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- - ``EWOULDBLOCK``
- No data was written. This might happen if ``O_NONBLOCK`` was
specified and there is no more buffer space available (if
``O_NONBLOCK`` is not specified the function will block until buffer
space is available).
- - ``EBUSY``
- This error code indicates that there are conflicting requests. The
corresponding demux device is setup to receive data from the
front- end. Make sure that these filters are stopped and that the
filters with input set to ``DMX_IN_DVR`` are started.
The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.