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1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: DTV.dmx3 4.. _dmx_fwrite:5 6========================7Digital TV demux write()8========================9 10Name11----12 13Digital TV demux write()14 15Synopsis16--------17 18.. c:function:: ssize_t write(int fd, const void *buf, size_t count)19 20Arguments21---------22 23``fd``24 File descriptor returned by a previous call to :c:func:`open()`.25 26``buf``27 Buffer with data to be written28 29``count``30 Number of bytes at the buffer31 32Description33-----------34 35This system call is only provided by the logical device36``/dev/dvb/adapter?/dvr?``, associated with the physical demux device that37provides the actual DVR functionality. It is used for replay of a38digitally recorded Transport Stream. Matching filters have to be defined39in the corresponding physical demux device, ``/dev/dvb/adapter?/demux?``.40The amount of data to be transferred is implied by count.41 42Return Value43------------44 45On success 0 is returned.46 47On error -1 is returned, and the ``errno`` variable is set48appropriately.49 50.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|51 52.. flat-table::53 :header-rows: 054 :stub-columns: 055 :widths: 1 1656 57 - - ``EWOULDBLOCK``58 - No data was written. This might happen if ``O_NONBLOCK`` was59 specified and there is no more buffer space available (if60 ``O_NONBLOCK`` is not specified the function will block until buffer61 space is available).62 63 - - ``EBUSY``64 - This error code indicates that there are conflicting requests. The65 corresponding demux device is setup to receive data from the66 front- end. Make sure that these filters are stopped and that the67 filters with input set to ``DMX_IN_DVR`` are started.68 69The generic error codes are described at the70:ref:`Generic Error Codes <gen-errors>` chapter.71