cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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dmx-fwrite.rst (1804B)


      1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
      2.. c:namespace:: DTV.dmx
      3
      4.. _dmx_fwrite:
      5
      6========================
      7Digital TV demux write()
      8========================
      9
     10Name
     11----
     12
     13Digital TV demux write()
     14
     15Synopsis
     16--------
     17
     18.. c:function:: ssize_t write(int fd, const void *buf, size_t count)
     19
     20Arguments
     21---------
     22
     23``fd``
     24  File descriptor returned by a previous call to :c:func:`open()`.
     25
     26``buf``
     27     Buffer with data to be written
     28
     29``count``
     30    Number of bytes at the buffer
     31
     32Description
     33-----------
     34
     35This system call is only provided by the logical device
     36``/dev/dvb/adapter?/dvr?``, associated with the physical demux device that
     37provides the actual DVR functionality. It is used for replay of a
     38digitally recorded Transport Stream. Matching filters have to be defined
     39in the corresponding physical demux device, ``/dev/dvb/adapter?/demux?``.
     40The amount of data to be transferred is implied by count.
     41
     42Return Value
     43------------
     44
     45On success 0 is returned.
     46
     47On error -1 is returned, and the ``errno`` variable is set
     48appropriately.
     49
     50.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
     51
     52.. flat-table::
     53    :header-rows:  0
     54    :stub-columns: 0
     55    :widths: 1 16
     56
     57    -  -  ``EWOULDBLOCK``
     58       -  No data was written. This might happen if ``O_NONBLOCK`` was
     59	  specified and there is no more buffer space available (if
     60	  ``O_NONBLOCK`` is not specified the function will block until buffer
     61	  space is available).
     62
     63    -  -  ``EBUSY``
     64       -  This error code indicates that there are conflicting requests. The
     65	  corresponding demux device is setup to receive data from the
     66	  front- end. Make sure that these filters are stopped and that the
     67	  filters with input set to ``DMX_IN_DVR`` are started.
     68
     69The generic error codes are described at the
     70:ref:`Generic Error Codes <gen-errors>` chapter.