xref: /OK3568_Linux_fs/kernel/Documentation/userspace-api/media/dvb/dmx-fwrite.rst (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593Smuzhiyun.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2*4882a593Smuzhiyun.. c:namespace:: DTV.dmx
3*4882a593Smuzhiyun
4*4882a593Smuzhiyun.. _dmx_fwrite:
5*4882a593Smuzhiyun
6*4882a593Smuzhiyun========================
7*4882a593SmuzhiyunDigital TV demux write()
8*4882a593Smuzhiyun========================
9*4882a593Smuzhiyun
10*4882a593SmuzhiyunName
11*4882a593Smuzhiyun----
12*4882a593Smuzhiyun
13*4882a593SmuzhiyunDigital TV demux write()
14*4882a593Smuzhiyun
15*4882a593SmuzhiyunSynopsis
16*4882a593Smuzhiyun--------
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun.. c:function:: ssize_t write(int fd, const void *buf, size_t count)
19*4882a593Smuzhiyun
20*4882a593SmuzhiyunArguments
21*4882a593Smuzhiyun---------
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun``fd``
24*4882a593Smuzhiyun  File descriptor returned by a previous call to :c:func:`open()`.
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun``buf``
27*4882a593Smuzhiyun     Buffer with data to be written
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun``count``
30*4882a593Smuzhiyun    Number of bytes at the buffer
31*4882a593Smuzhiyun
32*4882a593SmuzhiyunDescription
33*4882a593Smuzhiyun-----------
34*4882a593Smuzhiyun
35*4882a593SmuzhiyunThis system call is only provided by the logical device
36*4882a593Smuzhiyun``/dev/dvb/adapter?/dvr?``, associated with the physical demux device that
37*4882a593Smuzhiyunprovides the actual DVR functionality. It is used for replay of a
38*4882a593Smuzhiyundigitally recorded Transport Stream. Matching filters have to be defined
39*4882a593Smuzhiyunin the corresponding physical demux device, ``/dev/dvb/adapter?/demux?``.
40*4882a593SmuzhiyunThe amount of data to be transferred is implied by count.
41*4882a593Smuzhiyun
42*4882a593SmuzhiyunReturn Value
43*4882a593Smuzhiyun------------
44*4882a593Smuzhiyun
45*4882a593SmuzhiyunOn success 0 is returned.
46*4882a593Smuzhiyun
47*4882a593SmuzhiyunOn error -1 is returned, and the ``errno`` variable is set
48*4882a593Smuzhiyunappropriately.
49*4882a593Smuzhiyun
50*4882a593Smuzhiyun.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun.. flat-table::
53*4882a593Smuzhiyun    :header-rows:  0
54*4882a593Smuzhiyun    :stub-columns: 0
55*4882a593Smuzhiyun    :widths: 1 16
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun    -  -  ``EWOULDBLOCK``
58*4882a593Smuzhiyun       -  No data was written. This might happen if ``O_NONBLOCK`` was
59*4882a593Smuzhiyun	  specified and there is no more buffer space available (if
60*4882a593Smuzhiyun	  ``O_NONBLOCK`` is not specified the function will block until buffer
61*4882a593Smuzhiyun	  space is available).
62*4882a593Smuzhiyun
63*4882a593Smuzhiyun    -  -  ``EBUSY``
64*4882a593Smuzhiyun       -  This error code indicates that there are conflicting requests. The
65*4882a593Smuzhiyun	  corresponding demux device is setup to receive data from the
66*4882a593Smuzhiyun	  front- end. Make sure that these filters are stopped and that the
67*4882a593Smuzhiyun	  filters with input set to ``DMX_IN_DVR`` are started.
68*4882a593Smuzhiyun
69*4882a593SmuzhiyunThe generic error codes are described at the
70*4882a593Smuzhiyun:ref:`Generic Error Codes <gen-errors>` chapter.
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