tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1.. -*- coding: utf-8; mode: rst -*-
2
3.. _dmx_fread:
4
5=======================
6Digital TV demux read()
7=======================
8
9Name
10----
11
12Digital TV demux read()
13
14
15Synopsis
16--------
17
18.. c:function:: size_t read(int fd, void *buf, size_t count)
19 :name: dvb-dmx-read
20
21Arguments
22---------
23
24``fd``
25 File descriptor returned by a previous call to :c:func:`open() <dvb-ca-open>`.
26
27 ``buf``
28 Buffer to be filled
29
30``count``
31 Max number of bytes to read
32
33Description
34-----------
35
36This system call returns filtered data, which might be section or Packetized
37Elementary Stream (PES) data. The filtered data is transferred from
38the driver’s internal circular buffer to ``buf``. The maximum amount of data
39to be transferred is implied by count.
40
41.. note::
42
43 if a section filter created with
44 :c:type:`DMX_CHECK_CRC <dmx_sct_filter_params>` flag set,
45 data that fails on CRC check will be silently ignored.
46
47
48Return Value
49------------
50
51On success 0 is returned.
52
53On error -1 is returned, and the ``errno`` variable is set
54appropriately.
55
56.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
57
58.. flat-table::
59 :header-rows: 0
60 :stub-columns: 0
61 :widths: 1 16
62
63 - - ``EWOULDBLOCK``
64 - No data to return and ``O_NONBLOCK`` was specified.
65
66 - - ``EOVERFLOW``
67 - The filtered data was not read from the buffer in due time,
68 resulting in non-read data being lost. The buffer is flushed.
69
70 - - ``ETIMEDOUT``
71 - The section was not loaded within the stated timeout period.
72 See ioctl :ref:`DMX_SET_FILTER` for how to set a timeout.
73
74 - - ``EFAULT``
75 - The driver failed to write to the callers buffer due to an
76 invalid \*buf pointer.
77
78
79The generic error codes are described at the
80:ref:`Generic Error Codes <gen-errors>` chapter.