1 .. SPDX-License-Identifier: GFDL-1.1-no-invari 1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2 .. c:namespace:: CEC 2 .. c:namespace:: CEC
3 3
4 .. _cec-func-poll: 4 .. _cec-func-poll:
5 5
6 ********** 6 **********
7 cec poll() 7 cec poll()
8 ********** 8 **********
9 9
10 Name 10 Name
11 ==== 11 ====
12 12
13 cec-poll - Wait for some event on a file descr 13 cec-poll - Wait for some event on a file descriptor
14 14
15 Synopsis 15 Synopsis
16 ======== 16 ========
17 17
18 .. code-block:: c 18 .. code-block:: c
19 19
20 #include <sys/poll.h> 20 #include <sys/poll.h>
21 21
22 .. c:function:: int poll( struct pollfd *ufds, 22 .. c:function:: int poll( struct pollfd *ufds, unsigned int nfds, int timeout )
23 23
24 Arguments 24 Arguments
25 ========= 25 =========
26 26
27 ``ufds`` 27 ``ufds``
28 List of FD events to be watched 28 List of FD events to be watched
29 29
30 ``nfds`` 30 ``nfds``
31 Number of FD events at the \*ufds array 31 Number of FD events at the \*ufds array
32 32
33 ``timeout`` 33 ``timeout``
34 Timeout to wait for events 34 Timeout to wait for events
35 35
36 Description 36 Description
37 =========== 37 ===========
38 38
39 With the :c:func:`poll()` function application 39 With the :c:func:`poll()` function applications can wait for CEC
40 events. 40 events.
41 41
42 On success :c:func:`poll()` returns the number 42 On success :c:func:`poll()` returns the number of file descriptors
43 that have been selected (that is, file descrip 43 that have been selected (that is, file descriptors for which the
44 ``revents`` field of the respective struct :c: 44 ``revents`` field of the respective struct :c:type:`pollfd`
45 is non-zero). CEC devices set the ``POLLIN`` a 45 is non-zero). CEC devices set the ``POLLIN`` and ``POLLRDNORM`` flags in
46 the ``revents`` field if there are messages in 46 the ``revents`` field if there are messages in the receive queue. If the
47 transmit queue has room for new messages, the 47 transmit queue has room for new messages, the ``POLLOUT`` and
48 ``POLLWRNORM`` flags are set. If there are eve 48 ``POLLWRNORM`` flags are set. If there are events in the event queue,
49 then the ``POLLPRI`` flag is set. When the fun 49 then the ``POLLPRI`` flag is set. When the function times out it returns
50 a value of zero, on failure it returns -1 and 50 a value of zero, on failure it returns -1 and the ``errno`` variable is
51 set appropriately. 51 set appropriately.
52 52
53 For more details see the :c:func:`poll()` manu 53 For more details see the :c:func:`poll()` manual page.
54 54
55 Return Value 55 Return Value
56 ============ 56 ============
57 57
58 On success, :c:func:`poll()` returns the numbe 58 On success, :c:func:`poll()` returns the number structures which have
59 non-zero ``revents`` fields, or zero if the ca 59 non-zero ``revents`` fields, or zero if the call timed out. On error -1
60 is returned, and the ``errno`` variable is set 60 is returned, and the ``errno`` variable is set appropriately:
61 61
62 ``EBADF`` 62 ``EBADF``
63 One or more of the ``ufds`` members specif 63 One or more of the ``ufds`` members specify an invalid file
64 descriptor. 64 descriptor.
65 65
66 ``EFAULT`` 66 ``EFAULT``
67 ``ufds`` references an inaccessible memory 67 ``ufds`` references an inaccessible memory area.
68 68
69 ``EINTR`` 69 ``EINTR``
70 The call was interrupted by a signal. 70 The call was interrupted by a signal.
71 71
72 ``EINVAL`` 72 ``EINVAL``
73 The ``nfds`` value exceeds the ``RLIMIT_NO 73 The ``nfds`` value exceeds the ``RLIMIT_NOFILE`` value. Use
74 ``getrlimit()`` to obtain this value. 74 ``getrlimit()`` to obtain this value.
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