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1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: CEC3 4.. _cec-func-poll:5 6**********7cec poll()8**********9 10Name11====12 13cec-poll - Wait for some event on a file descriptor14 15Synopsis16========17 18.. code-block:: c19 20 #include <sys/poll.h>21 22.. c:function:: int poll( struct pollfd *ufds, unsigned int nfds, int timeout )23 24Arguments25=========26 27``ufds``28 List of FD events to be watched29 30``nfds``31 Number of FD events at the \*ufds array32 33``timeout``34 Timeout to wait for events35 36Description37===========38 39With the :c:func:`poll()` function applications can wait for CEC40events.41 42On success :c:func:`poll()` returns the number of file descriptors43that have been selected (that is, file descriptors for which the44``revents`` field of the respective struct :c:type:`pollfd`45is non-zero). CEC devices set the ``POLLIN`` and ``POLLRDNORM`` flags in46the ``revents`` field if there are messages in the receive queue. If the47transmit queue has room for new messages, the ``POLLOUT`` and48``POLLWRNORM`` flags are set. If there are events in the event queue,49then the ``POLLPRI`` flag is set. When the function times out it returns50a value of zero, on failure it returns -1 and the ``errno`` variable is51set appropriately.52 53For more details see the :c:func:`poll()` manual page.54 55Return Value56============57 58On success, :c:func:`poll()` returns the number structures which have59non-zero ``revents`` fields, or zero if the call timed out. On error -160is returned, and the ``errno`` variable is set appropriately:61 62``EBADF``63 One or more of the ``ufds`` members specify an invalid file64 descriptor.65 66``EFAULT``67 ``ufds`` references an inaccessible memory area.68 69``EINTR``70 The call was interrupted by a signal.71 72``EINVAL``73 The ``nfds`` value exceeds the ``RLIMIT_NOFILE`` value. Use74 ``getrlimit()`` to obtain this value.75