.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. c:namespace:: CEC
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.. _cec-func-poll:
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**********
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cec poll()
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**********
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Name
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====
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cec-poll - Wait for some event on a file descriptor
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Synopsis
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========
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.. code-block:: c
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#include <sys/poll.h>
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.. c:function:: int poll( struct pollfd *ufds, unsigned int nfds, int timeout )
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Arguments
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=========
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``ufds``
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List of FD events to be watched
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``nfds``
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Number of FD events at the \*ufds array
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``timeout``
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Timeout to wait for events
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Description
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===========
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With the :c:func:`poll()` function applications can wait for CEC
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events.
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On success :c:func:`poll()` returns the number of file descriptors
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that have been selected (that is, file descriptors for which the
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``revents`` field of the respective struct :c:type:`pollfd`
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is non-zero). CEC devices set the ``POLLIN`` and ``POLLRDNORM`` flags in
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the ``revents`` field if there are messages in the receive queue. If the
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transmit queue has room for new messages, the ``POLLOUT`` and
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``POLLWRNORM`` flags are set. If there are events in the event queue,
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then the ``POLLPRI`` flag is set. When the function times out it returns
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a value of zero, on failure it returns -1 and the ``errno`` variable is
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set appropriately.
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For more details see the :c:func:`poll()` manual page.
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Return Value
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============
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On success, :c:func:`poll()` returns the number structures which have
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non-zero ``revents`` fields, or zero if the call timed out. On error -1
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is returned, and the ``errno`` variable is set appropriately:
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``EBADF``
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One or more of the ``ufds`` members specify an invalid file
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descriptor.
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``EFAULT``
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``ufds`` references an inaccessible memory area.
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``EINTR``
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The call was interrupted by a signal.
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``EINVAL``
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The ``nfds`` value exceeds the ``RLIMIT_NOFILE`` value. Use
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``getrlimit()`` to obtain this value.
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