162306a36Sopenharmony_ci.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 262306a36Sopenharmony_ci.. c:namespace:: CEC 362306a36Sopenharmony_ci 462306a36Sopenharmony_ci.. _cec-func-poll: 562306a36Sopenharmony_ci 662306a36Sopenharmony_ci********** 762306a36Sopenharmony_cicec poll() 862306a36Sopenharmony_ci********** 962306a36Sopenharmony_ci 1062306a36Sopenharmony_ciName 1162306a36Sopenharmony_ci==== 1262306a36Sopenharmony_ci 1362306a36Sopenharmony_cicec-poll - Wait for some event on a file descriptor 1462306a36Sopenharmony_ci 1562306a36Sopenharmony_ciSynopsis 1662306a36Sopenharmony_ci======== 1762306a36Sopenharmony_ci 1862306a36Sopenharmony_ci.. code-block:: c 1962306a36Sopenharmony_ci 2062306a36Sopenharmony_ci #include <sys/poll.h> 2162306a36Sopenharmony_ci 2262306a36Sopenharmony_ci.. c:function:: int poll( struct pollfd *ufds, unsigned int nfds, int timeout ) 2362306a36Sopenharmony_ci 2462306a36Sopenharmony_ciArguments 2562306a36Sopenharmony_ci========= 2662306a36Sopenharmony_ci 2762306a36Sopenharmony_ci``ufds`` 2862306a36Sopenharmony_ci List of FD events to be watched 2962306a36Sopenharmony_ci 3062306a36Sopenharmony_ci``nfds`` 3162306a36Sopenharmony_ci Number of FD events at the \*ufds array 3262306a36Sopenharmony_ci 3362306a36Sopenharmony_ci``timeout`` 3462306a36Sopenharmony_ci Timeout to wait for events 3562306a36Sopenharmony_ci 3662306a36Sopenharmony_ciDescription 3762306a36Sopenharmony_ci=========== 3862306a36Sopenharmony_ci 3962306a36Sopenharmony_ciWith the :c:func:`poll()` function applications can wait for CEC 4062306a36Sopenharmony_cievents. 4162306a36Sopenharmony_ci 4262306a36Sopenharmony_ciOn success :c:func:`poll()` returns the number of file descriptors 4362306a36Sopenharmony_cithat have been selected (that is, file descriptors for which the 4462306a36Sopenharmony_ci``revents`` field of the respective struct :c:type:`pollfd` 4562306a36Sopenharmony_ciis non-zero). CEC devices set the ``POLLIN`` and ``POLLRDNORM`` flags in 4662306a36Sopenharmony_cithe ``revents`` field if there are messages in the receive queue. If the 4762306a36Sopenharmony_citransmit queue has room for new messages, the ``POLLOUT`` and 4862306a36Sopenharmony_ci``POLLWRNORM`` flags are set. If there are events in the event queue, 4962306a36Sopenharmony_cithen the ``POLLPRI`` flag is set. When the function times out it returns 5062306a36Sopenharmony_cia value of zero, on failure it returns -1 and the ``errno`` variable is 5162306a36Sopenharmony_ciset appropriately. 5262306a36Sopenharmony_ci 5362306a36Sopenharmony_ciFor more details see the :c:func:`poll()` manual page. 5462306a36Sopenharmony_ci 5562306a36Sopenharmony_ciReturn Value 5662306a36Sopenharmony_ci============ 5762306a36Sopenharmony_ci 5862306a36Sopenharmony_ciOn success, :c:func:`poll()` returns the number structures which have 5962306a36Sopenharmony_cinon-zero ``revents`` fields, or zero if the call timed out. On error -1 6062306a36Sopenharmony_ciis returned, and the ``errno`` variable is set appropriately: 6162306a36Sopenharmony_ci 6262306a36Sopenharmony_ci``EBADF`` 6362306a36Sopenharmony_ci One or more of the ``ufds`` members specify an invalid file 6462306a36Sopenharmony_ci descriptor. 6562306a36Sopenharmony_ci 6662306a36Sopenharmony_ci``EFAULT`` 6762306a36Sopenharmony_ci ``ufds`` references an inaccessible memory area. 6862306a36Sopenharmony_ci 6962306a36Sopenharmony_ci``EINTR`` 7062306a36Sopenharmony_ci The call was interrupted by a signal. 7162306a36Sopenharmony_ci 7262306a36Sopenharmony_ci``EINVAL`` 7362306a36Sopenharmony_ci The ``nfds`` value exceeds the ``RLIMIT_NOFILE`` value. Use 7462306a36Sopenharmony_ci ``getrlimit()`` to obtain this value. 75