mirror of https://gitee.com/openkylin/linux.git
75 lines
2.1 KiB
ReStructuredText
75 lines
2.1 KiB
ReStructuredText
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.. -*- coding: utf-8; mode: rst -*-
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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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*man cec-poll(2)*
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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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Description
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===========
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Note: this documents the proposed CEC API. This API is not yet finalized
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and is currently only available as a staging kernel module.
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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 :c:type:`struct pollfd` structure
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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 timed 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`` argument is greater than ``OPEN_MAX``.
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.. ------------------------------------------------------------------------------
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.. This file was automatically converted from DocBook-XML with the dbxml
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.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
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.. from the linux kernel, refer to:
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..
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.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
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.. ------------------------------------------------------------------------------
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