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.. _cec-func-ioctl:
***********
cec ioctl()
***********
Name
====
cec-ioctl - Control a cec device
Synopsis
========
.. code-block:: c
#include <sys/ioctl.h>
.. c:function:: int ioctl( int fd, int request, void *argp )
:name: cec-ioctl
Arguments
=========
``fd``
File descriptor returned by :c:func:`open() <cec-open>`.
``request``
CEC ioctl request code as defined in the cec.h header file, for
example :ref:`CEC_ADAP_G_CAPS <CEC_ADAP_G_CAPS>`.
``argp``
Pointer to a request-specific structure.
Description
===========
The :c:func:`ioctl() <cec-ioctl>` function manipulates cec device parameters. The
argument ``fd`` must be an open file descriptor.
The ioctl ``request`` code specifies the cec function to be called. It
has encoded in it whether the argument is an input, output or read/write
parameter, and the size of the argument ``argp`` in bytes.
Macros and structures definitions specifying cec ioctl requests and
their parameters are located in the cec.h header file. All cec ioctl
requests, their respective function and parameters are specified in
:ref:`cec-user-func`.
Return Value
============
On success 0 is returned, on error -1 and the ``errno`` variable is set
appropriately. The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.
Request-specific error codes are listed in the individual requests
descriptions.
When an ioctl that takes an output or read/write parameter fails, the
parameter remains unmodified.
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