.. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later .. c:namespace:: MC

.. _request-func-ioctl:

request ioctl()

Name

request-ioctl - Control a request file descriptor

Synopsis

.. code-block:: c

#include <sys/ioctl.h>

int ioctl(int fd, int cmd, void *argp)

Arguments

fd File descriptor returned by :ref:MEDIA_IOC_REQUEST_ALLOC.

cmd The request ioctl command code as defined in the media.h header file, for example :ref:MEDIA_REQUEST_IOC_QUEUE.

argp Pointer to a request-specific structure.

Description

The :ref:ioctl() <request-func-ioctl> function manipulates request parameters. The argument fd must be an open file descriptor.

The ioctl cmd code specifies the request 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 request ioctl commands and their parameters are located in the media.h header file. All request ioctl commands, their respective function and parameters are specified in :ref:media-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.

Command-specific error codes are listed in the individual command descriptions.

When an ioctl that takes an output or read/write parameter fails, the parameter remains unmodified.