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- .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
- .. c:namespace:: MC
- .. _media-func-ioctl:
- *************
- media ioctl()
- *************
- Name
- ====
- media-ioctl - Control a media device
- Synopsis
- ========
- .. code-block:: c
- #include <sys/ioctl.h>
- ``int ioctl(int fd, int request, void *argp)``
- Arguments
- =========
- ``fd``
- File descriptor returned by :c:func:`open()`.
- ``request``
- Media ioctl request code as defined in the media.h header file, for
- example MEDIA_IOC_SETUP_LINK.
- ``argp``
- Pointer to a request-specific structure.
- Description
- ===========
- The :ref:`ioctl() <media-func-ioctl>` function manipulates media device
- parameters. The argument ``fd`` must be an open file descriptor.
- The ioctl ``request`` code specifies the media 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 media ioctl requests and
- their parameters are located in the media.h header file. All media ioctl
- requests, 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.
- 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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