.. 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 ``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() ` 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 ` 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.