1 .. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later 2 .. c:namespace:: MC 3 4 .. _request-func-ioctl: 5 6 *************** 7 request ioctl() 8 *************** 9 10 Name 11 ==== 12 13 request-ioctl - Control a request file descriptor 14 15 Synopsis 16 ======== 17 18 .. code-block:: c 19 20 #include <sys/ioctl.h> 21 22 ``int ioctl(int fd, int cmd, void *argp)`` 23 24 Arguments 25 ========= 26 27 ``fd`` 28 File descriptor returned by :ref:`MEDIA_IOC_REQUEST_ALLOC`. 29 30 ``cmd`` 31 The request ioctl command code as defined in the media.h header file, for 32 example :ref:`MEDIA_REQUEST_IOC_QUEUE`. 33 34 ``argp`` 35 Pointer to a request-specific structure. 36 37 Description 38 =========== 39 40 The :ref:`ioctl() <request-func-ioctl>` function manipulates request 41 parameters. The argument ``fd`` must be an open file descriptor. 42 43 The ioctl ``cmd`` code specifies the request function to be called. It 44 has encoded in it whether the argument is an input, output or read/write 45 parameter, and the size of the argument ``argp`` in bytes. 46 47 Macros and structures definitions specifying request ioctl commands and 48 their parameters are located in the media.h header file. All request ioctl 49 commands, their respective function and parameters are specified in 50 :ref:`media-user-func`. 51 52 Return Value 53 ============ 54 55 On success 0 is returned, on error -1 and the ``errno`` variable is set 56 appropriately. The generic error codes are described at the 57 :ref:`Generic Error Codes <gen-errors>` chapter. 58 59 Command-specific error codes are listed in the individual command 60 descriptions. 61 62 When an ioctl that takes an output or read/write parameter fails, the 63 parameter remains unmodified.
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.