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1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
3 | .. _media-func-ioctl: | |
4 | ||
5 | ************* | |
6 | media ioctl() | |
7 | ************* | |
8 | ||
15e7d615 | 9 | Name |
586027ce | 10 | ==== |
5377d91f | 11 | |
586027ce | 12 | media-ioctl - Control a media device |
5377d91f | 13 | |
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14 | |
15 | Synopsis | |
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16 | ======== |
17 | ||
18 | .. code-block:: c | |
19 | ||
20 | #include <sys/ioctl.h> | |
21 | ||
22 | ||
1b81f010 | 23 | .. c:function:: int ioctl( int fd, int request, void *argp ) |
5ccbb182 | 24 | :name: mc-ioctl |
586027ce | 25 | |
15e7d615 | 26 | Arguments |
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27 | ========= |
28 | ||
29 | ``fd`` | |
5ccbb182 | 30 | File descriptor returned by :c:func:`open() <mc-open>`. |
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31 | |
32 | ``request`` | |
33 | Media ioctl request code as defined in the media.h header file, for | |
34 | example MEDIA_IOC_SETUP_LINK. | |
35 | ||
36 | ``argp`` | |
37 | Pointer to a request-specific structure. | |
38 | ||
39 | ||
15e7d615 | 40 | Description |
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41 | =========== |
42 | ||
8c1cc62a MCC |
43 | The :ref:`ioctl() <media-func-ioctl>` function manipulates media device |
44 | parameters. The argument ``fd`` must be an open file descriptor. | |
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45 | |
46 | The ioctl ``request`` code specifies the media function to be called. It | |
47 | has encoded in it whether the argument is an input, output or read/write | |
48 | parameter, and the size of the argument ``argp`` in bytes. | |
49 | ||
50 | Macros and structures definitions specifying media ioctl requests and | |
51 | their parameters are located in the media.h header file. All media ioctl | |
52 | requests, their respective function and parameters are specified in | |
53 | :ref:`media-user-func`. | |
54 | ||
55 | ||
15e7d615 | 56 | Return Value |
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57 | ============ |
58 | ||
59 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
60 | appropriately. The generic error codes are described at the | |
61 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
62 | ||
63 | Request-specific error codes are listed in the individual requests | |
64 | descriptions. | |
65 | ||
66 | When an ioctl that takes an output or read/write parameter fails, the | |
67 | parameter remains unmodified. |