| Laurent Pinchart | 140d881 | 2010-08-18 11:41:22 -0300 | [diff] [blame] | 1 | <refentry id="media-func-open"> |
| 2 | <refmeta> |
| 3 | <refentrytitle>media open()</refentrytitle> |
| 4 | &manvol; |
| 5 | </refmeta> |
| 6 | |
| 7 | <refnamediv> |
| 8 | <refname>media-open</refname> |
| 9 | <refpurpose>Open a media device</refpurpose> |
| 10 | </refnamediv> |
| 11 | |
| 12 | <refsynopsisdiv> |
| 13 | <funcsynopsis> |
| 14 | <funcsynopsisinfo>#include <fcntl.h></funcsynopsisinfo> |
| 15 | <funcprototype> |
| 16 | <funcdef>int <function>open</function></funcdef> |
| 17 | <paramdef>const char *<parameter>device_name</parameter></paramdef> |
| 18 | <paramdef>int <parameter>flags</parameter></paramdef> |
| 19 | </funcprototype> |
| 20 | </funcsynopsis> |
| 21 | </refsynopsisdiv> |
| 22 | |
| 23 | <refsect1> |
| 24 | <title>Arguments</title> |
| 25 | |
| 26 | <variablelist> |
| 27 | <varlistentry> |
| 28 | <term><parameter>device_name</parameter></term> |
| 29 | <listitem> |
| 30 | <para>Device to be opened.</para> |
| 31 | </listitem> |
| 32 | </varlistentry> |
| 33 | <varlistentry> |
| 34 | <term><parameter>flags</parameter></term> |
| 35 | <listitem> |
| 36 | <para>Open flags. Access mode must be either <constant>O_RDONLY</constant> |
| 37 | or <constant>O_RDWR</constant>. Other flags have no effect.</para> |
| 38 | </listitem> |
| 39 | </varlistentry> |
| 40 | </variablelist> |
| 41 | </refsect1> |
| 42 | <refsect1> |
| 43 | <title>Description</title> |
| 44 | <para>To open a media device applications call <function>open()</function> |
| 45 | with the desired device name. The function has no side effects; the device |
| 46 | configuration remain unchanged.</para> |
| 47 | <para>When the device is opened in read-only mode, attemps to modify its |
| 48 | configuration will result in an error, and <varname>errno</varname> will be |
| 49 | set to <errorcode>EBADF</errorcode>.</para> |
| 50 | </refsect1> |
| 51 | <refsect1> |
| 52 | <title>Return Value</title> |
| 53 | |
| 54 | <para><function>open</function> returns the new file descriptor on success. |
| 55 | On error, -1 is returned, and <varname>errno</varname> is set appropriately. |
| 56 | Possible error codes are:</para> |
| 57 | |
| 58 | <variablelist> |
| 59 | <varlistentry> |
| 60 | <term><errorcode>EACCES</errorcode></term> |
| 61 | <listitem> |
| 62 | <para>The requested access to the file is not allowed.</para> |
| 63 | </listitem> |
| 64 | </varlistentry> |
| 65 | <varlistentry> |
| 66 | <term><errorcode>EMFILE</errorcode></term> |
| 67 | <listitem> |
| 68 | <para>The process already has the maximum number of files open. |
| 69 | </para> |
| 70 | </listitem> |
| 71 | </varlistentry> |
| 72 | <varlistentry> |
| 73 | <term><errorcode>ENFILE</errorcode></term> |
| 74 | <listitem> |
| 75 | <para>The system limit on the total number of open files has been |
| 76 | reached.</para> |
| 77 | </listitem> |
| 78 | </varlistentry> |
| 79 | <varlistentry> |
| 80 | <term><errorcode>ENOMEM</errorcode></term> |
| 81 | <listitem> |
| 82 | <para>Insufficient kernel memory was available.</para> |
| 83 | </listitem> |
| 84 | </varlistentry> |
| 85 | <varlistentry> |
| 86 | <term><errorcode>ENXIO</errorcode></term> |
| 87 | <listitem> |
| 88 | <para>No device corresponding to this device special file exists. |
| 89 | </para> |
| 90 | </listitem> |
| 91 | </varlistentry> |
| 92 | </variablelist> |
| 93 | </refsect1> |
| 94 | </refentry> |