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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/Documentation/DocBook/v4l/media-func-open.xml
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<refentry id="media-func-open">

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  <refmeta>

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    <refentrytitle>media open()</refentrytitle>

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    &manvol;

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  </refmeta>

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  <refnamediv>

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    <refname>media-open</refname>

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    <refpurpose>Open a media device</refpurpose>

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  </refnamediv>

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  <refsynopsisdiv>

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    <funcsynopsis>

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      <funcsynopsisinfo>#include &lt;fcntl.h&gt;</funcsynopsisinfo>

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      <funcprototype>

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	<funcdef>int <function>open</function></funcdef>

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	<paramdef>const char *<parameter>device_name</parameter></paramdef>

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	<paramdef>int <parameter>flags</parameter></paramdef>

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      </funcprototype>

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    </funcsynopsis>

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  </refsynopsisdiv>

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  <refsect1>

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    <title>Arguments</title>

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    <variablelist>

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      <varlistentry>

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	<term><parameter>device_name</parameter></term>

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	<listitem>

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	  <para>Device to be opened.</para>

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	</listitem>

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      </varlistentry>

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      <varlistentry>

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	<term><parameter>flags</parameter></term>

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	<listitem>

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	  <para>Open flags. Access mode must be either <constant>O_RDONLY</constant>

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	  or <constant>O_RDWR</constant>. Other flags have no effect.</para>

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	</listitem>

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      </varlistentry>

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    </variablelist>

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  </refsect1>

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  <refsect1>

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    <title>Description</title>

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    <para>To open a media device applications call <function>open()</function>

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    with the desired device name. The function has no side effects; the device

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    configuration remain unchanged.</para>

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    <para>When the device is opened in read-only mode, attemps to modify its

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    configuration will result in an error, and <varname>errno</varname> will be

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    set to <errorcode>EBADF</errorcode>.</para>

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  </refsect1>

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  <refsect1>

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    <title>Return Value</title>

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    <para><function>open</function> returns the new file descriptor on success.

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    On error, -1 is returned, and <varname>errno</varname> is set appropriately.

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    Possible error codes are:</para>

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    <variablelist>

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      <varlistentry>

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	<term><errorcode>EACCES</errorcode></term>

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	<listitem>

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	  <para>The requested access to the file is not allowed.</para>

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	</listitem>

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      </varlistentry>

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      <varlistentry>

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	<term><errorcode>EMFILE</errorcode></term>

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	<listitem>

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	  <para>The  process  already  has  the  maximum number of files open.

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	  </para>

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	</listitem>

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      </varlistentry>

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      <varlistentry>

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	<term><errorcode>ENFILE</errorcode></term>

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	<listitem>

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	  <para>The system limit on the total number of open files has been

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	  reached.</para>

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	</listitem>

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      </varlistentry>

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      <varlistentry>

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	<term><errorcode>ENOMEM</errorcode></term>

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	<listitem>

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	  <para>Insufficient kernel memory was available.</para>

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	</listitem>

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      </varlistentry>

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      <varlistentry>

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	<term><errorcode>ENXIO</errorcode></term>

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	<listitem>

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	  <para>No device corresponding to this device special file exists.

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	  </para>

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	</listitem>

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      </varlistentry>

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    </variablelist>

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  </refsect1>

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</refentry>

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