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                  <a href="#libudev-udev.description" class="shortcut">Description</a>
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<div class="refentry" title="udev">
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<h2><span class="refentrytitle"><a name="libudev-udev.top_of_page"></a>udev</span></h2>
<p>udev — libudev context</p>
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<div class="refsynopsisdiv" title="Synopsis">
<a name="libudev-udev.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis">struct              <a class="link" href="libudev-udev.html#udev" title="struct udev">udev</a>;
struct <a class="link" href="libudev-udev.html#udev" title="struct udev"><span class="returnvalue">udev</span></a> *       <a class="link" href="libudev-udev.html#udev-ref" title="udev_ref ()">udev_ref</a>                            (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);
<span class="returnvalue">void</span>                <a class="link" href="libudev-udev.html#udev-unref" title="udev_unref ()">udev_unref</a>                          (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);
struct <a class="link" href="libudev-udev.html#udev" title="struct udev"><span class="returnvalue">udev</span></a> *       <a class="link" href="libudev-udev.html#udev-new" title="udev_new ()">udev_new</a>                            (<em class="parameter"><code><span class="type">void</span></code></em>);
<span class="returnvalue">void</span>                <a class="link" href="libudev-udev.html#udev-set-log-fn" title="udev_set_log_fn ()">udev_set_log_fn</a>                     (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>,
                                                         <em class="parameter"><code><span class="type">void</span> (log_fnstruct udev *udev, int priority, const char *file, int line, const char *fn, const char *format, va_list args) ()</code></em>);
<span class="returnvalue">int</span>                 <a class="link" href="libudev-udev.html#udev-get-log-priority" title="udev_get_log_priority ()">udev_get_log_priority</a>               (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);
<span class="returnvalue">void</span>                <a class="link" href="libudev-udev.html#udev-set-log-priority" title="udev_set_log_priority ()">udev_set_log_priority</a>               (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>,
                                                         <em class="parameter"><code><span class="type">int</span> priority</code></em>);
const <span class="returnvalue">char</span> *        <a class="link" href="libudev-udev.html#udev-get-sys-path" title="udev_get_sys_path ()">udev_get_sys_path</a>                   (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);
const <span class="returnvalue">char</span> *        <a class="link" href="libudev-udev.html#udev-get-dev-path" title="udev_get_dev_path ()">udev_get_dev_path</a>                   (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);
<span class="returnvalue">void</span> *              <a class="link" href="libudev-udev.html#udev-get-userdata" title="udev_get_userdata ()">udev_get_userdata</a>                   (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);
<span class="returnvalue">void</span>                <a class="link" href="libudev-udev.html#udev-set-userdata" title="udev_set_userdata ()">udev_set_userdata</a>                   (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>,
                                                         <em class="parameter"><code><span class="type">void</span> *userdata</code></em>);
</pre>
</div>
<div class="refsect1" title="Description">
<a name="libudev-udev.description"></a><h2>Description</h2>
<p>
The context contains the default values read from the udev config file,
and is passed to all library operations.
</p>
</div>
<div class="refsect1" title="Details">
<a name="libudev-udev.details"></a><h2>Details</h2>
<div class="refsect2" title="struct udev">
<a name="udev"></a><h3>struct udev</h3>
<pre class="programlisting">struct udev;</pre>
<p>
Opaque object representing the library context.
</p>
</div>
<hr>
<div class="refsect2" title="udev_ref ()">
<a name="udev-ref"></a><h3>udev_ref ()</h3>
<pre class="programlisting">struct <a class="link" href="libudev-udev.html#udev" title="struct udev"><span class="returnvalue">udev</span></a> *       udev_ref                            (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);</pre>
<p>
Take a reference of the udev library context.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>udev</code></em> :</span></p></td>
<td>udev library context
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the passed udev library context
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="udev_unref ()">
<a name="udev-unref"></a><h3>udev_unref ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                udev_unref                          (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);</pre>
<p>
Drop a reference of the udev library context. If the refcount
reaches zero, the resources of the context will be released.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>udev</code></em> :</span></p></td>
<td>udev library context
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="udev_new ()">
<a name="udev-new"></a><h3>udev_new ()</h3>
<pre class="programlisting">struct <a class="link" href="libudev-udev.html#udev" title="struct udev"><span class="returnvalue">udev</span></a> *       udev_new                            (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>
Create udev library context. This reads the udev configuration
file, and fills in the default values.
</p>
<p>
The initial refcount is 1, and needs to be decremented to
release the resources of the udev library context.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> a new udev library context
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="udev_set_log_fn ()">
<a name="udev-set-log-fn"></a><h3>udev_set_log_fn ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                udev_set_log_fn                     (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>,
                                                         <em class="parameter"><code><span class="type">void</span> (log_fnstruct udev *udev, int priority, const char *file, int line, const char *fn, const char *format, va_list args) ()</code></em>);</pre>
<p>
The built-in logging writes to stderr. It can be
overridden by a custom function, to plug log messages
into the users' logging functionality.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>udev</code></em> :</span></p></td>
<td>udev library context
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="udev_get_log_priority ()">
<a name="udev-get-log-priority"></a><h3>udev_get_log_priority ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>                 udev_get_log_priority               (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);</pre>
<p>
The initial logging priority is read from the udev config file
at startup.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>udev</code></em> :</span></p></td>
<td>udev library context
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the current logging priority
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="udev_set_log_priority ()">
<a name="udev-set-log-priority"></a><h3>udev_set_log_priority ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                udev_set_log_priority               (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>,
                                                         <em class="parameter"><code><span class="type">int</span> priority</code></em>);</pre>
<p>
Set the current logging priority. The value controls which messages
are logged.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>udev</code></em> :</span></p></td>
<td>udev library context
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>priority</code></em> :</span></p></td>
<td>the new logging priority
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="udev_get_sys_path ()">
<a name="udev-get-sys-path"></a><h3>udev_get_sys_path ()</h3>
<pre class="programlisting">const <span class="returnvalue">char</span> *        udev_get_sys_path                   (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);</pre>
<p>
Retrieve the sysfs mount point. The default is "/sys". For
testing purposes, it can be overridden with the environment
variable SYSFS_PATH.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>udev</code></em> :</span></p></td>
<td>udev library context
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the sys mount point
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="udev_get_dev_path ()">
<a name="udev-get-dev-path"></a><h3>udev_get_dev_path ()</h3>
<pre class="programlisting">const <span class="returnvalue">char</span> *        udev_get_dev_path                   (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);</pre>
<p>
Retrieve the device directory path. The default value is "/dev",
the actual value may be overridden in the udev configuration
file.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>udev</code></em> :</span></p></td>
<td>udev library context
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the device directory path
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="udev_get_userdata ()">
<a name="udev-get-userdata"></a><h3>udev_get_userdata ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> *              udev_get_userdata                   (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>);</pre>
<p>
Retrieve stored data pointer from library context. This might be useful
to access from callbacks like a custom logging function.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>udev</code></em> :</span></p></td>
<td>udev library context
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> stored userdata
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="udev_set_userdata ()">
<a name="udev-set-userdata"></a><h3>udev_set_userdata ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>                udev_set_userdata                   (<em class="parameter"><code><span class="type">struct udev</span> *udev</code></em>,
                                                         <em class="parameter"><code><span class="type">void</span> *userdata</code></em>);</pre>
<p>
Store custom <em class="parameter"><code>userdata</code></em> in the library context.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>udev</code></em> :</span></p></td>
<td>udev library context
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>userdata</code></em> :</span></p></td>
<td>data pointer
</td>
</tr>
</tbody>
</table></div>
</div>
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