systemd/docs/libudev/html/libudev-udev.html
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<a href="#libudev-udev.synopsis" class="shortcut">Top</a>
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<a href="#libudev-udev.description" class="shortcut">Description</a>
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<div class="refentry">
<a name="libudev-udev"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
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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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<td valign="top" align="right"></td>
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<div class="refsynopsisdiv">
<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>);
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-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_fn) (struct 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>);
<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">
<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">
<a name="libudev-udev.details"></a><h2>Details</h2>
<div class="refsect2">
<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">
<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" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<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">
<a name="udev-unref"></a><h3>udev_unref ()</h3>
<pre class="programlisting">struct <a class="link" href="libudev-udev.html#udev" title="struct udev"><span class="returnvalue">udev</span></a> * 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" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<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 if it has still an active reference, or <span class="type">NULL</span> otherwise.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<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" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<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">
<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_fn) (struct 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" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<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>log_fn</code></em> :</span></p></td>
<td>function to be called for logging messages</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<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" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<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">
<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" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<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">
<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" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<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">
<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" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<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>
</div>
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