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<li class="toctree-l3 current"><a class="current reference internal" href="#">Logging</a><ul>
<li class="toctree-l4"><a class="reference internal" href="#priority-levels">Priority Levels</a></li>
<li class="toctree-l4"><a class="reference internal" href="#priority-mask">Priority mask</a></li>
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  <section id="logging">
<h1>Logging<a class="headerlink" href="#logging" title="Permalink to this heading"></a></h1>
<p>NuttX provides the SYSLOG for application and OS logging, which can be
configured in various ways to select how these messages are displayed
(see details <a class="reference internal" href="../../components/drivers/special/syslog.html"><span class="doc">here</span></a>).</p>
<p>Applications can emit logging messages using the standard <a class="reference internal" href="#c.syslog" title="syslog"><code class="xref c c-func docutils literal notranslate"><span class="pre">syslog()</span></code></a>
interface.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>The standard <code class="xref c c-func docutils literal notranslate"><span class="pre">openlog()</span></code> and <code class="xref c c-func docutils literal notranslate"><span class="pre">closelog()</span></code>
are not currently supported.</p>
</div>
<dl class="c function">
<dt class="sig sig-object c" id="c.syslog">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">syslog</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">priority</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">fmt</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.syslog" title="Permalink to this definition"></a><br /></dt>
<dd><p>This interface allows to send messages to SYSLOG using standard
<code class="xref c c-func docutils literal notranslate"><span class="pre">printf()</span></code> formatting.</p>
<p>Each message sent to SYSLOG is assigned a priority. Depending
on system configuration this message may or not appear in the
output.</p>
<dl class="field-list simple">
<dt class="field-odd">Parameters<span class="colon">:</span></dt>
<dd class="field-odd"><ul class="simple">
<li><p><strong>priority</strong> – A priority given by <code class="docutils literal notranslate"><span class="pre">LOG_*</span></code> family of
definitions.</p></li>
<li><p><strong>fmt</strong> – The format string</p></li>
</ul>
</dd>
</dl>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.vsyslog">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">vsyslog</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">priority</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">fmt</span></span>, <span class="n"><span class="pre">va_list</span></span><span class="w"> </span><span class="n"><span class="pre">ap</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.vsyslog" title="Permalink to this definition"></a><br /></dt>
<dd><p>Performs the same task as <a class="reference internal" href="#c.syslog" title="syslog"><code class="xref c c-func docutils literal notranslate"><span class="pre">syslog()</span></code></a> with the
difference that it takes a set of arguments which have been obtained
using the <code class="file docutils literal notranslate"><span class="pre">include/stdarg.h</span></code> variable argument list macros.</p>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.setlogmask">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">setlogmask</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">mask</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.setlogmask" title="Permalink to this definition"></a><br /></dt>
<dd><p>Sets the logging mask which controls which messages appear on SYSLOG
output. <a class="reference internal" href="#c.setlogmask" title="setlogmask"><code class="xref c c-func docutils literal notranslate"><span class="pre">setlogmask()</span></code></a> is not a thread-safe, re-entrant function.
Concurrent use will have undefined behavior.</p>
<dl class="field-list simple">
<dt class="field-odd">Parameters<span class="colon">:</span></dt>
<dd class="field-odd"><ul class="simple">
<li><p><strong>mask</strong> – The new mask to set.
See <a class="reference internal" href="#c.LOG_MASK" title="LOG_MASK"><code class="xref c c-macro docutils literal notranslate"><span class="pre">LOG_MASK</span></code></a> and <a class="reference internal" href="#c.LOG_UPTO" title="LOG_UPTO"><code class="xref c c-macro docutils literal notranslate"><span class="pre">LOG_UPTO</span></code></a>.
Per OpenGroup.org “If the maskpri argument is 0, the current log mask
is not modified.”  In this implementation, the value zero is permitted
in order to disable all syslog levels.</p></li>
</ul>
</dd>
<dt class="field-even">Returns<span class="colon">:</span></dt>
<dd class="field-even"><p>The previous mask.</p>
</dd>
</dl>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Per POSIX the syslog mask should be a per-process value but in
NuttX, the scope of the mask is dependent on the nature of the build:</p>
<ul class="simple">
<li><p>Flat Build:  There is one, global SYSLOG mask that controls all output.</p></li>
<li><p>Protected Build:  There are two SYSLOG masks.  One within the kernel
that controls only kernel output.  And one in user-space that controls
only user SYSLOG output.</p></li>
<li><p>Kernel Build:  The kernel build is compliant with the POSIX requirement:
There will be one mask for each user process, controlling the SYSLOG
output only form that process.  There will be a separate mask
accessible only in the kernel code to control kernel SYSLOG output.</p></li>
</ul>
</div>
</dd></dl>

<section id="priority-levels">
<h2>Priority Levels<a class="headerlink" href="#priority-levels" title="Permalink to this heading"></a></h2>
<p>The following levels are defined:</p>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Priority (macro)</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">LOG_EMERG</span></code></p></td>
<td><p>System is unusable</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">LOG_ALERT</span></code></p></td>
<td><p>Action must be taken immediately</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">LOG_CRIT</span></code></p></td>
<td><p>Critical conditions</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">LOG_ERR</span></code></p></td>
<td><p>Error conditions</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">LOG_WARNING</span></code></p></td>
<td><p>Warning conditions</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">LOG_NOTICE</span></code></p></td>
<td><p>Normal, but significant, condition</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">LOG_INFO</span></code></p></td>
<td><p>Informational message</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">LOG_DEBUG</span></code></p></td>
<td><p>Debug-level message</p></td>
</tr>
</tbody>
</table>
</section>
<section id="priority-mask">
<h2>Priority mask<a class="headerlink" href="#priority-mask" title="Permalink to this heading"></a></h2>
<p>The following macros can be used with <a class="reference internal" href="#c.setlogmask" title="setlogmask"><code class="xref c c-func docutils literal notranslate"><span class="pre">setlogmask()</span></code></a>:</p>
<dl class="c macro">
<dt class="sig sig-object c" id="c.LOG_MASK">
<span class="sig-name descname"><span class="n"><span class="pre">LOG_MASK</span></span></span><span class="sig-paren">(</span><span class="n"><span class="pre">p</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.LOG_MASK" title="Permalink to this definition"></a><br /></dt>
<dd><p>Returns the logmask corresponding priority <code class="docutils literal notranslate"><span class="pre">p</span></code></p>
</dd></dl>

<dl class="c macro">
<dt class="sig sig-object c" id="c.LOG_UPTO">
<span class="sig-name descname"><span class="n"><span class="pre">LOG_UPTO</span></span></span><span class="sig-paren">(</span><span class="n"><span class="pre">p</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.LOG_UPTO" title="Permalink to this definition"></a><br /></dt>
<dd><p>Returns the logmask of all SYSLOG priorities
up to and including <code class="docutils literal notranslate"><span class="pre">p</span></code>.</p>
</dd></dl>

<dl class="c macro">
<dt class="sig sig-object c" id="c.LOG_ALL">
<span class="sig-name descname"><span class="n"><span class="pre">LOG_ALL</span></span></span><a class="headerlink" href="#c.LOG_ALL" title="Permalink to this definition"></a><br /></dt>
<dd><p>Mask corresponding to all priorities enabled</p>
</dd></dl>

</section>
</section>


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