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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</span><hr><div class="refentry"><a name="sd_bus_request_name"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_bus_request_name, sd_bus_release_name — Request or release a well-known name on a bus</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-bus.h></pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_bus_request_name</b>(</code></td><td>sd_bus *<var class="pdparam">bus</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">name</var>, </td></tr><tr><td> </td><td>uint64_t <var class="pdparam">flags</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_bus_release_name</b>(</code></td><td>sd_bus *<var class="pdparam">bus</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">name</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm139697602185728"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_bus_request_name()</code> requests a
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well-known name on a bus. It takes a bus connection, a valid bus
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name and a flags parameter. The flags parameter is a combination
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of the following flags:</p><div class="variablelist"><dl class="variablelist"><dt id="SD_BUS_NAME_ALLOW_REPLACEMENT"><span class="term"><code class="varname">SD_BUS_NAME_ALLOW_REPLACEMENT</code></span><a class="headerlink" title="Permalink to this term" href="#SD_BUS_NAME_ALLOW_REPLACEMENT">¶</a></dt><dd><p>After acquiring the name successfully, permit
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other peers to take over the name when they try to acquire it
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with the <code class="varname">SD_BUS_NAME_REPLACE_EXISTING</code> flag
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set. If <code class="varname">SD_BUS_NAME_ALLOW_REPLACEMENT</code> is
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not set on the original request, such a request by other peers
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will be denied.</p></dd><dt id="SD_BUS_NAME_REPLACE_EXISTING"><span class="term"><code class="varname">SD_BUS_NAME_REPLACE_EXISTING</code></span><a class="headerlink" title="Permalink to this term" href="#SD_BUS_NAME_REPLACE_EXISTING">¶</a></dt><dd><p>Take over the name if it is already acquired
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by another peer, and that other peer has permitted takeover by
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setting <code class="varname">SD_BUS_NAME_ALLOW_REPLACEMENT</code> while
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acquiring it.</p></dd><dt id="SD_BUS_NAME_QUEUE"><span class="term"><code class="varname">SD_BUS_NAME_QUEUE</code></span><a class="headerlink" title="Permalink to this term" href="#SD_BUS_NAME_QUEUE">¶</a></dt><dd><p>Queue the acquisition of the name when the
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name is already taken.</p></dd></dl></div><p><code class="function">sd_bus_release_name()</code> releases an
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acquired well-known name. It takes a bus connection and a valid
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bus name as parameters.</p></div><div class="refsect1"><a name="idm139697602176208"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On success, these calls return 0 or a positive integer. On
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failure, these calls return a negative errno-style error
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code.</p><p>If <code class="varname">SD_BUS_NAME_QUEUE</code> is specified,
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<code class="function">sd_bus_request_name()</code> will return 0 when the
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name is already taken by another peer and the client has been
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added to the queue for the name. In that case, the caller can
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subscribe to "<code class="literal">NameOwnerChanged</code>" signals to be
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notified when the name is successfully acquired.
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<code class="function">sd_bus_request_name()</code> returns > 0 when the
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name has immediately been acquired successfully.</p></div><div class="refsect1"><a name="idm139697602171600"></a><h2 id="Errors">Errors<a class="headerlink" title="Permalink to this headline" href="#Errors">¶</a></h2><p>Returned errors may indicate the following problems:</p><div class="variablelist"><dl class="variablelist"><dt id="-EALREADY"><span class="term"><code class="constant">-EALREADY</code></span><a class="headerlink" title="Permalink to this term" href="#-EALREADY">¶</a></dt><dd><p>The caller already is the owner of the
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specified name.</p></dd><dt id="-EEXIST"><span class="term"><code class="constant">-EEXIST</code></span><a class="headerlink" title="Permalink to this term" href="#-EEXIST">¶</a></dt><dd><p>The name has already been acquired by a
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different peer, and SD_BUS_NAME_REPLACE_EXISTING was not
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specified or the other peer did not specify
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SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring the
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name.</p></dd><dt id="-ESRCH"><span class="term"><code class="constant">-ESRCH</code></span><a class="headerlink" title="Permalink to this term" href="#-ESRCH">¶</a></dt><dd><p>It was attempted to release a name that is
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currently not registered on the bus.</p></dd><dt id="-EADDRINUSE"><span class="term"><code class="constant">-EADDRINUSE</code></span><a class="headerlink" title="Permalink to this term" href="#-EADDRINUSE">¶</a></dt><dd><p>It was attempted to release a name that is
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owned by a different peer on the bus.</p></dd><dt id="-EINVAL"><span class="term"><code class="constant">-EINVAL</code></span><a class="headerlink" title="Permalink to this term" href="#-EINVAL">¶</a></dt><dd><p>A specified parameter is
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invalid.</p></dd><dt id="-ENOTCONN"><span class="term"><code class="constant">-ENOTCONN</code></span><a class="headerlink" title="Permalink to this term" href="#-ENOTCONN">¶</a></dt><dd><p>The bus connection has been
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disconnected.</p></dd><dt id="-ECHILD"><span class="term"><code class="constant">-ECHILD</code></span><a class="headerlink" title="Permalink to this term" href="#-ECHILD">¶</a></dt><dd><p>The bus connection has been created in a
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different process than the current one.</p></dd></dl></div></div><div class="refsect1"><a name="idm139697606062224"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_bus_acquire_name()</code> and
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<code class="function">sd_bus_release_name()</code> interfaces are
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available as a shared library, which can be compiled and linked to
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with the
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<code class="constant">libsystemd</code> <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
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file.</p></div><div class="refsect1"><a name="idm139697606057824"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
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<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
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<a href="sd-bus.html"><span class="citerefentry"><span class="refentrytitle">sd-bus</span>(3)</span></a>,
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<a href="sd_bus_new.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_new</span>(3)</span></a>
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</p></div></div></body></html>
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