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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 214</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="idm214183571808"></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
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a well-known name on a bus. It takes a bus connection,
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a valid bus name and a flags parameter. The flags
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parameter is a combination of the following
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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
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name successfully, permit other peers
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to take over the name when they try to
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acquire it with the
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<code class="varname">SD_BUS_NAME_REPLACE_EXISTING</code>
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flag set. If
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<code class="varname">SD_BUS_NAME_ALLOW_REPLACEMENT</code>
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is not set on the original request,
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such a request by other peers will be
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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
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if it is already acquired by another
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peer, and that other peer has permitted
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takeover by setting
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<code class="varname">SD_BUS_NAME_ALLOW_REPLACEMENT</code>
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while 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
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of the name when the name is already
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taken.</p></dd></dl></div><p><code class="function">sd_bus_release_name()</code> releases
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an acquired well-known name. It takes a bus connection
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and a valid bus name as parameters.</p></div><div class="refsect1"><a name="idm214183800816"></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
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integer. On failure, these calls return a negative
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errno-style error code.</p><p>If <code class="varname">SD_BUS_NAME_QUEUE</code> is
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specified, <code class="function">sd_bus_request_name()</code>
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will return 0 when the name is already taken by
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another peer and the client has been added to the
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queue for the name. In that case, the caller can
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subscribe to "<code class="literal">NameOwnerChanged</code>"
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signals to be notified when the name is successfully
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acquired. <code class="function">sd_bus_request_name()</code>
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returns > 0 when the name has immediately been
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acquired successfully.</p></div><div class="refsect1"><a name="idm214183114928"></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="varname">-EALREADY</code></span><a class="headerlink" title="Permalink to this term" href="#-EALREADY">¶</a></dt><dd><p>The caller already is
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the owner of the specified
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name.</p></dd><dt id="-EEXIST"><span class="term"><code class="varname">-EEXIST</code></span><a class="headerlink" title="Permalink to this term" href="#-EEXIST">¶</a></dt><dd><p>The name has already
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been acquired by a different peer, and
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SD_BUS_NAME_REPLACE_EXISTING was not
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specified or the other peer did not
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specify SD_BUS_NAME_ALLOW_REPLACEMENT
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while acquiring the
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name.</p></dd><dt id="-ESRCH"><span class="term"><code class="varname">-ESRCH</code></span><a class="headerlink" title="Permalink to this term" href="#-ESRCH">¶</a></dt><dd><p>It was attempted to
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release a name that is currently not
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registered on the
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bus.</p></dd><dt id="-EADDRINUSE"><span class="term"><code class="varname">-EADDRINUSE</code></span><a class="headerlink" title="Permalink to this term" href="#-EADDRINUSE">¶</a></dt><dd><p>It was attempted to
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release a name that is owned by a
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different peer on the
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bus.</p></dd><dt id="-EINVAL"><span class="term"><code class="varname">-EINVAL</code></span><a class="headerlink" title="Permalink to this term" href="#-EINVAL">¶</a></dt><dd><p>A specified parameter
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is invalid.</p></dd><dt id="-ENOTCONN"><span class="term"><code class="varname">-ENOTCONN</code></span><a class="headerlink" title="Permalink to this term" href="#-ENOTCONN">¶</a></dt><dd><p>The bus connection has
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been disconnected.</p></dd><dt id="-ECHILD"><span class="term"><code class="varname">-ECHILD</code></span><a class="headerlink" title="Permalink to this term" href="#-ECHILD">¶</a></dt><dd><p>The bus connection has
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been created in a different process
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than the current one.</p></dd></dl></div></div><div class="refsect1"><a name="idm214182875920"></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>
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and <code class="function">sd_bus_release_name()</code>
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interfaces are available as a shared library, which can
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be compiled and linked to with the
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<code class="constant">libsystemd</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
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file.</p></div><div class="refsect1"><a name="idm214185727168"></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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