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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_bus_message_get_cookie</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 215</span><hr><div class="refentry"><a name="sd_bus_message_get_cookie"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_bus_message_get_cookie, sd_bus_message_get_reply_cookie — Returns the transaction cookie of a message</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_message_get_cookie</b>(</code></td><td>sd_bus_message *<var class="pdparam">message</var>, </td></tr><tr><td> </td><td>uint64_t *<var class="pdparam">cookie</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_message_get_reply_cookie</b>(</code></td><td>sd_bus_message *<var class="pdparam">message</var>, </td></tr><tr><td> </td><td>uint64_t *<var class="pdparam">cookie</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm214165938928"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_bus_message_get_cookie()</code> returns
the transaction cookie of a message. The cookie
uniquely identifies a message within each bus peer,
but is not globally unique. It is assigned when a
message is sent.</p><p><code class="function">sd_bus_message_get_reply_cookie()</code>
returns the transaction cookie of the message the
specified message is a response to. When a reply
message is generated for a method call message, its
cookie is copied over into this field. Note that while
every message that is transferred is identified by a
cookie, only response messages carry a reply cookie
field.</p><p>Both functions take a message object as first
parameter and a place to store the 64-bit cookie
in.</p></div><div class="refsect1"><a name="idm214168449712"></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 failure, these calls return a negative
errno-style error code.</p><p>On success, the cookie/reply cookie is returned
in the specified 64-bit unsigned integer variable.</p></div><div class="refsect1"><a name="idm214167487344"></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="-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
is invalid.</p></dd><dt id="-ENODATA"><span class="term"><code class="varname">-ENODATA</code></span><a class="headerlink" title="Permalink to this term" href="#-ENODATA">¶</a></dt><dd><p>No cookie has been
assigned to this message. This either
indicates that the message has not
been sent yet and hence has no cookie
assigned, or that the message is not a
method response message and hence
carries a reply cookie
field.</p></dd></dl></div></div><div class="refsect1"><a name="idm214166489008"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_bus_message_get_cookie()</code>
and <code class="function">sd_bus_message_get_reply_cookie()</code>
interfaces are available as a shared library, which can
be compiled and linked to with the
<code class="constant">libsystemd</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
file.</p></div><div class="refsect1"><a name="idm214166665392"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="sd-bus.html"><span class="citerefentry"><span class="refentrytitle">sd-bus</span>(3)</span></a>,
<a href="sd_bus_new.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_new</span>(3)</span></a>
</p></div></div></body></html>
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