man/sd_bus_message_get_cookie.html

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  22   <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 214</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 &lt;systemd/sd-bus.h&gt;</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="idm214179228944"></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
  23                 the transaction cookie of a message. The cookie
  24                 uniquely identifies a message within each bus peer,
  25                 but is not globally unique. It is assigned when a
  26                 message is sent.</p><p><code class="function">sd_bus_message_get_reply_cookie()</code>
  27                 returns the transaction cookie of the message the
  28                 specified message is a response to. When a reply
  29                 message is generated for a method call message, its
  30                 cookie is copied over into this field. Note that while
  31                 every message that is transferred is identified by a
  32                 cookie, only response messages carry a reply cookie
  33                 field.</p><p>Both functions take a message object as first
  34                 parameter and a place to store the 64-bit cookie
  35                 in.</p></div><div class="refsect1"><a name="idm214179171968"></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
  36                 integer. On failure, these calls return a negative
  37                 errno-style error code.</p><p>On success, the cookie/reply cookie is returned
  38                 in the specified 64-bit unsigned integer variable.</p></div><div class="refsect1"><a name="idm214179777200"></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
  39                                 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
  40                                 assigned to this message. This either
  41                                 indicates that the message has not
  42                                 been sent yet and hence has no cookie
  43                                 assigned, or that the message is not a
  44                                 method response message and hence
  45                                 carries a reply cookie
  46                                 field.</p></dd></dl></div></div><div class="refsect1"><a name="idm214180026160"></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>
  47                 and <code class="function">sd_bus_message_get_reply_cookie()</code>
  48                 interfaces are available as a shared library, which can
  49                 be compiled and linked to with the
  50                 <code class="constant">libsystemd</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
  51                 file.</p></div><div class="refsect1"><a name="idm214180103824"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
  52                         <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
  53                         <a href="sd-bus.html"><span class="citerefentry"><span class="refentrytitle">sd-bus</span>(3)</span></a>,
  54                         <a href="sd_bus_new.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_new</span>(3)</span></a>
  55                 </p></div></div></body></html>