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<H1>SD_BUS_MESSAGE_GET_COOKIE</H1>
Section: sd_bus_message_get_cookie (3)<BR>Updated: <BR><A HREF="#index">Index</A>
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<H2>NAME</H2>
sd_bus_message_get_cookie, sd_bus_message_get_reply_cookie - Returns the transaction cookie of a message
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<H2>SYNOPSIS</H2>
<P>
<B>
</B><PRE>
#include &lt;<A HREF="file:///usr/include/systemd/sd-bus.h">systemd/sd-bus.h</A>&gt;
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<DT id="1">
<B>int sd_bus_message_get_cookie(sd_bus_message&nbsp;*</B><I>message</I><B>, uint64_t&nbsp;*</B><I>cookie</I><B>);</B>
<DT id="2">
<B>int sd_bus_message_get_reply_cookie(sd_bus_message&nbsp;*</B><I>message</I><B>, uint64_t&nbsp;*</B><I>cookie</I><B>);</B>
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<H2>DESCRIPTION</H2>
<P>
<B>sd_bus_message_get_cookie()</B>
<DD>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.
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<B>sd_bus_message_get_reply_cookie()</B>
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>
Both functions take a message object as first parameter and a place to store the 64-bit cookie in.
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<H2>RETURN VALUE</H2>
<P>
On success, these calls return 0 or a positive integer. On failure, they return a negative errno-style error code.
<P>
On success, the cookie/reply cookie is returned in the specified 64-bit unsigned integer variable.
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<H3>Errors</H3>
<P>
Returned errors may indicate the following problems:
<P>
<B>-EINVAL</B>
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A specified parameter is invalid.
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<B>-ENODATA</B>
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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.
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<H2>NOTES</H2>
<P>
These APIs are implemented as a shared library, which can be compiled and linked to with the
<B>libsystemd</B>&nbsp;<B><A HREF="/cgi-bin/man/man2html?1+pkg-config">pkg-config</A></B>(1)
file.
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<H2>SEE ALSO</H2>
<P>
<B><A HREF="/cgi-bin/man/man2html?1+systemd">systemd</A></B>(1),
<B><A HREF="/cgi-bin/man/man2html?3+sd-bus">sd-bus</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_new">sd_bus_new</A></B>(3)
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<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="5"><A HREF="#lbAB">NAME</A><DD>
<DT id="6"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="7"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="8"><A HREF="#lbAE">RETURN VALUE</A><DD>
<DL>
<DT id="9"><A HREF="#lbAF">Errors</A><DD>
</DL>
<DT id="10"><A HREF="#lbAG">NOTES</A><DD>
<DT id="11"><A HREF="#lbAH">SEE ALSO</A><DD>
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