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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="sd_bus_send"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_send</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_send</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_send</refname>
<refname>sd_bus_send_to</refname>
<refpurpose>Queue a D-Bus message for transfer</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_send</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>uint64_t *<parameter>cookie</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_send_to</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>const char *<parameter>destination</parameter></paramdef>
<paramdef>uint64_t *<parameter>cookie</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_send()</function> queues the bus message object <parameter>m</parameter> for
transfer. If <parameter>bus</parameter> is <constant>NULL</constant>, the bus that
<parameter>m</parameter> is attached to is used. <parameter>bus</parameter> only needs to be set when the
message is sent to a different bus than the one it's attached to, for example when forwarding messages.
If the output parameter <parameter>cookie</parameter> is not <constant>NULL</constant>, it is set to the
message identifier. This value can later be used to match incoming replies to their corresponding
messages. If <parameter>cookie</parameter> is set to <constant>NULL</constant> and the message is not
sealed, <function>sd_bus_send()</function> assumes the message <parameter>m</parameter> doesn't expect a
reply and adds the necessary headers to indicate this.</para>
<para>Note that in most scenarios, <function>sd_bus_send()</function> should not be called
directly. Instead, use higher level functions such as
<citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
<citerefentry><refentrytitle>sd_bus_reply_method_return</refentrytitle><manvolnum>3</manvolnum></citerefentry>
which call <function>sd_bus_send()</function> internally.</para>
<para><function>sd_bus_send_to()</function> is a shorthand for sending a message to a specific
destination. It's main use case is to simplify sending unicast signal messages (signals that only have a
single receiver). It's behavior is similar to calling
<citerefentry><refentrytitle>sd_bus_message_set_destination</refentrytitle><manvolnum>3</manvolnum></citerefentry>
followed by calling <function>sd_bus_send()</function>.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, these functions return a non-negative integer. On failure, they return a negative
errno-style error code.</para>
<refsect2 id='errors'>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>The input parameter <parameter>m</parameter> is <constant>NULL</constant>.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EOPNOTSUPP</constant></term>
<listitem><para>The bus connection does not support sending file descriptors.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ECHILD</constant></term>
<listitem><para>The bus connection was allocated in a parent process and is being reused in a child
process after <function>fork()</function>.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOBUFS</constant></term>
<listitem><para>The bus connection's write queue is full.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOTCONN</constant></term>
<listitem><para>The input parameter <parameter>bus</parameter> is
<constant>NULL</constant> or the bus is not connected.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ECONNRESET</constant></term>
<listitem><para>The bus connection was closed while waiting for the response.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_call_method</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_message_set_destination</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_reply_method_return</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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