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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="sd_bus_message_read_array">
<refentryinfo>
<title>sd_bus_message_read_array</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_message_read_array</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_message_read_array</refname>
<refpurpose>Access an array of elements in a message</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_message_read_array</function></funcdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>char <parameter>type</parameter></paramdef>
<paramdef>const void **<parameter>ptr</parameter></paramdef>
<paramdef>size_t *<parameter>size</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_message_read_array()</function> gives access to an element array in
message <parameter>m</parameter>. The "read pointer" in the message must be right before an
array of type <parameter>type</parameter>. As a special case, <parameter>type</parameter> may be
<constant>NUL</constant>, in which case any type is acceptable. A pointer to the array data is
returned in the parameter <parameter>ptr</parameter> and the size of array data (in bytes) is
returned in the parameter <parameter>size</parameter>. If <parameter>size</parameter> is 0, a
valid non-null pointer will be returned, but it may not be dereferenced. The data is aligned as
appropriate for the data type. The data is part of the message — it may not be modified and is
valid only as long as the message is referenced. After this function returns, the "read pointer"
points at the next element after the array.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>
On success, <function>sd_bus_message_read_array()</function> returns 0 or
a positive integer. On failure, it returns a negative errno-style error
code.
</para>
</refsect1>
<refsect1 id='errors'>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>Specified type is invalid or the message parameter or one of the output
parameters are <constant>NULL</constant>.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EOPNOTSUPP</constant></term>
<listitem><para>The byte order in the message is different than native byte
order.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EPERM</constant></term>
<listitem><para>The message is not sealed.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EBADMSG</constant></term>
<listitem><para>The message cannot be parsed.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<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_message_read</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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