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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/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_bus_message_read_strv" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_message_read_strv</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_message_read_strv</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_message_read_strv</refname>
<refname>sd_bus_message_read_strv_extend</refname>
<refpurpose>Access an array of strings in a message</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_message_read_strv</function></funcdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>char ***<parameter>l</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_message_read_strv_extend</function></funcdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>char ***<parameter>l</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_message_read_strv()</function> reads an array of string-like items from the
message <parameter>m</parameter>. The "read pointer" in the message must be right before an array of
strings (D-Bus type <literal>as</literal>), object paths (D-Bus type <literal>ao</literal>), or
signatures (D-Bus type <literal>ag</literal>). On success, a pointer to a
<constant>NULL</constant>-terminated array of strings (strv) is returned in the output parameter
<parameter>l</parameter>. Note that ownership of this array is transferred to the caller. Hence, the
caller is responsible for freeing this array and its contents. Also note that as a matter of
optimization, if an empty array is encountered a <constant>NULL</constant> pointer might be returned
here, and should be considered equivalent to an array with zero entries.</para>
<para><function>sd_bus_message_read_strv_extend()</function> is similar, but the second parameter is an
input-output parameter. If <parameter>*l</parameter> is <constant>NULL</constant>, if behaves identically
to <function>sd_bus_message_read_strv()</function>. Otherwise, <parameter>*l</parameter> must point to a
strv, which will be reallocated and extended with additional strings. This function is particularly
useful when combining multiple lists of strings in a message or messages into a single array of strings.
</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>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para><parameter>m</parameter> or <parameter>l</parameter> are <constant>NULL</constant>.
</para>
<xi:include href="version-info.xml" xpointer="v246"/></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EPERM</constant></term>
<listitem><para>The message is not sealed.</para>
<xi:include href="version-info.xml" xpointer="v246"/></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EBADMSG</constant></term>
<listitem><para>The message cannot be parsed.</para>
<xi:include href="version-info.xml" xpointer="v246"/></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENXIO</constant></term>
<listitem><para>The message "read pointer" is not right before an array of the appropriate type.
</para>
<xi:include href="version-info.xml" xpointer="v248"/></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<refsect1>
<title>History</title>
<para><function>sd_bus_message_read_strv()</function> was added in version 246.</para>
<para><function>sd_bus_message_read_strv_extend()</function> was added in version 252.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd_bus_message_read</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>
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