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<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!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+
This file is part of systemd.
Copyright 2016 Julian Orth
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sd_bus_message_read_basic">
<refentryinfo>
<title>sd_bus_message_read_basic</title>
<productname>systemd</productname>
<authorgroup>
<author>
<firstname>Julian</firstname>
<surname>Orth</surname>
<email>ju.orth@gmail.com</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_message_read_basic</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_message_read_basic</refname>
<refpurpose>Read a basic type from a message</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_message_read_basic</function></funcdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>char <parameter>type</parameter></paramdef>
<paramdef>void *<parameter>p</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<function>sd_bus_message_read_basic()</function> reads a basic type from a
message and advances the read position in the message. The set of basic
types and their ascii codes passed in <parameter>type</parameter> are
described in the <ulink
url="https://dbus.freedesktop.org/doc/dbus-specification.html">D-Bus
Specification</ulink>.
</para>
<para>
If <parameter>p</parameter> is not NULL, it should contain a pointer to an
appropriate object. For example, if <parameter>type</parameter> is
<constant>'y'</constant>, the object passed in <parameter>p</parameter>
should have type <code>uint8_t *</code>. If <parameter>type</parameter>
is <constant>'s'</constant>, the object passed in <parameter>p</parameter>
should have type <code>const char **</code>. Note that, if the basic type
is a pointer (e.g., <code>const char *</code> in the case of a string),
the pointer is only borrowed and the contents must be copied if they are
to be used after the end of the messages lifetime. Similarly, during the
lifetime of such a pointer, the message must not be modified.
</para>
<para>
If there is no object of the specified type at the current position in the
message, an error is returned.
</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>
On success, <function>sd_bus_message_read_basic()</function> returns 0 or
a positive integer. On failure, it returns a negative errno-style error
code.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
</para>
</refsect1>
</refentry>
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