man/sd_bus_message_read_basic.xml

   1 <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   This file is part of systemd.
   9
  10   Copyright 2016 Julian Orth
  11 -->
  12
  13 <refentry id="sd_bus_message_read_basic">
  14
  15   <refentryinfo>
  16     <title>sd_bus_message_read_basic</title>
  17     <productname>systemd</productname>
  18
  19     <authorgroup>
  20       <author>
  21         <firstname>Julian</firstname>
  22         <surname>Orth</surname>
  23         <email>ju.orth@gmail.com</email>
  24       </author>
  25     </authorgroup>
  26   </refentryinfo>
  27
  28   <refmeta>
  29     <refentrytitle>sd_bus_message_read_basic</refentrytitle>
  30     <manvolnum>3</manvolnum>
  31   </refmeta>
  32
  33   <refnamediv>
  34     <refname>sd_bus_message_read_basic</refname>
  35
  36     <refpurpose>Read a basic type from a message</refpurpose>
  37   </refnamediv>
  38
  39   <refsynopsisdiv>
  40     <funcsynopsis>
  41       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  42
  43       <funcprototype>
  44         <funcdef>int <function>sd_bus_message_read_basic</function></funcdef>
  45         <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
  46         <paramdef>char <parameter>type</parameter></paramdef>
  47         <paramdef>void *<parameter>p</parameter></paramdef>
  48       </funcprototype>
  49     </funcsynopsis>
  50   </refsynopsisdiv>
  51
  52   <refsect1>
  53     <title>Description</title>
  54
  55     <para>
  56       <function>sd_bus_message_read_basic()</function> reads a basic type from a
  57       message and advances the read position in the message. The set of basic
  58       types and their ascii codes passed in <parameter>type</parameter> are
  59       described in the <ulink
  60         url="https://dbus.freedesktop.org/doc/dbus-specification.html">D-Bus
  61         Specification</ulink>.
  62     </para>
  63
  64     <para>
  65       If <parameter>p</parameter> is not NULL, it should contain a pointer to an
  66       appropriate object. For example, if <parameter>type</parameter> is
  67       <constant>'y'</constant>, the object passed in <parameter>p</parameter>
  68       should have type <code>uint8_t *</code>. If <parameter>type</parameter>
  69       is <constant>'s'</constant>, the object passed in <parameter>p</parameter>
  70       should have type <code>const char **</code>. Note that, if the basic type
  71       is a pointer (e.g., <code>const char *</code> in the case of a string),
  72       the pointer is only borrowed and the contents must be copied if they are
  73       to be used after the end of the messages lifetime. Similarly, during the
  74       lifetime of such a pointer, the message must not be modified.
  75     </para>
  76
  77     <para>
  78       If there is no object of the specified type at the current position in the
  79       message, an error is returned.
  80     </para>
  81   </refsect1>
  82
  83   <refsect1>
  84     <title>Return Value</title>
  85
  86     <para>
  87       On success, <function>sd_bus_message_read_basic()</function> returns 0 or
  88       a positive integer. On failure, it returns a negative errno-style error
  89       code.
  90     </para>
  91   </refsect1>
  92
  93   <refsect1>
  94     <title>See Also</title>
  95
  96     <para>
  97       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  98       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  99     </para>
 100   </refsect1>
 101
 102 </refentry>