man/sd_bus_message_append_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">
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   8 Copyright 2014 Zbigniew Jędrzejewski-Szmek
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  11 under the terms of the GNU Lesser General Public License as published by
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  23
  24 <refentry id="sd_bus_message_append_basic" conditional="ENABLE_KDBUS">
  25
  26   <refentryinfo>
  27     <title>sd_bus_message_append_basic</title>
  28     <productname>systemd</productname>
  29
  30     <authorgroup>
  31       <author>
  32         <contrib>A monkey with a typewriter</contrib>
  33         <firstname>Zbigniew</firstname>
  34         <surname>Jędrzejewski-Szmek</surname>
  35         <email>zbyszek@in.waw.pl</email>
  36       </author>
  37     </authorgroup>
  38   </refentryinfo>
  39
  40   <refmeta>
  41     <refentrytitle>sd_bus_message_append_basic</refentrytitle>
  42     <manvolnum>3</manvolnum>
  43   </refmeta>
  44
  45   <refnamediv>
  46     <refname>sd_bus_message_append_basic</refname>
  47
  48     <refpurpose>Attach a single part to a message</refpurpose>
  49   </refnamediv>
  50
  51   <refsynopsisdiv>
  52     <funcsynopsis>
  53       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  54
  55       <funcprototype>
  56         <funcdef>int sd_bus_message_append_basic</funcdef>
  57         <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
  58         <paramdef>char <parameter>type</parameter></paramdef>
  59         <paramdef>char void *<parameter>p</parameter></paramdef>
  60       </funcprototype>
  61     </funcsynopsis>
  62   </refsynopsisdiv>
  63
  64   <refsect1>
  65     <title>Description</title>
  66
  67     <para><function>sd_bus_message_append_basic</function> appends a
  68     single item to the message <parameter>m</parameter>. Parameter
  69     <parameter>type</parameter> determines how pointer
  70     <parameter>p</parameter> is interpreted.
  71     <parameter>type</parameter> must be one of the basic types
  72     as defined by the
  73
  74     <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic Types</ulink>
  75     section of the D-Bus specification, and listed in the table below.
  76     </para>
  77
  78     <table id='format-specifiers'>
  79       <title>Item format specifiers</title>
  80
  81       <tgroup cols='4'>
  82         <colspec colname='specifier' />
  83         <colspec colname='constant' />
  84         <colspec colname='description' />
  85         <colspec colname='size' />
  86         <thead>
  87           <row>
  88             <entry>Specifier</entry>
  89             <entry>Constant</entry>
  90             <entry>Description</entry>
  91             <entry>Size</entry>
  92           </row>
  93         </thead>
  94         <tbody>
  95           <row>
  96             <entry><literal>y</literal></entry>
  97             <entry><constant>SD_BUS_TYPE_BYTE</constant></entry>
  98             <entry>unsigned integer</entry>
  99             <entry>1 byte</entry>
 100           </row>
 101
 102           <row>
 103             <entry><literal>b</literal></entry>
 104             <entry><constant>SD_BUS_TYPE_BOOLEAN</constant></entry>
 105             <entry>boolean</entry>
 106             <entry>4 bytes</entry>
 107           </row>
 108
 109           <row>
 110             <entry><literal>n</literal></entry>
 111             <entry><constant>SD_BUS_TYPE_INT16</constant></entry>
 112             <entry>signed integer</entry>
 113             <entry>2 bytes</entry>
 114           </row>
 115
 116           <row>
 117             <entry><literal>q</literal></entry>
 118             <entry><constant>SD_BUS_TYPE_UINT16</constant></entry>
 119             <entry>unsigned integer</entry>
 120             <entry>2 bytes</entry>
 121           </row>
 122
 123           <row>
 124             <entry><literal>i</literal></entry>
 125             <entry><constant>SD_BUS_TYPE_INT32</constant></entry>
 126             <entry>signed integer</entry>
 127             <entry>4 bytes</entry>
 128           </row>
 129
 130           <row>
 131             <entry><literal>u</literal></entry>
 132             <entry><constant>SD_BUS_TYPE_UINT32</constant></entry>
 133             <entry>unsigned integer</entry>
 134             <entry>4 bytes</entry>
 135           </row>
 136
 137           <row>
 138             <entry><literal>x</literal></entry>
 139             <entry><constant>SD_BUS_TYPE_INT64</constant></entry>
 140             <entry>signed integer</entry>
 141             <entry>8 bytes</entry>
 142           </row>
 143
 144           <row>
 145             <entry><literal>t</literal></entry>
 146             <entry><constant>SD_BUS_TYPE_UINT64</constant></entry>
 147             <entry>unsigned integer</entry>
 148             <entry>8 bytes</entry>
 149           </row>
 150
 151           <row>
 152             <entry><literal>d</literal></entry>
 153             <entry><constant>SD_BUS_TYPE_DOUBLE</constant></entry>
 154             <entry>floating-point</entry>
 155             <entry>8 bytes</entry>
 156           </row>
 157
 158           <row>
 159             <entry><literal>s</literal></entry>
 160             <entry><constant>SD_BUS_TYPE_STRING</constant></entry>
 161             <entry>Unicode string</entry>
 162             <entry>variable</entry>
 163           </row>
 164
 165           <row>
 166             <entry><literal>o</literal></entry>
 167             <entry><constant>SD_BUS_TYPE_OBJECT_PATH</constant></entry>
 168             <entry>object path</entry>
 169             <entry>variable</entry>
 170           </row>
 171
 172           <row>
 173             <entry><literal>g</literal></entry>
 174             <entry><constant>SD_BUS_TYPE_SIGNATURE</constant></entry>
 175             <entry>signature</entry>
 176             <entry>variable</entry>
 177           </row>
 178
 179           <row>
 180             <entry><literal>h</literal></entry>
 181             <entry><constant>SD_BUS_TYPE_UNIX_FD</constant></entry>
 182             <entry>UNIX file descriptor</entry>
 183             <entry>4 bytes</entry>
 184           </row>
 185        </tbody>
 186       </tgroup>
 187     </table>
 188
 189     <para>The value of the parameter is copied into the memory area
 190     containing the message and may be changed after this call. If
 191     <parameter>type</parameter> is <literal>h</literal> (UNIX file
 192     descriptor), it is always "consumed" by this call, and either
 193     successfully appended to the message or closed.</para>
 194
 195     <para>For types <literal>s</literal>, <literal>o</literal>, and
 196     <literal>g</literal>, the parameter <parameter>p</parameter> is
 197     interpreted as a pointer to a <constant>NUL</constant>-terminated
 198     character sequence. As a special case, a <constant>NULL</constant>
 199     pointer is interpreted as an empty string. The string should be
 200     valid Unicode string encoded as UTF-8. In case of the two latter
 201     types, the additional requirements for a D-Bus object path or
 202     type signature should be satisfied. Those requirements should be
 203     verified by the recipient of the message.
 204     </para>
 205   </refsect1>
 206
 207   <refsect1>
 208     <title>Return Value</title>
 209
 210     <para>On success, this call returns 0 or a positive integer. On
 211     failure, it returns a negative errno-style error code.</para>
 212   </refsect1>
 213
 214   <refsect1 id='errors'>
 215     <title>Errors</title>
 216
 217     <para>Returned errors may indicate the following problems:</para>
 218
 219     <variablelist>
 220
 221       <varlistentry>
 222         <term><constant>-EINVAL</constant></term>
 223
 224         <listitem><para>Specified parameter is invalid.
 225         </para></listitem>
 226       </varlistentry>
 227
 228       <varlistentry>
 229         <term><constant>-EPERM</constant></term>
 230
 231         <listitem><para>Message has been sealed.
 232         </para></listitem>
 233       </varlistentry>
 234
 235       <varlistentry>
 236         <term><constant>-ESTALE</constant></term>
 237
 238         <listitem><para>Message is in invalid state.
 239         </para></listitem>
 240       </varlistentry>
 241
 242       <varlistentry>
 243         <term><constant>-ENXIO</constant></term>
 244
 245         <listitem><para>Message cannot be appended to.
 246         </para></listitem>
 247       </varlistentry>
 248
 249       <varlistentry>
 250         <term><constant>-ENOMEM</constant></term>
 251
 252         <listitem><para>Memory allocation failed.</para></listitem>
 253       </varlistentry>
 254     </variablelist>
 255   </refsect1>
 256
 257   <refsect1>
 258     <title>Notes</title>
 259
 260     <para>The <function>sd_bus_append_basic()</function> function
 261     described here is available as a shared library, which can be
 262     compiled and linked to with the
 263     <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 264     file.</para>
 265   </refsect1>
 266
 267   <refsect1>
 268     <title>See Also</title>
 269
 270     <para>
 271       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 272       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 273       <citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 274       <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink>
 275     </para>
 276   </refsect1>
 277
 278 </refentry>