<?xml version='1.0'?> <!--*-nxml-*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. Copyright 2014 Zbigniew Jędrzejewski-Szmek 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_append_basic" conditional="ENABLE_KDBUS"> <refentryinfo> <title>sd_bus_message_append_basic</title> <productname>systemd</productname> <authorgroup> <author> <contrib>A monkey with a typewriter</contrib> <firstname>Zbigniew</firstname> <surname>Jędrzejewski-Szmek</surname> <email>zbyszek@in.waw.pl</email> </author> </authorgroup> </refentryinfo> <refmeta> <refentrytitle>sd_bus_message_append_basic</refentrytitle> <manvolnum>3</manvolnum> </refmeta> <refnamediv> <refname>sd_bus_message_append_basic</refname> <refpurpose>Attach a single part to a message</refpurpose> </refnamediv> <refsynopsisdiv> <funcsynopsis> <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> <funcprototype> <funcdef>int sd_bus_message_append_basic</funcdef> <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> <paramdef>char <parameter>type</parameter></paramdef> <paramdef>char void *<parameter>p</parameter></paramdef> </funcprototype> </funcsynopsis> </refsynopsisdiv> <refsect1> <title>Description</title> <para><function>sd_bus_message_append_basic</function> appends a single item to the message <parameter>m</parameter>. Parameter <parameter>type</parameter> determines how pointer <parameter>p</parameter> is interpreted. <parameter>type</parameter> must be one of the basic types as defined by the <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic Types</ulink> section of the D-Bus specification, and listed in the table below. </para> <table id='format-specifiers'> <title>Item format specifiers</title> <tgroup cols='4'> <colspec colname='specifier' /> <colspec colname='constant' /> <colspec colname='description' /> <colspec colname='size' /> <thead> <row> <entry>Specifier</entry> <entry>Constant</entry> <entry>Description</entry> <entry>Size</entry> </row> </thead> <tbody> <row> <entry><literal>y</literal></entry> <entry><constant>SD_BUS_TYPE_BYTE</constant></entry> <entry>unsigned interger</entry> <entry>1 byte</entry> </row> <row> <entry><literal>b</literal></entry> <entry><constant>SD_BUS_TYPE_BOOLEAN</constant></entry> <entry>boolean</entry> <entry>4 bytes</entry> </row> <row> <entry><literal>n</literal></entry> <entry><constant>SD_BUS_TYPE_INT16</constant></entry> <entry>signed integer</entry> <entry>2 bytes</entry> </row> <row> <entry><literal>q</literal></entry> <entry><constant>SD_BUS_TYPE_UINT16</constant></entry> <entry>unsigned integer</entry> <entry>2 bytes</entry> </row> <row> <entry><literal>i</literal></entry> <entry><constant>SD_BUS_TYPE_INT32</constant></entry> <entry>signed integer</entry> <entry>4 bytes</entry> </row> <row> <entry><literal>u</literal></entry> <entry><constant>SD_BUS_TYPE_UINT32</constant></entry> <entry>unsigned integer</entry> <entry>4 bytes</entry> </row> <row> <entry><literal>x</literal></entry> <entry><constant>SD_BUS_TYPE_INT64</constant></entry> <entry>signed integer</entry> <entry>8 bytes</entry> </row> <row> <entry><literal>t</literal></entry> <entry><constant>SD_BUS_TYPE_UINT64</constant></entry> <entry>unsigned integer</entry> <entry>8 bytes</entry> </row> <row> <entry><literal>d</literal></entry> <entry><constant>SD_BUS_TYPE_DOUBLE</constant></entry> <entry>floating-point</entry> <entry>8 bytes</entry> </row> <row> <entry><literal>s</literal></entry> <entry><constant>SD_BUS_TYPE_STRING</constant></entry> <entry>Unicode string</entry> <entry>variable</entry> </row> <row> <entry><literal>o</literal></entry> <entry><constant>SD_BUS_TYPE_OBJECT_PATH</constant></entry> <entry>object path</entry> <entry>variable</entry> </row> <row> <entry><literal>g</literal></entry> <entry><constant>SD_BUS_TYPE_SIGNATURE</constant></entry> <entry>signature</entry> <entry>variable</entry> </row> <row> <entry><literal>h</literal></entry> <entry><constant>SD_BUS_TYPE_UNIX_FD</constant></entry> <entry>UNIX file descriptor</entry> <entry>4 bytes</entry> </row> </tbody> </tgroup> </table> <para>The value of the parameter is copied into the memory area containing the message and may be changed after this call. If <parameter>type</parameter> is <literal>h</literal> (UNIX file descriptor), it is always "consumed" by this call, and either successfully appended to the message or closed.</para> <para>For types <literal>s</literal>, <literal>o</literal>, and <literal>g</literal>, the parameter <parameter>p</parameter> is interpreted as a pointer to a <constant>NUL</constant>-terminated character sequence. As a special case, a <constant>NULL</constant> pointer is interpreted as an empty string. The string should be valid Unicode string encoded as UTF-8. In case of the two latter types, the additional requirements for a D-Bus object path or type signature should be satisfied. Those requirements should be verified by the recepient of the message. </para> </refsect1> <refsect1> <title>Return Value</title> <para>On success, this call 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><varname>-EINVAL</varname></term> <listitem><para>Specified parameter is invalid. </para></listitem> </varlistentry> <varlistentry> <term><varname>-EPERM</varname></term> <listitem><para>Message has been sealed. </para></listitem> </varlistentry> <varlistentry> <term><varname>-ESTALE</varname></term> <listitem><para>Message is in invalid state. </para></listitem> </varlistentry> <varlistentry> <term><varname>-ENXIO</varname></term> <listitem><para>Message cannot be appended to. </para></listitem> </varlistentry> <varlistentry> <term><varname>-ENOMEM</varname></term> <listitem><para>Memory allocation failed.</para></listitem> </varlistentry> </variablelist> </refsect1> <refsect1> <title>Notes</title> <para>The <function>sd_bus_append_basic()</function> function described here is available as a shared library, which can be compiled and linked to with the <constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</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>, <citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink> </para> </refsect1> </refentry>