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| SPDX-License-Identifier: LGPL-2.1+ |
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| <refentry id="sd_bus_message_append_basic" xmlns:xi="http://www.w3.org/2001/XInclude"> |
| |
| <refentryinfo> |
| <title>sd_bus_message_append_basic</title> |
| <productname>systemd</productname> |
| </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 field 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>const void *<parameter>p</parameter></paramdef> |
| </funcprototype> |
| </funcsynopsis> |
| </refsynopsisdiv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para><function>sd_bus_message_append_basic()</function> appends a |
| single field to the message <parameter>m</parameter>. The |
| parameter <parameter>type</parameter> determines how the 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 type specifiers</title> |
| |
| <tgroup cols='5'> |
| <colspec colname='specifier' /> |
| <colspec colname='constant' /> |
| <colspec colname='description' /> |
| <colspec colname='size' /> |
| <colspec colname='ctype' /> |
| <thead> |
| <row> |
| <entry>Specifier</entry> |
| <entry>Constant</entry> |
| <entry>Description</entry> |
| <entry>Size</entry> |
| <entry>Expected C Type</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry><literal>y</literal></entry> |
| <entry><constant>SD_BUS_TYPE_BYTE</constant></entry> |
| <entry>unsigned integer</entry> |
| <entry>1 byte</entry> |
| <entry>uint8_t</entry> |
| </row> |
| |
| <row> |
| <entry><literal>b</literal></entry> |
| <entry><constant>SD_BUS_TYPE_BOOLEAN</constant></entry> |
| <entry>boolean</entry> |
| <entry>4 bytes</entry> |
| <entry>int</entry> |
| </row> |
| |
| <row> |
| <entry><literal>n</literal></entry> |
| <entry><constant>SD_BUS_TYPE_INT16</constant></entry> |
| <entry>signed integer</entry> |
| <entry>2 bytes</entry> |
| <entry>int16_t</entry> |
| </row> |
| |
| <row> |
| <entry><literal>q</literal></entry> |
| <entry><constant>SD_BUS_TYPE_UINT16</constant></entry> |
| <entry>unsigned integer</entry> |
| <entry>2 bytes</entry> |
| <entry>uint16_t</entry> |
| </row> |
| |
| <row> |
| <entry><literal>i</literal></entry> |
| <entry><constant>SD_BUS_TYPE_INT32</constant></entry> |
| <entry>signed integer</entry> |
| <entry>4 bytes</entry> |
| <entry>int32_t</entry> |
| </row> |
| |
| <row> |
| <entry><literal>u</literal></entry> |
| <entry><constant>SD_BUS_TYPE_UINT32</constant></entry> |
| <entry>unsigned integer</entry> |
| <entry>4 bytes</entry> |
| <entry>uint32_t</entry> |
| </row> |
| |
| <row> |
| <entry><literal>x</literal></entry> |
| <entry><constant>SD_BUS_TYPE_INT64</constant></entry> |
| <entry>signed integer</entry> |
| <entry>8 bytes</entry> |
| <entry>int64_t</entry> |
| </row> |
| |
| <row> |
| <entry><literal>t</literal></entry> |
| <entry><constant>SD_BUS_TYPE_UINT64</constant></entry> |
| <entry>unsigned integer</entry> |
| <entry>8 bytes</entry> |
| <entry>uint64_t</entry> |
| </row> |
| |
| <row> |
| <entry><literal>d</literal></entry> |
| <entry><constant>SD_BUS_TYPE_DOUBLE</constant></entry> |
| <entry>floating-point</entry> |
| <entry>8 bytes</entry> |
| <entry>double</entry> |
| </row> |
| |
| <row> |
| <entry><literal>s</literal></entry> |
| <entry><constant>SD_BUS_TYPE_STRING</constant></entry> |
| <entry>Unicode string</entry> |
| <entry>variable</entry> |
| <entry>char[]</entry> |
| </row> |
| |
| <row> |
| <entry><literal>o</literal></entry> |
| <entry><constant>SD_BUS_TYPE_OBJECT_PATH</constant></entry> |
| <entry>object path</entry> |
| <entry>variable</entry> |
| <entry>char[]</entry> |
| </row> |
| |
| <row> |
| <entry><literal>g</literal></entry> |
| <entry><constant>SD_BUS_TYPE_SIGNATURE</constant></entry> |
| <entry>signature</entry> |
| <entry>variable</entry> |
| <entry>char[]</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> |
| <entry>int</entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </table> |
| |
| <para>The value of the parameter is copied into a memory area held |
| by the message object, stays in the possession of the caller and |
| may hence be freely changed after this call without affecting the |
| bus message it has been added to. If <parameter>type</parameter> |
| is <literal>h</literal> (UNIX file descriptor), the descriptor is |
| duplicated by this call and the passed descriptor stays in |
| possession of the caller.</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 recipient 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><constant>-EINVAL</constant></term> |
| |
| <listitem><para>Specified parameter is invalid. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><constant>-EPERM</constant></term> |
| |
| <listitem><para>Message has been sealed. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><constant>-ESTALE</constant></term> |
| |
| <listitem><para>Message is in invalid state. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><constant>-ENXIO</constant></term> |
| |
| <listitem><para>Message cannot be appended to. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><constant>-ENOMEM</constant></term> |
| |
| <listitem><para>Memory allocation failed.</para></listitem> |
| </varlistentry> |
| </variablelist> |
| </refsect1> |
| |
| <xi:include href="libsystemd-pkgconfig.xml" /> |
| |
| <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> |