mirror of
https://github.com/systemd/systemd.git
synced 2024-12-27 07:22:31 +03:00
8d29a1b9c5
Prompted-by: https://lists.freedesktop.org/archives/systemd-devel/2020-September/045264.html
179 lines
7.7 KiB
XML
179 lines
7.7 KiB
XML
<?xml version='1.0'?>
|
|
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
|
<!-- SPDX-License-Identifier: LGPL-2.1+ -->
|
|
|
|
<refentry id="sd_bus_message_open_container"
|
|
xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_bus_message_open_container</title>
|
|
<productname>systemd</productname>
|
|
</refentryinfo>
|
|
|
|
<refmeta>
|
|
<refentrytitle>sd_bus_message_open_container</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_bus_message_open_container</refname>
|
|
<refname>sd_bus_message_close_container</refname>
|
|
<refname>sd_bus_message_enter_container</refname>
|
|
<refname>sd_bus_message_exit_container</refname>
|
|
|
|
<refpurpose>Create and move between containers in D-Bus messages</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
|
|
|
|
<funcprototype>
|
|
<funcdef>int sd_bus_message_open_container</funcdef>
|
|
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
|
|
<paramdef>char <parameter>type</parameter></paramdef>
|
|
<paramdef>const char *<parameter>contents</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int sd_bus_message_close_container</funcdef>
|
|
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int sd_bus_message_enter_container</funcdef>
|
|
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
|
|
<paramdef>char <parameter>type</parameter></paramdef>
|
|
<paramdef>const char *<parameter>contents</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int sd_bus_message_exit_container</funcdef>
|
|
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para><function>sd_bus_message_open_container()</function> appends a new container to the message
|
|
<parameter>m</parameter>. After opening a new container, it can be filled with content using
|
|
<citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
and similar functions. Containers behave like a stack. To nest containers inside each other, call
|
|
<function>sd_bus_message_open_container()</function> multiple times without calling
|
|
<function>sd_bus_message_close_container()</function> in between. Each container will be nested inside the
|
|
previous container. <parameter>type</parameter> represents the container type and should be one of
|
|
<literal>r</literal>, <literal>a</literal>, <literal>v</literal> or <literal>e</literal> as described in
|
|
<citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
|
Instead of literals, the corresponding constants <constant>SD_BUS_TYPE_STRUCT</constant>,
|
|
<constant>SD_BUS_TYPE_ARRAY</constant>, <constant>SD_BUS_TYPE_VARIANT</constant> or
|
|
<constant>SD_BUS_TYPE_DICT_ENTRY</constant> can also be used. <parameter>contents</parameter> describes
|
|
the type of the container's elements and should be a D-Bus type string following the rules described in
|
|
<citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
|
</para>
|
|
|
|
<para><function>sd_bus_message_close_container()</function> closes the last container opened with
|
|
<function>sd_bus_message_open_container()</function>. On success, the write pointer of the message
|
|
<parameter>m</parameter> is positioned after the closed container in its parent container or in
|
|
<parameter>m</parameter> itself if there is no parent container.</para>
|
|
|
|
<para><function>sd_bus_message_enter_container()</function> enters the next container of the message
|
|
<parameter>m</parameter> for reading. It behaves mostly the same as
|
|
<function>sd_bus_message_open_container()</function>. Entering a container allows reading its contents
|
|
with
|
|
<citerefentry><refentrytitle>sd_bus_message_read</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
and similar functions. <parameter>type</parameter> and <parameter>contents</parameter> are the same as in
|
|
<function>sd_bus_message_open_container()</function>.</para>
|
|
|
|
<para><function>sd_bus_message_exit_container()</function> exits the scope of the last container entered
|
|
with <function>sd_bus_message_enter_container()</function>. It behaves mostly the same as
|
|
<function>sd_bus_message_close_container()</function>. Note that
|
|
<function>sd_bus_message_exit_container()</function> may only be called after iterating through all
|
|
members of the container, i.e. reading or skipping them. Use
|
|
<citerefentry><refentrytitle>sd_bus_message_skip</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
to skip over felds of a container in order to be able to exit the container with
|
|
<function>sd_bus_message_exit_container()</function> without reading all members.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Return Value</title>
|
|
|
|
<para>On success, these functions return a non-negative integer. On failure, they return a negative
|
|
errno-style error code.</para>
|
|
|
|
<refsect2>
|
|
<title>Errors</title>
|
|
|
|
<para>Returned errors may indicate the following problems:</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>-EINVAL</constant></term>
|
|
|
|
<listitem><para><parameter>m</parameter> or <parameter>contents</parameter> are
|
|
<constant>NULL</constant> or <parameter>type</parameter> is invalid.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-EPERM</constant></term>
|
|
|
|
<listitem><para>The message <parameter>m</parameter> is already sealed.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-ESTALE</constant></term>
|
|
|
|
<listitem><para>The message <parameter>m</parameter> is in an invalid state.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-ENOMEM</constant></term>
|
|
|
|
<listitem><para>Memory allocation failed.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-EBUSY</constant></term>
|
|
|
|
<listitem><para><function>sd_bus_message_exit_container()</function> was called but there are
|
|
unread members left in the container.</para></listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect2>
|
|
</refsect1>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" />
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<example>
|
|
<title>Append an array of strings to a message</title>
|
|
|
|
<programlisting><xi:include href="sd-bus-container-append.c" parse="text" /></programlisting>
|
|
</example>
|
|
|
|
<example>
|
|
<title>Read an array of strings from a message</title>
|
|
|
|
<programlisting><xi:include href="sd-bus-container-read.c" parse="text" /></programlisting>
|
|
</example>
|
|
</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>,
|
|
<citerefentry><refentrytitle>sd_bus_message_read</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd_bus_message_skip</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<ulink url="https://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink>
|
|
</para>
|
|
</refsect1>
|
|
|
|
</refentry>
|