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<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!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_path_encode">
<refentryinfo>
<title>sd_bus_path_encode</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_path_encode</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_path_encode</refname>
<refname>sd_bus_path_decode</refname>
<refpurpose>Convert an external identifier into an object path and back</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_path_encode</function></funcdef>
<paramdef>const char *<parameter>prefix</parameter></paramdef>
<paramdef>const char *<parameter>external_id</parameter></paramdef>
<paramdef>char **<parameter>ret_path</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_path_decode</function></funcdef>
<paramdef>const char *<parameter>path</parameter></paramdef>
<paramdef>const char *<parameter>prefix</parameter></paramdef>
<paramdef>char **<parameter>ret_external_id</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_path_encode()</function> and
<function>sd_bus_path_decode()</function> convert external
identifier strings into object paths and back. These functions are
useful to map application-specific string identifiers of any kind
into bus object paths in a simple, reversible and safe way.</para>
<para><function>sd_bus_path_encode()</function> takes a bus path
prefix and an external identifier string as arguments, plus a
place to store the returned bus path string. The bus path prefix
must be a valid bus path, starting with a slash
<literal>/</literal>, and not ending in one. The external
identifier string may be in any format, may be the empty string,
and has no restrictions on the charset — however, it must
always be <constant>NUL</constant>-terminated. The returned string
will be the concatenation of the bus path prefix plus an escaped
version of the external identifier string. This operation may be
reversed with <function>sd_bus_decode()</function>. It is
recommended to only use external identifiers that generally
require little escaping to be turned into valid bus path
identifiers (for example, by sticking to a 7-bit ASCII character
set), in order to ensure the resulting bus path is still short and
easily processed.</para>
<para><function>sd_bus_path_decode()</function> reverses the
operation of <function>sd_bus_path_encode()</function> and thus
regenerates an external identifier string from a bus path. It
takes a bus path and a prefix string, plus a place to store the
returned external identifier string. If the bus path does not
start with the specified prefix, 0 is returned and the returned
string is set to <constant>NULL</constant>. Otherwise, the
string following the prefix is unescaped and returned in the
external identifier string.</para>
<para>The escaping used will replace all characters which are
invalid in a bus object path by <literal>_</literal>, followed by a
hexadecimal value. As a special case, the empty string will be
replaced by a lone <literal>_</literal>.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, <function>sd_bus_path_encode()</function>
returns positive or 0, and a valid bus path in the return
argument. On success, <function>sd_bus_path_decode()</function>
returns a positive value if the prefixed matched, or 0 if it
did not. If the prefix matched, the external identifier is returned
in the return parameter. If it did not match, NULL is returned in
the return parameter. On failure, a negative errno-style error
number is returned by either function. The returned strings must
be
<citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>'d
by the caller.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para><function>sd_bus_path_encode()</function> and
<function>sd_bus_path_decode()</function> are available as a
shared library, which can be compiled and linked to with the
<constant>libsystemd</constant> <citerefentry project='die-net'><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 project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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