566f735e84e576e1592d0bf367182a0586944380Robert Wapshott<?xml version='1.0'?> <!--*-nxml-*-->

566f735e84e576e1592d0bf367182a0586944380Robert Wapshott<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

566f735e84e576e1592d0bf367182a0586944380Robert Wapshott"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

566f735e84e576e1592d0bf367182a0586944380Robert Wapshott

<refentry id="sd_bus_path_encode" conditional="ENABLE_KDBUS">

<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 &lt;systemd/sd-bus.h&gt;</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>prefix</parameter></paramdef>

<paramdef>const char *<parameter>path</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>, but not ending in one. The external

identifier string may be in any format, may be the empty string

and no restrictions on the charset are made - 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 here that generally

require little escaping to be turned into valid bus path

identifiers (for example by sticking to a 7bit 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 the

string following the prefix is unescaped and returned in the

external identifier string.</para>

<para>The escaping used will 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

didn't. 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><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><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>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>