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systemd/man/sd_bus_path_encode.xml
Tom Gundersen 12b42c7667 man: revert dynamic paths for split-usr setups
This did not really work out as we had hoped. Trying to do this upstream
introduced several problems that probably makes it better suited as a
downstream patch after all. At any rate, it is not releaseable in the
current state, so we at least need to revert this before the release.

 * by adjusting the path to binaries, but not do the same thing to the
   search path we end up with inconsistent man-pages. Adjusting the search
   path too would be quite messy, and it is not at all obvious that this is
   worth the effort, but at any rate it would have to be done before we
   could ship this.

 * this means that distributed man-pages does not make sense as they depend
   on config options, and for better or worse we are still distributing
   man pages, so that is something that definitely needs sorting out before
   we could ship with this patch.

 * we have long held that split-usr is only minimally supported in order
   to boot, and something we hope will eventually go away. So before we start
   adding even more magic/effort in order to make this work nicely, we should
   probably question if it makes sense at all.
2015-06-18 19:47:44 +02:00

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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 &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>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>