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1eecafb8c1
As requested in https://github.com/systemd/systemd/pull/4864#pullrequestreview-12372557. docbook will substitute triple dots for the ellipsis in man output, so this has no effect on the troff output, only on HTML, making it infinitesimally nicer. In some places we show output from programs, which use dots, and those places should not be changed. In some tables, the alignment would change if dots were changed to the ellipsis which is only one character. Since docbook replaces the ellipsis automatically, we should leave those be. This patch changes all other places.
189 lines
8.0 KiB
XML
189 lines
8.0 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2014 Zbigniew Jędrzejewski-Szmek
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_bus_path_encode">
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<refentryinfo>
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<title>sd_bus_path_encode</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>A monkey with a typewriter</contrib>
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<firstname>Zbigniew</firstname>
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<surname>Jędrzejewski-Szmek</surname>
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<email>zbyszek@in.waw.pl</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_bus_path_encode</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_bus_path_encode</refname>
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<refname>sd_bus_path_encode_many</refname>
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<refname>sd_bus_path_decode</refname>
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<refname>sd_bus_path_decode_many</refname>
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<refpurpose>Convert an external identifier into an object path and back</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_bus_path_encode</function></funcdef>
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<paramdef>const char *<parameter>prefix</parameter></paramdef>
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<paramdef>const char *<parameter>external_id</parameter></paramdef>
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<paramdef>char **<parameter>ret_path</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_path_encode_many</function></funcdef>
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<paramdef>char **<parameter>out</parameter></paramdef>
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<paramdef>const char *<parameter>path_template</parameter></paramdef>
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<paramdef>…</paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_path_decode</function></funcdef>
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<paramdef>const char *<parameter>path</parameter></paramdef>
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<paramdef>const char *<parameter>prefix</parameter></paramdef>
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<paramdef>char **<parameter>ret_external_id</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_path_decode_many</function></funcdef>
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<paramdef>const char *<parameter>path</parameter></paramdef>
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<paramdef>const char *<parameter>path_template</parameter></paramdef>
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<paramdef>…</paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_bus_path_encode()</function> and
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<function>sd_bus_path_decode()</function> convert external
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identifier strings into object paths and back. These functions are
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useful to map application-specific string identifiers of any kind
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into bus object paths in a simple, reversible and safe way.</para>
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<para><function>sd_bus_path_encode()</function> takes a bus path
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prefix and an external identifier string as arguments, plus a
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place to store the returned bus path string. The bus path prefix
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must be a valid bus path, starting with a slash
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<literal>/</literal>, and not ending in one. The external
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identifier string may be in any format, may be the empty string,
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and has no restrictions on the charset — however, it must
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always be <constant>NUL</constant>-terminated. The returned string
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will be the concatenation of the bus path prefix plus an escaped
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version of the external identifier string. This operation may be
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reversed with <function>sd_bus_decode()</function>. It is
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recommended to only use external identifiers that generally
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require little escaping to be turned into valid bus path
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identifiers (for example, by sticking to a 7-bit ASCII character
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set), in order to ensure the resulting bus path is still short and
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easily processed.</para>
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<para><function>sd_bus_path_decode()</function> reverses the
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operation of <function>sd_bus_path_encode()</function> and thus
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regenerates an external identifier string from a bus path. It
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takes a bus path and a prefix string, plus a place to store the
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returned external identifier string. If the bus path does not
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start with the specified prefix, 0 is returned and the returned
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string is set to <constant>NULL</constant>. Otherwise, the
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string following the prefix is unescaped and returned in the
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external identifier string.</para>
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<para>The escaping used will replace all characters which are
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invalid in a bus object path by <literal>_</literal>, followed by a
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hexadecimal value. As a special case, the empty string will be
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replaced by a lone <literal>_</literal>.</para>
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<para><function>sd_bus_path_encode_many()</function> works like
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its counterpart <function>sd_bus_path_encode()</function>, but
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takes a path template as argument and encodes multiple labels
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according to its embedded directives. For each
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<literal>%</literal> character found in the template, the caller
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must provide a string via varargs, which will be encoded and
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embedded at the position of the <literal>%</literal> character.
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Any other character in the template is copied verbatim into the
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encoded path.</para>
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<para><function>sd_bus_path_decode_many()</function> does the
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reverse of <function>sd_bus_path_encode_many()</function>. It
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decodes the passed object path according to the given
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path template. For each <literal>%</literal> character in the
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template, the caller must provide an output storage
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(<literal>char **</literal>) via varargs. The decoded label
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will be stored there. Each <literal>%</literal> character will
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only match the current label. It will never match across labels.
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Furthermore, only a single directive is allowed per label.
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If <literal>NULL</literal> is passed as output storage, the
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label is verified but not returned to the caller.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On success, <function>sd_bus_path_encode()</function>
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returns positive or 0, and a valid bus path in the return
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argument. On success, <function>sd_bus_path_decode()</function>
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returns a positive value if the prefixed matched, or 0 if it
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did not. If the prefix matched, the external identifier is returned
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in the return parameter. If it did not match, NULL is returned in
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the return parameter. On failure, a negative errno-style error
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number is returned by either function. The returned strings must
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be
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<citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>'d
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by the caller.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para><function>sd_bus_path_encode()</function> and
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<function>sd_bus_path_decode()</function> are available as a
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shared library, which can be compiled and linked to with the
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<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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