1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_bus_path_encode" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_path_encode</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_path_encode</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_path_encode</refname>
<refname>sd_bus_path_encode_many</refname>
<refname>sd_bus_path_decode</refname>
<refname>sd_bus_path_decode_many</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_encode_many</function></funcdef>
<paramdef>char **<parameter>out</parameter></paramdef>
<paramdef>const char *<parameter>path_template</parameter></paramdef>
<paramdef>…</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>
<funcprototype>
<funcdef>int <function>sd_bus_path_decode_many</function></funcdef>
<paramdef>const char *<parameter>path</parameter></paramdef>
<paramdef>const char *<parameter>path_template</parameter></paramdef>
<paramdef>…</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_path_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>
<para><function>sd_bus_path_encode_many()</function> works like
its counterpart <function>sd_bus_path_encode()</function>, but
takes a path template as argument and encodes multiple labels
according to its embedded directives. For each
<literal>%</literal> character found in the template, the caller
must provide a string via varargs, which will be encoded and
embedded at the position of the <literal>%</literal> character.
Any other character in the template is copied verbatim into the
encoded path.</para>
<para><function>sd_bus_path_decode_many()</function> does the
reverse of <function>sd_bus_path_encode_many()</function>. It
decodes the passed object path according to the given
path template. For each <literal>%</literal> character in the
template, the caller must provide an output storage
(<literal>char **</literal>) via varargs. The decoded label
will be stored there. Each <literal>%</literal> character will
only match the current label. It will never match across labels.
Furthermore, only a single directive is allowed per label.
If <constant>NULL</constant> is passed as output storage, the
label is verified but not returned to the caller.</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, <constant>NULL</constant> 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>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>History</title>
<para><function>sd_bus_path_encode()</function> and
<function>sd_bus_path_decode()</function> were added in version 211.</para>
<para><function>sd_bus_path_encode_many()</function> and
<function>sd_bus_path_decode_many()</function> were added in version 227.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>
|
