man/sd_bus_path_encode.xml

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  11   Copyright 2014 Zbigniew Jędrzejewski-Szmek
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  26
  27 <refentry id="sd_bus_path_encode">
  28
  29   <refentryinfo>
  30     <title>sd_bus_path_encode</title>
  31     <productname>systemd</productname>
  32
  33     <authorgroup>
  34       <author>
  35         <contrib>A monkey with a typewriter</contrib>
  36         <firstname>Zbigniew</firstname>
  37         <surname>Jędrzejewski-Szmek</surname>
  38         <email>zbyszek@in.waw.pl</email>
  39       </author>
  40     </authorgroup>
  41   </refentryinfo>
  42
  43   <refmeta>
  44     <refentrytitle>sd_bus_path_encode</refentrytitle>
  45     <manvolnum>3</manvolnum>
  46   </refmeta>
  47
  48   <refnamediv>
  49     <refname>sd_bus_path_encode</refname>
  50     <refname>sd_bus_path_decode</refname>
  51
  52     <refpurpose>Convert an external identifier into an object path and back</refpurpose>
  53   </refnamediv>
  54
  55   <refsynopsisdiv>
  56     <funcsynopsis>
  57       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  58
  59       <funcprototype>
  60         <funcdef>int <function>sd_bus_path_encode</function></funcdef>
  61         <paramdef>const char *<parameter>prefix</parameter></paramdef>
  62         <paramdef>const char *<parameter>external_id</parameter></paramdef>
  63         <paramdef>char **<parameter>ret_path</parameter></paramdef>
  64       </funcprototype>
  65
  66       <funcprototype>
  67         <funcdef>int <function>sd_bus_path_decode</function></funcdef>
  68         <paramdef>const char *<parameter>path</parameter></paramdef>
  69         <paramdef>const char *<parameter>prefix</parameter></paramdef>
  70         <paramdef>char **<parameter>ret_external_id</parameter></paramdef>
  71       </funcprototype>
  72     </funcsynopsis>
  73   </refsynopsisdiv>
  74
  75   <refsect1>
  76     <title>Description</title>
  77
  78     <para><function>sd_bus_path_encode()</function> and
  79     <function>sd_bus_path_decode()</function> convert external
  80     identifier strings into object paths and back. These functions are
  81     useful to map application-specific string identifiers of any kind
  82     into bus object paths in a simple, reversible and safe way.</para>
  83
  84     <para><function>sd_bus_path_encode()</function> takes a bus path
  85     prefix and an external identifier string as arguments, plus a
  86     place to store the returned bus path string. The bus path prefix
  87     must be a valid bus path, starting with a slash
  88     <literal>/</literal>, and not ending in one. The external
  89     identifier string may be in any format, may be the empty string,
  90     and has no restrictions on the charset — however, it must
  91     always be <constant>NUL</constant>-terminated. The returned string
  92     will be the concatenation of the bus path prefix plus an escaped
  93     version of the external identifier string. This operation may be
  94     reversed with <function>sd_bus_decode()</function>. It is
  95     recommended to only use external identifiers that generally
  96     require little escaping to be turned into valid bus path
  97     identifiers (for example, by sticking to a 7-bit ASCII character
  98     set), in order to ensure the resulting bus path is still short and
  99     easily processed.</para>
 100
 101     <para><function>sd_bus_path_decode()</function> reverses the
 102     operation of <function>sd_bus_path_encode()</function> and thus
 103     regenerates an external identifier string from a bus path. It
 104     takes a bus path and a prefix string, plus a place to store the
 105     returned external identifier string. If the bus path does not
 106     start with the specified prefix, 0 is returned and the returned
 107     string is set to <constant>NULL</constant>. Otherwise, the
 108     string following the prefix is unescaped and returned in the
 109     external identifier string.</para>
 110
 111     <para>The escaping used will replace all characters which are
 112     invalid in a bus object path by <literal>_</literal>, followed by a
 113     hexadecimal value. As a special case, the empty string will be
 114     replaced by a lone <literal>_</literal>.</para>
 115   </refsect1>
 116
 117   <refsect1>
 118     <title>Return Value</title>
 119
 120     <para>On success, <function>sd_bus_path_encode()</function>
 121     returns positive or 0, and a valid bus path in the return
 122     argument. On success, <function>sd_bus_path_decode()</function>
 123     returns a positive value if the prefixed matched, or 0 if it
 124     did not. If the prefix matched, the external identifier is returned
 125     in the return parameter. If it did not match, NULL is returned in
 126     the return parameter. On failure, a negative errno-style error
 127     number is returned by either function. The returned strings must
 128     be
 129     <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>'d
 130     by the caller.</para>
 131   </refsect1>
 132
 133   <refsect1>
 134     <title>Notes</title>
 135
 136     <para><function>sd_bus_path_encode()</function> and
 137     <function>sd_bus_path_decode()</function> are available as a
 138     shared library, which can be compiled and linked to with the
 139     <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 140     file.</para>
 141   </refsect1>
 142
 143   <refsect1>
 144     <title>See Also</title>
 145
 146     <para>
 147       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 148       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 149       <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 150     </para>
 151   </refsect1>
 152
 153 </refentry>