1<?xml version='1.0'?>
2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
5
6<refentry id="sd_bus_error_add_map"
7          xmlns:xi="http://www.w3.org/2001/XInclude">
8
9  <refentryinfo>
10    <title>sd_bus_error_add_map</title>
11    <productname>systemd</productname>
12  </refentryinfo>
13
14  <refmeta>
15    <refentrytitle>sd_bus_error_add_map</refentrytitle>
16    <manvolnum>3</manvolnum>
17  </refmeta>
18
19  <refnamediv>
20    <refname>sd_bus_error_add_map</refname>
21    <refname>sd_bus_error_map</refname>
22    <refname>SD_BUS_ERROR_MAP</refname>
23    <refname>SD_BUS_ERROR_END</refname>
24
25    <refpurpose>Additional sd-dbus error mappings</refpurpose>
26  </refnamediv>
27
28  <refsynopsisdiv>
29    <funcsynopsis>
30      <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
31
32      <funcsynopsisinfo>typedef struct {
33        const char *name;
34        int code;
35        …
36} sd_bus_error_map;</funcsynopsisinfo>
37
38    </funcsynopsis>
39
40      <para>
41        <constant>SD_BUS_ERROR_MAP(<replaceable>name</replaceable>, <replaceable>code</replaceable>)</constant>
42      </para>
43      <para>
44        <constant>SD_BUS_ERROR_MAP_END</constant>
45      </para>
46
47      <funcprototype>
48        <funcdef>int <function>sd_bus_error_add_map</function></funcdef>
49        <paramdef>const sd_bus_error_map *<parameter>map</parameter></paramdef>
50      </funcprototype>
51
52  </refsynopsisdiv>
53
54  <refsect1>
55    <title>Description</title>
56
57    <para>The <function>sd_bus_error_add_map()</function> call may be
58    used to register additional mappings for converting D-Bus errors
59    to Linux <varname>errno</varname>-style errors. The mappings
60    defined with this call are consulted by calls such as
61    <citerefentry><refentrytitle>sd_bus_error_set</refentrytitle><manvolnum>3</manvolnum></citerefentry>
62    or
63    <citerefentry><refentrytitle>sd_bus_error_get_errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>. By
64    default, a number of generic, standardized mappings are known, as
65    documented in
66    <citerefentry><refentrytitle>sd-bus-errors</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Use
67    this call to add further, application-specific mappings.</para>
68
69    <para>The function takes a pointer to an array of
70    <structname>sd_bus_error_map</structname> structures. A reference
71    to the specified array is added to the lookup tables for error
72    mappings. Note that the structure is not copied, and that it is hence
73    essential that the array stays available and constant during the
74    entire remaining runtime of the process.</para>
75
76    <para>The mapping array should be put together with a series of
77    <constant>SD_BUS_ERROR_MAP()</constant> macro invocations that
78    take a literal name string and a (positive)
79    <varname>errno</varname>-style error number. The last entry of the
80    array should be an invocation of the
81    <constant>SD_BUS_ERROR_MAP_END</constant> macro. The array should not be
82    put together without use of these two macros.</para>
83
84    <para>Note that the call is idempotent: it is safe to invoke it
85    multiple times with the parameter, which will only add the passed
86    mapping array once.</para>
87
88    <para>Note that the memory allocated by this call is not intended
89    to be freed during the lifetime of the process. It should not be
90    freed explicitly.</para>
91  </refsect1>
92
93  <refsect1>
94    <title>Return Value</title>
95
96    <para><function>sd_bus_error_add_map()</function> returns a
97    positive value when the new array was added to the lookup
98    tables. It returns zero when the same array was already added
99    before. On error, a negative <varname>errno</varname>-style error
100    code is returned. See below for known error codes.</para>
101
102    <refsect2>
103      <title>Errors</title>
104
105      <para>Returned errors may indicate the following problems:</para>
106
107      <variablelist>
108
109        <varlistentry>
110          <term><constant>-EINVAL</constant></term>
111
112          <listitem><para>The specified mapping array is invalid.</para></listitem>
113        </varlistentry>
114
115        <varlistentry>
116          <term><constant>-ENOMEM</constant></term>
117
118          <listitem><para>Memory allocation failed.</para></listitem>
119        </varlistentry>
120      </variablelist>
121    </refsect2>
122  </refsect1>
123
124  <xi:include href="libsystemd-pkgconfig.xml" />
125
126  <refsect1>
127    <title>See Also</title>
128
129    <para>
130      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
131      <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
132      <citerefentry><refentrytitle>sd_bus_error</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
133      <citerefentry><refentrytitle>sd-bus-errors</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
134      <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
135      <citerefentry project='die-net'><refentrytitle>strerror_r</refentrytitle><manvolnum>3</manvolnum></citerefentry>
136    </para>
137  </refsect1>
138
139</refentry>
140