man/sd_bus_error_add_map.xml

   1 <?xml version='1.0'?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7 -->
   8
   9 <refentry id="sd_bus_error_add_map"
  10           xmlns:xi="http://www.w3.org/2001/XInclude">
  11
  12   <refentryinfo>
  13     <title>sd_bus_error_add_map</title>
  14     <productname>systemd</productname>
  15   </refentryinfo>
  16
  17   <refmeta>
  18     <refentrytitle>sd_bus_error_add_map</refentrytitle>
  19     <manvolnum>3</manvolnum>
  20   </refmeta>
  21
  22   <refnamediv>
  23     <refname>sd_bus_error_add_map</refname>
  24     <refname>sd_bus_error_map</refname>
  25     <refname>SD_BUS_ERROR_MAP</refname>
  26     <refname>SD_BUS_ERROR_END</refname>
  27
  28     <refpurpose>Additional sd-dbus error mappings</refpurpose>
  29   </refnamediv>
  30
  31   <refsynopsisdiv>
  32     <funcsynopsis>
  33       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  34
  35       <funcsynopsisinfo>typedef struct {
  36         const char *name;
  37         int code;
  38         …
  39 } sd_bus_error_map;</funcsynopsisinfo>
  40
  41     </funcsynopsis>
  42
  43       <para>
  44         <constant>SD_BUS_ERROR_MAP(<replaceable>name</replaceable>, <replaceable>code</replaceable>)</constant>
  45       </para>
  46       <para>
  47         <constant>SD_BUS_ERROR_MAP_END</constant>
  48       </para>
  49
  50       <funcprototype>
  51         <funcdef>int <function>sd_bus_error_add_map</function></funcdef>
  52         <paramdef>const sd_bus_map *<parameter>map</parameter></paramdef>
  53       </funcprototype>
  54
  55   </refsynopsisdiv>
  56
  57   <refsect1>
  58     <title>Description</title>
  59
  60     <para>The <function>sd_bus_error_add_map()</function> call may be
  61     used to register additional mappings for converting D-Bus errors
  62     to Linux <varname>errno</varname>-style errors. The mappings
  63     defined with this call are consulted by calls such as
  64     <citerefentry><refentrytitle>sd_bus_error_set</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  65     or
  66     <citerefentry><refentrytitle>sd_bus_error_get_errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>. By
  67     default, a number of generic, standardized mappings are known, as
  68     documented in
  69     <citerefentry><refentrytitle>sd-bus-errors</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Use
  70     this call to add further, application-specific mappings.</para>
  71
  72     <para>The function takes a pointer to an array of
  73     <structname>sd_bus_error_map</structname> structures. A reference
  74     to the specified array is added to the lookup tables for error
  75     mappings. Note that the structure is not copied, and that it is hence
  76     essential that the array stays available and constant during the
  77     entire remaining runtime of the process.</para>
  78
  79     <para>The mapping array should be put together with a series of
  80     <constant>SD_BUS_ERROR_MAP()</constant> macro invocations that
  81     take a literal name string and a (positive)
  82     <varname>errno</varname>-style error number. The last entry of the
  83     array should be an invocation of the
  84     <constant>SD_BUS_ERROR_MAP_END</constant> macro. The array should not be
  85     put together without use of these two macros.</para>
  86
  87     <para>Note that the call is idempotent: it is safe to invoke it
  88     multiple times with the parameter, which will only add the passed
  89     mapping array once.</para>
  90
  91     <para>Note that the memory allocated by this call is not intended
  92     to be freed during the lifetime of the process. It should not be
  93     freed explicitly.</para>
  94   </refsect1>
  95
  96   <refsect1>
  97     <title>Return Value</title>
  98
  99     <para><function>sd_bus_error_add_map()</function> returns a
 100     positive value when the new array was added to the lookup
 101     tables. It returns zero when the same array was already added
 102     before. On error, a negative <varname>errno</varname>-style error
 103     code is returned. See below for known error codes.</para>
 104   </refsect1>
 105
 106   <refsect1>
 107     <title>Errors</title>
 108
 109     <para>Returned errors may indicate the following problems:</para>
 110
 111     <variablelist>
 112
 113       <varlistentry>
 114         <term><constant>-EINVAL</constant></term>
 115
 116         <listitem><para>The specified mapping array is invalid.</para></listitem>
 117       </varlistentry>
 118
 119       <varlistentry>
 120         <term><constant>-ENOMEM</constant></term>
 121
 122         <listitem><para>Memory allocation failed.</para></listitem>
 123       </varlistentry>
 124     </variablelist>
 125   </refsect1>
 126
 127   <xi:include href="libsystemd-pkgconfig.xml" />
 128
 129   <refsect1>
 130     <title>See Also</title>
 131
 132     <para>
 133       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 134       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 135       <citerefentry><refentrytitle>sd_bus_error</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 136       <citerefentry><refentrytitle>sd-bus-errors</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 137       <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 138       <citerefentry project='die-net'><refentrytitle>strerror_r</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 139     </para>
 140   </refsect1>
 141
 142 </refentry>