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<refentry id="sd_bus_error_add_map">

  <refentryinfo>
    <title>sd_bus_error_add_map</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>Developer</contrib>
        <firstname>Lennart</firstname>
        <surname>Poettering</surname>
        <email>lennart@poettering.net</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd_bus_error_add_map</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd_bus_error_add_map</refname>
    <refname>sd_bus_error_map</refname>
    <refname>SD_BUS_ERROR_MAP</refname>
    <refname>SD_BUS_ERROR_END</refname>

    <refpurpose>Additional sd-dbus error mappings</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>

      <funcsynopsisinfo>typedef struct {
        const char *name;
        int code;
        …
} sd_bus_error_map;</funcsynopsisinfo>

    </funcsynopsis>

      <para>
        <constant>SD_BUS_ERROR_MAP(<replaceable>name</replaceable>, <replaceable>code</replaceable>)</constant>
      </para>
      <para>
        <constant>SD_BUS_ERROR_MAP_END</constant>
      </para>

      <funcprototype>
        <funcdef>int <function>sd_bus_error_add_map</function></funcdef>
        <paramdef>const sd_bus_map *<parameter>map</parameter></paramdef>
      </funcprototype>

  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>The <function>sd_bus_error_add_map()</function> call may be
    used to register additional mappings for converting D-Bus errors
    to Linux <varname>errno</varname>-style errors. The mappings
    defined with this call are consulted by calls such as
    <citerefentry><refentrytitle>sd_bus_error_set</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    or
    <citerefentry><refentrytitle>sd_bus_error_get_errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>. By
    default, a number of generic, standardized mappings are known, as
    documented in
    <citerefentry><refentrytitle>sd-bus-errors</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Use
    this call to add further, application-specific mappings.</para>

    <para>The function takes a pointer to an array of
    <structname>sd_bus_error_map</structname> structures. A reference
    to the specified array is added to the lookup tables for error
    mappings. Note that the structure is not copied, and that it is hence
    essential that the array stays available and constant during the
    entire remaining runtime of the process.</para>

    <para>The mapping array should be put together with a series of
    <constant>SD_BUS_ERROR_MAP()</constant> macro invocations that
    take a literal name string and a (positive)
    <varname>errno</varname>-style error number. The last entry of the
    array should be an invocation of the
    <constant>SD_BUS_ERROR_MAP_END</constant> macro. The array should not be
    put together without use of these two macros.</para>

    <para>Note that the call is idempotent: it is safe to invoke it
    multiple times with the parameter, which will only add the passed
    mapping array once.</para>

    <para>Note that the memory allocated by this call is not intended
    to be freed during the lifetime of the process. It should not be
    freed explicitly.</para>
  </refsect1>

  <refsect1>
    <title>Return Value</title>

    <para><function>sd_bus_error_add_map()</function> returns a
    positive value when the new array was added to the lookup
    tables. It returns zero when the same array was already added
    before. On error, a negative <varname>errno</varname>-style error
    code is returned. See below for known error codes.</para>
  </refsect1>

  <refsect1>
    <title>Errors</title>

    <para>Returned errors may indicate the following problems:</para>

    <variablelist>

      <varlistentry>
        <term><constant>-EINVAL</constant></term>

        <listitem><para>The specified mapping array is invalid.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>-ENOMEM</constant></term>

        <listitem><para>Memory allocation failed.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Notes</title>

    <para>The various error definitions described here are available
    as a shared library, which can be compiled and linked to with the
    <constant>libsystemd</constant> <citerefentry
    project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    file.</para>
  </refsect1>

  <refsect1>
    <title>See Also</title>

    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_bus_error</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd-bus-errors</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry project='die-net'><refentrytitle>strerror_r</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>
