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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_bus_message_new_method_error"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_message_new_method_error</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_message_new_method_error</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_message_new_method_error</refname>
<refname>sd_bus_message_new_method_errorf</refname>
<refname>sd_bus_message_new_method_errno</refname>
<refname>sd_bus_message_new_method_errnof</refname>
<refpurpose>Create an error reply for a method call</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int sd_bus_message_new_method_error</funcdef>
<paramdef>sd_bus_message *<parameter>call</parameter></paramdef>
<paramdef>sd_bus_message **<parameter>m</parameter></paramdef>
<paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int sd_bus_message_new_method_errorf</funcdef>
<paramdef>sd_bus_message *<parameter>call</parameter></paramdef>
<paramdef>sd_bus_message **<parameter>m</parameter></paramdef>
<paramdef>const char *<parameter>name</parameter></paramdef>
<paramdef>const char *<parameter>format</parameter></paramdef>
<paramdef>…</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int sd_bus_message_new_method_errno</funcdef>
<paramdef>sd_bus_message *<parameter>call</parameter></paramdef>
<paramdef>sd_bus_message **<parameter>m</parameter></paramdef>
<paramdef>int <parameter>error</parameter></paramdef>
<paramdef>const sd_bus_error *<parameter>p</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int sd_bus_message_new_method_errnof</funcdef>
<paramdef>sd_bus_message *<parameter>call</parameter></paramdef>
<paramdef>sd_bus_message **<parameter>m</parameter></paramdef>
<paramdef>int <parameter>error</parameter></paramdef>
<paramdef>const char *<parameter>format</parameter></paramdef>
<paramdef>…</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>The <function>sd_bus_message_new_method_error()</function> function creates
a new bus message object that is an error reply to the
<parameter>call</parameter> message, and returns it in the
<parameter>m</parameter> output parameter. The error information from error
<parameter>e</parameter> is appended: the <parameter>name</parameter> field of
<parameter>e</parameter> is used as the error identifier in the reply header (for
example an error name such as
<literal>org.freedesktop.DBus.Error.NotSupported</literal> or the equivalent
symbolic <constant>SD_BUS_ERROR_NOT_SUPPORTED</constant>), and the
<parameter>message</parameter> field is set as the human readable error message
string if present. The error <parameter>e</parameter> must have the
<parameter>name</parameter> field set, see
<citerefentry><refentrytitle>sd_bus_error_is_set</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
<para>The <function>sd_bus_message_new_method_errorf()</function> function
creates an error reply similarly to
<function>sd_bus_message_new_method_error()</function>, but instead of a ready
error structure, it takes an error identifier string <parameter>name</parameter>,
plus a <citerefentry
project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
format string <parameter>format</parameter> and corresponding arguments. An error
reply is sent with the error identifier <parameter>name</parameter> and the
formatted string as the message. <parameter>name</parameter> and
<parameter>format</parameter> must not be <constant>NULL</constant>.
</para>
<para>The <function>sd_bus_message_new_method_errno()</function> function creates
an error reply similarly to
<function>sd_bus_message_new_method_error()</function>, but in addition to the
error structure <parameter>p</parameter>, it takes an
<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
error value in parameter <parameter>error</parameter>. If the error
<parameter>p</parameter> is set (see
<citerefentry><refentrytitle>sd_bus_error_is_set</refentrytitle><manvolnum>3</manvolnum></citerefentry>),
it is used in the reply. Otherwise, <parameter>error</parameter> is translated to
an error identifier and used to create a new error structure using
<citerefentry><refentrytitle>sd_bus_error_set_errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and that is used in the reply. (If <parameter>error</parameter> is zero, no error
is actually set, and an error reply with no information is created.)</para>
<para>The <function>sd_bus_message_new_method_errnof()</function> function
creates an error reply similarly to
<function>sd_bus_message_new_method_error()</function>. It takes an
<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
error value in parameter <parameter>error</parameter>, plus a <citerefentry
project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
format string <parameter>format</parameter> and corresponding arguments.
<literal>%m</literal> may be used in the format string to refer to the error
string corresponding to the specified errno code. The error message is initialized
using the error identifier generated from <constant>error</constant> and the
formatted string. (If <parameter>error</parameter> is zero, no error is actually
set, and an error reply with no information is created.)</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>These functions return 0 if the error reply was successfully created, and a
negative errno-style error code otherwise.</para>
<refsect2 id='errors'>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>The call message <parameter>call</parameter> or the output
parameter <parameter>m</parameter> are <constant>NULL</constant>.</para>
<para>Message <parameter>call</parameter> is not a method call
message.</para>
<para>The error <parameter>e</parameter> parameter to
<function>sd_bus_message_new_method_error()</function> is not set, see
<citerefentry><refentrytitle>sd_bus_error_is_set</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>-EPERM</constant></term>
<listitem><para>Message <parameter>call</parameter> has been sealed.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOTCONN</constant></term>
<listitem><para>The bus to which message <parameter>call</parameter> is
attached is not connected.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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