<?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>