<?xml version='1.0'?> <!--*-nxml-*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. Copyright 2014 Zbigniew Jędrzejewski-Szmek systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. --> <refentry id="sd_bus_error" conditional="ENABLE_KDBUS"> <refentryinfo> <title>sd_bus_error</title> <productname>systemd</productname> <authorgroup> <author> <contrib>A monkey with a typewriter</contrib> <firstname>Zbigniew</firstname> <surname>Jędrzejewski-Szmek</surname> <email>zbyszek@in.waw.pl</email> </author> </authorgroup> </refentryinfo> <refmeta> <refentrytitle>sd_bus_error</refentrytitle> <manvolnum>3</manvolnum> </refmeta> <refnamediv> <refname>sd_bus_error</refname> <refname>sd_bus_error_free</refname> <refname>sd_bus_error_set</refname> <refname>sd_bus_error_set_const</refname> <refname>sd_bus_error_set_errno</refname> <refname>sd_bus_error_set_errnof</refname> <refname>sd_bus_error_get_errno</refname> <refname>sd_bus_error_copy</refname> <refname>sd_bus_error_is_set</refname> <refname>sd_bus_error_has_name</refname> <refpurpose>sd-bus error handling</refpurpose> </refnamediv> <refsynopsisdiv> <funcsynopsis> <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> <funcsynopsisinfo>typedef struct { const char *name; const char *message; ... } sd_bus_error;</funcsynopsisinfo> <para> <constant>SD_BUS_ERROR_MAKE_CONST(<replaceable>name</replaceable>, <replaceable>message</replaceable>)</constant> </para> <para> <constant>SD_BUS_ERROR_NULL</constant> </para> <funcprototype> <funcdef>int <function>sd_bus_error_free</function></funcdef> <paramdef>sd_bus_error *<parameter>e</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>int <function>sd_bus_error_set</function></funcdef> <paramdef>sd_bus_error *<parameter>e</parameter></paramdef> <paramdef>const char *<parameter>name</parameter></paramdef> <paramdef>const char *<parameter>message</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>int <function>sd_bus_error_setf</function></funcdef> <paramdef>sd_bus_error *<parameter>e</parameter></paramdef> <paramdef>const char *<parameter>name</parameter></paramdef> <paramdef>const char *<parameter>format</parameter></paramdef> <paramdef>...</paramdef> </funcprototype> <funcprototype> <funcdef>int <function>sd_bus_error_set_const</function></funcdef> <paramdef>sd_bus_error *<parameter>e</parameter></paramdef> <paramdef>const char *<parameter>name</parameter></paramdef> <paramdef>const char *<parameter>message</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>int <function>sd_bus_error_set_errno</function></funcdef> <paramdef>sd_bus_error *<parameter>e</parameter></paramdef> <paramdef>int <parameter>error</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>int <function>sd_bus_error_set_errnof</function></funcdef> <paramdef>sd_bus_error *<parameter>e</parameter></paramdef> <paramdef>int <parameter>error</parameter></paramdef> <paramdef>const char *<parameter>format</parameter></paramdef> <paramdef>...</paramdef> </funcprototype> <funcprototype> <funcdef>int <function>sd_bus_error_get_errno</function></funcdef> <paramdef>const sd_bus_error *<parameter>e</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>int <function>sd_bus_error_copy</function></funcdef> <paramdef>sd_bus_error *<parameter>dst</parameter></paramdef> <paramdef>const sd_bus_error *<parameter>e</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>int <function>sd_bus_error_is_set</function></funcdef> <paramdef>const sd_bus_error *<parameter>e</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>int <function>sd_bus_error_has_name</function></funcdef> <paramdef>const sd_bus_error *<parameter>e</parameter></paramdef> <paramdef>const char *<parameter>name</parameter></paramdef> </funcprototype> </funcsynopsis> <para> <constant>SD_BUS_ERROR_FAILED</constant> </para> <para> <constant>SD_BUS_ERROR_NO_MEMORY</constant> </para> <para> <constant>SD_BUS_ERROR_SERVICE_UNKNOWN</constant> </para> <para> <constant>SD_BUS_ERROR_NAME_HAS_NO_OWNER</constant> </para> <para> <constant>SD_BUS_ERROR_NO_REPLY</constant> </para> <para> <constant>SD_BUS_ERROR_IO_ERROR</constant> </para> <para> <constant>SD_BUS_ERROR_BAD_ADDRESS</constant> </para> <para> <constant>SD_BUS_ERROR_NOT_SUPPORTED</constant> </para> <para> <constant>SD_BUS_ERROR_LIMITS_EXCEEDED</constant> </para> <para> <constant>SD_BUS_ERROR_ACCESS_DENIED</constant> </para> <para> <constant>SD_BUS_ERROR_AUTH_FAILED</constant> </para> <para> <constant>SD_BUS_ERROR_NO_SERVER</constant> </para> <para> <constant>SD_BUS_ERROR_TIMEOUT</constant> </para> <para> <constant>SD_BUS_ERROR_NO_NETWORK</constant> </para> <para> <constant>SD_BUS_ERROR_ADDRESS_IN_USE</constant> </para> <para> <constant>SD_BUS_ERROR_DISCONNECTED</constant> </para> <para> <constant>SD_BUS_ERROR_INVALID_ARGS</constant> </para> <para> <constant>SD_BUS_ERROR_FILE_NOT_FOUND</constant> </para> <para> <constant>SD_BUS_ERROR_FILE_EXISTS</constant> </para> <para> <constant>SD_BUS_ERROR_UNKNOWN_METHOD</constant> </para> <para> <constant>SD_BUS_ERROR_UNKNOWN_OBJECT</constant> </para> <para> <constant>SD_BUS_ERROR_UNKNOWN_INTERFACE</constant> </para> <para> <constant>SD_BUS_ERROR_UNKNOWN_PROPERTY</constant> </para> <para> <constant>SD_BUS_ERROR_PROPERTY_READ_ONLY</constant> </para> <para> <constant>SD_BUS_ERROR_UNIX_PROCESS_ID_UNKNOWN</constant> </para> <para> <constant>SD_BUS_ERROR_INVALID_SIGNATURE</constant> </para> <para> <constant>SD_BUS_ERROR_INCONSISTENT_MESSAGE</constant> </para> <para> <constant>SD_BUS_ERROR_MATCH_RULE_NOT_FOUND</constant> </para> <para> <constant>SD_BUS_ERROR_MATCH_RULE_INVALID</constant> </para> </refsynopsisdiv> <refsect1> <title>Description</title> <para>The <structname>sd_bus_error</structname> structure carries information for a <filename>sd-bus</filename> error. Functions described below can be used to set and query fields in this structure. The <structfield>name</structfield> field contains a short identifier of an error. It should follow the rules for error names described in the D-Bus specification, subsection <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names">Valid Names</ulink>. The <structfield>message</structfield> is a human readable string describing the details. When no longer necessary, resources held by this structure should be destroyed with <function>sd_bus_error_free</function>.</para> <para><function>sd_bus_error_set</function> will return an errno-like negative value returned based on parameter <parameter>name</parameter> (see <citerefentry><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>). Various well-known D-Bus errors are converted to specific values, and the remaining ones to <constant>-ENXIO</constant>. Well-known D-Bus error names are available as constants <constant>SD_BUS_ERROR_FAILED</constant>, etc., listed above. If <parameter>name</parameter> is <constant>NULL</constant>, it is assumed that no error occured, and 0 is returned. This means that this function may be conveniently used in a <function>return</function> statement.</para> <para>If <parameter>e</parameter> is not <constant>NULL</constant>, <structfield>name</structfield> and <structfield>message</structfield> in the <structname>sd_bus_error</structname> structure <parameter>e</parameter> points at will be filled in. As described above, <parameter>name</parameter> may be <constant>NULL</constant>, which is treated as no error. Parameter <parameter>message</parameter> may also be <constant>NULL</constant>, in which case no message is specified. <function>sd_bus_error_set</function> will make internal copies of specified strings.</para> <para><function>sd_bus_error_setf</function> is similar to <function>sd_bus_error_set</function>, but takes a <citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry> format string and corresponding arguments to generate <structname>message</structname>.</para> <para><function>sd_bus_error_set_const</function> is similar to <function>sd_bus_error_set</function>, but string parameters are not copied internally, and must remain valid for the lifetime of <parameter>e</parameter>.</para> <para><function>sd_bus_error_set_errno</function> will set <structfield>name</structfield> based on an errno-like value. <citerefentry><refentrytitle>strerror</refentrytitle><manvolnum>3</manvolnum></citerefentry> will be used to set <structfield>message</structfield>. Well-known D-Bus error names will be used for <structfield>name</structfield> if available, otherwise a name in the <literal>System.Error</literal> namespace will be generated. </para> <para><function>sd_bus_error_set_errnof</function> is similar to <function>sd_bus_error_set_errno</function>, but in addition to <parameter>name</parameter>, takes a <citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry> format and corresponding arguments. <structfield>name</structfield> will be generated from <parameter>format</parameter> and the arguments.</para> <para><function>sd_bus_error_get_errno</function> is will convert <structname>e->name</structname> to an errno-like value using the same rules as <function>sd_bus_error_set</function>. If <parameter>e</parameter> is <constant>NULL</constant>, 0 will be returned.</para> <para><function>sd_bus_error_copy</function> will initialize <parameter>dst</parameter> using the values in <parameter>e</parameter>. If the strings in <parameter>e</parameter> were set using <function>sd_bus_set_error_const</function>, they will be shared. Otherwise, they will be copied.</para> <para><function>sd_bus_error_is_set</function> will return <constant>true</constant> if <parameter>e</parameter> is non-<constant>NULL</constant> and an error has been set, <constant>false</constant> otherwise.</para> <para><function>sd_bus_error_has_name</function> will return true if <parameter>e</parameter> is non-<constant>NULL</constant> and an error with the same <parameter>name</parameter> has been set, <constant>false</constant> otherwise.</para> <para><function>sd_bus_error_free</function> will destroy resources held by <parameter>e</parameter>. The parameter itself will not be deallocated, and must be <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>d by the caller if necessary.</para> </refsect1> <refsect1> <title>Return Value</title> <para>Functions <function>sd_bus_error_set</function>, <function>sd_bus_error_setf</function>, <function>sd_bus_error_set_const</function>, when successful, return the negative errno value corresponding to the <parameter>name</parameter> parameter. Functions <function>sd_bus_error_set_errno</function> and <function>sd_bus_error_set_errnof</function>, when successful, return the value of the <parameter>errno</parameter> parameter. If an error occurs, one of the negative error values listed below will be returned.</para> <para><function>sd_bus_error_get_errno</function> returns <constant>false</constant> when <parameter>e</parameter> is <constant>NULL</constant>, and a positive errno value mapped from <parameter>e->name</parameter> otherwise.</para> <para><function>sd_bus_error_copy</function> returns 0 or a positive integer on success, and one of the negative error values listed below otherwise.</para> <para><function>sd_bus_error_is_set</function> returns <constant>true</constant> when <parameter>e</parameter> and <parameter>e->name</parameter> are non-<constant>NULL</constant>, <constant>false</constant> otherwise.</para> <para><function>sd_bus_error_has_name</function> returns <constant>true</constant> when <parameter>e</parameter> is non-<constant>NULL</constant> and <parameter>e->name</parameter> is equal to <parameter>name</parameter>, <constant>false</constant> otherwise.</para> </refsect1> <refsect1> <title>Reference ownership</title> <para><structname>sd_bus_error</structname> is not reference counted. Users should destroy resources held by it by calling <function>sd_bus_error_free</function>.</para> </refsect1> <refsect1> <title>Errors</title> <para>Returned errors may indicate the following problems:</para> <variablelist> <varlistentry> <term><varname>-EINVAL</varname></term> <listitem><para>Error was already set in <structname>sd_bus_error</structname> structure when one the error-setting functions was called.</para></listitem> </varlistentry> <varlistentry> <term><varname>-ENOMEM</varname></term> <listitem><para>Memory allocation failed.</para></listitem> </varlistentry> </variablelist> </refsect1> <refsect1> <title>Notes</title> <para><function>sd_bus_set_error()</function> and other functions described here are available as a shared library, which can be compiled and linked to with the <constant>libsystemd</constant> <citerefentry><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>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>strerror</refentrytitle><manvolnum>3</manvolnum></citerefentry> </para> </refsect1> </refentry>