416 lines
15 KiB
XML
416 lines
15 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2014 Zbigniew Jędrzejewski-Szmek
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_bus_error">
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<refentryinfo>
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<title>sd_bus_error</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>A monkey with a typewriter</contrib>
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<firstname>Zbigniew</firstname>
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<surname>Jędrzejewski-Szmek</surname>
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<email>zbyszek@in.waw.pl</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_bus_error</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_bus_error</refname>
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<refname>sd_bus_error_free</refname>
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<refname>sd_bus_error_set</refname>
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<refname>sd_bus_error_set_const</refname>
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<refname>sd_bus_error_set_errno</refname>
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<refname>sd_bus_error_set_errnof</refname>
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<refname>sd_bus_error_get_errno</refname>
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<refname>sd_bus_error_copy</refname>
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<refname>sd_bus_error_is_set</refname>
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<refname>sd_bus_error_has_name</refname>
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<refpurpose>sd-bus error handling</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
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<funcsynopsisinfo>typedef struct {
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const char *name;
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const char *message;
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...
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} sd_bus_error;</funcsynopsisinfo>
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<para>
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<constant>SD_BUS_ERROR_MAKE_CONST(<replaceable>name</replaceable>, <replaceable>message</replaceable>)</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_NULL</constant>
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</para>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_free</function></funcdef>
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<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_set</function></funcdef>
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<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
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<paramdef>const char *<parameter>name</parameter></paramdef>
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<paramdef>const char *<parameter>message</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_setf</function></funcdef>
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<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
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<paramdef>const char *<parameter>name</parameter></paramdef>
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<paramdef>const char *<parameter>format</parameter></paramdef>
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<paramdef>...</paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_set_const</function></funcdef>
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<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
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<paramdef>const char *<parameter>name</parameter></paramdef>
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<paramdef>const char *<parameter>message</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_set_errno</function></funcdef>
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<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
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<paramdef>int <parameter>error</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_set_errnof</function></funcdef>
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<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
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<paramdef>int <parameter>error</parameter></paramdef>
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<paramdef>const char *<parameter>format</parameter></paramdef>
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<paramdef>...</paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_get_errno</function></funcdef>
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<paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_copy</function></funcdef>
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<paramdef>sd_bus_error *<parameter>dst</parameter></paramdef>
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<paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_is_set</function></funcdef>
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<paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_error_has_name</function></funcdef>
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<paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
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<paramdef>const char *<parameter>name</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<para>
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<constant>SD_BUS_ERROR_FAILED</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_NO_MEMORY</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_SERVICE_UNKNOWN</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_NAME_HAS_NO_OWNER</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_NO_REPLY</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_IO_ERROR</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_BAD_ADDRESS</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_NOT_SUPPORTED</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_LIMITS_EXCEEDED</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_ACCESS_DENIED</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_AUTH_FAILED</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_NO_SERVER</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_TIMEOUT</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_NO_NETWORK</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_ADDRESS_IN_USE</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_DISCONNECTED</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_INVALID_ARGS</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_FILE_NOT_FOUND</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_FILE_EXISTS</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_UNKNOWN_METHOD</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_UNKNOWN_OBJECT</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_UNKNOWN_INTERFACE</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_UNKNOWN_PROPERTY</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_PROPERTY_READ_ONLY</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_UNIX_PROCESS_ID_UNKNOWN</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_INVALID_SIGNATURE</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_INCONSISTENT_MESSAGE</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_MATCH_RULE_NOT_FOUND</constant>
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</para>
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<para>
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<constant>SD_BUS_ERROR_MATCH_RULE_INVALID</constant>
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</para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><structname>sd_bus_error</structname> structure carries
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information for a <filename>sd-bus</filename> error.
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Functions described below can be used to set and query fields in
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this structure. Field <structfield>name</structfield> contains a
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short identifier of an error. It should follow the rules for error
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names described in the D-Bus specification, subsection <ulink
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url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names">Valid
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Names</ulink>. The <structfield>message</structfield> is a human
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readable string describing the details. When no longer necessary,
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resources held by this structure should be destroyed with
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<function>sd_bus_error_free</function>.</para>
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<para><function>sd_bus_error_set</function> will return an
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errno-like negative value returned based on parameter
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<parameter>name</parameter> (see
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<citerefentry><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>).
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Various well-known D-Bus errors are converted to specific values,
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and the remaining ones to <constant>-ENXIO</constant>. Well-known
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D-Bus error names are available as constants
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<constant>SD_BUS_ERROR_FAILED</constant>, etc., listed above. If
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<parameter>name</parameter> is <constant>NULL</constant>, it is is
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assumed that no error occured, and 0 is returned. This means that
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this function may be conveniently used in a
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<function>return</function> statement.</para>
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<para>If <parameter>e</parameter> is not
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<constant>NULL</constant>, <structfield>name</structfield> and
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<structfield>message</structfield> will be filled-in in the
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<structname>sd_bus_error</structname> structure
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<parameter>e</parameter> points at. As described above,
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<parameter>name</parameter> may be <constant>NULL</constant>,
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which is treated as no error. Parameter
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<parameter>message</parameter> may also be
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<constant>NULL</constant>, in which case no message is specified.
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<function>sd_bus_error_set</function> will make internal copies of
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specified strings.</para>
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<para><function>sd_bus_error_setf</function> is similar to
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<function>sd_bus_error_set</function>, but takes a
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<citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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format string and corresponding arguments to generate
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<structname>message</structname>.</para>
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<para><function>sd_bus_error_set_const</function> is similar to
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<function>sd_bus_error_set</function>, but string parameters are
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not copied internally, and must remain valid for the lifetime of
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<parameter>e</parameter>.</para>
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<para><function>sd_bus_error_set_errno</function> will set
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<structfield>name</structfield> based on an errno-like value.
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<citerefentry><refentrytitle>strerror</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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will be used to set <structfield>message</structfield>. Well-known
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D-Bus error names will be used for <structfield>name</structfield>
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if available, otherwise a name in the
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<literal>System.Error</literal> namespace will be generated.
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</para>
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<para><function>sd_bus_error_set_errnof</function> is similar to
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<function>sd_bus_error_set_errno</function>, but in addition to
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<parameter>name</parameter>, takes a
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<citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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format and corresponding arguments.
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<structfield>name</structfield> will be generated from
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<parameter>format</parameter> and the arguments.</para>
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<para><function>sd_bus_error_get_errno</function> is will convert
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<structname>e->name</structname> to an errno-like value using the
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same rules as <function>sd_bus_error_set</function>. If
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<parameter>e</parameter> is <constant>NULL</constant>, 0 will be
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returned.</para>
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<para><function>sd_bus_error_copy</function> will initialize
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<parameter>dst</parameter> using the values in
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<parameter>e</parameter>. If the strings in
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<parameter>e</parameter> were set using
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<function>sd_bus_set_error_const</function>, they will be shared.
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Otherwie they wil be copied.</para>
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<para><function>sd_bus_error_is_set</function> will return
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<constant>true</constant> if <parameter>e</parameter> is
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non-<constant>NULL</constant> and an error has been set,
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<constant>false</constant> otherwise.</para>
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<para><function>sd_bus_error_has_name</function> will return true
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if <parameter>e</parameter> is non-<constant>NULL</constant> and
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an error with the same <parameter>name</parameter> has been set,
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<constant>false</constant> otherwise.</para>
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<para><function>sd_bus_error_free</function> will destroy resources
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held by <parameter>e</parameter>. The parameter itself will not
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be deallocated, and must be
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<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>d
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by the caller if necessary.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>Functions <function>sd_bus_error_set</function>,
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<function>sd_bus_error_setf</function>,
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<function>sd_bus_error_set_const</function>, when successful,
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return the negative errno value corresponding to the
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<parameter>name</parameter> parameter. Functions
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<function>sd_bus_error_set_errno</function> and
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<function>sd_bus_error_set_errnof</function>, when successful,
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return the value of the <parameter>errno</parameter> parameter. If
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an error occurs, one of the negative error values listed below
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will be returned.</para>
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<para><function>sd_bus_error_get_errno</function> returns
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<constant>false</constant> when <parameter>e</parameter> is
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<constant>NULL</constant>, and a positive errno value mapped from
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<parameter>e->name</parameter> otherwise.</para>
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<para><function>sd_bus_error_copy</function> returns 0 or a
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positive integer on success, and one of the negative error values
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listed below otherwise.</para>
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<para><function>sd_bus_error_is_set</function> returns
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<constant>true</constant> when <parameter>e</parameter> and
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<parameter>e->name</parameter> are non-<constant>NULL</constant>,
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<constant>false</constant> otherwise.</para>
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<para><function>sd_bus_error_has_name</function> returns
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<constant>true</constant> when <parameter>e</parameter> is
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non-<constant>NULL</constant> and <parameter>e->name</parameter>
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is equal to <parameter>name</parameter>,
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<constant>false</constant> otherwise.</para>
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</refsect1>
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<refsect1>
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<title>Reference ownership</title>
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<para><structname>sd_bus_error</structname> is not reference
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counted. Users should destroy resources held by it by calling
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<function>sd_bus_error_free</function>.</para>
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</refsect1>
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<refsect1>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><varname>-EINVAL</varname></term>
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<listitem><para>Error was already set in
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<structname>sd_bus_error</structname> structure when one the
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error-setting functions was called.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>-ENOMEM</varname></term>
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<listitem><para>Memory allocation failed.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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||
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<para><function>sd_bus_set_error()</function> and other functions
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described here are available as a shared library, which can be
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compiled and linked to with the
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<constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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||
file.</para>
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</refsect1>
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<refsect1>
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||
<title>See Also</title>
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||
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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||
<citerefentry><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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||
<citerefentry><refentrytitle>strerror</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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