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sd-bus objects use hashmaps, which use module-global state, so it is not safe to pass a sd-bus object created by a module instance to another module instance (e.g.: when two libraries static linking sd-bus are pulled in a single process). Initialize a random per-module origin id and store it in the object, and compare it when entering a public API, and error out if they don't match, together with the PID.
250 lines
11 KiB
XML
250 lines
11 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="sd_bus_set_description" xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_bus_set_description</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_bus_set_description</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_set_description</refname>
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<refname>sd_bus_get_description</refname>
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<refname>sd_bus_set_anonymous</refname>
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<refname>sd_bus_is_anonymous</refname>
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<refname>sd_bus_set_trusted</refname>
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<refname>sd_bus_is_trusted</refname>
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<refname>sd_bus_set_allow_interactive_authorization</refname>
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<refname>sd_bus_get_allow_interactive_authorization</refname>
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<refname>sd_bus_get_scope</refname>
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<refname>sd_bus_get_tid</refname>
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<refname>sd_bus_get_unique_name</refname>
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<refpurpose>Set or query properties of a bus object</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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<funcprototype>
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<funcdef>int <function>sd_bus_set_description</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>const char *<parameter>description</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_get_description</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>const char **<parameter>description</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_set_anonymous</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>int <parameter>b</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_is_anonymous</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_set_trusted</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>int <parameter>b</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_is_trusted</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_set_allow_interactive_authorization</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>int <parameter>b</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_get_allow_interactive_authorization</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_get_scope</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>const char **<parameter>scope</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_get_tid</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>pid_t *<parameter>tid</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_get_unique_name</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>const char **<parameter>unique</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_bus_set_description()</function> sets the description string that is used in
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logging to the specified string. The string is copied internally and freed when the bus object
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is deallocated. The <parameter>description</parameter> argument may be
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<constant>NULL</constant>, in which case the description is unset. This function must be called
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before the bus is started.</para>
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<para><function>sd_bus_get_description()</function> returns a description string in
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<parameter>description</parameter>. This string may have been previously set with
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<function>sd_bus_set_description()</function> or
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<citerefentry><refentrytitle>sd_bus_open_with_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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or similar. If not set this way, a default string like <literal>system</literal> or
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<literal>user</literal> will be returned for the system or user buses, and
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<constant>-ENXIO</constant> otherwise.</para>
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<para><function>sd_bus_set_anonymous()</function> enables or disables "anonymous authentication",
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i.e. lack of authentication, of the bus peer. This function must be called before the bus is
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started. See the
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<ulink url="view-source:https://dbus.freedesktop.org/doc/dbus-specification.html#auth-mechanisms">
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Authentication Mechanisms</ulink> section of the D-Bus specification for details.</para>
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<para><function>sd_bus_is_anonymous()</function> returns true if the bus connection allows
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anonymous authentication (in the sense described in previous paragraph).</para>
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<para><function>sd_bus_set_trusted()</function> sets the "trusted" state on the
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<parameter>bus</parameter> object. If true, all connections on the bus are trusted and access to
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all privileged and unprivileged methods is granted. This function must be called before the bus
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is started.</para>
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<para><function>sd_bus_is_trusted()</function> returns true if the bus connection is trusted (in
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the sense described in previous paragraph).</para>
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<para><function>sd_bus_set_allow_interactive_authorization()</function> enables or disables
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interactive authorization for method calls. If true, messages are marked with the
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<constant>ALLOW_INTERACTIVE_AUTHORIZATION</constant> flag specified by the
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<ulink url="view-source:https://dbus.freedesktop.org/doc/dbus-specification.html">D-Bus</ulink>
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specification, informing the receiving side that the caller is prepared to wait for interactive
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authorization, which might take a considerable time to complete. If this flag is set, the user
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may be queried for passwords or confirmation via
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<ulink url="https://www.freedesktop.org/wiki/Software/polkit">polkit</ulink> or a similar
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framework.</para>
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<para><function>sd_bus_get_allow_interactive_authorization()</function> returns true if
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interactive authorization is allowed and false if not.</para>
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<para><function>sd_bus_get_scope()</function> stores the scope of the given bus object in
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<parameter>scope</parameter>. The scope of the system bus is <literal>system</literal>. The
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scope of a user session bus is <literal>user</literal>. If the given bus object is not the
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system or a user session bus, <function>sd_bus_get_scope()</function> returns an error.</para>
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<para><function>sd_bus_get_tid()</function> stores the kernel thread id of the thread associated
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with the given bus object in <parameter>tid</parameter>. If <parameter>bus</parameter> is a
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default bus object obtained by calling one of the functions of the
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<citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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family of functions, it stores the thread id of the thread the bus object was created in.
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Otherwise, if the bus object is attached to an event loop, it stores the thread id of the
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thread the event loop object was created in. If <parameter>bus</parameter> is not a default bus
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object and is not attached to an event loop, <function>sd_bus_get_tid()</function> returns an
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error.</para>
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<para><function>sd_bus_get_unique_name()</function> stores the unique name of the bus object on
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the bus in <parameter>unique</parameter>. See
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<ulink url="https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus">
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The D-Bus specification</ulink> for more information on bus names. Note that the caller does not
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own the string stored in <parameter>unique</parameter> and should not free it.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On success, these functions return a non-negative integer. On failure, they return a
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negative errno-style error code.</para>
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<refsect2>
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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><constant>-EINVAL</constant></term>
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<listitem><para>An argument is invalid.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOPKG</constant></term>
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<listitem><para>The bus cannot be resolved.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EPERM</constant></term>
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<listitem><para>The bus has already been started.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ECHILD</constant></term>
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<listitem><para>The bus was created in a different process, library or module instance.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOMEM</constant></term>
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<listitem><para>Memory allocation failed.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENODATA</constant></term>
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<listitem><para>The bus object passed to <function>sd_bus_get_scope()</function> was not a
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system or user session bus.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENXIO</constant></term>
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<listitem><para>The bus object passed to <function>sd_bus_get_tid()</function> was not a
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default bus object and is not attached to an event loop.</para>
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<para>The bus object passed to <function>sd_bus_get_description()</function> did
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not have a <parameter>description</parameter>.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect2>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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<refsect1>
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<title>See Also</title>
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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>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_open_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_open_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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