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+<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
+<!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 Lennart Poettering
+
+ 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_negotiate_fds">
+
+ <refentryinfo>
+ <title>sd_bus_negotiate_fds</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Lennart</firstname>
+ <surname>Poettering</surname>
+ <email>lennart@poettering.net</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>sd_bus_negotiate_fds</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd_bus_negotiate_fds</refname>
+ <refname>sd_bus_negotiate_timestamp</refname>
+ <refname>sd_bus_negotiate_creds</refname>
+
+ <refpurpose>Control feature negotiation on bus connections</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
+
+ <funcprototype>
+ <funcdef>int <function>sd_bus_negotiate_fds</function></funcdef>
+ <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
+ <paramdef>int <parameter>b</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_bus_negotiate_timestamp</function></funcdef>
+ <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
+ <paramdef>int <parameter>b</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_bus_negotiate_creds</function></funcdef>
+ <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
+ <paramdef>int <parameter>b</parameter></paramdef>
+ <paramdef>uint64_t <parameter>mask</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><function>sd_bus_negotiate_fds()</function> controls whether
+ file descriptor passing shall be negotiated for the specified bus
+ connection. It takes a bus object and a boolean, which, when true,
+ enables file descriptor passing, and, when false, disables
+ it. Note that not all transports and servers support file
+ descriptor passing. In particular, networked transports generally
+ do not support file descriptor passing. To find out whether file
+ descriptor passing is available after negotiation, use
+ <citerefentry><refentrytitle>sd_bus_can_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ and pass <constant>SD_BUS_TYPE_UNIX_FD</constant>. Note that file
+ descriptor passing is always enabled for both sending and
+ receiving or for neither, but never only in one direction. By
+ default, file descriptor passing is negotiated for all
+ connections.</para>
+
+ <para>Note that when bus activation is used, it is highly
+ recommended to set the <option>AcceptFileDescriptors=</option>
+ setting in the <filename>.busname</filename> unit file to the same
+ setting as negotiated by the program ultimately activated. By
+ default, file descriptor passing is enabled for both.</para>
+
+ <para><function>sd_bus_negotiate_timestamp()</function> controls whether implicit sender
+ timestamps shall be attached automatically to all incoming messages. Takes a bus object and a
+ boolean, which, when true, enables timestamping, and, when false, disables it. Use
+ <citerefentry><refentrytitle>sd_bus_message_get_monotonic_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_message_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_message_get_seqnum</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ to query the timestamps of incoming messages. If negotiation is disabled or not supported, these
+ calls will fail with <constant>-ENODATA</constant>. Note that currently no transports support
+ timestamping of messages. By default, message timestamping is not negotiated for
+ connections.</para>
+
+ <para><function>sd_bus_negotiate_creds()</function> controls whether and which implicit sender
+ credentials shall be attached automatically to all incoming messages. Takes a bus object and a
+ boolean indicating whether to enable or disable the credential parts encoded in the bit mask
+ value argument. Note that not all transports support attaching sender credentials to messages,
+ or do not support all types of sender credential parameters, or might suppress them under
+ certain circumstances for individual messages. Specifically, dbus1 only supports
+ <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>. The sender credentials are suitable for
+ authorization decisions. By default, only <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant> and
+ <constant>SD_BUS_CREDS_UNIQUE_NAME</constant> are enabled. In fact, these two credential fields
+ are always sent along and cannot be turned off.</para>
+
+ <para>The <function>sd_bus_negotiate_fds()</function> function may
+ be called only before the connection has been started with
+ <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Both
+ <function>sd_bus_negotiate_timestamp()</function> and
+ <function>sd_bus_negotiate_creds()</function> may also be called
+ after a connection has been set up. Note that, when operating on a
+ connection that is shared between multiple components of the same
+ program (for example via
+ <citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry>),
+ it is highly recommended to only enable additional per message
+ metadata fields, but never disable them again, in order not to
+ disable functionality needed by other components.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Return Value</title>
+
+ <para>On success, these functions return 0 or a
+ positive integer. On failure, they return a negative errno-style
+ error code.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Errors</title>
+
+ <para>Returned errors may indicate the following problems:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><constant>-EPERM</constant></term>
+
+ <listitem><para>The bus connection has already been started.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Notes</title>
+
+ <para><function>sd_bus_negotiate_fds()</function> and the other
+ functions described here are available as a shared library, which
+ can be compiled and linked to with the
+ <constant>libsystemd</constant> <citerefentry project='die-net'><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>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_message_can_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_message_get_monotonic_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_message_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_message_get_seqnum</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.busname</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>