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3802a3d3 | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
ce236b57 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
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6 | SPDX-License-Identifier: LGPL-2.1+ |
7 | ||
5de0ccff | 8 | This file is part of systemd. |
ce236b57 | 9 | |
5de0ccff | 10 | Copyright 2014 Lennart Poettering |
ce236b57 | 11 | |
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12 | systemd is free software; you can redistribute it and/or modify it |
13 | under the terms of the GNU Lesser General Public License as published by | |
14 | the Free Software Foundation; either version 2.1 of the License, or | |
15 | (at your option) any later version. | |
ce236b57 | 16 | |
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17 | systemd is distributed in the hope that it will be useful, but |
18 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
20 | Lesser General Public License for more details. | |
ce236b57 | 21 | |
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22 | You should have received a copy of the GNU Lesser General Public License |
23 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
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24 | --> |
25 | ||
48f69d8f | 26 | <refentry id="sd_bus_negotiate_fds"> |
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27 | |
28 | <refentryinfo> | |
faae655d | 29 | <title>sd_bus_negotiate_fds</title> |
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30 | <productname>systemd</productname> |
31 | ||
32 | <authorgroup> | |
33 | <author> | |
34 | <contrib>Developer</contrib> | |
35 | <firstname>Lennart</firstname> | |
36 | <surname>Poettering</surname> | |
37 | <email>lennart@poettering.net</email> | |
38 | </author> | |
39 | </authorgroup> | |
40 | </refentryinfo> | |
41 | ||
42 | <refmeta> | |
43 | <refentrytitle>sd_bus_negotiate_fds</refentrytitle> | |
44 | <manvolnum>3</manvolnum> | |
45 | </refmeta> | |
46 | ||
47 | <refnamediv> | |
48 | <refname>sd_bus_negotiate_fds</refname> | |
02855643 | 49 | <refname>sd_bus_negotiate_timestamp</refname> |
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50 | <refname>sd_bus_negotiate_creds</refname> |
51 | ||
52 | <refpurpose>Control feature negotiation on bus connections</refpurpose> | |
53 | </refnamediv> | |
54 | ||
55 | <refsynopsisdiv> | |
56 | <funcsynopsis> | |
57 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
58 | ||
59 | <funcprototype> | |
60 | <funcdef>int <function>sd_bus_negotiate_fds</function></funcdef> | |
61 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
62 | <paramdef>int <parameter>b</parameter></paramdef> | |
63 | </funcprototype> | |
64 | ||
65 | <funcprototype> | |
66 | <funcdef>int <function>sd_bus_negotiate_timestamp</function></funcdef> | |
67 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
68 | <paramdef>int <parameter>b</parameter></paramdef> | |
69 | </funcprototype> | |
70 | ||
71 | <funcprototype> | |
72 | <funcdef>int <function>sd_bus_negotiate_creds</function></funcdef> | |
73 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
74 | <paramdef>int <parameter>b</parameter></paramdef> | |
850df10a | 75 | <paramdef>uint64_t <parameter>mask</parameter></paramdef> |
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76 | </funcprototype> |
77 | </funcsynopsis> | |
78 | </refsynopsisdiv> | |
79 | ||
80 | <refsect1> | |
81 | <title>Description</title> | |
82 | ||
83 | <para><function>sd_bus_negotiate_fds()</function> controls whether | |
84 | file descriptor passing shall be negotiated for the specified bus | |
b8bde116 | 85 | connection. It takes a bus object and a boolean, which, when true, |
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86 | enables file descriptor passing, and, when false, disables |
87 | it. Note that not all transports and servers support file | |
88 | descriptor passing. In particular, networked transports generally | |
89 | do not support file descriptor passing. To find out whether file | |
90 | descriptor passing is available after negotiation, use | |
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91 | <citerefentry><refentrytitle>sd_bus_can_send</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
92 | and pass <constant>SD_BUS_TYPE_UNIX_FD</constant>. Note that file | |
93 | descriptor passing is always enabled for both sending and | |
94 | receiving or for neither, but never only in one direction. By | |
b8bde116 | 95 | default, file descriptor passing is negotiated for all |
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96 | connections.</para> |
97 | ||
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98 | <para><function>sd_bus_negotiate_timestamp()</function> controls whether implicit sender |
99 | timestamps shall be attached automatically to all incoming messages. Takes a bus object and a | |
100 | boolean, which, when true, enables timestamping, and, when false, disables it. Use | |
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101 | <citerefentry><refentrytitle>sd_bus_message_get_monotonic_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
102 | <citerefentry><refentrytitle>sd_bus_message_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
ae937639 | 103 | <citerefentry><refentrytitle>sd_bus_message_get_seqnum</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
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104 | to query the timestamps of incoming messages. If negotiation is disabled or not supported, these |
105 | calls will fail with <constant>-ENODATA</constant>. Note that currently no transports support | |
106 | timestamping of messages. By default, message timestamping is not negotiated for | |
850df10a | 107 | connections.</para> |
ce236b57 | 108 | |
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109 | <para><function>sd_bus_negotiate_creds()</function> controls whether and which implicit sender |
110 | credentials shall be attached automatically to all incoming messages. Takes a bus object and a | |
111 | boolean indicating whether to enable or disable the credential parts encoded in the bit mask | |
112 | value argument. Note that not all transports support attaching sender credentials to messages, | |
113 | or do not support all types of sender credential parameters, or might suppress them under | |
114 | certain circumstances for individual messages. Specifically, dbus1 only supports | |
115 | <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>. The sender credentials are suitable for | |
116 | authorization decisions. By default, only <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant> and | |
117 | <constant>SD_BUS_CREDS_UNIQUE_NAME</constant> are enabled. In fact, these two credential fields | |
118 | are always sent along and cannot be turned off.</para> | |
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119 | |
120 | <para>The <function>sd_bus_negotiate_fds()</function> function may | |
121 | be called only before the connection has been started with | |
122 | <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Both | |
123 | <function>sd_bus_negotiate_timestamp()</function> and | |
850df10a | 124 | <function>sd_bus_negotiate_creds()</function> may also be called |
b938cb90 | 125 | after a connection has been set up. Note that, when operating on a |
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126 | connection that is shared between multiple components of the same |
127 | program (for example via | |
a8eaaee7 | 128 | <citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry>), |
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129 | it is highly recommended to only enable additional per message |
130 | metadata fields, but never disable them again, in order not to | |
131 | disable functionality needed by other components.</para> | |
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132 | </refsect1> |
133 | ||
134 | <refsect1> | |
135 | <title>Return Value</title> | |
136 | ||
dd2b607b | 137 | <para>On success, these functions return 0 or a |
faae655d | 138 | positive integer. On failure, they return a negative errno-style |
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139 | error code.</para> |
140 | </refsect1> | |
141 | ||
142 | <refsect1> | |
143 | <title>Errors</title> | |
144 | ||
145 | <para>Returned errors may indicate the following problems:</para> | |
146 | ||
147 | <variablelist> | |
148 | <varlistentry> | |
8474b70c | 149 | <term><constant>-EPERM</constant></term> |
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150 | |
151 | <listitem><para>The bus connection has already been started.</para></listitem> | |
152 | </varlistentry> | |
153 | </variablelist> | |
154 | </refsect1> | |
155 | ||
156 | <refsect1> | |
157 | <title>Notes</title> | |
158 | ||
850df10a | 159 | <para><function>sd_bus_negotiate_fds()</function> and the other |
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160 | functions described here are available as a shared library, which |
161 | can be compiled and linked to with the | |
5aded369 | 162 | <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
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163 | file.</para> |
164 | </refsect1> | |
165 | ||
166 | <refsect1> | |
167 | <title>See Also</title> | |
168 | ||
169 | <para> | |
170 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
171 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
172 | <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
173 | <citerefentry><refentrytitle>sd_bus_message_can_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
174 | <citerefentry><refentrytitle>sd_bus_message_get_monotonic_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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175 | <citerefentry><refentrytitle>sd_bus_message_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
176 | <citerefentry><refentrytitle>sd_bus_message_get_seqnum</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
4bc5d27b | 177 | <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
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178 | </para> |
179 | </refsect1> | |
180 | ||
181 | </refentry> |