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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 | <!-- | |
5de0ccff | 6 | This file is part of systemd. |
ce236b57 | 7 | |
5de0ccff | 8 | Copyright 2014 Lennart Poettering |
ce236b57 | 9 | |
5de0ccff ZJS |
10 | systemd is free software; you can redistribute it and/or modify it |
11 | under the terms of the GNU Lesser General Public License as published by | |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
13 | (at your option) any later version. | |
ce236b57 | 14 | |
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15 | systemd is distributed in the hope that it will be useful, but |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | Lesser General Public License for more details. | |
ce236b57 | 19 | |
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20 | You should have received a copy of the GNU Lesser General Public License |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
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22 | --> |
23 | ||
48f69d8f | 24 | <refentry id="sd_bus_negotiate_fds"> |
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25 | |
26 | <refentryinfo> | |
faae655d | 27 | <title>sd_bus_negotiate_fds</title> |
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28 | <productname>systemd</productname> |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>sd_bus_negotiate_fds</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_bus_negotiate_fds</refname> | |
02855643 | 47 | <refname>sd_bus_negotiate_timestamp</refname> |
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48 | <refname>sd_bus_negotiate_creds</refname> |
49 | ||
50 | <refpurpose>Control feature negotiation on bus connections</refpurpose> | |
51 | </refnamediv> | |
52 | ||
53 | <refsynopsisdiv> | |
54 | <funcsynopsis> | |
55 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
56 | ||
57 | <funcprototype> | |
58 | <funcdef>int <function>sd_bus_negotiate_fds</function></funcdef> | |
59 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
60 | <paramdef>int <parameter>b</parameter></paramdef> | |
61 | </funcprototype> | |
62 | ||
63 | <funcprototype> | |
64 | <funcdef>int <function>sd_bus_negotiate_timestamp</function></funcdef> | |
65 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
66 | <paramdef>int <parameter>b</parameter></paramdef> | |
67 | </funcprototype> | |
68 | ||
69 | <funcprototype> | |
70 | <funcdef>int <function>sd_bus_negotiate_creds</function></funcdef> | |
71 | <paramdef>sd_bus *<parameter>bus</parameter></paramdef> | |
72 | <paramdef>int <parameter>b</parameter></paramdef> | |
850df10a | 73 | <paramdef>uint64_t <parameter>mask</parameter></paramdef> |
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74 | </funcprototype> |
75 | </funcsynopsis> | |
76 | </refsynopsisdiv> | |
77 | ||
78 | <refsect1> | |
79 | <title>Description</title> | |
80 | ||
81 | <para><function>sd_bus_negotiate_fds()</function> controls whether | |
82 | file descriptor passing shall be negotiated for the specified bus | |
b8bde116 | 83 | connection. It takes a bus object and a boolean, which, when true, |
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84 | enables file descriptor passing, and, when false, disables |
85 | it. Note that not all transports and servers support file | |
86 | descriptor passing. In particular, networked transports generally | |
87 | do not support file descriptor passing. To find out whether file | |
88 | descriptor passing is available after negotiation, use | |
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89 | <citerefentry><refentrytitle>sd_bus_can_send</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
90 | and pass <constant>SD_BUS_TYPE_UNIX_FD</constant>. Note that file | |
91 | descriptor passing is always enabled for both sending and | |
92 | receiving or for neither, but never only in one direction. By | |
b8bde116 | 93 | default, file descriptor passing is negotiated for all |
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94 | connections.</para> |
95 | ||
b8bde116 | 96 | <para>Note that when bus activation is used, it is highly |
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97 | recommended to set the <option>AcceptFileDescriptors=</option> |
98 | setting in the <filename>.busname</filename> unit file to the same | |
99 | setting as negotiated by the program ultimately activated. By | |
b8bde116 | 100 | default, file descriptor passing is enabled for both.</para> |
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101 | |
102 | <para><function>sd_bus_negotiate_timestamps()</function> controls | |
103 | whether implicit sender timestamps shall be attached automatically | |
b8bde116 | 104 | to all incoming messages. Takes a bus object and a boolean, which, |
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105 | when true, enables timestamping, and, when false, disables it. |
106 | Use | |
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107 | <citerefentry><refentrytitle>sd_bus_message_get_monotonic_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
108 | <citerefentry><refentrytitle>sd_bus_message_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
ae937639 | 109 | <citerefentry><refentrytitle>sd_bus_message_get_seqnum</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
850df10a | 110 | to query the timestamps of incoming messages. If negotiation is |
b938cb90 | 111 | disabled or not supported, these calls will fail with |
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112 | <constant>-ENODATA</constant>. Note that not all transports |
113 | support timestamping of messages. Specifically, timestamping is | |
114 | only available on the kdbus transport, but not on dbus1. The | |
115 | timestamping is applied by the kernel and cannot be manipulated by | |
116 | userspace. By default, message timestamping is not negotiated for | |
117 | connections.</para> | |
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118 | |
119 | <para><function>sd_bus_negotiate_creds()</function> controls | |
850df10a | 120 | whether and which implicit sender credentials shall be attached |
a8eaaee7 | 121 | automatically to all incoming messages. Takes a bus object and a |
f131770b | 122 | boolean indicating whether to enable or disable the credential |
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123 | parts encoded in the bit mask value argument. Note that not all |
124 | transports support attaching sender credentials to messages, or do | |
125 | not support all types of sender credential parameters, or might | |
126 | suppress them under certain circumstances for individual | |
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127 | messages. Specifically, implicit sender credentials on messages |
128 | are only fully supported on kdbus transports, and dbus1 only | |
129 | supports <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>. The sender | |
130 | credentials are attached by the kernel and cannot be manipulated | |
131 | by userspace, and are thus suitable for authorization | |
132 | decisions. By default, only | |
133 | <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant> and | |
134 | <constant>SD_BUS_CREDS_UNIQUE_NAME</constant> are enabled. In | |
135 | fact, these two credential fields are always sent along and cannot | |
136 | be turned off.</para> | |
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137 | |
138 | <para>The <function>sd_bus_negotiate_fds()</function> function may | |
139 | be called only before the connection has been started with | |
140 | <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Both | |
141 | <function>sd_bus_negotiate_timestamp()</function> and | |
850df10a | 142 | <function>sd_bus_negotiate_creds()</function> may also be called |
b938cb90 | 143 | after a connection has been set up. Note that, when operating on a |
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144 | connection that is shared between multiple components of the same |
145 | program (for example via | |
a8eaaee7 | 146 | <citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry>), |
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147 | it is highly recommended to only enable additional per message |
148 | metadata fields, but never disable them again, in order not to | |
149 | disable functionality needed by other components.</para> | |
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150 | </refsect1> |
151 | ||
152 | <refsect1> | |
153 | <title>Return Value</title> | |
154 | ||
dd2b607b | 155 | <para>On success, these functions return 0 or a |
faae655d | 156 | positive integer. On failure, they return a negative errno-style |
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157 | error code.</para> |
158 | </refsect1> | |
159 | ||
160 | <refsect1> | |
161 | <title>Errors</title> | |
162 | ||
163 | <para>Returned errors may indicate the following problems:</para> | |
164 | ||
165 | <variablelist> | |
166 | <varlistentry> | |
8474b70c | 167 | <term><constant>-EPERM</constant></term> |
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168 | |
169 | <listitem><para>The bus connection has already been started.</para></listitem> | |
170 | </varlistentry> | |
171 | </variablelist> | |
172 | </refsect1> | |
173 | ||
174 | <refsect1> | |
175 | <title>Notes</title> | |
176 | ||
850df10a | 177 | <para><function>sd_bus_negotiate_fds()</function> and the other |
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178 | functions described here are available as a shared library, which |
179 | can be compiled and linked to with the | |
5aded369 | 180 | <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
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181 | file.</para> |
182 | </refsect1> | |
183 | ||
184 | <refsect1> | |
185 | <title>See Also</title> | |
186 | ||
187 | <para> | |
188 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
189 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
190 | <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
191 | <citerefentry><refentrytitle>sd_bus_message_can_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
192 | <citerefentry><refentrytitle>sd_bus_message_get_monotonic_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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193 | <citerefentry><refentrytitle>sd_bus_message_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
194 | <citerefentry><refentrytitle>sd_bus_message_get_seqnum</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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195 | <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
196 | <citerefentry><refentrytitle>systemd.busname</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
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197 | </para> |
198 | </refsect1> | |
199 | ||
200 | </refentry> |