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sd-login: add calls that retrieve credentials of peers connected to AF_UNIX peers
[elogind.git] / man / sd_pid_get_session.xml
1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4
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8   Copyright 2010 Lennart Poettering
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23
24 <refentry id="sd_pid_get_session" conditional='HAVE_PAM'>
25
26         <refentryinfo>
27                 <title>sd_pid_get_session</title>
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_pid_get_session</refentrytitle>
42                 <manvolnum>3</manvolnum>
43         </refmeta>
44
45         <refnamediv>
46                 <refname>sd_pid_get_session</refname>
47                 <refname>sd_pid_get_unit</refname>
48                 <refname>sd_pid_get_user_unit</refname>
49                 <refname>sd_pid_get_owner_uid</refname>
50                 <refname>sd_pid_get_machine_name</refname>
51                 <refname>sd_pid_get_slice</refname>
52                 <refname>sd_peer_get_session</refname>
53                 <refname>sd_peer_get_unit</refname>
54                 <refname>sd_peer_get_user_unit</refname>
55                 <refname>sd_peer_get_owner_uid</refname>
56                 <refname>sd_peer_get_machine_name</refname>
57                 <refname>sd_peer_get_slice</refname>
58                 <refpurpose>Determine session, service, owner of a
59                 session, container/VM or slice of a specific
60                 PID or socket peer</refpurpose>
61         </refnamediv>
62
63         <refsynopsisdiv>
64                 <funcsynopsis>
65                         <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
66
67                         <funcprototype>
68                                 <funcdef>int <function>sd_pid_get_session</function></funcdef>
69                                 <paramdef>pid_t <parameter>pid</parameter></paramdef>
70                                 <paramdef>char** <parameter>session</parameter></paramdef>
71                         </funcprototype>
72
73                         <funcprototype>
74                                 <funcdef>int <function>sd_pid_get_unit</function></funcdef>
75                                 <paramdef>pid_t <parameter>pid</parameter></paramdef>
76                                 <paramdef>char** <parameter>unit</parameter></paramdef>
77                         </funcprototype>
78
79                         <funcprototype>
80                                 <funcdef>int <function>sd_pid_get_user_unit</function></funcdef>
81                                 <paramdef>pid_t <parameter>pid</parameter></paramdef>
82                                 <paramdef>char** <parameter>unit</parameter></paramdef>
83                         </funcprototype>
84
85                         <funcprototype>
86                                 <funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
87                                 <paramdef>pid_t <parameter>pid</parameter></paramdef>
88                                 <paramdef>uid_t* <parameter>uid</parameter></paramdef>
89                         </funcprototype>
90
91                         <funcprototype>
92                                 <funcdef>int <function>sd_pid_get_machine_name</function></funcdef>
93                                 <paramdef>pid_t <parameter>pid</parameter></paramdef>
94                                 <paramdef>char** <parameter>name</parameter></paramdef>
95                         </funcprototype>
96
97                         <funcprototype>
98                                 <funcdef>int <function>sd_pid_get_slice</function></funcdef>
99                                 <paramdef>pid_t <parameter>pid</parameter></paramdef>
100                                 <paramdef>char** <parameter>slice</parameter></paramdef>
101                         </funcprototype>
102
103                         <funcprototype>
104                                 <funcdef>int <function>sd_peer_get_session</function></funcdef>
105                                 <paramdef>int <parameter>fd</parameter></paramdef>
106                                 <paramdef>char** <parameter>session</parameter></paramdef>
107                         </funcprototype>
108
109                         <funcprototype>
110                                 <funcdef>int <function>sd_peer_get_unit</function></funcdef>
111                                 <paramdef>int <parameter>fd</parameter></paramdef>
112                                 <paramdef>char** <parameter>unit</parameter></paramdef>
113                         </funcprototype>
114
115                         <funcprototype>
116                                 <funcdef>int <function>sd_peer_get_user_unit</function></funcdef>
117                                 <paramdef>int <parameter>fd</parameter></paramdef>
118                                 <paramdef>char** <parameter>unit</parameter></paramdef>
119                         </funcprototype>
120
121                         <funcprototype>
122                                 <funcdef>int <function>sd_peer_get_owner_uid</function></funcdef>
123                                 <paramdef>int <parameter>fd</parameter></paramdef>
124                                 <paramdef>uid_t* <parameter>uid</parameter></paramdef>
125                         </funcprototype>
126
127                         <funcprototype>
128                                 <funcdef>int <function>sd_peer_get_machine_name</function></funcdef>
129                                 <paramdef>int <parameter>fd</parameter></paramdef>
130                                 <paramdef>char** <parameter>name</parameter></paramdef>
131                         </funcprototype>
132
133                         <funcprototype>
134                                 <funcdef>int <function>sd_peer_get_slice</function></funcdef>
135                                 <paramdef>int <parameter>fd</parameter></paramdef>
136                                 <paramdef>char** <parameter>slice</parameter></paramdef>
137                         </funcprototype>
138                 </funcsynopsis>
139         </refsynopsisdiv>
140
141         <refsect1>
142                 <title>Description</title>
143
144                 <para><function>sd_pid_get_session()</function> may be
145                 used to determine the login session identifier of a
146                 process identified by the specified process
147                 identifier. The session identifier is a short string,
148                 suitable for usage in file system paths. Note that not
149                 all processes are part of a login session (e.g. system
150                 service processes, user processes that are shared
151                 between multiple sessions of the same user, or kernel
152                 threads). For processes not being part of a login
153                 session this function will fail. The returned string
154                 needs to be freed with the libc
155                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
156                 call after use.</para>
157
158                 <para><function>sd_pid_get_unit()</function> may be
159                 used to determine the systemd system unit (i.e. system
160                 service) identifier of a process identified by the
161                 specified PID. The unit name is a short string,
162                 suitable for usage in file system paths. Note that not
163                 all processes are part of a system unit/service
164                 (e.g. user processes, or kernel threads). For
165                 processes not being part of a systemd system unit this
166                 function will fail. (More specifically: this call will
167                 not work for processes that are part of user units,
168                 use <function>sd_pid_get_user_unit()</function> for
169                 that.) The returned string needs to be freed with the
170                 libc
171                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
172                 call after use.</para>
173
174                 <para><function>sd_pid_get_user_unit()</function> may
175                 be used to determine the systemd user unit (i.e. user
176                 service) identifier of a process identified by the
177                 specified PID. This is similar to
178                 <function>sd_pid_get_unit()</function> but applies to
179                 user units instead of system units.</para>
180
181                 <para><function>sd_pid_get_owner_uid()</function> may
182                 be used to determine the Unix user identifier of the
183                 owner of the session of a process identified the
184                 specified PID. Note that this function will succeed
185                 for user processes which are shared between multiple
186                 login sessions of the same user, where
187                 <function>sd_pid_get_session()</function> will
188                 fail. For processes not being part of a login session
189                 and not being a shared process of a user this function
190                 will fail.</para>
191
192                 <para><function>sd_pid_get_machine_name()</function>
193                 may be used to determine the name of the VM or
194                 container is a member of. The machine name is a short
195                 string, suitable for usage in file system paths. The
196                 returned string needs to be freed with the libc
197                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
198                 call after use.</para>
199
200                 <para><function>sd_pid_get_slice()</function> may be
201                 used to determine the slice unit the process is a
202                 member of. See
203                 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
204                 for details about slices. The returned string needs to
205                 be freed with the libc
206                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
207                 call after use.</para>
208
209                 <para>If the <varname>pid</varname> parameter of any
210                 of these functions is passed as 0, the operation is
211                 executed for the calling process.</para>
212
213                 <para>The <function>sd_peer_get_session()</function>,
214                 <function>sd_peer_get_unit()</function>,
215                 <function>sd_peer_get_user_unit()</function>,
216                 <function>sd_peer_get_owner_uid()</function>,
217                 <function>sd_peer_get_machine_name()</function> and
218                 <function>sd_peer_get_slice()</function> calls operate
219                 similar to their PID counterparts, but operate on a
220                 connected AF_UNIX socket and retrieve information
221                 about the connected peer process.</para>
222         </refsect1>
223
224         <refsect1>
225                 <title>Return Value</title>
226
227                 <para>On success, these calls return 0 or a positive
228                 integer. On failure, these calls return a negative
229                 errno-style error code.</para>
230         </refsect1>
231
232         <refsect1>
233                 <title>Notes</title>
234
235                 <para>The <function>sd_pid_get_session()</function>,
236                 <function>sd_pid_get_unit()</function>,
237                 <function>sd_pid_get_user_unit()</function>,
238                 <function>sd_pid_get_owner_uid()</function>,
239                 <function>sd_pid_get_machine_name()</function>,
240                 <function>sd_pid_get_slice()</function>,
241                 <function>sd_peer_get_session()</function>,
242                 <function>sd_peer_get_unit()</function>,
243                 <function>sd_peer_get_user_unit()</function>,
244                 <function>sd_peer_get_owner_uid()</function>,
245                 <function>sd_peer_get_machine_name()</function> and
246                 <function>sd_peer_get_slice()</function> interfaces are
247                 available as a shared library, which can be compiled
248                 and linked to with the
249                 <constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
250                 file.</para>
251
252                 <para>Note that the login session identifier as
253                 returned by <function>sd_pid_get_session()</function>
254                 is completely unrelated to the process session
255                 identifier as returned by
256                 <citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>.</para>
257         </refsect1>
258
259         <refsect1>
260                 <title>See Also</title>
261
262                 <para>
263                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
264                         <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
265                         <citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
266                         <citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
267                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
268                 </para>
269         </refsect1>
270
271 </refentry>