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systemd-stable/man/sd_pid_get_session.xml
Tom Gundersen 12b42c7667 man: revert dynamic paths for split-usr setups
This did not really work out as we had hoped. Trying to do this upstream
introduced several problems that probably makes it better suited as a
downstream patch after all. At any rate, it is not releaseable in the
current state, so we at least need to revert this before the release.

 * by adjusting the path to binaries, but not do the same thing to the
   search path we end up with inconsistent man-pages. Adjusting the search
   path too would be quite messy, and it is not at all obvious that this is
   worth the effort, but at any rate it would have to be done before we
   could ship this.

 * this means that distributed man-pages does not make sense as they depend
   on config options, and for better or worse we are still distributing
   man pages, so that is something that definitely needs sorting out before
   we could ship with this patch.

 * we have long held that split-usr is only minimally supported in order
   to boot, and something we hope will eventually go away. So before we start
   adding even more magic/effort in order to make this work nicely, we should
   probably question if it makes sense at all.
2015-06-18 19:47:44 +02:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!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 2010 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_pid_get_session" conditional='HAVE_PAM'>
<refentryinfo>
<title>sd_pid_get_session</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_pid_get_session</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_pid_get_session</refname>
<refname>sd_pid_get_unit</refname>
<refname>sd_pid_get_user_unit</refname>
<refname>sd_pid_get_owner_uid</refname>
<refname>sd_pid_get_machine_name</refname>
<refname>sd_pid_get_slice</refname>
<refname>sd_peer_get_session</refname>
<refname>sd_peer_get_unit</refname>
<refname>sd_peer_get_user_unit</refname>
<refname>sd_peer_get_owner_uid</refname>
<refname>sd_peer_get_machine_name</refname>
<refname>sd_peer_get_slice</refname>
<refpurpose>Determine session, service, owner of a
session, container/VM or slice of a specific
PID or socket peer</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_pid_get_session</function></funcdef>
<paramdef>pid_t <parameter>pid</parameter></paramdef>
<paramdef>char **<parameter>session</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_pid_get_unit</function></funcdef>
<paramdef>pid_t <parameter>pid</parameter></paramdef>
<paramdef>char **<parameter>unit</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_pid_get_user_unit</function></funcdef>
<paramdef>pid_t <parameter>pid</parameter></paramdef>
<paramdef>char **<parameter>unit</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
<paramdef>pid_t <parameter>pid</parameter></paramdef>
<paramdef>uid_t *<parameter>uid</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_pid_get_machine_name</function></funcdef>
<paramdef>pid_t <parameter>pid</parameter></paramdef>
<paramdef>char **<parameter>name</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_pid_get_slice</function></funcdef>
<paramdef>pid_t <parameter>pid</parameter></paramdef>
<paramdef>char **<parameter>slice</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_peer_get_session</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>char **<parameter>session</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_peer_get_unit</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>char **<parameter>unit</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_peer_get_user_unit</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>char **<parameter>unit</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_peer_get_owner_uid</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>uid_t *<parameter>uid</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_peer_get_machine_name</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>char **<parameter>name</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_peer_get_slice</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>char **<parameter>slice</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_pid_get_session()</function> may be used to
determine the login session identifier of a process identified by
the specified process identifier. The session identifier is a
short string, suitable for usage in file system paths. Note that
not all processes are part of a login session (e.g. system service
processes, user processes that are shared between multiple
sessions of the same user, or kernel threads). For processes not
being part of a login session this function will fail with
-ENXIO. The returned string needs to be freed with the libc
<citerefentry
project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call after use.</para>
<para><function>sd_pid_get_unit()</function> may be used to
determine the systemd system unit (i.e. system service) identifier
of a process identified by the specified PID. The unit name is a
short string, suitable for usage in file system paths. Note that
not all processes are part of a system unit/service (e.g. user
processes, or kernel threads). For processes not being part of a
systemd system unit this function will fail with -ENXIO (More
specifically: this call will not work for processes that are part
of user units, use <function>sd_pid_get_user_unit()</function> for
that.) The returned string needs to be freed with the libc
<citerefentry
project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call after use.</para>
<para><function>sd_pid_get_user_unit()</function> may be used to
determine the systemd user unit (i.e. user service) identifier of
a process identified by the specified PID. This is similar to
<function>sd_pid_get_unit()</function> but applies to user units
instead of system units.</para>
<para><function>sd_pid_get_owner_uid()</function> may be used to
determine the Unix user identifier of the owner of the session of
a process identified the specified PID. Note that this function
will succeed for user processes which are shared between multiple
login sessions of the same user, where
<function>sd_pid_get_session()</function> will fail. For processes
not being part of a login session and not being a shared process
of a user this function will fail with -ENXIO.</para>
<para><function>sd_pid_get_machine_name()</function> may be used
to determine the name of the VM or container is a member of. The
machine name is a short string, suitable for usage in file system
paths. The returned string needs to be freed with the libc
<citerefentry
project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call after use. For processes not part of a VM or containers this
function fails with -ENXIO.</para>
<para><function>sd_pid_get_slice()</function> may be used to
determine the slice unit the process is a member of. See
<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details about slices. The returned string needs to be freed
with the libc
<citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call after use.</para>
<para>If the <varname>pid</varname> parameter of any of these
functions is passed as 0, the operation is executed for the
calling process.</para>
<para>The <function>sd_peer_get_session()</function>,
<function>sd_peer_get_unit()</function>,
<function>sd_peer_get_user_unit()</function>,
<function>sd_peer_get_owner_uid()</function>,
<function>sd_peer_get_machine_name()</function> and
<function>sd_peer_get_slice()</function> calls operate similar to
their PID counterparts, but operate on a connected AF_UNIX socket
and retrieve information about the connected peer process.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, these calls return 0 or a positive integer. On
failure, these calls 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>-ENXIO</constant></term>
<listitem><para>Given field is not specified for the described
process or peer.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>-ESRCH</constant></term>
<listitem><para>The specified PID does not refer to a running
process.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The <function>sd_pid_get_session()</function>,
<function>sd_pid_get_unit()</function>,
<function>sd_pid_get_user_unit()</function>,
<function>sd_pid_get_owner_uid()</function>,
<function>sd_pid_get_machine_name()</function>,
<function>sd_pid_get_slice()</function>,
<function>sd_peer_get_session()</function>,
<function>sd_peer_get_unit()</function>,
<function>sd_peer_get_user_unit()</function>,
<function>sd_peer_get_owner_uid()</function>,
<function>sd_peer_get_machine_name()</function> and
<function>sd_peer_get_slice()</function> interfaces 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>
<para>Note that the login session identifier as
returned by <function>sd_pid_get_session()</function>
is completely unrelated to the process session
identifier as returned by
<citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>