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b1de39dec8
Logically, this is better, because we're describing a subset of possible return values. Visually this also looks quite good because groff renders refsect2 much less prominently. Also rewrap things, add <constant> in various places, fix some typos.
315 lines
13 KiB
XML
315 lines
13 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1+ -->
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<refentry id="sd_pid_get_owner_uid" conditional='HAVE_PAM'
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_pid_get_owner_uid</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_pid_get_owner_uid</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_pid_get_owner_uid</refname>
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<refname>sd_pid_get_session</refname>
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<refname>sd_pid_get_user_unit</refname>
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<refname>sd_pid_get_unit</refname>
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<refname>sd_pid_get_machine_name</refname>
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<refname>sd_pid_get_slice</refname>
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<refname>sd_pid_get_user_slice</refname>
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<refname>sd_pid_get_cgroup</refname>
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<refname>sd_peer_get_owner_uid</refname>
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<refname>sd_peer_get_session</refname>
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<refname>sd_peer_get_user_unit</refname>
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<refname>sd_peer_get_unit</refname>
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<refname>sd_peer_get_machine_name</refname>
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<refname>sd_peer_get_slice</refname>
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<refname>sd_peer_get_user_slice</refname>
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<refname>sd_peer_get_cgroup</refname>
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<refpurpose>Determine the owner uid of the user unit or session,
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or the session, user unit, system unit, container/VM or slice that
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a specific PID or socket peer belongs to.</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>uid_t *<parameter>uid</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_session</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>session</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_user_unit</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>unit</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_unit</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>unit</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_machine_name</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>name</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_slice</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>slice</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_user_slice</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>slice</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_cgroup</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>cgroup</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_owner_uid</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>uid_t *<parameter>uid</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_session</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>session</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_user_unit</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>unit</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_unit</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>unit</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_machine_name</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>name</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_slice</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>slice</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_user_slice</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>slice</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_cgroup</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>cgroup</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_pid_get_owner_uid()</function> may be used to
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determine the Unix UID (user identifier) which owns the login
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session or systemd user unit of a process identified by the
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specified PID. For processes which are not part of a login session
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and not managed by a user manager, this function will fail with
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<constant>-ENODATA</constant>.</para>
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<para><function>sd_pid_get_session()</function> may be used to
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determine the login session identifier of a process identified by
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the specified process identifier. The session identifier is a
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short string, suitable for usage in file system paths. Please
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note the login session may be limited to a stub process or two.
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User processes may instead be started from their systemd user
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manager, e.g. GUI applications started using DBus activation, as
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well as service processes which are shared between multiple logins
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of the same user. For processes which are not part of a login
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session, this function will fail with <constant>-ENODATA</constant>.
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The returned string needs to be freed with the libc <citerefentry
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project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use.</para>
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<para><function>sd_pid_get_user_unit()</function> may be used to
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determine the systemd user unit (i.e. user service or scope unit)
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identifier of a process identified by the specified PID. The
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unit name is a short string, suitable for usage in file system
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paths. For processes which are not managed by a user manager, this
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function will fail with <constant>-ENODATA</constant>. The
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returned string needs to be freed with the libc <citerefentry
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project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use.</para>
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<para><function>sd_pid_get_unit()</function> may be used to
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determine the systemd system unit (i.e. system service or scope
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unit) identifier of a process identified by the specified PID. The
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unit name is a short string, suitable for usage in file system
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paths. Note that not all processes are part of a system
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unit/service. For processes not being part of a systemd system
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unit, this function will fail with <constant>-ENODATA</constant>.
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(More specifically, this call will not work for kernel threads.)
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The returned string needs to be freed with the libc <citerefentry
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project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use.</para>
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<para><function>sd_pid_get_machine_name()</function> may be used
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to determine the name of the VM or container is a member of. The
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machine name is a short string, suitable for usage in file system
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paths. The returned string needs to be freed with the libc
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<citerefentry
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project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use. For processes not part of a VM or container, this
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function fails with <constant>-ENODATA</constant>.</para>
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<para><function>sd_pid_get_slice()</function> may be used to
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determine the slice unit the process is a member of. See
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<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details about slices. The returned string needs to be freed
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with the libc
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<citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use.</para>
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<para>Similarly, <function>sd_pid_get_user_slice()</function>
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returns the user slice (as managed by the user's systemd instance)
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of a process.</para>
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<para><function>sd_pid_get_cgroup()</function> returns the control
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group path of the specified process, relative to the root of the
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hierarchy. Returns the path without trailing slash, except for
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processes located in the root control group, where "/" is
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returned. To find the actual control group path in the file system,
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the returned path needs to be prefixed with
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<filename>/sys/fs/cgroup/</filename> (if the unified control group
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setup is used), or
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<filename>/sys/fs/cgroup/<replaceable>HIERARCHY</replaceable>/</filename>
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(if the legacy multi-hierarchy control group setup is used).</para>
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<para>If the <varname>pid</varname> parameter of any of these
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functions is passed as 0, the operation is executed for the
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calling process.</para>
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<para>The <function>sd_peer_get_owner_uid()</function>,
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<function>sd_peer_get_session()</function>,
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<function>sd_peer_get_user_unit()</function>,
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<function>sd_peer_get_unit()</function>,
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<function>sd_peer_get_machine_name()</function>,
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<function>sd_peer_get_slice()</function>,
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<function>sd_peer_get_user_slice()</function> and
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<function>sd_peer_get_cgroup()</function> calls operate similar to
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their PID counterparts, but operate on a connected AF_UNIX socket
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and retrieve information about the connected peer process. Note
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that these fields are retrieved via <filename>/proc</filename>,
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and hence are not suitable for authorization purposes, as they are
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subject to races.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On success, these calls return 0 or a positive integer. On failure, these calls return a negative
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errno-style error code.</para>
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<refsect2>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-ESRCH</constant></term>
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<listitem><para>The specified PID does not refer to a running process.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EBADF</constant></term>
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<listitem><para>The specified socket file descriptor was invalid.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENODATA</constant></term>
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<listitem><para>The given field is not specified for the described process or peer.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>An input parameter was invalid (out of range, or <constant>NULL</constant>, where
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that is not accepted).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOMEM</constant></term>
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<listitem><para>Memory allocation failed.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect2>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
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<para>Note that the login session identifier as
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returned by <function>sd_pid_get_session()</function>
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is completely unrelated to the process session
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identifier as returned by
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<citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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