man/sd_bus_creds_new_from_pid.xml - systemd-stable - Rivoreo Source Code Repositories

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 <refentry id="sd_bus_creds_new_from_pid">

   <refentryinfo>
     <title>sd_bus_creds_new_from_pid</title>
     <productname>systemd</productname>

     <authorgroup>
       <author>
         <contrib>A monkey with a typewriter</contrib>
         <firstname>Zbigniew</firstname>
         <surname>Jędrzejewski-Szmek</surname>
         <email>zbyszek@in.waw.pl</email>
       </author>
     </authorgroup>
   </refentryinfo>

   <refmeta>
     <refentrytitle>sd_bus_creds_new_from_pid</refentrytitle>
     <manvolnum>3</manvolnum>
   </refmeta>

   <refnamediv>
     <refname>sd_bus_creds_new_from_pid</refname>
     <refname>sd_bus_creds_get_mask</refname>
     <refname>sd_bus_creds_get_augmented_mask</refname>
     <refname>sd_bus_creds_ref</refname>
     <refname>sd_bus_creds_unref</refname>
     <refname>sd_bus_creds_unrefp</refname>

     <refpurpose>Retrieve credentials object for the specified PID</refpurpose>
   </refnamediv>

   <refsynopsisdiv>
     <funcsynopsis>
       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>

       <funcprototype>
         <funcdef>int <function>sd_bus_creds_new_from_pid</function></funcdef>
         <paramdef>pid_t <parameter>pid</parameter></paramdef>
         <paramdef>uint64_t <parameter>creds_mask</parameter></paramdef>
         <paramdef>sd_bus_creds **<parameter>ret</parameter></paramdef>
       </funcprototype>

       <funcprototype>
         <funcdef>uint64_t <function>sd_bus_creds_get_mask</function></funcdef>
         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
       </funcprototype>

       <funcprototype>
         <funcdef>uint64_t <function>sd_bus_creds_get_augmented_mask</function></funcdef>
         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
       </funcprototype>

       <funcprototype>
         <funcdef>sd_bus_creds *<function>sd_bus_creds_ref</function></funcdef>
         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
       </funcprototype>

       <funcprototype>
         <funcdef>sd_bus_creds *<function>sd_bus_creds_unref</function></funcdef>
         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
       </funcprototype>

       <funcprototype>
         <funcdef>void <function>sd_bus_creds_unrefp</function></funcdef>
         <paramdef>sd_bus_creds **<parameter>c</parameter></paramdef>
       </funcprototype>
     </funcsynopsis>

     <para>
       <constant>SD_BUS_CREDS_PID</constant>,
       <constant>SD_BUS_CREDS_PPID</constant>,
       <constant>SD_BUS_CREDS_TID</constant>,
       <constant>SD_BUS_CREDS_UID</constant>,
       <constant>SD_BUS_CREDS_EUID</constant>,
       <constant>SD_BUS_CREDS_SUID</constant>,
       <constant>SD_BUS_CREDS_FSUID</constant>,
       <constant>SD_BUS_CREDS_GID</constant>,
       <constant>SD_BUS_CREDS_EGID</constant>,
       <constant>SD_BUS_CREDS_SGID</constant>,
       <constant>SD_BUS_CREDS_FSGID</constant>,
       <constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>,
       <constant>SD_BUS_CREDS_COMM</constant>,
       <constant>SD_BUS_CREDS_TID_COMM</constant>,
       <constant>SD_BUS_CREDS_EXE</constant>,
       <constant>SD_BUS_CREDS_CMDLINE</constant>,
       <constant>SD_BUS_CREDS_CGROUP</constant>,
       <constant>SD_BUS_CREDS_UNIT</constant>,
       <constant>SD_BUS_CREDS_SLICE</constant>,
       <constant>SD_BUS_CREDS_USER_UNIT</constant>,
       <constant>SD_BUS_CREDS_USER_SLICE</constant>,
       <constant>SD_BUS_CREDS_SESSION</constant>,
       <constant>SD_BUS_CREDS_OWNER_UID</constant>,
       <constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>,
       <constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
       <constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>,
       <constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
       <constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>,
       <constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
       <constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>,
       <constant>SD_BUS_CREDS_TTY</constant>,
       <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>,
       <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>,
       <constant>SD_BUS_CREDS_DESCRIPTION</constant>,
       <constant>SD_BUS_CREDS_AUGMENT</constant>,
       <constant>_SD_BUS_CREDS_ALL</constant>
     </para>
   </refsynopsisdiv>

   <refsect1>
     <title>Description</title>

     <para><function>sd_bus_creds_new_from_pid()</function> creates a
     new credentials object and fills it with information about the
     process <parameter>pid</parameter>. The pointer to this object
     will be stored in the <parameter>ret</parameter> pointer. Note that
     credential objects may also be created and retrieved via
     <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
     <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
     and
     <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>

     <para>The information that will be stored is determined by
     <parameter>creds_mask</parameter>. It may contain a subset of ORed
     constants <constant>SD_BUS_CREDS_PID</constant>,
     <constant>SD_BUS_CREDS_PPID</constant>,
     <constant>SD_BUS_CREDS_TID</constant>,
     <constant>SD_BUS_CREDS_UID</constant>,
     <constant>SD_BUS_CREDS_EUID</constant>,
     <constant>SD_BUS_CREDS_SUID</constant>,
     <constant>SD_BUS_CREDS_FSUID</constant>,
     <constant>SD_BUS_CREDS_GID</constant>,
     <constant>SD_BUS_CREDS_EGID</constant>,
     <constant>SD_BUS_CREDS_SGID</constant>,
     <constant>SD_BUS_CREDS_FSGID</constant>,
     <constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>,
     <constant>SD_BUS_CREDS_COMM</constant>,
     <constant>SD_BUS_CREDS_TID_COMM</constant>,
     <constant>SD_BUS_CREDS_EXE</constant>,
     <constant>SD_BUS_CREDS_CMDLINE</constant>,
     <constant>SD_BUS_CREDS_CGROUP</constant>,
     <constant>SD_BUS_CREDS_UNIT</constant>,
     <constant>SD_BUS_CREDS_SLICE</constant>,
     <constant>SD_BUS_CREDS_USER_UNIT</constant>,
     <constant>SD_BUS_CREDS_USER_SLICE</constant>,
     <constant>SD_BUS_CREDS_SESSION</constant>,
     <constant>SD_BUS_CREDS_OWNER_UID</constant>,
     <constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>,
     <constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
     <constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>,
     <constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
     <constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>,
     <constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
     <constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>,
     <constant>SD_BUS_CREDS_TTY</constant>,
     <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>,
     <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>, and
     <constant>SD_BUS_CREDS_DESCRIPTION</constant>. Use the special
     value <constant>_SD_BUS_CREDS_ALL</constant> to request all
     supported fields. The <constant>SD_BUS_CREDS_AUGMENT</constant>
     constant may not be ORed into the mask for invocations of
     <function>sd_bus_creds_new_from_pid()</function>.</para>

     <para>Fields can be retrieved from the credentials object using
     <citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
     and other functions which correspond directly to the constants
     listed above.</para>

     <para>A mask of fields which were actually successfully retrieved
     can be retrieved with
     <function>sd_bus_creds_get_mask()</function>. If the credentials
     object was created with
     <function>sd_bus_creds_new_from_pid()</function>, this will be a
     subset of fields requested in <parameter>creds_mask</parameter>.
     </para>

     <para>Similar to <function>sd_bus_creds_get_mask()</function>, the
     function <function>sd_bus_creds_get_augmented_mask()</function>
     returns a bitmask of field constants. The mask indicates which
     credential fields have been retrieved in a non-atomic fashion. For
     credential objects created via
     <function>sd_bus_creds_new_from_pid()</function>, this mask will be
     identical to the mask returned by
     <function>sd_bus_creds_get_mask()</function>. However, for
     credential objects retrieved via
     <function>sd_bus_get_name_creds()</function>, this mask will be set
     for the credential fields that could not be determined atomically
     at peer connection time, and which were later added by reading
     augmenting credential data from
     <filename>/proc</filename>. Similarly, for credential objects
     retrieved via <function>sd_bus_get_owner_creds()</function>, the
     mask is set for the fields that could not be determined atomically
     at bus creation time, but have been augmented. Similarly, for
     credential objects retrieved via
     <function>sd_bus_message_get_creds()</function>, the mask is set
     for the fields that could not be determined atomically at message
     sending time, but have been augmented. The mask returned by
     <function>sd_bus_creds_get_augmented_mask()</function> is always a
     subset of (or identical to) the mask returned by
     <function>sd_bus_creds_get_mask()</function> for the same
     object. The latter call hence returns all credential fields
     available in the credential object, the former then marks the
     subset of those that have been augmented. Note that augmented
     fields are unsuitable for authorization decisions, as they may be
     retrieved at different times, thus being subject to races. Hence,
     augmented fields should be used exclusively for informational
     purposes.
     </para>

     <para><function>sd_bus_creds_ref()</function> creates a new
     reference to the credentials object <parameter>c</parameter>. This
     object will not be destroyed until
     <function>sd_bus_creds_unref()</function> has been called as many
     times plus once more. Once the reference count has dropped to zero,
     <parameter>c</parameter> cannot be used anymore, so further
     calls to <function>sd_bus_creds_ref(c)</function> or
     <function>sd_bus_creds_unref(c)</function> are illegal.</para>

     <para><function>sd_bus_creds_unref()</function> destroys a reference
     to <parameter>c</parameter>.</para>

     <para><function>sd_bus_creds_unrefp()</function> is similar to
     <function>sd_bus_creds_unref()</function> but takes a pointer to a
     pointer to an <type>sd_bus_creds</type> object. This call is useful in
     conjunction with GCC's and LLVM's <ulink
     url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
     Variable Attribute</ulink>. Note that this function is defined as
     inline function.</para>

     <para><function>sd_bus_creds_ref()</function>,
     <function>sd_bus_creds_unref()</function> and
     <function>sd_bus_creds_unrefp()</function> execute no operation if
     the passed in bus credentials object is
     <constant>NULL</constant>.</para>

   </refsect1>

   <refsect1>
     <title>Return Value</title>

     <para>On success, <function>sd_bus_creds_new_from_pid()</function>
     returns 0 or a positive integer. On failure, it returns a negative
     errno-style error code.</para>

     <para><function>sd_bus_creds_get_mask()</function> returns the
     mask of successfully acquired fields.</para>

     <para><function>sd_bus_creds_get_augmented_mask()</function>
     returns the mask of fields that have been augmented from data in
     <filename>/proc</filename>, and are thus not suitable for
     authorization decisions.</para>

     <para><function>sd_bus_creds_ref()</function> always returns the
     argument.</para>

     <para><function>sd_bus_creds_unref()</function> always returns
     <constant>NULL</constant>.</para>
   </refsect1>

   <refsect1>
     <title>Reference ownership</title>

     <para>Function <function>sd_bus_creds_new_from_pid()</function>
     creates a new object and the caller owns the sole reference. When
     not needed anymore, this reference should be destroyed with
     <citerefentry><refentrytitle>sd_bus_creds_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
     </para>
   </refsect1>

   <refsect1>
     <title>Errors</title>

     <para>Returned errors may indicate the following problems:</para>

     <variablelist>

       <varlistentry>
         <term><constant>-ESRCH</constant></term>

         <listitem><para>Specified <parameter>pid</parameter> could not
         be found.</para></listitem>
       </varlistentry>

       <varlistentry>
         <term><constant>-EINVAL</constant></term>

         <listitem><para>Specified parameter is invalid
         (<constant>NULL</constant> in case of output
         parameters).</para></listitem>
       </varlistentry>

       <varlistentry>
         <term><constant>-ENOMEM</constant></term>

         <listitem><para>Memory allocation failed.</para></listitem>
       </varlistentry>

       <varlistentry>
         <term><constant>-EOPNOTSUPP</constant></term>

         <listitem><para>One of the requested fields is unknown to the local system.</para></listitem>
       </varlistentry>
     </variablelist>
   </refsect1>

   <refsect1>
     <title>Notes</title>

     <para><function>sd_bus_creds_new_from_pid()</function> and the
     other calls described here 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>
   </refsect1>

   <refsect1>
     <title>See Also</title>

     <para>
       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
     </para>
   </refsect1>

 </refentry>
	<?xml version='1.0'?> <!--- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil --->
	<!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 2014 Zbigniew Jędrzejewski-Szmek

	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_bus_creds_new_from_pid">

	<refentryinfo>
	<title>sd_bus_creds_new_from_pid</title>
	<productname>systemd</productname>

	<authorgroup>
	<author>
	<contrib>A monkey with a typewriter</contrib>
	<firstname>Zbigniew</firstname>
	<surname>Jędrzejewski-Szmek</surname>
	<email>zbyszek@in.waw.pl</email>
	</author>
	</authorgroup>
	</refentryinfo>

	<refmeta>
	<refentrytitle>sd_bus_creds_new_from_pid</refentrytitle>
	<manvolnum>3</manvolnum>
	</refmeta>

	<refnamediv>
	<refname>sd_bus_creds_new_from_pid</refname>
	<refname>sd_bus_creds_get_mask</refname>
	<refname>sd_bus_creds_get_augmented_mask</refname>
	<refname>sd_bus_creds_ref</refname>
	<refname>sd_bus_creds_unref</refname>
	<refname>sd_bus_creds_unrefp</refname>

	<refpurpose>Retrieve credentials object for the specified PID</refpurpose>
	</refnamediv>

	<refsynopsisdiv>
	<funcsynopsis>
	<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>

	<funcprototype>
	<funcdef>int <function>sd_bus_creds_new_from_pid</function></funcdef>
	<paramdef>pid_t <parameter>pid</parameter></paramdef>
	<paramdef>uint64_t <parameter>creds_mask</parameter></paramdef>
	<paramdef>sd_bus_creds **<parameter>ret</parameter></paramdef>
	</funcprototype>

	<funcprototype>
	<funcdef>uint64_t <function>sd_bus_creds_get_mask</function></funcdef>
	<paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
	</funcprototype>

	<funcprototype>
	<funcdef>uint64_t <function>sd_bus_creds_get_augmented_mask</function></funcdef>
	<paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
	</funcprototype>

	<funcprototype>
	<funcdef>sd_bus_creds *<function>sd_bus_creds_ref</function></funcdef>
	<paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
	</funcprototype>

	<funcprototype>
	<funcdef>sd_bus_creds *<function>sd_bus_creds_unref</function></funcdef>
	<paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
	</funcprototype>

	<funcprototype>
	<funcdef>void <function>sd_bus_creds_unrefp</function></funcdef>
	<paramdef>sd_bus_creds **<parameter>c</parameter></paramdef>
	</funcprototype>
	</funcsynopsis>

	<para>
	<constant>SD_BUS_CREDS_PID</constant>,
	<constant>SD_BUS_CREDS_PPID</constant>,
	<constant>SD_BUS_CREDS_TID</constant>,
	<constant>SD_BUS_CREDS_UID</constant>,
	<constant>SD_BUS_CREDS_EUID</constant>,
	<constant>SD_BUS_CREDS_SUID</constant>,
	<constant>SD_BUS_CREDS_FSUID</constant>,
	<constant>SD_BUS_CREDS_GID</constant>,
	<constant>SD_BUS_CREDS_EGID</constant>,
	<constant>SD_BUS_CREDS_SGID</constant>,
	<constant>SD_BUS_CREDS_FSGID</constant>,
	<constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>,
	<constant>SD_BUS_CREDS_COMM</constant>,
	<constant>SD_BUS_CREDS_TID_COMM</constant>,
	<constant>SD_BUS_CREDS_EXE</constant>,
	<constant>SD_BUS_CREDS_CMDLINE</constant>,
	<constant>SD_BUS_CREDS_CGROUP</constant>,
	<constant>SD_BUS_CREDS_UNIT</constant>,
	<constant>SD_BUS_CREDS_SLICE</constant>,
	<constant>SD_BUS_CREDS_USER_UNIT</constant>,
	<constant>SD_BUS_CREDS_USER_SLICE</constant>,
	<constant>SD_BUS_CREDS_SESSION</constant>,
	<constant>SD_BUS_CREDS_OWNER_UID</constant>,
	<constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>,
	<constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
	<constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>,
	<constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
	<constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>,
	<constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
	<constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>,
	<constant>SD_BUS_CREDS_TTY</constant>,
	<constant>SD_BUS_CREDS_UNIQUE_NAME</constant>,
	<constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>,
	<constant>SD_BUS_CREDS_DESCRIPTION</constant>,
	<constant>SD_BUS_CREDS_AUGMENT</constant>,
	<constant>_SD_BUS_CREDS_ALL</constant>
	</para>
	</refsynopsisdiv>

	<refsect1>
	<title>Description</title>

	<para><function>sd_bus_creds_new_from_pid()</function> creates a
	new credentials object and fills it with information about the
	process <parameter>pid</parameter>. The pointer to this object
	will be stored in the <parameter>ret</parameter> pointer. Note that
	credential objects may also be created and retrieved via
	<citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
	<citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
	and
	<citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>

	<para>The information that will be stored is determined by
	<parameter>creds_mask</parameter>. It may contain a subset of ORed
	constants <constant>SD_BUS_CREDS_PID</constant>,
	<constant>SD_BUS_CREDS_PPID</constant>,
	<constant>SD_BUS_CREDS_TID</constant>,
	<constant>SD_BUS_CREDS_UID</constant>,
	<constant>SD_BUS_CREDS_EUID</constant>,
	<constant>SD_BUS_CREDS_SUID</constant>,
	<constant>SD_BUS_CREDS_FSUID</constant>,
	<constant>SD_BUS_CREDS_GID</constant>,
	<constant>SD_BUS_CREDS_EGID</constant>,
	<constant>SD_BUS_CREDS_SGID</constant>,
	<constant>SD_BUS_CREDS_FSGID</constant>,
	<constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>,
	<constant>SD_BUS_CREDS_COMM</constant>,
	<constant>SD_BUS_CREDS_TID_COMM</constant>,
	<constant>SD_BUS_CREDS_EXE</constant>,
	<constant>SD_BUS_CREDS_CMDLINE</constant>,
	<constant>SD_BUS_CREDS_CGROUP</constant>,
	<constant>SD_BUS_CREDS_UNIT</constant>,
	<constant>SD_BUS_CREDS_SLICE</constant>,
	<constant>SD_BUS_CREDS_USER_UNIT</constant>,
	<constant>SD_BUS_CREDS_USER_SLICE</constant>,
	<constant>SD_BUS_CREDS_SESSION</constant>,
	<constant>SD_BUS_CREDS_OWNER_UID</constant>,
	<constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>,
	<constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
	<constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>,
	<constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
	<constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>,
	<constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
	<constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>,
	<constant>SD_BUS_CREDS_TTY</constant>,
	<constant>SD_BUS_CREDS_UNIQUE_NAME</constant>,
	<constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>, and
	<constant>SD_BUS_CREDS_DESCRIPTION</constant>. Use the special
	value <constant>_SD_BUS_CREDS_ALL</constant> to request all
	supported fields. The <constant>SD_BUS_CREDS_AUGMENT</constant>
	constant may not be ORed into the mask for invocations of
	<function>sd_bus_creds_new_from_pid()</function>.</para>

	<para>Fields can be retrieved from the credentials object using
	<citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
	and other functions which correspond directly to the constants
	listed above.</para>

	<para>A mask of fields which were actually successfully retrieved
	can be retrieved with
	<function>sd_bus_creds_get_mask()</function>. If the credentials
	object was created with
	<function>sd_bus_creds_new_from_pid()</function>, this will be a
	subset of fields requested in <parameter>creds_mask</parameter>.
	</para>

	<para>Similar to <function>sd_bus_creds_get_mask()</function>, the
	function <function>sd_bus_creds_get_augmented_mask()</function>
	returns a bitmask of field constants. The mask indicates which
	credential fields have been retrieved in a non-atomic fashion. For
	credential objects created via
	<function>sd_bus_creds_new_from_pid()</function>, this mask will be
	identical to the mask returned by
	<function>sd_bus_creds_get_mask()</function>. However, for
	credential objects retrieved via
	<function>sd_bus_get_name_creds()</function>, this mask will be set
	for the credential fields that could not be determined atomically
	at peer connection time, and which were later added by reading
	augmenting credential data from
	<filename>/proc</filename>. Similarly, for credential objects
	retrieved via <function>sd_bus_get_owner_creds()</function>, the
	mask is set for the fields that could not be determined atomically
	at bus creation time, but have been augmented. Similarly, for
	credential objects retrieved via
	<function>sd_bus_message_get_creds()</function>, the mask is set
	for the fields that could not be determined atomically at message
	sending time, but have been augmented. The mask returned by
	<function>sd_bus_creds_get_augmented_mask()</function> is always a
	subset of (or identical to) the mask returned by
	<function>sd_bus_creds_get_mask()</function> for the same
	object. The latter call hence returns all credential fields
	available in the credential object, the former then marks the
	subset of those that have been augmented. Note that augmented
	fields are unsuitable for authorization decisions, as they may be
	retrieved at different times, thus being subject to races. Hence,
	augmented fields should be used exclusively for informational
	purposes.
	</para>

	<para><function>sd_bus_creds_ref()</function> creates a new
	reference to the credentials object <parameter>c</parameter>. This
	object will not be destroyed until
	<function>sd_bus_creds_unref()</function> has been called as many
	times plus once more. Once the reference count has dropped to zero,
	<parameter>c</parameter> cannot be used anymore, so further
	calls to <function>sd_bus_creds_ref(c)</function> or
	<function>sd_bus_creds_unref(c)</function> are illegal.</para>

	<para><function>sd_bus_creds_unref()</function> destroys a reference
	to <parameter>c</parameter>.</para>

	<para><function>sd_bus_creds_unrefp()</function> is similar to
	<function>sd_bus_creds_unref()</function> but takes a pointer to a
	pointer to an <type>sd_bus_creds</type> object. This call is useful in
	conjunction with GCC's and LLVM's <ulink
	url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
	Variable Attribute</ulink>. Note that this function is defined as
	inline function.</para>

	<para><function>sd_bus_creds_ref()</function>,
	<function>sd_bus_creds_unref()</function> and
	<function>sd_bus_creds_unrefp()</function> execute no operation if
	the passed in bus credentials object is
	<constant>NULL</constant>.</para>

	</refsect1>

	<refsect1>
	<title>Return Value</title>

	<para>On success, <function>sd_bus_creds_new_from_pid()</function>
	returns 0 or a positive integer. On failure, it returns a negative
	errno-style error code.</para>

	<para><function>sd_bus_creds_get_mask()</function> returns the
	mask of successfully acquired fields.</para>

	<para><function>sd_bus_creds_get_augmented_mask()</function>
	returns the mask of fields that have been augmented from data in
	<filename>/proc</filename>, and are thus not suitable for
	authorization decisions.</para>

	<para><function>sd_bus_creds_ref()</function> always returns the
	argument.</para>

	<para><function>sd_bus_creds_unref()</function> always returns
	<constant>NULL</constant>.</para>
	</refsect1>

	<refsect1>
	<title>Reference ownership</title>

	<para>Function <function>sd_bus_creds_new_from_pid()</function>
	creates a new object and the caller owns the sole reference. When
	not needed anymore, this reference should be destroyed with
	<citerefentry><refentrytitle>sd_bus_creds_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
	</para>
	</refsect1>

	<refsect1>
	<title>Errors</title>

	<para>Returned errors may indicate the following problems:</para>

	<variablelist>

	<varlistentry>
	<term><constant>-ESRCH</constant></term>

	<listitem><para>Specified <parameter>pid</parameter> could not
	be found.</para></listitem>
	</varlistentry>

	<varlistentry>
	<term><constant>-EINVAL</constant></term>

	<listitem><para>Specified parameter is invalid
	(<constant>NULL</constant> in case of output
	parameters).</para></listitem>
	</varlistentry>

	<varlistentry>
	<term><constant>-ENOMEM</constant></term>

	<listitem><para>Memory allocation failed.</para></listitem>
	</varlistentry>

	<varlistentry>
	<term><constant>-EOPNOTSUPP</constant></term>

	<listitem><para>One of the requested fields is unknown to the local system.</para></listitem>
	</varlistentry>
	</variablelist>
	</refsect1>

	<refsect1>
	<title>Notes</title>

	<para><function>sd_bus_creds_new_from_pid()</function> and the
	other calls described here 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>
	</refsect1>

	<refsect1>
	<title>See Also</title>

	<para>
	<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
	<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
	<citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
	<citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
	<citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
	<citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
	</para>
	</refsect1>

	</refentry>