man/sd_bus_creds_get_pid.xml

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   6   SPDX-License-Identifier: LGPL-2.1+
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   8   This file is part of systemd.
   9
  10   Copyright 2014 Zbigniew Jędrzejewski-Szmek
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  12
  13 <refentry id="sd_bus_creds_get_pid">
  14
  15   <refentryinfo>
  16     <title>sd_bus_creds_get_pid</title>
  17     <productname>systemd</productname>
  18
  19     <authorgroup>
  20       <author>
  21         <contrib>A monkey with a typewriter</contrib>
  22         <firstname>Zbigniew</firstname>
  23         <surname>Jędrzejewski-Szmek</surname>
  24         <email>zbyszek@in.waw.pl</email>
  25       </author>
  26     </authorgroup>
  27   </refentryinfo>
  28
  29   <refmeta>
  30     <refentrytitle>sd_bus_creds_get_pid</refentrytitle>
  31     <manvolnum>3</manvolnum>
  32   </refmeta>
  33
  34   <refnamediv>
  35     <refname>sd_bus_creds_get_pid</refname>
  36     <refname>sd_bus_creds_get_ppid</refname>
  37     <refname>sd_bus_creds_get_tid</refname>
  38     <refname>sd_bus_creds_get_uid</refname>
  39     <refname>sd_bus_creds_get_euid</refname>
  40     <refname>sd_bus_creds_get_suid</refname>
  41     <refname>sd_bus_creds_get_fsuid</refname>
  42     <refname>sd_bus_creds_get_gid</refname>
  43     <refname>sd_bus_creds_get_egid</refname>
  44     <refname>sd_bus_creds_get_sgid</refname>
  45     <refname>sd_bus_creds_get_fsgid</refname>
  46     <refname>sd_bus_creds_get_supplementary_gids</refname>
  47     <refname>sd_bus_creds_get_comm</refname>
  48     <refname>sd_bus_creds_get_tid_comm</refname>
  49     <refname>sd_bus_creds_get_exe</refname>
  50     <refname>sd_bus_creds_get_cmdline</refname>
  51     <refname>sd_bus_creds_get_cgroup</refname>
  52     <refname>sd_bus_creds_get_unit</refname>
  53     <refname>sd_bus_creds_get_slice</refname>
  54     <refname>sd_bus_creds_get_user_unit</refname>
  55     <refname>sd_bus_creds_get_user_slice</refname>
  56     <refname>sd_bus_creds_get_session</refname>
  57     <refname>sd_bus_creds_get_owner_uid</refname>
  58     <refname>sd_bus_creds_has_effective_cap</refname>
  59     <refname>sd_bus_creds_has_permitted_cap</refname>
  60     <refname>sd_bus_creds_has_inheritable_cap</refname>
  61     <refname>sd_bus_creds_has_bounding_cap</refname>
  62     <refname>sd_bus_creds_get_selinux_context</refname>
  63     <refname>sd_bus_creds_get_audit_session_id</refname>
  64     <refname>sd_bus_creds_get_audit_login_uid</refname>
  65     <refname>sd_bus_creds_get_tty</refname>
  66     <refname>sd_bus_creds_get_unique_name</refname>
  67     <refname>sd_bus_creds_get_well_known_names</refname>
  68     <refname>sd_bus_creds_get_description</refname>
  69
  70     <refpurpose>Retrieve fields from a credentials object</refpurpose>
  71   </refnamediv>
  72
  73   <refsynopsisdiv>
  74     <funcsynopsis>
  75       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  76
  77       <funcprototype>
  78         <funcdef>int <function>sd_bus_creds_get_pid</function></funcdef>
  79         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  80         <paramdef>pid_t *<parameter>pid</parameter></paramdef>
  81       </funcprototype>
  82
  83       <funcprototype>
  84         <funcdef>int <function>sd_bus_creds_get_ppid</function></funcdef>
  85         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  86         <paramdef>pid_t *<parameter>ppid</parameter></paramdef>
  87       </funcprototype>
  88
  89       <funcprototype>
  90         <funcdef>int <function>sd_bus_creds_get_tid</function></funcdef>
  91         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  92         <paramdef>pid_t *<parameter>tid</parameter></paramdef>
  93       </funcprototype>
  94
  95       <funcprototype>
  96         <funcdef>int <function>sd_bus_creds_get_uid</function></funcdef>
  97         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  98         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
  99       </funcprototype>
 100
 101       <funcprototype>
 102         <funcdef>int <function>sd_bus_creds_get_euid</function></funcdef>
 103         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 104         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 105       </funcprototype>
 106
 107       <funcprototype>
 108         <funcdef>int <function>sd_bus_creds_get_suid</function></funcdef>
 109         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 110         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 111       </funcprototype>
 112
 113       <funcprototype>
 114         <funcdef>int <function>sd_bus_creds_get_fsuid</function></funcdef>
 115         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 116         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 117       </funcprototype>
 118
 119       <funcprototype>
 120         <funcdef>int <function>sd_bus_creds_get_gid</function></funcdef>
 121         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 122         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 123       </funcprototype>
 124
 125       <funcprototype>
 126         <funcdef>int <function>sd_bus_creds_get_egid</function></funcdef>
 127         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 128         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 129       </funcprototype>
 130
 131       <funcprototype>
 132         <funcdef>int <function>sd_bus_creds_get_sgid</function></funcdef>
 133         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 134         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 135       </funcprototype>
 136
 137       <funcprototype>
 138         <funcdef>int <function>sd_bus_creds_get_fsgid</function></funcdef>
 139         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 140         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 141       </funcprototype>
 142
 143       <funcprototype>
 144         <funcdef>int <function>sd_bus_creds_get_supplementary_gids</function></funcdef>
 145         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 146         <paramdef>const gid_t **<parameter>gids</parameter></paramdef>
 147       </funcprototype>
 148
 149       <funcprototype>
 150         <funcdef>int <function>sd_bus_creds_get_comm</function></funcdef>
 151         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 152         <paramdef>const char **<parameter>comm</parameter></paramdef>
 153       </funcprototype>
 154
 155       <funcprototype>
 156         <funcdef>int <function>sd_bus_creds_get_tid_comm</function></funcdef>
 157         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 158         <paramdef>const char **<parameter>comm</parameter></paramdef>
 159       </funcprototype>
 160
 161       <funcprototype>
 162         <funcdef>int <function>sd_bus_creds_get_exe</function></funcdef>
 163         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 164         <paramdef>const char **<parameter>exe</parameter></paramdef>
 165       </funcprototype>
 166
 167       <funcprototype>
 168         <funcdef>int <function>sd_bus_creds_get_cmdline</function></funcdef>
 169         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 170         <paramdef>char ***<parameter>cmdline</parameter></paramdef>
 171       </funcprototype>
 172
 173       <funcprototype>
 174         <funcdef>int <function>sd_bus_creds_get_cgroup</function></funcdef>
 175         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 176         <paramdef>const char **<parameter>cgroup</parameter></paramdef>
 177       </funcprototype>
 178
 179       <funcprototype>
 180         <funcdef>int <function>sd_bus_creds_get_unit</function></funcdef>
 181         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 182         <paramdef>const char **<parameter>unit</parameter></paramdef>
 183       </funcprototype>
 184
 185       <funcprototype>
 186         <funcdef>int <function>sd_bus_creds_get_slice</function></funcdef>
 187         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 188         <paramdef>const char **<parameter>slice</parameter></paramdef>
 189       </funcprototype>
 190
 191       <funcprototype>
 192         <funcdef>int <function>sd_bus_creds_get_user_unit</function></funcdef>
 193         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 194         <paramdef>const char **<parameter>unit</parameter></paramdef>
 195       </funcprototype>
 196
 197       <funcprototype>
 198         <funcdef>int <function>sd_bus_creds_get_user_slice</function></funcdef>
 199         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 200         <paramdef>const char **<parameter>slice</parameter></paramdef>
 201       </funcprototype>
 202
 203       <funcprototype>
 204         <funcdef>int <function>sd_bus_creds_get_session</function></funcdef>
 205         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 206         <paramdef>const char **<parameter>slice</parameter></paramdef>
 207       </funcprototype>
 208
 209       <funcprototype>
 210         <funcdef>int <function>sd_bus_creds_get_owner_uid</function></funcdef>
 211         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 212         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 213       </funcprototype>
 214
 215       <funcprototype>
 216         <funcdef>int <function>sd_bus_creds_has_effective_cap</function></funcdef>
 217         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 218         <paramdef>int <parameter>capability</parameter></paramdef>
 219       </funcprototype>
 220
 221       <funcprototype>
 222         <funcdef>int <function>sd_bus_creds_has_permitted_cap</function></funcdef>
 223         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 224         <paramdef>int <parameter>capability</parameter></paramdef>
 225       </funcprototype>
 226
 227       <funcprototype>
 228         <funcdef>int <function>sd_bus_creds_has_inheritable_cap</function></funcdef>
 229         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 230         <paramdef>int <parameter>capability</parameter></paramdef>
 231       </funcprototype>
 232
 233       <funcprototype>
 234         <funcdef>int <function>sd_bus_creds_has_bounding_cap</function></funcdef>
 235         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 236         <paramdef>int <parameter>capability</parameter></paramdef>
 237       </funcprototype>
 238
 239       <funcprototype>
 240         <funcdef>int <function>sd_bus_creds_get_selinux_context</function></funcdef>
 241         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 242         <paramdef>const char **<parameter>context</parameter></paramdef>
 243       </funcprototype>
 244
 245       <funcprototype>
 246         <funcdef>int <function>sd_bus_creds_get_audit_session_id</function></funcdef>
 247         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 248         <paramdef>uint32_t *<parameter>sessionid</parameter></paramdef>
 249       </funcprototype>
 250
 251       <funcprototype>
 252         <funcdef>int <function>sd_bus_creds_get_audit_login_uid</function></funcdef>
 253         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 254         <paramdef>uid_t *<parameter>loginuid</parameter></paramdef>
 255       </funcprototype>
 256
 257       <funcprototype>
 258         <funcdef>int <function>sd_bus_creds_get_tty</function></funcdef>
 259         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 260         <paramdef>const char **<parameter>tty</parameter></paramdef>
 261       </funcprototype>
 262
 263       <funcprototype>
 264         <funcdef>int <function>sd_bus_creds_get_unique_name</function></funcdef>
 265         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 266         <paramdef>const char **<parameter>name</parameter></paramdef>
 267       </funcprototype>
 268
 269       <funcprototype>
 270         <funcdef>int <function>sd_bus_creds_get_well_known_names</function></funcdef>
 271         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 272         <paramdef>char ***<parameter>name</parameter></paramdef>
 273       </funcprototype>
 274
 275       <funcprototype>
 276         <funcdef>int <function>sd_bus_creds_get_description</function></funcdef>
 277         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 278         <paramdef>const char **<parameter>name</parameter></paramdef>
 279       </funcprototype>
 280
 281     </funcsynopsis>
 282   </refsynopsisdiv>
 283
 284   <refsect1>
 285     <title>Description</title>
 286
 287     <para>These functions return credential information from an
 288     <parameter>sd_bus_creds</parameter> object. Credential objects may
 289     be created with
 290     <citerefentry><refentrytitle>sd_bus_creds_new_from_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 291     in which case they describe the credentials of the process
 292     identified by the specified PID, with
 293     <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 294     in which case they describe the credentials of a bus peer
 295     identified by the specified bus name, with
 296     <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 297     in which case they describe the credentials of the creator of a
 298     bus, or with
 299     <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 300     in which case they describe the credentials of the sender of the
 301     message.</para>
 302
 303     <para>Not all credential fields are part of every
 304     <literal>sd_bus_creds</literal> object. Use
 305     <citerefentry><refentrytitle>sd_bus_creds_get_mask</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 306     to determine the mask of fields available.</para>
 307
 308     <para><function>sd_bus_creds_get_pid()</function> will retrieve
 309     the PID (process identifier). Similarly,
 310     <function>sd_bus_creds_get_ppid()</function> will retrieve the
 311     parent PID. Note that PID 1 has no parent process, in which case
 312     -ENXIO is returned.</para>
 313
 314     <para><function>sd_bus_creds_get_tid()</function> will retrieve the
 315     TID (thread identifier).</para>
 316
 317     <para><function>sd_bus_creds_get_uid()</function> will retrieve
 318     the numeric UID (user identifier). Similarly,
 319     <function>sd_bus_creds_get_euid()</function> returns the effective
 320     UID, <function>sd_bus_creds_get_suid()</function> the saved UID
 321     and <function>sd_bus_creds_get_fsuid()</function> the file system
 322     UID.</para>
 323
 324     <para><function>sd_bus_creds_get_gid()</function> will retrieve the
 325     numeric GID (group identifier). Similarly,
 326     <function>sd_bus_creds_get_egid()</function> returns the effective
 327     GID, <function>sd_bus_creds_get_sgid()</function> the saved GID
 328     and <function>sd_bus_creds_get_fsgid()</function> the file system
 329     GID.</para>
 330
 331     <para><function>sd_bus_creds_get_supplementary_gids()</function>
 332     will retrieve the supplementary GIDs list.</para>
 333
 334     <para><function>sd_bus_creds_get_comm()</function> will retrieve the
 335     comm field (truncated name of the executable, as stored in
 336     <filename>/proc/<replaceable>pid</replaceable>/comm</filename>).
 337     </para>
 338
 339     <para><function>sd_bus_creds_get_tid_comm()</function> will retrieve
 340     the comm field of the thread (as stored in
 341     <filename>/proc/<replaceable>pid</replaceable>/task/<replaceable>tid</replaceable>/comm</filename>).
 342     </para>
 343
 344     <para><function>sd_bus_creds_get_exe()</function> will retrieve
 345     the path to the program executable (as stored in the
 346     <filename>/proc/<replaceable>pid</replaceable>/exe</filename>
 347     link, but with the <literal> (deleted)</literal> suffix removed). Note
 348     that kernel threads do not have an executable path, in which case
 349     -ENXIO is returned.</para>
 350
 351     <para><function>sd_bus_creds_get_cmdline()</function> will
 352     retrieve an array of command line arguments (as stored in
 353     <filename>/proc/<replaceable>pid</replaceable>/cmdline</filename>). Note
 354     that kernel threads do not have a command line, in which case
 355     -ENXIO is returned.</para>
 356
 357     <para><function>sd_bus_creds_get_cgroup()</function> will retrieve
 358     the control group path. See <ulink
 359     url="https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt">cgroups.txt</ulink>.
 360     </para>
 361
 362     <para><function>sd_bus_creds_get_unit()</function> will retrieve
 363     the systemd unit name (in the system instance of systemd) that the
 364     process is a part of. See
 365     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. For
 366     processes that are not part of a unit, returns -ENXIO.
 367     </para>
 368
 369     <para><function>sd_bus_creds_get_user_unit()</function> will
 370     retrieve the systemd unit name (in the user instance of systemd)
 371     that the process is a part of. See
 372     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. For
 373     processes that are not part of a user unit, returns -ENXIO.
 374     </para>
 375
 376     <para><function>sd_bus_creds_get_slice()</function> will retrieve
 377     the systemd slice (a unit in the system instance of systemd) that
 378     the process is a part of. See
 379     <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Similarly,
 380     <function>sd_bus_creds_get_user_slice()</function> retrieves the
 381     systemd slice of the process, in the user instance of systemd.
 382     </para>
 383
 384     <para><function>sd_bus_creds_get_session()</function> will
 385     retrieve the identifier of the login session that the process is
 386     a part of. Please note the login session may be limited to a stub
 387     process or two.  User processes may instead be started from their
 388     systemd user manager, e.g. GUI applications started using DBus
 389     activation, as well as service processes which are shared between
 390     multiple logins of the same user. For processes that are not part
 391     of a session, returns -ENXIO.</para>
 392
 393     <para><function>sd_bus_creds_get_owner_uid()</function> will
 394     retrieve the numeric UID (user identifier) of the user who owns
 395     the user unit or login session that the process is a part of. See
 396     <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 397     For processes that are not part of a user unit or session, returns
 398     -ENXIO.
 399     </para>
 400
 401     <para><function>sd_bus_creds_has_effective_cap()</function> will check whether the capability specified by
 402     <parameter>capability</parameter> was set in the effective capabilities mask. A positive return value means that it
 403     was set, zero means that it was not set, and a negative return value indicates an error. See <citerefentry
 404     project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> and the
 405     <varname>AmbientCapabilities=</varname> and <varname>CapabilityBoundingSet=</varname> settings in
 406     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 407     </para>
 408
 409     <para><function>sd_bus_creds_has_permitted_cap()</function> is
 410     similar to <function>sd_bus_creds_has_effective_cap()</function>,
 411     but will check the permitted capabilities mask.</para>
 412
 413     <para><function>sd_bus_creds_has_inheritable_cap()</function> is
 414     similar to <function>sd_bus_creds_has_effective_cap()</function>,
 415     but will check the inheritable capabilities mask.</para>
 416
 417     <para><function>sd_bus_creds_has_bounding_cap()</function> is
 418     similar to <function>sd_bus_creds_has_effective_cap()</function>,
 419     but will check the bounding capabilities mask.</para>
 420
 421     <para><function>sd_bus_creds_get_selinux_context()</function> will
 422     retrieve the SELinux security context (label) of the process.</para>
 423
 424     <para><function>sd_bus_creds_get_audit_session_id()</function>
 425     will retrieve the audit session identifier of the process. Returns
 426     -ENXIO for processes that are not part of an audit session.</para>
 427
 428     <para><function>sd_bus_creds_get_audit_login_uid()</function> will
 429     retrieve the audit user login identifier (the identifier of the
 430     user who is "responsible" for the session). Returns -ENXIO for
 431     processes that are not part of an audit session.</para>
 432
 433     <para><function>sd_bus_creds_get_tty()</function> will retrieve
 434     the controlling TTY, without the prefixing "/dev/". Returns -ENXIO
 435     for processes that have no controlling TTY.</para>
 436
 437     <para><function>sd_bus_creds_get_unique_name()</function> will
 438     retrieve the D-Bus unique name. See <ulink
 439     url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus">The
 440     D-Bus specification</ulink>.</para>
 441
 442     <para><function>sd_bus_creds_get_well_known_names()</function> will
 443     retrieve the set of D-Bus well-known names. See <ulink
 444     url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus">The
 445     D-Bus specification</ulink>.</para>
 446
 447     <para><function>sd_bus_creds_get_description()</function> will
 448     retrieve a descriptive name of the bus connection of the
 449     peer. This name is useful to discern multiple bus connections by
 450     the same peer, and may be altered by the peer with the
 451     <citerefentry><refentrytitle>sd_bus_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 452     call.</para>
 453
 454     <para>All functions that take a <parameter>const
 455     char**</parameter> parameter will store the answer there as an
 456     address of a NUL-terminated string. It will be valid as long as
 457     <parameter>c</parameter> remains valid, and should not be freed or
 458     modified by the caller.</para>
 459
 460     <para>All functions that take a <parameter>char***</parameter>
 461     parameter will store the answer there as an address of an array
 462     of strings. Each individual string is NUL-terminated, and the
 463     array is NULL-terminated as a whole. It will be valid as long as
 464     <parameter>c</parameter> remains valid, and should not be freed or
 465     modified by the caller.</para>
 466   </refsect1>
 467
 468   <refsect1>
 469     <title>Return Value</title>
 470
 471     <para>On success, these calls return 0 or a positive integer. On
 472     failure, these calls return a negative errno-style error code.
 473     </para>
 474   </refsect1>
 475
 476   <refsect1>
 477     <title>Errors</title>
 478
 479     <para>Returned errors may indicate the following problems:</para>
 480
 481     <variablelist>
 482       <varlistentry>
 483         <term><constant>-ENODATA</constant></term>
 484
 485         <listitem><para>The given field is not available in the
 486         credentials object <parameter>c</parameter>.</para>
 487         </listitem>
 488       </varlistentry>
 489
 490       <varlistentry>
 491         <term><constant>-ENXIO</constant></term>
 492
 493         <listitem><para>The given field is not specified for the described
 494         process or peer. This will be returned by
 495         <function>sd_bus_creds_get_unit()</function>,
 496         <function>sd_bus_creds_get_slice()</function>,
 497         <function>sd_bus_creds_get_user_unit()</function>,
 498         <function>sd_bus_creds_get_user_slice()</function>, and
 499         <function>sd_bus_creds_get_session()</function> if the process is
 500         not part of a systemd system unit, systemd user unit, systemd
 501         slice, or logind session. It will be returned by
 502         <function>sd_bus_creds_get_owner_uid()</function> if the process is
 503         not part of a systemd user unit or logind session. It will also be
 504         returned by <function>sd_bus_creds_get_exe()</function> and
 505         <function>sd_bus_creds_get_cmdline()</function> for kernel
 506         threads (since these are not started from an executable binary,
 507         nor have a command line), and by
 508         <function>sd_bus_creds_get_audit_session_id()</function> and
 509         <function>sd_bus_creds_get_audit_login_uid()</function> when
 510         the process is not part of an audit session, and
 511         <function>sd_bus_creds_get_tty()</function> if the process has
 512         no controlling TTY.
 513         </para>
 514         </listitem>
 515       </varlistentry>
 516
 517       <varlistentry>
 518         <term><constant>-EINVAL</constant></term>
 519
 520         <listitem><para>Specified pointer parameter is <constant>NULL</constant>.
 521         </para></listitem>
 522       </varlistentry>
 523
 524       <varlistentry>
 525         <term><constant>-ENOMEM</constant></term>
 526
 527         <listitem><para>Memory allocation failed.</para></listitem>
 528       </varlistentry>
 529     </variablelist>
 530   </refsect1>
 531
 532   <refsect1>
 533     <title>Notes</title>
 534
 535     <para><function>sd_bus_creds_get_pid()</function> and the other
 536     functions described here are available as a shared library, which
 537     can be compiled and linked to with the
 538     <constant>libsystemd</constant> <citerefentry
 539     project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 540     file.</para>
 541   </refsect1>
 542
 543   <refsect1>
 544     <title>See Also</title>
 545
 546     <para>
 547       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 548       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 549       <citerefentry><refentrytitle>sd_bus_creds_new_from_pid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 550       <citerefentry project='man-pages'><refentrytitle>fork</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 551       <citerefentry project='man-pages'><refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 552       <citerefentry project='man-pages'><refentrytitle>credentials</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 553       <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 554       <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 555       <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 556     </para>
 557   </refsect1>
 558
 559 </refentry>