man/sd_bus_creds_get_pid.xml

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  23
  24 <refentry id="sd_bus_creds_get_pid">
  25
  26   <refentryinfo>
  27     <title>sd_bus_creds_get_pid</title>
  28     <productname>systemd</productname>
  29
  30     <authorgroup>
  31       <author>
  32         <contrib>A monkey with a typewriter</contrib>
  33         <firstname>Zbigniew</firstname>
  34         <surname>Jędrzejewski-Szmek</surname>
  35         <email>zbyszek@in.waw.pl</email>
  36       </author>
  37     </authorgroup>
  38   </refentryinfo>
  39
  40   <refmeta>
  41     <refentrytitle>sd_bus_creds_get_pid</refentrytitle>
  42     <manvolnum>3</manvolnum>
  43   </refmeta>
  44
  45   <refnamediv>
  46     <refname>sd_bus_creds_get_pid</refname>
  47     <refname>sd_bus_creds_get_ppid</refname>
  48     <refname>sd_bus_creds_get_tid</refname>
  49     <refname>sd_bus_creds_get_uid</refname>
  50     <refname>sd_bus_creds_get_euid</refname>
  51     <refname>sd_bus_creds_get_suid</refname>
  52     <refname>sd_bus_creds_get_fsuid</refname>
  53     <refname>sd_bus_creds_get_gid</refname>
  54     <refname>sd_bus_creds_get_egid</refname>
  55     <refname>sd_bus_creds_get_sgid</refname>
  56     <refname>sd_bus_creds_get_fsgid</refname>
  57     <refname>sd_bus_creds_get_supplementary_gids</refname>
  58     <refname>sd_bus_creds_get_comm</refname>
  59     <refname>sd_bus_creds_get_tid_comm</refname>
  60     <refname>sd_bus_creds_get_exe</refname>
  61     <refname>sd_bus_creds_get_cmdline</refname>
  62     <refname>sd_bus_creds_get_cgroup</refname>
  63     <refname>sd_bus_creds_get_unit</refname>
  64     <refname>sd_bus_creds_get_slice</refname>
  65     <refname>sd_bus_creds_get_user_unit</refname>
  66     <refname>sd_bus_creds_get_user_slice</refname>
  67     <refname>sd_bus_creds_get_session</refname>
  68     <refname>sd_bus_creds_get_owner_uid</refname>
  69     <refname>sd_bus_creds_has_effective_cap</refname>
  70     <refname>sd_bus_creds_has_permitted_cap</refname>
  71     <refname>sd_bus_creds_has_inheritable_cap</refname>
  72     <refname>sd_bus_creds_has_bounding_cap</refname>
  73     <refname>sd_bus_creds_get_selinux_context</refname>
  74     <refname>sd_bus_creds_get_audit_session_id</refname>
  75     <refname>sd_bus_creds_get_audit_login_uid</refname>
  76     <refname>sd_bus_creds_get_tty</refname>
  77     <refname>sd_bus_creds_get_unique_name</refname>
  78     <refname>sd_bus_creds_get_well_known_names</refname>
  79     <refname>sd_bus_creds_get_description</refname>
  80
  81     <refpurpose>Retrieve fields from a credentials object</refpurpose>
  82   </refnamediv>
  83
  84   <refsynopsisdiv>
  85     <funcsynopsis>
  86       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  87
  88       <funcprototype>
  89         <funcdef>int <function>sd_bus_creds_get_pid</function></funcdef>
  90         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  91         <paramdef>pid_t *<parameter>pid</parameter></paramdef>
  92       </funcprototype>
  93
  94       <funcprototype>
  95         <funcdef>int <function>sd_bus_creds_get_ppid</function></funcdef>
  96         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  97         <paramdef>pid_t *<parameter>ppid</parameter></paramdef>
  98       </funcprototype>
  99
 100       <funcprototype>
 101         <funcdef>int <function>sd_bus_creds_get_tid</function></funcdef>
 102         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 103         <paramdef>pid_t *<parameter>tid</parameter></paramdef>
 104       </funcprototype>
 105
 106       <funcprototype>
 107         <funcdef>int <function>sd_bus_creds_get_uid</function></funcdef>
 108         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 109         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 110       </funcprototype>
 111
 112       <funcprototype>
 113         <funcdef>int <function>sd_bus_creds_get_euid</function></funcdef>
 114         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 115         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 116       </funcprototype>
 117
 118       <funcprototype>
 119         <funcdef>int <function>sd_bus_creds_get_suid</function></funcdef>
 120         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 121         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 122       </funcprototype>
 123
 124       <funcprototype>
 125         <funcdef>int <function>sd_bus_creds_get_fsuid</function></funcdef>
 126         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 127         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 128       </funcprototype>
 129
 130       <funcprototype>
 131         <funcdef>int <function>sd_bus_creds_get_gid</function></funcdef>
 132         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 133         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 134       </funcprototype>
 135
 136       <funcprototype>
 137         <funcdef>int <function>sd_bus_creds_get_egid</function></funcdef>
 138         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 139         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 140       </funcprototype>
 141
 142       <funcprototype>
 143         <funcdef>int <function>sd_bus_creds_get_sgid</function></funcdef>
 144         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 145         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 146       </funcprototype>
 147
 148       <funcprototype>
 149         <funcdef>int <function>sd_bus_creds_get_fsgid</function></funcdef>
 150         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 151         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 152       </funcprototype>
 153
 154       <funcprototype>
 155         <funcdef>int <function>sd_bus_creds_get_supplementary_gids</function></funcdef>
 156         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 157         <paramdef>const gid_t **<parameter>gids</parameter></paramdef>
 158       </funcprototype>
 159
 160       <funcprototype>
 161         <funcdef>int <function>sd_bus_creds_get_comm</function></funcdef>
 162         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 163         <paramdef>const char **<parameter>comm</parameter></paramdef>
 164       </funcprototype>
 165
 166       <funcprototype>
 167         <funcdef>int <function>sd_bus_creds_get_tid_comm</function></funcdef>
 168         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 169         <paramdef>const char **<parameter>comm</parameter></paramdef>
 170       </funcprototype>
 171
 172       <funcprototype>
 173         <funcdef>int <function>sd_bus_creds_get_exe</function></funcdef>
 174         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 175         <paramdef>const char **<parameter>exe</parameter></paramdef>
 176       </funcprototype>
 177
 178       <funcprototype>
 179         <funcdef>int <function>sd_bus_creds_get_cmdline</function></funcdef>
 180         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 181         <paramdef>char ***<parameter>cmdline</parameter></paramdef>
 182       </funcprototype>
 183
 184       <funcprototype>
 185         <funcdef>int <function>sd_bus_creds_get_cgroup</function></funcdef>
 186         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 187         <paramdef>const char **<parameter>cgroup</parameter></paramdef>
 188       </funcprototype>
 189
 190       <funcprototype>
 191         <funcdef>int <function>sd_bus_creds_get_unit</function></funcdef>
 192         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 193         <paramdef>const char **<parameter>unit</parameter></paramdef>
 194       </funcprototype>
 195
 196       <funcprototype>
 197         <funcdef>int <function>sd_bus_creds_get_slice</function></funcdef>
 198         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 199         <paramdef>const char **<parameter>slice</parameter></paramdef>
 200       </funcprototype>
 201
 202       <funcprototype>
 203         <funcdef>int <function>sd_bus_creds_get_user_unit</function></funcdef>
 204         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 205         <paramdef>const char **<parameter>unit</parameter></paramdef>
 206       </funcprototype>
 207
 208       <funcprototype>
 209         <funcdef>int <function>sd_bus_creds_get_user_slice</function></funcdef>
 210         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 211         <paramdef>const char **<parameter>slice</parameter></paramdef>
 212       </funcprototype>
 213
 214       <funcprototype>
 215         <funcdef>int <function>sd_bus_creds_get_session</function></funcdef>
 216         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 217         <paramdef>const char **<parameter>slice</parameter></paramdef>
 218       </funcprototype>
 219
 220       <funcprototype>
 221         <funcdef>int <function>sd_bus_creds_get_owner_uid</function></funcdef>
 222         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 223         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 224       </funcprototype>
 225
 226       <funcprototype>
 227         <funcdef>int <function>sd_bus_creds_has_effective_cap</function></funcdef>
 228         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 229         <paramdef>int <parameter>capability</parameter></paramdef>
 230       </funcprototype>
 231
 232       <funcprototype>
 233         <funcdef>int <function>sd_bus_creds_has_permitted_cap</function></funcdef>
 234         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 235         <paramdef>int <parameter>capability</parameter></paramdef>
 236       </funcprototype>
 237
 238       <funcprototype>
 239         <funcdef>int <function>sd_bus_creds_has_inheritable_cap</function></funcdef>
 240         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 241         <paramdef>int <parameter>capability</parameter></paramdef>
 242       </funcprototype>
 243
 244       <funcprototype>
 245         <funcdef>int <function>sd_bus_creds_has_bounding_cap</function></funcdef>
 246         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 247         <paramdef>int <parameter>capability</parameter></paramdef>
 248       </funcprototype>
 249
 250       <funcprototype>
 251         <funcdef>int <function>sd_bus_creds_get_selinux_context</function></funcdef>
 252         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 253         <paramdef>const char **<parameter>context</parameter></paramdef>
 254       </funcprototype>
 255
 256       <funcprototype>
 257         <funcdef>int <function>sd_bus_creds_get_audit_session_id</function></funcdef>
 258         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 259         <paramdef>uint32_t *<parameter>sessionid</parameter></paramdef>
 260       </funcprototype>
 261
 262       <funcprototype>
 263         <funcdef>int <function>sd_bus_creds_get_audit_login_uid</function></funcdef>
 264         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 265         <paramdef>uid_t *<parameter>loginuid</parameter></paramdef>
 266       </funcprototype>
 267
 268       <funcprototype>
 269         <funcdef>int <function>sd_bus_creds_get_tty</function></funcdef>
 270         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 271         <paramdef>const char **<parameter>tty</parameter></paramdef>
 272       </funcprototype>
 273
 274       <funcprototype>
 275         <funcdef>int <function>sd_bus_creds_get_unique_name</function></funcdef>
 276         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 277         <paramdef>const char **<parameter>name</parameter></paramdef>
 278       </funcprototype>
 279
 280       <funcprototype>
 281         <funcdef>int <function>sd_bus_creds_get_well_known_names</function></funcdef>
 282         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 283         <paramdef>char ***<parameter>name</parameter></paramdef>
 284       </funcprototype>
 285
 286       <funcprototype>
 287         <funcdef>int <function>sd_bus_creds_get_description</function></funcdef>
 288         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 289         <paramdef>const char **<parameter>name</parameter></paramdef>
 290       </funcprototype>
 291
 292     </funcsynopsis>
 293   </refsynopsisdiv>
 294
 295   <refsect1>
 296     <title>Description</title>
 297
 298     <para>These functions return credential information from an
 299     <parameter>sd_bus_creds</parameter> object. Credential objects may
 300     be created with
 301     <citerefentry><refentrytitle>sd_bus_creds_new_from_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 302     in which case they describe the credentials of the process
 303     identified by the specified PID, with
 304     <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 305     in which case they describe the credentials of a bus peer
 306     identified by the specified bus name, with
 307     <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 308     in which case they describe the credentials of the creator of a
 309     bus, or with
 310     <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 311     in which case they describe the credentials of the sender of the
 312     message.</para>
 313
 314     <para>Not all credential fields are part of every
 315     <literal>sd_bus_creds</literal> object. Use
 316     <citerefentry><refentrytitle>sd_bus_creds_get_mask</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 317     to determine the mask of fields available.</para>
 318
 319     <para><function>sd_bus_creds_get_pid()</function> will retrieve
 320     the PID (process identifier). Similarly,
 321     <function>sd_bus_creds_get_ppid()</function> will retrieve the
 322     parent PID. Note that PID 1 has no parent process, in which case
 323     -ENXIO is returned.</para>
 324
 325     <para><function>sd_bus_creds_get_tid()</function> will retrieve the
 326     TID (thread identifier).</para>
 327
 328     <para><function>sd_bus_creds_get_uid()</function> will retrieve
 329     the numeric UID (user identifier). Similarly,
 330     <function>sd_bus_creds_get_euid()</function> returns the effective
 331     UID, <function>sd_bus_creds_get_suid()</function> the saved UID
 332     and <function>sd_bus_creds_get_fsuid()</function> the file system
 333     UID.</para>
 334
 335     <para><function>sd_bus_creds_get_gid()</function> will retrieve the
 336     numeric GID (group identifier). Similarly,
 337     <function>sd_bus_creds_get_egid()</function> returns the effective
 338     GID, <function>sd_bus_creds_get_sgid()</function> the saved GID
 339     and <function>sd_bus_creds_get_fsgid()</function> the file system
 340     GID.</para>
 341
 342     <para><function>sd_bus_creds_get_supplementary_gids()</function>
 343     will retrieve the supplementary GIDs list.</para>
 344
 345     <para><function>sd_bus_creds_get_comm()</function> will retrieve the
 346     comm field (truncated name of the executable, as stored in
 347     <filename>/proc/<replaceable>pid</replaceable>/comm</filename>).
 348     </para>
 349
 350     <para><function>sd_bus_creds_get_tid_comm()</function> will retrieve
 351     the comm field of the thread (as stored in
 352     <filename>/proc/<replaceable>pid</replaceable>/task/<replaceable>tid</replaceable>/comm</filename>).
 353     </para>
 354
 355     <para><function>sd_bus_creds_get_exe()</function> will retrieve
 356     the path to the program executable (as stored in the
 357     <filename>/proc/<replaceable>pid</replaceable>/exe</filename>
 358     link, but with the <literal> (deleted)</literal> suffix removed). Note
 359     that kernel threads do not have an executable path, in which case
 360     -ENXIO is returned.</para>
 361
 362     <para><function>sd_bus_creds_get_cmdline()</function> will
 363     retrieve an array of command line arguments (as stored in
 364     <filename>/proc/<replaceable>pid</replaceable>/cmdline</filename>). Note
 365     that kernel threads do not have a command line, in which case
 366     -ENXIO is returned.</para>
 367
 368     <para><function>sd_bus_creds_get_cgroup()</function> will retrieve
 369     the cgroup path. See <ulink
 370     url="https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>.
 371     </para>
 372
 373     <para><function>sd_bus_creds_get_unit()</function> will retrieve
 374     the systemd unit name (in the system instance of systemd) that the
 375     process is a part of. See
 376     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. For
 377     processes that are not part of a unit, returns -ENXIO.
 378     </para>
 379
 380     <para><function>sd_bus_creds_get_user_unit()</function> will
 381     retrieve the systemd unit name (in the user instance of systemd)
 382     that the process is a part of. See
 383     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. For
 384     processes that are not part of a user unit, returns -ENXIO.
 385     </para>
 386
 387     <para><function>sd_bus_creds_get_slice()</function> will retrieve
 388     the systemd slice (a unit in the system instance of systemd) that
 389     the process is a part of. See
 390     <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Similarly,
 391     <function>sd_bus_creds_get_user_slice()</function> retrieves the
 392     systemd slice of the process, in the user instance of systemd.
 393     </para>
 394
 395     <para><function>sd_bus_creds_get_session()</function> will
 396     retrieve the identifier of the login session that the process is
 397     a part of. See
 398     <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. For
 399     processes that are not part of a session, returns -ENXIO.
 400     </para>
 401
 402     <para><function>sd_bus_creds_get_owner_uid()</function> will
 403     retrieve the numeric UID (user identifier) of the user who owns
 404     the login session that the process is a part of. See
 405     <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 406     For processes that are not part of a session, returns -ENXIO.
 407     </para>
 408
 409     <para><function>sd_bus_creds_has_effective_cap()</function> will check whether the capability specified by
 410     <parameter>capability</parameter> was set in the effective capabilities mask. A positive return value means that it
 411     was set, zero means that it was not set, and a negative return value indicates an error. See <citerefentry
 412     project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> and the
 413     <varname>AmbientCapabilities=</varname> and <varname>CapabilityBoundingSet=</varname> settings in
 414     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 415     </para>
 416
 417     <para><function>sd_bus_creds_has_permitted_cap()</function> is
 418     similar to <function>sd_bus_creds_has_effective_cap()</function>,
 419     but will check the permitted capabilities mask.</para>
 420
 421     <para><function>sd_bus_creds_has_inheritable_cap()</function> is
 422     similar to <function>sd_bus_creds_has_effective_cap()</function>,
 423     but will check the inheritable capabilities mask.</para>
 424
 425     <para><function>sd_bus_creds_has_bounding_cap()</function> is
 426     similar to <function>sd_bus_creds_has_effective_cap()</function>,
 427     but will check the bounding capabilities mask.</para>
 428
 429     <para><function>sd_bus_creds_get_selinux_context()</function> will
 430     retrieve the SELinux security context (label) of the process.</para>
 431
 432     <para><function>sd_bus_creds_get_audit_session_id()</function>
 433     will retrieve the audit session identifier of the process. Returns
 434     -ENXIO for processes that are not part of an audit session.</para>
 435
 436     <para><function>sd_bus_creds_get_audit_login_uid()</function> will
 437     retrieve the audit user login identifier (the identifier of the
 438     user who is "responsible" for the session). Returns -ENXIO for
 439     processes that are not part of an audit session.</para>
 440
 441     <para><function>sd_bus_creds_get_tty()</function> will retrieve
 442     the controlling TTY, without the prefixing "/dev/". Returns -ENXIO
 443     for processes that have no controlling TTY.</para>
 444
 445     <para><function>sd_bus_creds_get_unique_name()</function> will
 446     retrieve the D-Bus unique name. See <ulink
 447     url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus">The
 448     D-Bus specification</ulink>.</para>
 449
 450     <para><function>sd_bus_creds_get_well_known_names()</function> will
 451     retrieve the set of D-Bus well-known names. See <ulink
 452     url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus">The
 453     D-Bus specification</ulink>.</para>
 454
 455     <para><function>sd_bus_creds_get_description()</function> will
 456     retrieve a descriptive name of the bus connection of the
 457     peer. This name is useful to discern multiple bus connections by
 458     the same peer, and may be altered by the peer with the
 459     <citerefentry><refentrytitle>sd_bus_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 460     call.</para>
 461
 462     <para>All functions that take a <parameter>const
 463     char**</parameter> parameter will store the answer there as an
 464     address of a NUL-terminated string. It will be valid as long as
 465     <parameter>c</parameter> remains valid, and should not be freed or
 466     modified by the caller.</para>
 467
 468     <para>All functions that take a <parameter>char***</parameter>
 469     parameter will store the answer there as an address of an array
 470     of strings. Each individual string is NUL-terminated, and the
 471     array is NULL-terminated as a whole. It will be valid as long as
 472     <parameter>c</parameter> remains valid, and should not be freed or
 473     modified by the caller.</para>
 474   </refsect1>
 475
 476   <refsect1>
 477     <title>Return Value</title>
 478
 479     <para>On success, these calls return 0 or a positive integer. On
 480     failure, these calls return a negative errno-style error code.
 481     </para>
 482   </refsect1>
 483
 484   <refsect1>
 485     <title>Errors</title>
 486
 487     <para>Returned errors may indicate the following problems:</para>
 488
 489     <variablelist>
 490       <varlistentry>
 491         <term><constant>-ENODATA</constant></term>
 492
 493         <listitem><para>The given field is not available in the
 494         credentials object <parameter>c</parameter>.</para>
 495         </listitem>
 496       </varlistentry>
 497
 498       <varlistentry>
 499         <term><constant>-ENXIO</constant></term>
 500
 501         <listitem><para>The given field is not specified for the described
 502         process or peer. This will be returned by
 503         <function>sd_bus_get_unit()</function>,
 504         <function>sd_bus_get_slice()</function>,
 505         <function>sd_bus_get_user_unit()</function>,
 506         <function>sd_bus_get_user_slice()</function>,
 507         <function>sd_bus_get_session()</function>, and
 508         <function>sd_bus_get_owner_uid()</function> if the process is
 509         not part of a systemd system unit, systemd user unit, systemd
 510         slice, or logind session. It will also be returned by
 511         <function>sd_bus_creds_get_exe()</function> and
 512         <function>sd_bus_creds_get_cmdline()</function> for kernel
 513         threads (since these are not started from an executable binary,
 514         nor have a command line), and by
 515         <function>sd_bus_creds_get_audit_session_id()</function> and
 516         <function>sd_bus_creds_get_audit_login_uid()</function> when
 517         the process is not part of an audit session, and
 518         <function>sd_bus_creds_get_tty()</function> if the process has
 519         no controlling TTY.
 520         </para>
 521         </listitem>
 522       </varlistentry>
 523
 524       <varlistentry>
 525         <term><constant>-EINVAL</constant></term>
 526
 527         <listitem><para>Specified pointer parameter is <constant>NULL</constant>.
 528         </para></listitem>
 529       </varlistentry>
 530
 531       <varlistentry>
 532         <term><constant>-ENOMEM</constant></term>
 533
 534         <listitem><para>Memory allocation failed.</para></listitem>
 535       </varlistentry>
 536     </variablelist>
 537   </refsect1>
 538
 539   <refsect1>
 540     <title>Notes</title>
 541
 542     <para><function>sd_bus_creds_get_pid()</function> and the other
 543     functions described here are available as a shared library, which
 544     can be compiled and linked to with the
 545     <constant>libsystemd</constant> <citerefentry
 546     project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 547     file.</para>
 548   </refsect1>
 549
 550   <refsect1>
 551     <title>See Also</title>
 552
 553     <para>
 554       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 555       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 556       <citerefentry><refentrytitle>sd_bus_creds_new_from_pid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 557       <citerefentry project='man-pages'><refentrytitle>fork</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 558       <citerefentry project='man-pages'><refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 559       <citerefentry project='man-pages'><refentrytitle>credentials</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 560       <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 561       <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 562       <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 563     </para>
 564   </refsect1>
 565
 566 </refentry>