man/sd_pid_get_session.xml

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  23
  24 <refentry id="sd_pid_get_session" conditional='HAVE_PAM'>
  25
  26   <refentryinfo>
  27     <title>sd_pid_get_session</title>
  28     <productname>systemd</productname>
  29
  30     <authorgroup>
  31       <author>
  32         <contrib>Developer</contrib>
  33         <firstname>Lennart</firstname>
  34         <surname>Poettering</surname>
  35         <email>lennart@poettering.net</email>
  36       </author>
  37     </authorgroup>
  38   </refentryinfo>
  39
  40   <refmeta>
  41     <refentrytitle>sd_pid_get_session</refentrytitle>
  42     <manvolnum>3</manvolnum>
  43   </refmeta>
  44
  45   <refnamediv>
  46     <refname>sd_pid_get_session</refname>
  47     <refname>sd_pid_get_unit</refname>
  48     <refname>sd_pid_get_user_unit</refname>
  49     <refname>sd_pid_get_owner_uid</refname>
  50     <refname>sd_pid_get_machine_name</refname>
  51     <refname>sd_pid_get_slice</refname>
  52     <refname>sd_pid_get_user_slice</refname>
  53     <refname>sd_peer_get_session</refname>
  54     <refname>sd_peer_get_unit</refname>
  55     <refname>sd_peer_get_user_unit</refname>
  56     <refname>sd_peer_get_owner_uid</refname>
  57     <refname>sd_peer_get_machine_name</refname>
  58     <refname>sd_peer_get_slice</refname>
  59     <refname>sd_peer_get_user_slice</refname>
  60     <refpurpose>Determine session, unit, owner of a session,
  61     container/VM or slice of a specific PID or socket
  62     peer</refpurpose>
  63   </refnamediv>
  64
  65   <refsynopsisdiv>
  66     <funcsynopsis>
  67       <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
  68
  69       <funcprototype>
  70         <funcdef>int <function>sd_pid_get_session</function></funcdef>
  71         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  72         <paramdef>char **<parameter>session</parameter></paramdef>
  73       </funcprototype>
  74
  75       <funcprototype>
  76         <funcdef>int <function>sd_pid_get_unit</function></funcdef>
  77         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  78         <paramdef>char **<parameter>unit</parameter></paramdef>
  79       </funcprototype>
  80
  81       <funcprototype>
  82         <funcdef>int <function>sd_pid_get_user_unit</function></funcdef>
  83         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  84         <paramdef>char **<parameter>unit</parameter></paramdef>
  85       </funcprototype>
  86
  87       <funcprototype>
  88         <funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
  89         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  90         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
  91       </funcprototype>
  92
  93       <funcprototype>
  94         <funcdef>int <function>sd_pid_get_machine_name</function></funcdef>
  95         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  96         <paramdef>char **<parameter>name</parameter></paramdef>
  97       </funcprototype>
  98
  99       <funcprototype>
 100         <funcdef>int <function>sd_pid_get_slice</function></funcdef>
 101         <paramdef>pid_t <parameter>pid</parameter></paramdef>
 102         <paramdef>char **<parameter>slice</parameter></paramdef>
 103       </funcprototype>
 104
 105       <funcprototype>
 106         <funcdef>int <function>sd_pid_get_user_slice</function></funcdef>
 107         <paramdef>pid_t <parameter>pid</parameter></paramdef>
 108         <paramdef>char **<parameter>slice</parameter></paramdef>
 109       </funcprototype>
 110
 111       <funcprototype>
 112         <funcdef>int <function>sd_peer_get_session</function></funcdef>
 113         <paramdef>int <parameter>fd</parameter></paramdef>
 114         <paramdef>char **<parameter>session</parameter></paramdef>
 115       </funcprototype>
 116
 117       <funcprototype>
 118         <funcdef>int <function>sd_peer_get_unit</function></funcdef>
 119         <paramdef>int <parameter>fd</parameter></paramdef>
 120         <paramdef>char **<parameter>unit</parameter></paramdef>
 121       </funcprototype>
 122
 123       <funcprototype>
 124         <funcdef>int <function>sd_peer_get_user_unit</function></funcdef>
 125         <paramdef>int <parameter>fd</parameter></paramdef>
 126         <paramdef>char **<parameter>unit</parameter></paramdef>
 127       </funcprototype>
 128
 129       <funcprototype>
 130         <funcdef>int <function>sd_peer_get_owner_uid</function></funcdef>
 131         <paramdef>int <parameter>fd</parameter></paramdef>
 132         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 133       </funcprototype>
 134
 135       <funcprototype>
 136         <funcdef>int <function>sd_peer_get_machine_name</function></funcdef>
 137         <paramdef>int <parameter>fd</parameter></paramdef>
 138         <paramdef>char **<parameter>name</parameter></paramdef>
 139       </funcprototype>
 140
 141       <funcprototype>
 142         <funcdef>int <function>sd_peer_get_slice</function></funcdef>
 143         <paramdef>int <parameter>fd</parameter></paramdef>
 144         <paramdef>char **<parameter>slice</parameter></paramdef>
 145       </funcprototype>
 146
 147       <funcprototype>
 148         <funcdef>int <function>sd_peer_get_user_slice</function></funcdef>
 149         <paramdef>int <parameter>fd</parameter></paramdef>
 150         <paramdef>char **<parameter>slice</parameter></paramdef>
 151       </funcprototype>
 152     </funcsynopsis>
 153   </refsynopsisdiv>
 154
 155   <refsect1>
 156     <title>Description</title>
 157
 158     <para><function>sd_pid_get_session()</function> may be used to
 159     determine the login session identifier of a process identified by
 160     the specified process identifier. The session identifier is a
 161     short string, suitable for usage in file system paths. Note that
 162     not all processes are part of a login session (e.g. system service
 163     processes, user processes that are shared between multiple
 164     sessions of the same user, or kernel threads). For processes not
 165     being part of a login session this function will fail with
 166     -ENXIO. The returned string needs to be freed with the libc
 167     <citerefentry
 168     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 169     call after use.</para>
 170
 171     <para><function>sd_pid_get_unit()</function> may be used to
 172     determine the systemd system unit (i.e. system service or scope
 173     unit) identifier of a process identified by the specified PID. The
 174     unit name is a short string, suitable for usage in file system
 175     paths. Note that not all processes are part of a system
 176     unit/service (e.g. user processes, or kernel threads). For
 177     processes not being part of a systemd system unit this function
 178     will fail with -ENXIO (More specifically: this call will not work
 179     for kernel threads.) The returned string needs to be freed with
 180     the libc <citerefentry
 181     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 182     call after use.</para>
 183
 184     <para><function>sd_pid_get_user_unit()</function> may be used to
 185     determine the systemd user unit (i.e. user service or scope unit)
 186     identifier of a process identified by the specified PID. This is
 187     similar to <function>sd_pid_get_unit()</function> but applies to
 188     user units instead of system units.</para>
 189
 190     <para><function>sd_pid_get_owner_uid()</function> may be used to
 191     determine the Unix UID (user identifier) of the owner of the
 192     session of a process identified the specified PID. Note that this
 193     function will succeed for user processes which are shared between
 194     multiple login sessions of the same user, where
 195     <function>sd_pid_get_session()</function> will fail. For processes
 196     not being part of a login session and not being a shared process
 197     of a user this function will fail with -ENXIO.</para>
 198
 199     <para><function>sd_pid_get_machine_name()</function> may be used
 200     to determine the name of the VM or container is a member of. The
 201     machine name is a short string, suitable for usage in file system
 202     paths. The returned string needs to be freed with the libc
 203     <citerefentry
 204     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 205     call after use. For processes not part of a VM or containers this
 206     function fails with -ENXIO.</para>
 207
 208     <para><function>sd_pid_get_slice()</function> may be used to
 209     determine the slice unit the process is a member of. See
 210     <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 211     for details about slices. The returned string needs to be freed
 212     with the libc
 213     <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 214     call after use.</para>
 215
 216     <para>Similar, <function>sd_pid_get_user_slice()</function>
 217     returns the user slice (as managed by the user's systemd instance)
 218     of a process.</para>
 219
 220     <para>If the <varname>pid</varname> parameter of any of these
 221     functions is passed as 0, the operation is executed for the
 222     calling process.</para>
 223
 224     <para>The <function>sd_peer_get_session()</function>,
 225     <function>sd_peer_get_unit()</function>,
 226     <function>sd_peer_get_user_unit()</function>,
 227     <function>sd_peer_get_owner_uid()</function>,
 228     <function>sd_peer_get_machine_name()</function>,
 229     <function>sd_peer_get_slice()</function> and
 230     <function>sd_peer_get_user_slice()</function> calls operate
 231     similar to their PID counterparts, but operate on a connected
 232     AF_UNIX socket and retrieve information about the connected peer
 233     process. Note that these fields are retrieved via
 234     <filename>/proc</filename>, and hence are not suitable for
 235     authorization purposes, as they are subject to races.</para>
 236   </refsect1>
 237
 238   <refsect1>
 239     <title>Return Value</title>
 240
 241     <para>On success, these calls return 0 or a positive integer. On
 242     failure, these calls return a negative errno-style error
 243     code.</para>
 244   </refsect1>
 245
 246   <refsect1>
 247     <title>Errors</title>
 248
 249     <para>Returned errors may indicate the following problems:</para>
 250
 251     <variablelist>
 252
 253       <varlistentry>
 254         <term><constant>-ENXIO</constant></term>
 255
 256         <listitem><para>Given field is not specified for the described
 257         process or peer.</para>
 258         </listitem>
 259       </varlistentry>
 260
 261       <varlistentry>
 262         <term><constant>-ESRCH</constant></term>
 263
 264         <listitem><para>The specified PID does not refer to a running
 265         process.</para>
 266         </listitem>
 267       </varlistentry>
 268
 269       <varlistentry>
 270         <term><constant>-ENOMEM</constant></term>
 271
 272         <listitem><para>Memory allocation failed.</para></listitem>
 273       </varlistentry>
 274     </variablelist>
 275   </refsect1>
 276
 277   <refsect1>
 278     <title>Notes</title>
 279
 280     <para>The <function>sd_pid_get_session()</function>,
 281     <function>sd_pid_get_unit()</function>,
 282     <function>sd_pid_get_user_unit()</function>,
 283     <function>sd_pid_get_owner_uid()</function>,
 284     <function>sd_pid_get_machine_name()</function>,
 285     <function>sd_pid_get_slice()</function>,
 286     <function>sd_pid_get_user_slice()</function>,
 287     <function>sd_peer_get_session()</function>,
 288     <function>sd_peer_get_unit()</function>,
 289     <function>sd_peer_get_user_unit()</function>,
 290     <function>sd_peer_get_owner_uid()</function>,
 291     <function>sd_peer_get_machine_name()</function>,
 292     <function>sd_peer_get_slice()</function> and
 293     <function>sd_peer_get_user_slice()</function> interfaces are
 294     available as a shared library, which can be compiled and linked to
 295     with the <constant>libsystemd</constant> <citerefentry
 296     project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 297     file.</para>
 298
 299     <para>Note that the login session identifier as
 300     returned by <function>sd_pid_get_session()</function>
 301     is completely unrelated to the process session
 302     identifier as returned by
 303     <citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>.</para>
 304   </refsect1>
 305
 306   <refsect1>
 307     <title>See Also</title>
 308
 309     <para>
 310       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 311       <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 312       <citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 313       <citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 314       <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 315       <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 316     </para>
 317   </refsect1>
 318
 319 </refentry>