man: de-emphasize *_get_session()

Explanation:

"Please note the login session may be limited to a stub
 process or two.  User processes may instead be started from their
 systemd user manager, e.g. GUI applications started using DBus
 activation, as well as service processes which are shared between
 multiple logins of the same user."

The most glaring example being when you run commands from gnome-terminal,
or as you see nowadays, "gnome-terminal-server".

*_get_session() is still currently used (directly or indirectly) by Xorg,
Weston etc. running within the session scope.  That setup is perfectly
functional, although code will be more generally useful if it is able to
run outside the session scope.[1]

[1] https://wiki.archlinux.org/index.php/Systemd/User#Xorg_as_a_systemd_user_service

Re-order the man pages a bit at the same time.  This is to avoid having the
first and titular entry introduce the session concept, and then immediately
try and persuade you not to use it :).

diff --git a/man/rules/meson.build b/man/rules/meson.build
index ae0556058e6e9f66984fb28cd897e5787e7110d9..f74dbf9c77475f60a3ae9e2e9c8a8d214e05503d 100644 (file)
--- a/man/rules/meson.build
+++ b/man/rules/meson.build
@@ -441,7 +441,7 @@ manpages = [
   '3',
   ['sd_notifyf', 'sd_pid_notify', 'sd_pid_notify_with_fds', 'sd_pid_notifyf'],
   ''],
- ['sd_pid_get_session',
+ ['sd_pid_get_owner_uid',
   '3',
   ['sd_peer_get_cgroup',
    'sd_peer_get_machine_name',
@@ -453,7 +453,7 @@ manpages = [
    'sd_peer_get_user_unit',
    'sd_pid_get_cgroup',
    'sd_pid_get_machine_name',
-   'sd_pid_get_owner_uid',
+   'sd_pid_get_session',
    'sd_pid_get_slice',
    'sd_pid_get_unit',
    'sd_pid_get_user_slice',

diff --git a/man/sd_bus_creds_get_pid.xml b/man/sd_bus_creds_get_pid.xml
index 6ea95e0665fa86b8f04e8ee207a2ffc964c8202b..56e62863f2697e9a1cbc5def50a32b12dd34e522 100644 (file)
--- a/man/sd_bus_creds_get_pid.xml
+++ b/man/sd_bus_creds_get_pid.xml
@@ -394,16 +394,19 @@
 
     <para><function>sd_bus_creds_get_session()</function> will
     retrieve the identifier of the login session that the process is
-    a part of. See
-    <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. For
-    processes that are not part of a session, returns -ENXIO.
-    </para>
+    a part of. Please note the login session may be limited to a stub
+    process or two.  User processes may instead be started from their
+    systemd user manager, e.g. GUI applications started using DBus
+    activation, as well as service processes which are shared between
+    multiple logins of the same user. For processes that are not part
+    of a session, returns -ENXIO.</para>
 
     <para><function>sd_bus_creds_get_owner_uid()</function> will
     retrieve the numeric UID (user identifier) of the user who owns
-    the login session that the process is a part of. See
+    the user unit or login session that the process is a part of. See
     <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
-    For processes that are not part of a session, returns -ENXIO.
+    For processes that are not part of a user unit or session, returns
+    -ENXIO.
     </para>
 
     <para><function>sd_bus_creds_has_effective_cap()</function> will check whether the capability specified by
@@ -506,8 +509,10 @@
         <function>sd_bus_creds_get_user_slice()</function>, and
         <function>sd_bus_creds_get_session()</function> if the process is
         not part of a systemd system unit, systemd user unit, systemd
-        slice, or logind session. It will also be returned by
-        <function>sd_bus_creds_get_exe()</function> and
+        slice, or logind session. It will be returned by
+        <function>sd_bus_creds_get_owner_uid()</function> if the process is
+        not part of a systemd user unit or logind session. It will also be
+        returned by <function>sd_bus_creds_get_exe()</function> and
         <function>sd_bus_creds_get_cmdline()</function> for kernel
         threads (since these are not started from an executable binary,
         nor have a command line), and by

diff --git a/man/sd_pid_get_session.xml b/man/sd_pid_get_owner_uid.xml
similarity index 85%
rename from man/sd_pid_get_session.xml
rename to man/sd_pid_get_owner_uid.xml
index 14ebd53e36a23dab95bb5df0f49eff910af19403..5a2a07d096496481b9217bc7c700aff6f1271c9a 100644 (file)
--- a/man/sd_pid_get_session.xml
+++ b/man/sd_pid_get_owner_uid.xml
@@ -21,10 +21,10 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 -->
 
-<refentry id="sd_pid_get_session" conditional='HAVE_PAM'>
+<refentry id="sd_pid_get_owner_uid" conditional='HAVE_PAM'>
 
   <refentryinfo>
-    <title>sd_pid_get_session</title>
+    <title>sd_pid_get_owner_uid</title>
     <productname>systemd</productname>
 
     <authorgroup>
@@ -38,30 +38,30 @@
   </refentryinfo>
 
   <refmeta>
-    <refentrytitle>sd_pid_get_session</refentrytitle>
+    <refentrytitle>sd_pid_get_owner_uid</refentrytitle>
     <manvolnum>3</manvolnum>
   </refmeta>
 
   <refnamediv>
+    <refname>sd_pid_get_owner_uid</refname>
     <refname>sd_pid_get_session</refname>
-    <refname>sd_pid_get_unit</refname>
     <refname>sd_pid_get_user_unit</refname>
-    <refname>sd_pid_get_owner_uid</refname>
+    <refname>sd_pid_get_unit</refname>
     <refname>sd_pid_get_machine_name</refname>
     <refname>sd_pid_get_slice</refname>
     <refname>sd_pid_get_user_slice</refname>
     <refname>sd_pid_get_cgroup</refname>
+    <refname>sd_peer_get_owner_uid</refname>
     <refname>sd_peer_get_session</refname>
-    <refname>sd_peer_get_unit</refname>
     <refname>sd_peer_get_user_unit</refname>
-    <refname>sd_peer_get_owner_uid</refname>
+    <refname>sd_peer_get_unit</refname>
     <refname>sd_peer_get_machine_name</refname>
     <refname>sd_peer_get_slice</refname>
     <refname>sd_peer_get_user_slice</refname>
     <refname>sd_peer_get_cgroup</refname>
-    <refpurpose>Determine session, unit, owner of a session,
-    container/VM or slice of a specific PID or socket
-    peer</refpurpose>
+    <refpurpose>Determine the owner uid of the user unit or session,
+    or the session, user unit, system unit, container/VM or slice that
+    a specific PID or socket peer belongs to.</refpurpose>
   </refnamediv>
 
   <refsynopsisdiv>
@@ -69,15 +69,15 @@
       <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
 
       <funcprototype>
-        <funcdef>int <function>sd_pid_get_session</function></funcdef>
+        <funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
         <paramdef>pid_t <parameter>pid</parameter></paramdef>
-        <paramdef>char **<parameter>session</parameter></paramdef>
+        <paramdef>uid_t *<parameter>uid</parameter></paramdef>
       </funcprototype>
 
       <funcprototype>
-        <funcdef>int <function>sd_pid_get_unit</function></funcdef>
+        <funcdef>int <function>sd_pid_get_session</function></funcdef>
         <paramdef>pid_t <parameter>pid</parameter></paramdef>
-        <paramdef>char **<parameter>unit</parameter></paramdef>
+        <paramdef>char **<parameter>session</parameter></paramdef>
       </funcprototype>
 
       <funcprototype>
@@ -87,9 +87,9 @@
       </funcprototype>
 
       <funcprototype>
-        <funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
+        <funcdef>int <function>sd_pid_get_unit</function></funcdef>
         <paramdef>pid_t <parameter>pid</parameter></paramdef>
-        <paramdef>uid_t *<parameter>uid</parameter></paramdef>
+        <paramdef>char **<parameter>unit</parameter></paramdef>
       </funcprototype>
 
       <funcprototype>
@@ -117,15 +117,15 @@
       </funcprototype>
 
       <funcprototype>
-        <funcdef>int <function>sd_peer_get_session</function></funcdef>
+        <funcdef>int <function>sd_peer_get_owner_uid</function></funcdef>
         <paramdef>int <parameter>fd</parameter></paramdef>
-        <paramdef>char **<parameter>session</parameter></paramdef>
+        <paramdef>uid_t *<parameter>uid</parameter></paramdef>
       </funcprototype>
 
       <funcprototype>
-        <funcdef>int <function>sd_peer_get_unit</function></funcdef>
+        <funcdef>int <function>sd_peer_get_session</function></funcdef>
         <paramdef>int <parameter>fd</parameter></paramdef>
-        <paramdef>char **<parameter>unit</parameter></paramdef>
+        <paramdef>char **<parameter>session</parameter></paramdef>
       </funcprototype>
 
       <funcprototype>
@@ -135,9 +135,9 @@
       </funcprototype>
 
       <funcprototype>
-        <funcdef>int <function>sd_peer_get_owner_uid</function></funcdef>
+        <funcdef>int <function>sd_peer_get_unit</function></funcdef>
         <paramdef>int <parameter>fd</parameter></paramdef>
-        <paramdef>uid_t *<parameter>uid</parameter></paramdef>
+        <paramdef>char **<parameter>unit</parameter></paramdef>
       </funcprototype>
 
       <funcprototype>
@@ -169,16 +169,34 @@
   <refsect1>
     <title>Description</title>
 
+    <para><function>sd_pid_get_owner_uid()</function> may be used to
+    determine the Unix UID (user identifier) which owns the login
+    session or systemd user unit of a process identified by the
+    specified PID. For processes which are not part of a login session
+    and not managed by a user manager, this function will fail with
+    <constant>-ENODATA</constant>.</para>
+
     <para><function>sd_pid_get_session()</function> may be used to
     determine the login session identifier of a process identified by
     the specified process identifier. The session identifier is a
-    short string, suitable for usage in file system paths. Note that
-    not all processes are part of a login session (e.g. system service
-    processes, user processes that are shared between multiple
-    sessions of the same user, or kernel threads). For processes not
-    being part of a login session, this function will fail with
-    <constant>-ENODATA</constant>. The returned string needs to be freed with the libc
-    <citerefentry
+    short string, suitable for usage in file system paths. Please
+    note the login session may be limited to a stub process or two.
+    User processes may instead be started from their systemd user
+    manager, e.g. GUI applications started using DBus activation, as
+    well as service processes which are shared between multiple logins
+    of the same user. For processes which are not part of a login
+    session, this function will fail with <constant>-ENODATA</constant>.
+    The returned string needs to be freed with the libc <citerefentry
+    project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    call after use.</para>
+
+    <para><function>sd_pid_get_user_unit()</function> may be used to
+    determine the systemd user unit (i.e. user service or scope unit)
+    identifier of a process identified by the specified PID. The
+    unit name is a short string, suitable for usage in file system
+    paths. For processes which are not managed by a user manager, this
+    function will fail with <constant>-ENODATA</constant>. The
+    returned string needs to be freed with the libc <citerefentry
     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
     call after use.</para>
 
@@ -186,37 +204,21 @@
     determine the systemd system unit (i.e. system service or scope
     unit) identifier of a process identified by the specified PID. The
     unit name is a short string, suitable for usage in file system
-    paths. Note that not all processes are part of a system
-    unit/service (e.g. user processes, or kernel threads). For
-    processes not being part of a systemd system unit, this function
-    will fail with <constant>-ENODATA</constant>. (More specifically, this call will not
-    work for kernel threads.) The returned string needs to be freed
-    with the libc <citerefentry
+    paths.  Note that not all processes are part of a system
+    unit/service. For processes not being part of a systemd system
+    unit, this function will fail with <constant>-ENODATA</constant>.
+    (More specifically, this call will not work for kernel threads.)
+    The returned string needs to be freed with the libc <citerefentry
     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
     call after use.</para>
 
-    <para><function>sd_pid_get_user_unit()</function> may be used to
-    determine the systemd user unit (i.e. user service or scope unit)
-    identifier of a process identified by the specified PID. This is
-    similar to <function>sd_pid_get_unit()</function>, but applies to
-    user units instead of system units.</para>
-
-    <para><function>sd_pid_get_owner_uid()</function> may be used to
-    determine the Unix UID (user identifier) of the owner of the
-    session of a process identified the specified PID. Note that this
-    function will succeed for user processes which are shared between
-    multiple login sessions of the same user, whereas
-    <function>sd_pid_get_session()</function> will fail. For processes
-    not being part of a login session and not being a shared process
-    of a user, this function will fail with <constant>-ENODATA</constant>.</para>
-
     <para><function>sd_pid_get_machine_name()</function> may be used
     to determine the name of the VM or container is a member of. The
     machine name is a short string, suitable for usage in file system
     paths. The returned string needs to be freed with the libc
     <citerefentry
     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
-    call after use. For processes not part of a VM or containers, this
+    call after use. For processes not part of a VM or container, this
     function fails with <constant>-ENODATA</constant>.</para>
 
     <para><function>sd_pid_get_slice()</function> may be used to
@@ -246,10 +248,10 @@
     functions is passed as 0, the operation is executed for the
     calling process.</para>
 
-    <para>The <function>sd_peer_get_session()</function>,
-    <function>sd_peer_get_unit()</function>,
+    <para>The <function>sd_peer_get_owner_uid()</function>,
+    <function>sd_peer_get_session()</function>,
     <function>sd_peer_get_user_unit()</function>,
-    <function>sd_peer_get_owner_uid()</function>,
+    <function>sd_peer_get_unit()</function>,
     <function>sd_peer_get_machine_name()</function>,
     <function>sd_peer_get_slice()</function>,
     <function>sd_peer_get_user_slice()</function> and