[gnome-session/wip/laney/systemd-user] Start sessions with systemd

[Iain Lane <iainl src gnome org>]

commit f12cf0070b397abd65f62336bf946299b561c2eb
Author: Iain Lane <iain orangesquash org uk>
Date:   Wed Jan 17 12:35:22 2018 +0000

    Start sessions with systemd
    
    We add a target and a unit to start GNOME Shell under systemd, instead
    of having gnome-session execute it directly.
    
    For now GDM's session is not included in this.
    
    The `gnome-session' script is responsible for setting up the environment
    that systemd will send to further processes spawned. Further work would
    be to move the environment setting code out of gnome-session itself.

 data/gnome-session.service.in    |   10 ++++++++++
 data/gnome-session.target        |    7 +++++++
 data/gnome.desktop.in            |    2 +-
 data/gnome.session.desktop.in.in |    2 +-
 data/meson.build                 |   21 +++++++++++++++++++++
 gnome-session/gnome-session.in   |   34 +++++++++++++++++++++++++++++++++-
 6 files changed, 73 insertions(+), 3 deletions(-)
---
diff --git a/data/gnome-session.service.in b/data/gnome-session.service.in
new file mode 100644
index 0000000..b299d8e
--- /dev/null
+++ b/data/gnome-session.service.in
@@ -0,0 +1,10 @@
+[Unit]
+Description=GNOME Session Manager
+PartOf=graphical-session.target
+After=graphical-session-pre.target
+Before=gnome-settings-daemon.target
+
+[Service]
+Type=dbus
+ExecStart=@libexecdir@/gnome-session-binary --session=gnome
+BusName=org.gnome.SessionManager
diff --git a/data/gnome-session.target b/data/gnome-session.target
new file mode 100644
index 0000000..6121111
--- /dev/null
+++ b/data/gnome-session.target
@@ -0,0 +1,7 @@
+[Unit]
+Description=User systemd services for the GNOME graphical session
+Requires=graphical-session-pre.target
+# start/tear down graphical-session.target along with the ubuntu session
+BindsTo=graphical-session.target
+# session leader -- if this dies, die along with it
+BindsTo=gnome-session.service
diff --git a/data/gnome.desktop.in b/data/gnome.desktop.in
index b54b99c..3d89a9f 100644
--- a/data/gnome.desktop.in
+++ b/data/gnome.desktop.in
@@ -1,7 +1,7 @@
 [Desktop Entry]
 _Name=GNOME
 _Comment=This session logs you into GNOME
-Exec=gnome-session
+Exec=gnome-session gnome.target
 TryExec=gnome-session
 Icon=
 Type=Application
diff --git a/data/gnome.session.desktop.in.in b/data/gnome.session.desktop.in.in
index f25cd25..276e219 100644
--- a/data/gnome.session.desktop.in.in
+++ b/data/gnome.session.desktop.in.in
@@ -1,3 +1,3 @@
 [GNOME Session]
 _Name=GNOME
-RequiredComponents=org.gnome.Shell;org.gnome.SettingsDaemon.A11yKeyboard;org.gnome.SettingsDaemon.A11ySettings;org.gnome.SettingsDaemon.Clipboard;org.gnome.SettingsDaemon.Color;org.gnome.SettingsDaemon.Datetime;org.gnome.SettingsDaemon.Housekeeping;org.gnome.SettingsDaemon.Keyboard;org.gnome.SettingsDaemon.MediaKeys;org.gnome.SettingsDaemon.Mouse;org.gnome.SettingsDaemon.Power;org.gnome.SettingsDaemon.PrintNotifications;org.gnome.SettingsDaemon.Rfkill;org.gnome.SettingsDaemon.ScreensaverProxy;org.gnome.SettingsDaemon.Sharing;org.gnome.SettingsDaemon.Smartcard;org.gnome.SettingsDaemon.Sound;org.gnome.SettingsDaemon.Wacom;org.gnome.SettingsDaemon.XSettings;
+RequiredComponents=
diff --git a/data/meson.build b/data/meson.build
index bf7ecfa..2136451 100644
--- a/data/meson.build
+++ b/data/meson.build
@@ -71,6 +71,27 @@ install_data(
   install_dir: join_paths(session_datadir, 'GConf', 'gsettings')
 )
 
+unit_conf = configuration_data()
+unit_conf.set('libexecdir', session_libexecdir)
+
+dep_systemd = dependency('systemd', required: true)
+systemd_unitdir = dep_systemd.get_pkgconfig_variable('systemduserunitdir')
+
+configure_file(
+  input: 'gnome-session.service.in',
+  output: 'gnome-session.service',
+  install: true,
+  install_dir: systemd_unitdir,
+  configuration: unit_conf
+)
+
+systemd_target = files('gnome-session.target')
+
+install_data(
+  systemd_target,
+  install_dir: systemd_unitdir
+)
+
 data = files('hardware-compatibility')
 
 if enable_session_selector
diff --git a/gnome-session/gnome-session.in b/gnome-session/gnome-session.in
index ce63df5..80920fa 100755
--- a/gnome-session/gnome-session.in
+++ b/gnome-session/gnome-session.in
@@ -25,4 +25,36 @@ if [ -n "$REGION" ]; then
   export LC_PAPER=$REGION
 fi
 
-exec @libexecdir@/gnome-session-binary "$@"
+if [ ${RUNNING_UNDER_GDM:-false} = true ]; then
+  # At the moment we don't run GDM in a full systemd session
+  exec /usr/lib/gnome-session/gnome-session-binary "$@"
+else
+  # stop any lingering active units from a previous session
+  systemctl --user stop --wait graphical-session.target graphical-session-pre.target
+
+  # robustness: if the previous graphical session left some failed units,
+  # reset them so that they don't break this startup
+  for unit in $(systemctl --user --no-legend --state=failed list-units | cut -f1 -d' '); do
+    if [ "$(systemctl --user show -p PartOf --value $unit)" = "graphical-session.target" ]; then
+      systemctl --user reset-failed $unit
+    fi
+  done
+
+  # subshell so we can unset environment variables
+  (
+    # unset login-session-specifics
+    unset XDG_SEAT
+    unset XDG_SESSION_ID
+    unset XDG_VTNR
+
+    unset DISPLAY
+
+    # tell dbus-daemon --session (and systemd --user, if running)
+    # to put the our current environment in activated services' environments
+
+    # XXX: Move this elsewhere (relocate the equivalent code in gnome-session
+    # itself to a standalone binary?)
+    dbus-update-activation-environment --verbose --systemd --all
+  )
+  systemctl --user start --wait "$@"
+fi