Add a lightdm session for sys-gui

Starts just sys-gui VM and qvm-start-daemon in a special mode.

See QubesOS/qubes-issues#5662.

Makefile

@@ -13,8 +13,11 @@ install:
 	install -d $(DESTDIR)/etc/xdg/autostart
 	install -m 0644 etc/qvm-start-daemon.desktop $(DESTDIR)/etc/xdg/autostart/
 	install -m 0644 etc/qvm-start-daemon-kde.desktop $(DESTDIR)/etc/xdg/autostart/
+	install -d $(DESTDIR)/usr/share/xsessions/
+	install -m 0644 xsessions/sys-gui.desktop $(DESTDIR)/usr/share/xsessions/
 	install -d $(DESTDIR)/usr/bin
 	ln -sf qvm-start-daemon $(DESTDIR)/usr/bin/qvm-start-gui
+	install -m 0755 scripts/qubes-gui-session $(DESTDIR)/usr/bin/
 
 clean:
 	rm -rf test-packages/__pycache__ qubesadmin/__pycache__

doc/manpages/qvm-start-daemon.rst

@@ -47,7 +47,11 @@ Options
 
 .. option:: --watch
 
-   Keep watching for further domains startups, must be used with --all
+   Keep watching for further domains startups
+
+.. option:: --exit
+
+   Exit after all watched domains have exited
 
 .. option:: --force-stubdomain
 

etc/sys-gui.desktop

@@ -0,0 +1,4 @@
+[Desktop Entry]
+Name=GUI Domain (sys-gui)
+Exec=qubes-gui-session sys-gui
+Type=Application

qubesadmin/tools/qvm_start_daemon.py

@@ -27,6 +27,8 @@
 import re
 import functools
 import sys
+import logging
+
 import xcffib
 import xcffib.xproto  # pylint: disable=unused-import
 
@@ -46,6 +48,8 @@
 except ImportError:
     pass
 
+logger = logging.getLogger('qvm-start-daemon')
+
 GUI_DAEMON_PATH = '/usr/bin/qubes-guid'
 PACAT_DAEMON_PATH = '/usr/bin/pacat-simple-vchan'
 QUBES_ICON_DIR = '/usr/share/icons/hicolor/128x128/devices'
@@ -322,14 +326,24 @@ def get_monitor_layout():
 class DAEMONLauncher:
     """Launch GUI/AUDIO daemon for VMs"""
 
-    def __init__(self, app: qubesadmin.app.QubesBase):
+    def __init__(self,
+                 app: qubesadmin.app.QubesBase,
+                 vms,
+                 exit_after_vms,
+                 kde):
         """ Initialize DAEMONLauncher.
 
         :param app: :py:class:`qubesadmin.Qubes` instance
+        :param vms: VMs to watch for, or None if watching for all
+        :param exit_after_vms: exit when all VMs are finished
         """
         self.app = app
-        self.started_processes = {}
-        self.kde = False
+        self.vms = vms
+        self.exit_after_vms = exit_after_vms
+        self.kde = kde
+
+        self.started_vms = set()
+        self.cancel = None
 
     @asyncio.coroutine
     def send_monitor_layout(self, vm, layout=None, startup=False):
@@ -596,6 +610,9 @@ def start_audio(self, vm):
 
     def on_domain_spawn(self, vm, _event, **kwargs):
         """Handler of 'domain-spawn' event, starts GUI daemon for stubdomain"""
+        if not self.is_watched(vm):
+            return
+
         try:
             if getattr(vm, 'guivm', None) != vm.app.local_name:
                 return
@@ -610,6 +627,11 @@ def on_domain_spawn(self, vm, _event, **kwargs):
     def on_domain_start(self, vm, _event, **kwargs):
         """Handler of 'domain-start' event, starts GUI/AUDIO daemon for
         actual VM """
+        if not self.is_watched(vm):
+            return
+
+        self.started_vms.add(vm)
+
         try:
             if getattr(vm, 'guivm', None) == vm.app.local_name and \
                     vm.features.check_with_template('gui', True) and \
@@ -636,24 +658,42 @@ def on_connection_established(self, _subject, _event, **_kwargs):
             if vm.klass == 'AdminVM':
                 continue
 
+            if not self.is_watched(vm):
+                continue
+
             power_state = vm.get_power_state()
             if power_state == 'Running':
                 asyncio.ensure_future(
                     self.start_gui(vm, monitor_layout=monitor_layout))
                 asyncio.ensure_future(self.start_audio(vm))
+                self.started_vms.add(vm)
             elif power_state == 'Transient':
                 # it is still starting, we'll get 'domain-start'
                 # event when fully started
                 if vm.virt_mode == 'hvm':
                     asyncio.ensure_future(
                         self.start_gui_for_stubdomain(vm))
 
+        if self.exit_after_vms and not self.started_vms:
+            logger.info('No VMs started yet, exiting')
+            self.cancel()
+
     def on_domain_stopped(self, vm, _event, **_kwargs):
         """Handler of 'domain-stopped' event, cleans up"""
+        if not self.is_watched(vm):
+            return
+
         self.cleanup_guid(vm.xid)
         if vm.virt_mode == 'hvm':
             self.cleanup_guid(vm.stubdom_xid)
 
+        if vm not in self.started_vms:
+            logger.warning('VM not in started_vms: %s', vm)
+        self.started_vms.remove(vm)
+        if self.exit_after_vms and not self.started_vms:
+            logger.info('All VMs stopped, exiting')
+            self.cancel()
+
     def cleanup_guid(self, xid):
         """
         Clean up after qubes-guid. Removes the auto-generated configuration
@@ -672,6 +712,20 @@ def register_events(self, events):
                            self.on_connection_established)
         events.add_handler('domain-stopped', self.on_domain_stopped)
 
+    def set_cancel(self, cancel):
+        """Set a 'cancel' callback in case of early exit"""
+        self.cancel = cancel
+
+    def is_watched(self, vm):
+        '''
+        Should we watch this VM for changes
+        '''
+
+        if self.vms is None:
+            return True
+        return vm in self.vms
+
+
 if 'XDG_RUNTIME_DIR' in os.environ:
     pidfile_path = os.path.join(os.environ['XDG_RUNTIME_DIR'],
                                 'qvm-start-daemon.pid')
@@ -683,7 +737,9 @@ def register_events(self, events):
     description='start GUI for qube(s)', vmname_nargs='*')
 parser.add_argument('--watch', action='store_true',
                     help='Keep watching for further domains'
-                         ' startups, must be used with --all')
+                         ' startups')
+parser.add_argument('--exit', action='store_true',
+                    help='Exit when all domains exit')
 parser.add_argument('--force-stubdomain', action='store_true',
                     help='Start GUI to stubdomain-emulated VGA,'
                          ' even if gui-agent is running in the VM')
@@ -710,11 +766,15 @@ def main(args=None):
         print(parser.format_help())
         return
     args = parser.parse_args(args)
-    if args.watch and not args.all_domains:
-        parser.error('--watch option must be used with --all')
     if args.watch and args.notify_monitor_layout:
         parser.error('--watch cannot be used with --notify-monitor-layout')
-    launcher = DAEMONLauncher(args.app)
+
+    launcher = DAEMONLauncher(
+        args.app,
+        vms=None if args.all_domains else args.domains,
+        exit_after_vms=args.exit,
+        kde=args.kde,
+    )
     if args.kde:
         launcher.kde = True
     if args.watch:
@@ -728,6 +788,7 @@ def main(args=None):
             launcher.register_events(events)
 
             events_listener = asyncio.ensure_future(events.listen_for_events())
+            launcher.set_cancel(events_listener.cancel)
 
             for signame in ('SIGINT', 'SIGTERM'):
                 loop.add_signal_handler(getattr(signal, signame),

rpm_spec/qubes-core-admin-client.spec.in

@@ -60,6 +60,7 @@ make -C doc DESTDIR=$RPM_BUILD_ROOT \
 %{_bindir}/qvm-*
 %{_mandir}/man1/qvm-*.1*
 %{_mandir}/man1/qubes*.1*
+%{_datadir}/xsessions/sys-gui.desktop
 
 %files -n python%{python3_pkgversion}-qubesadmin
 %{python3_sitelib}/qubesadmin-*egg-info

scripts/qubes-gui-session

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+print_usage() {
+cat >&2 <<USAGE
+Usage: $0 vmname
+Starts given VM and runs its associated GUI daemon. Used as X session for the
+GUI domain.
+USAGE
+}
+
+if [ $# -lt 1 ] ; then
+    print_usage
+    exit 1
+fi
+
+qvm-start sys-gui
+exec qvm-start-daemon --watch --exit "$1"

xsessions/sys-gui.desktop

@@ -0,0 +1,4 @@
+[Desktop Entry]
+Name=GUI Domain (sys-gui)
+Exec=qubes-gui-session
+Type=Application