vm: move DVM template specific code into separate mixin

No functional change.

qubes/vm/appvm.py

@@ -24,10 +24,12 @@ import copy
 
 import qubes.events
 import qubes.vm.qubesvm
+import qubes.vm.mix.dvmtemplate
 from qubes.config import defaults
 
 
-class AppVM(qubes.vm.qubesvm.QubesVM):
+class AppVM(qubes.vm.mix.dvmtemplate.DVMTemplateMixin,
+        qubes.vm.qubesvm.QubesVM):
     '''Application VM'''
 
     template = qubes.VMProperty('template',
@@ -35,11 +37,6 @@ class AppVM(qubes.vm.qubesvm.QubesVM):
                                 vmclass=qubes.vm.templatevm.TemplateVM,
                                 doc='Template, on which this AppVM is based.')
 
-    template_for_dispvms = qubes.property('template_for_dispvms',
-        type=bool,
-        default=False,
-        doc='Should this VM be allowed to start as Disposable VM')
-
     default_volume_config = {
             'root': {
                 'name': 'root',
@@ -97,15 +94,6 @@ class AppVM(qubes.vm.qubesvm.QubesVM):
 
         super(AppVM, self).__init__(app, xml, **kwargs)
 
-    @property
-    def dispvms(self):
-        ''' Returns a generator containing all Disposable VMs based on the
-        current AppVM.
-        '''
-        for vm in self.app.domains:
-            if hasattr(vm, 'template') and vm.template is self:
-                yield vm
-
     @qubes.events.handler('domain-load')
     def on_domain_loaded(self, event):
         ''' When domain is loaded assert that this vm has a template.
@@ -126,10 +114,6 @@ class AppVM(qubes.vm.qubesvm.QubesVM):
         if not self.is_halted():
             raise qubes.exc.QubesVMNotHaltedError(self,
                 'Cannot change template while qube is running')
-        if any(self.dispvms):
-            raise qubes.exc.QubesVMInUseError(self,
-                'Cannot change template '
-                'while there are DispVMs based on this qube')
 
     @qubes.events.handler('property-set:template')
     def on_property_set_template(self, event, name, newvalue, oldvalue=None):

qubes/vm/mix/dvmtemplate.py

@@ -0,0 +1,47 @@
+# -*- encoding: utf-8 -*-
+#
+# The Qubes OS Project, http://www.qubes-os.org
+#
+# Copyright (C) 2017 Marek Marczykowski-Górecki
+#                               <marmarek@invisiblethingslab.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, see <http://www.gnu.org/licenses/>.
+
+import qubes.events
+
+class DVMTemplateMixin(qubes.events.Emitter):
+    '''VM class capable of being DVM template'''
+
+    template_for_dispvms = qubes.property('template_for_dispvms',
+        type=bool,
+        default=False,
+        doc='Should this VM be allowed to start as Disposable VM')
+
+    @qubes.events.handler('property-pre-set:template')
+    def __on_property_pre_set_template(self, event, name, newvalue,
+            oldvalue=None):
+        # pylint: disable=unused-argument
+        if any(self.dispvms):
+            raise qubes.exc.QubesVMInUseError(self,
+                'Cannot change template '
+                'while there are DispVMs based on this qube')
+
+    @property
+    def dispvms(self):
+        ''' Returns a generator containing all Disposable VMs based on the
+        current AppVM.
+        '''
+        for vm in self.app.domains:
+            if getattr(vm, 'template', None) == self:
+                yield vm

rpm_spec/core-dom0.spec.in

@@ -249,6 +249,7 @@ fi
 %dir %{python3_sitelib}/qubes/vm/mix/__pycache__
 %{python3_sitelib}/qubes/vm/mix/__pycache__/*
 %{python3_sitelib}/qubes/vm/mix/__init__.py
+%{python3_sitelib}/qubes/vm/mix/dvmtemplate.py
 %{python3_sitelib}/qubes/vm/mix/net.py
 
 %dir %{python3_sitelib}/qubes/storage