Added a servicevm feature extension

Used by vm.icon method, at the moment features['servicevm'] is set
when a VM provides_network.

qubes/ext/core_features.py

@@ -62,3 +62,25 @@ class CoreFeatures(qubes.ext.Extension):
             # if this is the first time qrexec was advertised, now can finish
             #  template setup
             yield from vm.fire_event_async('template-postinstall')
+
+    # pylint: disable=no-self-use
+    def set_servicevm_feature(self, subject):
+        if getattr(subject, 'provides_network', False):
+            subject.features['servicevm'] = 1
+        elif 'servicevm' in subject.features:
+            del subject.features['servicevm']
+
+    @qubes.ext.handler('property-set:provides_network')
+    def on_property_set(self, subject, event, name, newvalue, oldvalue=None):
+        # pylint: disable=unused-argument
+        self.set_servicevm_feature(subject)
+
+    @qubes.ext.handler('property-del:provides_network')
+    def on_property_del(self, subject, event, name):
+        # pylint: disable=unused-argument
+        self.set_servicevm_feature(subject)
+
+    @qubes.ext.handler('domain-load')
+    def on_domain_load(self, subject, event):
+        # pylint: disable=unused-argument
+        self.set_servicevm_feature(subject)

qubes/tests/ext.py

@@ -34,8 +34,11 @@ class TC_00_CoreFeatures(qubes.tests.QubesTestCase):
         self.features = {}
         self.vm.configure_mock(**{
             'features.get.side_effect': self.features.get,
+            'features.items.side_effect': self.features.items,
+            'features.__iter__.side_effect': self.features.__iter__,
             'features.__contains__.side_effect': self.features.__contains__,
             'features.__setitem__.side_effect': self.features.__setitem__,
+            'features.__delitem__.side_effect': self.features.__delitem__,
             })
 
     def test_010_notify_tools(self):
@@ -181,6 +184,16 @@ class TC_00_CoreFeatures(qubes.tests.QubesTestCase):
             ('features.__contains__', ('gui',), {}),
         ])
 
+    def test_100_servicevm_feature(self):
+        self.vm.provides_network = True
+        self.ext.set_servicevm_feature(self.vm)
+        self.assertEqual(self.features['servicevm'], 1)
+
+        self.vm.provides_network = False
+        self.ext.set_servicevm_feature(self.vm)
+        self.assertNotIn('servicevm', self.features)
+
+
 class TC_10_WindowsFeatures(qubes.tests.QubesTestCase):
     def setUp(self):
         super().setUp()