Fix saving 'updates-available' flag reported by TemplateBasedVM

Look for the first updateable template up in the template chain, instead
of going just one level up. Especially this applies to
DispVM -> AppVM -> TemplateVM case.
If DispVM reports available updates, 'updates-available'
flag should be set on relevant TemplateVM, not AppVM (*-dvm).

Include test for the new case.

Fixes QubesOS/qubes-issues#3736

qubes/api/misc.py

@@ -108,14 +108,20 @@ class QubesMiscAPI(qubes.api.AbstractQubesAPI):
         update_count = int(untrusted_update_count)
         del untrusted_update_count
 
+        # look for the nearest updateable VM up in the template chain
+        updateable_template = getattr(self.src, 'template', None)
+        while updateable_template is not None and \
+                not updateable_template.updateable:
+            updateable_template = getattr(updateable_template, 'template', None)
+
         if self.src.updateable:
             # Just trust information from VM itself
             self.src.features['updates-available'] = bool(update_count)
             self.app.save()
-        elif getattr(self.src, 'template', None) is not None:
+        elif updateable_template is not None:
             # Hint about updates availability in template
             # If template is running - it will notify about updates itself
-            if self.src.template.is_running():
+            if updateable_template.is_running():
                 return
             # Ignore no-updates info
             if update_count > 0:
@@ -123,6 +129,6 @@ class QubesMiscAPI(qubes.api.AbstractQubesAPI):
                 # in the template - ignore info
                 if self.src.storage.outdated_volumes:
                     return
-                self.src.template.features['updates-available'] = bool(
+                updateable_template.features['updates-available'] = bool(
                     update_count)
                 self.app.save()

qubes/tests/api_misc.py

@@ -249,6 +249,7 @@ class TC_00_API_Misc(qubes.tests.QubesTestCase):
         response = self.call_mgmt_func(b'qubes.NotifyUpdates', payload=b'0\n')
         self.assertIsNone(response)
         self.assertEqual(self.tpl.mock_calls, [
+            mock.call.updateable.__bool__(),
             mock.call.is_running(),
         ])
         self.assertEqual(self.app.mock_calls, [])
@@ -262,6 +263,7 @@ class TC_00_API_Misc(qubes.tests.QubesTestCase):
         self.assertIsNone(response)
         self.assertEqual(self.src.mock_calls, [])
         self.assertEqual(self.tpl.mock_calls, [
+            mock.call.updateable.__bool__(),
             mock.call.is_running(),
             mock.call.features.__setitem__('updates-available', True),
         ])
@@ -277,6 +279,7 @@ class TC_00_API_Misc(qubes.tests.QubesTestCase):
         self.assertIsNone(response)
         self.assertEqual(self.src.mock_calls, [])
         self.assertEqual(self.tpl.mock_calls, [
+            mock.call.updateable.__bool__(),
             mock.call.is_running(),
         ])
         self.assertIsInstance(self.tpl.updates_available, mock.Mock)
@@ -290,8 +293,29 @@ class TC_00_API_Misc(qubes.tests.QubesTestCase):
         self.assertIsNone(response)
         self.assertEqual(self.src.mock_calls, [])
         self.assertEqual(self.tpl.mock_calls, [
+            mock.call.updateable.__bool__(),
             mock.call.is_running(),
         ])
         self.assertIsInstance(self.src.updates_available, mock.Mock)
         self.assertEqual(self.app.mock_calls, [])
 
+    def test_028_notify_updates_template_based_dispvm(self):
+        self.dvm = self.src
+        self.dvm.updateable = False
+        self.srv = mock.NonCallableMagicMock(template=self.dvm)
+        self.src.updateable = False
+        self.src.template.is_running.return_value = False
+        self.src.storage.outdated_volumes = []
+        response = self.call_mgmt_func(b'qubes.NotifyUpdates', payload=b'1\n')
+        self.assertIsNone(response)
+        self.assertEqual(self.src.mock_calls, [])
+        self.assertEqual(self.dvm.mock_calls, [])
+        self.assertEqual(self.tpl.mock_calls, [
+            mock.call.updateable.__bool__(),
+            mock.call.is_running(),
+            mock.call.features.__setitem__('updates-available', True),
+        ])
+        self.assertIsInstance(self.src.updates_available, mock.Mock)
+        self.assertEqual(self.app.mock_calls, [
+            mock.call.save()
+        ])