qubes/core2migration: rework load order

To successfully load all the data, proceed in order:
- set app.default_kernel
- load all templates
- set app.default_template
- load other VMs
- update network dependencies between VMs
- set other global properties

qubes/core2migration.py

@@ -60,11 +60,12 @@ class Core2Qubes(qubes.Qubes):
             raise ValueError("store path required")
         super(Core2Qubes, self).__init__(store, load, **kwargs)
 
-    def load_globals(self, element):
+    def load_default_template(self, element):
         default_template = element.get("default_template")
         self.default_template = int(default_template) \
             if default_template.lower() != "none" else None
 
+    def load_globals(self, element):
         default_netvm = element.get("default_netvm")
         if default_netvm is not None:
             self.default_netvm = int(default_netvm) \
@@ -85,7 +86,6 @@ class Core2Qubes(qubes.Qubes):
             self.clockvm = int(clockvm) \
                 if clockvm != "None" else None
 
-        self.default_kernel = element.get("default_kernel")
 
     def set_netvm_dependency(self, element):
         kwargs = {}
@@ -110,28 +110,8 @@ class Core2Qubes(qubes.Qubes):
 
         # TODO: dispvm_netvm
 
-    def load(self):
+    def import_core2_vm(self, element):
-        qubes_store_file = open(self._store, 'r')
+        vm_class_name = element.tag
-
-        try:
-            qubes_store_file.seek(0)
-            tree = lxml.etree.parse(qubes_store_file)
-        except (EnvironmentError,
-                xml.parsers.expat.ExpatError) as err:
-            self.log.error(err)
-            return False
-
-        self.load_initial_values()
-
-
-        vm_classes = ["TemplateVm", "TemplateHVm",
-            "AppVm", "HVm", "NetVm", "ProxyVm"]
-        for (vm_class_name) in vm_classes:
-            vms_of_class = tree.findall("Qubes" + vm_class_name)
-            # first non-template based, then template based
-            sorted_vms_of_class = sorted(vms_of_class,
-                key=lambda x: str(x.get('template_qid')).lower() != "none")
-            for element in sorted_vms_of_class:
         try:
             kwargs = {}
             if vm_class_name in ["TemplateVm", "TemplateHVm"]:
@@ -196,6 +176,41 @@ class Core2Qubes(qubes.Qubes):
             if 'vm' in locals():
                 del self.domains[vm]
 
+    def load(self):
+        qubes_store_file = open(self._store, 'r')
+
+        try:
+            qubes_store_file.seek(0)
+            tree = lxml.etree.parse(qubes_store_file)
+        except (EnvironmentError,
+                xml.parsers.expat.ExpatError) as err:
+            self.log.error(err)
+            return False
+
+        self.load_initial_values()
+
+        self.default_kernel = tree.getroot().get("default_kernel")
+
+        vm_classes = ["TemplateVm", "TemplateHVm",
+            "AppVm", "HVm", "NetVm", "ProxyVm"]
+        # First load templates
+        for vm_class_name in ["TemplateVm", "TemplateHVm"]:
+            vms_of_class = tree.findall("Qubes" + vm_class_name)
+            for element in vms_of_class:
+                self.import_core2_vm(element)
+
+        # Then set default template ...
+        self.load_default_template(tree.getroot())
+
+        # ... and load other VMs
+        for vm_class_name in ["AppVm", "HVm", "NetVm", "ProxyVm"]:
+            vms_of_class = tree.findall("Qubes" + vm_class_name)
+            # first non-template based, then template based
+            sorted_vms_of_class = sorted(vms_of_class,
+                key=lambda x: str(x.get('template_qid')).lower() != "none")
+            for element in sorted_vms_of_class:
+                self.import_core2_vm(element)
+
         # After importing all VMs, set netvm references, in the same order
         for vm_class_name in vm_classes:
             for element in tree.findall("Qubes" + vm_class_name):
@@ -205,6 +220,7 @@ class Core2Qubes(qubes.Qubes):
                     self.log.error("VM {}: failed to set netvm dependency: {}".
                         format(element.get('name'), err))
 
+        # and load other defaults (default netvm, updatevm etc)
         self.load_globals(tree.getroot())
 
     def save(self):