Disallow to modify a template if changes cannot be written on disk. Fixes #1695

gns3server/controller/__init__.py

@@ -132,6 +132,20 @@ class Controller:
         self._computes = {}
         self._projects = {}
 
+    def check_can_write_config(self):
+        """
+        Check if the controller configuration can be written on disk
+
+        :returns: boolean
+        """
+
+        try:
+            os.makedirs(os.path.dirname(self._config_file), exist_ok=True)
+            if not os.access(self._config_file, os.W_OK):
+                raise aiohttp.web.HTTPConflict(text="Change rejected, cannot write to controller configuration file '{}'".format(self._config_file))
+        except OSError as e:
+            raise aiohttp.web.HTTPConflict(text="Change rejected: {}".format(e))
+
     def save(self):
         """
         Save the controller configuration on disk

gns3server/controller/template.py

@@ -177,9 +177,11 @@ class Template:
 
     def update(self, **kwargs):
 
-        self._settings.update(kwargs)
+
         from gns3server.controller import Controller
         controller = Controller.instance()
+        Controller.instance().check_can_write_config()
+        self._settings.update(kwargs)
         controller.notification.controller_emit("template.updated", self.__json__())
         controller.save()
 

gns3server/controller/template_manager.py

@@ -93,8 +93,10 @@ class TemplateManager:
         except jsonschema.ValidationError as e:
             message = "JSON schema error adding template with JSON data '{}': {}".format(settings, e.message)
             raise aiohttp.web.HTTPBadRequest(text=message)
-        self._templates[template.id] = template
+
         from . import Controller
+        Controller.instance().check_can_write_config()
+        self._templates[template.id] = template
         Controller.instance().save()
         Controller.instance().notification.controller_emit("template.created", template.__json__())
         return template
@@ -123,8 +125,9 @@ class TemplateManager:
         template = self.get_template(template_id)
         if template.builtin:
             raise aiohttp.web.HTTPConflict(text="Template ID {} cannot be deleted because it is a builtin".format(template_id))
-        self._templates.pop(template_id)
         from . import Controller
+        Controller.instance().check_can_write_config()
+        self._templates.pop(template_id)
         Controller.instance().save()
         Controller.instance().notification.controller_emit("template.deleted", template.__json__())