sharing: add hook for simple calls

radicale/app/mkcol.py

@@ -61,6 +61,13 @@ class ApplicationPartMkcol(ApplicationBase):
         if not props.get("tag") and "W" not in permissions:
             logger.warning("MKCOL request %r (type:%s): %s", path, collection_type, "rejected because of missing rights 'W'")
             return httputils.NOT_ALLOWED
+        if self._sharing._enabled:
+            # check for shared collections (active or inactive)
+            collections_shared_map = self._sharing.sharing_collection_map_list(user, active=False)
+            if collections_shared_map:
+                for sharing in collections_shared_map:
+                    if sharing['PathOrToken'] == path:
+                        return httputils.CONFLICT
         with self._storage.acquire_lock("w", user, path=path, request="MKCOL"):
             item = next(iter(self._storage.discover(path)), None)
             if item: