Transfer power level state events on room upgrade (#6237)

* commit '72078e4be':
  Transfer power level state events on room upgrade (#6237)

changelog.d/6237.bugfix

@@ -0,0 +1 @@
+Transfer non-standard power levels on room upgrade.

synapse/handlers/room.py

@@ -200,21 +200,21 @@ def _upgrade_room(self, requester, old_room_id, new_version):
  # finally, shut down the PLs in the old room, and update them in the new
  # room.
  yield self._update_upgraded_room_pls(
- requester, old_room_id, new_room_id, old_room_state
+ requester, old_room_id, new_room_id, old_room_state,
  )
 
  return new_room_id
 
  @defer.inlineCallbacks
  def _update_upgraded_room_pls(
- self, requester, old_room_id, new_room_id, old_room_state
+ self, requester, old_room_id, new_room_id, old_room_state,
  ):
  """Send updated power levels in both rooms after an upgrade
 
  Args:
  requester (synapse.types.Requester): the user requesting the upgrade
- old_room_id (unicode): the id of the room to be replaced
- new_room_id (unicode): the id of the replacement room
+ old_room_id (str): the id of the room to be replaced
+ new_room_id (str): the id of the replacement room
  old_room_state (dict[tuple[str, str], str]): the state map for the old room
 
  Returns:
@@ -300,7 +300,7 @@ def clone_existing_room(
  tombstone_event_id (unicode|str): the ID of the tombstone event in the old
  room.
  Returns:
- Deferred[None]
+ Deferred
  """
  user_id = requester.user.to_string()
 
@@ -347,6 +347,7 @@ def clone_existing_room(
  (EventTypes.Encryption, ""),
  (EventTypes.ServerACL, ""),
  (EventTypes.RelatedGroups, ""),
+ (EventTypes.PowerLevels, ""),
  )
 
  old_room_state_ids = yield self.store.get_filtered_current_state_ids(
@@ -360,6 +361,31 @@ def clone_existing_room(
  if old_event:
  initial_state[k] = old_event.content
 
+ # Resolve the minimum power level required to send any state event
+ # We will give the upgrading user this power level temporarily (if necessary) such that
+ # they are able to copy all of the state events over, then revert them back to their
+ # original power level afterwards in _update_upgraded_room_pls
+
+ # Copy over user power levels now as this will not be possible with >100PL users once
+ # the room has been created
+
+ power_levels = initial_state[(EventTypes.PowerLevels, "")]
+
+ # Calculate the minimum power level needed to clone the room
+ event_power_levels = power_levels.get("events", {})
+ state_default = power_levels.get("state_default", 0)
+ ban = power_levels.get("ban")
+ needed_power_level = max(state_default, ban, max(event_power_levels.values()))
+
+ # Raise the requester's power level in the new room if necessary
+ current_power_level = power_levels["users"][requester.user.to_string()]
+ if current_power_level < needed_power_level:
+ # Assign this power level to the requester
+ power_levels["users"][requester.user.to_string()] = needed_power_level
+
+ # Set the power levels to the modified state
+ initial_state[(EventTypes.PowerLevels, "")] = power_levels
+
  yield self._send_events_for_new_room(
  requester,
  new_room_id,