Add supervisor:get_callback_module/1

This function is used by release_handler during upgrade. This was
earlier implemented in the release_handler, but it required a copy og
the definition of the supervisor's internal state, which caused
problems when this state was updated.

1 files changed, 14 insertions, 0 deletions

diff --git a/lib/stdlib/src/supervisor.erl b/lib/stdlib/src/supervisor.erl
index 92a0c29011..6a5005b4b6 100644
--- a/lib/stdlib/src/supervisor.erl
+++ b/lib/stdlib/src/supervisor.erl
@@ -33,6 +33,9 @@
 	 terminate/2, code_change/3]).
 -export([try_again_restart/2]).
 
+%% For release_handler only
+-export([get_callback_module/1]).
+
 %%--------------------------------------------------------------------------
 
 -export_type([sup_flags/0, child_spec/0, startchild_ret/0, strategy/0]).
@@ -250,6 +253,17 @@ try_again_restart(Supervisor, Child) ->
 cast(Supervisor, Req) ->
     gen_server:cast(Supervisor, Req).
 
+%%%-----------------------------------------------------------------
+%%% Called by release_handler during upgrade
+-spec get_callback_module(Pid) -> Module when
+      Pid :: pid(),
+      Module :: atom().
+get_callback_module(Pid) ->
+    {status, _Pid, {module, _Mod},
+     [_PDict, _SysState, _Parent, _Dbg, Misc]} = sys:get_status(Pid),
+    [_Header, _Data, {data, [{"State", State}]}] = Misc,
+    State#state.module.
+
 %%% ---------------------------------------------------
 %%% 
 %%% Initialize the supervisor.