GBAK does not initialize RDB$RETURN_ARGUMENT, RDB$ARGUMENT_POSITION fields and can write unexpected values into restored database when backup does not have data for ones.

See these two functions:

1. get_function
   

   firebird/src/burp/restore.epp

   Line 4947 in cf98c6e

   bool get_function(BurpGlobals* tdgbl)

2. get_function_arg
   

   firebird/src/burp/restore.epp

   Line 5333 in cf98c6e

   void get_function_arg(BurpGlobals* tdgbl, bool skip_arguments)

I offer to add the initialization of these fields with NULL value.