A fix and a test case for Bug#19399 "res 'Lost Connection' when

dropping/creating tables".

The bug could lead to a crash when multi-delete statements were
prepared and used with temporary tables.

The bug was caused by lack of clean-up of multi-delete tables before
re-execution of a prepared statement. In a statement like
DELETE t1 FROM t1, t2 WHERE ... the first table list (t1) is
moved to lex->auxilliary_table_list and excluded from lex->query_tables
or select_lex->tables. Thus it was unaccessible to reinit_stmt_before_use
and not cleaned up before re-execution of a prepared statement. 


mysql-test/r/ps.result:
  Updated test results (Bug#19399)
mysql-test/t/ps.test:
  A test case for Bug#19399 "Stored Procedures 'Lost Connection' when 
  dropping/creating tables": test that multi-delete
  tables are cleaned up properly before re-execution.
sql/sql_lex.cc:
  Always initialize auxilliary_table_list when we initialize the lex:
  this way we don't have to check that lex->sql_command equals to
  SQLCOM_DELETE_MULTI whenever we need to access auxilliary_table_list.
  In particular, in reinit_stmt_before_use we can simply check that
  auxilliary_table_list is not NULL and clean it up if the check returns
  a true value.
sql/sql_prepare.cc:
  Move the one table clean-up functionality to a method of st_table_list.
  Clean up auxiliary_table_list if it's not empty.
sql/table.cc:
  Implement st_table_list::reinit_before_use().
sql/table.h:
  Declare st_table_list::reinit_before_use().

1 files changed, 1 insertions, 0 deletions

diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index 29ea8ab2ae2..fb9a765f12c 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -125,6 +125,7 @@ void lex_start(THD *thd, uchar *buf,uint length)
   lex->value_list.empty();
   lex->update_list.empty();
   lex->param_list.empty();
+  lex->auxilliary_table_list.empty();
   lex->unit.next= lex->unit.master=
     lex->unit.link_next= lex->unit.return_to= 0;
   lex->unit.prev= lex->unit.link_prev= 0;