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().

2 files changed, 39 insertions, 0 deletions

diff --git a/mysql-test/r/ps.result b/mysql-test/r/ps.result
index 2be5366b180..01aa4ddf859 100644
--- a/mysql-test/r/ps.result
+++ b/mysql-test/r/ps.result
@@ -875,3 +875,17 @@ select @@max_prepared_stmt_count, @@prepared_stmt_count;
 @@max_prepared_stmt_count	@@prepared_stmt_count
 3	0
 set global max_prepared_stmt_count= @old_max_prepared_stmt_count;
+drop table if exists t1;
+create temporary table if not exists t1 (a1 int);
+prepare stmt from "delete t1 from t1 where (cast(a1/3 as unsigned) * 3) = a1";
+drop temporary table t1;
+create temporary table if not exists t1 (a1 int);
+execute stmt;
+drop temporary table t1;
+create temporary table if not exists t1 (a1 int);
+execute stmt;
+drop temporary table t1;
+create temporary table if not exists t1 (a1 int);
+execute stmt;
+drop temporary table t1;
+deallocate prepare stmt;
diff --git a/mysql-test/t/ps.test b/mysql-test/t/ps.test
index d6dcf02d5b7..0ca293eb1ba 100644
--- a/mysql-test/t/ps.test
+++ b/mysql-test/t/ps.test
@@ -926,4 +926,29 @@ select @@max_prepared_stmt_count, @@prepared_stmt_count;
 set global max_prepared_stmt_count= @old_max_prepared_stmt_count;
 --enable_ps_protocol
 
+#
+# Bug#19399 "Stored Procedures 'Lost Connection' when dropping/creating
+#            tables"
+# Check that multi-delete tables are also cleaned up before re-execution.
+# 
+--disable_warnings
+drop table if exists t1;
+create temporary table if not exists t1 (a1 int);
+--enable_warnings
+# exact delete syntax is essential
+prepare stmt from "delete t1 from t1 where (cast(a1/3 as unsigned) * 3) = a1";
+drop temporary table t1;
+create temporary table if not exists t1 (a1 int);
+# the server crashed on  the next statement without the fix
+execute stmt;
+drop temporary table t1;
+create temporary table if not exists t1 (a1 int);
+# the problem was in memory corruption: repeat the test just in case
+execute stmt;
+drop temporary table t1;
+create temporary table if not exists t1 (a1 int);
+execute stmt;
+drop temporary table t1;
+deallocate prepare stmt;
+
 # End of 4.1 tests