Bug#28846 Use of undocumented Prepared Statements crashes server

ALTER VIEW is currently not supported as a prepared statement
and should be disabled as such as they otherwise could cause server crashes.

ALTER VIEW is currently not supported when called from stored
procedures or functions for related reasons and should also be disabled.

This patch disables these DDL statements and adjusts the appropriate test
cases accordingly.

Additional tests has been added to reflect on the fact that we do support
CREATE/ALTER/DROP TABLE for Prepared Statements (PS), Stored Procedures (SP)
and PS within SP.


mysql-test/r/ps_1general.result:
  - Updated test to reflect on the new policy to disallow ALTER VIEW within SP.
mysql-test/r/sp-dynamic.result:
  - Added PS ALTER TABLE test from within SP-context to demonstrate that CREATE/ALTER/DROP
  TABLE statements is working.
  - Added PS CREATE/ALTER/DROP VIEW tests from within SP-context to show that
  ALTER VIEW is not supported, CREATE VIEW/DROP VIEW are supported.
mysql-test/r/sp-error.result:
  - Updated test to reflect on the new policy to disallow VIEW DDL within SP.
mysql-test/t/ps_1general.test:
  - Updated test to reflect on the new policy to disallow VIEW DDL within SP.
mysql-test/t/sp-dynamic.test:
  - Add PS ALTER TABLE test from within SP to demonstrate that CREATE/ALTER/DROP
  TABLE statements are supported.
mysql-test/t/sp-error.test:
  - Updated test to reflect on the new policy to disallow ALTER VIEW
  within SP-context.
  - Changed error code 1314 to the more abstract ER_SP_BADSTATEMENT.
sql/sql_class.h:
  - Added comment for clarity
sql/sql_parse.cc:
  - Added comment for clarity
sql/sql_prepare.cc:
  - Disallow ALTER VIEW as prepared statements until they are
    properly supported. Note that SQLCOM_CREATE_VIEW also handles ALTER VIEW
    statements.
sql/sql_view.cc:
  - converted to doxygen comments
  - Added comment for clarity
sql/sql_yacc.yy:
  - Disallow ALTER VIEW statements within a SP.
  If the parser is operating within the SP context, this is shown
  on the sp->sphead pointer. If this flag is set for view DDL operations
  we stop parsing with the error 'ER_SP_BAD_STATEMENT'.

1 files changed, 10 insertions, 2 deletions

diff --git a/mysql-test/t/sp-dynamic.test b/mysql-test/t/sp-dynamic.test
index 6546a5ab548..e6f4aae96ac 100644
--- a/mysql-test/t/sp-dynamic.test
+++ b/mysql-test/t/sp-dynamic.test
@@ -85,7 +85,7 @@ call p1()|
 call p1()|
 drop procedure p1|
 #
-# D. Create/Drop a table (a DDL that issues a commit) in Dynamic SQL.
+# D. Create/Drop/Alter a table (a DDL that issues a commit) in Dynamic SQL.
 # (should work ok).
 #
 create procedure p1()
@@ -96,6 +96,10 @@ begin
   execute stmt;
   insert into t1 (a) values (1);
   select * from t1;
+  prepare stmt_alter from "alter table t1 add (b int)";
+  execute stmt_alter;
+  insert into t1 (a,b) values (2,1);
+  deallocate prepare stmt_alter;
   deallocate prepare stmt;
   deallocate prepare stmt_drop;
 end|
@@ -239,6 +243,7 @@ drop procedure p1|
 # K. Use of continue handlers with Dynamic SQL.
 #
 drop table if exists t1|
+drop table if exists t2|
 create table t1 (id integer primary key auto_increment,
                  stmt_text char(35), status varchar(20))|
 insert into t1 (stmt_text) values
@@ -249,7 +254,10 @@ insert into t1 (stmt_text) values
   ("help help"), ("show databases"), ("show tables"),
   ("show table status"), ("show open tables"), ("show storage engines"),
   ("insert into t1 (id) values (1)"), ("update t1 set status=''"),
-  ("delete from t1"), ("truncate t1"), ("call p1()"), ("foo bar")|
+  ("delete from t1"), ("truncate t1"), ("call p1()"), ("foo bar"),
+  ("create view v1 as select 1"), ("alter view v1 as select 2"),
+  ("drop view v1"),("create table t2 (a int)"),("alter table t2 add (b int)"),
+  ("drop table t2")|
 create procedure p1()
 begin
   declare v_stmt_text varchar(255);