Implement WL#2661 "Prepared Statements: Dynamic SQL in Stored Procedures".

The idea of the patch is to separate statement processing logic,
such as parsing, validation of the parsed tree, execution and cleanup, 
from global query processing logic, such as logging, resetting
priorities of a thread, resetting stored procedure cache, resetting
thread count of errors and warnings.
This makes PREPARE and EXECUTE behave similarly to the rest of SQL
statements and allows their use in stored procedures.
This patch contains a change in behaviour:
until recently for each SQL prepared statement command, 2 queries
were written to the general log, e.g.
[Query]   prepare stmt from @stmt_text;
[Prepare] select * from t1 <-- contents of @stmt_text
The chagne was necessary to prevent [Prepare] commands from being written
to the general log when executing a stored procedure with Dynamic SQL.
We should consider whether the old behavior is preferrable and probably
restore it.
This patch refixes Bug#7115, Bug#10975 (partially), Bug#10605 (various bugs
in Dynamic SQL reported before it was disabled).

1 files changed, 24 insertions, 9 deletions

diff --git a/sql/sp_head.h b/sql/sp_head.h
index 1d4bfb514d3..1c54b1a567d 100644
--- a/sql/sp_head.h
+++ b/sql/sp_head.h
@@ -33,8 +33,8 @@
 Item_result
 sp_map_result_type(enum enum_field_types type);
 
-bool
-sp_multi_results_command(enum enum_sql_command cmd);
+uint
+sp_get_flags_for_command(LEX *lex);
 
 struct sp_label;
 class sp_instr;
@@ -107,18 +107,23 @@ class sp_head :private Query_arena
 
   MEM_ROOT main_mem_root;
 public:
+  /* Possible values of m_flags */
+  const static int
+    HAS_RETURN= 1,              // For FUNCTIONs only: is set if has RETURN
+    IN_SIMPLE_CASE= 2,          // Is set if parsing a simple CASE
+    IN_HANDLER= 4,              // Is set if the parser is in a handler body
+    MULTI_RESULTS= 8,           // Is set if a procedure with SELECT(s)
+    CONTAINS_DYNAMIC_SQL= 16,   // Is set if a procedure with PREPARE/EXECUTE
+    IS_INVOKED= 32;             // Is set if this sp_head is being used.
 
   int m_type;			// TYPE_ENUM_FUNCTION or TYPE_ENUM_PROCEDURE
+  uint m_flags;                 // Boolean attributes of a stored routine
   enum enum_field_types m_returns; // For FUNCTIONs only
   Field::geometry_type m_geom_returns;
   CHARSET_INFO *m_returns_cs;	// For FUNCTIONs only
   TYPELIB *m_returns_typelib;	// For FUNCTIONs only
   uint m_returns_len;		// For FUNCTIONs only
   uint m_returns_pack;		// For FUNCTIONs only
-  my_bool m_has_return;		// For FUNCTIONs only
-  my_bool m_simple_case;	// TRUE if parsing simple case, FALSE otherwise
-  my_bool m_multi_results;	// TRUE if a procedure with SELECT(s)
-  my_bool m_in_handler;		// TRUE if parser in a handler body
   uchar *m_tmp_query;		// Temporary pointer to sub query string
   uint m_old_cmq;		// Old CLIENT_MULTI_QUERIES value
   st_sp_chistics *m_chistics;
@@ -265,6 +270,19 @@ public:
   bool add_used_tables_to_table_list(THD *thd,
                                      TABLE_LIST ***query_tables_last_ptr);
 
+  /*
+    Check if this stored routine contains statements disallowed
+    in a stored function or trigger, and set an appropriate error message
+    if this is the case.
+  */
+  bool is_not_allowed_in_function(const char *where)
+  {
+    if (m_flags & CONTAINS_DYNAMIC_SQL)
+      my_error(ER_STMT_NOT_ALLOWED_IN_SF_OR_TRG, MYF(0), "Dynamic SQL");
+    else if (m_flags & MULTI_RESULTS)
+      my_error(ER_SP_NO_RETSET, MYF(0), where);
+    return test(m_flags & (CONTAINS_DYNAMIC_SQL|MULTI_RESULTS));
+  }
 private:
 
   MEM_ROOT *m_thd_root;		// Temp. store for thd's mem_root
@@ -290,9 +308,6 @@ private:
   */
   HASH m_sptabs;
 
-  /* Used for tracking of routine invocations and preventing recursion. */
-  bool m_is_invoked;
-
   int
   execute(THD *thd);