Fix Bug#11333 "Stored Procedure: Memory blow up on repeated SELECT ... INTO query"

mysql-test/r/sp.result:
  update result
mysql-test/t/sp.test:
  Add test for Bug #11333 "Stored Procedure: Memory blow up on repeated SELECT ... INTO query"
sql/item.cc:
  we should call destructors for Items before reuse
sql/item.h:
  Add new method and constructor for Item_string.
sql/sp_head.cc:
  String allocation should be done on the system heap for now.

1 files changed, 18 insertions, 0 deletions

diff --git a/sql/item.h b/sql/item.h
index 4dfd99e0dbd..51f7c641de1 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -1298,6 +1298,15 @@ public:
     // it is constant => can be used without fix_fields (and frequently used)
     fixed= 1;
   }
+  /* Just create an item and do not fill string representation */
+  Item_string(CHARSET_INFO *cs, Derivation dv= DERIVATION_COERCIBLE)
+  {
+    collation.set(cs, dv);
+    max_length= 0;
+    set_name(NULL, 0, cs);
+    decimals= NOT_FIXED_DEC;
+    fixed= 1;
+  }
   Item_string(const char *name_par, const char *str, uint length,
 	      CHARSET_INFO *cs, Derivation dv= DERIVATION_COERCIBLE)
   {
@@ -1309,6 +1318,15 @@ public:
     // it is constant => can be used without fix_fields (and frequently used)
     fixed= 1;
   }
+  /*
+    This is used in stored procedures to avoid memory leaks and
+    does a deep copy of its argument.
+  */
+  void set_str_with_copy(const char *str_arg, uint length_arg)
+  {
+    str_value.copy(str_arg, length_arg, collation.collation);
+    max_length= str_value.numchars() * collation.collation->mbmaxlen;
+  }
   enum Type type() const { return STRING_ITEM; }
   double val_real();
   longlong val_int();