Bug#16172 DECIMAL data type processed incorrectly

issue an 'overflow warning' if result value is bigger than max possible value

3 files changed, 32 insertions, 1 deletions

diff --git a/sql/item_create.cc b/sql/item_create.cc
index 7147142d8a7..e02ba384717 100644
--- a/sql/item_create.cc
+++ b/sql/item_create.cc
@@ -463,7 +463,7 @@ Item *create_func_cast(Item *a, Cast_target cast_type, int len, int dec,
   case ITEM_CAST_TIME:		res= new Item_time_typecast(a); break;
   case ITEM_CAST_DATETIME:	res= new Item_datetime_typecast(a); break;
   case ITEM_CAST_DECIMAL:
-    res= new Item_decimal_typecast(a, (len>0) ? len : 10, dec ? dec : 2);
+    res= new Item_decimal_typecast(a, (len > 0) ? len : 10, dec);
     break;
   case ITEM_CAST_CHAR:
     res= new Item_char_typecast(a, len, cs ? cs : 
diff --git a/sql/item_func.cc b/sql/item_func.cc
index e901eaf8654..250dec6ae57 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -955,9 +955,32 @@ longlong Item_decimal_typecast::val_int()
 my_decimal *Item_decimal_typecast::val_decimal(my_decimal *dec)
 {
   my_decimal tmp_buf, *tmp= args[0]->val_decimal(&tmp_buf);
+  bool sign;
   if ((null_value= args[0]->null_value))
     return NULL;
   my_decimal_round(E_DEC_FATAL_ERROR, tmp, decimals, FALSE, dec);
+  sign= dec->sign();
+  if (unsigned_flag)
+  {
+    if (sign)
+    {
+      my_decimal_set_zero(dec);
+      goto err;
+    }
+  }
+  if (max_length - 2 - decimals < (uint) my_decimal_intg(dec))
+  {
+    max_my_decimal(dec, max_length - 2, decimals);
+    dec->sign(sign);
+    goto err;
+  }
+  return dec;
+
+err:
+  push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_ERROR,
+                      ER_WARN_DATA_OUT_OF_RANGE,
+                      ER(ER_WARN_DATA_OUT_OF_RANGE),
+                      name, 1);
   return dec;
 }
 
diff --git a/sql/my_decimal.h b/sql/my_decimal.h
index b02abacf0a3..3ce8cfee75d 100644
--- a/sql/my_decimal.h
+++ b/sql/my_decimal.h
@@ -383,5 +383,13 @@ int my_decimal_cmp(const my_decimal *a, const my_decimal *b)
   return decimal_cmp((decimal_t*) a, (decimal_t*) b);
 }
 
+
+inline
+int my_decimal_intg(const my_decimal *a)
+{
+  return decimal_intg((decimal_t*) a);
+}
+
+
 #endif /*my_decimal_h*/