BUG#21143: mysqld hangs when using wrong number of subpartitions

Rewrote if-statement a bit shorter
Added check for subpartitions in REORGANIZE partitions to be of same number as
in base table.

mysql-test/r/partition_mgm.result

 DROP TABLE IF EXISTS t1;
+create table t1 (a int)
+partition by range (a)
+subpartition by key (a)
+(partition p0 values less than (10) (subpartition sp00, subpartition sp01),
+partition p1 values less than (20) (subpartition sp10, subpartition sp11));
+alter table t1 reorganize partition p0 into
+(partition p0 values less than (10) (subpartition sp00,
+subpartition sp01, subpartition sp02));
+ERROR HY000: Wrong number of subpartitions defined, mismatch with previous setting
+drop table t1;
 CREATE TABLE t1 (f_date DATE, f_varchar VARCHAR(30))
 PARTITION BY HASH(CAST(YEAR(f_date) AS SIGNED INTEGER)) PARTITIONS 2;
 SHOW CREATE TABLE t1;

mysql-test/t/partition_mgm.test

@@ -2,6 +2,23 @@
 --disable_warnings
 DROP TABLE IF EXISTS t1;
 --enable_warnings
+
+#
+# Bug 21143: mysqld hang when error in number of subparts in
+#            REORGANIZE command
+#
+create table t1 (a int)
+partition by range (a)
+subpartition by key (a)
+(partition p0 values less than (10) (subpartition sp00, subpartition sp01),
+ partition p1 values less than (20) (subpartition sp10, subpartition sp11));
+
+-- error ER_PARTITION_WRONG_NO_SUBPART_ERROR
+alter table t1 reorganize partition p0 into
+(partition p0 values less than (10) (subpartition sp00,
+subpartition sp01, subpartition sp02));
+drop table t1;
+ 
 CREATE TABLE t1 (f_date DATE, f_varchar VARCHAR(30))
 PARTITION BY HASH(CAST(YEAR(f_date) AS SIGNED INTEGER)) PARTITIONS 2;
 SHOW CREATE TABLE t1;

sql/ha_partition.cc

@@ -5145,13 +5145,12 @@ void ha_partition::print_error(int error, myf errflag)
   DBUG_ENTER("ha_partition::print_error");
 
   /* Should probably look for my own errors first */
-  /* monty: needs to be called for the last used partition ! */
   DBUG_PRINT("enter", ("error: %d", error));
 
   if (error == HA_ERR_NO_PARTITION_FOUND)
     m_part_info->print_no_partition_found(table);
   else
-    m_file[0]->print_error(error, errflag);
+    m_file[m_last_part]->print_error(error, errflag);
   DBUG_VOID_RETURN;
 }
 
@@ -5161,8 +5160,7 @@ bool ha_partition::get_error_message(int error, String *buf)
   DBUG_ENTER("ha_partition::get_error_message");
 
   /* Should probably look for my own errors first */
-  /* monty: needs to be called for the last used partition ! */
-  DBUG_RETURN(m_file[0]->get_error_message(error, buf));
+  DBUG_RETURN(m_file[m_last_part]->get_error_message(error, buf));
 }
 
 

sql/sql_partition.cc

@@ -3471,14 +3471,9 @@ bool mysql_unpack_partition(THD *thd, const uchar *part_buf,
   }
   table->part_info= part_info;
   table->file->set_part_info(part_info);
-  if (part_info->default_engine_type == NULL)
-  {
+  if (!part_info->default_engine_type)
     part_info->default_engine_type= default_db_type;
-  }
-  else
-  {
-    DBUG_ASSERT(part_info->default_engine_type == default_db_type);
-  }
+  DBUG_ASSERT(part_info->default_engine_type == default_db_type);
   part_info->item_free_list= thd->free_list;
 
   {
@@ -4392,6 +4387,13 @@ state of p1.
         my_error(ER_REORG_HASH_ONLY_ON_SAME_NO, MYF(0));
         DBUG_RETURN(TRUE);
       }
+      if (tab_part_info->is_sub_partitioned() &&
+          alt_part_info->no_subparts &&
+          alt_part_info->no_subparts != tab_part_info->no_subparts)
+      {
+        my_error(ER_PARTITION_WRONG_NO_SUBPART_ERROR, MYF(0));
+        DBUG_RETURN(TRUE);
+      }
       check_total_partitions= tab_part_info->no_parts + no_parts_new;
       check_total_partitions-= no_parts_reorged;
       if (check_total_partitions > MAX_PARTITIONS)