MDEV-6045 MySQL Bug#11829861 - SUBSTRING_INDEX() RESULTS "OMIT" CHARACTER WHEN USED INSIDE LOWER()

mysql-test/r/func_str.result

@@ -119,7 +119,7 @@ substring_index('aaaaaaaaa1','aaa',-3)
 aaaaaa1
 select substring_index('aaaaaaaaa1','aaa',-4);
 substring_index('aaaaaaaaa1','aaa',-4)
-
+aaaaaaaaa1
 select substring_index('the king of thethe hill','the',-2);
 substring_index('the king of thethe hill','the',-2)
 the hill
@@ -2657,3 +2657,32 @@ NULL	NULL
 8	
 drop table t1;
 End of 5.1 tests
+#
+# Start of 5.3 tests
+#
+#
+# Bug#11829861: SUBSTRING_INDEX() RESULTS IN MISSING CHARACTERS WHEN USED
+# INSIDE LOWER()
+#
+SET @user_at_host = 'root@mytinyhost-PC.local';
+SELECT LOWER(SUBSTRING_INDEX(@user_at_host, '@', -1));
+LOWER(SUBSTRING_INDEX(@user_at_host, '@', -1))
+mytinyhost-pc.local
+# End of test  BUG#11829861
+#
+# Bug#42404: SUBSTRING_INDEX() RESULTS ARE INCONSISTENT
+#
+CREATE TABLE t (i INT NOT NULL, c CHAR(255) NOT NULL);
+INSERT INTO t VALUES (0,'.www.mysql.com'),(1,'.wwwmysqlcom');
+SELECT i, SUBSTRING_INDEX(c, '.', -2) FROM t WHERE i = 1;
+i	SUBSTRING_INDEX(c, '.', -2)
+1	.wwwmysqlcom
+SELECT i, SUBSTRING_INDEX(c, '.', -2) FROM t;
+i	SUBSTRING_INDEX(c, '.', -2)
+0	mysql.com
+1	.wwwmysqlcom
+DROP TABLE t;
+# End of test  BUG#42404
+#
+# End of 5.3 tests
+#

mysql-test/t/func_str.test

@@ -1405,3 +1405,30 @@ select group_concat( i ), make_set( i, 'a', 'b' ) field from t1 group by field;
 drop table t1;
 
 --echo End of 5.1 tests
+
+--echo #
+--echo # Start of 5.3 tests
+--echo #
+
+--echo #
+--echo # Bug#11829861: SUBSTRING_INDEX() RESULTS IN MISSING CHARACTERS WHEN USED
+--echo # INSIDE LOWER()
+--echo #
+SET @user_at_host = 'root@mytinyhost-PC.local';
+SELECT LOWER(SUBSTRING_INDEX(@user_at_host, '@', -1));
+--echo # End of test  BUG#11829861
+
+--echo #
+--echo # Bug#42404: SUBSTRING_INDEX() RESULTS ARE INCONSISTENT
+--echo #
+
+CREATE TABLE t (i INT NOT NULL, c CHAR(255) NOT NULL);
+INSERT INTO t VALUES (0,'.www.mysql.com'),(1,'.wwwmysqlcom');
+SELECT i, SUBSTRING_INDEX(c, '.', -2) FROM t WHERE i = 1;
+SELECT i, SUBSTRING_INDEX(c, '.', -2) FROM t;
+DROP TABLE t;
+--echo # End of test  BUG#42404
+
+--echo #
+--echo # End of 5.3 tests
+--echo #

sql/item_strfunc.cc

@@ -1095,7 +1095,7 @@ String *Item_str_conv::val_str(String *str)
   if (multiply == 1)
   {
     uint len;
-    res= copy_if_not_alloced(str,res,res->length());
+    res= copy_if_not_alloced(&tmp_value, res, res->length());
     len= converter(collation.collation, (char*) res->ptr(), res->length(),
                                         (char*) res->ptr(), res->length());
     DBUG_ASSERT(len <= res->length());
@@ -1296,8 +1296,10 @@ void Item_func_substr_index::fix_length_and_dec()
 String *Item_func_substr_index::val_str(String *str)
 {
   DBUG_ASSERT(fixed == 1);
+  char buff[MAX_FIELD_WIDTH];
+  String tmp(buff,sizeof(buff),system_charset_info);
   String *res= args[0]->val_str(str);
-  String *delimiter= args[1]->val_str(&tmp_value);
+  String *delimiter= args[1]->val_str(&tmp);
   int32 count= (int32) args[2]->val_int();
   uint offset;