Bug#28878: InnoDB tables with UTF8 character set and indexes cause

wrong result for DML
When making key reference buffers over CHAR fields whitespace (0x20) 
must be used to fill in the remaining space in the field's buffer.
This is what Field_string::store() does.
Fixed Field_string::get_key_image() to do the same.

mysql-test/r/innodb_mysql.result

@@ -617,4 +617,40 @@ EXPLAIN SELECT COUNT(*) FROM t2 WHERE stat_id IN (1,3) AND acct_id=785;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	range	idx1,idx2	idx1	9	NULL	2	Using where; Using index
 DROP TABLE t1,t2;
+CREATE TABLE t1 (a CHAR(2), KEY (a)) ENGINE = InnoDB DEFAULT CHARSET=UTF8;
+INSERT INTO t1 VALUES ('uk'),('bg');
+SELECT * FROM t1 WHERE a = 'uk';
+a
+uk
+DELETE FROM t1 WHERE a = 'uk';
+SELECT * FROM t1 WHERE a = 'uk';
+a
+UPDATE t1 SET a = 'us' WHERE a = 'uk';
+SELECT * FROM t1 WHERE a = 'uk';
+a
+CREATE TABLE t2 (a CHAR(2), KEY (a)) ENGINE = InnoDB;
+INSERT INTO t2 VALUES ('uk'),('bg');
+SELECT * FROM t2 WHERE a = 'uk';
+a
+uk
+DELETE FROM t2 WHERE a = 'uk';
+SELECT * FROM t2 WHERE a = 'uk';
+a
+INSERT INTO t2 VALUES ('uk');
+UPDATE t2 SET a = 'us' WHERE a = 'uk';
+SELECT * FROM t2 WHERE a = 'uk';
+a
+CREATE TABLE t3 (a CHAR(2), KEY (a)) ENGINE = MyISAM;
+INSERT INTO t3 VALUES ('uk'),('bg');
+SELECT * FROM t3 WHERE a = 'uk';
+a
+uk
+DELETE FROM t3 WHERE a = 'uk';
+SELECT * FROM t3 WHERE a = 'uk';
+a
+INSERT INTO t3 VALUES ('uk');
+UPDATE t3 SET a = 'us' WHERE a = 'uk';
+SELECT * FROM t3 WHERE a = 'uk';
+a
+DROP TABLE t1,t2,t3;
 End of 5.0 tests

mysql-test/t/innodb_mysql.test

@@ -597,4 +597,35 @@ EXPLAIN SELECT COUNT(*) FROM t2 WHERE stat_id IN (1,3) AND acct_id=785;
 
 DROP TABLE t1,t2; 
 
+#
+# Bug #25866: Getting "#HY000 Can't find record in..." on and INSERT
+#
+CREATE TABLE t1 (a CHAR(2), KEY (a)) ENGINE = InnoDB DEFAULT CHARSET=UTF8;
+INSERT INTO t1 VALUES ('uk'),('bg');
+SELECT * FROM t1 WHERE a = 'uk';
+DELETE FROM t1 WHERE a = 'uk';
+SELECT * FROM t1 WHERE a = 'uk';
+UPDATE t1 SET a = 'us' WHERE a = 'uk';
+SELECT * FROM t1 WHERE a = 'uk';
+
+CREATE TABLE t2 (a CHAR(2), KEY (a)) ENGINE = InnoDB;
+INSERT INTO t2 VALUES ('uk'),('bg');
+SELECT * FROM t2 WHERE a = 'uk';
+DELETE FROM t2 WHERE a = 'uk';
+SELECT * FROM t2 WHERE a = 'uk';
+INSERT INTO t2 VALUES ('uk');
+UPDATE t2 SET a = 'us' WHERE a = 'uk';
+SELECT * FROM t2 WHERE a = 'uk';
+
+CREATE TABLE t3 (a CHAR(2), KEY (a)) ENGINE = MyISAM;
+INSERT INTO t3 VALUES ('uk'),('bg');
+SELECT * FROM t3 WHERE a = 'uk';
+DELETE FROM t3 WHERE a = 'uk';
+SELECT * FROM t3 WHERE a = 'uk';
+INSERT INTO t3 VALUES ('uk');
+UPDATE t3 SET a = 'us' WHERE a = 'uk';
+SELECT * FROM t3 WHERE a = 'uk';
+
+DROP TABLE t1,t2,t3;
+
 --echo End of 5.0 tests

sql/field.cc

@@ -6249,7 +6249,8 @@ uint Field_string::get_key_image(char *buff, uint length, imagetype type_arg)
                           length / field_charset->mbmaxlen);
   memcpy(buff, ptr, bytes);
   if (bytes < length)
-    bzero(buff + bytes, length - bytes);
+    field_charset->cset->fill(field_charset, buff + bytes, length - bytes, 
+                              field_charset->pad_char);
   return bytes;
 }