bug#10344: some string function fail for UCS2

substr fix

mysql-test/r/ctype_ucs.result

@@ -598,6 +598,24 @@ ucs2_bin	00610009
 ucs2_bin	0061
 ucs2_bin	00610020
 drop table t1;
+select hex(substr(_ucs2 0x00e400e50068,1));
+hex(substr(_ucs2 0x00e400e50068,1))
+00E400E50068
+select hex(substr(_ucs2 0x00e400e50068,2));
+hex(substr(_ucs2 0x00e400e50068,2))
+00E50068
+select hex(substr(_ucs2 0x00e400e50068,3));
+hex(substr(_ucs2 0x00e400e50068,3))
+0068
+select hex(substr(_ucs2 0x00e400e50068,-1));
+hex(substr(_ucs2 0x00e400e50068,-1))
+0068
+select hex(substr(_ucs2 0x00e400e50068,-2));
+hex(substr(_ucs2 0x00e400e50068,-2))
+00E50068
+select hex(substr(_ucs2 0x00e400e50068,-3));
+hex(substr(_ucs2 0x00e400e50068,-3))
+00E400E50068
 SET NAMES latin1;
 SET collation_connection='ucs2_swedish_ci';
 CREATE TABLE t1 (Field1 int(10) default '0');

mysql-test/t/ctype_ucs.test

@@ -374,6 +374,16 @@ SET NAMES latin1;
 SET collation_connection='ucs2_bin';
 -- source include/ctype_filesort.inc
 
+#
+# Bug#10344 Some string functions fail for UCS2
+#
+select hex(substr(_ucs2 0x00e400e50068,1));
+select hex(substr(_ucs2 0x00e400e50068,2));
+select hex(substr(_ucs2 0x00e400e50068,3));
+select hex(substr(_ucs2 0x00e400e50068,-1));
+select hex(substr(_ucs2 0x00e400e50068,-2));
+select hex(substr(_ucs2 0x00e400e50068,-3));
+
 SET NAMES latin1;
 #
 # Bug#8235

strings/ctype-ucs2.c

@@ -1261,7 +1261,7 @@ uint my_charpos_ucs2(CHARSET_INFO *cs __attribute__((unused)),
 		     const char *e  __attribute__((unused)),
 		     uint pos)
 {
-  return pos*2;
+  return pos > e - b ? e - b + 2 : pos * 2;
 }