Fixed bug #32282: TEXT silently truncates when value is exactly 65536

bytes length.

The server has been modified to report warnings on truncation to
65536 bytes as usual.



sql/sql_string.cc:
  Fixed bug #32282.
  The well_formed_copy_nchars function returned an incorrect value
  of copied bytes of the truncated input string: extra length of
  the first truncated character added to the *from_end_pos pointer.
  That has been fixed.
mysql-test/r/type_blob.result:
  Added test case for bug #32282.
mysql-test/t/type_blob.test:
  Added test case for bug #32282.

mysql-test/r/type_blob.result

@@ -807,4 +807,18 @@ set @@sql_mode='TRADITIONAL';
 create table t1 (a text default '');
 ERROR 42000: BLOB/TEXT column 'a' can't have a default value
 set @@sql_mode='';
+CREATE TABLE t (c TEXT CHARSET ASCII);
+INSERT INTO t (c) VALUES (REPEAT('1',65537));
+Warnings:
+Warning	1265	Data truncated for column 'c' at row 1
+INSERT INTO t (c) VALUES (REPEAT('2',65536));
+Warnings:
+Warning	1265	Data truncated for column 'c' at row 1
+INSERT INTO t (c) VALUES (REPEAT('3',65535));
+SELECT LENGTH(c), CHAR_LENGTH(c) FROM t;
+LENGTH(c)	CHAR_LENGTH(c)
+65535	65535
+65535	65535
+65535	65535
+DROP TABLE t;
 End of 5.0 tests

mysql-test/t/type_blob.test

@@ -436,4 +436,15 @@ set @@sql_mode='TRADITIONAL';
 create table t1 (a text default '');
 set @@sql_mode='';
 
+#
+# Bug #32282: TEXT silently truncates when value is exactly 65536 bytes
+#
+
+CREATE TABLE t (c TEXT CHARSET ASCII);
+INSERT INTO t (c) VALUES (REPEAT('1',65537));
+INSERT INTO t (c) VALUES (REPEAT('2',65536));
+INSERT INTO t (c) VALUES (REPEAT('3',65535));
+SELECT LENGTH(c), CHAR_LENGTH(c) FROM t;
+DROP TABLE t;
+
 --echo End of 5.0 tests

sql/sql_string.cc

@@ -858,7 +858,7 @@ outp:
   with optional left padding (for binary -> UCS2 conversion)
   
   SYNOPSIS
-    well_formed_copy_nhars()
+    well_formed_copy_nchars()
     to			     Store result here
     to_length                Maxinum length of "to" string
     to_cs		     Character set of "to" string
@@ -997,7 +997,10 @@ outp:
         goto outp;
       }
       else
+      {
+        from= from_prev;
         break;
+      }
     }
     *from_end_pos= from;
     res= to - to_start;