Merge branch 'mysql-5.5' into mysql-5.6

Sreeharsha Ramanavarapu · Sreeharsha Ramanavarapu · commit 9c1d12e42a9b · 2015-07-16T07:57:53.000+05:30
diff --git a/mysql-test/r/update.result b/mysql-test/r/update.result
@@ -593,3 +593,16 @@ Variable_name	Value
 Handler_update	5
 ROLLBACK;
 DROP TABLE t1, t2;
+# Bug #21143080: UPDATE ON VARCHAR AND TEXT COLUMNS PRODUCE INCORRECT
+#                RESULTS
+CREATE TABLE t1 (a VARCHAR(50), b TEXT, c CHAR(50)) ENGINE=INNODB;
+INSERT INTO t1 (a, b, c) VALUES ('start trail', '', 'even longer string');
+UPDATE t1 SET b = a, a = 'inject';
+SELECT a, b FROM t1;
+a	b
+inject	start trail
+UPDATE t1 SET b = c, c = 'inject';
+SELECT c, b FROM t1;
+c	b
+inject	even longer string
+DROP TABLE t1;
diff --git a/mysql-test/t/update.test b/mysql-test/t/update.test
@@ -541,3 +541,16 @@ UPDATE t2 SET c = 10 ORDER BY a, b DESC LIMIT 5;
 SHOW STATUS LIKE 'HANDLER_UPDATE';
 ROLLBACK;
 DROP TABLE t1, t2;
+
+--echo # Bug #21143080: UPDATE ON VARCHAR AND TEXT COLUMNS PRODUCE INCORRECT
+--echo #                RESULTS
+
+CREATE TABLE t1 (a VARCHAR(50), b TEXT, c CHAR(50)) ENGINE=INNODB;
+
+INSERT INTO t1 (a, b, c) VALUES ('start trail', '', 'even longer string');
+UPDATE t1 SET b = a, a = 'inject';
+SELECT a, b FROM t1;
+UPDATE t1 SET b = c, c = 'inject';
+SELECT c, b FROM t1;
+
+DROP TABLE t1;
diff --git a/sql/field.h b/sql/field.h
@@ -1,7 +1,7 @@
 #ifndef FIELD_INCLUDED
 #define FIELD_INCLUDED
 
-/* Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -1236,6 +1236,17 @@ class Field
 
   /* Hash value */
   virtual void hash(ulong *nr, ulong *nr2);
+
+/**
+  Checks whether a string field is part of write_set.
+
+  @return
+    FALSE  - If field is not char/varchar/....
+           - If field is char/varchar/.. and is not part of write set.
+    TRUE   - If field is char/varchar/.. and is part of write set.
+*/
+  virtual bool is_updatable() const { return FALSE; }
+
   friend int cre_myisam(char * name, register TABLE *form, uint options,
 			ulonglong auto_increment_value);
   friend class Copy_field;
@@ -1523,6 +1534,11 @@ class Field_longstr :public Field_str
 
   type_conversion_status store_decimal(const my_decimal *d);
   uint32 max_data_length() const;
+  bool is_updatable() const
+  {
+    DBUG_ASSERT(table && table->write_set);
+    return bitmap_is_set(table->write_set, field_index);
+  }
 };
 
 /* base class for float and double and decimal (old one) */
diff --git a/sql/field_conv.cc b/sql/field_conv.cc
@@ -1,4 +1,4 @@
-/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -826,15 +826,10 @@ type_conversion_status field_conv(Field *to,Field *from)
   {						// Be sure the value is stored
     Field_blob *blob=(Field_blob*) to;
     from->val_str(&blob->value);
-    /*
-      Copy value if copy_blobs is set, or source is not a string and
-      we have a pointer to its internal string conversion buffer.
-    */
-    if (to->table->copy_blobs ||
-        (!blob->value.is_alloced() &&
-         from->real_type() != MYSQL_TYPE_STRING &&
-         from->real_type() != MYSQL_TYPE_VARCHAR))
+
+    if (!blob->value.is_alloced() && from->is_updatable())
       blob->value.copy();
+
     return blob->store(blob->value.ptr(),blob->value.length(),from->charset());
   }
   if (from->real_type() == MYSQL_TYPE_ENUM &&
