Bug #40076 "Functions Return String" option does not set the proper encoding for the string

• Submitted: 16 Oct 2008 12:19
• Modified: 10 Nov 2008 14:28
• Reporter: Bogdan Degtyariov
• Status: Closed
• Category: Connector / NET
• Severity: S3 (Non-critical)
• Version: 5.2.3
• OS: Windows
• Assigned to: Bogdan Degtyariov
• CPU Architecture: Any

[16 Oct 2008 12:19] Bogdan Degtyariov

Description:
Even though the option ("Functions Return String=true;") is set, the result of SELECT DES_DECRYPT() contains "??" instead of national symbols ("Trädgårdsvägen" is displayed as "Tr?dg?rdsv?gen"). 

This option makes Connector/NET to ignore VARBINARY type and set VARCHAR to the result metadata. However, setting the correct type is not enough because the result received from the server is processed using ASCII encoding instead of default connection encoding.

How to repeat:
        private void button1_Click(object sender, EventArgs e)
        {
            string result = "";
            MySqlConnection con = null;
            try {
                con = new MySqlConnection("server=localhost;database=test;user id=****;pwd=****;Pooling=false;Functions Return String=true;"); //
                con.Open();

                MySqlCommand cmd = new MySqlCommand();
                cmd.Connection = con;

                cmd.CommandText = "DROP TABLE IF EXISTS cnet_binary_test;";
                cmd.ExecuteNonQuery();

                cmd.CommandText = "CREATE TABLE cnet_binary_test (id int auto_increment primary key," + 
                                  "vc1 varchar(64), vc2 varchar(64))DEFAULT CHARSET=Latin1;";
                cmd.ExecuteNonQuery();

                cmd.CommandText = "INSERT INTO cnet_binary_test (vc1) VALUES ('Trädgårdsvägen')";
                cmd.ExecuteNonQuery();

                cmd.CommandText = "UPDATE cnet_binary_test SET vc2=des_encrypt(vc1)";
                cmd.ExecuteNonQuery();

                cmd.CommandText = "SELECT vc1, des_decrypt(vc2) FROM cnet_binary_test";
                MySqlDataReader reader = cmd.ExecuteReader();
                if( reader.Read() ) {
                    result = reader.GetString(0);
                    result += "\r\n" + reader.GetString(1);
                }
            reader.Close();
            } catch( Exception ex ) {
                string error = ex.Message.ToString();
                MessageBox.Show(error);
            } finally {
                if( con != null )
                con.Close();
            }
            MessageBox.Show(result);
        }
    }
}

Suggested fix:
--- NativeDriver.cs.old	2008-10-16 14:13:37.000000000 +0200
+++ NativeDriver.cs	2008-10-16 14:13:40.000000000 +0200
@@ -724,11 +724,17 @@
                 stream.ReadInteger(2); // reserved
             }
 
-            if (charSets != null && field.CharacterSetIndex != -1)
+            if (charSets != null && field.CharacterSetIndex != -1 &&
+                !(connection.Settings.FunctionsReturnString && field.CharacterSetIndex == 63))
             {
-                CharacterSet cs = CharSetMap.GetChararcterSet(Version, (string) charSets[field.CharacterSetIndex]);
+                CharacterSet cs = CharSetMap.GetChararcterSet(Version, (string)charSets[field.CharacterSetIndex]);
                 field.MaxLength = cs.byteCount;
-                field.Encoding = CharSetMap.GetEncoding(version, (string) charSets[field.CharacterSetIndex]);
+                field.Encoding = CharSetMap.GetEncoding(version, (string)charSets[field.CharacterSetIndex]);
+            }
+            else if (connection.Settings.FunctionsReturnString && field.CharacterSetIndex == 63)
+            {
+                /* If binary, use default connection encoding */
+                field.Encoding = Encoding;
             }
 
             return field;

[20 Oct 2008 19:28] Bugs System

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/56617

[20 Oct 2008 19:29] Reggie Burnett

- fixed bug where specifying 'functions return string=yes' would cause strings to be returned using the 'binary' charset which would not properly render some characters.  Now the connection character set is used. (bug #40076)  

Fixed in 5.2.4

[10 Nov 2008 14:28] Tony Bedford

Added an entry to the 5.2.4 changelog:

The connection string option Functions Return String did not set the correct encoding for the result string. Even though the connection string option Functions Return String=true; is set, the result of SELECT DES_DECRYPT() contained “??” instead of the correct national character symbols.