[Mono-dev] Odbc and varchar - patch for varchars longer than 255

[A Nagappan]

Hi,
  Can you provide a sample test-case ?

Thanks
Nagappan


--
Nagappan A <anagappan at novell.com>
Linux Desktop Testing Project - http://ldtp.freedesktop.org
http://nagappanal.blogspot.com

Novell, Inc.
SUSE* Linux Enterprise 10
Your Linux is ready*
http://www.novell.com/linux




>>> On Tue, Jun 19, 2007 at  3:53 PM, in message
<200706191223.32378.mbd at dbc.dk>,
Mads Bondo Dydensborg <mbd at dbc.dk> wrote: 
> Hi there.
> 
> I have had problems with strings containing binary 0, when retrieved
through 
> 
> the mono stack. Looking at OdbcDataReader, there seems to be a
difference 
> between how GetBytes and GetValue( "varchar" ) works. 
> 
> GetBytes has this:
> 
> 10                         if (copyBuffer) {
>     311                                 int i = 0;
>     312                                 while (tbuff [i] !=
libodbc.C_NULL) 
> {
>     313                                         buffer [bufferIndex +
i] = 
> tbuff [i];
>     314                                         i++;
>     315                                 }
>     316                                 returnVal = i;
>     317                         }
>     318                         return returnVal;
>     31
> 
> Whereas GetValue has this (sorry about the formatting):
> 
>  696                                 case OdbcType.VarChar:
>     697                                         bufsize =
(col.MaxLength < 
> 255 ? (col.MaxLength+1) : 255);
>     698                                         buffer = new 
> byte[bufsize];  // According to sqlext.h, use SQL_CHAR for both char
and 
> varchar
>     699                                         StringBuilder sb1 =
new 
> StringBuilder ();
>     700                                         do {
>     701                                                 ret = 
> libodbc.SQLGetData (hstmt, ColIndex, col.SqlCType, buffer, bufsize,
ref 
> outsize);
>     702                                                 if (ret == 
> OdbcReturn.Error)
>     703                                                        
break;
>     704                                                 if (ret != 
> OdbcReturn.NoData && outsize!=- 1) {
>     705                                                         if
(outsize < 
> 
> bufsize)
>     706                                                              
  
> sb1.Append
(System.Text.Encoding.Default.GetString(buffer,0,outsize));
>     707                                                         else
>     708                                                              
  
> sb1.Append
(System.Text.Encoding.Default.GetString(buffer,0,bufsize));
>     709                                                 }
>     710                                         } while (ret != 
> OdbcReturn.NoData);
>     711                                         DataValue =
sb1.ToString ();
>     712                                         break;
> 
> According to 
> http://msdn.microsoft.com/library/default.asp?url=/library/en-
us/odbc/htm/odb
> csqlgetdata.asp
> "It is up to the application to reassemble the parts, taking care to
remove 
> the null- termination character from intermediate parts of character
data. "
> 
> This patch fixes my problem:
> 
> Index: OdbcDataReader.cs
> ===================================================================
> ---  OdbcDataReader.cs   (revision 80063)
> +++ OdbcDataReader.cs   (working copy)
> @@ - 705,7 +705,7 @@
>                                                         if (outsize <

> bufsize)
>                                                                
sb1.Append 
> (System.Text.Encoding.Default.GetString(buffer,0,outsize));
>                                                         else
> -                                                               
sb1.Append 
> (System.Text.Encoding.Default.GetString(buffer,0,bufsize));
> +                                                              
sb1.Append 
> (System.Text.Encoding.Default.GetString(buffer,0,bufsize- 1));
>                                                 }
>                                         } while (ret !=
OdbcReturn.NoData);
>                                         DataValue = sb1.ToString ();
> 
> It assumes any fragment, with more data, always contains a binary
zero on 
> the 
> last position. This may or may not be the case -  some Odbc expert
should 
> probably look at it. There could be a problem with NVarchar also.
> 
> Regards,
> 
> Mads