FreeTDS Development Group

[Frediano Ziglio <freddyz77 AT tin.it>]

> > 
> > On Feb 18, 2004, at 2:51 PM, Jonathan Monroe wrote:
> > 
> > > I think I have found an issue with the way the SQL_C_BINARY 
> > data type 
> > > is handled in the ODBC code.
> > [snip]
> > 
> > It just occurred to me that the patch I provided for 
> > convert_tds2sql.c 
> > only fixed the problem for varchar columns - other column types will 
> > still have some sort of conversion performed.  The better way of 
> > handling it is probably to treat SQL_C_BINARY as a special 
> > case and not 
> > call tds_convert() at all.
> > 
> > So, the new patch would look like this:
> > 
> > convert_tds2sql.c:  v1.37:
> > 81,84c81,102
> > <       nRetVal = tds_convert(context, srctype, src, srclen, 
> > nDestSybType, &ores);
> > <       if (nRetVal < 0)
> > <               return nRetVal;
> > <
> > ---
> >  >       if (desttype == SQL_C_BINARY)
> >  >       {
> >  >               /* just copy the raw bytes */
> >  >               if (destlen > 0) {
> >  >                       cplen = (destlen > srclen) ? srclen 
> > : destlen;
> >  >                       assert(cplen >= 0);
> >  >                       /* do not NULL terminate binary buffer */
> >  >                       memcpy(dest, src, cplen);
> >  >                       ret = cplen;
> >  >               } else {
> >  >                       /* if destlen == 0 we return only length */
> >  >                       if (destlen != 0)
> >  >                               ret = TDS_FAIL;
> >  >               }
> >  >       }
> >  >       else
> >  >       {
> >  >               nRetVal = tds_convert(context, srctype, src, srclen, 
> > nDestSybType, &ores);
> >  >               if (nRetVal < 0)
> >  >                       return nRetVal;
> >  >       }
> >  >
> > 236,250c254
> > <               tdsdump_log(TDS_DBG_FUNC, "convert_tds2sql: 
> > outputting 
> > binary data destlen = %d \n", destlen);
> > <
> > <               ret = nRetVal;
> > <               if (destlen > 0) {
> > <                       cplen = (destlen > nRetVal) ? nRetVal 
> > : destlen;
> > <                       assert(cplen >= 0);
> > <                       /* do not NULL terminate binary buffer */
> > <                       memcpy(dest, ores.ib, cplen);
> > <               } else {
> > <                       /* if destlen == 0 we return only length */
> > <                       if (destlen != 0)
> > <                               ret = TDS_FAIL;
> > <               }
> > <
> > <               free(ores.ib);
> > ---
> >  >               /* handled as special case above */
> > 
> > 
> > Anybody see any problems with doing it this way?
> > 
> > Jonathan Monroe
> > 
> 
> You spot a real problem. I don't know if is correct to handle varchar as
> a binary string (ie: '012345') however I don't know the real behaviour
> for other types. For instance how MS ODBC return a datetime?? Same
> format of wire (as FreeTDS does now) or converting to TIMESTAMP before
> ?? Some tests are needed to handle this type...
> 

SQL_C_BINARY behavior is correct and reflect MS ODBC one. I don't know
why but all library (dblib, CTLib and ODBC) have the same behavior.
I'm doing some tests for DATETIME and others type.

freddy77