FreeTDS Development Group

[Frediano Ziglio <freddy77 AT gmail.com>]

2009/10/14 miscmail <miscmail AT fingerpost.co.uk>:
> Hi all
>
> I am trying to upgrade from freetds 0.62 to 0.82 and have a small
> problem with dbwritetext
>
> In my program, if the data length < system_max then the program does a :
>
>  - dbwritetext with a data buffer set to NULL and the length set to
> the actual size.
>  - then a loop with dbmoretext to upload the chunks
>
> But in 0.82 it just hangs ... with an error .....
>
> In dblib/unittest/t0013.c there is some code which is similar to mine
> BUT it is wasted with a ''ifndef"
>
> When I tried a file around 400k - it worked fine even though the 'set
> textsize' is  64512
>
> So then I set the flag (and added missing variables numtowrite and
> numwritten) :
>        #define DBWRITE_OK_FOR_OVER_4K
>
> .. recompiled and got the same hang as my code does
>
> The actual code in t0013 is :
>
>         if (dbwritetext(dbproc, objname, textPtr, DBTXPLEN,
> timeStamp, FALSE, isiz, NULL) != SUCCEED)
>                 return 15;
>         dbsqlok(dbproc);
>         dbresults(dbproc);
>
>         numtowrite = 0;
>         /* Send the update value in chunks. */
>         for (numwritten = 0; numwritten < isiz; numwritten +=
> numtowrite) {
>                 numtowrite = (isiz - numwritten);
>                 if (numtowrite > BLOB_BLOCK_SIZE)
>                         numtowrite = BLOB_BLOCK_SIZE;
>                 dbmoretext(dbproc, (DBINT) numtowrite, blob +
> numwritten);
>         }
>         dbsqlok(dbproc);
>         while (dbresults(dbproc) != NO_MORE_RESULTS);
>
> I checked the src/dblib/dblib.c an found there is a check-exit-if-null
> on the 'text' buffer parameter
> - around line 6261 in dblib.c 0.82 there is a
>        CHECK_NULP(text, "dbwritetext", 8, FAIL);
>        which looks like it is doing the damage.
>
> which means a call with a NULL text buffer never gets to do anything !
>
> There is a snippet of code a few lines further down which catches
> NULLs (below) so I wonder if that CHECK is superfluous :
>
>         if (!text) {
>                 dbproc->text_size = size;
>                 dbproc->text_sent = 0;
>                 return SUCCEED;
>         }
>
> Is there something new in how dbwritetext works - or should I just
> comment out the offending CHECK_NULP line  (BTW it aint in freetds
> 0.62)?
>
> Waddatink
>
> chris
>

Fixed in CVS (both 0.82 branch and HEAD). You can find post 0.82 patch
at http://freetds.sourceforge.net/.

freddy77