Re: Old dblib.c bug still there

Well, I use defncopy all the time. :)  Glad we worked through this.  Should
I mail this to Freddy directly or is attaching it here (as I've done) good
enough?

On Wed, Jun 15, 2016 at 3:37 AM, Thompson, William <[email protected]
> wrote:

> Hi.
>
> Glad you found a solution!
> From looking at the code, I can see why that would be just what was needed!
> The STRINGBIND is basically saying "don't strip any trailing blanks off
> the returned string"
> Passing 0 as the size of the destination field is basically telling dbbind
> "don't worry, I've got enough space to take whatever you're giving me,
> just give me what you've got"
> So it should the give you the stored procedure text as is.
>
> The only worry in programming terms is that 16000 bytes won't be enough to
> hold what sql server gives us,
> But think that highly unlikely, given we know what we're selecting...
>
> My guess would be that the users of defncopy could be counted on a couple
> of hands.
> The stripping off blanks behaviour would mess up many stored procedures
> where a syntactically significant blank
> fell at the end of one of the syscomments rows, e.g.
> row 1: "....SELECT * FROM "
> row 2: "MYTABLE WHERE....."
>
> so your fix is an improvement I have no doubt!
> Make the change, and give it to Freddy as a patch.
>
> If this would then be your first contribution to the project, welcome!
>
> Bill
>
>
> -----Original Message-----
> From: FreeTDS [mailto:[email protected]] On Behalf Of Nem
> W Schlecht
> Sent: 14 June 2016 16:59
> To: FreeTDS Development Group
> Subject: Re: [freetds] Old dblib.c bug still there
>
> On Tue, Jun 14, 2016 at 7:43 AM, Thompson, William <
> [email protected]
> > wrote:
>
> > I Agree with Freddy - if you want to make a change to test it out, I'd
> > make the change to defncopy.c Try changing that NTBSTRINGBIND to plain
> > old STRINGBIND, and see how that affects the behaviour.
> > It looks to me like it should stop the trailing blanks from being
> > stripped off
> >
> >
> >
> Gave this a shot.  In my test stored procedure, it now adds around 12,000
> extra spaces. Not quite what I was hoping for.  :)  Looks like it wants to
> pad it out to 16,000 chars.
>
> I think it would work correctly if limited_dest_space weren't set in
> dblib.c copy_data_to_host_var().
>
> Yes, I changed line 577 of defncopy.c from:
>
> erc = dbbind(dbproc, ctext, NTBSTRINGBIND, sizeof(sql_text), (BYTE *)
> sql_text);
>
> to:
>
> erc = dbbind(dbproc, ctext, STRINGBIND, 0, (BYTE *) sql_text);
>
>
> And now defncopy is working correctly on my test stored procedure.  Is
> this going to mess anything else up, though?
>
>
>
>
> >
> > -----Original Message-----
> > From: FreeTDS [mailto:[email protected]] On Behalf Of
> > Frediano Ziglio
> > Sent: 14 June 2016 12:58
> > To: FreeTDS Development Group
> > Subject: Re: [freetds] Old dblib.c bug still there
> >
> > 2016-06-12 18:59 GMT+01:00 Nem W Schlecht <[email protected]>:
> > > Hello all,
> > >
> > > First off, I just want to thank all of the developers in this
> > > community for continuing work on such a useful and excellent
> > > application.  I cannot thank and appreciate you all enough!  Thank
> > > you,
> > Thank You, THANK YOU!!
> > >
> > >
> > > I recently grabbed the last stable release and came across an issue
> > > that seems to constantly be plaguing me and has been around for a
> > > long time.  I had reported this back in July of 2014, but the
> > > proposed solution (stripping all but one space) would still screw up
> > > some of my stored procedures (that have lots of spaces in strings
> > > for formatting
> > purposes).
> > >
> > > My original post and reply:
> > >   http://lists.ibiblio.org/pipermail/freetds/2014q3/028964.html
> > >   http://lists.ibiblio.org/pipermail/freetds/2014q3/028966.html
> > >
> > > The issue is with lines 7311-7314 in dblib.c:
> > >
> > >    7311                 case NTBSTRINGBIND: /* strip trailing blanks,
> > null
> > > term */
> > >    7312                     while (srclen && src[srclen - 1] == ' ') {
> > >    7313                         --srclen;
> > >    7314                     }
> > >
> > > Looks like something good to do, right?  Get rid of any blanks that
> > > we don't need.  However, this keeps messing up my output when I use
> > "defncopy"
> > > to dump out some of my stored procedures.
> > >
> >
> > Well... this is the expected behaviour of NTBSTRINGBIND. The problem
> > is not in dblib.c but in defncopy that expects a different behaviour.
> >
> > > If it just so happens that you have a large stored procedure or
> > > large string in that stored procedure *and* there are one or more
> > > spaces exactly at a multiple of byte 4000, dblib.c will strip out
> > > the spaces, causing either data corruption or an SQL syntax error in
> > > the stored
> > procedure.
> > >
> > > I'm attaching an example to reproduce the issue.
> > >
> > > Load in 'dbo.big_proc-load.sql' and then immediately run 'defncopy'
> > > to dump it back out.  Each digit should have 40 spaces between it,
> > > but on line 96, it only contains 8 spaces.  dblib grabbed the first
> > > 4000 bytes, saw there there were spaces, and truncated it back to
> > > the last
> > non-space character.
> > >
> > > I've actually had this happen (just by pure chance) in actual code
> > > as well, where a line like this:
> > >
> > >      SELECT some_field_name AS some_field_alias
> > >
> > > has been turned into:
> > >
> > >      SELECT some_field_nameAS some_field_alias
> > >
> > > Thus causing an error the next time the stored procedure is run,
> > > since the field name is now incorrect.
> > >
> > > I've modified my copy of dblib.c and commented out lines 7312-7314
> > > (as I did so 2 years ago and I've had to negative effects), but
> > > would like to hear thoughts/opinions of the developers and would
> > > really like this issue fixed.
> > >
> > > Again, thank you all so much for all of your hard work on FreeTDS!
> > >
> >
> > Seems that all bindings with varlen != 0 (as you don't want an
> > overflow
> > too):
> > - does blank padding;
> > - are limited;
> > - strip blanks.
> > All stuff you don't want for your usage. The possible solution is to
> > not use binding but dbdata and family.
> >
> > Frediano
> > _______________________________________________
> > FreeTDS mailing list
> > [email protected]
> > http://lists.ibiblio.org/mailman/listinfo/freetds
> >
> > ----------------------------------------------------------------------
> > This message, and any attachments, is for the intended recipient(s)
> > only, may contain information that is privileged, confidential and/or
> > proprietary and subject to important terms and conditions available at
> > http://www.bankofamerica.com/emaildisclaimer.   If you are not the
> > intended recipient, please delete this message.
> > _______________________________________________
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> >
>
>
>
> --
> Nem W Schlecht <http://www.emptec.com/>
>  "Perl did the magic.  I just waved the wand."
> _______________________________________________
> FreeTDS mailing list
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>
> ----------------------------------------------------------------------
> This message, and any attachments, is for the intended recipient(s) only,
> may contain information that is privileged, confidential and/or proprietary
> and subject to important terms and conditions available at
> http://www.bankofamerica.com/emaildisclaimer.   If you are not the
> intended recipient, please delete this message.
> _______________________________________________
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>



-- 
Nem W Schlecht                   [email protected]
Empyreal Technologies    http://www.emptec.com/
 "Perl did the magic.  I just waved the wand."

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diff --git a/freetds-1.00.3/src/apps/defncopy.c b/freetds-1.00.3-defncopyfix/src/apps/defncopy.c
index e76d1b3..4890492 100644
--- a/freetds-1.00.3/src/apps/defncopy.c
+++ b/freetds-1.00.3-defncopyfix/src/apps/defncopy.c
@@ -574,7 +574,7 @@ print_results(DBPROCESS *dbproc)
 			assert(sizeof(sql_text) >= dbcollen(dbproc, ctext));
 			return 0;
 		}
-		erc = dbbind(dbproc, ctext, NTBSTRINGBIND, sizeof(sql_text), (BYTE *) sql_text);
+		erc = dbbind(dbproc, ctext, STRINGBIND, 0, (BYTE *) sql_text);
 		if (erc == FAIL) {
 			fprintf(stderr, "%s:%d: dbbind(), column %d failed\n", options.appname, __LINE__, ctext);
 			return -1;