Re: [bug-gawk] UNFIELD bug in stable branch

[Andrew J. Schorr]

On Mon, Jan 23, 2017 at 08:10:33AM -0700, address@hidden wrote:
> Wow. I'm really, really sorry that this cost you some much time
> and trouble.  Please accept my apologies.

No worries. In retrospect, it's hard to understand how it took me so
long to find and fix the bug. But when one starts with a medium-size script
and nontrivial input files, it's hard to drill down. Sigh.

-Andy

> I do still have the files for Carlo. I'll put them where you can
> get to them later, I'm on a train at the moment... :-)
> 
> Thanks,
> 
> Arnold
> 
> "Andrew J. Schorr" <address@hidden> wrote:
> 
> > Hi,
> >
> > On Mon, Jan 23, 2017 at 07:11:42AM -0700, address@hidden wrote:
> > > Hi. I'll review.
> >
> > Thanks.
> >
> > > I bet this fixes the bug Carlo reported a while back. If you have
> > > a chance, please see if it does. If not I'll get to it.
> >
> > He seems to have deleted the branch that demonstrates the bug:
> >
> > bash-4.2$ git clone https://github.com/CarloWood/Firmware.git
> > Cloning into 'Firmware'...
> > remote: Counting objects: 198439, done.
> > remote: Total 198439 (delta 0), reused 0 (delta 0), pack-reused 198439
> > Receiving objects: 100% (198439/198439), 80.61 MiB | 7.08 MiB/s, done.
> > Resolving deltas: 100% (147746/147746), done.
> > bash-4.2$ cd Firmware
> > bash-4.2$ git checkout cw_fix_headers
> > error: pathspec 'cw_fix_headers' did not match any file(s) known to git.
> >
> > I don't have a copy saved; do you? Should we ask him to make it available
> > again?
> >
> > > Thank you very much for investigating and coming up with a fix.
> >
> > It cost me at least 5 hours yesterday. I had just completed an O/S 
> > conversion
> > from Fedora to CentOS when I noticed that a complicated script was
> > malfunctioning. It turned out that on the old O/S, it was using an old copy 
> > of
> > xgawk 3.1.6.  After upgrading to gawk 4.1.x, it no longer worked. What a
> > nightmare. I hope the fix is correct, since I already put it into 
> > production on
> > my network. I don't see how disabling the FIELD bit can be correct...
> >
> > Regards,
> > Andy
> >
> > > "Andrew J. Schorr" <address@hidden> wrote:
> > > 
> > > > On Sun, Jan 22, 2017 at 07:39:22PM -0500, Andrew J. Schorr wrote:
> > > > > On Sun, Jan 22, 2017 at 06:48:31PM -0500, Andrew J. Schorr wrote:
> > > > > > Here's a much simpler version. The master branch correctly prints 
> > > > > > "apple",
> > > > > > whereas the gawk-4.1-stable branch prints "pear". Ugh.
> > > > > 
> > > > > According to git bisect:
> > > > > 
> > > > > ac7bcb4c8cdc07f974205709616fda91a447c0f1 is the first bad commit
> > > > > commit ac7bcb4c8cdc07f974205709616fda91a447c0f1
> > > > > Author: Arnold D. Robbins <address@hidden>
> > > > > Date:   Mon Nov 17 17:25:05 2014 +0200
> > > > > 
> > > > >     Add unfield code in several spots.
> > > > > 
> > > > > :100644 100644 9910ea72481724aa5b94a7f4c61bb5a36dc74dab 
> > > > > 2901f60e557960a02bb1f3e6a13fb17db44d8a82 M      interpret.h
> > > >
> > > > The attached patch to the UNFIELD macro in interpret.h fixes the bug 
> > > > and passes
> > > > "make check" and "make valgrind-noleak". I basically copied my revised 
> > > > version
> > > > of the UNFIELD macro from the master branch. That being said, I never 
> > > > really
> > > > understood what motivated the previous (buggy) version of UNFIELD in 
> > > > the stable
> > > > branch, so I'm afraid I could be missing a subtle problem. It never 
> > > > made sense
> > > > to me that disabling the FIELD bit could work, but I had the sense that 
> > > > this
> > > > code was never hit. I seem to have found the code sequence that tickles
> > > > that scenario. I think the FIELD bit was getting disabled in 
> > > > Op_store_field or
> > > > Op_store_var.
> > > >
> > > > Arnold -- let me know if you'd like me to commit this along with the new
> > > > test case.
> > > >
> > > > Regards,
> > > > Andy
> > > 
> >
> > -- 
> > Andrew Schorr                      e-mail: address@hidden
> > Telemetry Investments, L.L.C.      phone:  917-305-1748
> > 545 Fifth Ave, Suite 1108          fax:    212-425-5550
> > New York, NY 10017-3630
> 

-- 
Andrew Schorr                      e-mail: address@hidden
Telemetry Investments, L.L.C.      phone:  917-305-1748
545 Fifth Ave, Suite 1108          fax:    212-425-5550
New York, NY 10017-3630