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Re: An Obscure Bug
- To: Behdad Esfahbod <behdad(at-nospam)bamdad.org>
- Subject: Re: An Obscure Bug
- From: Shlomi Fish <shlomif(at-nospam)techst02.technion.ac.il>
- Date: Tue, 4 Dec 2001 18:35:47 +0200 (IST)
- Cc: <linux-il(at-nospam)linux.org.il>
- Delivered-To: linux.org.il-linux-il@linux.org.il
- In-Reply-To: <Pine.LNX.4.33.0112041949560.16031-100000@gilas.bamdad.org>
- Sender: linux-il-bounce(at-nospam)cs.huji.ac.il
On Tue, 4 Dec 2001, Behdad Esfahbod wrote:
> Didn't segfault on RH7.1, gcc-2.96-85, glibc-2.2.4-19, would you
> please explain the change in your program that solves the segfault?
>
>
Here's the patch:
--- scans.c.old Tue Dec 4 18:30:49 2001
+++ scans.c Tue Dec 4 18:31:24 2001
@@ -89,6 +89,12 @@
/* Mark this state as visited, so it won't be recursed into again. */
ptr_state_with_locations->visited |= FCS_VISITED_VISITED;
+
+ {
+ static int counter=0;
+ printf("Hello!%i!\n", counter++);
+ fflush(stdout);
+ }
/* Count the free-cells */
num_freecells = 0;
As you can see, I just defined a counter and I print and increment it. I
also tried it with a single printf("Hello!\n") and it also solved it.
Regards,
Shlomi Fish
> On Tue, 4 Dec 2001, Shlomi Fish wrote:
>
> >
> > I discovered an obscure bug which I am able to reproduce only under very
> > rare circumctances. Here are the instructions for re-producing it:
> >
> > Download
> > http://vipe.technion.ac.il/~shlomif/obscure-bug.tar.gz
> >
> > Unpack and type make. Then type "source test.sh" at the command line and
> > press enter. Voila - a segfault.
> >
> > Now, "./test.sh" doesn't cause it. The program in question was written by
> > me (it's version 1.11.24 of Freecell Solver), and is compiled with the
> > "-O3" flag by gcc. If it's compiled with "-O2" it doesn't segfault.
> > Nor does it when compiled with kgcc. Moreover, after I made a very small
> > change in the program, it did not segfault either. Finally, running it
> > under gdb cause it not to crash either.
> >
> > I'm using Mandrake 8.1 with KDE 2.2.1 and all of the up-to-current
> > updates. My kernel is 2.4.13-12mdk from cooker.
> >
> > I'll appreciate if anyone can shed some light on the subject.
> >
> > Regards,
> >
> > Shlomi Fish
> >
> > ----------------------------------------------------------------------
> > Shlomi Fish shlomif@t2.technion.ac.il
> > Home Page: http://t2.technion.ac.il/~shlomif/
> > Home E-mail: shlomif@techie.com
> >
> > If:
> > 1. A is A
> > 2. A is not not-A
> > does it imply that
> > 1. B is B
> > 2. B is not not-B
> >
> >
> > =================================================================
> > To unsubscribe, send mail to linux-il-request@linux.org.il with
> > the word "unsubscribe" in the message body, e.g., run the command
> > echo unsubscribe | mail linux-il-request@linux.org.il
> >
>
> --
> Behdad
> 13 Azar 1380, 2001 Dec 4
>
> [Finger for Geek Code]
>
----------------------------------------------------------------------
Shlomi Fish shlomif@t2.technion.ac.il
Home Page: http://t2.technion.ac.il/~shlomif/
Home E-mail: shlomif@techie.com
If:
1. A is A
2. A is not not-A
does it imply that
1. B is B
2. B is not not-B
=================================================================
To unsubscribe, send mail to linux-il-request@linux.org.il with
the word "unsubscribe" in the message body, e.g., run the command
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