Re: segmentation violation in debug mode when watching for an index of an array and rerunning

[arnold]

Hi.

Thanks for the note. The debugger after restarting gets an EOF
when it tries to read a command. I don't know why. I'm not sure
I can trace it down either.

Sorry.

Thanks,

Arnold

Pascal Maugis <pascal.maugis@lsce.ipsl.fr> wrote:

> Hi Arnold,
>
> sorry for not having tested that behavior with the top--newest release 
> as I should have, but that's cool from you to have explained the 
> progress.Having no core dump anymore is less worrying and a kind of 
> relief :)
>
> I understand the difficulty of co-developping, while we rely on a few 
> guys that might leave anytime. If I were consistent as a user, I would 
> enter the debbuger code and make the modification myself. So I'm not 
> going to throw stones at anybody.
>
> Anyway, you've done a great job. I can make do with that small bug. 
> rerunning is not so annoying, and watch points remain pretty useful and 
> manageable that way.
>
> Cheers,
>
> Pascal.
>
> Le 17/09/2022 ?? 21:19, arnold@skeeve.com a ??crit??:
> > Hello.
> >
> > Thanks for the report.
> >
> > Please try the latest release, 5.2.0, made about 2 weeks ago. Here
> > is what I get:
> >
> >     $ cat a.awk
> >     a[1] = 2
> >
> >     $ ./gawk --debug -f a.awk
> >     gawk> b 1
> >     Breakpoint 1 set at file `a.awk', line 1
> >     gawk> run
> >     Starting program:
> >     
> >     Stopping in Rule ...
> >     Breakpoint 1, main() at `a.awk':1
> >     1       a[1] = 2
> >     gawk> watch a[1]
> >     Watchpoint 2: a["1"]
> >     gawk> run
> >     Program already running. Restart from beginning (y/n)? y
> >     Restarting ...
> >     Starting program:
> >     Program exited normally with exit value: 0
> >
> > Now, exiting right away isn't lovely, but at least it's not a core dump.
> > (I will explore it further.)
> >
> > In general, watchpoints are pretty fragile.  The debugger was written
> > by another developer who abandoned the project a long time ago, and is
> > perhaps the part of gawk I am least familiar with, unfortunately.
> >
> > Arnold
> >
> > Pascal Maugis<pascal.maugis@lsce.ipsl.fr>  wrote:
> >
> >> In debug mode, watching for operation on the index of an array is
> >> possible (et very usefull). However, when rerunning the program while
> >> the watch is still active leads to segmentation violation :
> >>
> >>      zsh> echo "a[1]=2" >! a.awk
> >>      zsh> gawk -D -f ./a.awk
> >>      *gawk> b *1
> >>       ?????? Point d'arret 1 defini dans le fichier ????./a.awk???? ligne 1
> >>      *gawk> r*
> >>       ?????? Demarrage du programme??:
> >>       ?????? Arr??t dans Rule...
> >>       ?????? Breakpoint 1, main() ?? ????./a.awk????:1
> >>       ?????? 1???????????? a[1]
> >>      gawk> n
> >>      gawk> w a[1]
> >>      Watchpoint 2: a["1"]
> >>      gawk> r
> >>       ?????? Programme en cours. Reprendre depuis le debut (o/n)??? o
> >>      *?????? gawk: fatal??: erreur interne??: erreur de segmentation*
> >>       ?????? [2]?????? 1001153 abort (core dumped)?? gawk -D -f ./a.awk
> >>
> >> Obviously, after rerun, 'watch' points to an adress which is not
> >> allocated anymore (which is logic). I guess watchpoints on array indexes
> >> should be disabled on rerun, or reenabled only when the array is defined
> >> again as such. Watching a whole array ('watch a') works fine.
> >>
> >> Cheers,
> >>
> >> Pascal.
> >>
> >> Le 13/09/2022 ?? 12:42, Pascal Maugis a ??crit??:
> >>> Hi, as promised here is the strange, unexpected behavior of ++ that
> >>> looks like an error to me, because in "a ++b", a is incremented
> >>> instead of b. "a b++" and "a++ b" produce the correct results however :
> >>>
> >>>      touch a.awk
> >>>      gawk -D -f ./a.awk
> >>>      eval "a=1 ; b=2"
> >>>      eval "print a ++b"???? ; output = 12 : (variables will be
> >>>      incremented after the operation, ok with me as documented)
> >>>      eval "print a b"???????? ; output = 22 : a has been incremented
> >>>      instead of b
> >>>      eval "print a++b"?????? ; output = 22 :
> >>>      eval "print a b"???????? ; output = 32 : a has been incremented
> >>>
> >>> The operation seems to be interpreted as "a++b", the space been
> >>> uninterpreted as a separator
> >>>
> >>> Thanks for your insight,
> >>>
> >>> Cheers,
> >>>
> >>> Pascal.
> >>>
> >>> -- 
> >>> ------------------------------------------------------------------------
> >>>
> >>> *Pascal MAUGIS*
> >>> Mod??lisation hydrologique et changement climatique, PhD
> >>>
> >>> LSCE
> >>>
> >>> Laboratoire des Sciences du Climat et de l'Environnement
> >>> <http://www.lsce.ipsl.fr/>
> >>>
> >>> Unit?? Mixte de Recherche CEA-CNRS-UVSQ (UMR 8212), IPSL, Paris-Saclay
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> >>>
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> >>> ------------------------------------------------------------------------
> >> -- 
> >> ------------------------------------------------------------------------
> >>
> >> *Pascal MAUGIS*
> >> Mod??lisation hydrologique et changement climatique, PhD
> >>
> >> LSCE
> >>
> >> Laboratoire des Sciences du Climat et de l'Environnement
> >> <http://www.lsce.ipsl.fr/>
> >>
> >> Unit?? Mixte de Recherche CEA-CNRS-UVSQ (UMR 8212), IPSL, Paris-Saclay
> >> Equipe MOSAIC : MOdelisation des SurfAces et Interfaces Continentales
> >> B??t. 714, pi??ce 2115
> >> C.E. Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, FRANCE
> >>
> >> e-mail :pascal.maugis@lsce.ipsl.fr
> >> Page perso : FR<http://www.lsce.ipsl.fr/Pisp/pascal.maugis/>  - EN
> >> <http://www.lsce.ipsl.fr/en/Phocea/Pisp/index.php?nom=pascal.maugis>
> >> Tel./Fax : +33 1 69 08 75 24 / +33 1 69 08 77 16
> >>
> >> ------------------------------------------------------------------------
> -- 
> ------------------------------------------------------------------------
>
> *Pascal MAUGIS*
> Mod??lisation hydrologique et changement climatique, PhD
>
> LSCE
>
> Laboratoire des Sciences du Climat et de l'Environnement 
> <http://www.lsce.ipsl.fr/>
>
> Unit?? Mixte de Recherche CEA-CNRS-UVSQ (UMR 8212), IPSL, Paris-Saclay
> Equipe MOSAIC : MOdelisation des SurfAces et Interfaces Continentales
> B??t. 714, pi??ce 2115
> C.E. Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, FRANCE
>
> e-mail : pascal.maugis@lsce.ipsl.fr
> Page perso : FR <http://www.lsce.ipsl.fr/Pisp/pascal.maugis/> - EN 
> <http://www.lsce.ipsl.fr/en/Phocea/Pisp/index.php?nom=pascal.maugis>
> Tel./Fax : +33 1 69 08 75 24 / +33 1 69 08 77 16
>
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