Frama-C-discuss mailing list archives

This page gathers the archives of the old Frama-C-discuss archives, that was hosted by Inria's gforge before its demise at the end of 2020. To search for mails newer than September 2020, please visit the page of the new mailing list on Renater.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Frama-c-discuss] strlen axioms and memory space

Hi Denis,

Your link actually leads to even more "interesting" thoughts. My axiom
stated that any strlen should be less or equal than UINTPTR_MAX. But
assuming that strings s1 and s2 are not overlapping, the sum of their
lengths is seemingly less or equal than UINTPTR_MAX.


On Thu, Jul 30, 2020 at 2:44 PM Denis Efremov <efremov at ispras.ru> wrote:

> Hi,
>
> On 7/30/20 11:36 PM, Yurii Rashkovskii wrote:
> >
> > I have a question / thought to bounce off. I've been recently trying to
> prove a few properties on some trivial functions in a small project of mine
> (https://github.com/yrashk/clam).
> >
> > I ran into an interesting aspect where I needed to do extensive checks
> on certain counters not hitting UINTPTR_MAX. I have managed to simplify
> that with a rather trivial axiom:
> >
> >
> https://github.com/yrashk/clam/commit/e84af3bf8d72ebdcec392589e189952d560ba28a
> >
> > (obviously, I would have preferred an actual prove, but I am but a
> novice)
> >
> > I am wondering if any thought has been previously given on such cases
> where, for example `strlen` axioms are bound by \forall ℤ which is
> admittedly wider than pointers would allow?
> >
> > Is my approach anywhere close to reasonable? Should Frama-C axiomatics
> include more consideration for the [limited] pointer integer universe?
>
> I faced it while proving strcat
>
> https://github.com/evdenis/verker/blob/master/src/strcat.h#L14
>
> Regards,
>
> Denis
>
>

-- 
Y.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.gforge.inria.fr/pipermail/frama-c-discuss/attachments/20200730/bb2996f8/attachment-0001.html>