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

  • Subject: [Frama-c-discuss] strlen axioms and memory space
  • From: efremov at ispras.ru (Denis Efremov)
  • Date: Fri, 31 Jul 2020 00:44:42 +0300
  • In-reply-to: <CA+RLCQx4DaVUCrK__=ocAXYMzKrzCtQcxoc9eMfgV6i3JuXVXw@mail.gmail.com>
  • References: <CA+RLCQx4DaVUCrK__=ocAXYMzKrzCtQcxoc9eMfgV6i3JuXVXw@mail.gmail.com>
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