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[Frama-c-discuss] Validating pointers

  • Subject: [Frama-c-discuss] Validating pointers
  • From: Patrick.Baudin at (BAUDIN Patrick)
  • Date: Wed, 01 Jul 2009 16:09:22 +0200
  • In-reply-to: <002701c9fa3c$6fc716b0$4f554410$@com>
  • References: <002701c9fa3c$6fc716b0$4f554410$@com>

Hi B?rbara,
> To validate the pre-conditions on "g", I have to assume that: 
> *\valid*(e) && *\valid*(e->a) && *\valid*(&(e->a));
> My question is, why I have to assume *\valid*(&(e->a)) ?
This seems to be a lack of Jessie.
> Assuming just that *\valid*(e) && *\valid*(e->a) is not sufficient?
Yes it should be from an ACSL point of view.
> If I assume that e!=NULL && e->a!=NULL, this does not implies that 
> &(e->a) != NULL?
Just a warning, *\valid*(e) is stronger than e!=NULL since *\valid*(e) 
speaks also about the liveness and the size of the pointed location.

But anyway *\valid*(e) => *\valid*(&(e->a)) is  a valid ACSL theorem 
when the formula is correctly type-checked and the type of (*e) isn't a 
incomplete struct/union type.


Patrick Baudin,
CEA, LIST, SOL, 91191 Gif-surYvette cedex, France.
tel: +33 (0)1 6908 2072

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