Re: interface groups

[Henning Brauer <lists-openbsdtech_(_at_)_bsws_(_dot_)_de>]

* Artur Grabowski <art_(_at_)_blahonga_(_dot_)_org> [2004-06-22 21:34]:
> Henning Brauer <lists-openbsdtech_(_at_)_bsws_(_dot_)_de> writes:
> 
> > * Philipp Buehler <pb_(_at_)_openbsd_(_dot_)_org> [2004-06-22 10:06]:
> > > +	TAILQ_FOREACH(ifgp, &ifp->if_groups, group_list) {
> > > +			TAILQ_REMOVE(&ifp->if_groups, ifgp, group_list);
> > 
> > no... see manpage
> > 
> > NOTES
> >      Trying to free a list in the following way is a common error:
> > 
> >            LIST_FOREACH(var, head, entry)
> >                    free(var);
> >            free(head);
> > 
> >      Since var is free'd, the FOREACH() macro refers to a pointer that may
> >      have been reallocated already.  Proper code needs a second variable.
> > 
> >            for (var = LIST_FIRST(head); var != LIST_END(head); var = nxt) {
> >                    nxt = LIST_NEXT(var, entry);
> >                    free(var);
> >            }
> >            LIST_INIT(head);        /* to put the list back in order */
> 
> Stop giving bad advice. :)
> 
> while ((foo = TAILQ_FIRST(..)) != NULL) {
>         TAILQ_REMOVE(foo ...);
>         free(foo);
> }

the manpage example is bad for draining the entire queue.
the point however is that TAILQ_REMOVE in a TAILQ_FOREACH loop is 
going to bomb out.

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