Date: Fri, 11 Dec 1998 11:57:59 -0800 (PST) From: Archie Cobbs <archie@whistle.com> To: freebsd-current@FreeBSD.ORG Subject: Re: inetd: realloc/free bug Message-ID: <199812111957.LAA27876@bubba.whistle.com> In-Reply-To: <199812111940.LAA27652@bubba.whistle.com> from Archie Cobbs at "Dec 11, 98 11:40:58 am"
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Archie Cobbs writes:
> > What horror results from doing this in a signal handler? On e-paper, it
> > seems to give the desired effect, but does a return from a signal
> > handler implicitly call sigreturn(2) when it returns? And if so, is
> > there anything that requires this to happen?
>
> I guess I was thinking in terms of the event library model; that is,
> you don't handle the signal event in the signal handler (because in
> general the event handler could call malloc(), etc), but rather you
> simply set a flag (call it "signalFlag").
>
> The race condition is getting a signal between the first and second
> lines below:
>
> sigprocmask(SIG_UNBLOCK ..) /* unblock signals */
> r = select(...) /* wait for event */
> sigprocmask(SIG_BLOCK ..) /* block signals */
>
> if (signalFlag || r > 0) {
> ... /* handle event(s) */
> }
OK, if you call the signal "event" handler from within the actual
signal handler because of a signal received bewtween lines 1 and 2,
that's OK because you know you're not in a recursive malloc() situation.
So I guess that would work.
-Archie
___________________________________________________________________________
Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com
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