Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!purdue!bu-cs!bloom-beacon!TUB.BITNET!net
From: net@TUB.BITNET (Oliver Laumann)
Newsgroups: comp.windows.x
Subject: Re: Xt Problem [XtDispatchEvent()]
Message-ID: <8902161223.AA01554@tub.UUCP>
Date: 16 Feb 89 12:23:07 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 27

> > XtDispatchEvent() is not re-entrant.
>
> According to Paul Asente, XtDispatchEvent is fully reentrant in X11R3.

But it isn't.

XtDispatchEvent() sets a global variable to point to a local
variable in the line reading

    _XtDestroyList = &destroyList;

(destroyList is a local variable of XtDispatchEvent()).  The value
of _XtDestroyList is restored at the end of XtDispatchEvent().

When XtDispatchEvent() is left via a non-local goto (e.g. by calling
longjmp() from within a callback), the value of _XtDestroyList
becomes meaningless.  This can cause a subsequent call to XtDestroyWidget()
to produce a segmentation fault or bus error.

Am I missing something?

Oh, by the way, the line preceding the one quoted above in Event.c
is a comment reading "This is pretty gross.".

Regards,
--
Oliver Laumann              net@TUB.BITNET              net@tub.UUCP