Re: [PATCH] fix crashing on amd64

[Rafael Garcia-Suarez <rgarciasuarez mandriva com>]

Ross McFarland wrote:
> On 1/11/06, Thierry Vignaud <tvignaud mandriva com> wrote:
> > we'd experienced application crash on x86_64 for quite some time. it's
> > quite reproductable with 1.11x branch. perl loops while trying to segfaulting.
> >
> > Patch from Rafael Garcia-Suarez <rgarciasuarez mandriva com> traced it
> > and fixed it:
> >
> > On x86_64, the conversions from ptr to int and from int to ptr will
> > loose the highest bits of the pointer, leading to memory access
> > violations. Use the safer macros that perl provides instead.
>
> if those macros are not working it would likely be a bug in glib
> rather than gtk2-perl. what version of glib are you all seeing
> problems with?

There is possibly a bug in glib (2.8.5 and previous versions)
and indeed the macros defined in /usr/lib/glib-2.0/include/glibconfig.h
on an x86_64 architecture won't indeed work.

However, our in-house Gtk/Gnome hacker tells me that those macros
are not really intended to be used like that, because their
purpose is to store ints into void*. A problem that perl does
not have, because it's guaranteed by construct that an IV can hold
a pointer.

The macros I proposed to use instead come directly from perl.h
and are designed for that, and moreover are tested on a sufficiently
large number of architectures to be confident in their safety.
They are documented (in perlguts, section "Pointer-To-Integer
and Integer-To-Pointer") and supported, so I think it's the
right thing to do here. (Note that they're already used elsewhere
in GObject.xs).