On Tue, 30 Jun 2020 09:26:17 +0200
Marc Lehmann <schm...@schmorp.de> wrote:
> Hi, and thanks for your report!
>
> On Mon, Jun 29, 2020 at 07:40:41PM -0500, Rob Hoelz <r...@hoelz.ro>
> wrote:
> > I just upgraded my system (Arch Linux) to Perl 5.32, and I noticed
> > that urxvt started dropping core files upon exit. I dug into this,
> > and it seems that unlike Perl 5.30 or previous versions, Perl 5.32
> > unconditionally calls getenv("PERL_DESTRUCT_LEVEL") in
> > perl_destruct, which is called at atexit handler time. Because
> > rxvt_term makes a copy of the original process environment which it
> > assigns to environ, and then it frees that copy in its destructor
> > when ev_run is wrapping up, this results in a use-after-free when
> > perl_destruct is called, and occasionally a segfault.
> >
> > I patched my local rxvt-unicode package with a workaround - it just
> > sets environ = rxvt_environ after ev_run returns, but maybe a
> > better approach exists.
>
> Hmm, I think the altogether better solution is to simply get rid of
> ~rxvt_perl_interp. Does something like this also work for you?
>
> rxvt_perl_interp::~rxvt_perl_interp ()
> {
> }
>
> i.e. simply remove all code from ~rxvt_perl_interp.
>
> That's basically what I aim for in the next release.
>
That would work, but wouldn't that potentially break users' extensions by
getting rid
of global destruction time? For example, if a user did something like this:
use Guard;
our $g = guard {
# clean up
};
...the clean up code in the guard would never run, right? Also, if any *other*
library
decided to call getenv in an exit handler, the segfault would pop up again.
I'm not super clear
on the details of the copying and swapping of the environment that rxvt-unicode
does (I'm
guessing it has to do with urxvtd), but is there a way the code could be
modified to restore
environ to a valid pointer before main() returns?
-Rob
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