use Hash::Util::FieldHash qw(id_2obj);

my %fd;

BEGIN{
    Hash::Util::FieldHash::fieldhash %fd;
    my $open = sub {
        @_ > 2 ? open $_[0],$_[1],$_[2] : open $_[0], $_[1];
    };
    my $close = sub { close $_[0] };

    *CORE::GLOBAL::open = sub {
        my $result = $open->(@_);
        if ($result) {
            $fd{$_[0]} = join " ",@_[1,2],caller;
        }
        $result;
    };
    *CORE::GLOBAL::close = sub {
        my $result = $close->(@_);
        if ($result) {
            $fd{$_[0]} .= " (closed)";
        } else {
            $fd{$_[0]} .= " (close failed)";
        }
        $result;
    };
}

open my $devnull, '>/dev/null' or die;

{
    open my $fh, '>', "blorfldyick" or die;
    print $fh "foo!\n" or die;
    print "(1) ", id_2obj($_), " => $fd{$_}\n" for keys %fd;
    close $fh;
    print "after close\n";
    print "(2) ", id_2obj($_), " => $fd{$_}\n" for keys %fd;
}
print "after scope:\n";
print "(3) ", id_2obj($_), " => $fd{$_}\n" for keys %fd;

open my $devzero, '<', '/dev/zero' or die;

# time passes...

print "later:\n";
print "(4) ", id_2obj($_), " => $fd{$_}\n" for keys %fd;
__END__
(1) GLOB(0xb22190) => >/dev/null  main open.pl 29
(1) GLOB(0xb63780) => > blorfldyick main open.pl 32
after close
(2) GLOB(0xb22190) => >/dev/null  main open.pl 29
(2) GLOB(0xb63780) => > blorfldyick main open.pl 32 (closed)
after scope:
(3) GLOB(0xb22190) => >/dev/null  main open.pl 29
later:
(4) GLOB(0xb363b8) => < /dev/zero main open.pl 42
(4) GLOB(0xb22190) => >/dev/null  main open.pl 29