# If the write handle is a dup give it away entirely, close my copy
# of it.
xclose $dad_wtr if $dup_wtr;

##</code><code>##

$ perl -MCarp=verbose a.pl
open3: close(4) failed: Bad file descriptor at /usr/share/perl/5.8/IPC/Open3.pm line 70
        IPC::Open3::xclose(4) called at /usr/share/perl/5.8/IPC/Open3.pm line 218
        IPC::Open3::_open3('open3', 'main', '<&4', '>&STDOUT', '>&STDERR', '/bin/cat') called at /usr/share/perl/5.8/IPC/Open3.pm line 229
        IPC::Open3::open3('<&4', '>&STDOUT', '>&STDERR', '/bin/cat') called at a.pl line 21

##</code><code>##

xclose $dad_wtr if $dup_wtr;

##</code><code>##

if ($dup_wtr) {
    if (fh_is_fd($dad_wtr)) {
        xclose $dad_wtr;
    } else {
        xfdclose xfileno($dad_wtr);
    }
}