PF_WOPEN
pty->pt_flags |= PF_WOPEN;
pty->pt_flags &= ~PF_WOPEN;
pty->pt_flags &= ~(PF_WOPEN|PF_STOPPED|PF_NOSTOP);
if (pty->pt_flags & PF_WOPEN) {
pty->pt_flags &= ~PF_WOPEN;
pty->pt_flags &= (PF_WOPEN|PF_STOPPED|PF_NOSTOP);