PIPE_WANTR
rpipe->pipe_state |= PIPE_WANTR;
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
cpipe->pipe_state &= ~(PIPE_WANTD | PIPE_WANTR | PIPE_WANTW);
(kf->pipe_state & PIPE_WANTR) ? "R" : "",