PIPE_BUF
*retval = PIPE_BUF;
if (rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF)
if (space < uio->uio_resid && orig_resid <= PIPE_BUF)
return (kn->kn_data >= PIPE_BUF);
*retval = PIPE_BUF;
wso->so_snd.sb_lowat = PIPE_BUF;
pathconf_row(PIPE_BUF)
posix_constant_row(PIPE_BUF)