static int r_read_and (RSFD rfd, void *buf);
static int r_read_or (RSFD rfd, void *buf);
static int r_write (RSFD rfd, const void *buf);
static int r_read_and (RSFD rfd, void *buf);
static int r_read_or (RSFD rfd, void *buf);
static int r_write (RSFD rfd, const void *buf);