do_open
int do_open = 1, do_close = 0, UNINITIALIZED(flags);
do_open = 0;
do_open = 0;
if (do_open) {
error = do_open(curlwp, NULL, pb, open_flags, open_mode, fd);
error = do_open(l, dvp, pb, flags, mode, fd);
int do_open(struct lwp *, struct vnode *, struct pathbuf *, int, int, int *);