char * po_get(struct mount_options *, char *);
po_found_t po_get_numeric(struct mount_options *,
char *, long *);
-unsigned int po_rightmost(struct mount_options *,
+int po_rightmost(struct mount_options *,
const char *keys[]);
po_found_t po_remove_all(struct mount_options *, char *);
void po_destroy(struct mount_options *);