* @note sets errno = EDOM if src contains invalid characters
* @note sets errno = EINVAL if src is an invalid base64 tail
*/
-ssize_t base64_decode_tail_using_maps(const base64_maps_t *maps, char *dest,
+ssize_t base64_decode_tail_using_maps(const base64_maps_t *maps, char dest[3],
const char *src, size_t srclen);