_xiodump() in xio-ascii.c has questionable length check and needs to compare against (codlen - 1) / 3, not 2 * codlen + 1.  It also should cap the input length at that value.  (3 characters per byte in case of interleaving spaces.)  codlen must be at least 1 (assert?).  xiodump() can write beyond the end of the buffer, but its callers compensate for that by not including the NUL byte in the passed size.