SECSIZ
if ((err = !(fs->buf = malloc(SECSIZ)) ? errno : 0) ||
if (cv2(bs->bpb.secsiz) != SECSIZ)
if ((off = offset & (SECSIZ - 1))) {
offset += SECSIZ;
if ((n = SECSIZ - off) > nbyte)
n = nbyte & (SECSIZ - 1);