BLOCKALIGNMENT
disk.dk_size = strtonum(optarg, BLOCKALIGNMENT,
BLOCKALIGNMENT, UINT32_MAX);
blockoffset = BLOCKALIGNMENT;
if (start % BLOCKALIGNMENT)
start += (BLOCKALIGNMENT - start % BLOCKALIGNMENT);
if (start % BLOCKALIGNMENT)
start += (BLOCKALIGNMENT - start % BLOCKALIGNMENT);
if (needed % BLOCKALIGNMENT)
needed += (needed - (needed % BLOCKALIGNMENT));