fatal("file %d: invalid cluster %08x\n", dent, cluster);
if (used[cluster])
fatal("file %d: duplicate cluster %08x also in file %d\n", dent, cluster, used[cluster]-1);
fatal("file %d: invalid cluster %08x\n", dent, cluster);
if (used[cluster])
fatal("file %d: duplicate cluster %08x also in file %d\n", dent, cluster, used[cluster]-1);