gpt_read
mbr = gpt_read(fd, 0LL, 1);
mbr = gpt_read(fd, lba, 1);
hdr = gpt_read(fd, lba, 1);
p = gpt_read(fd, le64toh(hdr->hdr_lba_table), blocks);
void* gpt_read(int, off_t, size_t);
buf = gpt_read(fd, start + LABELSECTOR32, 1);
dl = gpt_read(fd, start, roundup2(sizeof(*dl), secsz) / secsz);
mbr = gpt_read(fd, 0LL, 1);