gpt_gpt
if ((found = gpt_gpt(gpt, 1LL, 1)) == -1)
if (gpt_gpt(gpt, (off_t)lba, found) == -1)
if (gpt_gpt(gpt, devsz - 1LL, found) == -1)
int gpt_gpt(gpt_t, off_t, int);