vd_efi_alloc_and_read
if ((rv = vd_efi_alloc_and_read(&edev, &gpt, &gpe)) != 0) {
rv = vd_efi_alloc_and_read(&edev, &gpt, &gpe);
status = vd_efi_alloc_and_read(&edev, gpt, gpe);
int vd_efi_alloc_and_read(vd_efi_dev_t *dev, efi_gpt_t **gpt, efi_gpe_t **gpe);