The efi_alloc_and_init() function initializes the dk_gpt_t structure specified by vtoc in preparation for a call to efi_write(). It calculates and initializes the efi_version, efi_lbasize, efi_nparts, efi_first_u_lba, efi_last_lba, and efi_last_u_lba members of this sturcture. The caller can then set the efi_nparts member.

The efi_alloc_and_read() function allocates memory and returns the partition table.

The efi_free() function frees the memory allocated by efi_alloc_and_init() and efi_alloc_and_read().

The efi_write() function writes the EFI partition table.

The fd argument refers to any slice on a raw disk, opened with O_NDELAY. See open(2).

The nparts argument specifies the number of desired partitions.

The vtoc argument is a dk_gpt_t structure that describes an EFI partition table and contains at least the following members:

uint_t efi_version; /* set to EFI_VERSION_CURRENT */ uint_t efi_nparts; /* number of partitions in efi_parts */ uint_t efi_lbasize; /* size of block in bytes */ diskaddr_t efi_last_lba; /* last block on the disk */ diskaddr_t efi_first_u_lba; /* first block after labels */ diskaddr_t efi_last_u_lba; /* last block before backup labels */ struct dk_part efi_parts[]; /* array of partitions */

Upon successful completion, efi_alloc_and_init() returns 0. Otherwise it returns VT_EIO if an I/O operation to the disk fails.

Upon successful completion, efi_alloc_and_read() returns a positive integer indicating the slice index associated with the open file descriptor. Otherwise, it returns a negative integer to indicate one of the following:

VT_EIO

An I/O error occurred.

VT_ERROR

An unknown error occurred.

VT_EINVAL

An EFI label was not found.

Upon successful completion, efi_write() returns 0. Otherwise, it returns a negative integer to indicate one of the following:

VT_EIO

An I/O error occurred.

VT_ERROR

An unknown error occurred.

VT_EINVAL

The label contains incorrect data.

The EFI label is used on disks with more than 1³²-1 blocks. For compatibility reasons, the read_vtoc(3EXT) and write_vtoc() functions should be used on smaller disks. The application should attempt the read_vtoc() or write_vtoc() call, check for an error of VT_ENOTSUP, then call the analogous EFI function.

See attributes(5) for descriptions of the following attributes:

fmthard(1M), format(1M), prtvtoc(1M), ioctl(2), open(2), libefi(3LIB), read_vtoc(3EXT), attributes(5), dkio(7I)