Struct Guid

#[repr(C, align(4))]
pub struct Guid { /* private fields */ }

Globally Unique Identifiers

The Guid type represents globally unique identifiers as defined by RFC-4122 (i.e., only the 10x variant is used), with the caveat that LE is used instead of BE.

Note that only the binary representation of Guids is stable. You are highly recommended to interpret Guids as 128bit integers.

The UEFI specification requires the type to be 64-bit aligned, yet EDK2 uses a mere 32-bit alignment. Hence, for compatibility, a 32-bit alignment is used.

UEFI uses the Microsoft-style Guid format. Hence, a lot of documentation and code refers to these Guids. If you thusly cannot treat Guids as 128-bit integers, this Guid type allows you to access the individual fields of the Microsoft-style Guid. A reminder of the Guid encoding:

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                          time_low                             |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |       time_mid                |         time_hi_and_version   |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |clk_seq_hi_res |  clk_seq_low  |         node (0-1)            |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                         node (2-5)                            |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The individual fields are encoded as little-endian. Accessors are provided for the Guid structure allowing access to these fields in native endian byte order.

Implementations

impl Guid

pub const fn from_fields( time_low: u32, time_mid: u16, time_hi_and_version: u16, clk_seq_hi_res: u8, clk_seq_low: u8, node: &[u8; 6], ) -> Guid

Initialize a Guid from its individual fields

This function initializes a Guid object given the individual fields as specified in the UEFI specification. That is, if you simply copy the literals from the specification into your code, this function will correctly initialize the Guid object.

In other words, this takes the individual fields in native endian and converts them to the correct endianness for a UEFI Guid.

Due to the fact that UEFI Guids use variant 2 of the UUID specification in a little-endian (or even mixed-endian) format, the following transformation is likely applied from text representation to binary representation:

00112233-4455-6677-8899-aabbccddeeff => 33 22 11 00 55 44 77 66 88 99 aa bb cc dd ee ff

(Note that UEFI protocols often use 88-99 instead of 8899) The first 3 parts use little-endian notation, the last 2 use big-endian.

pub const fn as_fields(&self) -> (u32, u16, u16, u8, u8, &[u8; 6])

Access a Guid as individual fields

This decomposes a Guid back into the individual fields as given in the specification. The individual fields are returned in native-endianness.

pub const fn from_bytes(bytes: &[u8; 16]) -> Self

Initialize a Guid from its byte representation

Create a new Guid object from its byte representation. This reinterprets the bytes as a Guid and copies them into a new Guid instance. Note that you can safely transmute instead.

See as_bytes() for the inverse operation.

pub const fn as_bytes(&self) -> &[u8; 16]

Access a Guid as raw byte array

This provides access to a Guid through a byte array. It is a simple re-interpretation of the Guid value as a 128-bit byte array. No conversion is performed. This is a simple cast.

Trait Implementations

impl Clone for Guid

fn clone(&self) -> Guid

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Guid

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for Guid

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Guid

fn cmp(&self, other: &Guid) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Guid

fn eq(&self, other: &Guid) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Guid

fn partial_cmp(&self, other: &Guid) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Guid

impl Eq for Guid

impl StructuralPartialEq for Guid