Struct multiboot2_common::DynSizedStructure

#[repr(C, align(8))]
pub struct DynSizedStructure<H: Header> { /* private fields */ }

An C ABI-compatible dynamically sized type with a common sized Header and a dynamic amount of bytes. This structures owns all its bytes, unlike Header. Instances guarantees that the memory requirements promised in the crates description are respected.

This can be a Multiboot2 header tag, information tag, boot information, or a Multiboot2 header. Depending on the context, the Header is different.

ABI

This type uses the C ABI. The fixed Header portion is always there. Further, there is a variable amount of payload bytes. Thus, this type can only exist on the heap or references to it can be made by cast via fat pointers.

Implementations

impl<H: Header> DynSizedStructure<H>

pub fn ref_from_bytes(bytes: BytesRef<'_, H>) -> Result<&Self, MemoryError>

Creates a new fat-pointer backed reference to a DynSizedStructure from the given BytesRef.

pub fn ref_from_slice(bytes: &[u8]) -> Result<&Self, MemoryError>

Creates a new fat-pointer backed reference to a DynSizedStructure from the given &[u8].

pub unsafe fn ref_from_ptr<'a>(ptr: NonNull<H>) -> Result<&'a Self, MemoryError>

Creates a new fat-pointer backed reference to a DynSizedStructure from the given thin pointer to the Header. It reads the total size from the header.

Safety

The caller must ensure that the function operates on valid memory.

pub const fn header(&self) -> &H

Returns the underlying Header.

pub const fn payload(&self) -> &[u8]

Returns the underlying payload.

pub fn cast<T: MaybeDynSized<Header = H> + ?Sized>(&self) -> &T

Casts the structure tag to a specific MaybeDynSized implementation which may be a ZST or DST typed tag. The output type will have the exact same size as *self. The target type must be sufficient for that. If not, the function will panic.

Safety

This function is safe due to various sanity checks and the overall memory assertions done while constructing this type.

Panics

This panics if there is a size mismatch. However, this should never be the case if all types follow their documented requirements.

Trait Implementations

impl<H: Debug + Header> Debug for DynSizedStructure<H>

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

Formats the value using the given formatter.

impl<H: Header> MaybeDynSized for DynSizedStructure<H>

type Header = H

The associated Header of this tag.

const BASE_SIZE: usize = _

The true base size of the struct without any implicit or additional padding. Note that size_of::<T>() isn’t sufficient, as for example the type could have three u32 fields, which would add an implicit u32 padding. However, this constant must always fulfill BASE_SIZE >= size_of::<Self::Header>().

fn dst_len(header: &Self::Header) -> Self::Metadata

Returns the amount of items in the dynamically sized portion of the DST. Note that this is not the amount of bytes. So if the dynamically sized portion is 16 bytes in size and each element is 4 bytes big, then this function must return 4.

fn header(&self) -> &Self::Header

Returns the corresponding Header.

fn payload(&self) -> &[u8]

Returns the payload, i.e., all memory that is not occupied by the Header of the type.

fn as_bytes(&self) -> BytesRef<'_, Self::Header>

Returns the whole allocated bytes for this structure encapsulated in BytesRef. This includes padding bytes. To only get the “true” tag data, read the tag size from Self::header and create a sub slice.

fn as_ptr(&self) -> *const Self::Header

Returns a pointer to this structure.

impl<H: PartialEq + Header> PartialEq for DynSizedStructure<H>

fn eq(&self, other: &DynSizedStructure<H>) -> 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<H: Header> Pointee for DynSizedStructure<H>

where [u8]: Pointee,

type Metadata = <[u8] as Pointee>::Metadata

The type for metadata in pointers and references to Self.

impl<H: Eq + Header> Eq for DynSizedStructure<H>

impl<H: Header> StructuralPartialEq for DynSizedStructure<H>