Struct safer_ffi::ptr::NonNullRef

#[repr(transparent)]
pub struct NonNullRef<T>(pub NonNull<T>);

Implementations

impl<T> NonNullRef<T>

pub fn as_ptr(&self) -> *const T

pub fn cast<U>(self: NonNullRef<T>) -> NonNullRef<U>

Methods from Deref<Target = NonNull<T>>

pub unsafe fn as_uninit_ref<'a>(&self) -> &'a MaybeUninit<T>

🔬 This is a nightly-only experimental API. (ptr_as_uninit)

Returns a shared references to the value. In contrast to as_ref, this does not require that the value has to be initialized.

For the mutable counterpart see as_uninit_mut.

Safety

When calling this method, you have to ensure that all of the following is true:

• The pointer must be properly aligned.

• It must be “dereferencable” in the sense defined in the module documentation.

• You must enforce Rust’s aliasing rules, since the returned lifetime 'a is arbitrarily chosen and does not necessarily reflect the actual lifetime of the data. In particular, for the duration of this lifetime, the memory the pointer points to must not get mutated (except inside UnsafeCell).

This applies even if the result of this method is unused!

pub unsafe fn as_ref<'a>(&self) -> &'a T

Returns a shared reference to the value. If the value may be uninitialized, as_uninit_ref must be used instead.

For the mutable counterpart see as_mut.

Safety

When calling this method, you have to ensure that all of the following is true:

• The pointer must be properly aligned.

• It must be “dereferencable” in the sense defined in the module documentation.

• The pointer must point to an initialized instance of T.

• You must enforce Rust’s aliasing rules, since the returned lifetime 'a is arbitrarily chosen and does not necessarily reflect the actual lifetime of the data. In particular, for the duration of this lifetime, the memory the pointer points to must not get mutated (except inside UnsafeCell).

This applies even if the result of this method is unused! (The part about being initialized is not yet fully decided, but until it is, the only safe approach is to ensure that they are indeed initialized.)

pub unsafe fn as_uninit_slice<'a>(&self) -> &'a [MaybeUninit<T>]

🔬 This is a nightly-only experimental API. (ptr_as_uninit)

Returns a shared reference to a slice of possibly uninitialized values. In contrast to as_ref, this does not require that the value has to be initialized.

For the mutable counterpart see as_uninit_slice_mut.

Safety

When calling this method, you have to ensure that all of the following is true:

• The pointer must be valid for reads for ptr.len() * mem::size_of::<T>() many bytes, and it must be properly aligned. This means in particular:

  • The entire memory range of this slice must be contained within a single allocated object! Slices can never span across multiple allocated objects.

  • The pointer must be aligned even for zero-length slices. One reason for this is that enum layout optimizations may rely on references (including slices of any length) being aligned and non-null to distinguish them from other data. You can obtain a pointer that is usable as data for zero-length slices using NonNull::dangling().

• The total size ptr.len() * mem::size_of::<T>() of the slice must be no larger than isize::MAX. See the safety documentation of pointer::offset.

• You must enforce Rust’s aliasing rules, since the returned lifetime 'a is arbitrarily chosen and does not necessarily reflect the actual lifetime of the data. In particular, for the duration of this lifetime, the memory the pointer points to must not get mutated (except inside UnsafeCell).

This applies even if the result of this method is unused!

See also slice::from_raw_parts.

pub unsafe fn as_uninit_slice_mut<'a>(&self) -> &'a mut [MaybeUninit<T>]

🔬 This is a nightly-only experimental API. (ptr_as_uninit)

Returns a unique reference to a slice of possibly uninitialized values. In contrast to as_mut, this does not require that the value has to be initialized.

For the shared counterpart see as_uninit_slice.

Safety

When calling this method, you have to ensure that all of the following is true:

• The pointer must be valid for reads and writes for ptr.len() * mem::size_of::<T>() many bytes, and it must be properly aligned. This means in particular:

  • The entire memory range of this slice must be contained within a single allocated object! Slices can never span across multiple allocated objects.

  • The pointer must be aligned even for zero-length slices. One reason for this is that enum layout optimizations may rely on references (including slices of any length) being aligned and non-null to distinguish them from other data. You can obtain a pointer that is usable as data for zero-length slices using NonNull::dangling().

• The total size ptr.len() * mem::size_of::<T>() of the slice must be no larger than isize::MAX. See the safety documentation of pointer::offset.

• You must enforce Rust’s aliasing rules, since the returned lifetime 'a is arbitrarily chosen and does not necessarily reflect the actual lifetime of the data. In particular, for the duration of this lifetime, the memory the pointer points to must not get accessed (read or written) through any other pointer.

This applies even if the result of this method is unused!

See also slice::from_raw_parts_mut.

Examples

#![feature(allocator_api, ptr_as_uninit)]

use std::alloc::{Allocator, Layout, Global};
use std::mem::MaybeUninit;
use std::ptr::NonNull;

let memory: NonNull<[u8]> = Global.allocate(Layout::new::<[u8; 32]>())?;
// This is safe as `memory` is valid for reads and writes for `memory.len()` many bytes.
// Note that calling `memory.as_mut()` is not allowed here as the content may be uninitialized.
let slice: &mut [MaybeUninit<u8>] = unsafe { memory.as_uninit_slice_mut() };

Trait Implementations

impl<__> Clone for NonNullRef<__>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Debug for NonNullRef<T>

fn fmt(self: &NonNullRef<T>, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Deref for NonNullRef<T>

type Target = NonNull<T>

The resulting type after dereferencing.

fn deref(self: &NonNullRef<T>) -> &NonNull<T>

Dereferences the value.

impl<'lt, T: 'lt> From<&'lt T> for NonNullRef<T>

fn from(it: &'lt T) -> NonNullRef<T>

Performs the conversion.

impl<'lt, T: 'lt> From<&'lt mut T> for NonNullRef<T>

fn from(it: &'lt mut T) -> NonNullRef<T>

Performs the conversion.

impl<T> From<NonNull<T>> for NonNullRef<T>

fn from(it: NonNull<T>) -> Self

Performs the conversion.

impl<T: ReprC> ReprC for NonNullRef<T>

type CLayout = *const T::CLayout

The CType having the same layout as Self.

fn is_valid(it: &*const T::CLayout) -> bool

Sanity checks that can be performed on an instance of the CType layout.

impl<__> Copy for NonNullRef<__>