Commit b9ecf9b9 authored by Wedson Almeida Filho's avatar Wedson Almeida Filho Committed by Miguel Ojeda

rust: types: add `Opaque` type

Add the `Opaque` type, which is meant to be used with FFI objects
that are never interpreted by Rust code, e.g.:

    struct Waiter {
        completion: Opaque<bindings::completion>,
        next: *mut Waiter,
    }

It has the advantage that the objects don't have to be
zero-initialised before calling their init functions, making
the code performance closer to C.
Signed-off-by: default avatarWedson Almeida Filho <wedsonaf@gmail.com>
[Reworded, adapted for upstream and applied latest changes]
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent ba20915b
......@@ -2,6 +2,31 @@
//! Kernel types.
use core::{cell::UnsafeCell, mem::MaybeUninit};
/// Stores an opaque value.
///
/// This is meant to be used with FFI objects that are never interpreted by Rust code.
#[repr(transparent)]
pub struct Opaque<T>(MaybeUninit<UnsafeCell<T>>);
impl<T> Opaque<T> {
/// Creates a new opaque value.
pub const fn new(value: T) -> Self {
Self(MaybeUninit::new(UnsafeCell::new(value)))
}
/// Creates an uninitialised value.
pub const fn uninit() -> Self {
Self(MaybeUninit::uninit())
}
/// Returns a raw pointer to the opaque data.
pub fn get(&self) -> *mut T {
UnsafeCell::raw_get(self.0.as_ptr())
}
}
/// A sum type that always holds either a value of type `L` or `R`.
pub enum Either<L, R> {
/// Constructs an instance of [`Either`] containing a value of type `L`.
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment