Implement `Borrow<T>` and `BorrowMut<T>` for `KBox<T>`. This allows
`KBox<T>` to be used in generic APIs asking for types implementing those
traits. `T` and `&mut T` also implement those traits allowing users to
use either owned, borrowed and heap-owned values.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
rust/kernel/alloc/kbox.rs | 61 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)
diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index c386ff771d506a2eb4c211a93ea9b59bc04c93f5..0e3cbe809a878766ee8f8508ed0d30b4f8afaa07 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -6,6 +6,7 @@
use super::allocator::{KVmalloc, Kmalloc, Vmalloc};
use super::{AllocError, Allocator, Flags};
use core::alloc::Layout;
+use core::borrow::{Borrow, BorrowMut};
use core::fmt;
use core::marker::PhantomData;
use core::mem::ManuallyDrop;
@@ -499,6 +500,66 @@ fn deref_mut(&mut self) -> &mut T {
}
}
+/// Allows `Box<T>` to be used as a `Borrow<T>`.
+///
+/// # Examples
+///
+/// ```
+/// # use core::borrow::Borrow;
+/// # use kernel::alloc::KBox;
+/// struct Foo<B: Borrow<u32>>(B);
+///
+/// // Owned instance.
+/// let foo_owned = Foo(1);
+///
+/// // Owned instance using `KBox`.
+/// let foo_box = Foo(KBox::new(1, GFP_KERNEL)?);
+///
+/// let i = 1;
+/// // Borrowed from `i`.
+/// let foo_borrowed = Foo(&i);
+/// # Ok::<(), Error>(())
+/// ```
+impl<T, A> Borrow<T> for Box<T, A>
+where
+ T: ?Sized,
+ A: Allocator,
+{
+ fn borrow(&self) -> &T {
+ self.deref()
+ }
+}
+
+/// Allows `Box<T>` to be used as a `BorrowMut<T>`.
+///
+/// # Examples
+///
+/// ```
+/// # use core::borrow::BorrowMut;
+/// # use kernel::alloc::KBox;
+/// struct Foo<B: BorrowMut<u32>>(B);
+///
+/// // Owned instance.
+/// let foo_owned = Foo(1);
+///
+/// // Owned instance using `KBox`.
+/// let foo_box = Foo(KBox::new(1, GFP_KERNEL)?);
+///
+/// let mut i = 1;
+/// // Borrowed from `i`.
+/// let foo_borrowed = Foo(&mut i);
+/// # Ok::<(), Error>(())
+/// ```
+impl<T, A> BorrowMut<T> for Box<T, A>
+where
+ T: ?Sized,
+ A: Allocator,
+{
+ fn borrow_mut(&mut self) -> &mut T {
+ self.deref_mut()
+ }
+}
+
impl<T, A> fmt::Display for Box<T, A>
where
T: ?Sized + fmt::Display,
--
2.49.0