diff mbox series

[3/5] rust: types: implement `ForeignOwnable` for `Box<T>`

Message ID 20230119174036.64046-3-wedsonaf@gmail.com
State New
Headers
Series [1/5] rust: types: introduce `ScopeGuard` |

Commit Message

Wedson Almeida Filho Jan. 19, 2023, 5:40 p.m. UTC 
  This allows us to hand ownership of Rust dynamically allocated
objects to the C side of the kernel.

Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
---
 rust/kernel/types.rs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

Comments

Gary Guo Jan. 27, 2023, 1:56 p.m. UTC | #1 
On Thu, 19 Jan 2023 14:40:34 -0300
Wedson Almeida Filho <wedsonaf@gmail.com> wrote:

> This allows us to hand ownership of Rust dynamically allocated
> objects to the C side of the kernel.
> 
> Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/kernel/types.rs | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> index 5475f6163002..e037c262f23e 100644
> --- a/rust/kernel/types.rs
> +++ b/rust/kernel/types.rs
> @@ -63,6 +63,28 @@ pub trait ForeignOwnable {
>      unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self;
>  }
>  
> +impl<T: 'static> ForeignOwnable for Box<T> {
> +    type Borrowed<'a> = &'a T;
> +
> +    fn into_foreign(self) -> *const core::ffi::c_void {
> +        Box::into_raw(self) as _
> +    }
> +
> +    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
> +        // SAFETY: The safety requirements for this function ensure that the object is still alive,
> +        // so it is safe to dereference the raw pointer.
> +        // The safety requirements of `from_foreign` also ensure that the object remains alive for
> +        // the lifetime of the returned value.
> +        unsafe { &*ptr.cast() }
> +    }
> +
> +    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
> +        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
> +        // call to `Self::into_foreign`.
> +        unsafe { Box::from_raw(ptr as _) }
> +    }
> +}
> +
>  /// Runs a cleanup function/closure when dropped.
>  ///
>  /// The [`ScopeGuard::dismiss`] function prevents the cleanup function from running.
Vincenzo Palazzo Jan. 28, 2023, 10:50 a.m. UTC | #2 
On Thu Jan 19, 2023 at 6:40 PM CET, Wedson Almeida Filho wrote:
> This allows us to hand ownership of Rust dynamically allocated
> objects to the C side of the kernel.
>
> Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
> ---
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

>  1 file changed, 22 insertions(+)
>
> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> index 5475f6163002..e037c262f23e 100644
> --- a/rust/kernel/types.rs
> +++ b/rust/kernel/types.rs
> @@ -63,6 +63,28 @@ pub trait ForeignOwnable {
>      unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self;
>  }
>  
> +impl<T: 'static> ForeignOwnable for Box<T> {
> +    type Borrowed<'a> = &'a T;
> +
> +    fn into_foreign(self) -> *const core::ffi::c_void {
> +        Box::into_raw(self) as _
> +    }
> +
> +    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
> +        // SAFETY: The safety requirements for this function ensure that the object is still alive,
> +        // so it is safe to dereference the raw pointer.
> +        // The safety requirements of `from_foreign` also ensure that the object remains alive for
> +        // the lifetime of the returned value.
> +        unsafe { &*ptr.cast() }
> +    }
> +
> +    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
> +        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
> +        // call to `Self::into_foreign`.
> +        unsafe { Box::from_raw(ptr as _) }
> +    }
> +}
> +
>  /// Runs a cleanup function/closure when dropped.
>  ///
>  /// The [`ScopeGuard::dismiss`] function prevents the cleanup function from running.
> -- 
> 2.34.1
Alice Ferrazzi Jan. 30, 2023, 5:33 a.m. UTC | #3 
On Fri, Jan 20, 2023 at 2:41 AM Wedson Almeida Filho <wedsonaf@gmail.com> wrote:
>
> This allows us to hand ownership of Rust dynamically allocated
> objects to the C side of the kernel.
>
> Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
> ---

Reviewed-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com>
diff mbox series

Patch

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 5475f6163002..e037c262f23e 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -63,6 +63,28 @@  pub trait ForeignOwnable {
     unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self;
 }
 
+impl<T: 'static> ForeignOwnable for Box<T> {
+    type Borrowed<'a> = &'a T;
+
+    fn into_foreign(self) -> *const core::ffi::c_void {
+        Box::into_raw(self) as _
+    }
+
+    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
+        // SAFETY: The safety requirements for this function ensure that the object is still alive,
+        // so it is safe to dereference the raw pointer.
+        // The safety requirements of `from_foreign` also ensure that the object remains alive for
+        // the lifetime of the returned value.
+        unsafe { &*ptr.cast() }
+    }
+
+    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
+        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
+        // call to `Self::into_foreign`.
+        unsafe { Box::from_raw(ptr as _) }
+    }
+}
+
 /// Runs a cleanup function/closure when dropped.
 ///
 /// The [`ScopeGuard::dismiss`] function prevents the cleanup function from running.