Messages in this thread Patch in this message | | | From | Wedson Almeida Filho <> | Subject | [PATCH 4/5] rust: types: implement `ForeignOwnable` for the unit type | Date | Thu, 19 Jan 2023 14:40:35 -0300 |
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This allows us to use the unit type `()` when we have no object whose ownership must be managed but one implementing the `ForeignOwnable` trait is needed.
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com> --- rust/kernel/types.rs | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index e037c262f23e..8f80cffbff59 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -85,6 +85,19 @@ impl<T: 'static> ForeignOwnable for Box<T> { } } +impl ForeignOwnable for () { + type Borrowed<'a> = (); + + fn into_foreign(self) -> *const core::ffi::c_void { + // We use 1 to be different from a null pointer. + 1usize as _ + } + + unsafe fn borrow<'a>(_: *const core::ffi::c_void) -> Self::Borrowed<'a> {} + + unsafe fn from_foreign(_: *const core::ffi::c_void) -> Self {} +} + /// Runs a cleanup function/closure when dropped. /// /// The [`ScopeGuard::dismiss`] function prevents the cleanup function from running. -- 2.34.1
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