Messages in this thread | | | Date | Sat, 25 Feb 2023 00:43:40 +0000 | From | Gary Guo <> | Subject | Re: [PATCH 1/2] rust: sync: arc: implement Arc<dyn Any + Send + Sync>::downcast() |
| |
On Fri, 24 Feb 2023 16:59:33 +0900 Asahi Lina <lina@asahilina.net> wrote:
> This mirrors the standard library's alloc::sync::Arc::downcast(). > > Based on the Rust standard library implementation, ver 1.62.0, > licensed under "Apache-2.0 OR MIT", from: > > https://github.com/rust-lang/rust/tree/1.62.0/library/alloc/src > > For copyright details, please see: > > https://github.com/rust-lang/rust/blob/1.62.0/COPYRIGHT > > Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
> --- > rust/kernel/sync/arc.rs | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs > index a94e303217c6..752bd7c4699e 100644 > --- a/rust/kernel/sync/arc.rs > +++ b/rust/kernel/sync/arc.rs > @@ -22,6 +22,7 @@ use crate::{ > }; > use alloc::boxed::Box; > use core::{ > + any::Any, > fmt, > marker::{PhantomData, Unsize}, > mem::{ManuallyDrop, MaybeUninit}, > @@ -220,6 +221,27 @@ impl<T: 'static> ForeignOwnable for Arc<T> { > } > } > > +impl Arc<dyn Any + Send + Sync> { > + /// Attempt to downcast the `Arc<dyn Any + Send + Sync>` to a concrete type. > + // Based on the Rust standard library implementation, ver 1.62.0, which is > + // Apache-2.0 OR MIT. > + pub fn downcast<T>(self) -> core::result::Result<Arc<T>, Self> > + where > + T: Any + Send + Sync, > + { > + if (*self).is::<T>() { > + // SAFETY: We have just checked that the type is correct, so we can cast the pointer. > + unsafe { > + let ptr = self.ptr.cast::<ArcInner<T>>(); > + core::mem::forget(self); > + Ok(Arc::from_inner(ptr)) > + } > + } else { > + Err(self) > + } > + } > +} > + > impl<T: ?Sized> Deref for Arc<T> { > type Target = T; > >
| |