linux/rust/kernel/sync/arc/std_vendor.rs
Asahi Lina 1edd03378e rust: sync: arc: Implement Arc<dyn Any + Send + Sync>::downcast()
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

Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Asahi Lina <lina@asahilina.net>
Link: https://lore.kernel.org/r/20230224-rust-arc-v2-1-5c97a865b276@asahilina.net
[ Moved `mod std_vendor;` up. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-04-10 23:55:43 +02:00

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Rust

// SPDX-License-Identifier: Apache-2.0 OR MIT
//! The contents of this file come from the Rust standard library, hosted in
//! the <https://github.com/rust-lang/rust> repository, licensed under
//! "Apache-2.0 OR MIT" and adapted for kernel use. For copyright details,
//! see <https://github.com/rust-lang/rust/blob/master/COPYRIGHT>.
use crate::sync::{arc::ArcInner, Arc};
use core::any::Any;
impl Arc<dyn Any + Send + Sync> {
/// Attempt to downcast the `Arc<dyn Any + Send + Sync>` to a concrete type.
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)
}
}
}