linux-kernel - Re: [PATCH 4/5] rust: types: implement `ForeignOwnable` for the unit type

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <CQ3S2Z84SGAA.36ZVP0G4DF5VP@vincent>
Date:   Sat, 28 Jan 2023 12:14:29 +0100
From:   "Vincenzo Palazzo" <vincenzopalazzodev@...il.com>
To:     "Wedson Almeida Filho" <wedsonaf@...il.com>,
        <rust-for-linux@...r.kernel.org>
Cc:     "Miguel Ojeda" <ojeda@...nel.org>,
        "Alex Gaynor" <alex.gaynor@...il.com>,
        "Boqun Feng" <boqun.feng@...il.com>, "Gary Guo" <gary@...yguo.net>,
        Björn Roy Baron <bjorn3_gh@...tonmail.com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/5] rust: types: implement `ForeignOwnable` for the
 unit type

On Thu Jan 19, 2023 at 6:40 PM CET, Wedson Almeida Filho wrote:
> 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@...il.com>

Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@...il.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