Date:   Sat, 25 Feb 2023 22:19:21 +0000
From:   Gary Guo <gary@garyguo.net>
To:     Asahi Lina <lina@asahilina.net>
Cc:     Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        =?UTF-8?B?QmrDtnJu?= Roy Baron <bjorn3_gh@protonmail.com>,
        Sven Van Asbroeck <thesven73@gmail.com>,
        Fox Chen <foxhlchen@gmail.com>, rust-for-linux@vger.kernel.org,
        linux-kernel@vger.kernel.org, asahi@lists.linux.dev
Subject: Re: [PATCH 2/5] rust: error: Add Error::from_kernel_errno()
Message-ID: <20230225221921.4b4bc87d.gary@garyguo.net>
In-Reply-To: <20230224-rust-error-v1-2-f8f9a9a87303@asahilina.net>
References: <20230224-rust-error-v1-0-f8f9a9a87303@asahilina.net>
        <20230224-rust-error-v1-2-f8f9a9a87303@asahilina.net>
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On Fri, 24 Feb 2023 17:50:20 +0900
Asahi Lina <lina@asahilina.net> wrote:

> From: Miguel Ojeda <ojeda@kernel.org>
> 
> Add a function to create `Error` values out of a kernel error return,
> which safely upholds the invariant that the error code is well-formed
> (negative and greater than -MAX_ERRNO). If a malformed code is passed
> in, it will be converted to EINVAL.
> 
> Lina: Imported from rust-for-linux/rust as authored by Miguel and Fox
> with refactoring from Wedson.
> 
> Co-developed-by: Fox Chen <foxhlchen@gmail.com>
> Signed-off-by: Fox Chen <foxhlchen@gmail.com>
> Co-developed-by: Wedson Almeida Filho <wedsonaf@gmail.com>
> Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
> Signed-off-by: Asahi Lina <lina@asahilina.net>
> ---
>  rust/kernel/error.rs | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
> index 8611758e27f4..3b439fdb405c 100644
> --- a/rust/kernel/error.rs
> +++ b/rust/kernel/error.rs
> @@ -72,6 +72,25 @@ pub mod code {
>  pub struct Error(core::ffi::c_int);
>  
>  impl Error {
> +    /// Creates an [`Error`] from a kernel error code.
> +    ///
> +    /// It is a bug to pass an out-of-range `errno`. `EINVAL` would
> +    /// be returned in such a case.
> +    pub(crate) fn from_kernel_errno(errno: core::ffi::c_int) -> Error {

Maybe just `from_errno`? I don't know why `kernel` would need to be
emphasised here.

Best,
Gary