Re: [PATCH v2 4/6] rust: error: Add to_result() helper

[Gary Guo]

On Wed, 29 Mar 2023 21:04:36 +0900
Asahi Lina <lina@xxxxxxxxxxxxx> wrote:

> From: Wedson Almeida Filho <wedsonaf@xxxxxxxxx>
> 
> Add a to_result() helper to convert kernel C return values to a Rust
> Result, mapping >=0 values to Ok(()) and negative values to Err(...),
> with Error::from_errno() ensuring that the errno is within range.
> 
> Lina: Imported from rust-for-linux/rust, originally developed by Wedson
> as part of the AMBA device driver support.
> 
> Signed-off-by: Wedson Almeida Filho <wedsonaf@xxxxxxxxx>
> Reviewed-by: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
> Signed-off-by: Asahi Lina <lina@xxxxxxxxxxxxx>
> ---
>  rust/kernel/error.rs | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
> index 659468bd1735..4f599c4d1752 100644
> --- a/rust/kernel/error.rs
> +++ b/rust/kernel/error.rs
> @@ -167,3 +167,13 @@ impl From<core::convert::Infallible> for Error {
>  /// it should still be modeled as returning a `Result` rather than
>  /// just an [`Error`].
>  pub type Result<T = ()> = core::result::Result<T, Error>;
> +
> +/// Converts an integer as returned by a C kernel function to an error if it's negative, and
> +/// `Ok(())` otherwise.
> +pub fn to_result(err: core::ffi::c_int) -> Result {
> +    if err < 0 {
> +        Err(Error::from_errno(err))
> +    } else {
> +        Ok(())
> +    }
> +}
> 

Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>