From: Wedson Almeida Filho <wedsonaf@gmail.com>

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_kernel_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@gmail.com>
Signed-off-by: Asahi Lina <lina@asahilina.net>
---
 rust/kernel/error.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 3b439fdb405c..1e8371f28746 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_kernel_errno(err))
+    } else {
+        Ok(())
+    }
+}

-- 
2.35.1

Asahi Lina <lina@asahilina.net> writes:

> From: Wedson Almeida Filho <wedsonaf@gmail.com>
>
> 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_kernel_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@gmail.com>
> Signed-off-by: Asahi Lina <lina@asahilina.net>
> ---

Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>

>  rust/kernel/error.rs | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
> index 3b439fdb405c..1e8371f28746 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_kernel_errno(err))
> +    } else {
> +        Ok(())
> +    }
> +}