diff mbox series

[v1,10/28] rust: error: add `From` implementations for `Error`

Message ID 20221110164152.26136-11-ojeda@kernel.org
State New
Headers
Series Rust core additions |

Commit Message

Miguel Ojeda Nov. 10, 2022, 4:41 p.m. UTC 
  From: Wedson Almeida Filho <wedsonaf@gmail.com>

Add a set of `From` implementations for the `Error` kernel type.

These implementations allow to easily convert from standard Rust
error types to the usual kernel errors based on one of the `E*`
integer codes.

On top of that, the question mark Rust operator (`?`) implicitly
performs a conversion on the error value using the `From` trait
when propagating. Thus it is extra convenient to use.

For instance, a kernel function that needs to convert a `i64` into
a `i32` and to bubble up the error as a kernel error may write:

    fn f(x: i64) -> Result<...> {
        ...
        let y = i32::try_from(x)?;
        ...
    }

which will transform the `TryFromIntError` into an `Err(EINVAL)`.

Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com>
Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com>
Co-developed-by: Nándor István Krácser <bonifaido@gmail.com>
Signed-off-by: Nándor István Krácser <bonifaido@gmail.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
[Reworded, adapted for upstream and applied latest changes]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/error.rs | 45 +++++++++++++++++++++++++++++++++++++++++++-
 rust/kernel/lib.rs   |  1 +
 2 files changed, 45 insertions(+), 1 deletion(-)

Comments

Finn Behrens Nov. 11, 2022, 9:50 a.m. UTC | #1 
On 10 Nov 2022, at 17:41, Miguel Ojeda wrote:

> From: Wedson Almeida Filho <wedsonaf@gmail.com>
>
> Add a set of `From` implementations for the `Error` kernel type.
>
> These implementations allow to easily convert from standard Rust
> error types to the usual kernel errors based on one of the `E*`
> integer codes.
>
> On top of that, the question mark Rust operator (`?`) implicitly
> performs a conversion on the error value using the `From` trait
> when propagating. Thus it is extra convenient to use.
>
> For instance, a kernel function that needs to convert a `i64` into
> a `i32` and to bubble up the error as a kernel error may write:
>
>     fn f(x: i64) -> Result<...> {
>         ...
>         let y = i32::try_from(x)?;
>         ...
>     }
>
> which will transform the `TryFromIntError` into an `Err(EINVAL)`.
>
> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com>
> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com>
> Co-developed-by: Nándor István Krácser <bonifaido@gmail.com>
> Signed-off-by: Nándor István Krácser <bonifaido@gmail.com>
> Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
> [Reworded, adapted for upstream and applied latest changes]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Finn Behrens <me@kloenk.dev>

Regards,
Finn
> ---
>  rust/kernel/error.rs | 45 +++++++++++++++++++++++++++++++++++++++++++-
>  rust/kernel/lib.rs   |  1 +
>  2 files changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
> index 861746f2422d..5b9751d7ff1d 100644
> --- a/rust/kernel/error.rs
> +++ b/rust/kernel/error.rs
> @@ -4,7 +4,14 @@
>  //!
>  //! C header: [`include/uapi/asm-generic/errno-base.h`](../../../include/uapi/asm-generic/errno-base.h)
>
> -use alloc::collections::TryReserveError;
> +use alloc::{
> +    alloc::{AllocError, LayoutError},
> +    collections::TryReserveError,
> +};
> +
> +use core::convert::From;
> +use core::num::TryFromIntError;
> +use core::str::Utf8Error;
>
>  /// Contains the C-compatible error codes.
>  pub mod code {
> @@ -71,12 +78,48 @@ impl Error {
>      }
>  }
>
> +impl From<AllocError> for Error {
> +    fn from(_: AllocError) -> Error {
> +        code::ENOMEM
> +    }
> +}
> +
> +impl From<TryFromIntError> for Error {
> +    fn from(_: TryFromIntError) -> Error {
> +        code::EINVAL
> +    }
> +}
> +
> +impl From<Utf8Error> for Error {
> +    fn from(_: Utf8Error) -> Error {
> +        code::EINVAL
> +    }
> +}
> +
>  impl From<TryReserveError> for Error {
>      fn from(_: TryReserveError) -> Error {
>          code::ENOMEM
>      }
>  }
>
> +impl From<LayoutError> for Error {
> +    fn from(_: LayoutError) -> Error {
> +        code::ENOMEM
> +    }
> +}
> +
> +impl From<core::fmt::Error> for Error {
> +    fn from(_: core::fmt::Error) -> Error {
> +        code::EINVAL
> +    }
> +}
> +
> +impl From<core::convert::Infallible> for Error {
> +    fn from(e: core::convert::Infallible) -> Error {
> +        match e {}
> +    }
> +}
> +
>  /// A [`Result`] with an [`Error`] error type.
>  ///
>  /// To be used as the return type for functions that may fail.
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index abd46261d385..ffc6626a6d29 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -12,6 +12,7 @@
>  //! do so first instead of bypassing this crate.
>
>  #![no_std]
> +#![feature(allocator_api)]
>  #![feature(core_ffi_c)]
>
>  // Ensure conditional compilation based on the kernel configuration works;
> -- 
> 2.38.1
diff mbox series

Patch

diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 861746f2422d..5b9751d7ff1d 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -4,7 +4,14 @@ 
 //!
 //! C header: [`include/uapi/asm-generic/errno-base.h`](../../../include/uapi/asm-generic/errno-base.h)
 
-use alloc::collections::TryReserveError;
+use alloc::{
+    alloc::{AllocError, LayoutError},
+    collections::TryReserveError,
+};
+
+use core::convert::From;
+use core::num::TryFromIntError;
+use core::str::Utf8Error;
 
 /// Contains the C-compatible error codes.
 pub mod code {
@@ -71,12 +78,48 @@  impl Error {
     }
 }
 
+impl From<AllocError> for Error {
+    fn from(_: AllocError) -> Error {
+        code::ENOMEM
+    }
+}
+
+impl From<TryFromIntError> for Error {
+    fn from(_: TryFromIntError) -> Error {
+        code::EINVAL
+    }
+}
+
+impl From<Utf8Error> for Error {
+    fn from(_: Utf8Error) -> Error {
+        code::EINVAL
+    }
+}
+
 impl From<TryReserveError> for Error {
     fn from(_: TryReserveError) -> Error {
         code::ENOMEM
     }
 }
 
+impl From<LayoutError> for Error {
+    fn from(_: LayoutError) -> Error {
+        code::ENOMEM
+    }
+}
+
+impl From<core::fmt::Error> for Error {
+    fn from(_: core::fmt::Error) -> Error {
+        code::EINVAL
+    }
+}
+
+impl From<core::convert::Infallible> for Error {
+    fn from(e: core::convert::Infallible) -> Error {
+        match e {}
+    }
+}
+
 /// A [`Result`] with an [`Error`] error type.
 ///
 /// To be used as the return type for functions that may fail.
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index abd46261d385..ffc6626a6d29 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -12,6 +12,7 @@ 
 //! do so first instead of bypassing this crate.
 
 #![no_std]
+#![feature(allocator_api)]
 #![feature(core_ffi_c)]
 
 // Ensure conditional compilation based on the kernel configuration works;