linux-kernel - Re: [PATCH RESEND v5] rust: str: Use `core::CStr`, remove the custom `CStr` implementation

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Message-ID: <9f55bb2d-f963-44f6-941c-2bf9923c8beb@proton.me>
Date: Wed, 21 Aug 2024 19:07:58 +0000
From: Benno Lossin <benno.lossin@...ton.me>
To: Alice Ryhl <aliceryhl@...gle.com>, Michal Rostecki <vadorovsky@...il.com>
Cc: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, Wedson Almeida Filho <wedsonaf@...il.com>, Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, Björn Roy Baron <bjorn3_gh@...tonmail.com>, Andreas Hindborg <a.hindborg@...sung.com>, Brendan Higgins <brendan.higgins@...ux.dev>, David Gow <davidgow@...gle.com>, Rae Moar <rmoar@...gle.com>, FUJITA Tomonori <fujita.tomonori@...il.com>, Trevor Gross <tmgross@...ch.edu>, Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>, Martin Rodriguez Reboredo <yakoyoku@...il.com>, Finn Behrens <me@...enk.dev>, Manmohan Shukla <manmshuk@...il.com>, Valentin Obst <kernel@...entinobst.de>, Yutaro Ohno <yutaro.ono.418@...il.com>, Asahi Lina <lina@...hilina.net>, Danilo Krummrich <dakr@...hat.com>, Tiago Lam <tiagolam@...il.com>, Charalampos Mitrodimas <charmitro@...teo.net>, Tejun Heo <tj@...nel.org>,
	Roland Xu <mu001999@...look.com>, rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org, kunit-dev@...glegroups.com, netdev@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH RESEND v5] rust: str: Use `core::CStr`, remove the custom `CStr` implementation

On 21.08.24 14:08, Alice Ryhl wrote:
> On Mon, Aug 19, 2024 at 5:39 PM Michal Rostecki <vadorovsky@...il.com> wrote:
>>
>> From: Michal Rostecki <vadorovsky@...il.com>
>>
>> `CStr` became a part of `core` library in Rust 1.75. This change replaces
>> the custom `CStr` implementation with the one from `core`.
>>
>> `core::CStr` behaves generally the same as the removed implementation,
>> with the following differences:
>>
>> - It does not implement `Display`.
>> - It does not provide `from_bytes_with_nul_unchecked_mut` method.
>> - It has `as_ptr()` method instead of `as_char_ptr()`, which also returns
>>   `*const c_char`.
>>
>> The first two differences are handled by providing the `CStrExt` trait,
>> with `display()` and `from_bytes_with_nul_unchecked_mut()` methods.
>> `display()` returns a `CStrDisplay` wrapper, with a custom `Display`
>> implementation.
>>
>> `DerefMut` implementation for `CString` is removed here, as it's not
>> being used anywhere.
>>
>> Signed-off-by: Michal Rostecki <vadorovsky@...il.com>
> 
> A few comments:
> 
> * I would probably add CStrExt to the kernel prelude.
> * I would probably remove `from_bytes_with_nul_unchecked_mut` and keep
> `DerefMut for CString` instead of the other way around.
> * Perhaps we should remove the `c_str!` macro and use c"" instead?

Read [1], it is needed, because there is no `c_stringify!` macro.

[1]: https://lore.kernel.org/rust-for-linux/52676577-372c-4a7f-aace-4cf100f93bfb@gmail.com/

---
Cheers,
Benno