linux-kernel - Re: [PATCH v6 06/18] rust: str: add `bytes_to

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Message-ID: <87y0qyh9z4.fsf@t14s.mail-host-address-is-not-set>
Date: Mon, 01 Sep 2025 10:07:27 +0200
From: Andreas Hindborg <a.hindborg@...nel.org>
To: Daniel Almeida <daniel.almeida@...labora.com>
Cc: Boqun Feng <boqun.feng@...il.com>, Miguel Ojeda <ojeda@...nel.org>, Alex
 Gaynor <alex.gaynor@...il.com>, Gary Guo <gary@...yguo.net>, Björn Roy
 Baron <bjorn3_gh@...tonmail.com>, Benno Lossin <lossin@...nel.org>, Alice
 Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>, Danilo
 Krummrich <dakr@...nel.org>, Jens Axboe <axboe@...nel.dk>, Breno Leitao
 <leitao@...ian.org>, linux-block@...r.kernel.org,
 rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 06/18] rust: str: add `bytes_to_bool` helper function

"Daniel Almeida" <daniel.almeida@...labora.com> writes:

>> On 22 Aug 2025, at 09:14, Andreas Hindborg <a.hindborg@...nel.org> wrote:

<cut>

>> -    kernel::error::to_result(ret).map(|()| result)
>> +/// Convert `&[u8]` to `bool` by deferring to [`kernel::str::kstrtobool`].
>> +///
>> +/// Only considers at most the first two bytes of `bytes`.
>> +pub fn kstrtobool_bytes(bytes: &[u8]) -> Result<bool> {
>> +    // `ktostrbool` only considers the first two bytes of the input.
>> +    let stack_string = [*bytes.first().unwrap_or(&0), *bytes.get(1).unwrap_or(&0), 0];
>
> Can’t this be CStr::from_bytes_with_nul() ?
>
> This means that kstrtobool_raw could take a &CStr directly and thus not be unsafe IIUC?

By design, the input to this function need not be null terminated. My
use case is parsing the contents of a configfs file, and I would not
want to change the contents of the file, or allocate to create a null
terminated string, before calling this method.

We could add another function `kstrtobool_cstr` to do what you are
asking, but I think that could be a separate patch.


Best regards,
Andreas Hindborg