linux-kernel - Re: [PATCH v5 3/5] rust: str: implement `strip

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Message-ID: <CAH5fLgi-x6xT=xBV-Uv9do0tCaAOMOARZ5cigjsUBSyh2EJBOg@mail.gmail.com>
Date: Tue, 4 Feb 2025 13:50:20 +0100
From: Alice Ryhl <aliceryhl@...gle.com>
To: Andreas Hindborg <a.hindborg@...nel.org>
Cc: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
	Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
	Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
	Benno Lossin <benno.lossin@...ton.me>, Masahiro Yamada <masahiroy@...nel.org>, 
	Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nicolas@...sle.eu>, 
	Luis Chamberlain <mcgrof@...nel.org>, Trevor Gross <tmgross@...ch.edu>, 
	Adam Bratschi-Kaye <ark.email@...il.com>, rust-for-linux@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org, 
	Petr Pavlu <petr.pavlu@...e.com>, Sami Tolvanen <samitolvanen@...gle.com>, 
	Daniel Gomez <da.gomez@...sung.com>, Simona Vetter <simona.vetter@...ll.ch>, 
	Greg KH <gregkh@...uxfoundation.org>, linux-modules@...r.kernel.org
Subject: Re: [PATCH v5 3/5] rust: str: implement `strip_prefix` for `BStr`

On Tue, Feb 4, 2025 at 1:05 PM Andreas Hindborg <a.hindborg@...nel.org> wrote:
>
> Implement `strip_prefix` for `BStr` by deferring to `slice::strip_prefix`
> on the underlying `&[u8]`.
>
> Reviewed-by: Gary Guo <gary@...yguo.net>
> Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>
> Signed-off-by: Andreas Hindborg <a.hindborg@...nel.org>
> ---
>
> It is also possible to get this method by implementing
> `core::slice::SlicePattern` for `BStr`. `SlicePattern` is unstable, so this
> seems more reasonable.
> ---
>  rust/kernel/str.rs | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
> index 1eb945bed77d6592216cf30678fcca70d4c0b3b3..80601206961e5b2d682af5f7028434bba1604272 100644
> --- a/rust/kernel/str.rs
> +++ b/rust/kernel/str.rs
> @@ -31,6 +31,22 @@ pub const fn from_bytes(bytes: &[u8]) -> &Self {
>          // SAFETY: `BStr` is transparent to `[u8]`.
>          unsafe { &*(bytes as *const [u8] as *const BStr) }
>      }
> +
> +    /// Strip a prefix from `self`. Delegates to [`slice::strip_prefix`].
> +    ///
> +    /// # Example
> +    /// ```
> +    /// use kernel::b_str;
> +    /// assert_eq!(Some(b_str!("bar")), b_str!("foobar").strip_prefix(b_str!("foo")));
> +    /// assert_eq!(None, b_str!("foobar").strip_prefix(b_str!("bar")));
> +    /// assert_eq!(Some(b_str!("foobar")), b_str!("foobar").strip_prefix(b_str!("")));
> +    /// assert_eq!(Some(b_str!("")), b_str!("foobar").strip_prefix(b_str!("foobar")));
> +    /// ```
> +    pub fn strip_prefix(&self, pattern: &Self) -> Option<&BStr> {

Perhaps the pattern should just be &[u8]?

The code itself is fine, so
Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>

Alice