From: Andreas Hindborg <a.hindborg@kernel.org>
Date: Thu, 27 Feb 2025 14:38:10 +0000 (+0100)
Subject: rust: str: implement `strip_prefix` for `BStr`
X-Git-Tag: v6.15-rc1~93^2~7
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5928642b11cb6aee8f6250c762857e713e7112da;p=thirdparty%2Fkernel%2Fstable.git

rust: str: implement `strip_prefix` for `BStr`

Implement `strip_prefix` for `BStr` by deferring to `slice::strip_prefix`
on the underlying `&[u8]`.

Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Tested-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
Tested-by: Daniel Gomez <da.gomez@samsung.com>
Link: https://lore.kernel.org/r/20250227-module-params-v3-v8-4-ceeee85d9347@kernel.org
[ Pluralized section name. Hid `use`. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index c6bd2c69543dc..878111cb77bc8 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -31,6 +31,23 @@ impl BStr {
         // SAFETY: `BStr` is transparent to `[u8]`.
         unsafe { &*(bytes as *const [u8] as *const BStr) }
     }
+
+    /// Strip a prefix from `self`. Delegates to [`slice::strip_prefix`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # 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: impl AsRef<Self>) -> Option<&BStr> {
+        self.deref()
+            .strip_prefix(pattern.as_ref().deref())
+            .map(Self::from_bytes)
+    }
 }
 
 impl fmt::Display for BStr {