[PATCH 2/3] rust: alloc: add Vec::resize method

Andrew Ballance
2025-03-15T02:43:26Z

implemnts the equivalent of the rust std's Vec::resize
on the kernel's Vec type.

Signed-off-by: Andrew Ballance <andrewjballance@gmail.com>
---
rust/kernel/alloc/kvec.rs | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs
index 75e9feebb81f..cbfef2e56f9c 100644
--- a/rust/kernel/alloc/kvec.rs
+++ b/rust/kernel/alloc/kvec.rs
@@ -554,6 +554,31 @@ pub fn from_elem(value: T, n: usize, flags: Flags) -> Result<Self, AllocError> {

Ok(v)
}
+
+ /// Resizes the [`Vec`] so that `len` is equal to `new_len`.
+ ///
+ /// If `new_len` is smaller than `len`, the `Vec` is [`Vec::truncate`]d.
+ /// If `new_len` is larger, each new slot is filled with clones of `value`.
+ ///
+ /// # Example
+ /// ```
+ /// let mut v = kernel::kvec![1, 2, 3]?;
+ /// v.resize(1, 42, GFP_KERNEL)?;
+ /// assert_eq!(&v, &[1]);
+ ///
+ /// v.resize(3, 42, GFP_KERNEL)?;
+ /// assert_eq!(&v, &[1, 42, 42]);
+ ///
+ /// # Ok::<(), Error>(())
+ /// ```
+ pub fn resize(&mut self, new_len: usize, value: T, flags: Flags) -> Result<(), AllocError> {
+ if new_len > self.len() {
+ self.extend_with(new_len - self.len(), value, flags)
+ } else {
+ self.truncate(new_len);
+ Ok(())
+ }
+ }
}

impl<T, A> Drop for Vec<T, A>
--
2.48.1