Commit 03989773 authored by Wedson Almeida Filho's avatar Wedson Almeida Filho Committed by Miguel Ojeda
Browse files

rust: alloc: introduce the `VecExt` trait 



Make `try_with_capacity`, `try_push`, and `try_extend_from_slice`
methods available in `Vec` even though it doesn't implement them. It is
implemented with `try_reserve` and `push_within_capacity`.

This is in preparation for switching to the upstream `alloc` crate.

Reviewed-by: default avatarBenno Lossin <benno.lossin@proton.me>
Suggested-by: default avatarGary Guo <gary@garyguo.net>
Signed-off-by: default avatarWedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20240328013603.206764-3-wedsonaf@gmail.com


Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 31d94d8f

rust/kernel/alloc.rs

+1 −0
Original line number Diff line number Diff line
@@ -5,3 +5,4 @@ 
#[cfg(not(test))]

#[cfg(not(testlib))]

mod allocator;

pub mod vec_ext;

rust/kernel/alloc/vec_ext.rs

0 → 100644
+48 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



//! Extensions to [`Vec`] for fallible allocations.



use alloc::{collections::TryReserveError, vec::Vec};

use core::result::Result;



/// Extensions to [`Vec`].

pub trait VecExt<T>: Sized {

    /// Creates a new [`Vec`] instance with at least the given capacity.

    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError>;



    /// Appends an element to the back of the [`Vec`] instance.

    fn try_push(&mut self, v: T) -> Result<(), TryReserveError>;



    /// Pushes clones of the elements of slice into the [`Vec`] instance.

    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>

    where

        T: Clone;

}



impl<T> VecExt<T> for Vec<T> {

    fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {

        let mut v = Vec::new();

        v.try_reserve(capacity)?;

        Ok(v)

    }



    fn try_push(&mut self, v: T) -> Result<(), TryReserveError> {

        if let Err(retry) = self.push_within_capacity(v) {

            self.try_reserve(1)?;

            let _ = self.push_within_capacity(retry);

        }

        Ok(())

    }



    fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError>

    where

        T: Clone,

    {

        self.try_reserve(other.len())?;

        for item in other {

            self.try_push(item.clone())?;

        }



        Ok(())

    }

}

rust/kernel/lib.rs

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#![feature(new_uninit)]

#![feature(receiver_trait)]

#![feature(unsize)]

#![feature(vec_push_within_capacity)]



// Ensure conditional compilation based on the kernel configuration works;

// otherwise we may silently break things like initcall handling.

rust/kernel/prelude.rs

+2 −0
Original line number Diff line number Diff line
@@ -14,6 +14,8 @@ 
#[doc(no_inline)]

pub use core::pin::Pin;



pub use crate::alloc::vec_ext::VecExt;



#[doc(no_inline)]

pub use alloc::{boxed::Box, vec::Vec};