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UEFI Allocator: Implement cores allocator_api #1632

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UEFI Allocator: Implement cores allocator_api #1632

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04e87f7
uefi: allocator: implement Allocator trait from allocator_api
phip1611 Apr 7, 2025
bb63cd3
uefi-test-runner: streamline
phip1611 Apr 19, 2025
ab4ddd1
uefi: Allocator: handle ZST
phip1611 Apr 19, 2025
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4 changes: 3 additions & 1 deletion uefi/CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,10 @@
- The `Display` impl for `CStr8` now excludes the trailing null character.
- `VariableKeys` initializes with a larger name buffer to work around firmware
bugs on some devices.
- The UEFI `allocator::Allocator` has been optimized for page-aligned
- The UEFI `allocator::Allocator` has been optimized for page-aligned
allocations.
- The UEFI `allocator::Allocator` now implements `core::alloc::Allocator`
(`allocator_api`), when the `unstable` feature is used.


# uefi - 0.34.1 (2025-02-07)
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14 changes: 14 additions & 0 deletions uefi/src/allocator.rs
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Expand Up @@ -169,3 +169,17 @@ unsafe impl GlobalAlloc for Allocator {
}
}
}

#[cfg(feature = "unstable")]
unsafe impl core::alloc::Allocator for Allocator {
fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, core::alloc::AllocError> {
let ptr = unsafe { <Allocator as GlobalAlloc>::alloc(self, layout) };
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Do we need to do something here to handle ZSTs? I'm not familiar with the details of the Allocator trait, but I noticed this in the documentation:

In contrast to GlobalAlloc, Allocator allows zero-sized allocations. If an underlying allocator does not support this (like jemalloc) or responds by returning a null pointer (such as libc::malloc), this must be caught by the implementation.

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Yes, I'm just not sure how to handle it :D but I can figure it out, I guess

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Nice use case but you're right. I added it in a dedicated commit

NonNull::new(ptr)
.ok_or(core::alloc::AllocError)
.map(|ptr| NonNull::slice_from_raw_parts(ptr, layout.size()))
}

unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
unsafe { <Allocator as GlobalAlloc>::dealloc(self, ptr.as_ptr(), layout) }
}
}
2 changes: 1 addition & 1 deletion uefi/src/lib.rs
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Expand Up @@ -212,7 +212,7 @@
//! [uefi-std-tr-issue]: https://github.com/rust-lang/rust/issues/100499
//! [unstable features]: https://doc.rust-lang.org/unstable-book/

#![cfg_attr(all(feature = "unstable", feature = "alloc"), feature(allocator_api))]
#![cfg_attr(feature = "unstable", feature(allocator_api))]
#![cfg_attr(docsrs, feature(doc_auto_cfg))]
#![no_std]
#![deny(
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