| // SPDX-License-Identifier: GPL-2.0 |
| |
| //! Extensions to [`Box`] for fallible allocations. |
| |
| use super::{AllocError, Flags}; |
| use alloc::boxed::Box; |
| use core::mem::MaybeUninit; |
| |
| /// Extensions to [`Box`]. |
| pub trait BoxExt<T>: Sized { |
| /// Allocates a new box. |
| /// |
| /// The allocation may fail, in which case an error is returned. |
| fn new(x: T, flags: Flags) -> Result<Self, AllocError>; |
| |
| /// Allocates a new uninitialised box. |
| /// |
| /// The allocation may fail, in which case an error is returned. |
| fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>; |
| } |
| |
| impl<T> BoxExt<T> for Box<T> { |
| fn new(x: T, flags: Flags) -> Result<Self, AllocError> { |
| let b = <Self as BoxExt<_>>::new_uninit(flags)?; |
| Ok(Box::write(b, x)) |
| } |
| |
| #[cfg(any(test, testlib))] |
| fn new_uninit(_flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> { |
| Ok(Box::new_uninit()) |
| } |
| |
| #[cfg(not(any(test, testlib)))] |
| fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> { |
| let ptr = if core::mem::size_of::<MaybeUninit<T>>() == 0 { |
| core::ptr::NonNull::<_>::dangling().as_ptr() |
| } else { |
| let layout = core::alloc::Layout::new::<MaybeUninit<T>>(); |
| |
| // SAFETY: Memory is being allocated (first arg is null). The only other source of |
| // safety issues is sleeping on atomic context, which is addressed by klint. Lastly, |
| // the type is not a SZT (checked above). |
| let ptr = |
| unsafe { super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags) }; |
| if ptr.is_null() { |
| return Err(AllocError); |
| } |
| |
| ptr.cast::<MaybeUninit<T>>() |
| }; |
| |
| // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For |
| // zero-sized types, we use `NonNull::dangling`. |
| Ok(unsafe { Box::from_raw(ptr) }) |
| } |
| } |