Crate presser

Utilities to help make copying data around into raw, possibly-uninitialized buffers easier and safer.

The main idea is to have Slab implemented on buffer-types for which it is safe to do, which then enables the use of the other functions within the crate.

See RawAllocation and BorrowedRawAllocation for built-in generic types that can be used to easily gain access to a type implementing Slab for a raw allocation or a custom buffer type.

Safety

Note that obeying the safety rules specified in the Slab safety documentation only guarantees safety for the direct results of the copy operations performed by the helper functions exported at the crate root (and the safe functions on Slab). However, it is not guaranteed that operations which would previously have been safe to perform using same backing memory that the Slab you copied into used are still safe.

For example, say you have a fully-initialized chunk of bytes (like a Vec<u8>), which you view as a Slab, and then (safely) perform a copy operation into using copy_to_offset. If the T you copied into it has any padding bytes in its memory layout, then the memory locations where those padding bytes now exist in the underlying Vec’s memory must now be treated as uninitialized. As such, taking any view into that byte vector which relies on those newly-uninit bytes being initialized to be valid (for example, taking a &[u8] slice of the Vec which includes those bytes, even if your code never actually reads from that slice) is now instant undefined behavior.

Structs

BorrowedRawAllocation

Represents the unique borrow of a contiguous piece of a single allocation with some layout that is used as a data copying destination. May be wholly or partially uninitialized.

CopyRecord

Record of the results of a copy operation

RawAllocation

Represents a contiguous piece of a single allocation with some layout. May be wholly or partially uninitialized.

Enums

CopyError

Traits

Slab

Represents a contiguous piece of a single allocation with some layout that is used as a data copying destination. May be wholly or partially uninitialized.

Functions

clone_into_maybe_uninit_slice

Clones the elements from src to dst, returning a mutable reference to the now initialized contents of dst. Any already initialized elements will not be dropped.

copy_from_iter_to_offset_with_align

Copies from src iterator into the memory represented by dst starting at a minimum location of start_offset bytes past the start of dst.

copy_from_iter_to_offset_with_align_packed

Like copy_from_iter_to_offset_with_align except that alignment between elements yielded by the iterator will ignore min_alignment and rather only be aligned to the alignment of T.

copy_from_slice_to_offset

Copies from slice into the memory represented by self starting at a minimum location of start_offset bytes past the start of self.

copy_from_slice_to_offset_with_align

Copies from slice into the memory represented by self starting at a minimum location of start_offset bytes past the start of self.

copy_into_maybe_uninit_slice

Copies the elements from src to dst, returning a mutable reference to the now initialized contents of dst.

copy_to_offset

Copies src into the memory represented by dst starting at a minimum location of start_offset bytes past the start of dst.

copy_to_offset_with_align

Copies src into the memory represented by dst starting at a minimum location of start_offset bytes past the start of dst and with minimum alignment min_alignment.

maybe_uninit_slice_from_vec^⚠

Takes a Vec and unsafely resizes it to the given length, returning a mutable slice to MaybeUninit<T> for each item in the newly-resized Vec.