Function presser::read_at_offset_mut_unchecked
source · pub unsafe fn read_at_offset_mut_unchecked<'a, T, S: Slab + ?Sized>(
slab: &'a mut S,
offset: usize
) -> &'a mut T
Expand description
Gets a mutable reference to a T
within slab
at offset
, not checking any requirements.
offset
is the offset, in bytes, after the start ofslab
at which aT
is placed.
Safety
You must ensure:
offset
withinslab
is properly aligned forT
offset
is within bounds of theslab
offset + size_of::<T>
is within bounds of theslab
- You must have previously fully-initialized a valid
T
at the given offset intoslab
. If you want to fill an uninitialized buffer with data, you should instead use any of the copy helper functions or one of themaybe_uninit_mut
read functions.
Note that if you write through the returned reference, any padding bytes within the layout of T
(which for a repr(Rust)
type is arbitrary and unknown) must thereafter be considered uninitialized
until you explicitly initialize them again. This means that if you write a T
which contains
padding into slab
, you must not, for example, try to read those bytes as &[u8]
afterwards
(or as some other type which expects those bytes to be initialized), as you would then be
reading uninitialized memory, which is undefined behavior.
* Validity is a complex topic not to be taken lightly. See this rust reference page for more details.