Function presser::read_at_offset_mut
source · pub unsafe fn read_at_offset_mut<'a, T, S: Slab + ?Sized>(
slab: &'a mut S,
offset: usize
) -> Result<&'a mut T, Error>
Expand description
Gets a mutable reference to a T
within slab
at offset
.
offset
is the offset, in bytes, after the start ofslab
at which aT
is placed.
The function will return an error if:
offset
withinslab
is not properly aligned forT
offset
is out of bounds of theslab
offset + size_of::<T>
is out of bounds of theslab
Safety
You must have previously fully-initialized a valid* T
at the given offset into slab
. If you want to fill an uninitialized
buffer with data, you should instead use any of the copy helper functions or one of the maybe_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.