On 2/11/25 22:43, Kevin Wolf wrote:
+/// Implementing `SizedIoBuffer` provides an implementation for [`IoBuffer`]
without having to
+/// implement any functions manually.
+///
+/// # Safety
+///
+/// Types implementing `SizedIoBuffer` guarantee that the whole object can be
accessed as an I/O
+/// buffer that is safe to contain any byte patterns.
+pub unsafe trait SizedIoBuffer: Sized {
This is similar to the ByteValued trait in rust-vmm. Can you name it
the same so that we can later consider replacing it?
+ fn from_byte_slice(buf: &[u8]) -> Option<&Self> {
+ if buf.len() < std::mem::size_of::<Self>() {
+ return None;
+ }
+
+ let ptr = buf.as_ptr() as *const Self;
+
+ // TODO Use ptr.is_aligned() when MSRV is updated to at least 1.79.0
+ if (ptr as usize) % std::mem::align_of::<Self>() != 0 {
+ return None;
+ }
+
+ // SAFETY: This function checked that the byte slice is large enough
and aligned.
+ // Implementing SizedIoBuffer promises that any byte pattern is valid
for the type.
+ Some(unsafe { &*ptr })
If you want, the function can be written also
// SAFETY: implementing SizedIoBuffer promises that any byte pattern
// is valid for the type
match unsafe { buf.align_to::<Self>() } {
([], mid, _) => mid.get(0),
_ => None
}
(trick stolen from rust-vmm, in fact).
Paolo
