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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.495, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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::() { > + 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::() != 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::() } { ([], mid, _) => mid.get(0), _ => None } (trick stolen from rust-vmm, in fact). Paolo