Replace AsSliceU8 trait with zerocopy::AsBytes.

Changed VirtioNetHdr to derive from AsBytes instead of AsSliceU8 and
changed related functions as necessary.

Fixes hermit-os#692.

Author: Joanne Chen

Cargo.lock

@@ -57,14 +57,14 @@ smp = ["include-transformed"]
 fsgsbase = []
 trace = []
 tcp = [
-    "async-task",
-    "futures-lite",
-    "smoltcp",
+	"async-task",
+	"futures-lite",
+	"smoltcp"
 ]
 dhcpv4 = [
-    "tcp",
-    "smoltcp/proto-dhcpv4",
-    "smoltcp/socket-dhcpv4",
+	"tcp",
+	"smoltcp/proto-dhcpv4",
+	"smoltcp/socket-dhcpv4"
 ]
 
 [dependencies]
@@ -90,6 +90,7 @@ lock_api = "0.4"
 num = { version = "0.4", default-features = false }
 num-traits = { version = "0.2", default-features = false }
 num-derive = "0.3"
+zerocopy = "0.6"
 
 [dependencies.smoltcp]
 version = "0.9"

Cargo.toml

@@ -11,6 +11,8 @@ use core::cmp::Ordering;
 use core::mem;
 use core::result::Result;
 
+use zerocopy::AsBytes;
+
 use self::constants::{FeatureSet, Features, NetHdrGSO, Status, MAX_NUM_VQ};
 use self::error::VirtioNetError;
 use crate::arch::kernel::core_local::increment_irq_counter;
@@ -25,7 +27,7 @@ use crate::drivers::virtio::transport::mmio::{ComCfg, IsrStatus, NotifCfg};
 #[cfg(feature = "pci")]
 use crate::drivers::virtio::transport::pci::{ComCfg, IsrStatus, NotifCfg};
 use crate::drivers::virtio::virtqueue::{
-	AsSliceU8, BuffSpec, BufferToken, Bytes, Transfer, Virtq, VqIndex, VqSize, VqType,
+	BuffSpec, BufferToken, Bytes, Transfer, Virtq, VqIndex, VqSize, VqType,
 };
 
 pub const ETH_HDR: usize = 14usize;
@@ -41,7 +43,7 @@ pub struct NetDevCfg {
 	pub features: FeatureSet,
 }
 
-#[derive(Debug)]
+#[derive(AsBytes, Debug)]
 #[repr(C)]
 pub struct VirtioNetHdr {
 	flags: u8,
@@ -58,9 +60,6 @@ pub struct VirtioNetHdr {
 	num_buffers: u16,
 }
 
-// Using the default implementation of the trait for VirtioNetHdr
-impl AsSliceU8 for VirtioNetHdr {}
-
 impl VirtioNetHdr {
 	pub fn get_tx_hdr() -> VirtioNetHdr {
 		VirtioNetHdr {

src/drivers/net/virtio_net.rs

@@ -21,6 +21,7 @@ use core::cell::RefCell;
 use core::ops::{BitAnd, Deref, DerefMut};
 
 use align_address::Align;
+use zerocopy::AsBytes;
 
 use self::error::{BufferError, VirtqError};
 use self::packed::PackedVq;
@@ -1683,15 +1684,15 @@ impl BufferToken {
 	///   * Will result in 4 bytes written to the second buffer descriptor of the recv buffer. Nothing is written into the second buffer descriptor.
 	/// * Third Write: `write_seq(Some(10 bytes, Some(4 bytes))`:
 	///   * Will result in 10 bytes written to the second buffer descriptor of the send buffer and 4 bytes written to the third buffer descriptor of the recv buffer.
-	pub fn write_seq<K: AsSliceU8, H: AsSliceU8 + ?Sized>(
+	pub fn write_seq<K: AsBytes, H: AsBytes + ?Sized>(
 		mut self,
 		send_seq: Option<&K>,
 		recv_seq: Option<&H>,
 	) -> Result<Self, VirtqError> {
 		if let Some(data) = send_seq {
 			match self.send_buff.as_mut() {
 				Some(buff) => {
-					match buff.next_write(data.as_slice_u8()) {
+					match buff.next_write(data.as_bytes()) {
 						Ok(_) => (), // Do nothing, write fitted inside descriptor and not to many writes to buffer happened
 						Err(_) => {
 							// Need no match here, as result is the same, but for the future one could
@@ -1707,7 +1708,7 @@ impl BufferToken {
 		if let Some(data) = recv_seq {
 			match self.recv_buff.as_mut() {
 				Some(buff) => {
-					match buff.next_write(data.as_slice_u8()) {
+					match buff.next_write(data.as_bytes()) {
 						Ok(_) => (), // Do nothing, write fitted inside descriptor and not to many writes to buffer happened
 						Err(_) => {
 							// Need no match here, as result is the same, but for the future one could