queue: Ensure the use of Descriptor accessors

Ensure that we're using the Descriptor accessors everywhere, instead
of accessing its fields directly.

This is needed for the next commit, where we'll be fixing the
endianess of each field on its accessor.

Signed-off-by: Sergio Lopez <[email protected]>

Author: slp

crates/virtio-queue/src/lib.rs

@@ -138,7 +138,7 @@ impl Descriptor {
     /// If this is false, this descriptor is read only.
     /// Write only means the the emulated device can write and the driver can read.
     pub fn is_write_only(&self) -> bool {
-        self.flags & VIRTQ_DESC_F_WRITE != 0
+        self.flags() & VIRTQ_DESC_F_WRITE != 0
     }
 }
 
@@ -217,10 +217,10 @@ impl<M: GuestAddressSpace> DescriptorChain<M> {
             return Err(Error::InvalidIndirectDescriptor);
         }
 
-        let table_len = (desc.len as usize) / VIRTQ_DESCRIPTOR_SIZE;
+        let table_len = (desc.len() as usize) / VIRTQ_DESCRIPTOR_SIZE;
         // Check the target indirect descriptor table is correctly aligned.
         if desc.addr().raw_value() & (VIRTQ_DESCRIPTOR_SIZE as u64 - 1) != 0
-            || (desc.len as usize) & (VIRTQ_DESCRIPTOR_SIZE - 1) != 0
+            || (desc.len() as usize) & (VIRTQ_DESCRIPTOR_SIZE - 1) != 0
             || table_len > usize::from(u16::MAX)
         {
             return Err(Error::InvalidIndirectDescriptorTable);
@@ -1264,7 +1264,7 @@ mod tests {
             assert!(c.is_indirect);
             if i < 3 {
                 assert_eq!(desc.flags(), VIRTQ_DESC_F_NEXT);
-                assert_eq!(desc.next, i + 1);
+                assert_eq!(desc.next(), j + 1);
             }
         }
         // Even though we added a new descriptor after the one that is pointing to the indirect