vm-virtio: Fix map_err losing the inner error

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vm-virtio/src/vsock/unix/mod.rs

@@ -28,12 +28,18 @@ mod defs {
 
 #[derive(Debug)]
 pub enum Error {
+    /// Error converting from UTF-8
+    ConvertFromUTF8(std::str::Utf8Error),
     /// Error registering a new epoll-listening FD.
     EpollAdd(std::io::Error),
     /// Error creating an epoll FD.
     EpollFdCreate(std::io::Error),
     /// The host made an invalid vsock port connection request.
     InvalidPortRequest,
+    /// Error parsing integer.
+    ParseInteger(std::num::ParseIntError),
+    /// Error reading stream port.
+    ReadStreamPort(Box<Error>),
     /// Error accepting a new connection from the host-side Unix socket.
     UnixAccept(std::io::Error),
     /// Error binding to the host-side Unix socket.

vm-virtio/src/vsock/unix/muxer.rs

@@ -452,7 +452,7 @@ impl VsockMuxer {
         }
 
         let mut word_iter = std::str::from_utf8(&buf[..blen])
-            .map_err(|_| Error::InvalidPortRequest)?
+            .map_err(Error::ConvertFromUTF8)?
             .split_whitespace();
 
         word_iter
@@ -466,8 +466,8 @@ impl VsockMuxer {
                 }
             })
             .and_then(|_| word_iter.next().ok_or(Error::InvalidPortRequest))
-            .and_then(|word| word.parse::<u32>().map_err(|_| Error::InvalidPortRequest))
+            .and_then(|word| word.parse::<u32>().map_err(Error::ParseInteger))
-            .map_err(|_| Error::InvalidPortRequest)
+            .map_err(|e| Error::ReadStreamPort(Box::new(e)))
     }
 
     /// Add a new connection to the active connection pool.