From 084d7ed082210a9a9716851b77817c1f4aa4a315 Mon Sep 17 00:00:00 2001
From: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Date: Mon, 11 Nov 2024 06:20:17 +0200
Subject: [PATCH] console: specify unknown event in HandleEventUnknown

Since we know the unknown event value, we might as well specify it in
the error message of Error::HandleEventUnknown to help users and
developers.

While at it, return an error when trying to access vrings with
`device_event` >= QUEUE_SIZE.

Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
---
 vhost-device-console/src/vhu_console.rs | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/vhost-device-console/src/vhu_console.rs b/vhost-device-console/src/vhu_console.rs
index 16a732e..a801a5b 100644
--- a/vhost-device-console/src/vhu_console.rs
+++ b/vhost-device-console/src/vhu_console.rs
@@ -63,8 +63,8 @@ type Result<T> = std::result::Result<T, Error>;
 
 #[derive(Copy, Clone, Debug, PartialEq, ThisError)]
 pub(crate) enum Error {
-    #[error("Failed to handle unknown event")]
-    HandleEventUnknown,
+    #[error("Failed to handle unknown event: {0}")]
+    HandleEventUnknown(u16),
     #[error("Descriptor not found")]
     DescriptorNotFound,
     #[error("Failed to send notification")]
@@ -351,9 +351,9 @@ impl VhostUserConsoleBackend {
             VIRTIO_CONSOLE_PORT_OPEN => {
                 trace!("VIRTIO_CONSOLE_PORT_OPEN");
             }
-            _ => {
-                trace!("Uknown control event");
-                return Err(Error::HandleEventUnknown);
+            other => {
+                trace!("Uknown control event: {}", other);
+                return Err(Error::HandleEventUnknown(other));
             }
         };
         Ok(())
@@ -742,8 +742,10 @@ impl VhostUserBackendMut for VhostUserConsoleBackend {
             &vrings[RX_QUEUE as usize]
         } else if device_event == BACKEND_CTRL_RX_EFD {
             &vrings[CTRL_RX_QUEUE as usize]
-        } else {
+        } else if (device_event as usize) < NUM_QUEUES {
             &vrings[device_event as usize]
+        } else {
+            return Err(Error::HandleEventUnknown(device_event).into());
         };
 
         if self.event_idx {
@@ -777,7 +779,7 @@ impl VhostUserBackendMut for VhostUserConsoleBackend {
                         let _ = self.rx_ctrl_event.read();
                         self.process_ctrl_rx_queue(vring)
                     }
-                    _ => Err(Error::HandleEventUnknown),
+                    other => Err(Error::HandleEventUnknown(other)),
                 }?;
                 if !vring.enable_notification().unwrap() {
                     break;
@@ -800,7 +802,7 @@ impl VhostUserBackendMut for VhostUserConsoleBackend {
                     let _ = self.rx_ctrl_event.read();
                     self.process_ctrl_rx_queue(vring)
                 }
-                _ => Err(Error::HandleEventUnknown),
+                other => Err(Error::HandleEventUnknown(other)),
             }?;
         }
         Ok(())
@@ -1097,7 +1099,7 @@ mod tests {
             vu_console_backend
                 .handle_control_msg(ctrl_msg_err)
                 .unwrap_err(),
-            Error::HandleEventUnknown
+            Error::HandleEventUnknown(4)
         );
 
         assert!(vu_console_backend.handle_control_msg(ctrl_msg_1).is_ok());