From 167206dea396ca5aa6147ca60c7dd6d6c1677e21 Mon Sep 17 00:00:00 2001
From: Stefano Garzarella <sgarzare@redhat.com>
Date: Thu, 29 Sep 2022 14:50:00 +0200
Subject: [PATCH] vsock: try to avoid panic as much as we can

Instead of panic, let's propagate errors or print warnings
where we can't.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 vsock/src/vhu_vsock.rs        | 16 ++++++++++------
 vsock/src/vhu_vsock_thread.rs | 23 +++++++++++++++++++----
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/vsock/src/vhu_vsock.rs b/vsock/src/vhu_vsock.rs
index 44bc8ef..84d1026 100644
--- a/vsock/src/vhu_vsock.rs
+++ b/vsock/src/vhu_vsock.rs
@@ -78,6 +78,8 @@ pub(crate) enum Error {
     HandleUnknownEvent,
     #[error("Failed to accept new local socket connection")]
     UnixAccept(std::io::Error),
+    #[error("Failed to bind a unix stream")]
+    UnixBind(std::io::Error),
     #[error("Failed to create an epoll fd")]
     EpollFdCreate(std::io::Error),
     #[error("Failed to add to epoll")]
@@ -118,6 +120,8 @@ pub(crate) enum Error {
     NoFreeLocalPort,
     #[error("Backend rx queue is empty")]
     EmptyBackendRxQ,
+    #[error("Failed to create an EventFd")]
+    EventFdCreate(std::io::Error),
 }
 
 impl std::convert::From<Error> for std::io::Error {
@@ -217,17 +221,17 @@ pub struct VhostUserVsockBackend {
 
 impl VhostUserVsockBackend {
     pub(crate) fn new(vsock_config: VsockConfig) -> Result<Self> {
-        let thread = Mutex::new(
-            VhostUserVsockThread::new(vsock_config.get_uds_path(), vsock_config.get_guest_cid())
-                .unwrap(),
-        );
+        let thread = Mutex::new(VhostUserVsockThread::new(
+            vsock_config.get_uds_path(),
+            vsock_config.get_guest_cid(),
+        )?);
         let queues_per_thread = vec![QUEUE_MASK];
 
         Ok(Self {
             guest_cid: vsock_config.get_guest_cid(),
             threads: vec![thread],
             queues_per_thread,
-            exit_event: EventFd::new(EFD_NONBLOCK).expect("Creating exit eventfd"),
+            exit_event: EventFd::new(EFD_NONBLOCK).map_err(Error::EventFdCreate)?,
         })
     }
 }
@@ -322,7 +326,7 @@ impl VhostUserBackendMut<VringRwLock, ()> for VhostUserVsockBackend {
     }
 
     fn exit_event(&self, _thread_index: usize) -> Option<EventFd> {
-        Some(self.exit_event.try_clone().expect("Cloning exit eventfd"))
+        self.exit_event.try_clone().ok()
     }
 }
 
diff --git a/vsock/src/vhu_vsock_thread.rs b/vsock/src/vhu_vsock_thread.rs
index 102c62a..c8bd267 100644
--- a/vsock/src/vhu_vsock_thread.rs
+++ b/vsock/src/vhu_vsock_thread.rs
@@ -41,6 +41,8 @@ pub struct VhostUserVsockThread {
     pub event_idx: bool,
     /// Host socket raw file descriptor.
     host_sock: RawFd,
+    /// Host socket path
+    host_sock_path: String,
     /// Listener listening for new connections on the host.
     host_listener: UnixListener,
     /// Used to kill the thread.
@@ -62,11 +64,11 @@ pub struct VhostUserVsockThread {
 impl VhostUserVsockThread {
     /// Create a new instance of VhostUserVsockThread.
     pub(crate) fn new(uds_path: String, guest_cid: u64) -> Result<Self> {
-        // TODO: better error handling
-        if let Ok(()) = std::fs::remove_file(uds_path.clone()) {}
+        // TODO: better error handling, maybe add a param to force the unlink
+        let _ = std::fs::remove_file(uds_path.clone());
         let host_sock = UnixListener::bind(&uds_path)
             .and_then(|sock| sock.set_nonblocking(true).map(|_| sock))
-            .unwrap();
+            .map_err(Error::UnixBind)?;
 
         let epoll_fd = epoll::create(true).map_err(Error::EpollFdCreate)?;
         let epoll_file = unsafe { File::from_raw_fd(epoll_fd) };
@@ -77,6 +79,7 @@ impl VhostUserVsockThread {
             mem: None,
             event_idx: false,
             host_sock: host_sock.as_raw_fd(),
+            host_sock_path: uds_path.clone(),
             host_listener: host_sock,
             kill_evt: EventFd::new(EFD_NONBLOCK).unwrap(),
             vring_worker: None,
@@ -205,7 +208,13 @@ impl VhostUserVsockThread {
                     // Has to be EPOLLIN as it was not connected previously
                     return;
                 }
-                let mut unix_stream = self.thread_backend.stream_map.remove(&fd).unwrap();
+                let mut unix_stream = match self.thread_backend.stream_map.remove(&fd) {
+                    Some(uds) => uds,
+                    None => {
+                        warn!("Error while searching fd in the stream map");
+                        return;
+                    }
+                };
 
                 // Local peer is sending a "connect PORT\n" command
                 let peer_port = match Self::read_local_stream_port(&mut unix_stream) {
@@ -572,3 +581,9 @@ impl VhostUserVsockThread {
         Ok(false)
     }
 }
+
+impl Drop for VhostUserVsockThread {
+    fn drop(&mut self) {
+        let _ = std::fs::remove_file(&self.host_sock_path);
+    }
+}