refactor: drop usage of std::io::Sink

This type is only useful if we are dynamically dispatching io via the
Read/Write traits, but we are not doing that (we converted everything to
static dispatch a while back, for better or for worse, and to avoid
conflicts with the PCI branch, I'm not reverting that here).

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

src/vmm/src/builder.rs

@@ -889,7 +889,7 @@ pub(crate) mod tests {
                     SerialEventsWrapper {
                         buffer_ready_event_fd: None,
                     },
-                    SerialOut::Sink(std::io::sink()),
+                    SerialOut::Sink,
                 ),
                 input: None,
             }))),

src/vmm/src/device_manager/legacy.rs

@@ -111,7 +111,7 @@ impl PortIODeviceManager {
                 SerialEventsWrapper {
                     buffer_ready_event_fd: None,
                 },
-                SerialOut::Sink(std::io::sink()),
+                SerialOut::Sink
             ),
             input: None,
         })));
@@ -121,7 +121,7 @@ impl PortIODeviceManager {
                 SerialEventsWrapper {
                     buffer_ready_event_fd: None,
                 },
-                SerialOut::Sink(std::io::sink()),
+                SerialOut::Sink
             ),
             input: None,
         })));
@@ -257,7 +257,7 @@ mod tests {
                     SerialEventsWrapper {
                         buffer_ready_event_fd: None,
                     },
-                    SerialOut::Sink(std::io::sink()),
+                    SerialOut::Sink,
                 ),
                 input: None,
             }))),

src/vmm/src/devices/legacy/serial.rs

@@ -125,19 +125,19 @@ impl SerialEvents for SerialEventsWrapper {
 
 #[derive(Debug)]
 pub enum SerialOut {
-    Sink(std::io::Sink),
+    Sink,
     Stdout(std::io::Stdout),
 }
 impl std::io::Write for SerialOut {
     fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
         match self {
-            Self::Sink(sink) => sink.write(buf),
+            Self::Sink => Ok(buf.len()),
             Self::Stdout(stdout) => stdout.write(buf),
         }
     }
     fn flush(&mut self) -> std::io::Result<()> {
         match self {
-            Self::Sink(sink) => sink.flush(),
+            Self::Sink => Ok(()),
             Self::Stdout(stdout) => stdout.flush(),
         }
     }
@@ -382,7 +382,7 @@ mod tests {
                 SerialEventsWrapper {
                     buffer_ready_event_fd: None,
                 },
-                SerialOut::Sink(std::io::sink()),
+                SerialOut::Sink,
             ),
             input: None::<std::io::Stdin>,
         };