fix: Refactor error propagation

Refactors error propagation to avoid logging and printing misleading
error messages.

Signed-off-by: Jonathan Woollett-Light <jcawl@amazon.co.uk>

src/firecracker/src/api_server_adapter.rs

@@ -52,7 +52,7 @@ impl ApiServerAdapter {
  vm_resources: VmResources,
  vmm: Arc<Mutex<Vmm>>,
  event_manager: &mut EventManager,
- ) -> FcExitCode {
+ ) -> Result<(), FcExitCode> {
  let api_adapter = Arc::new(Mutex::new(Self {
  api_event_fd,
  from_api,
@@ -64,10 +64,14 @@ impl ApiServerAdapter {
  event_manager
  .run()
  .expect("EventManager events driver fatal error");
- if let Some(exit_code) = vmm.lock().unwrap().shutdown_exit_code() {
- return exit_code;
+
+ match vmm.lock().unwrap().shutdown_exit_code() {
+ Some(FcExitCode::Ok) => break,
+ Some(exit_code) => return Err(exit_code),
+ None => continue,
  }
  }
+ Ok(())
  }
 
  fn handle_request(&mut self, req_action: VmmAction) {
@@ -245,7 +249,8 @@ pub(crate) fn run_with_api(
  api_thread.join().expect("Api thread should join");
 
  match result {
- Ok(exit_code) => Err(ApiServerError::MicroVMStoppedWithoutError(exit_code)),
+ Ok(Ok(())) => Ok(()),
+ Ok(Err(exit_code)) => Err(ApiServerError::MicroVMStoppedWithoutError(exit_code)),
  Err(exit_error) => Err(exit_error),
  }
 }

src/firecracker/src/main.rs

@@ -630,8 +630,11 @@ fn run_without_api(
  .run()
  .expect("Failed to start the event manager");
 
- if let Some(exit_code) = vmm.lock().unwrap().shutdown_exit_code() {
- return Err(RunWithoutApiError::Shutdown(exit_code));
+ match vmm.lock().unwrap().shutdown_exit_code() {
+ Some(FcExitCode::Ok) => break,
+ Some(exit_code) => return Err(RunWithoutApiError::Shutdown(exit_code)),
+ None => continue,
  }
  }
+ Ok(())
 }