Report its exit status from Wait() correctly

`err` was actually the variable outside of the goroutine.

Signed-off-by: Kazuyoshi Kato <[email protected]>

Author: kzys

machine.go

@@ -459,17 +459,19 @@ func (m *Machine) startVMM(ctx context.Context) error {
 
 	errCh := make(chan error)
 	go func() {
-		if err := m.cmd.Wait(); err != nil {
-			m.logger.Warnf("firecracker exited: %s", err.Error())
+		waitErr := m.cmd.Wait()
+		if waitErr != nil {
+			m.logger.Warnf("firecracker exited: %s", waitErr.Error())
 		} else {
 			m.logger.Printf("firecracker exited: status=0")
 		}
 
-		if err := m.doCleanup(); err != nil {
-			m.logger.Errorf("failed to cleanup after VM exit: %v", err)
+		cleanupErr := m.doCleanup()
+		if cleanupErr != nil {
+			m.logger.Errorf("failed to cleanup after VM exit: %v", cleanupErr)
 		}
 
-		errCh <- err
+		errCh <- multierror.Append(waitErr, cleanupErr).ErrorOrNil()
 
 		// Notify subscribers that there will be no more values.
 		// When err is nil, two reads are performed (waitForSocket and close exitCh goroutine),

machine_test.go

@@ -1075,3 +1075,55 @@ func TestCaptureFifoToFile_leak(t *testing.T) {
 	expected := `io.Copy failed to copy contents of fifo pipe: read testdata/TestCaptureFifoToFileLeak.fifo: file already closed`
 	assert.Contains(t, loggerBuffer.String(), expected)
 }
+
+func TestWait(t *testing.T) {
+	fctesting.RequiresRoot(t)
+	ctx := context.Background()
+
+	socketPath := filepath.Join(testDataPath, t.Name())
+	defer os.Remove(socketPath)
+
+	cfg := Config{
+		SocketPath:      socketPath,
+		KernelImagePath: getVmlinuxPath(t),
+		MachineCfg: models.MachineConfiguration{
+			VcpuCount:   Int64(2),
+			CPUTemplate: models.CPUTemplate(models.CPUTemplateT2),
+			MemSizeMib:  Int64(256),
+			HtEnabled:   Bool(false),
+		},
+		Drives: []models.Drive{
+			{
+				DriveID:      String("root"),
+				IsRootDevice: Bool(true),
+				IsReadOnly:   Bool(true),
+				PathOnHost:   String(testRootfs),
+			},
+		},
+	}
+
+	cmd := VMCommandBuilder{}.
+		WithSocketPath(cfg.SocketPath).
+		WithBin(getFirecrackerBinaryPath()).
+		Build(ctx)
+
+	m, err := NewMachine(ctx, cfg, WithProcessRunner(cmd))
+	require.NoError(t, err)
+
+	err = m.Start(ctx)
+	require.NoError(t, err)
+
+	go func() {
+		pid, err := m.PID()
+		require.NoError(t, err)
+
+		process, err := os.FindProcess(pid)
+		require.NoError(t, err)
+
+		err = process.Kill()
+		require.NoError(t, err)
+	}()
+
+	err = m.Wait(ctx)
+	require.Error(t, err, "Firecracker was killed and it must be reported")
+}