Add Validate method to VirtioDevice interface

- Use the newly added method to validate the devices
- Error out when qcow2 image is detected in block device validation

Author: vyasgun

cmd/vfkit/main.go

@@ -104,6 +104,10 @@ func newVMConfiguration(opts *cmdline.Options) (*config.VirtualMachine, error) {
 		return nil, err
 	}
 
+	if err := vmConfig.ValidateDevices(); err != nil {
+		return nil, err
+	}
+
 	if err := vmConfig.AddIgnitionFileFromCmdLine(opts.IgnitionPath); err != nil {
 		return nil, fmt.Errorf("failed to add ignition file: %w", err)
 	}

pkg/config/config.go

@@ -250,6 +250,15 @@ func (vm *VirtualMachine) AddIgnitionFileFromCmdLine(cmdlineOpts string) error {
 	return nil
 }
 
+func (vm *VirtualMachine) ValidateDevices() error {
+	for _, device := range vm.Devices {
+		if err := device.Validate(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func TimeSyncNew(vsockPort uint) (VMComponent, error) {
 
 	if vsockPort > math.MaxUint32 {

pkg/config/config_test.go

@@ -1,6 +1,9 @@
 package config
 
 import (
+	"os"
+	"os/exec"
+	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -44,3 +47,23 @@ func TestNetworkBlockDevice_NoDevice(t *testing.T) {
 	nbdItem := vm.NetworkBlockDevice("nbd2")
 	require.Nil(t, nbdItem)
 }
+
+func TestVirtualMachine_ValidateBlockDevices(t *testing.T) {
+	vm := &VirtualMachine{}
+
+	tmpDir := t.TempDir()
+	imagePath := filepath.Join(tmpDir, "disk.qcow2")
+	size := "1G"
+
+	cmd := exec.Command("qemu-img", "create", "-f", "qcow2", imagePath, size)
+	err := cmd.Run()
+	require.NoError(t, err)
+
+	dev, err := VirtioBlkNew(imagePath)
+	require.NoError(t, err)
+	vm.Devices = append(vm.Devices, dev)
+	defer os.Remove(imagePath)
+
+	err = vm.ValidateDevices()
+	require.Error(t, err)
+}

pkg/config/virtio.go

@@ -11,7 +11,10 @@ import (
 )
 
 // The VirtioDevice interface is an interface which is implemented by all virtio devices.
-type VirtioDevice VMComponent
+type VirtioDevice interface {
+	VMComponent
+	Validate() error
+}
 
 const (
 	// Possible values for VirtioInput.InputType
@@ -140,6 +143,10 @@ func (v *VirtioBalloon) ToCmdLine() ([]string, error) {
 	return []string{"--device", "virtio-balloon"}, nil
 }
 
+func (v *VirtioBalloon) Validate() error {
+	return nil
+}
+
 type option struct {
 	key   string
 	value string
@@ -230,7 +237,7 @@ func VirtioSerialNewStdio() (VirtioDevice, error) {
 	}, nil
 }
 
-func (dev *VirtioSerial) validate() error {
+func (dev *VirtioSerial) Validate() error {
 	if dev.LogFile != "" && dev.UsesStdio {
 		return fmt.Errorf("'logFilePath' and 'stdio' cannot be set at the same time")
 	}
@@ -242,7 +249,7 @@ func (dev *VirtioSerial) validate() error {
 }
 
 func (dev *VirtioSerial) ToCmdLine() ([]string, error) {
-	if err := dev.validate(); err != nil {
+	if err := dev.Validate(); err != nil {
 		return nil, err
 	}
 	if dev.UsesStdio {
@@ -267,7 +274,7 @@ func (dev *VirtioSerial) FromOptions(options []option) error {
 		}
 	}
 
-	return dev.validate()
+	return dev.Validate()
 }
 
 // VirtioInputNew creates a new input device for the virtual machine.
@@ -277,14 +284,14 @@ func VirtioInputNew(inputType string) (VirtioDevice, error) {
 	dev := &VirtioInput{
 		InputType: inputType,
 	}
-	if err := dev.validate(); err != nil {
+	if err := dev.Validate(); err != nil {
 		return nil, err
 	}
 
 	return dev, nil
 }
 
-func (dev *VirtioInput) validate() error {
+func (dev *VirtioInput) Validate() error {
 	if dev.InputType != VirtioInputPointingDevice && dev.InputType != VirtioInputKeyboardDevice {
 		return fmt.Errorf("unknown option for virtio-input devices: %s", dev.InputType)
 	}
@@ -293,7 +300,7 @@ func (dev *VirtioInput) validate() error {
 }
 
 func (dev *VirtioInput) ToCmdLine() ([]string, error) {
-	if err := dev.validate(); err != nil {
+	if err := dev.Validate(); err != nil {
 		return nil, err
 	}
 
@@ -312,7 +319,7 @@ func (dev *VirtioInput) FromOptions(options []option) error {
 			return fmt.Errorf("unknown option for virtio-input devices: %s", option.key)
 		}
 	}
-	return dev.validate()
+	return dev.Validate()
 }
 
 // VirtioGPUNew creates a new gpu device for the virtual machine.
@@ -328,7 +335,7 @@ func VirtioGPUNew() (VirtioDevice, error) {
 	}, nil
 }
 
-func (dev *VirtioGPU) validate() error {
+func (dev *VirtioGPU) Validate() error {
 	if dev.Height < 1 || dev.Width < 1 {
 		return fmt.Errorf("invalid dimensions for virtio-gpu device resolution: %dx%d", dev.Width, dev.Height)
 	}
@@ -337,7 +344,7 @@ func (dev *VirtioGPU) validate() error {
 }
 
 func (dev *VirtioGPU) ToCmdLine() ([]string, error) {
-	if err := dev.validate(); err != nil {
+	if err := dev.Validate(); err != nil {
 		return nil, err
 	}
 
@@ -371,7 +378,7 @@ func (dev *VirtioGPU) FromOptions(options []option) error {
 		dev.Height = defaultVirtioGPUResolutionHeight
 	}
 
-	return dev.validate()
+	return dev.Validate()
 }
 
 // VirtioNetNew creates a new network device for the virtual machine. It will
@@ -407,7 +414,7 @@ func (dev *VirtioNet) SetUnixSocketPath(path string) {
 	dev.Nat = false
 }
 
-func (dev *VirtioNet) validate() error {
+func (dev *VirtioNet) Validate() error {
 	if dev.Nat && dev.Socket != nil {
 		return fmt.Errorf("'nat' and 'fd' cannot be set at the same time")
 	}
@@ -425,7 +432,7 @@ func (dev *VirtioNet) validate() error {
 }
 
 func (dev *VirtioNet) ToCmdLine() ([]string, error) {
-	if err := dev.validate(); err != nil {
+	if err := dev.Validate(); err != nil {
 		return nil, err
 	}
 
@@ -474,7 +481,7 @@ func (dev *VirtioNet) FromOptions(options []option) error {
 		}
 	}
 
-	return dev.validate()
+	return dev.Validate()
 }
 
 // VirtioRngNew creates a new random number generator device to feed entropy
@@ -494,6 +501,10 @@ func (dev *VirtioRng) FromOptions(options []option) error {
 	return nil
 }
 
+func (dev *VirtioRng) Validate() error {
+	return nil
+}
+
 func nvmExpressControllerNewEmpty() *NVMExpressController {
 	return &NVMExpressController{
 		DiskStorageConfig: DiskStorageConfig{
@@ -551,6 +562,24 @@ func (dev *VirtioBlk) FromOptions(options []option) error {
 	return dev.DiskStorageConfig.FromOptions(unhandledOpts)
 }
 
+func (dev *VirtioBlk) Validate() error {
+	imgPath := dev.ImagePath
+	file, err := os.Open(imgPath)
+	if err != nil {
+		return fmt.Errorf("failed to open file %s: %v", imgPath, err)
+	}
+	defer file.Close()
+	header := make([]byte, 4)
+	_, err = file.Read(header)
+	if err != nil {
+		return fmt.Errorf("failed to read the header of file %s: %v", imgPath, err)
+	}
+	if string(header) == "QFI\xfb" {
+		return fmt.Errorf("vfkit does not support qcow2 image format")
+	}
+	return nil
+}
+
 func (dev *VirtioBlk) ToCmdLine() ([]string, error) {
 	cmdLine, err := dev.DiskStorageConfig.ToCmdLine()
 	if err != nil {
@@ -618,6 +647,10 @@ func (dev *VirtioVsock) FromOptions(options []option) error {
 	return nil
 }
 
+func (dev *VirtioVsock) Validate() error {
+	return nil
+}
+
 // VirtioFsNew creates a new virtio-fs device for file sharing. It will share
 // the directory at sharedDir with the virtual machine. This directory can be
 // mounted in the VM using `mount -t virtiofs mountTag /some/dir`
@@ -655,6 +688,10 @@ func (dev *VirtioFs) FromOptions(options []option) error {
 	return nil
 }
 
+func (dev *VirtioFs) Validate() error {
+	return nil
+}
+
 // RosettaShareNew RosettaShare creates a new rosetta share for running x86_64 binaries on M1 machines.
 // It will share a directory containing the linux rosetta binaries with the
 // virtual machine. This directory can be mounted in the VM using `mount -t
@@ -700,6 +737,10 @@ func (dev *RosettaShare) FromOptions(options []option) error {
 	return nil
 }
 
+func (dev *RosettaShare) Validate() error {
+	return nil
+}
+
 func networkBlockDeviceNewEmpty() *NetworkBlockDevice {
 	return &NetworkBlockDevice{
 		NetworkBlockStorageConfig: NetworkBlockStorageConfig{
@@ -778,6 +819,10 @@ func (nbd *NetworkBlockDevice) FromOptions(options []option) error {
 	return nbd.NetworkBlockStorageConfig.FromOptions(unhandledOpts)
 }
 
+func (nbd *NetworkBlockDevice) Validate() error {
+	return nil
+}
+
 type USBMassStorage struct {
 	DiskStorageConfig
 }
@@ -851,6 +896,10 @@ func (config *DiskStorageConfig) FromOptions(options []option) error {
 	return nil
 }
 
+func (config *DiskStorageConfig) Validate() error {
+	return nil
+}
+
 func (config *NetworkBlockStorageConfig) ToCmdLine() ([]string, error) {
 	if config.URI == "" {
 		return nil, fmt.Errorf("%s devices need the uri to a remote block device", config.DevName)