builder/parallels: Add "DiskPath" driver function

This function determines path to the first virtual disk image of the specified virtual machine.

builder/parallels/common/driver.go

@@ -18,6 +18,9 @@ type Driver interface {
 	// Adds new CD/DVD drive to the VM and returns name of this device
 	DeviceAddCdRom(string, string) (string, error)
 
+	// Get path to the first virtual disk image
+	DiskPath(string) (string, error)
+
 	// Import a VM
 	Import(string, string, string, bool) error
 

builder/parallels/common/driver_9.go

@@ -121,6 +121,23 @@ func (d *Parallels9Driver) DeviceAddCdRom(name string, image string) (string, er
 	return device_name, nil
 }
 
+func (d *Parallels9Driver) DiskPath(name string) (string, error) {
+	out, err := exec.Command(d.PrlctlPath, "list", "-i", name).Output()
+	if err != nil {
+		return "", err
+	}
+
+	hddRe := regexp.MustCompile("hdd0.* image='(.*)' type=*")
+	matches := hddRe.FindStringSubmatch(string(out))
+	if matches == nil {
+		return "", fmt.Errorf(
+			"Could not determine hdd image path in the output:\n%s", string(out))
+	}
+
+	hdd_path := matches[1]
+	return hdd_path, nil
+}
+
 func (d *Parallels9Driver) IsRunning(name string) (bool, error) {
 	var stdout bytes.Buffer
 

builder/parallels/common/driver_mock.go

@@ -11,6 +11,11 @@ type DriverMock struct {
 	DeviceAddCdRomResult string
 	DeviceAddCdRomErr    error
 
+	DiskPathCalled bool
+	DiskPathName   string
+	DiskPathResult string
+	DiskPathErr    error
+
 	ImportCalled  bool
 	ImportName    string
 	ImportSrcPath string
@@ -61,6 +66,12 @@ func (d *DriverMock) DeviceAddCdRom(name string, image string) (string, error) {
 	return d.DeviceAddCdRomResult, d.DeviceAddCdRomErr
 }
 
+func (d *DriverMock) DiskPath(name string) (string, error) {
+	d.DiskPathCalled = true
+	d.DiskPathName = name
+	return d.DiskPathResult, d.DiskPathErr
+}
+
 func (d *DriverMock) Import(name, srcPath, dstPath string, reassignMac bool) error {
 	d.ImportCalled = true
 	d.ImportName = name