Windows: Disable VM cloning for TP5 image

The Windows TP5 image is not compatible with the Hyper-V isolated
container clone feature. Detect old images and pass a flag specifying that
clone should not be enabled.

Signed-off-by: John Starks <jostarks@microsoft.com>

libcontainerd/client_windows.go

@@ -85,6 +85,13 @@ func (clnt *client) Create(containerID string, spec Spec, options ...CreateOptio
 		configuration.HvRuntime = &hcsshim.HvRuntime{
 			ImagePath: spec.Windows.HvRuntime.ImagePath,
 		}
+
+		// Images with build verison < 14350 don't support running with clone, but
+		// Windows cannot automatically detect this. Explicitly block cloning in this
+		// case.
+		if build := buildFromVersion(spec.Platform.OSVersion); build > 0 && build < 14350 {
+			configuration.HvRuntime.SkipTemplate = true
+		}
 	}
 
 	if configuration.HvPartition {

libcontainerd/process_windows.go

@@ -2,8 +2,6 @@ package libcontainerd
 
 import (
 	"io"
-	"strconv"
-	"strings"
 
 	"github.com/Microsoft/hcsshim"
 )
@@ -38,12 +36,7 @@ func fixStdinBackspaceBehavior(w io.WriteCloser, osversion string, tty bool) io.
 	if !tty {
 		return w
 	}
-	v := strings.Split(osversion, ".")
-	if len(v) < 3 {
-		return w
-	}
-
-	if build, err := strconv.Atoi(v[2]); err != nil || build >= 14350 {
+	if build := buildFromVersion(osversion); build == 0 || build >= 14350 {
 		return w
 	}
 

libcontainerd/utils_windows.go

@@ -1,6 +1,9 @@
 package libcontainerd
 
-import "strings"
+import (
+	"strconv"
+	"strings"
+)
 
 // setupEnvironmentVariables convert a string array of environment variables
 // into a map as required by the HCS. Source array is in format [v1=k1] [v2=k2] etc.
@@ -19,3 +22,16 @@ func setupEnvironmentVariables(a []string) map[string]string {
 func (s *ServicingOption) Apply(interface{}) error {
 	return nil
 }
+
+// buildFromVersion takes an image version string and returns the Windows build
+// number. It returns 0 if the build number is not present.
+func buildFromVersion(osver string) int {
+	v := strings.Split(osver, ".")
+	if len(v) < 3 {
+		return 0
+	}
+	if build, err := strconv.Atoi(v[2]); err == nil {
+		return build
+	}
+	return 0
+}