LCOW: Add platform to container, init on FromDisk()

Signed-off-by: John Howard <jhoward@microsoft.com>

container/container.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -77,6 +78,7 @@ type Container struct {
 	LogPath         string
 	Name            string
 	Driver          string
+	Platform        string
 	// MountLabel contains the options for the 'mount' command
 	MountLabel             string
 	ProcessLabel           string
@@ -142,6 +144,13 @@ func (container *Container) FromDisk() error {
 		return err
 	}
 
+	// Ensure the platform is set if blank. Assume it is the platform of the
+	// host OS if not, to ensure containers created before multiple-platform
+	// support are migrated
+	if container.Platform == "" {
+		container.Platform = runtime.GOOS
+	}
+
 	if err := label.ReserveLabel(container.ProcessLabel); err != nil {
 		return err
 	}