Migrate to containerd 1.54

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/github.com/Microsoft/hcsshim/pkg/ociwclayer/export.go

@@ -0,0 +1,88 @@
+// Package ociwclayer provides functions for importing and exporting Windows
+// container layers from and to their OCI tar representation.
+package ociwclayer
+
+import (
+	"archive/tar"
+	"context"
+	"io"
+	"path/filepath"
+
+	"github.com/Microsoft/go-winio/backuptar"
+	"github.com/Microsoft/hcsshim"
+)
+
+var driverInfo = hcsshim.DriverInfo{}
+
+// ExportLayerToTar writes an OCI layer tar stream from the provided on-disk layer.
+// The caller must specify the parent layers, if any, ordered from lowest to
+// highest layer.
+//
+// The layer will be mounted for this process, so the caller should ensure that
+// it is not currently mounted.
+func ExportLayerToTar(ctx context.Context, w io.Writer, path string, parentLayerPaths []string) error {
+	err := hcsshim.ActivateLayer(driverInfo, path)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = hcsshim.DeactivateLayer(driverInfo, path)
+	}()
+
+	// Prepare and unprepare the layer to ensure that it has been initialized.
+	err = hcsshim.PrepareLayer(driverInfo, path, parentLayerPaths)
+	if err != nil {
+		return err
+	}
+	err = hcsshim.UnprepareLayer(driverInfo, path)
+	if err != nil {
+		return err
+	}
+
+	r, err := hcsshim.NewLayerReader(driverInfo, path, parentLayerPaths)
+	if err != nil {
+		return err
+	}
+
+	err = writeTarFromLayer(ctx, r, w)
+	cerr := r.Close()
+	if err != nil {
+		return err
+	}
+	return cerr
+}
+
+func writeTarFromLayer(ctx context.Context, r hcsshim.LayerReader, w io.Writer) error {
+	t := tar.NewWriter(w)
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+		}
+
+		name, size, fileInfo, err := r.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return err
+		}
+		if fileInfo == nil {
+			// Write a whiteout file.
+			hdr := &tar.Header{
+				Name: filepath.ToSlash(filepath.Join(filepath.Dir(name), whiteoutPrefix+filepath.Base(name))),
+			}
+			err := t.WriteHeader(hdr)
+			if err != nil {
+				return err
+			}
+		} else {
+			err = backuptar.WriteTarFileFromBackupStream(t, r, name, size, fileInfo)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return t.Close()
+}