migrate to github.com/moby/go-archive module

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/github.com/moby/go-archive/archive_linux.go

@@ -0,0 +1,107 @@
+package archive
+
+import (
+	"archive/tar"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/moby/sys/userns"
+	"golang.org/x/sys/unix"
+)
+
+func getWhiteoutConverter(format WhiteoutFormat) tarWhiteoutConverter {
+	if format == OverlayWhiteoutFormat {
+		return overlayWhiteoutConverter{}
+	}
+	return nil
+}
+
+type overlayWhiteoutConverter struct{}
+
+func (overlayWhiteoutConverter) ConvertWrite(hdr *tar.Header, path string, fi os.FileInfo) (wo *tar.Header, _ error) {
+	// convert whiteouts to AUFS format
+	if fi.Mode()&os.ModeCharDevice != 0 && hdr.Devmajor == 0 && hdr.Devminor == 0 {
+		// we just rename the file and make it normal
+		dir, filename := filepath.Split(hdr.Name)
+		hdr.Name = filepath.Join(dir, WhiteoutPrefix+filename)
+		hdr.Mode = 0o600
+		hdr.Typeflag = tar.TypeReg
+		hdr.Size = 0
+	}
+
+	if fi.Mode()&os.ModeDir == 0 {
+		// FIXME(thaJeztah): return a sentinel error instead of nil, nil
+		return nil, nil
+	}
+
+	opaqueXattrName := "trusted.overlay.opaque"
+	if userns.RunningInUserNS() {
+		opaqueXattrName = "user.overlay.opaque"
+	}
+
+	// convert opaque dirs to AUFS format by writing an empty file with the prefix
+	opaque, err := lgetxattr(path, opaqueXattrName)
+	if err != nil {
+		return nil, err
+	}
+	if len(opaque) != 1 || opaque[0] != 'y' {
+		// FIXME(thaJeztah): return a sentinel error instead of nil, nil
+		return nil, nil
+	}
+	delete(hdr.PAXRecords, paxSchilyXattr+opaqueXattrName)
+
+	// create a header for the whiteout file
+	// it should inherit some properties from the parent, but be a regular file
+	return &tar.Header{
+		Typeflag:   tar.TypeReg,
+		Mode:       hdr.Mode & int64(os.ModePerm),
+		Name:       filepath.Join(hdr.Name, WhiteoutOpaqueDir), // #nosec G305 -- An archive is being created, not extracted.
+		Size:       0,
+		Uid:        hdr.Uid,
+		Uname:      hdr.Uname,
+		Gid:        hdr.Gid,
+		Gname:      hdr.Gname,
+		AccessTime: hdr.AccessTime,
+		ChangeTime: hdr.ChangeTime,
+	}, nil
+}
+
+func (c overlayWhiteoutConverter) ConvertRead(hdr *tar.Header, path string) (bool, error) {
+	base := filepath.Base(path)
+	dir := filepath.Dir(path)
+
+	// if a directory is marked as opaque by the AUFS special file, we need to translate that to overlay
+	if base == WhiteoutOpaqueDir {
+		opaqueXattrName := "trusted.overlay.opaque"
+		if userns.RunningInUserNS() {
+			opaqueXattrName = "user.overlay.opaque"
+		}
+
+		err := unix.Setxattr(dir, opaqueXattrName, []byte{'y'}, 0)
+		if err != nil {
+			return false, fmt.Errorf("setxattr('%s', %s=y): %w", dir, opaqueXattrName, err)
+		}
+		// don't write the file itself
+		return false, err
+	}
+
+	// if a file was deleted and we are using overlay, we need to create a character device
+	if strings.HasPrefix(base, WhiteoutPrefix) {
+		originalBase := base[len(WhiteoutPrefix):]
+		originalPath := filepath.Join(dir, originalBase)
+
+		if err := unix.Mknod(originalPath, unix.S_IFCHR, 0); err != nil {
+			return false, fmt.Errorf("failed to mknod('%s', S_IFCHR, 0): %w", originalPath, err)
+		}
+		if err := os.Chown(originalPath, hdr.Uid, hdr.Gid); err != nil {
+			return false, err
+		}
+
+		// don't write the file itself
+		return false, nil
+	}
+
+	return true, nil
+}