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vendor/github.com/fsouza/go-dockerclient/internal/archive/archive_linux.go

@@ -0,0 +1,104 @@
+// Copyright 2014 Docker authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the DOCKER-LICENSE file.
+
+package archive
+
+import (
+	"archive/tar"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/docker/docker/pkg/system"
+	"golang.org/x/sys/unix"
+)
+
+const (
+	// AUFSWhiteoutFormat is the default format for whiteouts
+	AUFSWhiteoutFormat WhiteoutFormat = iota
+	// OverlayWhiteoutFormat formats whiteout according to the overlay
+	// standard.
+	OverlayWhiteoutFormat
+)
+
+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, err 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 = 0600
+		hdr.Typeflag = tar.TypeReg
+		hdr.Size = 0
+	}
+
+	if fi.Mode()&os.ModeDir != 0 {
+		// convert opaque dirs to AUFS format by writing an empty file with the prefix
+		opaque, err := system.Lgetxattr(path, "trusted.overlay.opaque")
+		if err != nil {
+			return nil, err
+		}
+		if len(opaque) == 1 && opaque[0] == 'y' {
+			if hdr.Xattrs != nil {
+				delete(hdr.Xattrs, "trusted.overlay.opaque")
+			}
+
+			// create a header for the whiteout file
+			// it should inherit some properties from the parent, but be a regular file
+			wo = &tar.Header{
+				Typeflag:   tar.TypeReg,
+				Mode:       hdr.Mode & int64(os.ModePerm),
+				Name:       filepath.Join(hdr.Name, WhiteoutOpaqueDir),
+				Size:       0,
+				Uid:        hdr.Uid,
+				Uname:      hdr.Uname,
+				Gid:        hdr.Gid,
+				Gname:      hdr.Gname,
+				AccessTime: hdr.AccessTime,
+				ChangeTime: hdr.ChangeTime,
+			}
+		}
+	}
+
+	return
+}
+
+func (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 {
+		err := unix.Setxattr(dir, "trusted.overlay.opaque", []byte{'y'}, 0)
+		// 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, 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
+}