containerd/archive/tar_windows.go

// +build windows

/*
   Copyright The containerd Authors.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package archive

import (
	"archive/tar"
	"bufio"
	"context"
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"

	"github.com/Microsoft/go-winio"
	"github.com/Microsoft/hcsshim"
	"github.com/containerd/containerd/sys"
)

const (
	// MSWINDOWS pax vendor extensions
	hdrMSWindowsPrefix = "MSWINDOWS."

	hdrFileAttributes        = hdrMSWindowsPrefix + "fileattr"
	hdrSecurityDescriptor    = hdrMSWindowsPrefix + "sd"
	hdrRawSecurityDescriptor = hdrMSWindowsPrefix + "rawsd"
	hdrMountPoint            = hdrMSWindowsPrefix + "mountpoint"
	hdrEaPrefix              = hdrMSWindowsPrefix + "xattr."

	// LIBARCHIVE pax vendor extensions
	hdrLibArchivePrefix = "LIBARCHIVE."

	hdrCreateTime = hdrLibArchivePrefix + "creationtime"
)

var (
	// mutatedFiles is a list of files that are mutated by the import process
	// and must be backed up and restored.
	mutatedFiles = map[string]string{
		"UtilityVM/Files/EFI/Microsoft/Boot/BCD":      "bcd.bak",
		"UtilityVM/Files/EFI/Microsoft/Boot/BCD.LOG":  "bcd.log.bak",
		"UtilityVM/Files/EFI/Microsoft/Boot/BCD.LOG1": "bcd.log1.bak",
		"UtilityVM/Files/EFI/Microsoft/Boot/BCD.LOG2": "bcd.log2.bak",
	}
)

// tarName returns platform-specific filepath
// to canonical posix-style path for tar archival. p is relative
// path.
func tarName(p string) (string, error) {
	// windows: convert windows style relative path with backslashes
	// into forward slashes. Since windows does not allow '/' or '\'
	// in file names, it is mostly safe to replace however we must
	// check just in case
	if strings.Contains(p, "/") {
		return "", fmt.Errorf("windows path contains forward slash: %s", p)
	}

	return strings.Replace(p, string(os.PathSeparator), "/", -1), nil
}

// chmodTarEntry is used to adjust the file permissions used in tar header based
// on the platform the archival is done.
func chmodTarEntry(perm os.FileMode) os.FileMode {
	perm &= 0755
	// Add the x bit: make everything +x from windows
	perm |= 0111

	return perm
}

func setHeaderForSpecialDevice(*tar.Header, string, os.FileInfo) error {
	// do nothing. no notion of Rdev, Inode, Nlink in stat on Windows
	return nil
}

func open(p string) (*os.File, error) {
	// We use sys.OpenSequential to ensure we use sequential file
	// access on Windows to avoid depleting the standby list.
	return sys.OpenSequential(p)
}

func openFile(name string, flag int, perm os.FileMode) (*os.File, error) {
	// Source is regular file. We use sys.OpenFileSequential to use sequential
	// file access to avoid depleting the standby list on Windows.
	return sys.OpenFileSequential(name, flag, perm)
}

func mkdirAll(path string, perm os.FileMode) error {
	return sys.MkdirAll(path, perm)
}

func mkdir(path string, perm os.FileMode) error {
	return os.Mkdir(path, perm)
}

func skipFile(hdr *tar.Header) bool {
	// Windows does not support filenames with colons in them. Ignore
	// these files. This is not a problem though (although it might
	// appear that it is). Let's suppose a client is running docker pull.
	// The daemon it points to is Windows. Would it make sense for the
	// client to be doing a docker pull Ubuntu for example (which has files
	// with colons in the name under /usr/share/man/man3)? No, absolutely
	// not as it would really only make sense that they were pulling a
	// Windows image. However, for development, it is necessary to be able
	// to pull Linux images which are in the repository.
	//
	// TODO Windows. Once the registry is aware of what images are Windows-
	// specific or Linux-specific, this warning should be changed to an error
	// to cater for the situation where someone does manage to upload a Linux
	// image but have it tagged as Windows inadvertently.
	return strings.Contains(hdr.Name, ":")
}

// handleTarTypeBlockCharFifo is an OS-specific helper function used by
// createTarFile to handle the following types of header: Block; Char; Fifo
func handleTarTypeBlockCharFifo(hdr *tar.Header, path string) error {
	return nil
}

func handleLChmod(hdr *tar.Header, path string, hdrInfo os.FileInfo) error {
	return nil
}

func getxattr(path, attr string) ([]byte, error) {
	return nil, nil
}

func setxattr(path, key, value string) error {
	// Return not support error, do not wrap underlying not supported
	// since xattrs should not exist in windows diff archives
	return errors.New("xattrs not supported on Windows")
}

// apply applies a tar stream of an OCI style diff tar of a Windows layer.
// See https://github.com/opencontainers/image-spec/blob/master/layer.md#applying-changesets
func apply(ctx context.Context, root string, tr *tar.Reader, options ApplyOptions) (size int64, err error) {
	if options.IsWindowsContainerLayer {
		return applyWindowsLayer(ctx, root, tr, options)
	}
	return applyNaive(ctx, root, tr, options)
}

// applyWindowsLayer applies a tar stream of an OCI style diff tar of a Windows layer.
// See https://github.com/opencontainers/image-spec/blob/master/layer.md#applying-changesets
func applyWindowsLayer(ctx context.Context, root string, tr *tar.Reader, options ApplyOptions) (size int64, err error) {
	home, id := filepath.Split(root)
	info := hcsshim.DriverInfo{
		HomeDir: home,
	}

	w, err := hcsshim.NewLayerWriter(info, id, options.ParentLayerPaths)
	if err != nil {
		return 0, err
	}
	defer func() {
		if err2 := w.Close(); err2 != nil {
			// This error should not be discarded as a failure here
			// could result in an invalid layer on disk
			if err == nil {
				err = err2
			}
		}
	}()

	buf := bufio.NewWriter(nil)
	hdr, nextErr := tr.Next()
	// Iterate through the files in the archive.
	for {
		select {
		case <-ctx.Done():
			return 0, ctx.Err()
		default:
		}

		if nextErr == io.EOF {
			// end of tar archive
			break
		}
		if nextErr != nil {
			return 0, nextErr
		}

		// Note: path is used instead of filepath to prevent OS specific handling
		// of the tar path
		base := path.Base(hdr.Name)
		if strings.HasPrefix(base, whiteoutPrefix) {
			dir := path.Dir(hdr.Name)
			originalBase := base[len(whiteoutPrefix):]
			originalPath := path.Join(dir, originalBase)
			if err := w.Remove(filepath.FromSlash(originalPath)); err != nil {
				return 0, err
			}
			hdr, nextErr = tr.Next()
		} else if hdr.Typeflag == tar.TypeLink {
			err := w.AddLink(filepath.FromSlash(hdr.Name), filepath.FromSlash(hdr.Linkname))
			if err != nil {
				return 0, err
			}
			hdr, nextErr = tr.Next()
		} else {
			name, fileSize, fileInfo, err := fileInfoFromHeader(hdr)
			if err != nil {
				return 0, err
			}
			if err := w.Add(filepath.FromSlash(name), fileInfo); err != nil {
				return 0, err
			}
			size += fileSize
			hdr, nextErr = tarToBackupStreamWithMutatedFiles(buf, w, tr, hdr, root)
		}
	}

	return
}

// fileInfoFromHeader retrieves basic Win32 file information from a tar header, using the additional metadata written by
// WriteTarFileFromBackupStream.
func fileInfoFromHeader(hdr *tar.Header) (name string, size int64, fileInfo *winio.FileBasicInfo, err error) {
	name = hdr.Name
	if hdr.Typeflag == tar.TypeReg || hdr.Typeflag == tar.TypeRegA {
		size = hdr.Size
	}
	fileInfo = &winio.FileBasicInfo{
		LastAccessTime: syscall.NsecToFiletime(hdr.AccessTime.UnixNano()),
		LastWriteTime:  syscall.NsecToFiletime(hdr.ModTime.UnixNano()),
		ChangeTime:     syscall.NsecToFiletime(hdr.ChangeTime.UnixNano()),

		// Default CreationTime to ModTime, updated below if MSWINDOWS.createtime exists
		CreationTime: syscall.NsecToFiletime(hdr.ModTime.UnixNano()),
	}
	if attrStr, ok := hdr.PAXRecords[hdrFileAttributes]; ok {
		attr, err := strconv.ParseUint(attrStr, 10, 32)
		if err != nil {
			return "", 0, nil, err
		}
		fileInfo.FileAttributes = uint32(attr)
	} else {
		if hdr.Typeflag == tar.TypeDir {
			fileInfo.FileAttributes |= syscall.FILE_ATTRIBUTE_DIRECTORY
		}
	}
	if createStr, ok := hdr.PAXRecords[hdrCreateTime]; ok {
		createTime, err := parsePAXTime(createStr)
		if err != nil {
			return "", 0, nil, err
		}
		fileInfo.CreationTime = syscall.NsecToFiletime(createTime.UnixNano())
	}
	return
}

// tarToBackupStreamWithMutatedFiles reads data from a tar stream and
// writes it to a backup stream, and also saves any files that will be mutated
// by the import layer process to a backup location.
func tarToBackupStreamWithMutatedFiles(buf *bufio.Writer, w io.Writer, t *tar.Reader, hdr *tar.Header, root string) (nextHdr *tar.Header, err error) {
	var (
		bcdBackup       *os.File
		bcdBackupWriter *winio.BackupFileWriter
	)
	if backupPath, ok := mutatedFiles[hdr.Name]; ok {
		bcdBackup, err = os.Create(filepath.Join(root, backupPath))
		if err != nil {
			return nil, err
		}
		defer func() {
			cerr := bcdBackup.Close()
			if err == nil {
				err = cerr
			}
		}()

		bcdBackupWriter = winio.NewBackupFileWriter(bcdBackup, false)
		defer func() {
			cerr := bcdBackupWriter.Close()
			if err == nil {
				err = cerr
			}
		}()

		buf.Reset(io.MultiWriter(w, bcdBackupWriter))
	} else {
		buf.Reset(w)
	}

	defer func() {
		ferr := buf.Flush()
		if err == nil {
			err = ferr
		}
	}()

	return writeBackupStreamFromTarFile(buf, t, hdr)
}

// writeBackupStreamFromTarFile writes a Win32 backup stream from the current tar file. Since this function may process multiple
// tar file entries in order to collect all the alternate data streams for the file, it returns the next
// tar file that was not processed, or io.EOF is there are no more.
func writeBackupStreamFromTarFile(w io.Writer, t *tar.Reader, hdr *tar.Header) (*tar.Header, error) {
	bw := winio.NewBackupStreamWriter(w)
	var sd []byte
	var err error
	// Maintaining old SDDL-based behavior for backward compatibility.  All new tar headers written
	// by this library will have raw binary for the security descriptor.
	if sddl, ok := hdr.PAXRecords[hdrSecurityDescriptor]; ok {
		sd, err = winio.SddlToSecurityDescriptor(sddl)
		if err != nil {
			return nil, err
		}
	}
	if sdraw, ok := hdr.PAXRecords[hdrRawSecurityDescriptor]; ok {
		sd, err = base64.StdEncoding.DecodeString(sdraw)
		if err != nil {
			return nil, err
		}
	}
	if len(sd) != 0 {
		bhdr := winio.BackupHeader{
			Id:   winio.BackupSecurity,
			Size: int64(len(sd)),
		}
		err := bw.WriteHeader(&bhdr)
		if err != nil {
			return nil, err
		}
		_, err = bw.Write(sd)
		if err != nil {
			return nil, err
		}
	}
	var eas []winio.ExtendedAttribute
	for k, v := range hdr.PAXRecords {
		if !strings.HasPrefix(k, hdrEaPrefix) {
			continue
		}
		data, err := base64.StdEncoding.DecodeString(v)
		if err != nil {
			return nil, err
		}
		eas = append(eas, winio.ExtendedAttribute{
			Name:  k[len(hdrEaPrefix):],
			Value: data,
		})
	}
	if len(eas) != 0 {
		eadata, err := winio.EncodeExtendedAttributes(eas)
		if err != nil {
			return nil, err
		}
		bhdr := winio.BackupHeader{
			Id:   winio.BackupEaData,
			Size: int64(len(eadata)),
		}
		err = bw.WriteHeader(&bhdr)
		if err != nil {
			return nil, err
		}
		_, err = bw.Write(eadata)
		if err != nil {
			return nil, err
		}
	}
	if hdr.Typeflag == tar.TypeSymlink {
		_, isMountPoint := hdr.PAXRecords[hdrMountPoint]
		rp := winio.ReparsePoint{
			Target:       filepath.FromSlash(hdr.Linkname),
			IsMountPoint: isMountPoint,
		}
		reparse := winio.EncodeReparsePoint(&rp)
		bhdr := winio.BackupHeader{
			Id:   winio.BackupReparseData,
			Size: int64(len(reparse)),
		}
		err := bw.WriteHeader(&bhdr)
		if err != nil {
			return nil, err
		}
		_, err = bw.Write(reparse)
		if err != nil {
			return nil, err
		}
	}

	buf := bufPool.Get().(*[]byte)
	defer bufPool.Put(buf)

	if hdr.Typeflag == tar.TypeReg || hdr.Typeflag == tar.TypeRegA {
		bhdr := winio.BackupHeader{
			Id:   winio.BackupData,
			Size: hdr.Size,
		}
		err := bw.WriteHeader(&bhdr)
		if err != nil {
			return nil, err
		}
		_, err = io.CopyBuffer(bw, t, *buf)
		if err != nil {
			return nil, err
		}
	}
	// Copy all the alternate data streams and return the next non-ADS header.
	for {
		ahdr, err := t.Next()
		if err != nil {
			return nil, err
		}
		if ahdr.Typeflag != tar.TypeReg || !strings.HasPrefix(ahdr.Name, hdr.Name+":") {
			return ahdr, nil
		}
		bhdr := winio.BackupHeader{
			Id:   winio.BackupAlternateData,
			Size: ahdr.Size,
			Name: ahdr.Name[len(hdr.Name):] + ":$DATA",
		}
		err = bw.WriteHeader(&bhdr)
		if err != nil {
			return nil, err
		}
		_, err = io.CopyBuffer(bw, t, *buf)
		if err != nil {
			return nil, err
		}
	}
}