DockerCLI/vendor/github.com/Microsoft/hcsshim/internal/wclayer/legacy.go

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package wclayer
import (
"bufio"
"encoding/binary"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"strings"
"syscall"
"github.com/Microsoft/go-winio"
"github.com/Microsoft/hcsshim/internal/longpath"
"github.com/Microsoft/hcsshim/internal/safefile"
)
var errorIterationCanceled = errors.New("")
var mutatedUtilityVMFiles = map[string]bool{
`EFI\Microsoft\Boot\BCD`: true,
`EFI\Microsoft\Boot\BCD.LOG`: true,
`EFI\Microsoft\Boot\BCD.LOG1`: true,
`EFI\Microsoft\Boot\BCD.LOG2`: true,
}
const (
filesPath = `Files`
hivesPath = `Hives`
utilityVMPath = `UtilityVM`
utilityVMFilesPath = `UtilityVM\Files`
)
func openFileOrDir(path string, mode uint32, createDisposition uint32) (file *os.File, err error) {
return winio.OpenForBackup(path, mode, syscall.FILE_SHARE_READ, createDisposition)
}
func hasPathPrefix(p, prefix string) bool {
return strings.HasPrefix(p, prefix) && len(p) > len(prefix) && p[len(prefix)] == '\\'
}
type fileEntry struct {
path string
fi os.FileInfo
err error
}
type legacyLayerReader struct {
root string
result chan *fileEntry
proceed chan bool
currentFile *os.File
backupReader *winio.BackupFileReader
}
// newLegacyLayerReader returns a new LayerReader that can read the Windows
// container layer transport format from disk.
func newLegacyLayerReader(root string) *legacyLayerReader {
r := &legacyLayerReader{
root: root,
result: make(chan *fileEntry),
proceed: make(chan bool),
}
go r.walk()
return r
}
func readTombstones(path string) (map[string]([]string), error) {
tf, err := os.Open(filepath.Join(path, "tombstones.txt"))
if err != nil {
return nil, err
}
defer tf.Close()
s := bufio.NewScanner(tf)
if !s.Scan() || s.Text() != "\xef\xbb\xbfVersion 1.0" {
return nil, errors.New("Invalid tombstones file")
}
ts := make(map[string]([]string))
for s.Scan() {
t := filepath.Join(filesPath, s.Text()[1:]) // skip leading `\`
dir := filepath.Dir(t)
ts[dir] = append(ts[dir], t)
}
if err = s.Err(); err != nil {
return nil, err
}
return ts, nil
}
func (r *legacyLayerReader) walkUntilCancelled() error {
root, err := longpath.LongAbs(r.root)
if err != nil {
return err
}
r.root = root
ts, err := readTombstones(r.root)
if err != nil {
return err
}
err = filepath.Walk(r.root, func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
// Indirect fix for https://github.com/moby/moby/issues/32838#issuecomment-343610048.
// Handle failure from what may be a golang bug in the conversion of
// UTF16 to UTF8 in files which are left in the recycle bin. Os.Lstat
// which is called by filepath.Walk will fail when a filename contains
// unicode characters. Skip the recycle bin regardless which is goodness.
if strings.EqualFold(path, filepath.Join(r.root, `Files\$Recycle.Bin`)) && info.IsDir() {
return filepath.SkipDir
}
if path == r.root || path == filepath.Join(r.root, "tombstones.txt") || strings.HasSuffix(path, ".$wcidirs$") {
return nil
}
r.result <- &fileEntry{path, info, nil}
if !<-r.proceed {
return errorIterationCanceled
}
// List all the tombstones.
if info.IsDir() {
relPath, err := filepath.Rel(r.root, path)
if err != nil {
return err
}
if dts, ok := ts[relPath]; ok {
for _, t := range dts {
r.result <- &fileEntry{filepath.Join(r.root, t), nil, nil}
if !<-r.proceed {
return errorIterationCanceled
}
}
}
}
return nil
})
if err == errorIterationCanceled {
return nil
}
if err == nil {
return io.EOF
}
return err
}
func (r *legacyLayerReader) walk() {
defer close(r.result)
if !<-r.proceed {
return
}
err := r.walkUntilCancelled()
if err != nil {
for {
r.result <- &fileEntry{err: err}
if !<-r.proceed {
return
}
}
}
}
func (r *legacyLayerReader) reset() {
if r.backupReader != nil {
r.backupReader.Close()
r.backupReader = nil
}
if r.currentFile != nil {
r.currentFile.Close()
r.currentFile = nil
}
}
func findBackupStreamSize(r io.Reader) (int64, error) {
br := winio.NewBackupStreamReader(r)
for {
hdr, err := br.Next()
if err != nil {
if err == io.EOF {
err = nil
}
return 0, err
}
if hdr.Id == winio.BackupData {
return hdr.Size, nil
}
}
}
func (r *legacyLayerReader) Next() (path string, size int64, fileInfo *winio.FileBasicInfo, err error) {
r.reset()
r.proceed <- true
fe := <-r.result
if fe == nil {
err = errors.New("LegacyLayerReader closed")
return
}
if fe.err != nil {
err = fe.err
return
}
path, err = filepath.Rel(r.root, fe.path)
if err != nil {
return
}
if fe.fi == nil {
// This is a tombstone. Return a nil fileInfo.
return
}
if fe.fi.IsDir() && hasPathPrefix(path, filesPath) {
fe.path += ".$wcidirs$"
}
f, err := openFileOrDir(fe.path, syscall.GENERIC_READ, syscall.OPEN_EXISTING)
if err != nil {
return
}
defer func() {
if f != nil {
f.Close()
}
}()
fileInfo, err = winio.GetFileBasicInfo(f)
if err != nil {
return
}
if !hasPathPrefix(path, filesPath) {
size = fe.fi.Size()
r.backupReader = winio.NewBackupFileReader(f, false)
if path == hivesPath || path == filesPath {
// The Hives directory has a non-deterministic file time because of the
// nature of the import process. Use the times from System_Delta.
var g *os.File
g, err = os.Open(filepath.Join(r.root, hivesPath, `System_Delta`))
if err != nil {
return
}
attr := fileInfo.FileAttributes
fileInfo, err = winio.GetFileBasicInfo(g)
g.Close()
if err != nil {
return
}
fileInfo.FileAttributes = attr
}
// The creation time and access time get reset for files outside of the Files path.
fileInfo.CreationTime = fileInfo.LastWriteTime
fileInfo.LastAccessTime = fileInfo.LastWriteTime
} else {
// The file attributes are written before the backup stream.
var attr uint32
err = binary.Read(f, binary.LittleEndian, &attr)
if err != nil {
return
}
fileInfo.FileAttributes = attr
beginning := int64(4)
// Find the accurate file size.
if !fe.fi.IsDir() {
size, err = findBackupStreamSize(f)
if err != nil {
err = &os.PathError{Op: "findBackupStreamSize", Path: fe.path, Err: err}
return
}
}
// Return back to the beginning of the backup stream.
_, err = f.Seek(beginning, 0)
if err != nil {
return
}
}
r.currentFile = f
f = nil
return
}
func (r *legacyLayerReader) Read(b []byte) (int, error) {
if r.backupReader == nil {
if r.currentFile == nil {
return 0, io.EOF
}
return r.currentFile.Read(b)
}
return r.backupReader.Read(b)
}
func (r *legacyLayerReader) Seek(offset int64, whence int) (int64, error) {
if r.backupReader == nil {
if r.currentFile == nil {
return 0, errors.New("no current file")
}
return r.currentFile.Seek(offset, whence)
}
return 0, errors.New("seek not supported on this stream")
}
func (r *legacyLayerReader) Close() error {
r.proceed <- false
<-r.result
r.reset()
return nil
}
type pendingLink struct {
Path, Target string
TargetRoot *os.File
}
type pendingDir struct {
Path string
Root *os.File
}
type legacyLayerWriter struct {
root *os.File
destRoot *os.File
parentRoots []*os.File
currentFile *os.File
bufWriter *bufio.Writer
currentFileName string
currentFileRoot *os.File
backupWriter *winio.BackupFileWriter
Tombstones []string
HasUtilityVM bool
uvmDi []dirInfo
addedFiles map[string]bool
PendingLinks []pendingLink
pendingDirs []pendingDir
currentIsDir bool
}
// newLegacyLayerWriter returns a LayerWriter that can write the contaler layer
// transport format to disk.
func newLegacyLayerWriter(root string, parentRoots []string, destRoot string) (w *legacyLayerWriter, err error) {
w = &legacyLayerWriter{
addedFiles: make(map[string]bool),
}
defer func() {
if err != nil {
w.CloseRoots()
w = nil
}
}()
w.root, err = safefile.OpenRoot(root)
if err != nil {
return
}
w.destRoot, err = safefile.OpenRoot(destRoot)
if err != nil {
return
}
for _, r := range parentRoots {
f, err := safefile.OpenRoot(r)
if err != nil {
return w, err
}
w.parentRoots = append(w.parentRoots, f)
}
w.bufWriter = bufio.NewWriterSize(ioutil.Discard, 65536)
return
}
func (w *legacyLayerWriter) CloseRoots() {
if w.root != nil {
w.root.Close()
w.root = nil
}
if w.destRoot != nil {
w.destRoot.Close()
w.destRoot = nil
}
for i := range w.parentRoots {
w.parentRoots[i].Close()
}
w.parentRoots = nil
}
func (w *legacyLayerWriter) initUtilityVM() error {
if !w.HasUtilityVM {
err := safefile.MkdirRelative(utilityVMPath, w.destRoot)
if err != nil {
return err
}
// Server 2016 does not support multiple layers for the utility VM, so
// clone the utility VM from the parent layer into this layer. Use hard
// links to avoid unnecessary copying, since most of the files are
// immutable.
err = cloneTree(w.parentRoots[0], w.destRoot, utilityVMFilesPath, mutatedUtilityVMFiles)
if err != nil {
return fmt.Errorf("cloning the parent utility VM image failed: %s", err)
}
w.HasUtilityVM = true
}
return nil
}
func (w *legacyLayerWriter) reset() error {
err := w.bufWriter.Flush()
if err != nil {
return err
}
w.bufWriter.Reset(ioutil.Discard)
if w.currentIsDir {
r := w.currentFile
br := winio.NewBackupStreamReader(r)
// Seek to the beginning of the backup stream, skipping the fileattrs
if _, err := r.Seek(4, io.SeekStart); err != nil {
return err
}
for {
bhdr, err := br.Next()
if err == io.EOF {
// end of backupstream data
break
}
if err != nil {
return err
}
switch bhdr.Id {
case winio.BackupReparseData:
// The current file is a `.$wcidirs$` metadata file that
// describes a directory reparse point. Delete the placeholder
// directory to prevent future files being added into the
// destination of the reparse point during the ImportLayer call
if err := safefile.RemoveRelative(w.currentFileName, w.currentFileRoot); err != nil {
return err
}
w.pendingDirs = append(w.pendingDirs, pendingDir{Path: w.currentFileName, Root: w.currentFileRoot})
default:
// ignore all other stream types, as we only care about directory reparse points
}
}
w.currentIsDir = false
}
if w.backupWriter != nil {
w.backupWriter.Close()
w.backupWriter = nil
}
if w.currentFile != nil {
w.currentFile.Close()
w.currentFile = nil
w.currentFileName = ""
w.currentFileRoot = nil
}
return nil
}
// copyFileWithMetadata copies a file using the backup/restore APIs in order to preserve metadata
func copyFileWithMetadata(srcRoot, destRoot *os.File, subPath string, isDir bool) (fileInfo *winio.FileBasicInfo, err error) {
src, err := safefile.OpenRelative(
subPath,
srcRoot,
syscall.GENERIC_READ|winio.ACCESS_SYSTEM_SECURITY,
syscall.FILE_SHARE_READ,
safefile.FILE_OPEN,
safefile.FILE_OPEN_REPARSE_POINT)
if err != nil {
return nil, err
}
defer src.Close()
srcr := winio.NewBackupFileReader(src, true)
defer srcr.Close()
fileInfo, err = winio.GetFileBasicInfo(src)
if err != nil {
return nil, err
}
extraFlags := uint32(0)
if isDir {
extraFlags |= safefile.FILE_DIRECTORY_FILE
}
dest, err := safefile.OpenRelative(
subPath,
destRoot,
syscall.GENERIC_READ|syscall.GENERIC_WRITE|winio.WRITE_DAC|winio.WRITE_OWNER|winio.ACCESS_SYSTEM_SECURITY,
syscall.FILE_SHARE_READ,
safefile.FILE_CREATE,
extraFlags)
if err != nil {
return nil, err
}
defer dest.Close()
err = winio.SetFileBasicInfo(dest, fileInfo)
if err != nil {
return nil, err
}
destw := winio.NewBackupFileWriter(dest, true)
defer func() {
cerr := destw.Close()
if err == nil {
err = cerr
}
}()
_, err = io.Copy(destw, srcr)
if err != nil {
return nil, err
}
return fileInfo, nil
}
// cloneTree clones a directory tree using hard links. It skips hard links for
// the file names in the provided map and just copies those files.
func cloneTree(srcRoot *os.File, destRoot *os.File, subPath string, mutatedFiles map[string]bool) error {
var di []dirInfo
err := safefile.EnsureNotReparsePointRelative(subPath, srcRoot)
if err != nil {
return err
}
err = filepath.Walk(filepath.Join(srcRoot.Name(), subPath), func(srcFilePath string, info os.FileInfo, err error) error {
if err != nil {
return err
}
relPath, err := filepath.Rel(srcRoot.Name(), srcFilePath)
if err != nil {
return err
}
fileAttributes := info.Sys().(*syscall.Win32FileAttributeData).FileAttributes
// Directories, reparse points, and files that will be mutated during
// utility VM import must be copied. All other files can be hard linked.
isReparsePoint := fileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT != 0
// In go1.9, FileInfo.IsDir() returns false if the directory is also a symlink.
// See: https://github.com/golang/go/commit/1989921aef60c83e6f9127a8448fb5ede10e9acc
// Fixes the problem by checking syscall.FILE_ATTRIBUTE_DIRECTORY directly
isDir := fileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY != 0
if isDir || isReparsePoint || mutatedFiles[relPath] {
fi, err := copyFileWithMetadata(srcRoot, destRoot, relPath, isDir)
if err != nil {
return err
}
if isDir && !isReparsePoint {
di = append(di, dirInfo{path: relPath, fileInfo: *fi})
}
} else {
err = safefile.LinkRelative(relPath, srcRoot, relPath, destRoot)
if err != nil {
return err
}
}
return nil
})
if err != nil {
return err
}
return reapplyDirectoryTimes(destRoot, di)
}
func (w *legacyLayerWriter) Add(name string, fileInfo *winio.FileBasicInfo) error {
if err := w.reset(); err != nil {
return err
}
if name == utilityVMPath {
return w.initUtilityVM()
}
name = filepath.Clean(name)
if hasPathPrefix(name, utilityVMPath) {
if !w.HasUtilityVM {
return errors.New("missing UtilityVM directory")
}
if !hasPathPrefix(name, utilityVMFilesPath) && name != utilityVMFilesPath {
return errors.New("invalid UtilityVM layer")
}
createDisposition := uint32(safefile.FILE_OPEN)
if (fileInfo.FileAttributes & syscall.FILE_ATTRIBUTE_DIRECTORY) != 0 {
st, err := safefile.LstatRelative(name, w.destRoot)
if err != nil && !os.IsNotExist(err) {
return err
}
if st != nil {
// Delete the existing file/directory if it is not the same type as this directory.
existingAttr := st.Sys().(*syscall.Win32FileAttributeData).FileAttributes
if (uint32(fileInfo.FileAttributes)^existingAttr)&(syscall.FILE_ATTRIBUTE_DIRECTORY|syscall.FILE_ATTRIBUTE_REPARSE_POINT) != 0 {
if err = safefile.RemoveAllRelative(name, w.destRoot); err != nil {
return err
}
st = nil
}
}
if st == nil {
if err = safefile.MkdirRelative(name, w.destRoot); err != nil {
return err
}
}
if fileInfo.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT == 0 {
w.uvmDi = append(w.uvmDi, dirInfo{path: name, fileInfo: *fileInfo})
}
} else {
// Overwrite any existing hard link.
err := safefile.RemoveRelative(name, w.destRoot)
if err != nil && !os.IsNotExist(err) {
return err
}
createDisposition = safefile.FILE_CREATE
}
f, err := safefile.OpenRelative(
name,
w.destRoot,
syscall.GENERIC_READ|syscall.GENERIC_WRITE|winio.WRITE_DAC|winio.WRITE_OWNER|winio.ACCESS_SYSTEM_SECURITY,
syscall.FILE_SHARE_READ,
createDisposition,
safefile.FILE_OPEN_REPARSE_POINT,
)
if err != nil {
return err
}
defer func() {
if f != nil {
f.Close()
safefile.RemoveRelative(name, w.destRoot)
}
}()
err = winio.SetFileBasicInfo(f, fileInfo)
if err != nil {
return err
}
w.backupWriter = winio.NewBackupFileWriter(f, true)
w.bufWriter.Reset(w.backupWriter)
w.currentFile = f
w.currentFileName = name
w.currentFileRoot = w.destRoot
w.addedFiles[name] = true
f = nil
return nil
}
fname := name
if (fileInfo.FileAttributes & syscall.FILE_ATTRIBUTE_DIRECTORY) != 0 {
err := safefile.MkdirRelative(name, w.root)
if err != nil {
return err
}
fname += ".$wcidirs$"
w.currentIsDir = true
}
f, err := safefile.OpenRelative(fname, w.root, syscall.GENERIC_READ|syscall.GENERIC_WRITE, syscall.FILE_SHARE_READ, safefile.FILE_CREATE, 0)
if err != nil {
return err
}
defer func() {
if f != nil {
f.Close()
safefile.RemoveRelative(fname, w.root)
}
}()
strippedFi := *fileInfo
strippedFi.FileAttributes = 0
err = winio.SetFileBasicInfo(f, &strippedFi)
if err != nil {
return err
}
if hasPathPrefix(name, hivesPath) {
w.backupWriter = winio.NewBackupFileWriter(f, false)
w.bufWriter.Reset(w.backupWriter)
} else {
w.bufWriter.Reset(f)
// The file attributes are written before the stream.
err = binary.Write(w.bufWriter, binary.LittleEndian, uint32(fileInfo.FileAttributes))
if err != nil {
w.bufWriter.Reset(ioutil.Discard)
return err
}
}
w.currentFile = f
w.currentFileName = name
w.currentFileRoot = w.root
w.addedFiles[name] = true
f = nil
return nil
}
func (w *legacyLayerWriter) AddLink(name string, target string) error {
if err := w.reset(); err != nil {
return err
}
target = filepath.Clean(target)
var roots []*os.File
if hasPathPrefix(target, filesPath) {
// Look for cross-layer hard link targets in the parent layers, since
// nothing is in the destination path yet.
roots = w.parentRoots
} else if hasPathPrefix(target, utilityVMFilesPath) {
// Since the utility VM is fully cloned into the destination path
// already, look for cross-layer hard link targets directly in the
// destination path.
roots = []*os.File{w.destRoot}
}
if roots == nil || (!hasPathPrefix(name, filesPath) && !hasPathPrefix(name, utilityVMFilesPath)) {
return errors.New("invalid hard link in layer")
}
// Find to try the target of the link in a previously added file. If that
// fails, search in parent layers.
var selectedRoot *os.File
if _, ok := w.addedFiles[target]; ok {
selectedRoot = w.destRoot
} else {
for _, r := range roots {
if _, err := safefile.LstatRelative(target, r); err != nil {
if !os.IsNotExist(err) {
return err
}
} else {
selectedRoot = r
break
}
}
if selectedRoot == nil {
return fmt.Errorf("failed to find link target for '%s' -> '%s'", name, target)
}
}
// The link can't be written until after the ImportLayer call.
w.PendingLinks = append(w.PendingLinks, pendingLink{
Path: name,
Target: target,
TargetRoot: selectedRoot,
})
w.addedFiles[name] = true
return nil
}
func (w *legacyLayerWriter) Remove(name string) error {
name = filepath.Clean(name)
if hasPathPrefix(name, filesPath) {
w.Tombstones = append(w.Tombstones, name)
} else if hasPathPrefix(name, utilityVMFilesPath) {
err := w.initUtilityVM()
if err != nil {
return err
}
// Make sure the path exists; os.RemoveAll will not fail if the file is
// already gone, and this needs to be a fatal error for diagnostics
// purposes.
if _, err := safefile.LstatRelative(name, w.destRoot); err != nil {
return err
}
err = safefile.RemoveAllRelative(name, w.destRoot)
if err != nil {
return err
}
} else {
return fmt.Errorf("invalid tombstone %s", name)
}
return nil
}
func (w *legacyLayerWriter) Write(b []byte) (int, error) {
if w.backupWriter == nil && w.currentFile == nil {
return 0, errors.New("closed")
}
return w.bufWriter.Write(b)
}
func (w *legacyLayerWriter) Close() error {
if err := w.reset(); err != nil {
return err
}
if err := safefile.RemoveRelative("tombstones.txt", w.root); err != nil && !os.IsNotExist(err) {
return err
}
for _, pd := range w.pendingDirs {
err := safefile.MkdirRelative(pd.Path, pd.Root)
if err != nil {
return err
}
}
if w.HasUtilityVM {
err := reapplyDirectoryTimes(w.destRoot, w.uvmDi)
if err != nil {
return err
}
}
return nil
}