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legacy.go
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legacy.go
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package hcsshim
import (
"bufio"
"encoding/binary"
"errors"
"io"
"os"
"path/filepath"
"strings"
"syscall"
"github.com/Microsoft/go-winio"
)
var errorIterationCanceled = errors.New("")
func openFileOrDir(path string, mode uint32, createDisposition uint32) (file *os.File, err error) {
winPath, err := syscall.UTF16FromString(path)
if err != nil {
return
}
h, err := syscall.CreateFile(&winPath[0], mode, syscall.FILE_SHARE_READ, nil, createDisposition, syscall.FILE_FLAG_BACKUP_SEMANTICS, 0)
if err != nil {
err = &os.PathError{"open", path, err}
return
}
file = os.NewFile(uintptr(h), path)
return
}
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
isTP4Format bool
}
// NewLegacyLayerReader returns a new LayerReader that can read the Windows
// TP4 transport format from disk.
func NewLegacyLayerReader(root string) *LegacyLayerReader {
r := &LegacyLayerReader{
root: root,
result: make(chan *fileEntry),
proceed: make(chan bool),
isTP4Format: IsTP4(),
}
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 := 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) walk() {
defer close(r.result)
if !<-r.proceed {
return
}
ts, err := readTombstones(r.root)
if err != nil {
goto ErrorLoop
}
err = filepath.Walk(r.root, func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
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{t, nil, nil}
if !<-r.proceed {
return errorIterationCanceled
}
}
}
}
return nil
})
if err == errorIterationCanceled {
return
}
if err == nil {
err = io.EOF
}
ErrorLoop:
for {
r.result <- &fileEntry{err: err}
if !<-r.proceed {
break
}
}
}
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() && strings.HasPrefix(path, `Files\`) {
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 !strings.HasPrefix(path, `Files\`) {
size = fe.fi.Size()
r.backupReader = winio.NewBackupFileReader(f, false)
if path == "Hives" || path == "Files" {
// 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, `Hives\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 {
beginning := int64(0)
if !r.isTP4Format {
// In TP5, the file attributes were added before the backup stream
var attr uint32
err = binary.Read(f, binary.LittleEndian, &attr)
if err != nil {
return
}
fileInfo.FileAttributes = uintptr(attr)
beginning = 4
}
// Find the accurate file size.
if !fe.fi.IsDir() {
size, err = findBackupStreamSize(f)
if err != nil {
err = &os.PathError{"findBackupStreamSize", fe.path, 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) Close() error {
r.proceed <- false
<-r.result
r.reset()
return nil
}
type LegacyLayerWriter struct {
root string
currentFile *os.File
backupWriter *winio.BackupFileWriter
tombstones []string
isTP4Format bool
}
// NewLegacyLayerWriter returns a LayerWriter that can write the TP4 transport format
// to disk.
func NewLegacyLayerWriter(root string) *LegacyLayerWriter {
return &LegacyLayerWriter{
root: root,
isTP4Format: IsTP4(),
}
}
func (w *LegacyLayerWriter) reset() {
if w.backupWriter != nil {
w.backupWriter.Close()
w.backupWriter = nil
}
if w.currentFile != nil {
w.currentFile.Close()
w.currentFile = nil
}
}
func (w *LegacyLayerWriter) Add(name string, fileInfo *winio.FileBasicInfo) error {
w.reset()
path := filepath.Join(w.root, name)
createDisposition := uint32(syscall.CREATE_NEW)
if (fileInfo.FileAttributes & syscall.FILE_ATTRIBUTE_DIRECTORY) != 0 {
err := os.Mkdir(path, 0)
if err != nil {
return err
}
path += ".$wcidirs$"
}
f, err := openFileOrDir(path, syscall.GENERIC_READ|syscall.GENERIC_WRITE, createDisposition)
if err != nil {
return err
}
defer func() {
if f != nil {
f.Close()
os.Remove(path)
}
}()
strippedFi := *fileInfo
strippedFi.FileAttributes = 0
err = winio.SetFileBasicInfo(f, &strippedFi)
if err != nil {
return err
}
if strings.HasPrefix(name, `Hives\`) {
w.backupWriter = winio.NewBackupFileWriter(f, false)
} else {
if !w.isTP4Format {
// In TP5, the file attributes were added to the header
err = binary.Write(f, binary.LittleEndian, uint32(fileInfo.FileAttributes))
if err != nil {
return err
}
}
}
w.currentFile = f
f = nil
return nil
}
func (w *LegacyLayerWriter) Remove(name string) error {
w.tombstones = append(w.tombstones, name)
return nil
}
func (w *LegacyLayerWriter) Write(b []byte) (int, error) {
if w.backupWriter == nil {
if w.currentFile == nil {
return 0, errors.New("closed")
}
return w.currentFile.Write(b)
}
return w.backupWriter.Write(b)
}
func (w *LegacyLayerWriter) Close() error {
w.reset()
tf, err := os.Create(filepath.Join(w.root, "tombstones.txt"))
if err != nil {
return err
}
defer tf.Close()
_, err = tf.Write([]byte("\xef\xbb\xbfVersion 1.0\n"))
if err != nil {
return err
}
for _, t := range w.tombstones {
_, err = tf.Write([]byte(filepath.Join(`\`, t) + "\n"))
if err != nil {
return err
}
}
return nil
}