buildkit/vendor/github.com/Microsoft/hcsshim/legacy.go

749 lines
17 KiB
Go

package hcsshim
import (
"bufio"
"encoding/binary"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"syscall"
"github.com/Microsoft/go-winio"
)
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 makeLongAbsPath(path string) (string, error) {
if strings.HasPrefix(path, `\\?\`) || strings.HasPrefix(path, `\\.\`) {
return path, nil
}
if !filepath.IsAbs(path) {
absPath, err := filepath.Abs(path)
if err != nil {
return "", err
}
path = absPath
}
if strings.HasPrefix(path, `\\`) {
return `\\?\UNC\` + path[2:], nil
}
return `\\?\` + path, nil
}
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 := makeLongAbsPath(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
}
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 = uintptr(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
}
type legacyLayerWriter struct {
root string
parentRoots []string
destRoot string
currentFile *os.File
backupWriter *winio.BackupFileWriter
tombstones []string
pathFixed bool
HasUtilityVM bool
uvmDi []dirInfo
addedFiles map[string]bool
PendingLinks []pendingLink
}
// newLegacyLayerWriter returns a LayerWriter that can write the contaler layer
// transport format to disk.
func newLegacyLayerWriter(root string, parentRoots []string, destRoot string) *legacyLayerWriter {
return &legacyLayerWriter{
root: root,
parentRoots: parentRoots,
destRoot: destRoot,
addedFiles: make(map[string]bool),
}
}
func (w *legacyLayerWriter) init() error {
if !w.pathFixed {
path, err := makeLongAbsPath(w.root)
if err != nil {
return err
}
for i, p := range w.parentRoots {
w.parentRoots[i], err = makeLongAbsPath(p)
if err != nil {
return err
}
}
destPath, err := makeLongAbsPath(w.destRoot)
if err != nil {
return err
}
w.root = path
w.destRoot = destPath
w.pathFixed = true
}
return nil
}
func (w *legacyLayerWriter) initUtilityVM() error {
if !w.HasUtilityVM {
err := os.Mkdir(filepath.Join(w.destRoot, utilityVMPath), 0)
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(filepath.Join(w.parentRoots[0], utilityVMFilesPath), filepath.Join(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() {
if w.backupWriter != nil {
w.backupWriter.Close()
w.backupWriter = nil
}
if w.currentFile != nil {
w.currentFile.Close()
w.currentFile = nil
}
}
// copyFileWithMetadata copies a file using the backup/restore APIs in order to preserve metadata
func copyFileWithMetadata(srcPath, destPath string, isDir bool) (fileInfo *winio.FileBasicInfo, err error) {
createDisposition := uint32(syscall.CREATE_NEW)
if isDir {
err = os.Mkdir(destPath, 0)
if err != nil {
return nil, err
}
createDisposition = syscall.OPEN_EXISTING
}
src, err := openFileOrDir(srcPath, syscall.GENERIC_READ|winio.ACCESS_SYSTEM_SECURITY, syscall.OPEN_EXISTING)
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
}
dest, err := openFileOrDir(destPath, syscall.GENERIC_READ|syscall.GENERIC_WRITE|winio.WRITE_DAC|winio.WRITE_OWNER|winio.ACCESS_SYSTEM_SECURITY, createDisposition)
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(srcPath, destPath string, mutatedFiles map[string]bool) error {
var di []dirInfo
err := filepath.Walk(srcPath, func(srcFilePath string, info os.FileInfo, err error) error {
if err != nil {
return err
}
relPath, err := filepath.Rel(srcPath, srcFilePath)
if err != nil {
return err
}
destFilePath := filepath.Join(destPath, relPath)
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(srcFilePath, destFilePath, isDir)
if err != nil {
return err
}
if isDir && !isReparsePoint {
di = append(di, dirInfo{path: destFilePath, fileInfo: *fi})
}
} else {
err = os.Link(srcFilePath, destFilePath)
if err != nil {
return err
}
}
// Don't recurse on reparse points in go1.8 and older. Filepath.Walk
// handles this in go1.9 and newer.
if isDir && isReparsePoint && shouldSkipDirectoryReparse {
return filepath.SkipDir
}
return nil
})
if err != nil {
return err
}
return reapplyDirectoryTimes(di)
}
func (w *legacyLayerWriter) Add(name string, fileInfo *winio.FileBasicInfo) error {
w.reset()
err := w.init()
if err != nil {
return err
}
if name == utilityVMPath {
return w.initUtilityVM()
}
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")
}
path := filepath.Join(w.destRoot, name)
createDisposition := uint32(syscall.OPEN_EXISTING)
if (fileInfo.FileAttributes & syscall.FILE_ATTRIBUTE_DIRECTORY) != 0 {
st, err := os.Lstat(path)
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 = os.RemoveAll(path); err != nil {
return err
}
st = nil
}
}
if st == nil {
if err = os.Mkdir(path, 0); err != nil {
return err
}
}
if fileInfo.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT == 0 {
w.uvmDi = append(w.uvmDi, dirInfo{path: path, fileInfo: *fileInfo})
}
} else {
// Overwrite any existing hard link.
err = os.Remove(path)
if err != nil && !os.IsNotExist(err) {
return err
}
createDisposition = syscall.CREATE_NEW
}
f, err := openFileOrDir(path, syscall.GENERIC_READ|syscall.GENERIC_WRITE|winio.WRITE_DAC|winio.WRITE_OWNER|winio.ACCESS_SYSTEM_SECURITY, createDisposition)
if err != nil {
return err
}
defer func() {
if f != nil {
f.Close()
os.Remove(path)
}
}()
err = winio.SetFileBasicInfo(f, fileInfo)
if err != nil {
return err
}
w.backupWriter = winio.NewBackupFileWriter(f, true)
w.currentFile = f
w.addedFiles[name] = true
f = nil
return nil
}
path := filepath.Join(w.root, name)
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, syscall.CREATE_NEW)
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 hasPathPrefix(name, hivesPath) {
w.backupWriter = winio.NewBackupFileWriter(f, false)
} else {
// The file attributes are written before the stream.
err = binary.Write(f, binary.LittleEndian, uint32(fileInfo.FileAttributes))
if err != nil {
return err
}
}
w.currentFile = f
w.addedFiles[name] = true
f = nil
return nil
}
func (w *legacyLayerWriter) AddLink(name string, target string) error {
w.reset()
err := w.init()
if err != nil {
return err
}
var roots []string
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 = []string{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 string
if _, ok := w.addedFiles[target]; ok {
selectedRoot = w.destRoot
} else {
for _, r := range roots {
if _, err = os.Lstat(filepath.Join(r, target)); err != nil {
if !os.IsNotExist(err) {
return err
}
} else {
selectedRoot = r
break
}
}
if selectedRoot == "" {
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: filepath.Join(w.destRoot, name),
Target: filepath.Join(selectedRoot, target),
})
w.addedFiles[name] = true
return nil
}
func (w *legacyLayerWriter) Remove(name string) error {
if hasPathPrefix(name, filesPath) {
w.tombstones = append(w.tombstones, name[len(filesPath)+1:])
} 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.
path := filepath.Join(w.destRoot, name)
if _, err := os.Lstat(path); err != nil {
return err
}
err = os.RemoveAll(path)
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 {
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()
err := w.init()
if err != nil {
return err
}
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
}
}
if w.HasUtilityVM {
err = reapplyDirectoryTimes(w.uvmDi)
if err != nil {
return err
}
}
return nil
}