package archive import ( "bufio" "fmt" "io" "io/ioutil" "os" "path/filepath" "strings" "syscall" "github.com/docker/docker/vendor/src/code.google.com/p/go/src/pkg/archive/tar" ) // Linux device nodes are a bit weird due to backwards compat with 16 bit device nodes. // They are, from low to high: the lower 8 bits of the minor, then 12 bits of the major, // then the top 12 bits of the minor func mkdev(major int64, minor int64) uint32 { return uint32(((minor & 0xfff00) << 12) | ((major & 0xfff) << 8) | (minor & 0xff)) } // ApplyLayer parses a diff in the standard layer format from `layer`, and // applies it to the directory `dest`. func ApplyLayer(dest string, layer ArchiveReader) error { // We need to be able to set any perms oldmask := syscall.Umask(0) defer syscall.Umask(oldmask) layer, err := DecompressStream(layer) if err != nil { return err } tr := tar.NewReader(layer) trBuf := bufio.NewReaderSize(nil, trBufSize) var dirs []*tar.Header aufsTempdir := "" aufsHardlinks := make(map[string]*tar.Header) // Iterate through the files in the archive. for { hdr, err := tr.Next() if err == io.EOF { // end of tar archive break } if err != nil { return err } // Normalize name, for safety and for a simple is-root check hdr.Name = filepath.Clean(hdr.Name) if !strings.HasSuffix(hdr.Name, "/") { // Not the root directory, ensure that the parent directory exists. // This happened in some tests where an image had a tarfile without any // parent directories. parent := filepath.Dir(hdr.Name) parentPath := filepath.Join(dest, parent) if _, err := os.Lstat(parentPath); err != nil && os.IsNotExist(err) { err = os.MkdirAll(parentPath, 0600) if err != nil { return err } } } // Skip AUFS metadata dirs if strings.HasPrefix(hdr.Name, ".wh..wh.") { // Regular files inside /.wh..wh.plnk can be used as hardlink targets // We don't want this directory, but we need the files in them so that // such hardlinks can be resolved. if strings.HasPrefix(hdr.Name, ".wh..wh.plnk") && hdr.Typeflag == tar.TypeReg { basename := filepath.Base(hdr.Name) aufsHardlinks[basename] = hdr if aufsTempdir == "" { if aufsTempdir, err = ioutil.TempDir("", "dockerplnk"); err != nil { return err } defer os.RemoveAll(aufsTempdir) } if err := createTarFile(filepath.Join(aufsTempdir, basename), dest, hdr, tr, true); err != nil { return err } } continue } path := filepath.Join(dest, hdr.Name) base := filepath.Base(path) if strings.HasPrefix(base, ".wh.") { originalBase := base[len(".wh."):] originalPath := filepath.Join(filepath.Dir(path), originalBase) if err := os.RemoveAll(originalPath); err != nil { return err } } else { // If path exits we almost always just want to remove and replace it. // The only exception is when it is a directory *and* the file from // the layer is also a directory. Then we want to merge them (i.e. // just apply the metadata from the layer). if fi, err := os.Lstat(path); err == nil { if !(fi.IsDir() && hdr.Typeflag == tar.TypeDir) { if err := os.RemoveAll(path); err != nil { return err } } } trBuf.Reset(tr) srcData := io.Reader(trBuf) srcHdr := hdr // Hard links into /.wh..wh.plnk don't work, as we don't extract that directory, so // we manually retarget these into the temporary files we extracted them into if hdr.Typeflag == tar.TypeLink && strings.HasPrefix(filepath.Clean(hdr.Linkname), ".wh..wh.plnk") { linkBasename := filepath.Base(hdr.Linkname) srcHdr = aufsHardlinks[linkBasename] if srcHdr == nil { return fmt.Errorf("Invalid aufs hardlink") } tmpFile, err := os.Open(filepath.Join(aufsTempdir, linkBasename)) if err != nil { return err } defer tmpFile.Close() srcData = tmpFile } if err := createTarFile(path, dest, srcHdr, srcData, true); err != nil { return err } // Directory mtimes must be handled at the end to avoid further // file creation in them to modify the directory mtime if hdr.Typeflag == tar.TypeDir { dirs = append(dirs, hdr) } } } for _, hdr := range dirs { path := filepath.Join(dest, hdr.Name) ts := []syscall.Timespec{timeToTimespec(hdr.AccessTime), timeToTimespec(hdr.ModTime)} if err := syscall.UtimesNano(path, ts); err != nil { return err } } return nil }