package archive import ( "bytes" "compress/bzip2" "compress/gzip" "errors" "fmt" "github.com/dotcloud/docker/utils" "github.com/dotcloud/docker/vendor/src/code.google.com/p/go/src/pkg/archive/tar" "io" "io/ioutil" "os" "os/exec" "path" "path/filepath" "strings" "syscall" ) type ( Archive io.ReadCloser ArchiveReader io.Reader Compression int TarOptions struct { Includes []string Compression Compression } ) var ( ErrNotImplemented = errors.New("Function not implemented") ) const ( Uncompressed Compression = iota Bzip2 Gzip Xz ) func DetectCompression(source []byte) Compression { sourceLen := len(source) for compression, m := range map[Compression][]byte{ Bzip2: {0x42, 0x5A, 0x68}, Gzip: {0x1F, 0x8B, 0x08}, Xz: {0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00}, } { fail := false if len(m) > sourceLen { utils.Debugf("Len too short") continue } i := 0 for _, b := range m { if b != source[i] { fail = true break } i++ } if !fail { return compression } } return Uncompressed } func xzDecompress(archive io.Reader) (io.ReadCloser, error) { args := []string{"xz", "-d", "-c", "-q"} return CmdStream(exec.Command(args[0], args[1:]...), archive) } func DecompressStream(archive io.Reader) (io.ReadCloser, error) { buf := make([]byte, 10) totalN := 0 for totalN < 10 { n, err := archive.Read(buf[totalN:]) if err != nil { if err == io.EOF { return nil, fmt.Errorf("Tarball too short") } return nil, err } totalN += n utils.Debugf("[tar autodetect] n: %d", n) } compression := DetectCompression(buf) wrap := io.MultiReader(bytes.NewReader(buf), archive) switch compression { case Uncompressed: return ioutil.NopCloser(wrap), nil case Gzip: return gzip.NewReader(wrap) case Bzip2: return ioutil.NopCloser(bzip2.NewReader(wrap)), nil case Xz: return xzDecompress(wrap) default: return nil, fmt.Errorf("Unsupported compression format %s", (&compression).Extension()) } } func CompressStream(dest io.WriteCloser, compression Compression) (io.WriteCloser, error) { switch compression { case Uncompressed: return utils.NopWriteCloser(dest), nil case Gzip: return gzip.NewWriter(dest), nil case Bzip2, Xz: // archive/bzip2 does not support writing, and there is no xz support at all // However, this is not a problem as docker only currently generates gzipped tars return nil, fmt.Errorf("Unsupported compression format %s", (&compression).Extension()) default: return nil, fmt.Errorf("Unsupported compression format %s", (&compression).Extension()) } } func (compression *Compression) Extension() string { switch *compression { case Uncompressed: return "tar" case Bzip2: return "tar.bz2" case Gzip: return "tar.gz" case Xz: return "tar.xz" } return "" } func addTarFile(path, name string, tw *tar.Writer) error { fi, err := os.Lstat(path) if err != nil { return err } link := "" if fi.Mode()&os.ModeSymlink != 0 { if link, err = os.Readlink(path); err != nil { return err } } hdr, err := tar.FileInfoHeader(fi, link) if err != nil { return err } if fi.IsDir() && !strings.HasSuffix(name, "/") { name = name + "/" } hdr.Name = name stat, ok := fi.Sys().(*syscall.Stat_t) if ok { // Currently go does not fill in the major/minors if stat.Mode&syscall.S_IFBLK == syscall.S_IFBLK || stat.Mode&syscall.S_IFCHR == syscall.S_IFCHR { hdr.Devmajor = int64(major(uint64(stat.Rdev))) hdr.Devminor = int64(minor(uint64(stat.Rdev))) } } capability, _ := Lgetxattr(path, "security.capability") if capability != nil { hdr.Xattrs = make(map[string]string) hdr.Xattrs["security.capability"] = string(capability) } if err := tw.WriteHeader(hdr); err != nil { return err } if hdr.Typeflag == tar.TypeReg { if file, err := os.Open(path); err != nil { return err } else { _, err := io.Copy(tw, file) if err != nil { return err } file.Close() } } return nil } func createTarFile(path, extractDir string, hdr *tar.Header, reader io.Reader) error { // hdr.Mode is in linux format, which we can use for sycalls, // but for os.Foo() calls we need the mode converted to os.FileMode, // so use hdrInfo.Mode() (they differ for e.g. setuid bits) hdrInfo := hdr.FileInfo() switch hdr.Typeflag { case tar.TypeDir: // Create directory unless it exists as a directory already. // In that case we just want to merge the two if fi, err := os.Lstat(path); !(err == nil && fi.IsDir()) { if err := os.Mkdir(path, hdrInfo.Mode()); err != nil { return err } } case tar.TypeReg, tar.TypeRegA: // Source is regular file file, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, hdrInfo.Mode()) if err != nil { return err } if _, err := io.Copy(file, reader); err != nil { file.Close() return err } file.Close() case tar.TypeBlock, tar.TypeChar, tar.TypeFifo: mode := uint32(hdr.Mode & 07777) switch hdr.Typeflag { case tar.TypeBlock: mode |= syscall.S_IFBLK case tar.TypeChar: mode |= syscall.S_IFCHR case tar.TypeFifo: mode |= syscall.S_IFIFO } if err := syscall.Mknod(path, mode, int(mkdev(hdr.Devmajor, hdr.Devminor))); err != nil { return err } case tar.TypeLink: if err := os.Link(filepath.Join(extractDir, hdr.Linkname), path); err != nil { return err } case tar.TypeSymlink: if err := os.Symlink(hdr.Linkname, path); err != nil { return err } case tar.TypeXGlobalHeader: utils.Debugf("PAX Global Extended Headers found and ignored") return nil default: return fmt.Errorf("Unhandled tar header type %d\n", hdr.Typeflag) } if err := os.Lchown(path, hdr.Uid, hdr.Gid); err != nil { return err } for key, value := range hdr.Xattrs { if err := Lsetxattr(path, key, []byte(value), 0); err != nil { return err } } // There is no LChmod, so ignore mode for symlink. Also, this // must happen after chown, as that can modify the file mode if hdr.Typeflag != tar.TypeSymlink { if err := os.Chmod(path, hdrInfo.Mode()); err != nil { return err } } ts := []syscall.Timespec{timeToTimespec(hdr.AccessTime), timeToTimespec(hdr.ModTime)} // syscall.UtimesNano doesn't support a NOFOLLOW flag atm, and if hdr.Typeflag != tar.TypeSymlink { if err := UtimesNano(path, ts); err != nil { return err } } else { if err := LUtimesNano(path, ts); err != nil { return err } } return nil } // Tar creates an archive from the directory at `path`, and returns it as a // stream of bytes. func Tar(path string, compression Compression) (io.ReadCloser, error) { return TarFilter(path, &TarOptions{Compression: compression}) } func escapeName(name string) string { escaped := make([]byte, 0) for i, c := range []byte(name) { if i == 0 && c == '/' { continue } // all printable chars except "-" which is 0x2d if (0x20 <= c && c <= 0x7E) && c != 0x2d { escaped = append(escaped, c) } else { escaped = append(escaped, fmt.Sprintf("\\%03o", c)...) } } return string(escaped) } // Tar creates an archive from the directory at `path`, only including files whose relative // paths are included in `filter`. If `filter` is nil, then all files are included. func TarFilter(srcPath string, options *TarOptions) (io.ReadCloser, error) { pipeReader, pipeWriter := io.Pipe() compressWriter, err := CompressStream(pipeWriter, options.Compression) if err != nil { return nil, err } tw := tar.NewWriter(compressWriter) go func() { // In general we log errors here but ignore them because // during e.g. a diff operation the container can continue // mutating the filesystem and we can see transient errors // from this if options.Includes == nil { options.Includes = []string{"."} } for _, include := range options.Includes { filepath.Walk(filepath.Join(srcPath, include), func(filePath string, f os.FileInfo, err error) error { if err != nil { utils.Debugf("Tar: Can't stat file %s to tar: %s\n", srcPath, err) return nil } relFilePath, err := filepath.Rel(srcPath, filePath) if err != nil { return nil } if err := addTarFile(filePath, relFilePath, tw); err != nil { utils.Debugf("Can't add file %s to tar: %s\n", srcPath, err) } return nil }) } // Make sure to check the error on Close. if err := tw.Close(); err != nil { utils.Debugf("Can't close tar writer: %s\n", err) } if err := compressWriter.Close(); err != nil { utils.Debugf("Can't close compress writer: %s\n", err) } if err := pipeWriter.Close(); err != nil { utils.Debugf("Can't close pipe writer: %s\n", err) } }() return pipeReader, nil } // Untar reads a stream of bytes from `archive`, parses it as a tar archive, // and unpacks it into the directory at `path`. // The archive may be compressed with one of the following algorithms: // identity (uncompressed), gzip, bzip2, xz. // FIXME: specify behavior when target path exists vs. doesn't exist. func Untar(archive io.Reader, dest string, options *TarOptions) error { if archive == nil { return fmt.Errorf("Empty archive") } decompressedArchive, err := DecompressStream(archive) if err != nil { return err } defer decompressedArchive.Close() tr := tar.NewReader(decompressedArchive) var dirs []*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 parent := filepath.Dir(hdr.Name) parentPath := filepath.Join(dest, parent) if _, err := os.Lstat(parentPath); err != nil && os.IsNotExist(err) { err = os.MkdirAll(parentPath, 600) if err != nil { return err } } } path := filepath.Join(dest, hdr.Name) // 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 } } } if err := createTarFile(path, dest, hdr, tr); 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 } // TarUntar is a convenience function which calls Tar and Untar, with // the output of one piped into the other. If either Tar or Untar fails, // TarUntar aborts and returns the error. func TarUntar(src string, dst string) error { utils.Debugf("TarUntar(%s %s)", src, dst) archive, err := TarFilter(src, &TarOptions{Compression: Uncompressed}) if err != nil { return err } defer archive.Close() return Untar(archive, dst, nil) } // UntarPath is a convenience function which looks for an archive // at filesystem path `src`, and unpacks it at `dst`. func UntarPath(src, dst string) error { archive, err := os.Open(src) if err != nil { return err } defer archive.Close() if err := Untar(archive, dst, nil); err != nil { return err } return nil } // CopyWithTar creates a tar archive of filesystem path `src`, and // unpacks it at filesystem path `dst`. // The archive is streamed directly with fixed buffering and no // intermediary disk IO. // func CopyWithTar(src, dst string) error { srcSt, err := os.Stat(src) if err != nil { return err } if !srcSt.IsDir() { return CopyFileWithTar(src, dst) } // Create dst, copy src's content into it utils.Debugf("Creating dest directory: %s", dst) if err := os.MkdirAll(dst, 0755); err != nil && !os.IsExist(err) { return err } utils.Debugf("Calling TarUntar(%s, %s)", src, dst) return TarUntar(src, dst) } // CopyFileWithTar emulates the behavior of the 'cp' command-line // for a single file. It copies a regular file from path `src` to // path `dst`, and preserves all its metadata. // // If `dst` ends with a trailing slash '/', the final destination path // will be `dst/base(src)`. func CopyFileWithTar(src, dst string) (err error) { utils.Debugf("CopyFileWithTar(%s, %s)", src, dst) srcSt, err := os.Stat(src) if err != nil { return err } if srcSt.IsDir() { return fmt.Errorf("Can't copy a directory") } // Clean up the trailing / if dst[len(dst)-1] == '/' { dst = path.Join(dst, filepath.Base(src)) } // Create the holding directory if necessary if err := os.MkdirAll(filepath.Dir(dst), 0700); err != nil && !os.IsExist(err) { return err } r, w := io.Pipe() errC := utils.Go(func() error { defer w.Close() srcF, err := os.Open(src) if err != nil { return err } defer srcF.Close() tw := tar.NewWriter(w) hdr, err := tar.FileInfoHeader(srcSt, "") if err != nil { return err } hdr.Name = filepath.Base(dst) if err := tw.WriteHeader(hdr); err != nil { return err } if _, err := io.Copy(tw, srcF); err != nil { return err } tw.Close() return nil }) defer func() { if er := <-errC; err != nil { err = er } }() return Untar(r, filepath.Dir(dst), nil) } // CmdStream executes a command, and returns its stdout as a stream. // If the command fails to run or doesn't complete successfully, an error // will be returned, including anything written on stderr. func CmdStream(cmd *exec.Cmd, input io.Reader) (io.ReadCloser, error) { if input != nil { stdin, err := cmd.StdinPipe() if err != nil { return nil, err } // Write stdin if any go func() { io.Copy(stdin, input) stdin.Close() }() } stdout, err := cmd.StdoutPipe() if err != nil { return nil, err } stderr, err := cmd.StderrPipe() if err != nil { return nil, err } pipeR, pipeW := io.Pipe() errChan := make(chan []byte) // Collect stderr, we will use it in case of an error go func() { errText, e := ioutil.ReadAll(stderr) if e != nil { errText = []byte("(...couldn't fetch stderr: " + e.Error() + ")") } errChan <- errText }() // Copy stdout to the returned pipe go func() { _, err := io.Copy(pipeW, stdout) if err != nil { pipeW.CloseWithError(err) } errText := <-errChan if err := cmd.Wait(); err != nil { pipeW.CloseWithError(fmt.Errorf("%s: %s", err, errText)) } else { pipeW.Close() } }() // Run the command and return the pipe if err := cmd.Start(); err != nil { return nil, err } return pipeR, nil } // NewTempArchive reads the content of src into a temporary file, and returns the contents // of that file as an archive. The archive can only be read once - as soon as reading completes, // the file will be deleted. func NewTempArchive(src Archive, dir string) (*TempArchive, error) { f, err := ioutil.TempFile(dir, "") if err != nil { return nil, err } if _, err := io.Copy(f, src); err != nil { return nil, err } if _, err := f.Seek(0, 0); err != nil { return nil, err } st, err := f.Stat() if err != nil { return nil, err } size := st.Size() return &TempArchive{f, size}, nil } type TempArchive struct { *os.File Size int64 // Pre-computed from Stat().Size() as a convenience } func (archive *TempArchive) Read(data []byte) (int, error) { n, err := archive.File.Read(data) if err != nil { os.Remove(archive.File.Name()) } return n, err }