package docker import ( "archive/tar" "bytes" "fmt" "github.com/dotcloud/docker/utils" "io" "io/ioutil" "os" "os/exec" "path" "path/filepath" ) type Archive io.Reader type Compression uint32 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 (compression *Compression) Flag() string { switch *compression { case Bzip2: return "j" case Gzip: return "z" case Xz: return "J" } return "" } 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 "" } // Tar creates an archive from the directory at `path`, and returns it as a // stream of bytes. func Tar(path string, compression Compression) (io.Reader, error) { return TarFilter(path, compression, nil) } // 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(path string, compression Compression, filter []string) (io.Reader, error) { args := []string{"tar", "--numeric-owner", "-f", "-", "-C", path} if filter == nil { filter = []string{"."} } for _, f := range filter { args = append(args, "-c"+compression.Flag(), f) } return CmdStream(exec.Command(args[0], args[1:]...)) } // 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 algorithgms: // identity (uncompressed), gzip, bzip2, xz. // FIXME: specify behavior when target path exists vs. doesn't exist. func Untar(archive io.Reader, path string) error { if archive == nil { return fmt.Errorf("Empty archive") } buf := make([]byte, 10) totalN := 0 for totalN < 10 { if n, err := archive.Read(buf[totalN:]); err != nil { if err == io.EOF { return fmt.Errorf("Tarball too short") } return err } else { totalN += n utils.Debugf("[tar autodetect] n: %d", n) } } compression := DetectCompression(buf) utils.Debugf("Archive compression detected: %s", compression.Extension()) cmd := exec.Command("tar", "--numeric-owner", "-f", "-", "-C", path, "-x"+compression.Flag()) cmd.Stdin = io.MultiReader(bytes.NewReader(buf), archive) // Hardcode locale environment for predictable outcome regardless of host configuration. // (see https://github.com/dotcloud/docker/issues/355) cmd.Env = []string{"LANG=en_US.utf-8", "LC_ALL=en_US.utf-8"} output, err := cmd.CombinedOutput() if err != nil { return fmt.Errorf("%s: %s", err, output) } 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, filter []string, dst string) error { utils.Debugf("TarUntar(%s %s %s)", src, filter, dst) archive, err := TarFilter(src, Uncompressed, filter) if err != nil { return err } return Untar(archive, dst) } // 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 { if archive, err := os.Open(src); err != nil { return err } else if err := Untar(archive, dst); 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, nil, 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) 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 } buf := new(bytes.Buffer) tw := tar.NewWriter(buf) hdr, err := tar.FileInfoHeader(srcSt, "") if err != nil { return err } hdr.Name = filepath.Base(dst) if err := tw.WriteHeader(hdr); err != nil { return err } srcF, err := os.Open(src) if err != nil { return err } if _, err := io.Copy(tw, srcF); err != nil { return err } tw.Close() return Untar(buf, filepath.Dir(dst)) } // 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) (io.Reader, error) { 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 }