package archive
import (
"bufio"
"bytes"
"compress/bzip2"
"compress/gzip"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"path"
"path/filepath"
"strings"
"syscall"
"github.com/dotcloud/docker/pkg/system"
"github.com/dotcloud/docker/utils"
"github.com/dotcloud/docker/vendor/src/code.google.com/p/go/src/pkg/archive/tar"
)
type (
Archive io.ReadCloser
ArchiveReader io.Reader
Compression int
TarOptions struct {
Includes []string
Compression Compression
NoLchown bool
}
)
var (
ErrNotImplemented = errors.New("Function not implemented")
)
const (
Uncompressed Compression = iota
Bzip2
Gzip
Xz
)
func DetectCompression(source []byte) Compression {
for compression, m := range map[Compression][]byte{
Bzip2: {0x42, 0x5A, 0x68},
Gzip: {0x1F, 0x8B, 0x08},
Xz: {0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00},
} {
if len(source) < len(m) {
utils.Debugf("Len too short")
continue
}
if bytes.Compare(m, source[:len(m)]) == 0 {
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 := bufio.NewReader(archive)
bs, err := buf.Peek(10)
if err != nil {
return nil, err
}
utils.Debugf("[tar autodetect] n: %v", bs)
compression := DetectCompression(bs)
switch compression {
case Uncompressed:
return ioutil.NopCloser(buf), nil
case Gzip:
return gzip.NewReader(buf)
case Bzip2:
return ioutil.NopCloser(bzip2.NewReader(buf)), nil
case Xz:
return xzDecompress(buf)
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, _ := system.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, Lchown bool) 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 && Lchown {
return err
}
for key, value := range hdr.Xattrs {
if err := system.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 := system.UtimesNano(path, ts); err != nil && err != system.ErrNotSupportedPlatform {
return err
}
} else {
if err := system.LUtimesNano(path, ts); err != nil && err != system.ErrNotSupportedPlatform {
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)
}
// TarFilter creates an archive from the directory at `srcPath` with `options`, and returns it as a
// stream of bytes.
//
// Files are included according to `options.Includes`, default to including all files.
// Stream is compressed according to `options.Compression', default to Uncompressed.
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, 0777)
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.Name == "." {
continue
}
if !(fi.IsDir() && hdr.Typeflag == tar.TypeDir) {
if err := os.RemoveAll(path); err != nil {
return err
}
}
}
if err := createTarFile(path, dest, hdr, tr, options == nil || !options.NoLchown); 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.Sync(); 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
}