Golang tar.NewWriter函数代码示例

func TestPushEmptyLayer(t *testing.T) {
	defer setupRegistry(t)()
	repoName := fmt.Sprintf("%v/dockercli/emptylayer", privateRegistryURL)
	emptyTarball, err := ioutil.TempFile("", "empty_tarball")
	if err != nil {
		t.Fatalf("Unable to create test file: %v", err)
	}
	tw := tar.NewWriter(emptyTarball)
	err = tw.Close()
	if err != nil {
		t.Fatalf("Error creating empty tarball: %v", err)
	}
	freader, err := os.Open(emptyTarball.Name())
	if err != nil {
		t.Fatalf("Could not open test tarball: %v", err)
	}

	importCmd := exec.Command(dockerBinary, "import", "-", repoName)
	importCmd.Stdin = freader
	out, _, err := runCommandWithOutput(importCmd)
	if err != nil {
		t.Errorf("import failed with errors: %v, output: %q", err, out)
	}

	// Now verify we can push it
	pushCmd := exec.Command(dockerBinary, "push", repoName)
	if out, _, err := runCommandWithOutput(pushCmd); err != nil {
		t.Fatalf("pushing the image to the private registry has failed: %s, %v", out, err)
	}
	logDone("push - empty layer config to private registry")
}

func TestBuildApiDockerfileSymlink(t *testing.T) {
	// Test to make sure we stop people from trying to leave the
	// build context when specifying a symlink as the path to the dockerfile
	buffer := new(bytes.Buffer)
	tw := tar.NewWriter(buffer)
	defer tw.Close()

	if err := tw.WriteHeader(&tar.Header{
		Name:     "Dockerfile",
		Typeflag: tar.TypeSymlink,
		Linkname: "/etc/passwd",
	}); err != nil {
		t.Fatalf("failed to write tar file header: %v", err)
	}
	if err := tw.Close(); err != nil {
		t.Fatalf("failed to close tar archive: %v", err)
	}

	out, err := sockRequestRaw("POST", "/build", buffer, "application/x-tar")
	if err == nil {
		t.Fatalf("Build was supposed to fail: %s", out)
	}

	// The reason the error is "Cannot locate specified Dockerfile" is because
	// in the builder, the symlink is resolved within the context, therefore
	// Dockerfile -> /etc/passwd becomes etc/passwd from the context which is
	// a nonexistent file.
	if !strings.Contains(string(out), "Cannot locate specified Dockerfile: Dockerfile") {
		t.Fatalf("Didn't complain about leaving build context: %s", out)
	}

	logDone("container REST API - check build w/bad Dockerfile symlink path")
}

func renderSumForHeader(v Version, h *tar.Header, data []byte) (string, error) {
	buf := bytes.NewBuffer(nil)
	// first build our test tar
	tw := tar.NewWriter(buf)
	if err := tw.WriteHeader(h); err != nil {
		return "", err
	}
	if _, err := tw.Write(data); err != nil {
		return "", err
	}
	tw.Close()

	ts, err := NewTarSum(buf, true, v)
	if err != nil {
		return "", err
	}
	tr := tar.NewReader(ts)
	for {
		hdr, err := tr.Next()
		if hdr == nil || err == io.EOF {
			// Signals the end of the archive.
			break
		}
		if err != nil {
			return "", err
		}
		if _, err = io.Copy(ioutil.Discard, tr); err != nil {
			return "", err
		}
	}
	return ts.Sum(nil), nil
}

// GetTar generates a tar stream frmo the contents of db, and streams
// it to `dst`.
func (db *DB) GetTar(dst io.Writer) error {
	tw := tar.NewWriter(dst)
	defer tw.Close()
	// Walk the data tree
	return db.Walk(DataTree, func(name string, obj git.Object) error {
		fmt.Fprintf(os.Stderr, "Generating tar entry for '%s'...\n", name)
		metaBlob, err := db.Get(metaPath(name))
		if err != nil {
			return err
		}
		tr := tar.NewReader(bytes.NewReader([]byte(metaBlob)))
		hdr, err := tr.Next()
		if err != nil {
			return err
		}
		// Write the reconstituted tar header+content
		if err := tw.WriteHeader(hdr); err != nil {
			return err
		}
		if blob, isBlob := obj.(*git.Blob); isBlob {
			fmt.Fprintf(os.Stderr, "--> writing %d bytes for blob %s\n", hdr.Size, hdr.Name)
			if _, err := tw.Write(blob.Contents()[:hdr.Size]); err != nil {
				return err
			}
		}
		return nil
	})
	return nil
}

func TestBuildApiDockerfilePath(t *testing.T) {
	// Test to make sure we stop people from trying to leave the
	// build context when specifying the path to the dockerfile
	buffer := new(bytes.Buffer)
	tw := tar.NewWriter(buffer)
	defer tw.Close()

	dockerfile := []byte("FROM busybox")
	if err := tw.WriteHeader(&tar.Header{
		Name: "Dockerfile",
		Size: int64(len(dockerfile)),
	}); err != nil {
		t.Fatalf("failed to write tar file header: %v", err)
	}
	if _, err := tw.Write(dockerfile); err != nil {
		t.Fatalf("failed to write tar file content: %v", err)
	}
	if err := tw.Close(); err != nil {
		t.Fatalf("failed to close tar archive: %v", err)
	}

	out, err := sockRequestRaw("POST", "/build?dockerfile=../Dockerfile", buffer, "application/x-tar")
	if err == nil {
		t.Fatalf("Build was supposed to fail: %s", out)
	}

	if !strings.Contains(string(out), "must be within the build context") {
		t.Fatalf("Didn't complain about leaving build context: %s", out)
	}

	logDone("container REST API - check build w/bad Dockerfile path")
}

func headerReader(hdr *tar.Header) (io.Reader, error) {
	var buf bytes.Buffer
	w := tar.NewWriter(&buf)
	defer w.Close()
	if err := w.WriteHeader(hdr); err != nil {
		return nil, err
	}
	return &buf, nil
}

func (archiver *Archiver) CopyFileWithTar(src, dst string) (err error) {
	logrus.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 := promise.Go(func() error {
		defer w.Close()

		srcF, err := os.Open(src)
		if err != nil {
			return err
		}
		defer srcF.Close()

		hdr, err := tar.FileInfoHeader(srcSt, "")
		if err != nil {
			return err
		}
		hdr.Name = filepath.Base(dst)
		hdr.Mode = int64(chmodTarEntry(os.FileMode(hdr.Mode)))

		tw := tar.NewWriter(w)
		defer tw.Close()
		if err := tw.WriteHeader(hdr); err != nil {
			return err
		}
		if _, err := io.Copy(tw, srcF); err != nil {
			return err
		}
		return nil
	})
	defer func() {
		if er := <-errC; err != nil {
			err = er
		}
	}()
	return archiver.Untar(r, filepath.Dir(dst), nil)
}

func emptyTarSum(gzip bool) (TarSum, error) {
	reader, writer := io.Pipe()
	tarWriter := tar.NewWriter(writer)

	// Immediately close tarWriter and write-end of the
	// Pipe in a separate goroutine so we don't block.
	go func() {
		tarWriter.Close()
		writer.Close()
	}()

	return NewTarSum(reader, !gzip, Version0)
}

// ExportChanges produces an Archive from the provided changes, relative to dir.
func ExportChanges(dir string, changes []Change) (Archive, error) {
	reader, writer := io.Pipe()
	go func() {
		ta := &tarAppender{
			TarWriter: tar.NewWriter(writer),
			Buffer:    pools.BufioWriter32KPool.Get(nil),
			SeenFiles: make(map[uint64]string),
		}
		// this buffer is needed for the duration of this piped stream
		defer pools.BufioWriter32KPool.Put(ta.Buffer)

		sort.Sort(changesByPath(changes))

		// 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
		for _, change := range changes {
			if change.Kind == ChangeDelete {
				whiteOutDir := filepath.Dir(change.Path)
				whiteOutBase := filepath.Base(change.Path)
				whiteOut := filepath.Join(whiteOutDir, ".wh."+whiteOutBase)
				timestamp := time.Now()
				hdr := &tar.Header{
					Name:       whiteOut[1:],
					Size:       0,
					ModTime:    timestamp,
					AccessTime: timestamp,
					ChangeTime: timestamp,
				}
				if err := ta.TarWriter.WriteHeader(hdr); err != nil {
					logrus.Debugf("Can't write whiteout header: %s", err)
				}
			} else {
				path := filepath.Join(dir, change.Path)
				if err := ta.addTarFile(path, change.Path[1:]); err != nil {
					logrus.Debugf("Can't add file %s to tar: %s", path, err)
				}
			}
		}

		// Make sure to check the error on Close.
		if err := ta.TarWriter.Close(); err != nil {
			logrus.Debugf("Can't close layer: %s", err)
		}
		if err := writer.Close(); err != nil {
			logrus.Debugf("failed close Changes writer: %s", err)
		}
	}()
	return reader, nil
}

// FIXME: this is duplicated from graph_test.go in the docker package.
func fakeTar() (io.ReadCloser, error) {
	content := []byte("Hello world!\n")
	buf := new(bytes.Buffer)
	tw := tar.NewWriter(buf)
	for _, name := range []string{"/etc/postgres/postgres.conf", "/etc/passwd", "/var/log/postgres/postgres.conf"} {
		hdr := new(tar.Header)
		hdr.Size = int64(len(content))
		hdr.Name = name
		if err := tw.WriteHeader(hdr); err != nil {
			return nil, err
		}
		tw.Write([]byte(content))
	}
	tw.Close()
	return ioutil.NopCloser(buf), nil
}

func ExportChanges(dir string, changes []Change) (Archive, error) {
	reader, writer := io.Pipe()
	tw := tar.NewWriter(writer)

	go func() {
		twBuf := pools.BufioWriter32KPool.Get(nil)
		defer pools.BufioWriter32KPool.Put(twBuf)
		// 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
		for _, change := range changes {
			if change.Kind == ChangeDelete {
				whiteOutDir := filepath.Dir(change.Path)
				whiteOutBase := filepath.Base(change.Path)
				whiteOut := filepath.Join(whiteOutDir, ".wh."+whiteOutBase)
				timestamp := time.Now()
				hdr := &tar.Header{
					Name:       whiteOut[1:],
					Size:       0,
					ModTime:    timestamp,
					AccessTime: timestamp,
					ChangeTime: timestamp,
				}
				if err := tw.WriteHeader(hdr); err != nil {
					log.Debugf("Can't write whiteout header: %s", err)
				}
			} else {
				path := filepath.Join(dir, change.Path)
				if err := addTarFile(path, change.Path[1:], tw, twBuf); err != nil {
					log.Debugf("Can't add file %s to tar: %s", path, err)
				}
			}
		}

		// Make sure to check the error on Close.
		if err := tw.Close(); err != nil {
			log.Debugf("Can't close layer: %s", err)
		}
		writer.Close()
	}()
	return reader, nil
}

func (ts *tarSum) initTarSum() error {
	ts.bufTar = bytes.NewBuffer([]byte{})
	ts.bufWriter = bytes.NewBuffer([]byte{})
	ts.tarR = tar.NewReader(ts.Reader)
	ts.tarW = tar.NewWriter(ts.bufTar)
	if !ts.DisableCompression {
		ts.writer = gzip.NewWriter(ts.bufWriter)
	} else {
		ts.writer = &nopCloseFlusher{Writer: ts.bufWriter}
	}
	if ts.tHash == nil {
		ts.tHash = DefaultTHash
	}
	ts.h = ts.tHash.Hash()
	ts.h.Reset()
	ts.first = true
	ts.sums = FileInfoSums{}
	return nil
}

// make a tar:
// * num is the number of files the tar should have
// * size is the bytes per file
// * isRand is whether the contents of the files should be a random chunk (otherwise it's all zeros)
// * realFile will write to a TempFile, instead of an in memory buffer
func sizedTar(opts sizedOptions) io.Reader {
	var (
		fh  io.ReadWriter
		err error
	)
	if opts.realFile {
		fh, err = ioutil.TempFile("", "tarsum")
		if err != nil {
			return nil
		}
	} else {
		fh = bytes.NewBuffer([]byte{})
	}
	tarW := tar.NewWriter(fh)
	defer tarW.Close()
	for i := int64(0); i < opts.num; i++ {
		err := tarW.WriteHeader(&tar.Header{
			Name: fmt.Sprintf("/testdata%d", i),
			Mode: 0755,
			Uid:  0,
			Gid:  0,
			Size: opts.size,
		})
		if err != nil {
			return nil
		}
		var rBuf []byte
		if opts.isRand {
			rBuf = make([]byte, 8)
			_, err = rand.Read(rBuf)
			if err != nil {
				return nil
			}
		} else {
			rBuf = []byte{0, 0, 0, 0, 0, 0, 0, 0}
		}

		for i := int64(0); i < opts.size/int64(8); i++ {
			tarW.Write(rBuf)
		}
	}
	return fh
}

// Generate generates a new archive from the content provided
// as input.
//
// `files` is a sequence of path/content pairs. A new file is
// added to the archive for each pair.
// If the last pair is incomplete, the file is created with an
// empty content. For example:
//
// Generate("foo.txt", "hello world", "emptyfile")
//
// The above call will return an archive with 2 files:
//  * ./foo.txt with content "hello world"
//  * ./empty with empty content
//
// FIXME: stream content instead of buffering
// FIXME: specify permissions and other archive metadata
func Generate(input ...string) (Archive, error) {
	files := parseStringPairs(input...)
	buf := new(bytes.Buffer)
	tw := tar.NewWriter(buf)
	for _, file := range files {
		name, content := file[0], file[1]
		hdr := &tar.Header{
			Name: name,
			Size: int64(len(content)),
		}
		if err := tw.WriteHeader(hdr); err != nil {
			return nil, err
		}
		if _, err := tw.Write([]byte(content)); err != nil {
			return nil, err
		}
	}
	if err := tw.Close(); err != nil {
		return nil, err
	}
	return ioutil.NopCloser(buf), nil
}

func fakeTar() (io.Reader, error) {
	uid := os.Getuid()
	gid := os.Getgid()

	content := []byte("Hello world!\n")
	buf := new(bytes.Buffer)
	tw := tar.NewWriter(buf)
	for _, name := range []string{"/etc/postgres/postgres.conf", "/etc/passwd", "/var/log/postgres/postgres.conf"} {
		hdr := new(tar.Header)

		// Leaving these fields blank requires root privileges
		hdr.Uid = uid
		hdr.Gid = gid

		hdr.Size = int64(len(content))
		hdr.Name = name
		if err := tw.WriteHeader(hdr); err != nil {
			return nil, err
		}
		tw.Write([]byte(content))
	}
	tw.Close()
	return buf, nil
}