Method doDownload

tq/ssh.go:213–284

doDownload starts a download. f is expected to be an existing file open in RW mode

(t *Transfer, workerNum int, f *os.File, cb ProgressCallback)

// doDownload starts a download. f is expected to be an existing file open in RW mode
func (a *SSHAdapter) doDownload(t *Transfer, workerNum int, f *os.File, cb ProgressCallback) error {
	args := a.argumentsForTransfer(t, "download")
	conn, err := a.transfer.Connection(workerNum)
	if err != nil {
		return err
	}
	conn.Lock()
	defer conn.Unlock()
	err = conn.SendMessage(fmt.Sprintf("get-object %s", t.Oid), args)
	if err != nil {
		return err
	}
	status, args, data, err := conn.ReadStatusWithData()
	if err != nil {
		return err
	}
	if status < 200 || status > 299 {
		buffer := &bytes.Buffer{}
		if data != nil {
			io.CopyN(buffer, data, 1024)
			io.Copy(io.Discard, data)
		}
		return errors.NewRetriableError(errors.New(tr.Tr.Get("got status %d when fetching OID %s: %s", status, t.Oid, buffer.String())))
	}

	var actualSize int64
	seenSize := false
	for _, arg := range args {
		if strings.HasPrefix(arg, "size=") {
			if seenSize {
				return errors.NewProtocolError(tr.Tr.Get("unexpected size argument"), nil)
			}
			actualSize, err = strconv.ParseInt(arg[5:], 10, 64)
			if err != nil || actualSize < 0 {
				return errors.NewProtocolError(tr.Tr.Get("expected valid size, got %q", arg[5:]), err)
			}
			seenSize = true
		}
	}
	if !seenSize {
		return errors.NewProtocolError(tr.Tr.Get("no size argument seen"), nil)
	}

	dlfilename := f.Name()
	// Wrap callback to give name context
	ccb := func(totalSize int64, readSoFar int64, readSinceLast int) error {
		if cb != nil {
			return cb(t.Name, totalSize, readSoFar, readSinceLast)
		}
		return nil
	}
	hasher := tools.NewHashingReader(data)
	written, err := tools.CopyWithCallback(f, hasher, t.Size, ccb)
	if err != nil {
		return errors.Wrap(err, tr.Tr.Get("cannot write data to temporary file %q", dlfilename))
	}

	if actual := hasher.Hash(); actual != t.Oid {