fix: fix writer

Author: yang.yu

README.md

@@ -42,10 +42,15 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 ```go
 func ReadAndWrite() {
-    resp := NewSmbNegotiateResponseV2()
-	stream := kaitai.NewReadWriteStream(kaitai.NewStream(reader))
-	resp.Read(stream, nil, resp)
-	// stream.Check()
-	err = stream.Write()
+	// read
+	stream := kaitai.NewStream(kaitai.NewFakeWriter(reader))
+	resp := drda.NewDrda()
+	err = resp.Read(stream, nil, resp)
+
+	// write
+	writer := buffer.NewSeekableBuffer()
+	err = resp.Check()
+	assert.Nil(err)
+	err = resp.Write(kaitai.NewStream(writer))
 }
 ```

kaitai/util.go

@@ -3,6 +3,7 @@ package kaitai
 import (
 	"bytes"
 	"compress/zlib"
+	"errors"
 	"io"
 	"math/bits"
 	"strings"
@@ -123,3 +124,15 @@ func ByteArrayIndexof(arr []byte, b byte) int {
 	}
 	return -1
 }
+
+type FakeWriter struct {
+	io.ReadSeeker
+}
+
+func (fw *FakeWriter) Write([]byte) (n int, err error) {
+	return 0, errors.New("unsupported write")
+}
+
+func NewFakeWriter(reader io.ReadSeeker) io.ReadWriteSeeker {
+	return &FakeWriter{reader}
+}

kaitai/writer.go

@@ -22,56 +22,3 @@ func (h *WriteBackHandler) writeBack(parent *Stream) error {
 	}
 	return h.handler(parent)
 }
-
-type ReadWriteTrait interface {
-	FetchInstances() error
-	WriteSeq() error
-	Check() error
-}
-
-type ReadWriteStream struct {
-	Stream
-
-	FetchInstance func() error
-	WriteSeq      func() error
-	Check         func() error
-}
-
-func NewReadWriteStream(stream *Stream) *ReadWriteStream {
-	return &ReadWriteStream{
-		Stream: *stream,
-	}
-}
-
-func (k *ReadWriteStream) setFetchInstanceHandler(handler func() error) {
-	k.FetchInstance = handler
-}
-
-func (k *ReadWriteStream) setWriteSeqHandler(handler func() error) {
-	k.WriteSeq = handler
-}
-
-func (k *ReadWriteStream) setCheckHandler(handler func() error) {
-	k.Check = handler
-}
-
-func (k *ReadWriteStream) Write(rt ReadWriteTrait) error {
-	k.setFetchInstanceHandler(rt.FetchInstances)
-	k.setWriteSeqHandler(rt.WriteSeq)
-	k.setCheckHandler(rt.Check)
-
-	err := k.Check()
-	if err != nil {
-		return err
-	}
-	err = k.WriteSeq()
-	if err != nil {
-		return err
-	}
-	err = k.FetchInstance()
-	if err != nil {
-		return err
-	}
-	err = k.WriteBackChildStreams()
-	return err
-}