Force JSON & CBOR to be constructed from io.ReadSeeker

ipld · Feb 17, 2016 · ec90690 · ec90690
1 parent 94650a0
commit ec90690
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Showing 3 changed files with 22 additions and 32 deletions.
diff --git a/coding/cbor/stream.go b/coding/cbor/stream.go
@@ -25,7 +25,7 @@ func init() {
 }
 
 type CBORDecoder struct {
-	r   io.Reader
+	r   io.ReadSeeker
 	pos int64
 }
 
@@ -35,17 +35,12 @@ type cborParser struct {
 	tagStack []bool
 }
 
-func NewCBORDecoder(r io.Reader) (*CBORDecoder, error) {
-	s := r.(io.Seeker)
-	if s == nil {
-		return &CBORDecoder{r, -1}, nil
-	} else {
-		offset, err := s.Seek(0, 1)
-		if err != nil {
-			return nil, err
-		}
-		return &CBORDecoder{r, offset}, nil
+func NewCBORDecoder(r io.ReadSeeker) (*CBORDecoder, error) {
+	offset, err := r.Seek(0, 1)
+	if err != nil {
+		return nil, err
 	}
+	return &CBORDecoder{r, offset}, nil
 }
 
 func (d *CBORDecoder) Read(cb reader.ReadFun) error {
@@ -54,7 +49,7 @@ func (d *CBORDecoder) Read(cb reader.ReadFun) error {
 	} else if d.pos == -1 {
 		d.pos = -2
 	} else {
-		newoffset, err := d.r.(io.Seeker).Seek(d.pos, 0)
+		newoffset, err := d.r.Seek(d.pos, 0)
 		if err != nil {
 			return err
 		} else if newoffset != d.pos {

diff --git a/coding/coding.go b/coding/coding.go
@@ -20,8 +20,6 @@ const (
 	HeaderPath = "/mdagv1"
 )
 
-var StreamCodecs map[string]func(io.Reader) (stream.NodeReader, error)
-
 type Codec int
 
 const (
@@ -32,26 +30,28 @@ const (
 	CodecCBORNoTags
 )
 
+var StreamCodecs map[string]func(io.ReadSeeker) (stream.NodeReader, error)
+
 func init() {
 	Header = mc.Header([]byte(HeaderPath))
 
-	StreamCodecs = map[string]func(io.Reader) (stream.NodeReader, error){
-		json.HeaderPath: func(r io.Reader) (stream.NodeReader, error) {
+	StreamCodecs = map[string]func(io.ReadSeeker) (stream.NodeReader, error){
+		json.HeaderPath: func(r io.ReadSeeker) (stream.NodeReader, error) {
 			return json.NewJSONDecoder(r)
 		},
-		cbor.HeaderPath: func(r io.Reader) (stream.NodeReader, error) {
+		cbor.HeaderPath: func(r io.ReadSeeker) (stream.NodeReader, error) {
 			return cbor.NewCBORDecoder(r)
 		},
-		cbor.HeaderWithTagsPath: func(r io.Reader) (stream.NodeReader, error) {
+		cbor.HeaderWithTagsPath: func(r io.ReadSeeker) (stream.NodeReader, error) {
 			return cbor.NewCBORDecoder(r)
 		},
-		pb.MsgIOHeaderPath: func(r io.Reader) (stream.NodeReader, error) {
+		pb.MsgIOHeaderPath: func(r io.ReadSeeker) (stream.NodeReader, error) {
 			return pb.Decode(mc.WrapHeaderReader(pb.MsgIOHeader, r))
 		},
 	}
 }
 
-func Decode(r io.Reader) (stream.NodeReader, error) {
+func Decode(r io.ReadSeeker) (stream.NodeReader, error) {
 	// get multicodec first header, should be mcmux.Header
 	err := mc.ConsumeHeader(r, Header)
 	if err != nil {

diff --git a/coding/json/stream.go b/coding/json/stream.go
@@ -24,7 +24,7 @@ func init() {
 }
 
 type JSONDecoder struct {
-	r   io.Reader
+	r   io.ReadSeeker
 	pos int64
 }
 
@@ -33,17 +33,12 @@ type jsonParser struct {
 	decoder *json.Decoder
 }
 
-func NewJSONDecoder(r io.Reader) (*JSONDecoder, error) {
-	s := r.(io.Seeker)
-	if s == nil {
-		return &JSONDecoder{r, -1}, nil
-	} else {
-		offset, err := s.Seek(0, 1)
-		if err != nil {
-			return nil, err
-		}
-		return &JSONDecoder{r, offset}, nil
+func NewJSONDecoder(r io.ReadSeeker) (*JSONDecoder, error) {
+	offset, err := r.Seek(0, 1)
+	if err != nil {
+		return nil, err
 	}
+	return &JSONDecoder{r, offset}, nil
 }
 
 func (d *JSONDecoder) Read(cb reader.ReadFun) error {
@@ -52,7 +47,7 @@ func (d *JSONDecoder) Read(cb reader.ReadFun) error {
 	} else if d.pos == -1 {
 		d.pos = -2
 	} else {
-		newoffset, err := d.r.(io.Seeker).Seek(d.pos, 0)
+		newoffset, err := d.r.Seek(d.pos, 0)
 		if err != nil {
 			return err
 		} else if newoffset != d.pos {