Make unixio.DagReader an interface

License: MIT
Signed-off-by: Jakub Sztandera <kubuxu@protonmail.ch>

core/coreunix/cat.go

@@ -8,7 +8,7 @@ import (
 	uio "github.com/ipfs/go-ipfs/unixfs/io"
 )
 
-func Cat(ctx context.Context, n *core.IpfsNode, pstr string) (*uio.DagReader, error) {
+func Cat(ctx context.Context, n *core.IpfsNode, pstr string) (uio.DagReader, error) {
 	dagNode, err := core.Resolve(ctx, n.Namesys, n.Resolver, path.Path(pstr))
 	if err != nil {
 		return nil, err

unixfs/io/dagreader.go

@@ -20,8 +20,15 @@ var ErrIsDir = errors.New("this dag node is a directory")
 
 var ErrCantReadSymlinks = errors.New("cannot currently read symlinks")
 
+type DagReader interface {
+	ReadSeekCloser
+	Size() uint64
+	CtxReadFull(context.Context, []byte) (int, error)
+	Offset() int64
+}
+
 // DagReader provides a way to easily read the data contained in a dag.
-type DagReader struct {
+type pbDagReader struct {
 	serv mdag.DAGService
 
 	// the node being read
@@ -59,10 +66,10 @@ type ReadSeekCloser interface {
 
 // NewDagReader creates a new reader object that reads the data represented by
 // the given node, using the passed in DAGService for data retreival
-func NewDagReader(ctx context.Context, n node.Node, serv mdag.DAGService) (*DagReader, error) {
+func NewDagReader(ctx context.Context, n node.Node, serv mdag.DAGService) (DagReader, error) {
 	switch n := n.(type) {
 	case *mdag.RawNode:
-		return &DagReader{
+		return &pbDagReader{
 			buf: NewRSNCFromBytes(n.RawData()),
 		}, nil
 	case *mdag.ProtoNode:
@@ -101,10 +108,10 @@ func NewDagReader(ctx context.Context, n node.Node, serv mdag.DAGService) (*DagR
 	}
 }
 
-func NewDataFileReader(ctx context.Context, n *mdag.ProtoNode, pb *ftpb.Data, serv mdag.DAGService) *DagReader {
+func NewDataFileReader(ctx context.Context, n *mdag.ProtoNode, pb *ftpb.Data, serv mdag.DAGService) *pbDagReader {
 	fctx, cancel := context.WithCancel(ctx)
 	promises := mdag.GetDAG(fctx, serv, n)
-	return &DagReader{
+	return &pbDagReader{
 		node:     n,
 		serv:     serv,
 		buf:      NewRSNCFromBytes(pb.GetData()),
@@ -117,7 +124,7 @@ func NewDataFileReader(ctx context.Context, n *mdag.ProtoNode, pb *ftpb.Data, se
 
 // precalcNextBuf follows the next link in line and loads it from the
 // DAGService, setting the next buffer to read from
-func (dr *DagReader) precalcNextBuf(ctx context.Context) error {
+func (dr *pbDagReader) precalcNextBuf(ctx context.Context) error {
 	dr.buf.Close() // Just to make sure
 	if dr.linkPosition >= len(dr.promises) {
 		return io.EOF
@@ -158,22 +165,22 @@ func (dr *DagReader) precalcNextBuf(ctx context.Context) error {
 		dr.buf = NewRSNCFromBytes(nxt.RawData())
 		return nil
 	default:
-		return errors.New("unrecognized node type in DagReader")
+		return errors.New("unrecognized node type in pbDagReader")
 	}
 }
 
 // Size return the total length of the data from the DAG structured file.
-func (dr *DagReader) Size() uint64 {
+func (dr *pbDagReader) Size() uint64 {
 	return dr.pbdata.GetFilesize()
 }
 
 // Read reads data from the DAG structured file
-func (dr *DagReader) Read(b []byte) (int, error) {
+func (dr *pbDagReader) Read(b []byte) (int, error) {
 	return dr.CtxReadFull(dr.ctx, b)
 }
 
 // CtxReadFull reads data from the DAG structured file
-func (dr *DagReader) CtxReadFull(ctx context.Context, b []byte) (int, error) {
+func (dr *pbDagReader) CtxReadFull(ctx context.Context, b []byte) (int, error) {
 	// If no cached buffer, load one
 	total := 0
 	for {
@@ -201,7 +208,7 @@ func (dr *DagReader) CtxReadFull(ctx context.Context, b []byte) (int, error) {
 	}
 }
 
-func (dr *DagReader) WriteTo(w io.Writer) (int64, error) {
+func (dr *pbDagReader) WriteTo(w io.Writer) (int64, error) {
 	// If no cached buffer, load one
 	total := int64(0)
 	for {
@@ -226,20 +233,20 @@ func (dr *DagReader) WriteTo(w io.Writer) (int64, error) {
 	}
 }
 
-func (dr *DagReader) Close() error {
+func (dr *pbDagReader) Close() error {
 	dr.cancel()
 	return nil
 }
 
-func (dr *DagReader) Offset() int64 {
+func (dr *pbDagReader) Offset() int64 {
 	return dr.offset
 }
 
 // Seek implements io.Seeker, and will seek to a given offset in the file
 // interface matches standard unix seek
 // TODO: check if we can do relative seeks, to reduce the amount of dagreader
 // recreations that need to happen.
-func (dr *DagReader) Seek(offset int64, whence int) (int64, error) {
+func (dr *pbDagReader) Seek(offset int64, whence int) (int64, error) {
 	switch whence {
 	case os.SEEK_SET:
 		if offset < 0 {

unixfs/io/dagreader_test.go

@@ -236,7 +236,7 @@ func TestReaderSzie(t *testing.T) {
 	}
 }
 
-func readByte(t testing.TB, reader *DagReader) byte {
+func readByte(t testing.TB, reader DagReader) byte {
 	out := make([]byte, 1)
 	c, err := reader.Read(out)
 

unixfs/mod/dagmodifier.go

@@ -43,7 +43,7 @@ type DagModifier struct {
 	curWrOff   uint64
 	wrBuf      *bytes.Buffer
 
-	read *uio.DagReader
+	read uio.DagReader
 }
 
 func NewDagModifier(ctx context.Context, from node.Node, serv mdag.DAGService, spl chunk.SplitterGen) (*DagModifier, error) {