// precalcNextBuf follows the next link in line and loads it from the DAGService,
// setting the next buffer to read from
func (dr *DagReader) precalcNextBuf() error {
if dr.position >= len(dr.node.Links) {
return io.EOF
}
nxt, err := dr.node.Links[dr.position].GetNode(dr.serv)
if err != nil {
return err
}
pb := new(ftpb.Data)
err = proto.Unmarshal(nxt.Data, pb)
if err != nil {
return err
}
dr.position++
switch pb.GetType() {
case ftpb.Data_Directory:
// A directory should not exist within a file
return ft.ErrInvalidDirLocation
case ftpb.Data_File:
//TODO: this *should* work, needs testing first
log.Warning("Running untested code for multilayered indirect FS reads.")
subr, err := NewDagReader(nxt, dr.serv)
if err != nil {
return err
}
dr.buf = subr
return nil
case ftpb.Data_Raw:
dr.buf = bytes.NewBuffer(pb.GetData())
return nil
default:
return ft.ErrUnrecognizedType
}
}
func DataSize(data []byte) (uint64, error) {
pbdata := new(pb.Data)
err := proto.Unmarshal(data, pbdata)
if err != nil {
return 0, err
}
switch pbdata.GetType() {
case pb.Data_Directory:
return 0, errors.New("Cant get data size of directory!")
case pb.Data_File:
return pbdata.GetFilesize(), nil
case pb.Data_Raw:
return uint64(len(pbdata.GetData())), nil
default:
return 0, errors.New("Unrecognized node data type!")
}
}
// 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(n *mdag.Node, serv mdag.DAGService) (io.Reader, error) {
pb := new(ftpb.Data)
err := proto.Unmarshal(n.Data, pb)
if err != nil {
return nil, err
}
switch pb.GetType() {
case ftpb.Data_Directory:
// Dont allow reading directories
return nil, ErrIsDir
case ftpb.Data_File:
return &DagReader{
node: n,
serv: serv,
buf: bytes.NewBuffer(pb.GetData()),
}, nil
case ftpb.Data_Raw:
// Raw block will just be a single level, return a byte buffer
return bytes.NewBuffer(pb.GetData()), nil
default:
return nil, ft.ErrUnrecognizedType
}
}