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msgio.go
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msgio.go
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package msgio
import (
"encoding/binary"
"io"
)
var NBO = binary.BigEndian
type Writer interface {
WriteMsg([]byte) error
}
type WriteCloser interface {
Writer
io.Closer
}
type Reader interface {
ReadMsg([]byte) (int, error)
}
type ReadCloser interface {
Reader
io.Closer
}
type ReadWriter interface {
Reader
Writer
}
type ReadWriteCloser interface {
Reader
Writer
io.Closer
}
type Writer_ struct {
W io.Writer
}
func NewWriter(w io.Writer) WriteCloser {
return &Writer_{w}
}
func (s *Writer_) WriteMsg(msg []byte) (err error) {
length := uint32(len(msg))
if err := binary.Write(s.W, NBO, &length); err != nil {
return err
}
_, err = s.W.Write(msg)
return err
}
func (s *Writer_) Close() error {
if c, ok := s.W.(io.Closer); ok {
return c.Close()
}
return nil
}
type Reader_ struct {
R io.Reader
lbuf []byte
}
func NewReader(r io.Reader) ReadCloser {
return &Reader_{r, make([]byte, 4)}
}
func (s *Reader_) ReadMsg(msg []byte) (int, error) {
if _, err := io.ReadFull(s.R, s.lbuf); err != nil {
return 0, err
}
length := int(NBO.Uint32(s.lbuf))
if length < 0 || length > len(msg) {
return 0, io.ErrShortBuffer
}
_, err := io.ReadFull(s.R, msg[:length])
return length, err
}
func (s *Reader_) Close() error {
if c, ok := s.R.(io.Closer); ok {
return c.Close()
}
return nil
}
type ReadWriter_ struct {
Reader
Writer
}
func NewReadWriter(rw io.ReadWriter) ReadWriter {
return &ReadWriter_{
Reader: NewReader(rw),
Writer: NewWriter(rw),
}
}
func (rw *ReadWriter_) Close() error {
if w, ok := rw.Writer.(WriteCloser); ok {
return w.Close()
}
if r, ok := rw.Reader.(ReadCloser); ok {
return r.Close()
}
return nil
}