cri: support io by streaming api

Signed-off-by: Abel Feng <fshb1988@gmail.com>

core/transfer/streaming/reader.go

@@ -0,0 +1,121 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package streaming
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+
+	transferapi "github.com/containerd/containerd/api/types/transfer"
+	"github.com/containerd/containerd/v2/core/streaming"
+	"github.com/containerd/typeurl/v2"
+)
+
+type readByteStream struct {
+	ctx       context.Context
+	stream    streaming.Stream
+	window    int32
+	updated   chan struct{}
+	errCh     chan error
+	remaining []byte
+}
+
+func ReadByteStream(ctx context.Context, stream streaming.Stream) io.ReadCloser {
+	rbs := &readByteStream{
+		ctx:     ctx,
+		stream:  stream,
+		window:  0,
+		errCh:   make(chan error),
+		updated: make(chan struct{}, 1),
+	}
+	go func() {
+		for {
+			if rbs.window >= windowSize {
+				select {
+				case <-ctx.Done():
+					return
+				case <-rbs.updated:
+					continue
+				}
+			}
+			update := &transferapi.WindowUpdate{
+				Update: windowSize,
+			}
+			anyType, err := typeurl.MarshalAny(update)
+			if err != nil {
+				rbs.errCh <- err
+				return
+			}
+			if err := stream.Send(anyType); err == nil {
+				rbs.window += windowSize
+			} else if !errors.Is(err, io.EOF) {
+				rbs.errCh <- err
+			}
+		}
+
+	}()
+	return rbs
+}
+
+func (r *readByteStream) Read(p []byte) (n int, err error) {
+	plen := len(p)
+	if len(r.remaining) > 0 {
+		copied := copy(p, r.remaining)
+		if len(r.remaining) > plen {
+			r.remaining = r.remaining[plen:]
+		} else {
+			r.remaining = nil
+		}
+		return copied, nil
+	}
+	select {
+	case <-r.ctx.Done():
+		return 0, r.ctx.Err()
+	case err := <-r.errCh:
+		return 0, err
+	default:
+	}
+	anyType, err := r.stream.Recv()
+	if err != nil {
+		return 0, err
+	}
+	i, err := typeurl.UnmarshalAny(anyType)
+	if err != nil {
+		return 0, err
+	}
+	switch v := i.(type) {
+	case *transferapi.Data:
+		n := copy(p, v.Data)
+		if len(v.Data) > plen {
+			r.remaining = v.Data[plen:]
+		}
+		r.window = r.window - int32(n)
+		if r.window < windowSize {
+			r.updated <- struct{}{}
+		}
+		return n, nil
+	default:
+		return 0, fmt.Errorf("stream received error type %v", v)
+	}
+
+}
+
+func (r *readByteStream) Close() error {
+	return r.stream.Close()
+}