[podman-remote] Fix closed connection on pull causes service panic

pkg/channel/writer.go

@@ -1,6 +1,7 @@
 package channel
 
 import (
+	"fmt"
 	"io"
 	"sync"
 
@@ -32,16 +33,24 @@ func (w *writeCloser) Chan() <-chan []byte {
 }
 
 // Write method for WriteCloser
-func (w *writeCloser) Write(b []byte) (int, error) {
+func (w *writeCloser) Write(b []byte) (bLen int, err error) {
+	// https://github.com/containers/podman/issues/7896
+	// when podman-remote pull image, if it was killed, the server will panic: send on closed channel
+	// so handle it
+	defer func() {
+		if rErr := recover(); rErr != nil {
+			err = fmt.Errorf("%s", rErr)
+		}
+	}()
 	if w == nil || w.ch == nil {
 		return 0, errors.New("use channel.NewWriter() to initialize a WriteCloser")
 	}
 
 	w.mux.Lock()
+	defer w.mux.Unlock()
 	buf := make([]byte, len(b))
 	copy(buf, b)
 	w.ch <- buf
-	w.mux.Unlock()
 
 	return len(b), nil
 }