sn/storage: Fix unclosed compressed files in FSTree

pkg/local_object_storage/blobstor/fstree/head.go

@@ -146,33 +146,36 @@ func (t *FSTree) readHeaderAndPayload(f io.ReadCloser, initial []byte) (*object.
 // and returns the object along with a reader for the remaining data.
 // This function takes ownership of the io.ReadCloser and will close it if it does not return it.
 func (t *FSTree) readUntilPayload(f io.ReadCloser, initial []byte) (*object.Object, io.ReadSeekCloser, error) {
-	reader := f
+	reader := io.Reader(f)
+	closer := io.Closer(f)
 
 	if t.IsCompressed(initial) {
 		decoder, err := zstd.NewReader(io.MultiReader(bytes.NewReader(initial), f))
 		if err != nil {
+			_ = closer.Close()
 			return nil, nil, fmt.Errorf("zstd decoder: %w", err)
 		}
-		reader = decoder.IOReadCloser()
+		reader = decoder
+		closer = zstdCloser{dec: decoder, cls: closer}
 
 		buf := make([]byte, object.MaxHeaderLen)
 		n, err := decoder.Read(buf)
 		if err != nil && !errors.Is(err, io.EOF) {
-			decoder.Close()
+			closer.Close()
 			return nil, nil, fmt.Errorf("zstd read: %w", err)
 		}
 		initial = buf[:n]
 	}
 
 	obj, payloadPrefix, err := objectwire.ExtractHeaderAndPayload(initial)
 	if err != nil {
-		_ = reader.Close()
+		_ = closer.Close()
 		return nil, nil, fmt.Errorf("extract header and payload: %w", err)
 	}
 
 	return obj, &payloadReader{
 		Reader: io.MultiReader(bytes.NewReader(payloadPrefix), reader),
-		close:  reader.Close,
+		close:  closer.Close,
 	}, nil
 }
 

pkg/local_object_storage/blobstor/fstree/util.go

@@ -0,0 +1,17 @@
+package fstree
+
+import (
+	"io"
+
+	"github.com/klauspost/compress/zstd"
+)
+
+type zstdCloser struct {
+	dec *zstd.Decoder
+	cls io.Closer
+}
+
+func (x zstdCloser) Close() error {
+	x.dec.Close()
+	return x.cls.Close()
+}