[#7575] use memory+file buffer when rereading the request body (fix #7572)

apis/batch.go

@@ -364,6 +364,7 @@ func processInternalRequest(
 	// assign request
 	event.Request = r
 	event.Request.Body = &router.RereadableReadCloser{ReadCloser: r.Body} // enables multiple reads
+	defer event.Request.Body.Close()
 
 	// assign response
 	rec := httptest.NewRecorder()

apis/middlewares_body_limit.go

@@ -112,9 +112,21 @@ func (r *limitedReader) Read(b []byte) (int, error) {
 	return n, nil
 }
 
+// explicit casts to ensure that the main struct methods will be invoked
+// (extra precautions in case of nested interface wrapping erasure)
+// ---
+
 func (r *limitedReader) Reread() {
-	rr, ok := r.ReadCloser.(router.Rereader)
+	rereader, ok := r.ReadCloser.(router.Rereader)
 	if ok {
-		rr.Reread()
+		rereader.Reread()
 	}
 }
+
+func (r *limitedReader) Close() error {
+	closer, ok := r.ReadCloser.(io.Closer)
+	if ok {
+		return closer.Close()
+	}
+	return nil
+}