deal with empty param to serialize()

diff --git a/libs/esl/src/esl_oop.cpp b/libs/esl/src/esl_oop.cpp
index 1b6629c066be55d1d484ef6c3c64e4b323ca12bf..231950f892e9bb7cbc7fa9446808721462dc9d25 100644 (file)
--- a/libs/esl/src/esl_oop.cpp
+++ b/libs/esl/src/esl_oop.cpp
@@ -355,7 +355,7 @@ const char *ESLevent::serialize(const char *format)
                return "";
        }
 
-       if (!strcasecmp(format, "json")) {
+       if (format && !strcasecmp(format, "json")) {
                esl_event_serialize_json(event, &serialized_string);
                return serialized_string;
        }