diff --git a/inc/Maat_rule.h b/inc/Maat_rule.h
index 8e499aa..bea7e76 100644
--- a/inc/Maat_rule.h
+++ b/inc/Maat_rule.h
@@ -243,13 +243,18 @@ void Maat_clean_status(scan_status_t* mid);
 typedef void*  MAAT_RULE_EX_DATA;
 // The idx parameter is the index: this will be the same value returned by Maat_rule_get_ex_new_index() when the functions were initially registered.
 // Finally the argl and argp parameters are the values originally passed to the same corresponding parameters when Maat_rule_get_ex_new_index() was called.
-typedef void Maat_rule_EX_new_func_t(int idx, const struct Maat_rule_t* rule, const char* srv_def_large, MAAT_RULE_EX_DATA* ad, long argl, void *argp);
-typedef void Maat_rule_EX_free_func_t(int idx, const struct Maat_rule_t* rule, const char* srv_def_large, MAAT_RULE_EX_DATA* ad, long argl, void *argp);
+typedef void Maat_rule_EX_new_func_t(int idx, const struct Maat_rule_t* rule, const char* srv_def_large,
+											MAAT_RULE_EX_DATA* ad, long argl, void *argp);
+typedef void Maat_rule_EX_free_func_t(int idx, const struct Maat_rule_t* rule, const char* srv_def_large,
+											MAAT_RULE_EX_DATA* ad, long argl, void *argp);
+typedef void Maat_rule_EX_dup_func_t(int idx,	MAAT_RULE_EX_DATA *to, MAAT_RULE_EX_DATA *from, long argl, void *argp);
 
 int Maat_rule_get_ex_new_index(Maat_feather_t feather, const char* compile_table_name,
-										 Maat_rule_EX_new_func_t *new_func,
+										 Maat_rule_EX_new_func_t* new_func,
 										 Maat_rule_EX_free_func_t* free_func,
+										 Maat_rule_EX_dup_func_t* dup_func,
 										 long argl, void *argp);
+//returned data is duplicated by dup_func of Maat_rule_get_ex_new_index,  caller is responsible to free the data.
 MAAT_RULE_EX_DATA Maat_rule_get_ex_data(Maat_feather_t feather, const struct Maat_rule_t* rule, int idx);
 
 
diff --git a/src/entry/Maat_api.cpp b/src/entry/Maat_api.cpp
index 5053f2e..c0d6ab5 100644
--- a/src/entry/Maat_api.cpp
+++ b/src/entry/Maat_api.cpp
@@ -980,6 +980,7 @@ void rule_ex_data_new_cb(const uchar * key, uint size, void * data, void * user)
 int Maat_rule_get_ex_new_index(Maat_feather_t feather, const char* compile_table_name,
 										 Maat_rule_EX_new_func_t *new_func,
 										 Maat_rule_EX_free_func_t* free_func,
+										 Maat_rule_EX_dup_func_t* dup_func,
 										 long argl, void *argp)
 {
 	struct _Maat_feather_t *_feather=(struct _Maat_feather_t *)feather;
@@ -1008,6 +1009,8 @@ int Maat_rule_get_ex_new_index(Maat_feather_t feather, const char* compile_table
 	p_table->ex_desc[idx].argp=argp;
 	p_table->ex_desc[idx].new_func=new_func;
 	p_table->ex_desc[idx].free_func=free_func;
+	p_table->ex_desc[idx].dup_func=dup_func;
+
 	p_table->ex_data_num++;
 	MESA_htable_iterate(_feather->scanner->compile_hash, rule_ex_data_new_cb, p_table->ex_desc+idx);
 failed:
@@ -1019,15 +1022,18 @@ MAAT_RULE_EX_DATA Maat_rule_get_ex_data(Maat_feather_t feather, const struct Maa
 {
 	struct _Maat_feather_t *_feather=(struct _Maat_feather_t *)feather;
 	struct _Maat_compile_inner_t *compile_inner=NULL;
+	const struct compile_ex_data_idx* ex_desc=NULL;	
 	MAAT_RULE_EX_DATA ad=NULL;
+	
 	compile_inner=(struct _Maat_compile_inner_t *)HASH_fetch_by_id(_feather->scanner->compile_hash, rule->config_id);
 	if(compile_inner==NULL)
 	{
 		return NULL;
 	}
 	pthread_rwlock_rdlock(&(compile_inner->rwlock));
-	assert(idx<compile_inner->ref_table->ex_data_num);
-	ad=compile_inner->ads[idx];
+	assert(idx<compile_inner->ref_table->ex_data_num);	
+	ex_desc=compile_inner->ref_table->ex_desc+idx;
+	ex_desc->dup_func(ex_desc->idx, &ad, compile_inner->ads+idx, ex_desc->argl,ex_desc->argp);
 	pthread_rwlock_unlock(&(compile_inner->rwlock));		
 	return ad;
 }
diff --git a/src/inc_internal/Maat_rule_internal.h b/src/inc_internal/Maat_rule_internal.h
index 53b8acf..6f95eec 100644
--- a/src/inc_internal/Maat_rule_internal.h
+++ b/src/inc_internal/Maat_rule_internal.h
@@ -94,6 +94,7 @@ struct compile_ex_data_idx
 {
 	Maat_rule_EX_new_func_t *new_func;
 	Maat_rule_EX_free_func_t* free_func;
+	Maat_rule_EX_dup_func_t* dup_func;
 	long argl;
 	void *argp;
 	int idx;