app_jsdt: restore JS stack after executing a function

src/modules/app_jsdt/app_jsdt_api.c

@@ -770,6 +770,7 @@ int app_jsdt_run_ex(sip_msg_t *msg, char *func, char *p1, char *p2,
 	int ret;
 	str txt;
 	sip_msg_t *bmsg;
+	duk_idx_t jtop;
 
 	if(_sr_J_env.JJ==NULL) {
 		LM_ERR("js loading state not initialized (call: %s)\n", func);
@@ -779,7 +780,8 @@ int app_jsdt_run_ex(sip_msg_t *msg, char *func, char *p1, char *p2,
 	jsdt_kemi_reload_script();
 
 	LM_DBG("executing js function: [[%s]]\n", func);
-	LM_DBG("js top index is: %d\n", duk_get_top(_sr_J_env.JJ));
+	jtop = duk_get_top(_sr_J_env.JJ);
+	LM_DBG("js top index is: %d\n", (int)jtop);
 	duk_get_global_string(_sr_J_env.JJ, func);
 	if(!duk_is_function(_sr_J_env.JJ, -1))
 	{
@@ -789,8 +791,10 @@ int app_jsdt_run_ex(sip_msg_t *msg, char *func, char *p1, char *p2,
 				duk_get_type(_sr_J_env.JJ, -1));
 			txt.s = (char*)duk_to_string(_sr_J_env.JJ, -1);
 			LM_ERR("error from JS: %s\n", (txt.s)?txt.s:"unknown");
+			duk_set_top(_sr_J_env.JJ, jtop);
 			return -1;
 		} else {
+			duk_set_top(_sr_J_env.JJ, jtop);
 			return 1;
 		}
 	}
@@ -840,15 +844,16 @@ int app_jsdt_run_ex(sip_msg_t *msg, char *func, char *p1, char *p2,
 				LM_ERR("error from js: unknown\n");
 			}
 		}
-		duk_pop(_sr_J_env.JJ);
 		if(n==1) {
+			duk_set_top(_sr_J_env.JJ, jtop);
 			return 1;
 		} else {
 			LM_ERR("error executing: %s (err: %d)\n", func, ret);
+			duk_set_top(_sr_J_env.JJ, jtop);
 			return -1;
 		}
 	}
-	duk_pop(_sr_J_env.JJ);
+	duk_set_top(_sr_J_env.JJ, jtop);
 
 	return 1;
 }