X.on now allocates a new array for each new handler added, stops new …

…handlers being called for the event that's currently being handled (#2559)

ChangeLog

@@ -52,6 +52,7 @@
             Ensure that pretokenised Strings are loaded as Flat Strings when executed from a String in RAM
             E.nativeCall also checks to see if getting data as a flat string failed (could have caused segfault)
             Fix for regression after #2547 fix (left hand operand of maths with a valueOf method)
+            X.on now allocates a new array for each new handler added, stops new handlers being called for the event that's currently being handled (#2559)
 
      2v24 : Bangle.js2: Add 'Bangle.touchRd()', 'Bangle.touchWr()'
             Bangle.js2: After Bangle.showTestScreen, put Bangle.js into a hard off state (not soft off)

src/jswrap_object.c

@@ -890,22 +890,22 @@ void jswrap_object_on_X(JsVar *parent, JsVar *event, JsVar *listener, bool addFi
   JsVar *eventList = jsvFindChildFromVar(parent, eventName, true);
   jsvUnLock(eventName);
   JsVar *eventListeners = jsvSkipName(eventList);
-  // if no array, add it
-  if (jsvIsUndefined(eventListeners)) {
-    eventListeners = jsvNewEmptyArray();
-    jsvSetValueOfName(eventList, eventListeners);
-  }
-  jsvUnLock(eventList);
-  if (!eventListeners) return; // out of memory
-  // now have an array and we just add to it
+  /* create a *new* array with the items in the right order. We do this
+  so that if we're adding a handler to an while we're in a handler that's
+  executing that event, the handler we just added doesn't get called. */
+  JsVar *newEventListeners = 0;
   if (addFirst) { // add it first?
-    JsVar *elements = jsvNewArray(&listener, 1);
-    jswrap_array_unshift(eventListeners, elements);
-    jsvUnLock(elements);
+    newEventListeners = jsvNewArray(&listener, 1);
+    if (eventListeners) jsvArrayPushAll(newEventListeners, eventListeners, false);
   } else { // or add it at the end
-    jsvArrayPush(eventListeners, listener);
+    newEventListeners = jsvNewEmptyArray();
+    if (eventListeners) jsvArrayPushAll(newEventListeners, eventListeners, false);
+    jsvArrayPush(newEventListeners, listener);
   }
   jsvUnLock(eventListeners);
+  eventListeners = newEventListeners;
+  jsvSetValueOfName(eventList, eventListeners);
+  jsvUnLock2(eventList, eventListeners);
   /* Special case if we're a data listener and data has already arrived then
    * we queue an event immediately. */
   if (jsvIsStringEqual(event, "data")) {