desgard / ios-source-probe Goto Github PK

// Prevent a deadlock between the weak reference machinery
    // and the +initialize machinery by ensuring that no 
    // weakly-referenced object has an un-+initialized isa.
    if (haveNew  &&  newObj) {
        Class cls = newObj->getIsa();
        if (cls != previouslyInitializedClass  &&  
            !((objc_class *)cls)->isInitialized()) 
        {
            SideTable::unlockTwo<haveOld, haveNew>(oldTable, newTable);
            _class_initialize(_class_getNonMetaClass(cls, (id)newObj));

            // If this class is finished with +initialize then we're good.
            // If this class is still running +initialize on this thread 
            // (i.e. +initialize called storeWeak on an instance of itself)
            // then we may proceed but it will appear initializing and 
            // not yet initialized to the check above.
            // Instead set previouslyInitializedClass to recognize it on retry.
            previouslyInitializedClass = cls;

            goto retry;
        }
    }