Ain’t work! Will crash if an Object derivative showed up.

I am scanning ALL loaded classes and only subclasses of a certain class is 
interested. But due to the nature of this class scanning before I can make sure 
that the class derives from NSObject I cannot call any method on it.

> On Dec 14, 2014, at 03:34, Gary L. Wade <garyw...@desisoftsystems.com> wrote:
> 
> If all you care about is if an object is a proxy or not, look at isProxy.
> --
> Gary L. Wade (Sent from my iPad)
> http://www.garywade.com/
> 
>> On Dec 13, 2014, at 11:06 AM, Maxthon Chan <m...@maxchan.info> wrote:
>> 
>> What I am doing here is scanning all loaded classes for subclasses of a 
>> certain class. Before any NSObject method can be issued I have to check if 
>> it is actually NSObject or NSProxy derivative instead of an Object 
>> derivative that does not support NSObject methods. This calls for runtime 
>> equivalent for one of the following NSObject methods:
>> 
>> - [NSObject respondsToSelector:(SEL)aSelector] = 
>> class_respondsToSelector(Class, SEL) // this crashed.
>> + [NSObject conformsToProtocol:(Protocol *)aProtocol] = 
>> class_conformsToProtocol(Class, Protocol *) // check for NSObject protocol, 
>> this does not work.
>> + [NSObject isSubclassOfClass:(Class)aClass] // no equivalent, have to 
>> implement it myself
>> 
>> I ended up creating this:
>> 
>> BOOL class_isSubclassOfClass(Class cls, Class other)
>> {
>>   for (Class c = cls; c; c = class_getSuperclass(c))
>>       if (c == other)
>>           return YES;
>>   return NO;
>> }
>> 
>> If i remembered it right GNUstep runtime have this function. I will file a 
>> bug report to Apple and ask them to add this, as it is useful in class 
>> scanning and i am using this technique heavily in jailbreak detection.
>> 
>>> On Dec 14, 2014, at 01:20, Kyle Sluder <k...@ksluder.com> wrote:
>>> 
>>> On Sat, Dec 13, 2014, at 10:19 AM, Phillip Mills wrote:
>>>> Why do you think the problem is with “respondsToSelector:”?  The error
>>>> says you’re accessing past the end of a string.
>>> 
>>> Because the crash happens in a call stack that originates in
>>> class_respondsToSelector, and involves none of Maxthon's code.
>>> 
>>> --Kyle Sluder

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