Re: Weird Crash in
Re: Weird Crash in
- Subject: Re: Weird Crash in
- From: Laurent Daudelin <email@hidden>
- Date: Fri, 17 Jun 2011 15:48:35 -0700
On Jun 17, 2011, at 15:22, Greg Parker wrote:
> On Jun 17, 2011, at 2:40 PM, Laurent Daudelin wrote:
>> One of my user sent me a crash log with an excerpt here:
>>
>> ...
>> Exception Type: EXC_BAD_ACCESS (SIGSEGV)
>> Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000027
>> ...
>> Thread 4 Crashed: Dispatch queue: com.apple.root.default-priority
>> 0 libobjc.A.dylib 0x00007fff85ea115c objc_msgSend_vtable2 + 12
>> 1 com.apple.Foundation 0x00007fff827f79a5 -[NSCFString isEqualToString:] + 63
>> ...
>>
>> It's a part of my code that compares NSStrings. Of course, nobody besides him are able to reproduce this.
>>
>> My question: what could cause a crash in function 'objc_msgSend_vtable2'?
>
> Short answer: for any of the same reasons that cause a crash in objc_msgSend().
>
> The vtable versions of objc_msgSend() are specialized optimizations for a few of the most frequently-called methods. objc_msgSend_vtable2 is currently optimizing the -class method. Presumably one of the two string objects was invalid and -isEqualToString: was trying to check which class the bad object belonged to.
Thanks for the speedy reply, Greg. What do you mean exactly by "invalid"? Bad pointers? Pointers on instances of different classes? Or both?
-Laurent.
--
Laurent Daudelin
AIM/iChat/Skype:LaurentDaudelin http://www.nemesys-soft.com/
Logiciels Nemesys Software email@hidden
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