Re: Weird Crash in
Re: Weird Crash in
- Subject: Re: Weird Crash in
- From: Greg Parker <email@hidden>
- Date: Fri, 17 Jun 2011 15:22:43 -0700
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.
--
Greg Parker email@hidden Runtime Wrangler
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