Mail Archives: cygwin/2006/03/16/14:03:55
Ah, got it--it behaves like exception handling, but it
doesn't *look* like exception handling. Seems like a
good place to add some comments! ;-) (Offer to submit
a patch, but seeing as I had to ask, I doubt I'm the
right person to do so.) Thanks for clearing this up
for me!
-Norton
On 16 March 2006, Dave Korn wrote:
> On 16 March 2006 15:48, Norton Allen wrote:
>
>
>>>> * thread.cc (verifyable_object_isvalid): check for
>>>> NULL object or reference
>>>
>>> The "efault.faulted()" two lines above your change is supposed to catch
>>> NULL dereferences.
>>
>> Whoa! This looks like voodoo action-at-a-distance.
>
> Exception handling does that :) See also setjmp/longjmp.
>
>> efault.faulted()
>> doesn't even get passed the pointer to know whether or not it's
>> NULL.
>
> errno doesn't get passed any pointers, but it still often ends up returning
> 'EINVAL' when the pointer you pass to a routine is null....
>
>> Although efault.faulted() is supposed to catch the NULL dereferences,
>
> Nope, the exception handling is supposed to catch the NULL deref, and set an
> error code which is then returned by efault.faulted.
>
> Take a /look/ at the source for myfault::faulted in cygtls.h, it calls out
> to _cygtls::setup_fault, which calls _sjfault, which appears to be a q'n'd
> hacked-up version of setjmp in a context where it's going to get called back
> by an SEH handler. So IIUIC, calling 'efault.faulted' will catch any
> exception that happens from the point of the call until the point where the
> efault object goes out of scope and gets destructed and will cause execution
> to jump back to the if... clause.
>
>
>
>
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