Re: Throwing exception in constructor causes segfault

[Andreas Schwab <schwab@suse.de>]

Craig Rodrigues <rodrigc@attbi.com> writes:

|> On Sat, Feb 23, 2002 at 09:56:48PM +0100, Andreas Schwab wrote:
|> > The problem is that operator delete[]() is receiving a different address
|> > than returned by operator new[]().  It looks like it is not adjusted for
|> > the cookie.
|> 
|> I don't understand the gcc exception handling code, so
|> can you explain this in more detail?   What is a cookie
|> in this case?

The cookie is just the number of elements of the array that is placed at
the beginning of the memory allocated with new[].  This has nothing to do
with exceptions.  It is needed so that delete[] knows how often it has to
call the destructor.

|> Also, in my testcase, if you comment out the delete[] p; line,
|> the testcase will still segfault.  Looks like delete[] is
|> called in the stack unwind code for some reason, if you
|> don't call it yourself.

Yes, the unwinder deallocates the array, since the exception occures when
the memory is already allocated.

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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