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DateTue, 25 Feb 2003 15:46:46 -0800
SubjectInvalid compilation without -fno-strict-aliasing
FromJean Tourrilhes <>
	Hi,

	It looks like a compiler bug to me...
	Some users have complained that when the following code is
compiled without the -fno-strict-aliasing, the order of the write and
memcpy is inverted (which mean a bogus len is mem-copied into the
stream).
	Code (from linux/include/net/iw_handler.h) :
--------------------------------------------
static inline char *
iwe_stream_add_event(char *	stream,		/* Stream of events */
		     char *	ends,		/* End of stream */
		     struct iw_event *iwe,	/* Payload */
		     int	event_len)	/* Real size of payload */
{
	/* Check if it's possible */
	if((stream + event_len) < ends) {
		iwe->len = event_len;
		memcpy(stream, (char *) iwe, event_len);
		stream += event_len;
	}
	return stream;
}
--------------------------------------------
	IMHO, the compiler should have enough context to know that the
reordering is dangerous. Any suggestion to make this simple code more
bullet proof is welcomed.
	Have fun...

	Jean
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