Date: Thu, 6 Jul 2017 13:22:18 -0400 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Subject: Re: Documentation of memcpy and undefined behavior in memset On Thu, Jul 06, 2017 at 08:17:32PM +0300, Alexander Monakov wrote: > On Thu, 6 Jul 2017, Rich Felker wrote: > > > If p points to one past the end of an object that ends on a page > > boundary, this transformation could introduce a crash. > > The object beginning at p (i.e. the array beginning just after the > array which p was derived from) could be volatile, making that an > invalid transformation. Nothing gives the compiler a guarantee > that that area is non-volatile. I'm doubtful of this. Certainly passing a pointer to memcpy with a nonzero n is a guarantee that the pointed-to object is non-volatile. The n=0 case is less clear though. Rich
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