On Wed, Mar 13, 2002 at 01:57:33PM -0800, Stephen Weeks wrote: > I don't think this explanation is correct. I still think that mmap is > returning a pointer to an invalid chunk of memory. To demonstrate > this, here is a program that does an mmap, fprintf, and then attempts > to write to the first byte of the mmap'ed memory.
The explanation wasn't quite correct, you're right, but the memory is not invalid. It's correctly returned by MapViewOfFileEx and the same value is returned by mmap(). However, it's *non-accessible* since all pages are protected using PAGE_NOACCESS after the call to MapViewOfFileEx. The next call to VirtualProtect which is responsible for setting the correct protection mode on the used memory (used mem != allocated mem) unfortunately fails. The result is that mmap() returns a correct memory pointer which is nevertheless inaccessible. :-( Anyway, I've checked in a patch. It now checks if VirtualProtect failed and then mmap() also fails. Try the next developers snapshot, please. Thanks for the testcases, Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Developer mailto:[EMAIL PROTECTED] Red Hat, Inc. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Bug reporting: http://cygwin.com/bugs.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
