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Re: [PATCH][BZ #16004] Check overlaps in memcpy_chk.
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: OndÅej BÃlka <neleai at seznam dot cz>
- Cc: <libc-alpha at sourceware dot org>
- Date: Mon, 21 Oct 2013 17:50:12 +0000
- Subject: Re: [PATCH][BZ #16004] Check overlaps in memcpy_chk.
- Authentication-results: sourceware.org; auth=none
- References: <20131005133423 dot GA8405 at domone> <Pine dot LNX dot 4 dot 64 dot 1310051925240 dot 9147 at digraph dot polyomino dot org dot uk> <20131021171406 dot GA27539 at domone dot podge>
On Mon, 21 Oct 2013, Ondrej Bilka wrote:
> On Sat, Oct 05, 2013 at 07:28:27PM +0000, Joseph S. Myers wrote:
> > There are tests for *_chk functions in debug/. If you add a new check you
> > should also add testcases for it to confirm that the error is caught at
> > runtime. This does of course require also adding the same check to the
> > generic version of the function, and in the case of memcpy_chk to the x86
> > (32-bit) versions as well.
> It also requires to edit compile time check. I spend hour trying to
> write testcase and wondering where is error until I realized that it got
> optimized away at compile time.
I'm not clear what compile-time check you're referring to. If it's
something in GCC, it's certainly reasonable to build testcases with
-fno-builtin-<function>. But really, if the error can be detected at
compile time, GCC should be able to do so - and for examples that can't be
detected at compile time, you can always use "volatile" to ensure the
compiler has no information about the actual values of function arguments.
Joseph S. Myers