Date: Mon, 6 Apr 2015 09:58:49 -0600 From: Warner Losh <imp@bsdimp.com> To: John-Mark Gurney <jmg@funkthat.com> Cc: freebsd-arm@FreeBSD.org Subject: Re: remove broken lib/libc/arm/string/memcpy_xscale.S Message-ID: <EBEF298E-38F7-49BA-8BFC-D8B61C0F0BBA@bsdimp.com> In-Reply-To: <20150405015245.GO51048@funkthat.com> References: <20150405015245.GO51048@funkthat.com>
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> On Apr 4, 2015, at 7:52 PM, John-Mark Gurney <jmg@funkthat.com> wrote:
>
> I would like to remove this file as it does not implement our defined
> memcpy. Per POSIX, overlapping regions passed to memcpy is undefined
> behavior. We have defined it to have the same symatics as memmove.
>
> Sample test program:
> #include <stdio.h>
> #include <string.h>
>
> char bufa[512] = "this is a test buffer that should be copied fine.";
> int
> main()
> {
>
> memcpy(&bufa[10], &bufa[0], strlen(&bufa[10]));
> printf("%s\n", bufa);
>
> return 0;
> }
>
> Output on amd64 HEAD:
> this is a this is a test buffer that should be co
>
> Output on old armv4 from 9.x:
> this is a this is a thst buffethst bufhould beufh
>
> If you just look at the file, it is clear that the implementation does
> not adjust the copy direction based upon pointers. We imported the
> code from NetBSD, and NetBSD does apparently require memcpy's arguments
> to be non-overlapping.
>
> I'll remove the file shortly unless someone can prove to me that all
> uses of memcpy in our tree do not depend upon our defined behavior
> per memcpy(3)'s man page.
Any chance you can fix this implementation instead?
Warner
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