Re: Redefinition of struct in6_addr in <netinet/in.h> and <linux/in6.h>

From: Carlos O'Donell
Date: Thu Jan 17 2013 - 23:22:11 EST


On Thu, Jan 17, 2013 at 11:20 PM, Mike Frysinger <vapier@xxxxxxxxxx> wrote:
> On Wednesday 16 January 2013 22:15:38 David Miller wrote:
>> From: Carlos O'Donell <carlos@xxxxxxxxxxxxxxxx>
>> Date: Wed, 16 Jan 2013 21:15:03 -0500
>>
>> > +/* If a glibc-based userspace has already included in.h, then we will
>> > not + * define in6_addr (nor the defines), sockaddr_in6, or ipv6_mreq.
>> > The + * ABI used by the kernel and by glibc match exactly. Neither the
>> > kernel + * nor glibc should break this ABI without coordination.
>> > + */
>> > +#ifndef _NETINET_IN_H
>> > +
>>
>> I think we should shoot for a non-glibc-centric solution.
>>
>> I can't imagine that other libc's won't have the same exact problem
>> with their netinet/in.h conflicting with the kernel's, redefining
>> structures like in6_addr, that we'd want to provide a protection
>> scheme for here as well.
>
> yes, the kernel's use of __GLIBC__ in exported headers has already caused
> problems in the past. fortunately, it's been reduced down to just one case
> now (stat.h). let's not balloon it back up.
> -mike

I also see coda.h has grown a __GLIBC__ usage.

In the next revision of the patch I created a single libc-compat.h header
which encompasses the logic for any libc that wants to coordinate with
the kernel headers.

It's simple enough to move all of the __GLIBC__ uses into libc-compat.h,
then you control userspace libc coordination from one file.

Cheers,
Carlos.
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