Re: 2.6.28 headers break kbd and net-tools userspace builds

From: Jan Engelhardt
Date: Tue Jan 27 2009 - 05:45:08 EST

On Tuesday 2009-01-27 06:08, David Miller wrote:
>> On Thu, Jan 22, 2009 at 07:03:29PM +0000, Andrew Walrond wrote:
>> > $ grep -r iphdr /usr/include/
>> >
>> > /usr/include/netinet/ip.h:struct iphdr
>> > /usr/include/netinet/tcp.h: * This should be defined as MIN(512, IP_MSS
>> > - sizeof (struct tcpiphdr)).
>> > /usr/include/linux/if_tunnel.h: struct iphdr iph;
>> > /usr/include/linux/ip.h:struct iphdr {
>> >
>> > $ grep netinet/ip.h iptunnel.c
>> >
>> > #include <netinet/ip.h>
>> >
>> > So linux/ip.h is clashing with glibc(2.8)'s netinet/ip.h
>> I took a look at my netinet/ip.h and this is obviously
>> the same structure.
>> But I do not know what the right answer is here.
>> This may be a general thing. Because iphdr is
>> no a kernel thing, it is an IP thing. So one could argue
>> that the kernel should not export it in the first place.
>The fly in the ointment is linux/if_tunnel.h
>We export a structure there for a userland interface which
>uses "struct iphdr".
>Because of that, we are faced with the difficult choice between
>defining the structure (as we do) in linux/ip.h or using some ugly
>__KERNEL__ ifdefs in linux/if_tunnel.h to conditionally include
>netinet/ip.h instead. :-/
>Really, I have no idea what to do about this as the problem has
>existed for so long.

I think in the long term, exported structs should probably
have a "kernel_" prefix, much like userspace libraries use
such prefixes to (try to) guard against simple name clashes.

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