Date: Thu, 11 Oct 2012 00:36:27 -0400 (EDT) From: idunham@...abit.com To: musl@...ts.openwall.com Subject: Re: Clash between 'netinet/if_ether.h' and 'linux/if_ether.h' > On Wed, Oct 10, 2012 at 10:06:35PM +0200, Abdoulaye Walsimou GAYE wrote: >> On 10/09/2012 01:33 AM, Rich Felker wrote: >> >On Tue, Oct 09, 2012 at 12:45:17AM +0200, Abdoulaye Walsimou GAYE >> wrote: >> >>Hello, >> >>While trying to compile busybox-1.20.2, the following issue raised: >> >> >> >> CC networking/ifplugd.o >> >>In file included from >> /home/walsimou/embtoolkit.git/sysroot-armel-linux-arm920t/usr/include/net/ethernet.h:10:0, >> >> from networking/ifplugd.c:41: >> >>/home/walsimou/embtoolkit.git/sysroot-armel-linux-arm920t/usr/include/netinet/if_ether.h:75:8: >> error: redefinition of 'struct ethhdr' >> >>/home/walsimou/embtoolkit.git/sysroot-armel-linux-arm920t/usr/include/linux/if_ether.h:127:8: >> note: originally defined here >> >> >> >>Note that uClibc strategy here is to include linux/if_ether.h >> >It's a bug to be including linux/if_ether.h, and there's no way to >> >work around this without depending on kernel headers, which musl will >> >not do for two reasons: >> > >> >1. We can't control conformance issues and/or breakage if they expose >> >crap into the namespace that they shouldn't be exposing, and this >> >tends to vary by version. >> > >> >2. It makes it so you can't build or use musl without kernel headers. >> > >> >It should be a one-line patch to fix ifplugd. >> > >> >Rich >> >> >> Hi Rich, >> >> I understand your point to not pollute the namespace, but there is >> others files >> under linux/ doing #include <linux/if_ether.h>. >> >> linux/ethtool.h:17:#include <linux/if_ether.h> >> linux/if_tun.h:20:#include <linux/if_ether.h> >> linux/if_bonding.h:48:#include <linux/if_ether.h> >> linux/virtio_net.h:31:#include <linux/if_ether.h> >> linux/netfilter_bridge.h:8:#include <linux/if_ether.h> >> linux/bpqether.h:9:#include <linux/if_ether.h> >> linux/netdevice.h:29:#include <linux/if_ether.h> >> linux/if_fddi.h:12: * if_fddi.h is based on previous if_ether.h >> and if_tr.h work by >> linux/if_arcnet.h:20:#include <linux/if_ether.h> >> linux/atmlec.h:13:#include <linux/if_ether.h> >> linux/if_pppox.h:24:#include <linux/if_ether.h> >> linux/if_ether.h:8: * Version: @(#)if_ether.h 1.0.1a 02/08/94 >> linux/netfilter_bridge/ebtables.h:17:#include <linux/if_ether.h> >> >> >> Does it means all these files should not be used in userspace >> application beside netinet/if_ether.h? >> Or does it means that these files should not be exported to >> userspace headers or should include >> <netinet/if_ether.h> instead? >> If yes, then It's a bug and should be reported to upstream kernel >> network maintainers. > > I think it's a bug that should be reported to the upstream kernel > network maintainers. But I'm not sure what the right fix is. In > general, kernel headers should never define anything that clashes with > userspace headers. However, netinet/if_ether.h is not a "standard" > header by any standard I know of; it seems to have been invented by > glibc (correct me if I'm mistaken). In this case, if I'm right, it may It's in *BSD with a "(c) 1982,... Regents of the University of California" notice. So it was part of the original BSD networking stack. glibc has a strange mix of #include <linux/...> & copy-paste from the BSD headers. In summary, while it isn't standardized AFAICT, it's part of just about every *nix version in recent history (AIX, OS X, Solaris, Unixware, SCO OpenServer, OSF/1, Linux + *libc, Mach, Hurd, and probably a few more). My best guess is that the kernel developers needed it for the kernel network stack (hence <linux/if_ether.h>), and the libc developers included that copy to avoid exactly this issue. > actually be glibc that trampled namespace belonging to the kernel. > > With that said, as the headers currently stand, I think the code bug > is the act of including both netinet/if_ether.h and linux/if_ether.h > (or any other linux/ header that includes linux/if_ether.h). An > application should use _either_ the userspace _or_ the kernel headers > for this extended functionality, not both.
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