On 2024-08-20, at 13:28:22 +0200, Pablo Neira Ayuso wrote: > On Mon, Aug 19, 2024 at 07:24:06PM +0200, Pablo Neira Ayuso wrote: > > On Tue, Jul 09, 2024 at 01:05:45PM +0000, Joshua Lant wrote: > > > Error compiling with musl-libc: > > > The commit hash 810f8568f44f5863c2350a39f4f5c8d60f762958 introduces the > > > netinet/ether.h header into xtables.h, which causes an error due to the > > > redefinition of the ethhdr struct, defined in linux/if_ether.h and > > > netinet/ether.h. > > > > > > This is is a known issue with musl-libc, with kernel headers providing > > > guards against this happening when glibc is used: > > > https://wiki.musl-libc.org/faq (Q: Why am I getting “error: redefinition > > > of struct ethhdr/tcphdr/etc”?) > > > > > > The only value used from netinet/ether.h is ETH_ALEN, which is already set > > > manually in libxtables/xtables.c. Move this definition to the header and > > > eliminate the inclusion of netinet/if_ether.h. > > > > Any chance that musl headers are being used so this can be autodetected? > > Then, no option to pass -D__UAPI_DEF_ETHHDR=0 is required. > > To clarify, what I mean is if it is possible to autodetect that musl > headers are used, then add this definition. > > I'd prefer no new --option as you propose is required to handle this. There are a couple of approaches that I see. 1. Test whether netinet/if_ether.h sets `__UAPI_DEF_ETHHDR` to zero (in which case we are building with musl): saved_CPPFLAGS=${CPPFLAGS} CPPFLAGS=${regular_CPPFLAGS} AC_PREPROC_IFELSE([AC_LANG_SOURCE([[ #include <netinet/if_ether.h> #if defined(__UAPI_DEF_ETHHDR) && __UAPI_DEF_ETHHDR == 0 #else #error No __UAPI_DEF_ETHHDR #endif ]])], [AC_DEFINE([__UAPI_DEF_ETHHDR], [0], [Prevent multiple definitions of `struct ethhdr`])]) CPPFLAGS=${saved_CPPFLAGS} 2. Just check `${host_os}`: AS_IF([test "${host_os}" = "linux-musl"], [AC_DEFINE([__UAPI_DEF_ETHHDR], [0], [Prevent multiple definitions of `struct ethhdr`])]) J.
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