Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751997AbdGHVpw (ORCPT ); Sat, 8 Jul 2017 17:45:52 -0400 Received: from mout02.posteo.de ([185.67.36.66]:47130 "EHLO mout02.posteo.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750929AbdGHVpu (ORCPT ); Sat, 8 Jul 2017 17:45:50 -0400 Date: Sat, 8 Jul 2017 17:44:02 -0400 From: Felix Janda To: musl@lists.openwall.com Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, "David S. Miller" , "Carlos O'Donell" Subject: Re: [musl] [PATCHv2] uapi libc compat: add fallback for unsupported libcs Message-ID: <20170708214402.GA2742@nyan> Mail-Followup-To: musl@lists.openwall.com, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, "David S. Miller" , Carlos O'Donell References: <20170708202732.GA1891@nyan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5800 Lines: 170 Hauke Mehrtens wrote: > > > On 07/08/2017 10:27 PM, Felix Janda wrote: > > libc-compat.h aims to prevent symbol collisions between uapi and libc > > headers for each supported libc. This requires continuous coordination > > between them. > > > > The goal of this commit is to improve the situation for libcs (such as > > musl) which are not yet supported and/or do not wish to be explicitly > > supported, while not affecting supported libcs. More precisely, with > > this commit, unsupported libcs can request the suppression of any > > specific uapi definition by defining the correspondings _UAPI_DEF_* > > macro as 0. This can fix symbol collisions for them, as long as the > > libc headers are included before the uapi headers. Inclusion in the > > other order is outside the scope of this commit. > > > > All infrastructure in order to enable this fallback for unsupported > > libcs is already in place, except that libc-compat.h unconditionally > > defines all _UAPI_DEF_* macros to 1 for all unsupported libcs so that > > any previous definitions are ignored. In order to fix this, this commit > > merely makes these definitions conditional. > > > > This commit together with the musl libc commit > > > > http://git.musl-libc.org/cgit/musl/commit/?id=04983f2272382af92eb8f8838964ff944fbb8258 > > > > fixes for example the following compiler errors when is > > included after musl's : > > > > ./linux/in6.h:32:8: error: redefinition of 'struct in6_addr' > > ./linux/in6.h:49:8: error: redefinition of 'struct sockaddr_in6' > > ./linux/in6.h:59:8: error: redefinition of 'struct ipv6_mreq' > > > > Signed-off-by: Felix Janda > > Acked-by: Rich Felker > > --- > > v2: The only change to the previous version is the commit title and > > message. > > --- > > include/uapi/linux/libc-compat.h | 52 ++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 52 insertions(+) > > Does the documentation at the top of this file need some updates? I think that at least the comment preceding the part touched by this patch should be updated. I'm not sure how to update the documentation on top -- it does not say anything about unsupported libcs. > > diff --git a/include/uapi/linux/libc-compat.h b/include/uapi/linux/libc-compat.h > > index 44b8a6b..c316725 100644 > > --- a/include/uapi/linux/libc-compat.h > > +++ b/include/uapi/linux/libc-compat.h > > @@ -171,42 +171,94 @@ > > #else /* !defined(__GLIBC__) */ > > Why don't you used #ifndef ? It seemed more consistent with the rest of the file, which also uses "#if defined(...)" instead of "#ifdef". On the other hand, there are two uses of "#ifndef" in the file. I do not have any strong opinion on this. > > /* Definitions for if.h */ > > +#if !defined(__UAPI_DEF_IF_IFCONF) > > #define __UAPI_DEF_IF_IFCONF 1 > > +#endif > > +#if !defined(__UAPI_DEF_IF_IFMAP) > > #define __UAPI_DEF_IF_IFMAP 1 > > +#endif > > +#if !defined(__UAPI_DEF_IFNAMSIZ) > > This should be: > #if !defined( __UAPI_DEF_IF_IFNAMSIZ) > > > #define __UAPI_DEF_IF_IFNAMSIZ 1 > > +#endif > > +#if !defined(__UAPI_DEF_IFREQ) > > This should be: > #if !defined(__UAPI_DEF_IF_IFREQ) Thanks! Will be fixed in the next version. Felix > > #define __UAPI_DEF_IF_IFREQ 1 > > +#endif > > /* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */ > > +#if !defined(__UAPI_DEF_IF_NET_DEVICE_FLAGS) > > #define __UAPI_DEF_IF_NET_DEVICE_FLAGS 1 > > +#endif > > /* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */ > > +#if !defined(__UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO) > > #define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1 > > +#endif > > > > /* Definitions for in.h */ > > +#if !defined(__UAPI_DEF_IN_ADDR) > > #define __UAPI_DEF_IN_ADDR 1 > > +#endif > > +#if !defined(__UAPI_DEF_IN_IPPROTO) > > #define __UAPI_DEF_IN_IPPROTO 1 > > +#endif > > +#if !defined(__UAPI_DEF_IN_PKTINFO) > > #define __UAPI_DEF_IN_PKTINFO 1 > > +#endif > > +#if !defined(__UAPI_DEF_IP_MREQ) > > #define __UAPI_DEF_IP_MREQ 1 > > +#endif > > +#if !defined(__UAPI_DEF_SOCKADDR_IN) > > #define __UAPI_DEF_SOCKADDR_IN 1 > > +#endif > > +#if !defined(__UAPI_DEF_IN_CLASS) > > #define __UAPI_DEF_IN_CLASS 1 > > +#endif > > > > /* Definitions for in6.h */ > > +#if !defined(__UAPI_DEF_IN6_ADDR) > > #define __UAPI_DEF_IN6_ADDR 1 > > +#endif > > +#if !defined(__UAPI_DEF_IN6_ADDR_ALT) > > #define __UAPI_DEF_IN6_ADDR_ALT 1 > > +#endif > > +#if !defined(__UAPI_DEF_SOCKADDR_IN6) > > #define __UAPI_DEF_SOCKADDR_IN6 1 > > +#endif > > +#if !defined(__UAPI_DEF_IPV6_MREQ) > > #define __UAPI_DEF_IPV6_MREQ 1 > > +#endif > > +#if !defined(__UAPI_DEF_IPPROTO_V6) > > #define __UAPI_DEF_IPPROTO_V6 1 > > +#endif > > +#if !defined(__UAPI_DEF_IPV6_OPTIONS) > > #define __UAPI_DEF_IPV6_OPTIONS 1 > > +#endif > > +#if !defined(__UAPI_DEF_IN6_PKTINFO) > > #define __UAPI_DEF_IN6_PKTINFO 1 > > +#endif > > +#if !defined(__UAPI_DEF_IP6_MTUINFO) > > #define __UAPI_DEF_IP6_MTUINFO 1 > > +#endif > > > > /* Definitions for ipx.h */ > > +#if !defined(__UAPI_DEF_SOCKADDR_IPX) > > #define __UAPI_DEF_SOCKADDR_IPX 1 > > +#endif > > +#if !defined(__UAPI_DEF_IPX_ROUTE_DEFINITION) > > #define __UAPI_DEF_IPX_ROUTE_DEFINITION 1 > > +#endif > > +#if !defined(__UAPI_DEF_IPX_INTERFACE_DEFINITION) > > #define __UAPI_DEF_IPX_INTERFACE_DEFINITION 1 > > +#endif > > +#if !defined(__UAPI_DEF_IPX_CONFIG_DATA) > > #define __UAPI_DEF_IPX_CONFIG_DATA 1 > > +#endif > > +#if !defined(__UAPI_DEF_IPX_ROUTE_DEF) > > #define __UAPI_DEF_IPX_ROUTE_DEF 1 > > +#endif > > > > /* Definitions for xattr.h */ > > +#if !defined(__UAPI_DEF_XATTR) > > #define __UAPI_DEF_XATTR 1 > > +#endif > > > > #endif /* __GLIBC__ */ > > > > --