Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751915AbdGHVOi (ORCPT ); Sat, 8 Jul 2017 17:14:38 -0400 Received: from hauke-m.de ([5.39.93.123]:55907 "EHLO mail.hauke-m.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750910AbdGHVOh (ORCPT ); Sat, 8 Jul 2017 17:14:37 -0400 Subject: Re: [musl] [PATCHv2] uapi libc compat: add fallback for unsupported libcs To: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, musl@lists.openwall.com, "David S. Miller" , "Carlos O'Donell" References: <20170708202732.GA1891@nyan> From: Hauke Mehrtens Message-ID: Date: Sat, 8 Jul 2017 23:14:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170708202732.GA1891@nyan> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5004 Lines: 154 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? > 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 ? > /* 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) > #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__ */ > >