c0bace7984
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 <linux/in6.h> is included after musl's <netinet/in.h>: ./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' The comments referencing glibc are still correct, but this file is not only used for glibc any more. Signed-off-by: Felix Janda <felix.janda@posteo.de> Reviewed-by: Hauke Mehrtens <hauke@hauke-m.de> Signed-off-by: David S. Miller <davem@davemloft.net>
268 lines
8.1 KiB
C
268 lines
8.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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/*
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* Compatibility interface for userspace libc header coordination:
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*
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* Define compatibility macros that are used to control the inclusion or
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* exclusion of UAPI structures and definitions in coordination with another
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* userspace C library.
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*
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* This header is intended to solve the problem of UAPI definitions that
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* conflict with userspace definitions. If a UAPI header has such conflicting
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* definitions then the solution is as follows:
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*
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* * Synchronize the UAPI header and the libc headers so either one can be
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* used and such that the ABI is preserved. If this is not possible then
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* no simple compatibility interface exists (you need to write translating
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* wrappers and rename things) and you can't use this interface.
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*
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* Then follow this process:
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*
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* (a) Include libc-compat.h in the UAPI header.
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* e.g. #include <linux/libc-compat.h>
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* This include must be as early as possible.
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*
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* (b) In libc-compat.h add enough code to detect that the comflicting
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* userspace libc header has been included first.
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*
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* (c) If the userspace libc header has been included first define a set of
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* guard macros of the form __UAPI_DEF_FOO and set their values to 1, else
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* set their values to 0.
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*
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* (d) Back in the UAPI header with the conflicting definitions, guard the
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* definitions with:
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* #if __UAPI_DEF_FOO
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* ...
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* #endif
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*
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* This fixes the situation where the linux headers are included *after* the
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* libc headers. To fix the problem with the inclusion in the other order the
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* userspace libc headers must be fixed like this:
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*
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* * For all definitions that conflict with kernel definitions wrap those
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* defines in the following:
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* #if !__UAPI_DEF_FOO
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* ...
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* #endif
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*
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* This prevents the redefinition of a construct already defined by the kernel.
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*/
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#ifndef _UAPI_LIBC_COMPAT_H
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#define _UAPI_LIBC_COMPAT_H
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/* We have included glibc headers... */
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#if defined(__GLIBC__)
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/* Coordinate with glibc net/if.h header. */
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#if defined(_NET_IF_H) && defined(__USE_MISC)
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/* GLIBC headers included first so don't define anything
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* that would already be defined. */
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#define __UAPI_DEF_IF_IFCONF 0
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#define __UAPI_DEF_IF_IFMAP 0
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#define __UAPI_DEF_IF_IFNAMSIZ 0
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#define __UAPI_DEF_IF_IFREQ 0
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/* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
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#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 0
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/* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
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#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO
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#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
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#endif /* __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO */
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#else /* _NET_IF_H */
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/* Linux headers included first, and we must define everything
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* we need. The expectation is that glibc will check the
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* __UAPI_DEF_* defines and adjust appropriately. */
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#define __UAPI_DEF_IF_IFCONF 1
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#define __UAPI_DEF_IF_IFMAP 1
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#define __UAPI_DEF_IF_IFNAMSIZ 1
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#define __UAPI_DEF_IF_IFREQ 1
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/* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
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#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 1
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/* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
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#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
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#endif /* _NET_IF_H */
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/* Coordinate with glibc netinet/in.h header. */
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#if defined(_NETINET_IN_H)
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/* GLIBC headers included first so don't define anything
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* that would already be defined. */
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#define __UAPI_DEF_IN_ADDR 0
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#define __UAPI_DEF_IN_IPPROTO 0
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#define __UAPI_DEF_IN_PKTINFO 0
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#define __UAPI_DEF_IP_MREQ 0
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#define __UAPI_DEF_SOCKADDR_IN 0
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#define __UAPI_DEF_IN_CLASS 0
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#define __UAPI_DEF_IN6_ADDR 0
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/* The exception is the in6_addr macros which must be defined
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* if the glibc code didn't define them. This guard matches
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* the guard in glibc/inet/netinet/in.h which defines the
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* additional in6_addr macros e.g. s6_addr16, and s6_addr32. */
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#if defined(__USE_MISC) || defined (__USE_GNU)
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#define __UAPI_DEF_IN6_ADDR_ALT 0
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#else
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#define __UAPI_DEF_IN6_ADDR_ALT 1
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#endif
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#define __UAPI_DEF_SOCKADDR_IN6 0
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#define __UAPI_DEF_IPV6_MREQ 0
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#define __UAPI_DEF_IPPROTO_V6 0
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#define __UAPI_DEF_IPV6_OPTIONS 0
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#define __UAPI_DEF_IN6_PKTINFO 0
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#define __UAPI_DEF_IP6_MTUINFO 0
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#else
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/* Linux headers included first, and we must define everything
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* we need. The expectation is that glibc will check the
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* __UAPI_DEF_* defines and adjust appropriately. */
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#define __UAPI_DEF_IN_ADDR 1
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#define __UAPI_DEF_IN_IPPROTO 1
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#define __UAPI_DEF_IN_PKTINFO 1
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#define __UAPI_DEF_IP_MREQ 1
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#define __UAPI_DEF_SOCKADDR_IN 1
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#define __UAPI_DEF_IN_CLASS 1
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#define __UAPI_DEF_IN6_ADDR 1
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/* We unconditionally define the in6_addr macros and glibc must
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* coordinate. */
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#define __UAPI_DEF_IN6_ADDR_ALT 1
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#define __UAPI_DEF_SOCKADDR_IN6 1
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#define __UAPI_DEF_IPV6_MREQ 1
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#define __UAPI_DEF_IPPROTO_V6 1
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#define __UAPI_DEF_IPV6_OPTIONS 1
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#define __UAPI_DEF_IN6_PKTINFO 1
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#define __UAPI_DEF_IP6_MTUINFO 1
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#endif /* _NETINET_IN_H */
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/* Coordinate with glibc netipx/ipx.h header. */
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#if defined(__NETIPX_IPX_H)
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#define __UAPI_DEF_SOCKADDR_IPX 0
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#define __UAPI_DEF_IPX_ROUTE_DEFINITION 0
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#define __UAPI_DEF_IPX_INTERFACE_DEFINITION 0
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#define __UAPI_DEF_IPX_CONFIG_DATA 0
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#define __UAPI_DEF_IPX_ROUTE_DEF 0
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#else /* defined(__NETIPX_IPX_H) */
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#define __UAPI_DEF_SOCKADDR_IPX 1
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#define __UAPI_DEF_IPX_ROUTE_DEFINITION 1
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#define __UAPI_DEF_IPX_INTERFACE_DEFINITION 1
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#define __UAPI_DEF_IPX_CONFIG_DATA 1
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#define __UAPI_DEF_IPX_ROUTE_DEF 1
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#endif /* defined(__NETIPX_IPX_H) */
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/* Definitions for xattr.h */
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#if defined(_SYS_XATTR_H)
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#define __UAPI_DEF_XATTR 0
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#else
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#define __UAPI_DEF_XATTR 1
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#endif
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/* If we did not see any headers from any supported C libraries,
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* or we are being included in the kernel, then define everything
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* that we need. Check for previous __UAPI_* definitions to give
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* unsupported C libraries a way to opt out of any kernel definition. */
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#else /* !defined(__GLIBC__) */
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/* Definitions for if.h */
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#ifndef __UAPI_DEF_IF_IFCONF
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#define __UAPI_DEF_IF_IFCONF 1
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#endif
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#ifndef __UAPI_DEF_IF_IFMAP
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#define __UAPI_DEF_IF_IFMAP 1
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#endif
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#ifndef __UAPI_DEF_IF_IFNAMSIZ
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#define __UAPI_DEF_IF_IFNAMSIZ 1
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#endif
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#ifndef __UAPI_DEF_IF_IFREQ
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#define __UAPI_DEF_IF_IFREQ 1
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#endif
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/* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
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#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS
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#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 1
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#endif
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/* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
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#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO
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#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
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#endif
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/* Definitions for in.h */
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#ifndef __UAPI_DEF_IN_ADDR
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#define __UAPI_DEF_IN_ADDR 1
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#endif
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#ifndef __UAPI_DEF_IN_IPPROTO
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#define __UAPI_DEF_IN_IPPROTO 1
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#endif
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#ifndef __UAPI_DEF_IN_PKTINFO
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#define __UAPI_DEF_IN_PKTINFO 1
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#endif
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#ifndef __UAPI_DEF_IP_MREQ
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#define __UAPI_DEF_IP_MREQ 1
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#endif
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#ifndef __UAPI_DEF_SOCKADDR_IN
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#define __UAPI_DEF_SOCKADDR_IN 1
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#endif
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#ifndef __UAPI_DEF_IN_CLASS
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#define __UAPI_DEF_IN_CLASS 1
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#endif
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/* Definitions for in6.h */
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#ifndef __UAPI_DEF_IN6_ADDR
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#define __UAPI_DEF_IN6_ADDR 1
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#endif
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#ifndef __UAPI_DEF_IN6_ADDR_ALT
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#define __UAPI_DEF_IN6_ADDR_ALT 1
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#endif
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#ifndef __UAPI_DEF_SOCKADDR_IN6
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#define __UAPI_DEF_SOCKADDR_IN6 1
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#endif
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#ifndef __UAPI_DEF_IPV6_MREQ
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#define __UAPI_DEF_IPV6_MREQ 1
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#endif
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#ifndef __UAPI_DEF_IPPROTO_V6
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#define __UAPI_DEF_IPPROTO_V6 1
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#endif
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#ifndef __UAPI_DEF_IPV6_OPTIONS
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#define __UAPI_DEF_IPV6_OPTIONS 1
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#endif
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#ifndef __UAPI_DEF_IN6_PKTINFO
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#define __UAPI_DEF_IN6_PKTINFO 1
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#endif
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#ifndef __UAPI_DEF_IP6_MTUINFO
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#define __UAPI_DEF_IP6_MTUINFO 1
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#endif
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/* Definitions for ipx.h */
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#ifndef __UAPI_DEF_SOCKADDR_IPX
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#define __UAPI_DEF_SOCKADDR_IPX 1
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#endif
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#ifndef __UAPI_DEF_IPX_ROUTE_DEFINITION
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#define __UAPI_DEF_IPX_ROUTE_DEFINITION 1
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#endif
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#ifndef __UAPI_DEF_IPX_INTERFACE_DEFINITION
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#define __UAPI_DEF_IPX_INTERFACE_DEFINITION 1
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#endif
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#ifndef __UAPI_DEF_IPX_CONFIG_DATA
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#define __UAPI_DEF_IPX_CONFIG_DATA 1
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#endif
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#ifndef __UAPI_DEF_IPX_ROUTE_DEF
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#define __UAPI_DEF_IPX_ROUTE_DEF 1
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#endif
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/* Definitions for xattr.h */
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#ifndef __UAPI_DEF_XATTR
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#define __UAPI_DEF_XATTR 1
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#endif
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#endif /* __GLIBC__ */
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#endif /* _UAPI_LIBC_COMPAT_H */
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