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![Hauke Mehrtens](/assets/img/avatar_default.png)
This fixes a compile problem of some user space applications by not
including linux/libc-compat.h in uapi/if_ether.h.
linux/libc-compat.h checks which "features" the header files, included
from the libc, provide to make the Linux kernel uapi header files only
provide no conflicting structures and enums. If a user application mixes
kernel headers and libc headers it could happen that linux/libc-compat.h
gets included too early where not all other libc headers are included
yet. Then the linux/libc-compat.h would not prevent all the
redefinitions and we run into compile problems.
This patch removes the include of linux/libc-compat.h from
uapi/if_ether.h to fix the recently introduced case, but not all as this
is more or less impossible.
It is no problem to do the check directly in the if_ether.h file and not
in libc-compat.h as this does not need any fancy glibc header detection
as glibc never provided struct ethhdr and should define
__UAPI_DEF_ETHHDR by them self when they will provide this.
The following test program did not compile correctly any more:
#include <linux/if_ether.h>
#include <netinet/in.h>
#include <linux/in.h>
int main(void)
{
return 0;
}
Fixes: 6926e041a8
("uapi/if_ether.h: prevent redefinition of struct ethhdr")
Reported-by: Guillaume Nault <g.nault@alphalink.fr>
Cc: <stable@vger.kernel.org> # 4.15
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
267 lines
8.1 KiB
C
267 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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