target/linux/generic/pending-3.18/270-uapi-libc-compat-add-fallback-for-unsupported-libcs.patch

   1 From c6bdd0d302119819de72439972d0462c26ef9eda Mon Sep 17 00:00:00 2001
   2 From: Felix Janda <felix.janda@posteo.de>
   3 Date: Sun, 12 Nov 2017 13:30:17 -0500
   4 Subject: uapi libc compat: add fallback for unsupported libcs
   5
   6 libc-compat.h aims to prevent symbol collisions between uapi and libc
   7 headers for each supported libc. This requires continuous coordination
   8 between them.
   9
  10 The goal of this commit is to improve the situation for libcs (such as
  11 musl) which are not yet supported and/or do not wish to be explicitly
  12 supported, while not affecting supported libcs. More precisely, with
  13 this commit, unsupported libcs can request the suppression of any
  14 specific uapi definition by defining the correspondings _UAPI_DEF_*
  15 macro as 0. This can fix symbol collisions for them, as long as the
  16 libc headers are included before the uapi headers. Inclusion in the
  17 other order is outside the scope of this commit.
  18
  19 All infrastructure in order to enable this fallback for unsupported
  20 libcs is already in place, except that libc-compat.h unconditionally
  21 defines all _UAPI_DEF_* macros to 1 for all unsupported libcs so that
  22 any previous definitions are ignored. In order to fix this, this commit
  23 merely makes these definitions conditional.
  24
  25 This commit together with the musl libc commit
  26
  27 http://git.musl-libc.org/cgit/musl/commit/?id=04983f2272382af92eb8f8838964ff944fbb8258
  28
  29 fixes for example the following compiler errors when <linux/in6.h> is
  30 included after musl's <netinet/in.h>:
  31
  32 ./linux/in6.h:32:8: error: redefinition of 'struct in6_addr'
  33 ./linux/in6.h:49:8: error: redefinition of 'struct sockaddr_in6'
  34 ./linux/in6.h:59:8: error: redefinition of 'struct ipv6_mreq'
  35
  36 The comments referencing glibc are still correct, but this file is not
  37 only used for glibc any more.
  38
  39 Signed-off-by: Felix Janda <felix.janda@posteo.de>
  40 Reviewed-by: Hauke Mehrtens <hauke@hauke-m.de>
  41 ---
  42  include/uapi/linux/libc-compat.h | 55 +++++++++++++++++++++++++++++++++++++++-
  43  1 file changed, 54 insertions(+), 1 deletion(-)
  44
  45 --- a/include/uapi/linux/libc-compat.h
  46 +++ b/include/uapi/linux/libc-compat.h
  47 @@ -110,27 +110,54 @@
  48
  49  /* If we did not see any headers from any supported C libraries,
  50   * or we are being included in the kernel, then define everything
  51 - * that we need. */
  52 + * that we need. Check for previous __UAPI_* definitions to give
  53 + * unsupported C libraries a way to opt out of any kernel definition. */
  54  #else /* !defined(__GLIBC__) */
  55
  56  /* Definitions for in.h */
  57 +#ifndef __UAPI_DEF_IN_ADDR
  58  #define __UAPI_DEF_IN_ADDR             1
  59 +#endif
  60 +#ifndef __UAPI_DEF_IN_IPPROTO
  61  #define __UAPI_DEF_IN_IPPROTO          1
  62 +#endif
  63 +#ifndef __UAPI_DEF_IN_PKTINFO
  64  #define __UAPI_DEF_IN_PKTINFO          1
  65 +#endif
  66 +#ifndef __UAPI_DEF_IP_MREQ
  67  #define __UAPI_DEF_IP_MREQ             1
  68 +#endif
  69 +#ifndef __UAPI_DEF_SOCKADDR_IN
  70  #define __UAPI_DEF_SOCKADDR_IN         1
  71 +#endif
  72 +#ifndef __UAPI_DEF_IN_CLASS
  73  #define __UAPI_DEF_IN_CLASS            1
  74 +#endif
  75
  76  /* Definitions for in6.h */
  77 +#ifndef __UAPI_DEF_IN6_ADDR
  78  #define __UAPI_DEF_IN6_ADDR            1
  79 +#endif
  80 +#ifndef __UAPI_DEF_IN6_ADDR_ALT
  81  #define __UAPI_DEF_IN6_ADDR_ALT                1
  82 +#endif
  83 +#ifndef __UAPI_DEF_SOCKADDR_IN6
  84  #define __UAPI_DEF_SOCKADDR_IN6                1
  85 +#endif
  86 +#ifndef __UAPI_DEF_IPV6_MREQ
  87  #define __UAPI_DEF_IPV6_MREQ           1
  88 +#endif
  89 +#ifndef __UAPI_DEF_IPPROTO_V6
  90  #define __UAPI_DEF_IPPROTO_V6          1
  91 +#endif
  92 +#ifndef __UAPI_DEF_IPV6_OPTIONS
  93  #define __UAPI_DEF_IPV6_OPTIONS                1
  94 +#endif
  95
  96  /* Definitions for xattr.h */
  97 +#ifndef __UAPI_DEF_XATTR
  98  #define __UAPI_DEF_XATTR               1
  99 +#endif
 100
 101  #endif /* __GLIBC__ */
 102