libstdc++-v3/libsupc++/vtv_stubs.cc

   1 // Copyright (C) 2012-2014 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // Under Section 7 of GPL version 3, you are granted additional
  15 // permissions described in the GCC Runtime Library Exception, version
  16 // 3.1, as published by the Free Software Foundation.
  17
  18 // You should have received a copy of the GNU General Public License and
  19 // a copy of the GCC Runtime Library Exception along with this program;
  20 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  21 // <http://www.gnu.org/licenses/>.
  22
  23 /* This is part of the vtable verification runtime library.  For more
  24    information about this feature, see the comments in libvtv/vtv_rts.cc.  */
  25
  26 /* The functions in this file are used to create the libvtv_stubs
  27    library, as part of the vtable verification feature.  When building
  28    a binary without vtable verification, and linking it with a
  29    (possibly pre-built third-party) library that was built with
  30    verification, it is possible that vtable verification will fail due
  31    to incomplete data (rather than due to corrupt vtable pointers).  In
  32    this case we need to give programmers a way of turning off the
  33    vtable verification in their libraries.  They can do so by linking
  34    with the libvtv_stubs library, which (as you can see) will replace
  35    the real verification functions with a set of functions that do
  36    nothing (so no more verification failures/aborts).  */
  37
  38 #include <cstddef>
  39
  40 // Declare as weak for libsupc++, strong definitions are in libvtv.
  41 #if __GXX_WEAK__
  42 extern "C"
  43 void
  44 __VLTChangePermission(int) __attribute__((weak));
  45
  46 void
  47 __VLTRegisterSet(void**, const void*, std::size_t, std::size_t,
  48                  void**) __attribute__((weak));
  49
  50 void
  51 __VLTRegisterPair(void**, const void*, std::size_t,
  52                   const void*) __attribute__((weak));
  53
  54 const void*
  55 __VLTVerifyVtablePointer(void**, const void*) __attribute__((weak));
  56
  57 void
  58 __VLTRegisterSetDebug(void**, const void*, std::size_t, std::size_t,
  59                       void**) __attribute__((weak));
  60
  61 void
  62 __VLTRegisterPairDebug(void**, const void*, std::size_t, const void*,
  63                        const char*, const char*) __attribute__((weak));
  64
  65 const void*
  66 __VLTVerifyVtablePointerDebug(void**, const void*, const char*,
  67                               const char*) __attribute__((weak));
  68 #endif
  69
  70 // Stub definitions.
  71 extern "C"
  72 void
  73 __VLTChangePermission(int)
  74 { }
  75
  76 void
  77 __VLTRegisterSet(void**, const void*, std::size_t, std::size_t, void**)
  78 { }
  79
  80 void
  81 __VLTRegisterPair(void**, const void*, std::size_t, const void*)
  82 { }
  83
  84 const void*
  85 __VLTVerifyVtablePointer(void**, const void* vtable_ptr)
  86 { return vtable_ptr; }
  87
  88 void
  89 __VLTRegisterSetDebug(void**, const void*, std::size_t, std::size_t, void**)
  90 { }
  91
  92 void
  93 __VLTRegisterPairDebug(void**, const void*, std::size_t, const void*,
  94                        const char*, const  char*)
  95 { }
  96
  97 const void*
  98 __VLTVerifyVtablePointerDebug(void**, const void* vtable_ptr, const char*,
  99                               const char*)
 100 { return vtable_ptr; }