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

   1 // -*- C++ -*- Helpers for calling unextected and terminate
   2 // Copyright (C) 2001-2023 Free Software Foundation, Inc.
   3 //
   4 // This file is part of GCC.
   5 //
   6 // GCC is free software; you can redistribute it and/or modify
   7 // it under the terms of the GNU General Public License as published by
   8 // the Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10 //
  11 // GCC is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15 //
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 #include <bits/c++config.h>
  26 #include <cstdlib>
  27 #include <bits/exception_defines.h>
  28 #include "unwind-cxx.h"
  29
  30 using namespace __cxxabiv1;
  31
  32 #include "unwind-pe.h"
  33
  34
  35 // Helper routine for when the exception handling code needs to call
  36 // terminate.
  37
  38 extern "C" void
  39 __cxa_call_terminate(void* ue_header_in) throw ()
  40 {
  41   _Unwind_Exception* ue_header
  42     = reinterpret_cast<_Unwind_Exception*>(ue_header_in);
  43
  44   if (ue_header)
  45     {
  46       // terminate is classed as a catch handler.
  47       __cxa_begin_catch(ue_header);
  48
  49       // Call the terminate handler that was in effect when we threw this
  50       // exception.  */
  51       if (__is_gxx_exception_class(ue_header->exception_class))
  52         {
  53           __cxa_exception* xh;
  54
  55           xh = __get_exception_header_from_ue(ue_header);
  56           __terminate(xh->terminateHandler);
  57         }
  58     }
  59   /* Call the global routine if we don't have anything better.  */
  60   std::terminate();
  61 }
  62
  63
  64 #ifdef __ARM_EABI_UNWINDER__
  65 // The ARM EABI __cxa_call_unexpected has the same semantics as the generic
  66 // routine, but the exception specification has a different format.
  67 extern "C" void
  68 __cxa_call_unexpected(void* exc_obj_in)
  69 {
  70   _Unwind_Exception* exc_obj
  71     = reinterpret_cast<_Unwind_Exception*>(exc_obj_in);
  72
  73   int rtti_count = 0;
  74   _Unwind_Word rtti_stride = 0;
  75   _Unwind_Word* rtti_list = NULL;
  76   _Unwind_Ptr rtti_base = 0;
  77   bool foreign_exception;
  78   std::unexpected_handler unexpectedHandler = NULL;
  79   std::terminate_handler terminateHandler = NULL;
  80   __cxa_exception* xh;
  81   if (__is_gxx_exception_class(exc_obj->exception_class))
  82     {
  83       // Save data from the EO, which may be clobbered by _cxa_begin_catch.
  84       xh = __get_exception_header_from_ue(exc_obj);
  85       unexpectedHandler = xh->unexpectedHandler;
  86       terminateHandler = xh->terminateHandler;
  87       rtti_count = exc_obj->barrier_cache.bitpattern[1];
  88       rtti_base = (_Unwind_Ptr) exc_obj->barrier_cache.bitpattern[2];
  89       rtti_stride = exc_obj->barrier_cache.bitpattern[3];
  90       rtti_list = (_Unwind_Word*) exc_obj->barrier_cache.bitpattern[4];
  91       foreign_exception = false;
  92     }
  93   else
  94     foreign_exception = true;
  95
  96   /* This must be called after extracting data from the EO, but before
  97      calling unexpected().   */
  98   __cxa_begin_catch(exc_obj);
  99
 100   // This function is a handler for our exception argument.  If we exit
 101   // by throwing a different exception, we'll need the original cleaned up.
 102   struct end_catch_protect
 103   {
 104     end_catch_protect() { }
 105     ~end_catch_protect() { __cxa_end_catch(); }
 106   } end_catch_protect_obj;
 107
 108
 109   __try
 110     {
 111       if (foreign_exception)
 112         std::unexpected();
 113       else
 114         __unexpected(unexpectedHandler);
 115     }
 116   __catch(...)
 117     {
 118       /* See if the new exception matches the rtti list.  */
 119       if (foreign_exception)
 120         std::terminate();
 121
 122       // Get the exception thrown from unexpected.
 123
 124       __cxa_eh_globals* globals = __cxa_get_globals_fast();
 125       __cxa_exception* new_xh = globals->caughtExceptions;
 126       void* new_ptr = __get_object_from_ambiguous_exception (new_xh);
 127       const std::type_info* catch_type;
 128       int n;
 129       bool bad_exception_allowed __attribute__((unused)) = false;
 130       const std::type_info& bad_exc = typeid(std::bad_exception);
 131
 132       // Check the new exception against the rtti list
 133       for (n = 0; n < rtti_count; n++)
 134         {
 135           _Unwind_Word offset;
 136
 137           offset = (_Unwind_Word) &rtti_list[n * (rtti_stride >> 2)];
 138           offset = _Unwind_decode_typeinfo_ptr(rtti_base, offset);
 139           catch_type = (const std::type_info*) (offset);
 140
 141           if (__cxa_type_match(&new_xh->unwindHeader, catch_type, false,
 142                                &new_ptr) != ctm_failed)
 143             { __throw_exception_again; }
 144
 145           // If the exception spec allows std::bad_exception, throw that.
 146           // We don't have a thrown object to compare against, but since
 147           // bad_exception doesn't have virtual bases, that's OK; just pass NULL.
 148           void* obj = NULL;
 149           if (catch_type->__do_catch(&bad_exc, &obj, 1))
 150             bad_exception_allowed = true;
 151         }
 152
 153       // If the exception spec allows std::bad_exception, throw that.
 154 #if __cpp_exceptions
 155       if (bad_exception_allowed)
 156         throw std::bad_exception();
 157 #endif
 158
 159       // Otherwise, die.
 160       __terminate(terminateHandler);
 161     }
 162 }
 163 #endif // __ARM_EABI_UNWINDER__