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

   1 // -*- C++ -*- Implement the members of exception_ptr.
   2 // Copyright (C) 2008-2024 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 "eh_atomics.h"
  27
  28 // This macro causes exception_ptr to declare an older API (with corresponding
  29 // definitions in this file).
  30 #define _GLIBCXX_EH_PTR_COMPAT
  31
  32 #if ! _GLIBCXX_INLINE_VERSION
  33 // This macro causes some inline functions in exception_ptr to be marked
  34 // as "used" so that definitions will be emitted in this translation unit.
  35 // We need this because those functions were not inline in previous releases.
  36 #define _GLIBCXX_EH_PTR_RELOPS_COMPAT
  37 #endif
  38
  39 #include <exception>
  40 #include <bits/exception_ptr.h>
  41 #include "unwind-cxx.h"
  42
  43 using namespace __cxxabiv1;
  44
  45 // Verify assumptions about member layout in exception types
  46 namespace
  47 {
  48 template<typename Ex>
  49   constexpr std::size_t unwindhdr()
  50   { return offsetof(Ex, unwindHeader); }
  51
  52 template<typename Ex>
  53   constexpr std::size_t termHandler()
  54   { return unwindhdr<Ex>() - offsetof(Ex, terminateHandler); }
  55
  56 static_assert( termHandler<__cxa_exception>()
  57                == termHandler<__cxa_dependent_exception>(),
  58                "__cxa_dependent_exception::termHandler layout must be"
  59                " consistent with __cxa_exception::termHandler" );
  60
  61 #ifndef __ARM_EABI_UNWINDER__
  62 template<typename Ex>
  63   constexpr std::ptrdiff_t adjptr()
  64   { return unwindhdr<Ex>() - offsetof(Ex, adjustedPtr); }
  65
  66 static_assert( adjptr<__cxa_exception>()
  67                == adjptr<__cxa_dependent_exception>(),
  68                "__cxa_dependent_exception::adjustedPtr layout must be"
  69                " consistent with __cxa_exception::adjustedPtr" );
  70 #endif
  71 }
  72
  73 // Define non-inline functions.
  74
  75 std::__exception_ptr::exception_ptr::exception_ptr(void* obj) noexcept
  76 : _M_exception_object(obj)  { _M_addref(); }
  77
  78
  79 std::__exception_ptr::exception_ptr::exception_ptr(__safe_bool) noexcept
  80 : _M_exception_object(nullptr) { }
  81
  82
  83 void
  84 std::__exception_ptr::exception_ptr::_M_addref() noexcept
  85 {
  86   if (__builtin_expect(_M_exception_object != nullptr, true))
  87     {
  88       __cxa_refcounted_exception *eh =
  89         __get_refcounted_exception_header_from_obj (_M_exception_object);
  90       __gnu_cxx::__eh_atomic_inc (&eh->referenceCount);
  91     }
  92 }
  93
  94
  95 void
  96 std::__exception_ptr::exception_ptr::_M_release() noexcept
  97 {
  98   if (__builtin_expect(_M_exception_object != nullptr, true))
  99     {
 100       __cxa_refcounted_exception *eh =
 101         __get_refcounted_exception_header_from_obj (_M_exception_object);
 102       if (__gnu_cxx::__eh_atomic_dec (&eh->referenceCount))
 103         {
 104           if (eh->exc.exceptionDestructor)
 105             eh->exc.exceptionDestructor (_M_exception_object);
 106
 107           __cxa_free_exception (_M_exception_object);
 108           _M_exception_object = nullptr;
 109         }
 110     }
 111 }
 112
 113
 114 void*
 115 std::__exception_ptr::exception_ptr::_M_get() const noexcept
 116 { return _M_exception_object; }
 117
 118
 119
 120 // Retained for compatibility with CXXABI_1.3.
 121 void
 122 std::__exception_ptr::exception_ptr::_M_safe_bool_dummy() noexcept { }
 123
 124
 125 // Retained for compatibility with CXXABI_1.3.
 126 bool
 127 std::__exception_ptr::exception_ptr::operator!() const noexcept
 128 { return _M_exception_object == nullptr; }
 129
 130
 131 // Retained for compatibility with CXXABI_1.3.
 132 std::__exception_ptr::exception_ptr::operator __safe_bool() const noexcept
 133 {
 134   return _M_exception_object ? &exception_ptr::_M_safe_bool_dummy : nullptr;
 135 }
 136
 137 const std::type_info*
 138 std::__exception_ptr::exception_ptr::__cxa_exception_type() const noexcept
 139 {
 140   __cxa_exception *eh = __get_exception_header_from_obj (_M_exception_object);
 141   return eh->exceptionType;
 142 }
 143
 144 std::exception_ptr
 145 std::current_exception() noexcept
 146 {
 147   __cxa_eh_globals *globals = __cxa_get_globals ();
 148   __cxa_exception *header = globals->caughtExceptions;
 149
 150   if (!header)
 151     return std::exception_ptr();
 152
 153   // Since foreign exceptions can't be counted, we can't return them.
 154   if (!__is_gxx_exception_class (header->unwindHeader.exception_class))
 155     return std::exception_ptr();
 156
 157   return std::exception_ptr(
 158     __get_object_from_ambiguous_exception (header));
 159 }
 160
 161
 162 static void
 163 __gxx_dependent_exception_cleanup(_Unwind_Reason_Code code,
 164                                   _Unwind_Exception *exc)
 165 {
 166   // This cleanup is set only for dependents.
 167   __cxa_dependent_exception *dep = __get_dependent_exception_from_ue (exc);
 168   __cxa_refcounted_exception *header =
 169     __get_refcounted_exception_header_from_obj (dep->primaryException);
 170
 171   // We only want to be called through _Unwind_DeleteException.
 172   // _Unwind_DeleteException in the HP-UX IA64 libunwind library
 173   // returns _URC_NO_REASON and not _URC_FOREIGN_EXCEPTION_CAUGHT
 174   // like the GCC _Unwind_DeleteException function does.
 175   if (code != _URC_FOREIGN_EXCEPTION_CAUGHT && code != _URC_NO_REASON)
 176     __terminate (header->exc.terminateHandler);
 177
 178   __cxa_free_dependent_exception (dep);
 179
 180   if (__gnu_cxx::__eh_atomic_dec (&header->referenceCount))
 181     {
 182       if (header->exc.exceptionDestructor)
 183         header->exc.exceptionDestructor (header + 1);
 184
 185       __cxa_free_exception (header + 1);
 186     }
 187 }
 188
 189
 190 void
 191 std::rethrow_exception(std::exception_ptr ep)
 192 {
 193   void *obj = ep._M_get();
 194   __cxa_refcounted_exception *eh
 195     = __get_refcounted_exception_header_from_obj (obj);
 196
 197   __cxa_dependent_exception *dep = __cxa_allocate_dependent_exception ();
 198   dep->primaryException = obj;
 199   __gnu_cxx::__eh_atomic_inc (&eh->referenceCount);
 200
 201 #pragma GCC diagnostic push
 202 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 203   dep->unexpectedHandler = get_unexpected ();
 204 #pragma GCC diagnostic pop
 205   dep->terminateHandler = get_terminate ();
 206   __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(dep->unwindHeader.exception_class);
 207   dep->unwindHeader.exception_cleanup = __gxx_dependent_exception_cleanup;
 208
 209   __cxa_eh_globals *globals = __cxa_get_globals ();
 210   globals->uncaughtExceptions += 1;
 211
 212 #ifdef __USING_SJLJ_EXCEPTIONS__
 213   _Unwind_SjLj_RaiseException (&dep->unwindHeader);
 214 #else
 215   _Unwind_RaiseException (&dep->unwindHeader);
 216 #endif
 217
 218   // Some sort of unwinding error.  Note that terminate is a handler.
 219   __cxa_begin_catch (&dep->unwindHeader);
 220   std::terminate();
 221 }
 222
 223 #undef _GLIBCXX_EH_PTR_COMPAT