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

   1 // -*- C++ -*- Implement the members of exception_ptr.
   2 // Copyright (C) 2008-2016 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 <bits/atomic_lockfree_defines.h>
  27
  28 #if ATOMIC_INT_LOCK_FREE > 1
  29
  30 #define _GLIBCXX_EH_PTR_COMPAT
  31
  32 #include <exception>
  33 #include <bits/exception_ptr.h>
  34 #include "unwind-cxx.h"
  35
  36 using namespace __cxxabiv1;
  37
  38 // Verify assumptions about member layout in exception types
  39 namespace
  40 {
  41 template<typename Ex>
  42   constexpr std::size_t unwindhdr()
  43   { return offsetof(Ex, unwindHeader); }
  44
  45 template<typename Ex>
  46   constexpr std::size_t termHandler()
  47   { return unwindhdr<Ex>() - offsetof(Ex, terminateHandler); }
  48
  49 static_assert( termHandler<__cxa_exception>()
  50                == termHandler<__cxa_dependent_exception>(),
  51                "__cxa_dependent_exception::termHandler layout must be"
  52                " consistent with __cxa_exception::termHandler" );
  53
  54 #ifndef __ARM_EABI_UNWINDER__
  55 template<typename Ex>
  56   constexpr std::ptrdiff_t adjptr()
  57   { return unwindhdr<Ex>() - offsetof(Ex, adjustedPtr); }
  58
  59 static_assert( adjptr<__cxa_exception>()
  60                == adjptr<__cxa_dependent_exception>(),
  61                "__cxa_dependent_exception::adjustedPtr layout must be"
  62                " consistent with __cxa_exception::adjustedPtr" );
  63 #endif
  64 }
  65
  66 std::__exception_ptr::exception_ptr::exception_ptr() noexcept
  67 : _M_exception_object(0) { }
  68
  69
  70 std::__exception_ptr::exception_ptr::exception_ptr(void* obj) noexcept
  71 : _M_exception_object(obj)  { _M_addref(); }
  72
  73
  74 std::__exception_ptr::exception_ptr::exception_ptr(__safe_bool) noexcept
  75 : _M_exception_object(0) { }
  76
  77
  78 std::__exception_ptr::
  79 exception_ptr::exception_ptr(const exception_ptr& other) noexcept
  80 : _M_exception_object(other._M_exception_object)
  81 { _M_addref(); }
  82
  83
  84 std::__exception_ptr::exception_ptr::~exception_ptr() noexcept
  85 { _M_release(); }
  86
  87
  88 std::__exception_ptr::exception_ptr&
  89 std::__exception_ptr::
  90 exception_ptr::operator=(const exception_ptr& other) noexcept
  91 {
  92   exception_ptr(other).swap(*this);
  93   return *this;
  94 }
  95
  96
  97 void
  98 std::__exception_ptr::exception_ptr::_M_addref() noexcept
  99 {
 100   if (_M_exception_object)
 101     {
 102       __cxa_refcounted_exception *eh =
 103         __get_refcounted_exception_header_from_obj (_M_exception_object);
 104       __atomic_add_fetch (&eh->referenceCount, 1, __ATOMIC_ACQ_REL);
 105     }
 106 }
 107
 108
 109 void
 110 std::__exception_ptr::exception_ptr::_M_release() noexcept
 111 {
 112   if (_M_exception_object)
 113     {
 114       __cxa_refcounted_exception *eh =
 115         __get_refcounted_exception_header_from_obj (_M_exception_object);
 116       if (__atomic_sub_fetch (&eh->referenceCount, 1, __ATOMIC_ACQ_REL) == 0)
 117         {
 118           if (eh->exc.exceptionDestructor)
 119             eh->exc.exceptionDestructor (_M_exception_object);
 120
 121           __cxa_free_exception (_M_exception_object);
 122           _M_exception_object = 0;
 123         }
 124     }
 125 }
 126
 127
 128 void*
 129 std::__exception_ptr::exception_ptr::_M_get() const noexcept
 130 { return _M_exception_object; }
 131
 132
 133 void
 134 std::__exception_ptr::exception_ptr::swap(exception_ptr &other) noexcept
 135 {
 136   void *tmp = _M_exception_object;
 137   _M_exception_object = other._M_exception_object;
 138   other._M_exception_object = tmp;
 139 }
 140
 141
 142 // Retained for compatibility with CXXABI_1.3.
 143 void
 144 std::__exception_ptr::exception_ptr::_M_safe_bool_dummy() noexcept { }
 145
 146
 147 // Retained for compatibility with CXXABI_1.3.
 148 bool
 149 std::__exception_ptr::exception_ptr::operator!() const noexcept
 150 { return _M_exception_object == 0; }
 151
 152
 153 // Retained for compatibility with CXXABI_1.3.
 154 std::__exception_ptr::exception_ptr::operator __safe_bool() const noexcept
 155 {
 156   return _M_exception_object ? &exception_ptr::_M_safe_bool_dummy : 0;
 157 }
 158
 159
 160 const std::type_info*
 161 std::__exception_ptr::exception_ptr::__cxa_exception_type() const noexcept
 162 {
 163   __cxa_exception *eh = __get_exception_header_from_obj (_M_exception_object);
 164   return eh->exceptionType;
 165 }
 166
 167
 168 bool std::__exception_ptr::operator==(const exception_ptr& lhs,
 169                                       const exception_ptr& rhs) noexcept
 170 { return lhs._M_exception_object == rhs._M_exception_object; }
 171
 172
 173 bool std::__exception_ptr::operator!=(const exception_ptr& lhs,
 174                                       const exception_ptr& rhs) noexcept
 175 { return !(lhs == rhs);}
 176
 177
 178 std::exception_ptr
 179 std::current_exception() noexcept
 180 {
 181   __cxa_eh_globals *globals = __cxa_get_globals ();
 182   __cxa_exception *header = globals->caughtExceptions;
 183
 184   if (!header)
 185     return std::exception_ptr();
 186
 187   // Since foreign exceptions can't be counted, we can't return them.
 188   if (!__is_gxx_exception_class (header->unwindHeader.exception_class))
 189     return std::exception_ptr();
 190
 191   return std::exception_ptr(
 192     __get_object_from_ambiguous_exception (header));
 193 }
 194
 195
 196 static void
 197 __gxx_dependent_exception_cleanup(_Unwind_Reason_Code code,
 198                                   _Unwind_Exception *exc)
 199 {
 200   // This cleanup is set only for dependents.
 201   __cxa_dependent_exception *dep = __get_dependent_exception_from_ue (exc);
 202   __cxa_refcounted_exception *header =
 203     __get_refcounted_exception_header_from_obj (dep->primaryException);
 204
 205   // We only want to be called through _Unwind_DeleteException.
 206   // _Unwind_DeleteException in the HP-UX IA64 libunwind library
 207   // returns _URC_NO_REASON and not _URC_FOREIGN_EXCEPTION_CAUGHT
 208   // like the GCC _Unwind_DeleteException function does.
 209   if (code != _URC_FOREIGN_EXCEPTION_CAUGHT && code != _URC_NO_REASON)
 210     __terminate (header->exc.terminateHandler);
 211
 212   __cxa_free_dependent_exception (dep);
 213
 214   if (__atomic_sub_fetch (&header->referenceCount, 1, __ATOMIC_ACQ_REL) == 0)
 215     {
 216       if (header->exc.exceptionDestructor)
 217         header->exc.exceptionDestructor (header + 1);
 218
 219       __cxa_free_exception (header + 1);
 220     }
 221 }
 222
 223
 224 void
 225 std::rethrow_exception(std::exception_ptr ep)
 226 {
 227   void *obj = ep._M_get();
 228   __cxa_refcounted_exception *eh
 229     = __get_refcounted_exception_header_from_obj (obj);
 230
 231   __cxa_dependent_exception *dep = __cxa_allocate_dependent_exception ();
 232   dep->primaryException = obj;
 233   __atomic_add_fetch (&eh->referenceCount, 1,  __ATOMIC_ACQ_REL);
 234
 235   dep->unexpectedHandler = get_unexpected ();
 236   dep->terminateHandler = get_terminate ();
 237   __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(dep->unwindHeader.exception_class);
 238   dep->unwindHeader.exception_cleanup = __gxx_dependent_exception_cleanup;
 239
 240   __cxa_eh_globals *globals = __cxa_get_globals ();
 241   globals->uncaughtExceptions += 1;
 242
 243 #ifdef __USING_SJLJ_EXCEPTIONS__
 244   _Unwind_SjLj_RaiseException (&dep->unwindHeader);
 245 #else
 246   _Unwind_RaiseException (&dep->unwindHeader);
 247 #endif
 248
 249   // Some sort of unwinding error.  Note that terminate is a handler.
 250   __cxa_begin_catch (&dep->unwindHeader);
 251   std::terminate();
 252 }
 253
 254 #undef _GLIBCXX_EH_PTR_COMPAT
 255
 256 #endif