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

   1 // -*- C++ -*- Implement the members of exception_ptr.
   2 // Copyright (C) 2008-2015 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() _GLIBCXX_USE_NOEXCEPT
  67 : _M_exception_object(0) { }
  68
  69
  70 std::__exception_ptr::exception_ptr::exception_ptr(void* obj)
  71 _GLIBCXX_USE_NOEXCEPT
  72 : _M_exception_object(obj)  { _M_addref(); }
  73
  74
  75 std::__exception_ptr::exception_ptr::exception_ptr(__safe_bool)
  76 _GLIBCXX_USE_NOEXCEPT
  77 : _M_exception_object(0) { }
  78
  79
  80 std::__exception_ptr::
  81 exception_ptr::exception_ptr(const exception_ptr& other) _GLIBCXX_USE_NOEXCEPT
  82 : _M_exception_object(other._M_exception_object)
  83 { _M_addref(); }
  84
  85
  86 std::__exception_ptr::exception_ptr::~exception_ptr() _GLIBCXX_USE_NOEXCEPT
  87 { _M_release(); }
  88
  89
  90 std::__exception_ptr::exception_ptr&
  91 std::__exception_ptr::
  92 exception_ptr::operator=(const exception_ptr& other) _GLIBCXX_USE_NOEXCEPT
  93 {
  94   exception_ptr(other).swap(*this);
  95   return *this;
  96 }
  97
  98
  99 void
 100 std::__exception_ptr::exception_ptr::_M_addref() _GLIBCXX_USE_NOEXCEPT
 101 {
 102   if (_M_exception_object)
 103     {
 104       __cxa_refcounted_exception *eh =
 105         __get_refcounted_exception_header_from_obj (_M_exception_object);
 106       __atomic_add_fetch (&eh->referenceCount, 1, __ATOMIC_ACQ_REL);
 107     }
 108 }
 109
 110
 111 void
 112 std::__exception_ptr::exception_ptr::_M_release() _GLIBCXX_USE_NOEXCEPT
 113 {
 114   if (_M_exception_object)
 115     {
 116       __cxa_refcounted_exception *eh =
 117         __get_refcounted_exception_header_from_obj (_M_exception_object);
 118       if (__atomic_sub_fetch (&eh->referenceCount, 1, __ATOMIC_ACQ_REL) == 0)
 119         {
 120           if (eh->exc.exceptionDestructor)
 121             eh->exc.exceptionDestructor (_M_exception_object);
 122
 123           __cxa_free_exception (_M_exception_object);
 124           _M_exception_object = 0;
 125         }
 126     }
 127 }
 128
 129
 130 void*
 131 std::__exception_ptr::exception_ptr::_M_get() const _GLIBCXX_USE_NOEXCEPT
 132 { return _M_exception_object; }
 133
 134
 135 void
 136 std::__exception_ptr::exception_ptr::swap(exception_ptr &other)
 137   _GLIBCXX_USE_NOEXCEPT
 138 {
 139   void *tmp = _M_exception_object;
 140   _M_exception_object = other._M_exception_object;
 141   other._M_exception_object = tmp;
 142 }
 143
 144
 145 // Retained for compatibility with CXXABI_1.3.
 146 void
 147 std::__exception_ptr::exception_ptr::_M_safe_bool_dummy()
 148   _GLIBCXX_USE_NOEXCEPT { }
 149
 150
 151 // Retained for compatibility with CXXABI_1.3.
 152 bool
 153 std::__exception_ptr::exception_ptr::operator!() const _GLIBCXX_USE_NOEXCEPT
 154 { return _M_exception_object == 0; }
 155
 156
 157 // Retained for compatibility with CXXABI_1.3.
 158 std::__exception_ptr::exception_ptr::operator __safe_bool() const
 159 _GLIBCXX_USE_NOEXCEPT
 160 {
 161   return _M_exception_object ? &exception_ptr::_M_safe_bool_dummy : 0;
 162 }
 163
 164
 165 const std::type_info*
 166 std::__exception_ptr::exception_ptr::__cxa_exception_type() const
 167   _GLIBCXX_USE_NOEXCEPT
 168 {
 169   __cxa_exception *eh = __get_exception_header_from_obj (_M_exception_object);
 170   return eh->exceptionType;
 171 }
 172
 173
 174 bool std::__exception_ptr::operator==(const exception_ptr& lhs,
 175                                       const exception_ptr& rhs)
 176   _GLIBCXX_USE_NOEXCEPT
 177 { return lhs._M_exception_object == rhs._M_exception_object; }
 178
 179
 180 bool std::__exception_ptr::operator!=(const exception_ptr& lhs,
 181                                       const exception_ptr& rhs)
 182   _GLIBCXX_USE_NOEXCEPT
 183 { return !(lhs == rhs);}
 184
 185
 186 std::exception_ptr
 187 std::current_exception() _GLIBCXX_USE_NOEXCEPT
 188 {
 189   __cxa_eh_globals *globals = __cxa_get_globals ();
 190   __cxa_exception *header = globals->caughtExceptions;
 191
 192   if (!header)
 193     return std::exception_ptr();
 194
 195   // Since foreign exceptions can't be counted, we can't return them.
 196   if (!__is_gxx_exception_class (header->unwindHeader.exception_class))
 197     return std::exception_ptr();
 198
 199   return std::exception_ptr(
 200     __get_object_from_ambiguous_exception (header));
 201 }
 202
 203
 204 static void
 205 __gxx_dependent_exception_cleanup(_Unwind_Reason_Code code,
 206                                   _Unwind_Exception *exc)
 207 {
 208   // This cleanup is set only for dependents.
 209   __cxa_dependent_exception *dep = __get_dependent_exception_from_ue (exc);
 210   __cxa_refcounted_exception *header =
 211     __get_refcounted_exception_header_from_obj (dep->primaryException);
 212
 213   // We only want to be called through _Unwind_DeleteException.
 214   // _Unwind_DeleteException in the HP-UX IA64 libunwind library
 215   // returns _URC_NO_REASON and not _URC_FOREIGN_EXCEPTION_CAUGHT
 216   // like the GCC _Unwind_DeleteException function does.
 217   if (code != _URC_FOREIGN_EXCEPTION_CAUGHT && code != _URC_NO_REASON)
 218     __terminate (header->exc.terminateHandler);
 219
 220   __cxa_free_dependent_exception (dep);
 221
 222   if (__atomic_sub_fetch (&header->referenceCount, 1, __ATOMIC_ACQ_REL) == 0)
 223     {
 224       if (header->exc.exceptionDestructor)
 225         header->exc.exceptionDestructor (header + 1);
 226
 227       __cxa_free_exception (header + 1);
 228     }
 229 }
 230
 231
 232 void
 233 std::rethrow_exception(std::exception_ptr ep)
 234 {
 235   void *obj = ep._M_get();
 236   __cxa_refcounted_exception *eh
 237     = __get_refcounted_exception_header_from_obj (obj);
 238
 239   __cxa_dependent_exception *dep = __cxa_allocate_dependent_exception ();
 240   dep->primaryException = obj;
 241   __atomic_add_fetch (&eh->referenceCount, 1,  __ATOMIC_ACQ_REL);
 242
 243   dep->unexpectedHandler = get_unexpected ();
 244   dep->terminateHandler = get_terminate ();
 245   __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(dep->unwindHeader.exception_class);
 246   dep->unwindHeader.exception_cleanup = __gxx_dependent_exception_cleanup;
 247
 248   __cxa_eh_globals *globals = __cxa_get_globals ();
 249   globals->uncaughtExceptions += 1;
 250
 251 #ifdef __USING_SJLJ_EXCEPTIONS__
 252   _Unwind_SjLj_RaiseException (&dep->unwindHeader);
 253 #else
 254   _Unwind_RaiseException (&dep->unwindHeader);
 255 #endif
 256
 257   // Some sort of unwinding error.  Note that terminate is a handler.
 258   __cxa_begin_catch (&dep->unwindHeader);
 259   std::terminate();
 260 }
 261
 262 #undef _GLIBCXX_EH_PTR_COMPAT
 263
 264 #endif