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

   1 // -*- C++ -*- Implement the members of exception_ptr.
   2 // Copyright (C) 2008-2018 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 #define _GLIBCXX_EH_PTR_COMPAT
  29
  30 #include <exception>
  31 #include <bits/exception_ptr.h>
  32 #include "unwind-cxx.h"
  33
  34 using namespace __cxxabiv1;
  35
  36 // Verify assumptions about member layout in exception types
  37 namespace
  38 {
  39 template<typename Ex>
  40   constexpr std::size_t unwindhdr()
  41   { return offsetof(Ex, unwindHeader); }
  42
  43 template<typename Ex>
  44   constexpr std::size_t termHandler()
  45   { return unwindhdr<Ex>() - offsetof(Ex, terminateHandler); }
  46
  47 static_assert( termHandler<__cxa_exception>()
  48                == termHandler<__cxa_dependent_exception>(),
  49                "__cxa_dependent_exception::termHandler layout must be"
  50                " consistent with __cxa_exception::termHandler" );
  51
  52 #ifndef __ARM_EABI_UNWINDER__
  53 template<typename Ex>
  54   constexpr std::ptrdiff_t adjptr()
  55   { return unwindhdr<Ex>() - offsetof(Ex, adjustedPtr); }
  56
  57 static_assert( adjptr<__cxa_exception>()
  58                == adjptr<__cxa_dependent_exception>(),
  59                "__cxa_dependent_exception::adjustedPtr layout must be"
  60                " consistent with __cxa_exception::adjustedPtr" );
  61 #endif
  62 }
  63
  64 std::__exception_ptr::exception_ptr::exception_ptr() noexcept
  65 : _M_exception_object(0) { }
  66
  67
  68 std::__exception_ptr::exception_ptr::exception_ptr(void* obj) noexcept
  69 : _M_exception_object(obj)  { _M_addref(); }
  70
  71
  72 std::__exception_ptr::exception_ptr::exception_ptr(__safe_bool) noexcept
  73 : _M_exception_object(0) { }
  74
  75
  76 std::__exception_ptr::
  77 exception_ptr::exception_ptr(const exception_ptr& other) noexcept
  78 : _M_exception_object(other._M_exception_object)
  79 { _M_addref(); }
  80
  81
  82 std::__exception_ptr::exception_ptr::~exception_ptr() noexcept
  83 { _M_release(); }
  84
  85
  86 std::__exception_ptr::exception_ptr&
  87 std::__exception_ptr::
  88 exception_ptr::operator=(const exception_ptr& other) noexcept
  89 {
  90   exception_ptr(other).swap(*this);
  91   return *this;
  92 }
  93
  94
  95 void
  96 std::__exception_ptr::exception_ptr::_M_addref() noexcept
  97 {
  98   if (_M_exception_object)
  99     {
 100       __cxa_refcounted_exception *eh =
 101         __get_refcounted_exception_header_from_obj (_M_exception_object);
 102       __gnu_cxx::__eh_atomic_inc (&eh->referenceCount);
 103     }
 104 }
 105
 106
 107 void
 108 std::__exception_ptr::exception_ptr::_M_release() noexcept
 109 {
 110   if (_M_exception_object)
 111     {
 112       __cxa_refcounted_exception *eh =
 113         __get_refcounted_exception_header_from_obj (_M_exception_object);
 114       if (__gnu_cxx::__eh_atomic_dec (&eh->referenceCount))
 115         {
 116           if (eh->exc.exceptionDestructor)
 117             eh->exc.exceptionDestructor (_M_exception_object);
 118
 119           __cxa_free_exception (_M_exception_object);
 120           _M_exception_object = 0;
 121         }
 122     }
 123 }
 124
 125
 126 void*
 127 std::__exception_ptr::exception_ptr::_M_get() const noexcept
 128 { return _M_exception_object; }
 129
 130
 131 void
 132 std::__exception_ptr::exception_ptr::swap(exception_ptr &other) noexcept
 133 {
 134   void *tmp = _M_exception_object;
 135   _M_exception_object = other._M_exception_object;
 136   other._M_exception_object = tmp;
 137 }
 138
 139
 140 // Retained for compatibility with CXXABI_1.3.
 141 void
 142 std::__exception_ptr::exception_ptr::_M_safe_bool_dummy() noexcept { }
 143
 144
 145 // Retained for compatibility with CXXABI_1.3.
 146 bool
 147 std::__exception_ptr::exception_ptr::operator!() const noexcept
 148 { return _M_exception_object == 0; }
 149
 150
 151 // Retained for compatibility with CXXABI_1.3.
 152 std::__exception_ptr::exception_ptr::operator __safe_bool() const noexcept
 153 {
 154   return _M_exception_object ? &exception_ptr::_M_safe_bool_dummy : 0;
 155 }
 156
 157
 158 const std::type_info*
 159 std::__exception_ptr::exception_ptr::__cxa_exception_type() const noexcept
 160 {
 161   __cxa_exception *eh = __get_exception_header_from_obj (_M_exception_object);
 162   return eh->exceptionType;
 163 }
 164
 165
 166 bool std::__exception_ptr::operator==(const exception_ptr& lhs,
 167                                       const exception_ptr& rhs) noexcept
 168 { return lhs._M_exception_object == rhs._M_exception_object; }
 169
 170
 171 bool std::__exception_ptr::operator!=(const exception_ptr& lhs,
 172                                       const exception_ptr& rhs) noexcept
 173 { return !(lhs == rhs);}
 174
 175
 176 std::exception_ptr
 177 std::current_exception() noexcept
 178 {
 179   __cxa_eh_globals *globals = __cxa_get_globals ();
 180   __cxa_exception *header = globals->caughtExceptions;
 181
 182   if (!header)
 183     return std::exception_ptr();
 184
 185   // Since foreign exceptions can't be counted, we can't return them.
 186   if (!__is_gxx_exception_class (header->unwindHeader.exception_class))
 187     return std::exception_ptr();
 188
 189   return std::exception_ptr(
 190     __get_object_from_ambiguous_exception (header));
 191 }
 192
 193
 194 static void
 195 __gxx_dependent_exception_cleanup(_Unwind_Reason_Code code,
 196                                   _Unwind_Exception *exc)
 197 {
 198   // This cleanup is set only for dependents.
 199   __cxa_dependent_exception *dep = __get_dependent_exception_from_ue (exc);
 200   __cxa_refcounted_exception *header =
 201     __get_refcounted_exception_header_from_obj (dep->primaryException);
 202
 203   // We only want to be called through _Unwind_DeleteException.
 204   // _Unwind_DeleteException in the HP-UX IA64 libunwind library
 205   // returns _URC_NO_REASON and not _URC_FOREIGN_EXCEPTION_CAUGHT
 206   // like the GCC _Unwind_DeleteException function does.
 207   if (code != _URC_FOREIGN_EXCEPTION_CAUGHT && code != _URC_NO_REASON)
 208     __terminate (header->exc.terminateHandler);
 209
 210   __cxa_free_dependent_exception (dep);
 211
 212   if (__gnu_cxx::__eh_atomic_dec (&header->referenceCount))
 213     {
 214       if (header->exc.exceptionDestructor)
 215         header->exc.exceptionDestructor (header + 1);
 216
 217       __cxa_free_exception (header + 1);
 218     }
 219 }
 220
 221
 222 void
 223 std::rethrow_exception(std::exception_ptr ep)
 224 {
 225   void *obj = ep._M_get();
 226   __cxa_refcounted_exception *eh
 227     = __get_refcounted_exception_header_from_obj (obj);
 228
 229   __cxa_dependent_exception *dep = __cxa_allocate_dependent_exception ();
 230   dep->primaryException = obj;
 231   __gnu_cxx::__eh_atomic_inc (&eh->referenceCount);
 232
 233   dep->unexpectedHandler = get_unexpected ();
 234   dep->terminateHandler = get_terminate ();
 235   __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(dep->unwindHeader.exception_class);
 236   dep->unwindHeader.exception_cleanup = __gxx_dependent_exception_cleanup;
 237
 238   __cxa_eh_globals *globals = __cxa_get_globals ();
 239   globals->uncaughtExceptions += 1;
 240
 241 #ifdef __USING_SJLJ_EXCEPTIONS__
 242   _Unwind_SjLj_RaiseException (&dep->unwindHeader);
 243 #else
 244   _Unwind_RaiseException (&dep->unwindHeader);
 245 #endif
 246
 247   // Some sort of unwinding error.  Note that terminate is a handler.
 248   __cxa_begin_catch (&dep->unwindHeader);
 249   std::terminate();
 250 }
 251
 252 #undef _GLIBCXX_EH_PTR_COMPAT