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
253