1 // Exception Handling support header (exception_ptr class) for -*- C++ -*-
2 
3 // Copyright (C) 2008-2020 Free Software Foundation, Inc.
4 //
5 // This file is part of GCC.
6 //
7 // GCC is free software; you can redistribute it and/or modify
8 // it under the terms of the GNU General Public License as published by
9 // the Free Software Foundation; either version 3, or (at your option)
10 // any later version.
11 //
12 // GCC is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 // GNU General Public License for more details.
16 //
17 // Under Section 7 of GPL version 3, you are granted additional
18 // permissions described in the GCC Runtime Library Exception, version
19 // 3.1, as published by the Free Software Foundation.
20 
21 // You should have received a copy of the GNU General Public License and
22 // a copy of the GCC Runtime Library Exception along with this program;
23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
24 // <http://www.gnu.org/licenses/>.
25 
26 /** @file bits/exception_ptr.h
27  *  This is an internal header file, included by other library headers.
28  *  Do not attempt to use it directly. @headername{exception}
29  */
30 
31 #ifndef _EXCEPTION_PTR_H
32 #define _EXCEPTION_PTR_H
33 
34 #pragma GCC visibility push(default)
35 
36 #include <bits/c++config.h>
37 #include <bits/exception_defines.h>
38 #include <bits/cxxabi_init_exception.h>
39 #include <typeinfo>
40 #include <new>
41 
42 extern "C++" {
43 
44 namespace std
45 {
46   class type_info;
47 
48   /**
49    * @addtogroup exceptions
50    * @{
51    */
52 
53   namespace __exception_ptr
54   {
55     class exception_ptr;
56   }
57 
58   using __exception_ptr::exception_ptr;
59 
60   /** Obtain an exception_ptr to the currently handled exception. If there
61    *  is none, or the currently handled exception is foreign, return the null
62    *  value.
63    */
64   exception_ptr current_exception() _GLIBCXX_USE_NOEXCEPT;
65 
66   template<typename _Ex>
67   exception_ptr make_exception_ptr(_Ex) _GLIBCXX_USE_NOEXCEPT;
68 
69   /// Throw the object pointed to by the exception_ptr.
70   void rethrow_exception(exception_ptr) __attribute__ ((__noreturn__));
71 
72   namespace __exception_ptr
73   {
74     using std::rethrow_exception;
75 
76     /**
77      *  @brief An opaque pointer to an arbitrary exception.
78      *  @ingroup exceptions
79      */
80     class exception_ptr
81     {
82       void* _M_exception_object;
83 
84       explicit exception_ptr(void* __e) _GLIBCXX_USE_NOEXCEPT;
85 
86       void _M_addref() _GLIBCXX_USE_NOEXCEPT;
87       void _M_release() _GLIBCXX_USE_NOEXCEPT;
88 
89       void *_M_get() const _GLIBCXX_NOEXCEPT __attribute__ ((__pure__));
90 
91       friend exception_ptr std::current_exception() _GLIBCXX_USE_NOEXCEPT;
92       friend void std::rethrow_exception(exception_ptr);
93       template<typename _Ex>
94       friend exception_ptr std::make_exception_ptr(_Ex) _GLIBCXX_USE_NOEXCEPT;
95 
96     public:
97       exception_ptr() _GLIBCXX_USE_NOEXCEPT;
98 
99       exception_ptr(const exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
100 
101 #if __cplusplus >= 201103L
exception_ptr(nullptr_t)102       exception_ptr(nullptr_t) noexcept
103       : _M_exception_object(0)
104       { }
105 
exception_ptr(exception_ptr && __o)106       exception_ptr(exception_ptr&& __o) noexcept
107       : _M_exception_object(__o._M_exception_object)
108       { __o._M_exception_object = 0; }
109 #endif
110 
111 #if (__cplusplus < 201103L) || defined (_GLIBCXX_EH_PTR_COMPAT)
112       typedef void (exception_ptr::*__safe_bool)();
113 
114       // For construction from nullptr or 0.
115       exception_ptr(__safe_bool) _GLIBCXX_USE_NOEXCEPT;
116 #endif
117 
118       exception_ptr&
119       operator=(const exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
120 
121 #if __cplusplus >= 201103L
122       exception_ptr&
123       operator=(exception_ptr&& __o) noexcept
124       {
125         exception_ptr(static_cast<exception_ptr&&>(__o)).swap(*this);
126         return *this;
127       }
128 #endif
129 
130       ~exception_ptr() _GLIBCXX_USE_NOEXCEPT;
131 
132       void
133       swap(exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
134 
135 #ifdef _GLIBCXX_EH_PTR_COMPAT
136       // Retained for compatibility with CXXABI_1.3.
137       void _M_safe_bool_dummy() _GLIBCXX_USE_NOEXCEPT
138 	__attribute__ ((__const__));
139       bool operator!() const _GLIBCXX_USE_NOEXCEPT
140 	__attribute__ ((__pure__));
141       operator __safe_bool() const _GLIBCXX_USE_NOEXCEPT;
142 #endif
143 
144 #if __cplusplus >= 201103L
145       explicit operator bool() const
146       { return _M_exception_object; }
147 #endif
148 
149       friend bool
150       operator==(const exception_ptr&, const exception_ptr&)
151 	_GLIBCXX_USE_NOEXCEPT __attribute__ ((__pure__));
152 
153       const class std::type_info*
154       __cxa_exception_type() const _GLIBCXX_USE_NOEXCEPT
155 	__attribute__ ((__pure__));
156     };
157 
158     /// @relates exception_ptr @{
159 
160     bool
161     operator==(const exception_ptr&, const exception_ptr&)
162       _GLIBCXX_USE_NOEXCEPT __attribute__ ((__pure__));
163 
164     bool
165     operator!=(const exception_ptr&, const exception_ptr&)
166       _GLIBCXX_USE_NOEXCEPT __attribute__ ((__pure__));
167 
168     inline void
swap(exception_ptr & __lhs,exception_ptr & __rhs)169     swap(exception_ptr& __lhs, exception_ptr& __rhs)
170     { __lhs.swap(__rhs); }
171 
172     // @}
173 
174     /// @cond undocumented
175     template<typename _Ex>
176       inline void
__dest_thunk(void * __x)177       __dest_thunk(void* __x)
178       { static_cast<_Ex*>(__x)->~_Ex(); }
179     /// @endcond
180 
181   } // namespace __exception_ptr
182 
183   /// Obtain an exception_ptr pointing to a copy of the supplied object.
184   template<typename _Ex>
185     exception_ptr
make_exception_ptr(_Ex __ex)186     make_exception_ptr(_Ex __ex) _GLIBCXX_USE_NOEXCEPT
187     {
188 #if __cpp_exceptions && __cpp_rtti && !_GLIBCXX_HAVE_CDTOR_CALLABI
189       void* __e = __cxxabiv1::__cxa_allocate_exception(sizeof(_Ex));
190       (void) __cxxabiv1::__cxa_init_primary_exception(
191 	  __e, const_cast<std::type_info*>(&typeid(__ex)),
192 	  __exception_ptr::__dest_thunk<_Ex>);
193       try
194 	{
195           ::new (__e) _Ex(__ex);
196           return exception_ptr(__e);
197 	}
198       catch(...)
199 	{
200 	  __cxxabiv1::__cxa_free_exception(__e);
201 	  return current_exception();
202 	}
203 #elif __cpp_exceptions
204       try
205 	{
206           throw __ex;
207 	}
208       catch(...)
209 	{
210 	  return current_exception();
211 	}
212 #else // no RTTI and no exceptions
213       return exception_ptr();
214 #endif
215     }
216 
217   /// @} group exceptions
218 } // namespace std
219 
220 } // extern "C++"
221 
222 #pragma GCC visibility pop
223 
224 #endif
225