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
36using namespace __cxxabiv1;
37
38// Verify assumptions about member layout in exception types
39namespace
40{
41template<typename Ex>
42  constexpr std::size_t unwindhdr()
43  { return offsetof(Ex, unwindHeader); }
44
45template<typename Ex>
46  constexpr std::size_t termHandler()
47  { return unwindhdr<Ex>() - offsetof(Ex, terminateHandler); }
48
49static_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__
55template<typename Ex>
56  constexpr std::ptrdiff_t adjptr()
57  { return unwindhdr<Ex>() - offsetof(Ex, adjustedPtr); }
58
59static_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
66std::__exception_ptr::exception_ptr::exception_ptr() _GLIBCXX_USE_NOEXCEPT
67: _M_exception_object(0) { }
68
69
70std::__exception_ptr::exception_ptr::exception_ptr(void* obj)
71_GLIBCXX_USE_NOEXCEPT
72: _M_exception_object(obj)  { _M_addref(); }
73
74
75std::__exception_ptr::exception_ptr::exception_ptr(__safe_bool)
76_GLIBCXX_USE_NOEXCEPT
77: _M_exception_object(0) { }
78
79
80std::__exception_ptr::
81exception_ptr::exception_ptr(const exception_ptr& other) _GLIBCXX_USE_NOEXCEPT
82: _M_exception_object(other._M_exception_object)
83{ _M_addref(); }
84
85
86std::__exception_ptr::exception_ptr::~exception_ptr() _GLIBCXX_USE_NOEXCEPT
87{ _M_release(); }
88
89
90std::__exception_ptr::exception_ptr&
91std::__exception_ptr::
92exception_ptr::operator=(const exception_ptr& other) _GLIBCXX_USE_NOEXCEPT
93{
94  exception_ptr(other).swap(*this);
95  return *this;
96}
97
98
99void
100std::__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
111void
112std::__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
130void*
131std::__exception_ptr::exception_ptr::_M_get() const _GLIBCXX_USE_NOEXCEPT
132{ return _M_exception_object; }
133
134
135void
136std::__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.
146void
147std::__exception_ptr::exception_ptr::_M_safe_bool_dummy()
148  _GLIBCXX_USE_NOEXCEPT { }
149
150
151// Retained for compatibility with CXXABI_1.3.
152bool
153std::__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.
158std::__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
165const std::type_info*
166std::__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
174bool 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
180bool std::__exception_ptr::operator!=(const exception_ptr& lhs,
181				      const exception_ptr& rhs)
182  _GLIBCXX_USE_NOEXCEPT
183{ return !(lhs == rhs);}
184
185
186std::exception_ptr
187std::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
204static 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
232void
233std::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 _GLIBCXX_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
265