1// -*- C++ -*- Implement the members of exception_ptr.
2// Copyright (C) 2008-2017 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
34using namespace __cxxabiv1;
35
36// Verify assumptions about member layout in exception types
37namespace
38{
39template<typename Ex>
40 constexpr std::size_t unwindhdr()
41 { return offsetof(Ex, unwindHeader); }
42
43template<typename Ex>
44 constexpr std::size_t termHandler()
45 { return unwindhdr<Ex>() - offsetof(Ex, terminateHandler); }
46
47static_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__
53template<typename Ex>
54 constexpr std::ptrdiff_t adjptr()
55 { return unwindhdr<Ex>() - offsetof(Ex, adjustedPtr); }
56
57static_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
64std::__exception_ptr::exception_ptr::exception_ptr() noexcept
65: _M_exception_object(0) { }
66
67
68std::__exception_ptr::exception_ptr::exception_ptr(void* obj) noexcept
69: _M_exception_object(obj) { _M_addref(); }
70
71
72std::__exception_ptr::exception_ptr::exception_ptr(__safe_bool) noexcept
73: _M_exception_object(0) { }
74
75
76std::__exception_ptr::
77exception_ptr::exception_ptr(const exception_ptr& other) noexcept
78: _M_exception_object(other._M_exception_object)
79{ _M_addref(); }
80
81
82std::__exception_ptr::exception_ptr::~exception_ptr() noexcept
83{ _M_release(); }
84
85
86std::__exception_ptr::exception_ptr&
87std::__exception_ptr::
88exception_ptr::operator=(const exception_ptr& other) noexcept
89{
90 exception_ptr(other).swap(*this);
91 return *this;
92}
93
94
95void
96std::__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
107void
108std::__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
126void*
127std::__exception_ptr::exception_ptr::_M_get() const noexcept
128{ return _M_exception_object; }
129
130
131void
132std::__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.
141void
142std::__exception_ptr::exception_ptr::_M_safe_bool_dummy() noexcept { }
143
144
145// Retained for compatibility with CXXABI_1.3.
146bool
147std::__exception_ptr::exception_ptr::operator!() const noexcept
148{ return _M_exception_object == 0; }
149
150
151// Retained for compatibility with CXXABI_1.3.
152std::__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
158const std::type_info*
159std::__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
166bool 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
171bool std::__exception_ptr::operator!=(const exception_ptr& lhs,
172 const exception_ptr& rhs) noexcept
173{ return !(lhs == rhs);}
174
175
176std::exception_ptr
177std::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
194static 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
222void
223std::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