1// -*- C++ -*- Exception handling routines for catching.
2// Copyright (C) 2001-2017 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 <cstdlib>
26#include "unwind-cxx.h"
27
28using namespace __cxxabiv1;
29
30extern "C" void *
31__cxxabiv1::__cxa_get_exception_ptr(void *exc_obj_in) _GLIBCXX_NOTHROW
32{
33 _Unwind_Exception *exceptionObject
34 = reinterpret_cast <_Unwind_Exception *>(exc_obj_in);
35
36 return __gxx_caught_object(exceptionObject);
37}
38
39extern "C" void *
40__cxxabiv1::__cxa_begin_catch (void *exc_obj_in) _GLIBCXX_NOTHROW
41{
42 _Unwind_Exception *exceptionObject
43 = reinterpret_cast <_Unwind_Exception *>(exc_obj_in);
44 __cxa_eh_globals *globals = __cxa_get_globals ();
45 __cxa_exception *prev = globals->caughtExceptions;
46 __cxa_exception *header = __get_exception_header_from_ue (exceptionObject);
47 void* objectp;
48
49 // Foreign exceptions can't be stacked here. If the exception stack is
50 // empty, then fine. Otherwise we really have no choice but to terminate.
51 // Note that this use of "header" is a lie. It's fine so long as we only
52 // examine header->unwindHeader though.
53 if (!__is_gxx_exception_class(header->unwindHeader.exception_class))
54 {
55 if (prev != 0)
56 std::terminate ();
57
58 // Remember for end_catch and rethrow.
59 globals->caughtExceptions = header;
60
61 // ??? No sensible value to return; we don't know what the
62 // object is, much less where it is in relation to the header.
63 return 0;
64 }
65
66 int count = header->handlerCount;
67 // Count is less than zero if this exception was rethrown from an
68 // immediately enclosing region.
69 if (count < 0)
70 count = -count + 1;
71 else
72 count += 1;
73 header->handlerCount = count;
74 globals->uncaughtExceptions -= 1;
75
76 if (header != prev)
77 {
78 header->nextException = prev;
79 globals->caughtExceptions = header;
80 }
81
82 objectp = __gxx_caught_object(exceptionObject);
83
84 PROBE2 (catch, objectp, header->exceptionType);
85
86#ifdef __ARM_EABI_UNWINDER__
87 _Unwind_Complete(exceptionObject);
88#endif
89 return objectp;
90}
91
92
93extern "C" void
94__cxxabiv1::__cxa_end_catch ()
95{
96 __cxa_eh_globals *globals = __cxa_get_globals_fast ();
97 __cxa_exception *header = globals->caughtExceptions;
98
99 // A rethrow of a foreign exception will be removed from the
100 // the exception stack immediately by __cxa_rethrow.
101 if (!header)
102 return;
103
104 // A foreign exception couldn't have been stacked (see above),
105 // so by definition processing must be complete.
106 if (!__is_gxx_exception_class(header->unwindHeader.exception_class))
107 {
108 globals->caughtExceptions = 0;
109 _Unwind_DeleteException (&header->unwindHeader);
110 return;
111 }
112
113 int count = header->handlerCount;
114 if (count < 0)
115 {
116 // This exception was rethrown. Decrement the (inverted) catch
117 // count and remove it from the chain when it reaches zero.
118 if (++count == 0)
119 globals->caughtExceptions = header->nextException;
120 }
121 else if (--count == 0)
122 {
123 // Handling for this exception is complete. Destroy the object.
124 globals->caughtExceptions = header->nextException;
125 _Unwind_DeleteException (&header->unwindHeader);
126 return;
127 }
128 else if (count < 0)
129 // A bug in the exception handling library or compiler.
130 std::terminate ();
131
132 header->handlerCount = count;
133}
134
135
136bool
137std::uncaught_exception() throw()
138{
139#if __cpp_exceptions
140 __cxa_eh_globals *globals = __cxa_get_globals ();
141 return globals->uncaughtExceptions != 0;
142#else
143 return false;
144#endif
145}
146
147int
148std::uncaught_exceptions() throw()
149{
150#if __cpp_exceptions
151 __cxa_eh_globals *globals = __cxa_get_globals ();
152 return globals->uncaughtExceptions;
153#else
154 return 0;
155#endif
156}
157