1 // -*- C++ -*- Exception handling routines for catching.
2 // Copyright (C) 2001-2018 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 <cstdlib>
26 #include "unwind-cxx.h"
27 
28 using namespace __cxxabiv1;
29 
30 extern "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 
39 extern "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 
93 extern "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 
136 bool
137 std::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 
147 int
148 std::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