1 // -*- C++ -*- Manage the thread-local exception globals.
2 // Copyright (C) 2001-2016 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 <exception>
27 #include <cstdlib>
28 #include "cxxabi.h"
29 #include "unwind-cxx.h"
30 #include "bits/gthr.h"
31 
32 #if _GLIBCXX_HOSTED
33 using std::free;
34 using std::malloc;
35 #else
36 // In a freestanding environment, these functions may not be
37 // available -- but for now, we assume that they are.
38 extern "C" void *malloc (std::size_t);
39 extern "C" void free(void *);
40 #endif
41 
42 using namespace __cxxabiv1;
43 
44 #if _GLIBCXX_HAVE_TLS
45 
46 namespace
47 {
48   abi::__cxa_eh_globals*
get_global()49   get_global() _GLIBCXX_NOTHROW
50   {
51     static __thread abi::__cxa_eh_globals global;
52     return &global;
53   }
54 } // anonymous namespace
55 
56 extern "C" __cxa_eh_globals*
__cxa_get_globals_fast()57 __cxxabiv1::__cxa_get_globals_fast() _GLIBCXX_NOTHROW
58 { return get_global(); }
59 
60 extern "C" __cxa_eh_globals*
__cxa_get_globals()61 __cxxabiv1::__cxa_get_globals() _GLIBCXX_NOTHROW
62 { return get_global(); }
63 
64 
65 #else
66 
67 // Single-threaded fallback buffer.
68 static __cxa_eh_globals eh_globals;
69 
70 #if __GTHREADS
71 
72 static void
eh_globals_dtor(void * ptr)73 eh_globals_dtor(void* ptr)
74 {
75   if (ptr)
76     {
77       __cxa_eh_globals* g = reinterpret_cast<__cxa_eh_globals*>(ptr);
78       __cxa_exception* exn = g->caughtExceptions;
79       __cxa_exception* next;
80       while (exn)
81 	{
82 	  next = exn->nextException;
83 	  _Unwind_DeleteException(&exn->unwindHeader);
84 	  exn = next;
85 	}
86       free(ptr);
87     }
88 }
89 
90 struct __eh_globals_init
91 {
92   __gthread_key_t  	_M_key;
93   bool 			_M_init;
94 
__eh_globals_init__eh_globals_init95   __eh_globals_init() : _M_init(false)
96   {
97     if (__gthread_active_p())
98       _M_init = __gthread_key_create(&_M_key, eh_globals_dtor) == 0;
99   }
100 
~__eh_globals_init__eh_globals_init101   ~__eh_globals_init()
102   {
103     if (_M_init)
104       __gthread_key_delete(_M_key);
105     _M_init = false;
106   }
107 };
108 
109 static __eh_globals_init init;
110 
111 extern "C" __cxa_eh_globals*
__cxa_get_globals_fast()112 __cxxabiv1::__cxa_get_globals_fast() _GLIBCXX_NOTHROW
113 {
114   __cxa_eh_globals* g;
115   if (init._M_init)
116     g = static_cast<__cxa_eh_globals*>(__gthread_getspecific(init._M_key));
117   else
118     g = &eh_globals;
119   return g;
120 }
121 
122 extern "C" __cxa_eh_globals*
__cxa_get_globals()123 __cxxabiv1::__cxa_get_globals() _GLIBCXX_NOTHROW
124 {
125   __cxa_eh_globals* g;
126   if (init._M_init)
127     {
128       g = static_cast<__cxa_eh_globals*>(__gthread_getspecific(init._M_key));
129       if (!g)
130 	{
131 	  void* v = malloc(sizeof(__cxa_eh_globals));
132 	  if (v == 0 || __gthread_setspecific(init._M_key, v) != 0)
133 	    std::terminate();
134 	  g = static_cast<__cxa_eh_globals*>(v);
135 	  g->caughtExceptions = 0;
136 	  g->uncaughtExceptions = 0;
137 #ifdef __ARM_EABI_UNWINDER__
138 	  g->propagatingExceptions = 0;
139 #endif
140 	}
141     }
142   else
143     g = &eh_globals;
144   return g;
145 }
146 
147 #else
148 
149 extern "C" __cxa_eh_globals*
__cxa_get_globals_fast()150 __cxxabiv1::__cxa_get_globals_fast() _GLIBCXX_NOTHROW
151 { return &eh_globals; }
152 
153 extern "C" __cxa_eh_globals*
__cxa_get_globals()154 __cxxabiv1::__cxa_get_globals() _GLIBCXX_NOTHROW
155 { return &eh_globals; }
156 
157 #endif
158 
159 #endif
160