libstdc++-v3/libsupc++/eh_globals.cc

   1 // -*- C++ -*- Manage the thread-local exception globals.
   2 // Copyright (C) 2001-2022 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*
  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*
  57 __cxxabiv1::__cxa_get_globals_fast() _GLIBCXX_NOTHROW
  58 { return get_global(); }
  59
  60 extern "C" __cxa_eh_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
  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
  95   __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
 101   ~__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*
 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*
 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*
 150 __cxxabiv1::__cxa_get_globals_fast() _GLIBCXX_NOTHROW
 151 { return &eh_globals; }
 152
 153 extern "C" __cxa_eh_globals*
 154 __cxxabiv1::__cxa_get_globals() _GLIBCXX_NOTHROW
 155 { return &eh_globals; }
 156
 157 #endif
 158
 159 #endif