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

   1 // -*- C++ -*- Exception handling routines for catching.
   2 // Copyright (C) 2001 Free Software Foundation, Inc.
   3 //
   4 // This file is part of GNU CC.
   5 //
   6 // GNU CC 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 2, or (at your option)
   9 // any later version.
  10 //
  11 // GNU CC 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 // You should have received a copy of the GNU General Public License
  17 // along with GNU CC; see the file COPYING.  If not, write to
  18 // the Free Software Foundation, 59 Temple Place - Suite 330,
  19 // Boston, MA 02111-1307, USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30
  31 #include <cstdlib>
  32 #include "unwind-cxx.h"
  33
  34 using namespace __cxxabiv1;
  35
  36
  37 extern "C" void *
  38 __cxa_begin_catch (_Unwind_Exception *exceptionObject)
  39 {
  40   // ??? Foreign exceptions can't be stacked here, and there doesn't
  41   // appear to be any place to store for __cxa_end_catch to destroy.
  42
  43   __cxa_exception *header = __get_exception_header_from_ue (exceptionObject);
  44   __cxa_eh_globals *globals = __cxa_get_globals ();
  45   __cxa_exception *prev = globals->caughtExceptions;
  46   int count = header->handlerCount;
  47
  48   if (count < 0)
  49     // This exception was rethrown from an immediately enclosing region.
  50     count = -count + 1;
  51   else
  52     count += 1;
  53   header->handlerCount = count;
  54
  55   globals->uncaughtExceptions -= 1;
  56   if (header != prev)
  57     {
  58       header->nextException = prev;
  59       globals->caughtExceptions = header;
  60     }
  61
  62   return header->adjustedPtr;
  63 }
  64
  65
  66 extern "C" void
  67 __cxa_end_catch ()
  68 {
  69   __cxa_eh_globals *globals = __cxa_get_globals_fast ();
  70   __cxa_exception *header = globals->caughtExceptions;
  71   int count = header->handlerCount;
  72
  73   if (count < 0)
  74     {
  75       // This exception was rethrown.  Decrement the (inverted) catch
  76       // count and remove it from the chain when it reaches zero.
  77       if (++count == 0)
  78         {
  79           globals->uncaughtExceptions += 1;
  80           globals->caughtExceptions = header->nextException;
  81         }
  82     }
  83   else if (--count == 0)
  84     {
  85       // Handling for this exception is complete.  Destroy the object.
  86       globals->caughtExceptions = header->nextException;
  87       _Unwind_DeleteException (&header->unwindHeader);
  88       return;
  89     }
  90   else if (count < 0)
  91     // A bug in the exception handling library or compiler.
  92     std::abort ();
  93
  94   header->handlerCount = count;
  95 }
  96
  97
  98 bool
  99 std::uncaught_exception() throw()
 100 {
 101   __cxa_eh_globals *globals = __cxa_get_globals ();
 102   return globals->uncaughtExceptions != 0;
 103 }