gomp-20050608-branch/libstdc++-v3/libsupc++/eh_catch.cc

   1 // -*- C++ -*- Exception handling routines for catching.
   2 // Copyright (C) 2001, 2003, 2004 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 2, 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 // You should have received a copy of the GNU General Public License
  17 // along with GCC; see the file COPYING.  If not, write to
  18 // the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  19 // Boston, MA 02110-1301, 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 #include <cstdlib>
  31 #include "unwind-cxx.h"
  32
  33 using namespace __cxxabiv1;
  34
  35 extern "C" void *
  36 __cxxabiv1::__cxa_get_exception_ptr(void *exc_obj_in) throw()
  37 {
  38   _Unwind_Exception *exceptionObject
  39     = reinterpret_cast <_Unwind_Exception *>(exc_obj_in);
  40
  41   return __gxx_caught_object(exceptionObject);
  42 }
  43
  44 extern "C" void *
  45 __cxxabiv1::__cxa_begin_catch (void *exc_obj_in) throw()
  46 {
  47   _Unwind_Exception *exceptionObject
  48     = reinterpret_cast <_Unwind_Exception *>(exc_obj_in);
  49   __cxa_eh_globals *globals = __cxa_get_globals ();
  50   __cxa_exception *prev = globals->caughtExceptions;
  51   __cxa_exception *header = __get_exception_header_from_ue (exceptionObject);
  52   void* objectp;
  53
  54   // Foreign exceptions can't be stacked here.  If the exception stack is
  55   // empty, then fine.  Otherwise we really have no choice but to terminate.
  56   // Note that this use of "header" is a lie.  It's fine so long as we only
  57   // examine header->unwindHeader though.
  58   if (!__is_gxx_exception_class(header->unwindHeader.exception_class))
  59     {
  60       if (prev != 0)
  61         std::terminate ();
  62
  63       // Remember for end_catch and rethrow.
  64       globals->caughtExceptions = header;
  65
  66       // ??? No sensible value to return; we don't know what the
  67       // object is, much less where it is in relation to the header.
  68       return 0;
  69     }
  70
  71   int count = header->handlerCount;
  72   // Count is less than zero if this exception was rethrown from an
  73   // immediately enclosing region.
  74   if (count < 0)
  75     count = -count + 1;
  76   else
  77     count += 1;
  78   header->handlerCount = count;
  79   globals->uncaughtExceptions -= 1;
  80
  81   if (header != prev)
  82     {
  83       header->nextException = prev;
  84       globals->caughtExceptions = header;
  85     }
  86
  87   objectp = __gxx_caught_object(exceptionObject);
  88 #ifdef __ARM_EABI_UNWINDER__
  89   _Unwind_Complete(exceptionObject);
  90 #endif
  91   return objectp;
  92 }
  93
  94
  95 extern "C" void
  96 __cxxabiv1::__cxa_end_catch ()
  97 {
  98   __cxa_eh_globals *globals = __cxa_get_globals_fast ();
  99   __cxa_exception *header = globals->caughtExceptions;
 100
 101   // A rethrow of a foreign exception will be removed from the
 102   // the exception stack immediately by __cxa_rethrow.
 103   if (!header)
 104     return;
 105
 106   // A foreign exception couldn't have been stacked (see above),
 107   // so by definition processing must be complete.
 108   if (!__is_gxx_exception_class(header->unwindHeader.exception_class))
 109     {
 110       globals->caughtExceptions = 0;
 111       _Unwind_DeleteException (&header->unwindHeader);
 112       return;
 113     }
 114
 115   int count = header->handlerCount;
 116   if (count < 0)
 117     {
 118       // This exception was rethrown.  Decrement the (inverted) catch
 119       // count and remove it from the chain when it reaches zero.
 120       if (++count == 0)
 121         globals->caughtExceptions = header->nextException;
 122     }
 123   else if (--count == 0)
 124     {
 125       // Handling for this exception is complete.  Destroy the object.
 126       globals->caughtExceptions = header->nextException;
 127       _Unwind_DeleteException (&header->unwindHeader);
 128       return;
 129     }
 130   else if (count < 0)
 131     // A bug in the exception handling library or compiler.
 132     std::terminate ();
 133
 134   header->handlerCount = count;
 135 }
 136
 137
 138 bool
 139 std::uncaught_exception() throw()
 140 {
 141   __cxa_eh_globals *globals = __cxa_get_globals ();
 142   return globals->uncaughtExceptions != 0;
 143 }