gcc/libstdc++-v3/libsupc++/eh_personality.cc

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// -*- C++ -*- The GNU C++ exception personality routine.
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This file is part of GNU CC.
//
// GNU CC is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// GNU CC is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with GNU CC; see the file COPYING. If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
#include <bits/c++config.h>
#include <cstdlib>
#include <exception_defines.h>
#include "unwind-cxx.h"
using namespace __cxxabiv1;
#include "unwind-pe.h"
struct lsda_header_info
{
_Unwind_Ptr Start;
_Unwind_Ptr LPStart;
_Unwind_Ptr ttype_base;
const unsigned char *TType;
const unsigned char *action_table;
unsigned char ttype_encoding;
unsigned char call_site_encoding;
};
static const unsigned char *
parse_lsda_header (_Unwind_Context *context, const unsigned char *p,
lsda_header_info *info)
{
_Unwind_Word tmp;
unsigned char lpstart_encoding;
info->Start = (context ? _Unwind_GetRegionStart (context) : 0);
// Find @LPStart, the base to which landing pad offsets are relative.
lpstart_encoding = *p++;
if (lpstart_encoding != DW_EH_PE_omit)
p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart);
else
info->LPStart = info->Start;
// Find @TType, the base of the handler and exception spec type data.
info->ttype_encoding = *p++;
if (info->ttype_encoding != DW_EH_PE_omit)
{
p = read_uleb128 (p, &tmp);
info->TType = p + tmp;
}
else
info->TType = 0;
// The encoding and length of the call-site table; the action table
// immediately follows.
info->call_site_encoding = *p++;
p = read_uleb128 (p, &tmp);
info->action_table = p + tmp;
return p;
}
static const std::type_info *
get_ttype_entry (lsda_header_info *info, _Unwind_Word i)
{
_Unwind_Ptr ptr;
i *= size_of_encoded_value (info->ttype_encoding);
read_encoded_value_with_base (info->ttype_encoding, info->ttype_base,
info->TType - i, &ptr);
return reinterpret_cast<const std::type_info *>(ptr);
}
// Given the thrown type THROW_TYPE, pointer to a variable containing a
// pointer to the exception object THROWN_PTR_P and a type CATCH_TYPE to
// compare against, return whether or not there is a match and if so,
// update *THROWN_PTR_P.
static bool
get_adjusted_ptr (const std::type_info *catch_type,
const std::type_info *throw_type,
void **thrown_ptr_p)
{
void *thrown_ptr = *thrown_ptr_p;
// Pointer types need to adjust the actual pointer, not
// the pointer to pointer that is the exception object.
// This also has the effect of passing pointer types
// "by value" through the __cxa_begin_catch return value.
if (throw_type->__is_pointer_p ())
thrown_ptr = *(void **) thrown_ptr;
if (catch_type->__do_catch (throw_type, &thrown_ptr, 1))
{
*thrown_ptr_p = thrown_ptr;
return true;
}
return false;
}
static bool
check_exception_spec (lsda_header_info *info, const std::type_info *throw_type,
void *thrown_ptr, _Unwind_Sword filter_value)
{
const unsigned char *e = info->TType - filter_value - 1;
while (1)
{
const std::type_info *catch_type;
_Unwind_Word tmp;
e = read_uleb128 (e, &tmp);
// Zero signals the end of the list. If we've not found
// a match by now, then we've failed the specification.
if (tmp == 0)
return false;
// Match a ttype entry.
catch_type = get_ttype_entry (info, tmp);
// ??? There is currently no way to ask the RTTI code about the
// relationship between two types without reference to a specific
// object. There should be; then we wouldn't need to mess with
// thrown_ptr here.
if (get_adjusted_ptr (catch_type, throw_type, &thrown_ptr))
return true;
}
}
// Using a different personality function name causes link failures
// when trying to mix code using different exception handling models.
#ifdef _GLIBCPP_SJLJ_EXCEPTIONS
#define PERSONALITY_FUNCTION __gxx_personality_sj0
#define __builtin_eh_return_data_regno(x) x
#else
#define PERSONALITY_FUNCTION __gxx_personality_v0
#endif
extern "C" _Unwind_Reason_Code
PERSONALITY_FUNCTION (int version,
_Unwind_Action actions,
_Unwind_Exception_Class exception_class,
struct _Unwind_Exception *ue_header,
struct _Unwind_Context *context)
{
__cxa_exception *xh = __get_exception_header_from_ue (ue_header);
enum found_handler_type
{
found_nothing,
found_terminate,
found_cleanup,
found_handler
} found_type;
lsda_header_info info;
const unsigned char *language_specific_data;
const unsigned char *action_record;
const unsigned char *p;
_Unwind_Ptr landing_pad, ip;
int handler_switch_value;
void *thrown_ptr = xh + 1;
// Interface version check.
if (version != 1)
return _URC_FATAL_PHASE1_ERROR;
// Shortcut for phase 2 found handler for domestic exception.
if (actions == (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME)
&& exception_class == __gxx_exception_class)
{
handler_switch_value = xh->handlerSwitchValue;
landing_pad = (_Unwind_Ptr) xh->catchTemp;
found_type = (landing_pad == 0 ? found_terminate : found_handler);
goto install_context;
}
language_specific_data = (const unsigned char *)
_Unwind_GetLanguageSpecificData (context);
// If no LSDA, then there are no handlers or cleanups.
if (! language_specific_data)
return _URC_CONTINUE_UNWIND;
// Parse the LSDA header.
p = parse_lsda_header (context, language_specific_data, &info);
info.ttype_base = base_of_encoded_value (info.ttype_encoding, context);
ip = _Unwind_GetIP (context) - 1;
landing_pad = 0;
action_record = 0;
handler_switch_value = 0;
#ifdef _GLIBCPP_SJLJ_EXCEPTIONS
// The given "IP" is an index into the call-site table, with two
// exceptions -- -1 means no-action, and 0 means terminate. But
// since we're using uleb128 values, we've not got random access
// to the array.
if ((int) ip < 0)
return _URC_CONTINUE_UNWIND;
else if (ip == 0)
{
// Fall through to set found_terminate.
}
else
{
_Unwind_Word cs_lp, cs_action;
do
{
p = read_uleb128 (p, &cs_lp);
p = read_uleb128 (p, &cs_action);
}
while (--ip);
// Can never have null landing pad for sjlj -- that would have
// been indicated by a -1 call site index.
landing_pad = cs_lp + 1;
if (cs_action)
action_record = info.action_table + cs_action - 1;
goto found_something;
}
#else
// Search the call-site table for the action associated with this IP.
while (p < info.action_table)
{
_Unwind_Ptr cs_start, cs_len, cs_lp;
_Unwind_Word cs_action;
// Note that all call-site encodings are "absolute" displacements.
p = read_encoded_value (0, info.call_site_encoding, p, &cs_start);
p = read_encoded_value (0, info.call_site_encoding, p, &cs_len);
p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp);
p = read_uleb128 (p, &cs_action);
// The table is sorted, so if we've passed the ip, stop.
if (ip < info.Start + cs_start)
p = info.action_table;
else if (ip < info.Start + cs_start + cs_len)
{
if (cs_lp)
landing_pad = info.LPStart + cs_lp;
if (cs_action)
action_record = info.action_table + cs_action - 1;
goto found_something;
}
}
#endif // _GLIBCPP_SJLJ_EXCEPTIONS
// If ip is not present in the table, call terminate. This is for
// a destructor inside a cleanup, or a library routine the compiler
// was not expecting to throw.
found_type = (actions & _UA_FORCE_UNWIND ? found_nothing : found_terminate);
goto do_something;
found_something:
if (landing_pad == 0)
{
// If ip is present, and has a null landing pad, there are
// no cleanups or handlers to be run.
found_type = found_nothing;
}
else if (action_record == 0)
{
// If ip is present, has a non-null landing pad, and a null
// action table offset, then there are only cleanups present.
// Cleanups use a zero switch value, as set above.
found_type = found_cleanup;
}
else
{
// Otherwise we have a catch handler or exception specification.
_Unwind_Sword ar_filter, ar_disp;
const std::type_info *throw_type, *catch_type;
bool saw_cleanup = false;
bool saw_handler = false;
// During forced unwinding, we only run cleanups. With a foreign
// exception class, there's no exception type.
// ??? What to do about GNU Java and GNU Ada exceptions.
if ((actions & _UA_FORCE_UNWIND)
|| exception_class != __gxx_exception_class)
throw_type = 0;
else
throw_type = xh->exceptionType;
while (1)
{
p = action_record;
p = read_sleb128 (p, &ar_filter);
read_sleb128 (p, &ar_disp);
if (ar_filter == 0)
{
// Zero filter values are cleanups.
saw_cleanup = true;
}
else if (ar_filter > 0)
{
// Positive filter values are handlers.
catch_type = get_ttype_entry (&info, ar_filter);
// Null catch type is a catch-all handler. We can catch
// foreign exceptions with this.
if (! catch_type)
{
if (!(actions & _UA_FORCE_UNWIND))
{
saw_handler = true;
break;
}
}
else if (throw_type)
{
if (get_adjusted_ptr (catch_type, throw_type, &thrown_ptr))
{
saw_handler = true;
break;
}
}
}
else
{
// Negative filter values are exception specifications.
// ??? How do foreign exceptions fit in? As far as I can
// see we can't match because there's no __cxa_exception
// object to stuff bits in for __cxa_call_unexpected to use.
if (throw_type
&& ! check_exception_spec (&info, throw_type, thrown_ptr,
ar_filter))
{
saw_handler = true;
break;
}
}
if (ar_disp == 0)
break;
action_record = p + ar_disp;
}
if (saw_handler)
{
handler_switch_value = ar_filter;
found_type = found_handler;
}
else
found_type = (saw_cleanup ? found_cleanup : found_nothing);
}
do_something:
if (found_type == found_nothing)
return _URC_CONTINUE_UNWIND;
if (actions & _UA_SEARCH_PHASE)
{
if (found_type == found_cleanup)
return _URC_CONTINUE_UNWIND;
// For domestic exceptions, we cache data from phase 1 for phase 2.
if (exception_class == __gxx_exception_class)
{
xh->handlerSwitchValue = handler_switch_value;
xh->actionRecord = action_record;
xh->languageSpecificData = language_specific_data;
xh->adjustedPtr = thrown_ptr;
// ??? Completely unknown what this field is supposed to be for.
// ??? Need to cache TType encoding base for call_unexpected.
xh->catchTemp = (void *) (_Unwind_Ptr) landing_pad;
}
return _URC_HANDLER_FOUND;
}
install_context:
if (found_type == found_terminate)
{
__cxa_begin_catch (&xh->unwindHeader);
__terminate (xh->terminateHandler);
}
// Cache the TType base value for __cxa_call_unexpected, as we won't
// have an _Unwind_Context then.
if (handler_switch_value < 0)
{
parse_lsda_header (context, xh->languageSpecificData, &info);
xh->catchTemp = (void *) base_of_encoded_value (info.ttype_encoding,
context);
}
_Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
(_Unwind_Ptr) &xh->unwindHeader);
_Unwind_SetGR (context, __builtin_eh_return_data_regno (1),
handler_switch_value);
_Unwind_SetIP (context, landing_pad);
return _URC_INSTALL_CONTEXT;
}
extern "C" void
__cxa_call_unexpected (void *exc_obj_in)
{
_Unwind_Exception *exc_obj
= reinterpret_cast <_Unwind_Exception *>(exc_obj_in);
__cxa_begin_catch (exc_obj);
// This function is a handler for our exception argument. If we exit
// by throwing a different exception, we'll need the original cleaned up.
struct end_catch_protect
{
end_catch_protect() { }
~end_catch_protect() { __cxa_end_catch(); }
} end_catch_protect_obj;
lsda_header_info info;
__cxa_exception *xh = __get_exception_header_from_ue (exc_obj);
const unsigned char *xh_lsda;
_Unwind_Sword xh_switch_value;
std::terminate_handler xh_terminate_handler;
// If the unexpectedHandler rethrows the exception (e.g. to categorize it),
// it will clobber data about the current handler. So copy the data out now.
xh_lsda = xh->languageSpecificData;
xh_switch_value = xh->handlerSwitchValue;
xh_terminate_handler = xh->terminateHandler;
info.ttype_base = (_Unwind_Ptr) xh->catchTemp;
try
{ __unexpected (xh->unexpectedHandler); }
catch(...)
{
// Get the exception thrown from unexpected.
// ??? Foreign exceptions can't be stacked this way.
__cxa_eh_globals *globals = __cxa_get_globals_fast ();
__cxa_exception *new_xh = globals->caughtExceptions;
void *new_ptr = new_xh + 1;
// We don't quite have enough stuff cached; re-parse the LSDA.
parse_lsda_header (0, xh_lsda, &info);
// If this new exception meets the exception spec, allow it.
if (check_exception_spec (&info, new_xh->exceptionType,
new_ptr, xh_switch_value))
__throw_exception_again;
// If the exception spec allows std::bad_exception, throw that.
// We don't have a thrown object to compare against, but since
// bad_exception doesn't have virtual bases, that's OK; just pass 0.
#ifdef __EXCEPTIONS
const std::type_info &bad_exc = typeid (std::bad_exception);
if (check_exception_spec (&info, &bad_exc, 0, xh_switch_value))
throw std::bad_exception();
#endif
// Otherwise, die.
__terminate (xh_terminate_handler);
}
}