377 lines
11 KiB
C
377 lines
11 KiB
C
/* The implementation of exception handling primitives for Objective-C.
|
||
Copyright (C) 2004 Free Software Foundation, Inc.
|
||
|
||
This file is part of GCC.
|
||
|
||
GCC 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.
|
||
|
||
GCC 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 GCC; see the file COPYING. If not, write to
|
||
the Free Software Foundation, 51 Franklin Street, Fifth Floor,
|
||
Boston, MA 02110-1301, USA. */
|
||
|
||
/* As a special exception, if you link this library with files compiled
|
||
with GCC to produce an executable, this does not 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 <stdlib.h>
|
||
#include "config.h"
|
||
#include "objc/objc-api.h"
|
||
#include "unwind.h"
|
||
#include "unwind-pe.h"
|
||
|
||
|
||
/* This is the exception class we report -- "GNUCOBJC". */
|
||
#define __objc_exception_class \
|
||
((((((((_Unwind_Exception_Class) 'G' \
|
||
<< 8 | (_Unwind_Exception_Class) 'N') \
|
||
<< 8 | (_Unwind_Exception_Class) 'U') \
|
||
<< 8 | (_Unwind_Exception_Class) 'C') \
|
||
<< 8 | (_Unwind_Exception_Class) 'O') \
|
||
<< 8 | (_Unwind_Exception_Class) 'B') \
|
||
<< 8 | (_Unwind_Exception_Class) 'J') \
|
||
<< 8 | (_Unwind_Exception_Class) 'C')
|
||
|
||
/* This is the object that is passed around by the Objective C runtime
|
||
to represent the exception in flight. */
|
||
|
||
struct ObjcException
|
||
{
|
||
/* This bit is needed in order to interact with the unwind runtime. */
|
||
struct _Unwind_Exception base;
|
||
|
||
/* The actual object we want to throw. */
|
||
id value;
|
||
|
||
/* Cache some internal unwind data between phase 1 and phase 2. */
|
||
_Unwind_Ptr landingPad;
|
||
int handlerSwitchValue;
|
||
};
|
||
|
||
|
||
|
||
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 (struct _Unwind_Context *context, const unsigned char *p,
|
||
struct 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 Class
|
||
get_ttype_entry (struct 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);
|
||
|
||
/* NULL ptr means catch-all. */
|
||
if (ptr)
|
||
return objc_get_class ((const char *) ptr);
|
||
else
|
||
return 0;
|
||
}
|
||
|
||
/* Like unto the method of the same name on Object, but takes an id. */
|
||
/* ??? Does this bork the meta-type system? Can/should we look up an
|
||
isKindOf method on the id? */
|
||
|
||
static int
|
||
isKindOf (id value, Class target)
|
||
{
|
||
Class c;
|
||
|
||
/* NULL target is catch-all. */
|
||
if (target == 0)
|
||
return 1;
|
||
|
||
for (c = value->class_pointer; c; c = class_get_super_class (c))
|
||
if (c == target)
|
||
return 1;
|
||
return 0;
|
||
}
|
||
|
||
/* Using a different personality function name causes link failures
|
||
when trying to mix code using different exception handling models. */
|
||
#ifdef SJLJ_EXCEPTIONS
|
||
#define PERSONALITY_FUNCTION __gnu_objc_personality_sj0
|
||
#define __builtin_eh_return_data_regno(x) x
|
||
#else
|
||
#define PERSONALITY_FUNCTION __gnu_objc_personality_v0
|
||
#endif
|
||
|
||
_Unwind_Reason_Code
|
||
PERSONALITY_FUNCTION (int version,
|
||
_Unwind_Action actions,
|
||
_Unwind_Exception_Class exception_class,
|
||
struct _Unwind_Exception *ue_header,
|
||
struct _Unwind_Context *context)
|
||
{
|
||
struct ObjcException *xh = (struct ObjcException *) ue_header;
|
||
|
||
struct 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;
|
||
int saw_cleanup = 0, saw_handler;
|
||
void *return_object;
|
||
|
||
/* 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 == __objc_exception_class)
|
||
{
|
||
handler_switch_value = xh->handlerSwitchValue;
|
||
landing_pad = xh->landingPad;
|
||
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 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
|
||
{
|
||
_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 /* SJLJ_EXCEPTIONS */
|
||
|
||
/* If ip is not present in the table, C++ would call terminate. */
|
||
/* ??? As with Java, it's perhaps better to tweek the LSDA to
|
||
that no-action is mapped to no-entry. */
|
||
return _URC_CONTINUE_UNWIND;
|
||
|
||
found_something:
|
||
saw_cleanup = 0;
|
||
saw_handler = 0;
|
||
|
||
if (landing_pad == 0)
|
||
{
|
||
/* If ip is present, and has a null landing pad, there are
|
||
no cleanups or handlers to be run. */
|
||
}
|
||
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. */
|
||
saw_cleanup = 1;
|
||
}
|
||
else
|
||
{
|
||
/* Otherwise we have a catch handler. */
|
||
_Unwind_Sword ar_filter, ar_disp;
|
||
|
||
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 = 1;
|
||
}
|
||
|
||
/* During forced unwinding, we only run cleanups. With a
|
||
foreign exception class, we have no class info to match. */
|
||
else if ((actions & _UA_FORCE_UNWIND)
|
||
|| exception_class != __objc_exception_class)
|
||
;
|
||
|
||
else if (ar_filter > 0)
|
||
{
|
||
/* Positive filter values are handlers. */
|
||
|
||
Class catch_type = get_ttype_entry (&info, ar_filter);
|
||
|
||
if (isKindOf (xh->value, catch_type))
|
||
{
|
||
handler_switch_value = ar_filter;
|
||
saw_handler = 1;
|
||
break;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* Negative filter values are exception specifications,
|
||
which Objective-C does not use. */
|
||
abort ();
|
||
}
|
||
|
||
if (ar_disp == 0)
|
||
break;
|
||
action_record = p + ar_disp;
|
||
}
|
||
}
|
||
|
||
if (! saw_handler && ! saw_cleanup)
|
||
return _URC_CONTINUE_UNWIND;
|
||
|
||
if (actions & _UA_SEARCH_PHASE)
|
||
{
|
||
if (!saw_handler)
|
||
return _URC_CONTINUE_UNWIND;
|
||
|
||
/* For domestic exceptions, we cache data from phase 1 for phase 2. */
|
||
if (exception_class == __objc_exception_class)
|
||
{
|
||
xh->handlerSwitchValue = handler_switch_value;
|
||
xh->landingPad = landing_pad;
|
||
}
|
||
return _URC_HANDLER_FOUND;
|
||
}
|
||
|
||
install_context:
|
||
if (saw_cleanup == 0)
|
||
{
|
||
return_object = xh->value;
|
||
if (!(actions & _UA_SEARCH_PHASE))
|
||
_Unwind_DeleteException(&xh->base);
|
||
}
|
||
|
||
_Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
|
||
__builtin_extend_pointer (saw_cleanup ? xh : return_object));
|
||
_Unwind_SetGR (context, __builtin_eh_return_data_regno (1),
|
||
handler_switch_value);
|
||
_Unwind_SetIP (context, landing_pad);
|
||
return _URC_INSTALL_CONTEXT;
|
||
}
|
||
|
||
static void
|
||
__objc_exception_cleanup (_Unwind_Reason_Code code __attribute__((unused)),
|
||
struct _Unwind_Exception *exc)
|
||
{
|
||
free (exc);
|
||
}
|
||
|
||
void
|
||
objc_exception_throw (id value)
|
||
{
|
||
struct ObjcException *header = calloc (1, sizeof (*header));
|
||
header->base.exception_class = __objc_exception_class;
|
||
header->base.exception_cleanup = __objc_exception_cleanup;
|
||
header->value = value;
|
||
|
||
#ifdef SJLJ_EXCEPTIONS
|
||
_Unwind_SjLj_RaiseException (&header->base);
|
||
#else
|
||
_Unwind_RaiseException (&header->base);
|
||
#endif
|
||
|
||
/* Some sort of unwinding error. */
|
||
abort ();
|
||
}
|