/* The implementation of exception handling primitives for Objective-C.   Copyright (C) 2004-2026 Free Software Foundation, Inc. This file is part of GCC. GCC is free software; you can redistribute it and/or modify itunder the terms of the GNU General Public License as published by theFree Software Foundation; either version 3, or (at your option) anylater version. GCC is distributed in the hope that it will be useful, but WITHOUTANY WARRANTY; without even the implied warranty of MERCHANTABILITY orFITNESS FOR A PARTICULAR PURPOSE.  See the GNU General PublicLicense for more details. Under Section 7 of GPL version 3, you are granted additionalpermissions described in the GCC Runtime Library Exception, version3.1, as published by the Free Software Foundation. You should have received a copy of the GNU General Public License anda copy of the GCC Runtime Library Exception along with this program;see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see<http://www.gnu.org/licenses/>.  */ #include "objc-private/common.h"#include <stdlib.h>#include "config.h"#include "objc/runtime.h"#include "objc/objc-exception.h"#include "unwind.h"#include "unwind-pe.h"#include <string.h> /* For memcpy */ /* 'is_kind_of_exception_matcher' is our default exception matcher -   it determines if the object 'exception' is of class 'catch_class',   or of a subclass.  */static intis_kind_of_exception_matcher (Class catch_class, id exception){  /* NULL catch_class is catch-all (eg, @catch (id object)).  */  if (catch_class == Nil)    return 1;   /* If exception is nil (eg, @throw nil;), then it can only be     caught by a catch-all (eg, @catch (id object)).  */  if (exception != nil)    {      Class c;       for (c = exception->class_pointer; c != Nil; 	   c = class_getSuperclass (c))	if (c == catch_class)	  return 1;    }  return 0;} /* The exception matcher currently in use.  */static objc_exception_matcher__objc_exception_matcher = is_kind_of_exception_matcher; objc_exception_matcherobjc_setExceptionMatcher (objc_exception_matcher new_matcher){  objc_exception_matcher old_matcher = __objc_exception_matcher;  __objc_exception_matcher = new_matcher;  return old_matcher;} /* The uncaught exception handler currently in use.  */static objc_uncaught_exception_handler__objc_uncaught_exception_handler = NULL; objc_uncaught_exception_handlerobjc_setUncaughtExceptionHandler (objc_uncaught_exception_handler 				  new_handler){  objc_uncaught_exception_handler old_handler     = __objc_uncaught_exception_handler;  __objc_uncaught_exception_handler = new_handler;  return old_handler;}  #ifdef __ARM_EABI_UNWINDER__ const _Unwind_Exception_Class __objc_exception_class  = {'G', 'N', 'U', 'C', 'O', 'B', 'J', 'C'};  #else /* This is the exception class we report -- "GNUCOBJC".  */static const _Unwind_Exception_Class __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'); #endif /* 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. Note: must come immediately     after unwind header.  */  id value; #ifdef __ARM_EABI_UNWINDER__  /* Note: we use the barrier cache defined in the unwind control     block for ARM EABI.  */#else  /* Cache some internal unwind data between phase 1 and phase 2.  */  _Unwind_Ptr landingPad;  int handlerSwitchValue;#endif};  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){  _uleb128_t 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)    {#if _GLIBCXX_OVERRIDE_TTYPE_ENCODING      /* Older ARM EABI toolchains set this value incorrectly, so use a	 hardcoded OS-specific format.  */      info->ttype_encoding = _GLIBCXX_OVERRIDE_TTYPE_ENCODING;#endif      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 Classget_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.  Note that if the class is not found,     this will abort the program.  */  if (ptr)    return objc_getRequiredClass ((const char *) ptr);  else    return 0;} /* Using a different personality function name causes link failures   when trying to mix code using different exception handling   models.  */#ifdef __USING_SJLJ_EXCEPTIONS__#define PERSONALITY_FUNCTION	__gnu_objc_personality_sj0#define __builtin_eh_return_data_regno(x) x#elif defined(__SEH__) #define PERSONALITY_FUNCTION	__gnu_objc_personality_imp#else#define PERSONALITY_FUNCTION	__gnu_objc_personality_v0#endif #ifdef __ARM_EABI_UNWINDER__ #define CONTINUE_UNWINDING \  do								\    {								\      if (__gnu_unwind_frame(ue_header, context) != _URC_OK)	\	return _URC_FAILURE;					\      return _URC_CONTINUE_UNWIND;				\    }								\  while (0) _Unwind_Reason_Code__attribute__((target ("general-regs-only")))PERSONALITY_FUNCTION (_Unwind_State state,		      struct _Unwind_Exception *ue_header,		      struct _Unwind_Context *context)#else #define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND #if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__)static#endif_Unwind_Reason_CodePERSONALITY_FUNCTION (int version,		      _Unwind_Action actions,		      _Unwind_Exception_Class exception_class,		      struct _Unwind_Exception *ue_header,		      struct _Unwind_Context *context)#endif{  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, foreign_exception;  void *return_object;  int ip_before_insn = 0; #ifdef __ARM_EABI_UNWINDER__  _Unwind_Action actions;    switch (state & _US_ACTION_MASK)    {    case _US_VIRTUAL_UNWIND_FRAME:      actions = _UA_SEARCH_PHASE;      break;     case _US_UNWIND_FRAME_STARTING:      actions = _UA_CLEANUP_PHASE;      if (!(state & _US_FORCE_UNWIND)	  && ue_header->barrier_cache.sp == _Unwind_GetGR (context, 13))	actions |= _UA_HANDLER_FRAME;      break;     case _US_UNWIND_FRAME_RESUME:      CONTINUE_UNWINDING;      break;     default:      abort();    }  actions |= state & _US_FORCE_UNWIND;   /* TODO: Foreign exceptions need some attention (e.g. rethrowing     doesn't work).  */  foreign_exception = 0;   /* The dwarf unwinder assumes the context structure holds things     like the function and LSDA pointers.  The ARM implementation     caches these in the exception header (UCB).  To avoid rewriting     everything we make the virtual IP register point at the UCB.  */  ip = (_Unwind_Ptr) ue_header;  _Unwind_SetGR (context, 12, ip); #else  /* !__ARM_EABI_UNWINDER.  */  /* Interface version check.  */  if (version != 1)    return _URC_FATAL_PHASE1_ERROR;    foreign_exception = (exception_class != __objc_exception_class);#endif   /* Shortcut for phase 2 found handler for domestic exception.  */  if (actions == (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME)      && !foreign_exception)    {#ifdef __ARM_EABI_UNWINDER__      handler_switch_value = (int) ue_header->barrier_cache.bitpattern[1];      landing_pad = (_Unwind_Ptr) ue_header->barrier_cache.bitpattern[3];#else      handler_switch_value = xh->handlerSwitchValue;      landing_pad = xh->landingPad;#endif      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)    CONTINUE_UNWINDING;   /* Parse the LSDA header.  */  p = parse_lsda_header (context, language_specific_data, &info);  info.ttype_base = base_of_encoded_value (info.ttype_encoding, context);#ifdef HAVE_GETIPINFO  ip = _Unwind_GetIPInfo (context, &ip_before_insn);#else  ip = _Unwind_GetIP (context);#endif  if (!ip_before_insn)    --ip;  landing_pad = 0;  action_record = 0;  handler_switch_value = 0; #ifdef __USING_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    {      _uleb128_t 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;      _uleb128_t 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 /* __USING_SJLJ_EXCEPTIONS__  */   /* If ip is not present in the table, C++ would call terminate.  */  /* ??? As with Java, it's perhaps better to tweak the LSDA to that     no-action is mapped to no-entry.  */  CONTINUE_UNWINDING;  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.  */      _sleb128_t 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) || foreign_exception)	    ; 	  else if (ar_filter > 0)	    {	      /* Positive filter values are handlers.  */	      Class catch_type = get_ttype_entry (&info, ar_filter); 	      if ((*__objc_exception_matcher) (catch_type, xh->value))		{		  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)    CONTINUE_UNWINDING;   if (actions & _UA_SEARCH_PHASE)    {      if (!saw_handler)	CONTINUE_UNWINDING;       /* For domestic exceptions, we cache data from phase 1 for phase	 2.  */      if (!foreign_exception)        {#ifdef __ARM_EABI_UNWINDER__	  ue_header->barrier_cache.sp = _Unwind_GetGR (context, 13);	  ue_header->barrier_cache.bitpattern[1] = (_uw) handler_switch_value;	  ue_header->barrier_cache.bitpattern[3] = (_uw) landing_pad;#else          xh->handlerSwitchValue = handler_switch_value;          xh->landingPad = landing_pad;#endif	}      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);}

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