dlls/msvcrt/cppexcept.c

   1 /*
   2  * msvcrt C++ exception handling
   3  *
   4  * Copyright 2002 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library 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 GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  *
  20  * NOTES
  21  * A good reference is the article "How a C++ compiler implements
  22  * exception handling" by Vishal Kochhar, available on
  23  * www.thecodeproject.com.
  24  */
  25
  26 #include "config.h"
  27 #include "wine/port.h"
  28
  29 #include <stdarg.h>
  30
  31 #include "windef.h"
  32 #include "winbase.h"
  33 #include "winreg.h"
  34 #include "winternl.h"
  35 #include "msvcrt.h"
  36 #include "wine/exception.h"
  37 #include "excpt.h"
  38 #include "wine/debug.h"
  39
  40 #include "cppexcept.h"
  41
  42 WINE_DEFAULT_DEBUG_CHANNEL(seh);
  43
  44 #ifdef __i386__  /* CxxFrameHandler is not supported on non-i386 */
  45
  46 static DWORD cxx_frame_handler( PEXCEPTION_RECORD rec, cxx_exception_frame* frame,
  47                                 PCONTEXT exc_context, EXCEPTION_REGISTRATION_RECORD** dispatch,
  48                                 cxx_function_descr *descr, EXCEPTION_REGISTRATION_RECORD* nested_frame,
  49                                 int nested_trylevel, CONTEXT86 *context );
  50
  51 /* call a function with a given ebp */
  52 inline static void *call_ebp_func( void *func, void *ebp )
  53 {
  54     void *ret;
  55     __asm__ __volatile__ ("pushl %%ebp; movl %2,%%ebp; call *%%eax; popl %%ebp" \
  56                           : "=a" (ret) : "0" (func), "g" (ebp) : "ecx", "edx", "memory" );
  57     return ret;
  58 }
  59
  60 /* call a copy constructor */
  61 inline static void call_copy_ctor( void *func, void *this, void *src, int has_vbase )
  62 {
  63     TRACE( "calling copy ctor %p object %p src %p\n", func, this, src );
  64     if (has_vbase)
  65         /* in that case copy ctor takes an extra bool indicating whether to copy the base class */
  66         __asm__ __volatile__("pushl $1; pushl %2; call *%0"
  67                              : : "r" (func), "c" (this), "g" (src) : "eax", "edx", "memory" );
  68     else
  69         __asm__ __volatile__("pushl %2; call *%0"
  70                              : : "r" (func), "c" (this), "g" (src) : "eax", "edx", "memory" );
  71 }
  72
  73 /* call the destructor of the exception object */
  74 inline static void call_dtor( void *func, void *object )
  75 {
  76     __asm__ __volatile__("call *%0" : : "r" (func), "c" (object) : "eax", "edx", "memory" );
  77 }
  78
  79 static void dump_type( const cxx_type_info *type )
  80 {
  81     DPRINTF( "flags %x type %p", type->flags, type->type_info );
  82     if (type->type_info) DPRINTF( " (%p %s)", type->type_info->name, type->type_info->mangled );
  83     DPRINTF( " offset %d vbase %d,%d size %d copy ctor %p\n", type->this_offset,
  84              type->vbase_descr, type->vbase_offset, type->size, type->copy_ctor );
  85 }
  86
  87 static void dump_exception_type( const cxx_exception_type *type )
  88 {
  89     UINT i;
  90
  91     DPRINTF( "exception type:\n" );
  92     DPRINTF( "flags %x destr %p handler %p type info %p\n",
  93              type->flags, type->destructor, type->custom_handler, type->type_info_table );
  94     for (i = 0; i < type->type_info_table->count; i++)
  95     {
  96         DPRINTF( "    %d: ", i );
  97         dump_type( type->type_info_table->info[i] );
  98     }
  99 }
 100
 101 static void dump_function_descr( const cxx_function_descr *descr, const cxx_exception_type *info )
 102 {
 103     UINT i;
 104     int j;
 105
 106     DPRINTF( "function descr:\n" );
 107     DPRINTF( "magic %x\n", descr->magic );
 108     DPRINTF( "unwind table: %p %d\n", descr->unwind_table, descr->unwind_count );
 109     for (i = 0; i < descr->unwind_count; i++)
 110     {
 111         DPRINTF( "    %d: prev %d func %p\n", i,
 112                  descr->unwind_table[i].prev, descr->unwind_table[i].handler );
 113     }
 114     DPRINTF( "try table: %p %d\n", descr->tryblock, descr->tryblock_count );
 115     for (i = 0; i < descr->tryblock_count; i++)
 116     {
 117         DPRINTF( "    %d: start %d end %d catchlevel %d catch %p %d\n", i,
 118                  descr->tryblock[i].start_level, descr->tryblock[i].end_level,
 119                  descr->tryblock[i].catch_level, descr->tryblock[i].catchblock,
 120                  descr->tryblock[i].catchblock_count );
 121         for (j = 0; j < descr->tryblock[i].catchblock_count; j++)
 122         {
 123             catchblock_info *ptr = &descr->tryblock[i].catchblock[j];
 124             DPRINTF( "        %d: flags %x offset %d handler %p type %p",
 125                      j, ptr->flags, ptr->offset, ptr->handler, ptr->type_info );
 126             if (ptr->type_info) DPRINTF( " (%p %s)", ptr->type_info->name, ptr->type_info->mangled );
 127             DPRINTF( "\n" );
 128         }
 129     }
 130 }
 131
 132 /* compute the this pointer for a base class of a given type */
 133 static void *get_this_pointer( const cxx_type_info *type, void *object )
 134 {
 135     void *this_ptr;
 136     int *offset_ptr;
 137
 138     if (!object) return NULL;
 139     this_ptr = (char *)object + type->this_offset;
 140     if (type->vbase_descr >= 0)
 141     {
 142         /* move this ptr to vbase descriptor */
 143         this_ptr = (char *)this_ptr + type->vbase_descr;
 144         /* and fetch additional offset from vbase descriptor */
 145         offset_ptr = (int *)(*(char **)this_ptr + type->vbase_offset);
 146         this_ptr = (char *)this_ptr + *offset_ptr;
 147     }
 148     return this_ptr;
 149 }
 150
 151 /* check if the exception type is caught by a given catch block, and return the type that matched */
 152 static const cxx_type_info *find_caught_type( cxx_exception_type *exc_type, catchblock_info *catchblock )
 153 {
 154     UINT i;
 155
 156     for (i = 0; i < exc_type->type_info_table->count; i++)
 157     {
 158         const cxx_type_info *type = exc_type->type_info_table->info[i];
 159
 160         if (!catchblock->type_info) return type;   /* catch(...) matches any type */
 161         if (catchblock->type_info != type->type_info)
 162         {
 163             if (strcmp( catchblock->type_info->mangled, type->type_info->mangled )) continue;
 164         }
 165         /* type is the same, now check the flags */
 166         if ((exc_type->flags & TYPE_FLAG_CONST) &&
 167             !(catchblock->flags & TYPE_FLAG_CONST)) continue;
 168         if ((exc_type->flags & TYPE_FLAG_VOLATILE) &&
 169             !(catchblock->flags & TYPE_FLAG_VOLATILE)) continue;
 170         return type;  /* it matched */
 171     }
 172     return NULL;
 173 }
 174
 175
 176 /* copy the exception object where the catch block wants it */
 177 static void copy_exception( void *object, cxx_exception_frame *frame,
 178                             catchblock_info *catchblock, const cxx_type_info *type )
 179 {
 180     void **dest_ptr;
 181
 182     if (!catchblock->type_info || !catchblock->type_info->mangled[0]) return;
 183     if (!catchblock->offset) return;
 184     dest_ptr = (void **)((char *)&frame->ebp + catchblock->offset);
 185
 186     if (catchblock->flags & TYPE_FLAG_REFERENCE)
 187     {
 188         *dest_ptr = get_this_pointer( type, object );
 189     }
 190     else if (type->flags & CLASS_IS_SIMPLE_TYPE)
 191     {
 192         memmove( dest_ptr, object, type->size );
 193         /* if it is a pointer, adjust it */
 194         if (type->size == sizeof(void *)) *dest_ptr = get_this_pointer( type, *dest_ptr );
 195     }
 196     else  /* copy the object */
 197     {
 198         if (type->copy_ctor)
 199             call_copy_ctor( type->copy_ctor, dest_ptr, get_this_pointer(type,object),
 200                             (type->flags & CLASS_HAS_VIRTUAL_BASE_CLASS) );
 201         else
 202             memmove( dest_ptr, get_this_pointer(type,object), type->size );
 203     }
 204 }
 205
 206 /* unwind the local function up to a given trylevel */
 207 static void cxx_local_unwind( cxx_exception_frame* frame, cxx_function_descr *descr, int last_level)
 208 {
 209     void (*handler)();
 210     int trylevel = frame->trylevel;
 211
 212     while (trylevel != last_level)
 213     {
 214         if (trylevel < 0 || trylevel >= descr->unwind_count)
 215         {
 216             ERR( "invalid trylevel %d\n", trylevel );
 217             MSVCRT_terminate();
 218         }
 219         handler = descr->unwind_table[trylevel].handler;
 220         if (handler)
 221         {
 222             TRACE( "calling unwind handler %p trylevel %d last %d ebp %p\n",
 223                    handler, trylevel, last_level, &frame->ebp );
 224             call_ebp_func( handler, &frame->ebp );
 225         }
 226         trylevel = descr->unwind_table[trylevel].prev;
 227     }
 228     frame->trylevel = last_level;
 229 }
 230
 231 /* exception frame for nested exceptions in catch block */
 232 struct catch_func_nested_frame
 233 {
 234     EXCEPTION_REGISTRATION_RECORD frame;     /* standard exception frame */
 235     EXCEPTION_RECORD             *prev_rec;  /* previous record to restore in thread data */
 236     cxx_exception_frame          *cxx_frame; /* frame of parent exception */
 237     cxx_function_descr           *descr;     /* descriptor of parent exception */
 238     int                           trylevel;  /* current try level */
 239 };
 240
 241 /* handler for exceptions happening while calling a catch function */
 242 static DWORD catch_function_nested_handler( EXCEPTION_RECORD *rec, EXCEPTION_REGISTRATION_RECORD *frame,
 243                                             CONTEXT *context, EXCEPTION_REGISTRATION_RECORD **dispatcher )
 244 {
 245     struct catch_func_nested_frame *nested_frame = (struct catch_func_nested_frame *)frame;
 246
 247     if (rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND))
 248     {
 249         msvcrt_get_thread_data()->exc_record = nested_frame->prev_rec;
 250         return ExceptionContinueSearch;
 251     }
 252     else
 253     {
 254         TRACE( "got nested exception in catch function\n" );
 255         return cxx_frame_handler( rec, nested_frame->cxx_frame, context,
 256                                   NULL, nested_frame->descr, &nested_frame->frame,
 257                                   nested_frame->trylevel, context );
 258     }
 259 }
 260
 261 /* find and call the appropriate catch block for an exception */
 262 /* returns the address to continue execution to after the catch block was called */
 263 inline static void *call_catch_block( PEXCEPTION_RECORD rec, cxx_exception_frame *frame,
 264                                       cxx_function_descr *descr, int nested_trylevel,
 265                                       cxx_exception_type *info )
 266 {
 267     UINT i;
 268     int j;
 269     void *addr, *object = (void *)rec->ExceptionInformation[1];
 270     struct catch_func_nested_frame nested_frame;
 271     int trylevel = frame->trylevel;
 272     thread_data_t *thread_data = msvcrt_get_thread_data();
 273
 274     for (i = 0; i < descr->tryblock_count; i++)
 275     {
 276         tryblock_info *tryblock = &descr->tryblock[i];
 277
 278         if (trylevel < tryblock->start_level) continue;
 279         if (trylevel > tryblock->end_level) continue;
 280
 281         /* got a try block */
 282         for (j = 0; j < tryblock->catchblock_count; j++)
 283         {
 284             catchblock_info *catchblock = &tryblock->catchblock[j];
 285             const cxx_type_info *type = find_caught_type( info, catchblock );
 286             if (!type) continue;
 287
 288             TRACE( "matched type %p in tryblock %d catchblock %d\n", type, i, j );
 289
 290             /* copy the exception to its destination on the stack */
 291             copy_exception( object, frame, catchblock, type );
 292
 293             /* unwind the stack */
 294             RtlUnwind( frame, 0, rec, 0 );
 295             cxx_local_unwind( frame, descr, tryblock->start_level );
 296             frame->trylevel = tryblock->end_level + 1;
 297
 298             /* call the catch block */
 299             TRACE( "calling catch block %p for type %p addr %p ebp %p\n",
 300                    catchblock, type, catchblock->handler, &frame->ebp );
 301
 302             /* setup an exception block for nested exceptions */
 303
 304             nested_frame.frame.Handler = catch_function_nested_handler;
 305             nested_frame.prev_rec  = thread_data->exc_record;
 306             nested_frame.cxx_frame = frame;
 307             nested_frame.descr     = descr;
 308             nested_frame.trylevel  = nested_trylevel + 1;
 309
 310             __wine_push_frame( &nested_frame.frame );
 311             thread_data->exc_record = rec;
 312             addr = call_ebp_func( catchblock->handler, &frame->ebp );
 313             thread_data->exc_record = nested_frame.prev_rec;
 314             __wine_pop_frame( &nested_frame.frame );
 315
 316             if (info->destructor) call_dtor( info->destructor, object );
 317             TRACE( "done, continuing at %p\n", addr );
 318             return addr;
 319         }
 320     }
 321     return NULL;
 322 }
 323
 324
 325 /*********************************************************************
 326  *              cxx_frame_handler
 327  *
 328  * Implementation of __CxxFrameHandler.
 329  */
 330 static DWORD cxx_frame_handler( PEXCEPTION_RECORD rec, cxx_exception_frame* frame,
 331                                 PCONTEXT exc_context, EXCEPTION_REGISTRATION_RECORD** dispatch,
 332                                 cxx_function_descr *descr, EXCEPTION_REGISTRATION_RECORD* nested_frame,
 333                                 int nested_trylevel, CONTEXT86 *context )
 334 {
 335     cxx_exception_type *exc_type;
 336     void *next_ip;
 337
 338     if (descr->magic != CXX_FRAME_MAGIC)
 339     {
 340         ERR( "invalid frame magic %x\n", descr->magic );
 341         return ExceptionContinueSearch;
 342     }
 343     if (rec->ExceptionFlags & (EH_UNWINDING|EH_EXIT_UNWIND))
 344     {
 345         if (descr->unwind_count && !nested_trylevel) cxx_local_unwind( frame, descr, -1 );
 346         return ExceptionContinueSearch;
 347     }
 348     if (!descr->tryblock_count) return ExceptionContinueSearch;
 349
 350     exc_type = (cxx_exception_type *)rec->ExceptionInformation[2];
 351     if (rec->ExceptionCode == CXX_EXCEPTION &&
 352         rec->ExceptionInformation[0] > CXX_FRAME_MAGIC &&
 353         exc_type->custom_handler)
 354     {
 355         return exc_type->custom_handler( rec, frame, exc_context, dispatch,
 356                                          descr, nested_trylevel, nested_frame, 0 );
 357     }
 358
 359     if (!exc_type)  /* nested exception, fetch info from original exception */
 360     {
 361         rec = msvcrt_get_thread_data()->exc_record;
 362         exc_type = (cxx_exception_type *)rec->ExceptionInformation[2];
 363     }
 364
 365     if (TRACE_ON(seh))
 366     {
 367         TRACE("handling C++ exception rec %p frame %p trylevel %d descr %p nested_frame %p\n",
 368               rec, frame, frame->trylevel, descr, nested_frame );
 369         dump_exception_type( exc_type );
 370         dump_function_descr( descr, exc_type );
 371     }
 372
 373     next_ip = call_catch_block( rec, frame, descr, frame->trylevel, exc_type );
 374
 375     if (!next_ip) return ExceptionContinueSearch;
 376     rec->ExceptionFlags &= ~EH_NONCONTINUABLE;
 377     context->Eip = (DWORD)next_ip;
 378     context->Ebp = (DWORD)&frame->ebp;
 379     context->Esp = ((DWORD*)frame)[-1];
 380     return ExceptionContinueExecution;
 381 }
 382
 383
 384 /*********************************************************************
 385  *              __CxxFrameHandler (MSVCRT.@)
 386  */
 387 void MSVCRT__CxxFrameHandler( PEXCEPTION_RECORD rec, EXCEPTION_REGISTRATION_RECORD* frame,
 388                               PCONTEXT exc_context, EXCEPTION_REGISTRATION_RECORD** dispatch,
 389                               CONTEXT86 *context )
 390 {
 391     cxx_function_descr *descr = (cxx_function_descr *)context->Eax;
 392     context->Eax = cxx_frame_handler( rec, (cxx_exception_frame *)frame,
 393                                       exc_context, dispatch, descr, NULL, 0, context );
 394 }
 395 DEFINE_REGS_ENTRYPOINT( __CxxFrameHandler, MSVCRT__CxxFrameHandler, 16, 0 );
 396
 397 #endif  /* __i386__ */
 398
 399 /*********************************************************************
 400  *              _CxxThrowException (MSVCRT.@)
 401  */
 402 void _CxxThrowException( void *object, const cxx_exception_type *type )
 403 {
 404     DWORD args[3];
 405
 406     args[0] = CXX_FRAME_MAGIC;
 407     args[1] = (DWORD)object;
 408     args[2] = (DWORD)type;
 409     RaiseException( CXX_EXCEPTION, EH_NONCONTINUABLE, 3, args );
 410 }
 411
 412 /*********************************************************************
 413  *              __CxxDetectRethrow (MSVCRT.@)
 414  */
 415 BOOL __CxxDetectRethrow(PEXCEPTION_POINTERS ptrs)
 416 {
 417   PEXCEPTION_RECORD rec;
 418
 419   if (!ptrs)
 420     return FALSE;
 421
 422   rec = ptrs->ExceptionRecord;
 423
 424   if (rec->ExceptionCode == CXX_EXCEPTION &&
 425       rec->NumberParameters == 3 &&
 426       rec->ExceptionInformation[0] == CXX_FRAME_MAGIC &&
 427       rec->ExceptionInformation[2])
 428   {
 429     ptrs->ExceptionRecord = msvcrt_get_thread_data()->exc_record;
 430     return TRUE;
 431   }
 432   return (msvcrt_get_thread_data()->exc_record == rec);
 433 }
 434
 435 /*********************************************************************
 436  *              __CxxQueryExceptionSize (MSVCRT.@)
 437  */
 438 unsigned int __CxxQueryExceptionSize(void)
 439 {
 440   return sizeof(cxx_exception_type);
 441 }