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