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 "msvcrt/excpt.h"
  33 #include "wine/debug.h"
  34
  35 WINE_DEFAULT_DEBUG_CHANNEL(seh);
  36
  37 #define CXX_FRAME_MAGIC    0x19930520
  38 #define CXX_EXCEPTION      0xe06d7363
  39
  40 typedef struct __type_info
  41 {
  42   void *vtable;
  43   void *data;
  44   char name[1];
  45 } type_info;
  46
  47 /* the exception frame used by CxxFrameHandler */
  48 typedef struct __cxx_exception_frame
  49 {
  50     EXCEPTION_FRAME  frame;    /* the standard exception frame */
  51     int              trylevel;
  52     DWORD            ebp;
  53 } cxx_exception_frame;
  54
  55 /* info about a single catch {} block */
  56 typedef struct __catchblock_info
  57 {
  58     UINT       flags;         /* flags (see below) */
  59     type_info *type_info;     /* C++ type caught by this block */
  60     int        offset;        /* stack offset to copy exception object to */
  61     void     (*handler)();    /* catch block handler code */
  62 } catchblock_info;
  63 #define TYPE_FLAG_CONST      1
  64 #define TYPE_FLAG_VOLATILE   2
  65 #define TYPE_FLAG_REFERENCE  8
  66
  67 /* info about a single try {} block */
  68 typedef struct __tryblock_info
  69 {
  70     int              start_level;      /* start trylevel of that block */
  71     int              end_level;        /* end trylevel of that block */
  72     int              catch_level;      /* initial trylevel of the catch block */
  73     int              catchblock_count; /* count of catch blocks in array */
  74     catchblock_info *catchblock;       /* array of catch blocks */
  75 } tryblock_info;
  76
  77 /* info about the unwind handler for a given trylevel */
  78 typedef struct __unwind_info
  79 {
  80     int    prev;          /* prev trylevel unwind handler, to run after this one */
  81     void (*handler)();    /* unwind handler */
  82 } unwind_info;
  83
  84 /* descriptor of all try blocks of a given function */
  85 typedef struct __cxx_function_descr
  86 {
  87     UINT           magic;          /* must be CXX_FRAME_MAGIC */
  88     UINT           unwind_count;   /* number of unwind handlers */
  89     unwind_info   *unwind_table;   /* array of unwind handlers */
  90     UINT           tryblock_count; /* number of try blocks */
  91     tryblock_info *tryblock;       /* array of try blocks */
  92     UINT           unknown[3];
  93 } cxx_function_descr;
  94
  95 /* complete information about a C++ type */
  96 typedef struct __cxx_type_info
  97 {
  98     UINT        flags;         /* flags (see CLASS_* flags below) */
  99     type_info  *type_info;     /* C++ type info */
 100     int         this_offset;   /* offset of base class this pointer from start of object */
 101     int         vbase_descr;   /* offset of virtual base class descriptor */
 102     int         vbase_offset;  /* offset of this pointer offset in virtual base class descriptor */
 103     size_t      size;          /* object size */
 104     void      (*copy_ctor)();  /* copy constructor */
 105 } cxx_type_info;
 106 #define CLASS_IS_SIMPLE_TYPE          1
 107 #define CLASS_HAS_VIRTUAL_BASE_CLASS  4
 108
 109 /* table of C++ types that apply for a given object */
 110 typedef struct __cxx_type_info_table
 111 {
 112     UINT           count;     /* number of types */
 113     cxx_type_info *info[1];   /* array of types */
 114 } cxx_type_info_table;
 115
 116 typedef DWORD (*cxx_exc_custom_handler)( PEXCEPTION_RECORD, cxx_exception_frame*,
 117                                          PCONTEXT, struct __EXCEPTION_FRAME**,
 118                                          cxx_function_descr*, int nested_trylevel,
 119                                          EXCEPTION_FRAME *nested_frame, DWORD unknown3 );
 120
 121 /* type information for an exception object */
 122 typedef struct __cxx_exception_type
 123 {
 124     UINT                   flags;            /* TYPE_FLAG flags */
 125     void                 (*destructor)();    /* exception object destructor */
 126     cxx_exc_custom_handler custom_handler;   /* custom handler for this exception */
 127     cxx_type_info_table   *type_info_table;  /* list of types for this exception object */
 128 } cxx_exception_type;
 129
 130
 131 #ifdef __i386__  /* CxxFrameHandler is not supported on non-i386 */
 132
 133 static DWORD cxx_frame_handler( PEXCEPTION_RECORD rec, cxx_exception_frame* frame,
 134                                 PCONTEXT exc_context, EXCEPTION_FRAME** dispatch,
 135                                 cxx_function_descr *descr, EXCEPTION_FRAME* nested_frame,
 136                                 int nested_trylevel, CONTEXT86 *context );
 137
 138 /* call a function with a given ebp */
 139 inline static void *call_ebp_func( void *func, void *ebp )
 140 {
 141     void *ret;
 142     __asm__ __volatile__ ("pushl %%ebp; movl %2,%%ebp; call *%%eax;; popl %%ebp" \
 143                           : "=a" (ret) : "0" (func), "g" (ebp));
 144     return ret;
 145 }
 146
 147 /* call a copy constructor */
 148 inline static void call_copy_ctor( void *func, void *this, void *src, int has_vbase )
 149 {
 150     TRACE( "calling copy ctor %p object %p src %p\n", func, this, src );
 151     if (has_vbase)
 152         /* in that case copy ctor takes an extra bool indicating whether to copy the base class */
 153         __asm__ __volatile__("pushl $1; pushl %2; call *%0"
 154                              : : "r" (func), "c" (this), "g" (src) );
 155     else
 156         __asm__ __volatile__("pushl %2; call *%0"
 157                              : : "r" (func), "c" (this), "g" (src) );
 158 }
 159
 160 /* call the destructor of the exception object */
 161 inline static void call_dtor( void *func, void *object )
 162 {
 163     __asm__ __volatile__("call *%0" : : "r" (func), "c" (object) );
 164 }
 165
 166
 167 static void dump_type( cxx_type_info *type )
 168 {
 169     DPRINTF( "flags %x type %p", type->flags, type->type_info );
 170     if (type->type_info) DPRINTF( " (%p %s)", type->type_info->data, type->type_info->name );
 171     DPRINTF( " offset %d vbase %d,%d size %d copy ctor %p\n", type->this_offset,
 172              type->vbase_descr, type->vbase_offset, type->size, type->copy_ctor );
 173 }
 174
 175 static void dump_exception_type( cxx_exception_type *type )
 176 {
 177     int i;
 178
 179     DPRINTF( "exception type:\n" );
 180     DPRINTF( "flags %x destr %p handler %p type info %p\n",
 181              type->flags, type->destructor, type->custom_handler, type->type_info_table );
 182     for (i = 0; i < type->type_info_table->count; i++)
 183     {
 184         DPRINTF( "    %d: ", i );
 185         dump_type( type->type_info_table->info[i] );
 186     }
 187 }
 188
 189 static void dump_function_descr( cxx_function_descr *descr, cxx_exception_type *info )
 190 {
 191     int i, j;
 192
 193     DPRINTF( "function descr:\n" );
 194     DPRINTF( "magic %x\n", descr->magic );
 195     DPRINTF( "unwind table: %p %d\n", descr->unwind_table, descr->unwind_count );
 196     for (i = 0; i < descr->unwind_count; i++)
 197     {
 198         DPRINTF( "    %d: prev %d func %p\n", i,
 199                  descr->unwind_table[i].prev, descr->unwind_table[i].handler );
 200     }
 201     DPRINTF( "try table: %p %d\n", descr->tryblock, descr->tryblock_count );
 202     for (i = 0; i < descr->tryblock_count; i++)
 203     {
 204         DPRINTF( "    %d: start %d end %d catchlevel %d catch %p %d\n", i,
 205                  descr->tryblock[i].start_level, descr->tryblock[i].end_level,
 206                  descr->tryblock[i].catch_level, descr->tryblock[i].catchblock,
 207                  descr->tryblock[i].catchblock_count );
 208         for (j = 0; j < descr->tryblock[i].catchblock_count; j++)
 209         {
 210             catchblock_info *ptr = &descr->tryblock[i].catchblock[j];
 211             DPRINTF( "        %d: flags %x offset %d handler %p type %p",
 212                      j, ptr->flags, ptr->offset, ptr->handler, ptr->type_info );
 213             if (ptr->type_info) DPRINTF( " (%p %s)", ptr->type_info->data, ptr->type_info->name );
 214             DPRINTF( "\n" );
 215         }
 216     }
 217 }
 218
 219 /* compute the this pointer for a base class of a given type */
 220 static void *get_this_pointer( cxx_type_info *type, void *object )
 221 {
 222     void *this_ptr;
 223     int *offset_ptr;
 224
 225     if (!object) return NULL;
 226     this_ptr = (char *)object + type->this_offset;
 227     if (type->vbase_descr >= 0)
 228     {
 229         /* move this ptr to vbase descriptor */
 230         this_ptr = (char *)this_ptr + type->vbase_descr;
 231         /* and fetch additional offset from vbase descriptor */
 232         offset_ptr = (int *)(*(char **)this_ptr + type->vbase_offset);
 233         this_ptr = (char *)this_ptr + *offset_ptr;
 234     }
 235     return this_ptr;
 236 }
 237
 238 /* check if the exception type is caught by a given catch block, and return the type that matched */
 239 static cxx_type_info *find_caught_type( cxx_exception_type *exc_type, catchblock_info *catchblock )
 240 {
 241     UINT i;
 242
 243     for (i = 0; i < exc_type->type_info_table->count; i++)
 244     {
 245         cxx_type_info *type = exc_type->type_info_table->info[i];
 246
 247         if (!catchblock->type_info) return type;   /* catch(...) matches any type */
 248         if (catchblock->type_info != type->type_info)
 249         {
 250             if (strcmp( catchblock->type_info->name, type->type_info->name )) continue;
 251         }
 252         /* type is the same, now check the flags */
 253         if ((exc_type->flags & TYPE_FLAG_CONST) &&
 254             !(catchblock->flags & TYPE_FLAG_CONST)) continue;
 255         if ((exc_type->flags & TYPE_FLAG_VOLATILE) &&
 256             !(catchblock->flags & TYPE_FLAG_VOLATILE)) continue;
 257         return type;  /* it matched */
 258     }
 259     return NULL;
 260 }
 261
 262
 263 /* copy the exception object where the catch block wants it */
 264 static void copy_exception( void *object, cxx_exception_frame *frame,
 265                             catchblock_info *catchblock, cxx_type_info *type )
 266 {
 267     void **dest_ptr;
 268
 269     if (!catchblock->type_info || !catchblock->type_info->name[0]) return;
 270     if (!catchblock->offset) return;
 271     dest_ptr = (void **)((char *)&frame->ebp + catchblock->offset);
 272
 273     if (catchblock->flags & TYPE_FLAG_REFERENCE)
 274     {
 275         *dest_ptr = get_this_pointer( type, object );
 276     }
 277     else if (type->flags & CLASS_IS_SIMPLE_TYPE)
 278     {
 279         memmove( dest_ptr, object, type->size );
 280         /* if it is a pointer, adjust it */
 281         if (type->size == sizeof(void *)) *dest_ptr = get_this_pointer( type, *dest_ptr );
 282     }
 283     else  /* copy the object */
 284     {
 285         if (type->copy_ctor)
 286             call_copy_ctor( type->copy_ctor, dest_ptr, get_this_pointer(type,object),
 287                             (type->flags & CLASS_HAS_VIRTUAL_BASE_CLASS) );
 288         else
 289             memmove( dest_ptr, get_this_pointer(type,object), type->size );
 290     }
 291 }
 292
 293 /* unwind the local function up to a given trylevel */
 294 static void cxx_local_unwind( cxx_exception_frame* frame, cxx_function_descr *descr, int last_level)
 295 {
 296     void (*handler)();
 297     int trylevel = frame->trylevel;
 298
 299     while (trylevel != last_level)
 300     {
 301         if (trylevel < 0 || trylevel >= descr->unwind_count)
 302         {
 303             ERR( "invalid trylevel %d\n", trylevel );
 304             MSVCRT_terminate();
 305         }
 306         handler = descr->unwind_table[trylevel].handler;
 307         if (handler)
 308         {
 309             TRACE( "calling unwind handler %p trylevel %d last %d ebp %p\n",
 310                    handler, trylevel, last_level, &frame->ebp );
 311             call_ebp_func( handler, &frame->ebp );
 312         }
 313         trylevel = descr->unwind_table[trylevel].prev;
 314     }
 315     frame->trylevel = last_level;
 316 }
 317
 318 /* exception frame for nested exceptions in catch block */
 319 struct catch_func_nested_frame
 320 {
 321     EXCEPTION_FRAME      frame;     /* standard exception frame */
 322     EXCEPTION_RECORD    *prev_rec;  /* previous record to restore in thread data */
 323     cxx_exception_frame *cxx_frame; /* frame of parent exception */
 324     cxx_function_descr  *descr;     /* descriptor of parent exception */
 325     int                  trylevel;  /* current try level */
 326 };
 327
 328 /* handler for exceptions happening while calling a catch function */
 329 static DWORD catch_function_nested_handler( EXCEPTION_RECORD *rec, EXCEPTION_FRAME *frame,
 330                                             CONTEXT *context, EXCEPTION_FRAME **dispatcher )
 331 {
 332     struct catch_func_nested_frame *nested_frame = (struct catch_func_nested_frame *)frame;
 333
 334     if (rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND))
 335     {
 336         msvcrt_get_thread_data()->exc_record = nested_frame->prev_rec;
 337         return ExceptionContinueSearch;
 338     }
 339     else
 340     {
 341         TRACE( "got nested exception in catch function\n" );
 342         return cxx_frame_handler( rec, nested_frame->cxx_frame, context,
 343                                   NULL, nested_frame->descr, &nested_frame->frame,
 344                                   nested_frame->trylevel, context );
 345     }
 346 }
 347
 348 /* find and call the appropriate catch block for an exception */
 349 /* returns the address to continue execution to after the catch block was called */
 350 inline static void *call_catch_block( PEXCEPTION_RECORD rec, cxx_exception_frame *frame,
 351                                       cxx_function_descr *descr, int nested_trylevel,
 352                                       cxx_exception_type *info )
 353 {
 354     int i, j;
 355     void *addr, *object = (void *)rec->ExceptionInformation[1];
 356     struct catch_func_nested_frame nested_frame;
 357     int trylevel = frame->trylevel;
 358     MSVCRT_thread_data *thread_data = msvcrt_get_thread_data();
 359
 360     for (i = 0; i < descr->tryblock_count; i++)
 361     {
 362         tryblock_info *tryblock = &descr->tryblock[i];
 363
 364         if (trylevel < tryblock->start_level) continue;
 365         if (trylevel > tryblock->end_level) continue;
 366
 367         /* got a try block */
 368         for (j = 0; j < tryblock->catchblock_count; j++)
 369         {
 370             catchblock_info *catchblock = &tryblock->catchblock[j];
 371             cxx_type_info *type = find_caught_type( info, catchblock );
 372             if (!type) continue;
 373
 374             TRACE( "matched type %p in tryblock %d catchblock %d\n", type, i, j );
 375
 376             /* copy the exception to its destination on the stack */
 377             copy_exception( object, frame, catchblock, type );
 378
 379             /* unwind the stack */
 380             RtlUnwind( frame, 0, rec, 0 );
 381             cxx_local_unwind( frame, descr, tryblock->start_level );
 382             frame->trylevel = tryblock->end_level + 1;
 383
 384             /* call the catch block */
 385             TRACE( "calling catch block %p for type %p addr %p ebp %p\n",
 386                    catchblock, type, catchblock->handler, &frame->ebp );
 387
 388             /* setup an exception block for nested exceptions */
 389
 390             nested_frame.frame.Handler = catch_function_nested_handler;
 391             nested_frame.prev_rec  = thread_data->exc_record;
 392             nested_frame.cxx_frame = frame;
 393             nested_frame.descr     = descr;
 394             nested_frame.trylevel  = nested_trylevel + 1;
 395
 396             __wine_push_frame( &nested_frame.frame );
 397             thread_data->exc_record = rec;
 398             addr = call_ebp_func( catchblock->handler, &frame->ebp );
 399             thread_data->exc_record = nested_frame.prev_rec;
 400             __wine_pop_frame( &nested_frame.frame );
 401
 402             if (info->destructor) call_dtor( info->destructor, object );
 403             TRACE( "done, continuing at %p\n", addr );
 404             return addr;
 405         }
 406     }
 407     return NULL;
 408 }
 409
 410
 411 /*********************************************************************
 412  *              cxx_frame_handler
 413  *
 414  * Implementation of __CxxFrameHandler.
 415  */
 416 static DWORD cxx_frame_handler( PEXCEPTION_RECORD rec, cxx_exception_frame* frame,
 417                                 PCONTEXT exc_context, EXCEPTION_FRAME** dispatch,
 418                                 cxx_function_descr *descr, EXCEPTION_FRAME* nested_frame,
 419                                 int nested_trylevel, CONTEXT86 *context )
 420 {
 421     cxx_exception_type *exc_type;
 422     void *next_ip;
 423
 424     if (descr->magic != CXX_FRAME_MAGIC)
 425     {
 426         ERR( "invalid frame magic %x\n", descr->magic );
 427         return ExceptionContinueSearch;
 428     }
 429     if (rec->ExceptionFlags & (EH_UNWINDING|EH_EXIT_UNWIND))
 430     {
 431         if (descr->unwind_count && !nested_trylevel) cxx_local_unwind( frame, descr, -1 );
 432         return ExceptionContinueSearch;
 433     }
 434     if (!descr->tryblock_count) return ExceptionContinueSearch;
 435
 436     exc_type = (cxx_exception_type *)rec->ExceptionInformation[2];
 437     if (rec->ExceptionCode == CXX_EXCEPTION &&
 438         rec->ExceptionInformation[0] > CXX_FRAME_MAGIC &&
 439         exc_type->custom_handler)
 440     {
 441         return exc_type->custom_handler( rec, frame, exc_context, dispatch,
 442                                          descr, nested_trylevel, nested_frame, 0 );
 443     }
 444
 445     if (!exc_type)  /* nested exception, fetch info from original exception */
 446     {
 447         rec = msvcrt_get_thread_data()->exc_record;
 448         exc_type = (cxx_exception_type *)rec->ExceptionInformation[2];
 449     }
 450
 451     if (TRACE_ON(seh))
 452     {
 453         TRACE("handling C++ exception rec %p frame %p trylevel %d descr %p nested_frame %p\n",
 454               rec, frame, frame->trylevel, descr, nested_frame );
 455         dump_exception_type( exc_type );
 456         dump_function_descr( descr, exc_type );
 457     }
 458
 459     next_ip = call_catch_block( rec, frame, descr, frame->trylevel, exc_type );
 460
 461     if (!next_ip) return ExceptionContinueSearch;
 462     rec->ExceptionFlags &= ~EH_NONCONTINUABLE;
 463     context->Eip = (DWORD)next_ip;
 464     context->Ebp = (DWORD)&frame->ebp;
 465     context->Esp = ((DWORD*)frame)[-1];
 466     return ExceptionContinueExecution;
 467 }
 468
 469
 470 /*********************************************************************
 471  *              __CxxFrameHandler (MSVCRT.@)
 472  */
 473 void __CxxFrameHandler( PEXCEPTION_RECORD rec, EXCEPTION_FRAME* frame,
 474                         PCONTEXT exc_context, EXCEPTION_FRAME** dispatch,
 475                         CONTEXT86 *context )
 476 {
 477     cxx_function_descr *descr = (cxx_function_descr *)context->Eax;
 478     context->Eax = cxx_frame_handler( rec, (cxx_exception_frame *)frame,
 479                                       exc_context, dispatch, descr, NULL, 0, context );
 480 }
 481
 482 #endif  /* __i386__ */
 483
 484 /*********************************************************************
 485  *              _CxxThrowException (MSVCRT.@)
 486  */
 487 void _CxxThrowException( void *object, cxx_exception_type *type )
 488 {
 489     DWORD args[3];
 490
 491     args[0] = CXX_FRAME_MAGIC;
 492     args[1] = (DWORD)object;
 493     args[2] = (DWORD)type;
 494     RaiseException( CXX_EXCEPTION, EH_NONCONTINUABLE, 3, args );
 495 }