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 "ntddk.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 *prev;
  51     void           (*handler)(PEXCEPTION_RECORD, PEXCEPTION_FRAME, PCONTEXT, PEXCEPTION_RECORD);
  52     int              trylevel;
  53     DWORD            ebp;
  54 } cxx_exception_frame;
  55
  56 /* info about a single catch {} block */
  57 typedef struct __catchblock_info
  58 {
  59     UINT       flags;         /* flags (see below) */
  60     type_info *type_info;     /* C++ type caught by this block */
  61     int        offset;        /* stack offset to copy exception object to */
  62     void     (*handler)();    /* catch block handler code */
  63 } catchblock_info;
  64 #define TYPE_FLAG_CONST      1
  65 #define TYPE_FLAG_VOLATILE   2
  66 #define TYPE_FLAG_REFERENCE  8
  67
  68 /* info about a single try {} block */
  69 typedef struct __tryblock_info
  70 {
  71     int              start_level;      /* start trylevel of that block */
  72     int              end_level;        /* end trylevel of that block */
  73     int              catch_level;      /* initial trylevel of the catch block */
  74     int              catchblock_count; /* count of catch blocks in array */
  75     catchblock_info *catchblock;       /* array of catch blocks */
  76 } tryblock_info;
  77
  78 /* info about the unwind handler for a given trylevel */
  79 typedef struct __unwind_info
  80 {
  81     int    prev;          /* prev trylevel unwind handler, to run after this one */
  82     void (*handler)();    /* unwind handler */
  83 } unwind_info;
  84
  85 /* descriptor of all try blocks of a given function */
  86 typedef struct __cxx_function_descr
  87 {
  88     UINT           magic;          /* must be CXX_FRAME_MAGIC */
  89     UINT           unwind_count;   /* number of unwind handlers */
  90     unwind_info   *unwind_table;   /* array of unwind handlers */
  91     UINT           tryblock_count; /* number of try blocks */
  92     tryblock_info *tryblock;       /* array of try blocks */
  93     UINT           unknown[3];
  94 } cxx_function_descr;
  95
  96 /* complete information about a C++ type */
  97 typedef struct __cxx_type_info
  98 {
  99     UINT        flags;         /* flags (see CLASS_* flags below) */
 100     type_info  *type_info;     /* C++ type info */
 101     int         this_offset;   /* offset of base class this pointer from start of object */
 102     int         vbase_descr;   /* offset of virtual base class descriptor */
 103     int         vbase_offset;  /* offset of this pointer offset in virtual base class descriptor */
 104     size_t      size;          /* object size */
 105     void      (*copy_ctor)();  /* copy constructor */
 106 } cxx_type_info;
 107 #define CLASS_IS_SIMPLE_TYPE          1
 108 #define CLASS_HAS_VIRTUAL_BASE_CLASS  4
 109
 110 /* table of C++ types that apply for a given object */
 111 typedef struct __cxx_type_info_table
 112 {
 113     UINT           count;     /* number of types */
 114     cxx_type_info *info[1];   /* array of types */
 115 } cxx_type_info_table;
 116
 117 typedef DWORD (*cxx_exc_custom_handler)( PEXCEPTION_RECORD, cxx_exception_frame*,
 118                                          PCONTEXT, struct __EXCEPTION_FRAME**,
 119                                          cxx_function_descr*, DWORD unknown1,
 120                                          DWORD unknown2, DWORD unknown3 );
 121
 122 /* type information for an exception object */
 123 typedef struct __cxx_exception_type
 124 {
 125     UINT                   flags;            /* TYPE_FLAG flags */
 126     void                 (*destructor)();    /* exception object destructor */
 127     cxx_exc_custom_handler custom_handler;   /* custom handler for this exception */
 128     cxx_type_info_table   *type_info_table;  /* list of types for this exception object */
 129 } cxx_exception_type;
 130
 131
 132 #ifdef __i386__  /* CxxFrameHandler is not supported on non-i386 */
 133
 134 /* call a function with a given ebp */
 135 inline static void *call_ebp_func( void *func, void *ebp )
 136 {
 137     void *ret;
 138     __asm__ __volatile__ ("pushl %%ebp; movl %2,%%ebp; call *%%eax;; popl %%ebp" \
 139                           : "=a" (ret) : "0" (func), "g" (ebp));
 140     return ret;
 141 }
 142
 143 /* call a copy constructor */
 144 inline static void call_copy_ctor( void *func, void *this, void *src, int has_vbase )
 145 {
 146     TRACE( "calling copy ctor %p object %p src %p\n", func, this, src );
 147     if (has_vbase)
 148         /* in that case copy ctor takes an extra bool indicating whether to copy the base class */
 149         __asm__ __volatile__("pushl $1; pushl %2; call *%0"
 150                              : : "r" (func), "c" (this), "g" (src) );
 151     else
 152         __asm__ __volatile__("pushl %2; call *%0"
 153                              : : "r" (func), "c" (this), "g" (src) );
 154 }
 155
 156 /* call the destructor of the exception object */
 157 inline static void call_dtor( void *func, void *object )
 158 {
 159     __asm__ __volatile__("call *%0" : : "r" (func), "c" (object) );
 160 }
 161
 162
 163 static void dump_type( cxx_type_info *type )
 164 {
 165     DPRINTF( "flags %x type %p", type->flags, type->type_info );
 166     if (type->type_info) DPRINTF( " (%p %s)", type->type_info->data, type->type_info->name );
 167     DPRINTF( " offset %d vbase %d,%d size %d copy ctor %p\n", type->this_offset,
 168              type->vbase_descr, type->vbase_offset, type->size, type->copy_ctor );
 169 }
 170
 171 static void dump_exception_type( cxx_exception_type *type )
 172 {
 173     int i;
 174
 175     DPRINTF( "exception type:\n" );
 176     DPRINTF( "flags %x destr %p handler %p type info %p\n",
 177              type->flags, type->destructor, type->custom_handler, type->type_info_table );
 178     for (i = 0; i < type->type_info_table->count; i++)
 179     {
 180         DPRINTF( "    %d: ", i );
 181         dump_type( type->type_info_table->info[i] );
 182     }
 183 }
 184
 185 static void dump_function_descr( cxx_function_descr *descr, cxx_exception_type *info )
 186 {
 187     int i, j;
 188
 189     DPRINTF( "function descr:\n" );
 190     DPRINTF( "magic %x\n", descr->magic );
 191     DPRINTF( "unwind table: %p %d\n", descr->unwind_table, descr->unwind_count );
 192     for (i = 0; i < descr->unwind_count; i++)
 193     {
 194         DPRINTF( "    %d: prev %d func %p\n", i,
 195                  descr->unwind_table[i].prev, descr->unwind_table[i].handler );
 196     }
 197     DPRINTF( "try table: %p %d\n", descr->tryblock, descr->tryblock_count );
 198     for (i = 0; i < descr->tryblock_count; i++)
 199     {
 200         DPRINTF( "    %d: start %d end %d catchlevel %d catch %p %d\n", i,
 201                  descr->tryblock[i].start_level, descr->tryblock[i].end_level,
 202                  descr->tryblock[i].catch_level, descr->tryblock[i].catchblock,
 203                  descr->tryblock[i].catchblock_count );
 204         for (j = 0; j < descr->tryblock[i].catchblock_count; j++)
 205         {
 206             catchblock_info *ptr = &descr->tryblock[i].catchblock[j];
 207             DPRINTF( "        %d: flags %x offset %d handler %p type %p",
 208                      j, ptr->flags, ptr->offset, ptr->handler, ptr->type_info );
 209             if (ptr->type_info) DPRINTF( " (%p %s)", ptr->type_info->data, ptr->type_info->name );
 210             DPRINTF( "\n" );
 211         }
 212     }
 213 }
 214
 215 /* compute the this pointer for a base class of a given type */
 216 static void *get_this_pointer( cxx_type_info *type, void *object )
 217 {
 218     void *this_ptr;
 219     int *offset_ptr;
 220
 221     if (!object) return NULL;
 222     this_ptr = (char *)object + type->this_offset;
 223     if (type->vbase_descr >= 0)
 224     {
 225         /* move this ptr to vbase descriptor */
 226         this_ptr = (char *)this_ptr + type->vbase_descr;
 227         /* and fetch additional offset from vbase descriptor */
 228         offset_ptr = (int *)(*(char **)this_ptr + type->vbase_offset);
 229         this_ptr = (char *)this_ptr + *offset_ptr;
 230     }
 231     return this_ptr;
 232 }
 233
 234 /* check if the exception type is caught by a given catch block, and return the type that matched */
 235 static cxx_type_info *find_caught_type( cxx_exception_type *exc_type, catchblock_info *catchblock )
 236 {
 237     UINT i;
 238
 239     for (i = 0; i < exc_type->type_info_table->count; i++)
 240     {
 241         cxx_type_info *type = exc_type->type_info_table->info[i];
 242
 243         if (!catchblock->type_info) return type;   /* catch(...) matches any type */
 244         if (catchblock->type_info != type->type_info)
 245         {
 246             if (strcmp( catchblock->type_info->name, type->type_info->name )) continue;
 247         }
 248         /* type is the same, now check the flags */
 249         if ((exc_type->flags & TYPE_FLAG_CONST) &&
 250             !(catchblock->flags & TYPE_FLAG_CONST)) continue;
 251         if ((exc_type->flags & TYPE_FLAG_VOLATILE) &&
 252             !(catchblock->flags & TYPE_FLAG_VOLATILE)) continue;
 253         return type;  /* it matched */
 254     }
 255     return NULL;
 256 }
 257
 258
 259 /* copy the exception object where the catch block wants it */
 260 static void copy_exception( void *object, cxx_exception_frame *frame,
 261                             catchblock_info *catchblock, cxx_type_info *type )
 262 {
 263     void **dest_ptr;
 264
 265     if (!catchblock->type_info || !catchblock->type_info->name[0]) return;
 266     if (!catchblock->offset) return;
 267     dest_ptr = (void **)((char *)&frame->ebp + catchblock->offset);
 268
 269     if (catchblock->flags & TYPE_FLAG_REFERENCE)
 270     {
 271         *dest_ptr = get_this_pointer( type, object );
 272     }
 273     else if (type->flags & CLASS_IS_SIMPLE_TYPE)
 274     {
 275         memmove( dest_ptr, object, type->size );
 276         /* if it is a pointer, adjust it */
 277         if (type->size == sizeof(void *)) *dest_ptr = get_this_pointer( type, *dest_ptr );
 278     }
 279     else  /* copy the object */
 280     {
 281         if (type->copy_ctor)
 282             call_copy_ctor( type->copy_ctor, dest_ptr, get_this_pointer(type,object),
 283                             (type->flags & CLASS_HAS_VIRTUAL_BASE_CLASS) );
 284         else
 285             memmove( dest_ptr, get_this_pointer(type,object), type->size );
 286     }
 287 }
 288
 289 /* unwind the local function up to a given trylevel */
 290 static void cxx_local_unwind( cxx_exception_frame* frame, cxx_function_descr *descr, int last_level)
 291 {
 292     void (*handler)();
 293     int trylevel = frame->trylevel;
 294
 295     while (trylevel != last_level)
 296     {
 297         if (trylevel < 0 || trylevel >= descr->unwind_count)
 298         {
 299             ERR( "invalid trylevel %d\n", trylevel );
 300             MSVCRT_terminate();
 301         }
 302         handler = descr->unwind_table[trylevel].handler;
 303         if (handler)
 304         {
 305             TRACE( "calling unwind handler %p trylevel %d last %d ebp %p\n",
 306                    handler, trylevel, last_level, &frame->ebp );
 307             call_ebp_func( handler, &frame->ebp );
 308         }
 309         trylevel = descr->unwind_table[trylevel].prev;
 310     }
 311     frame->trylevel = last_level;
 312 }
 313
 314 /* find and call the appropriate catch block for an exception */
 315 /* returns the address to continue execution to after the catch block was called */
 316 inline static void *call_catch_block( PEXCEPTION_RECORD rec, cxx_exception_frame *frame,
 317                                       EXCEPTION_FRAME *unwind_frame,
 318                                       cxx_function_descr *descr, int trylevel,
 319                                       cxx_exception_type *info )
 320 {
 321     int i, j;
 322     void *addr, *object = (void *)rec->ExceptionInformation[1];
 323
 324     for (i = 0; i < descr->tryblock_count; i++)
 325     {
 326         tryblock_info *tryblock = &descr->tryblock[i];
 327
 328         if (trylevel < tryblock->start_level) continue;
 329         if (trylevel > tryblock->end_level) continue;
 330
 331         /* got a try block */
 332         for (j = 0; j < tryblock->catchblock_count; j++)
 333         {
 334             catchblock_info *catchblock = &tryblock->catchblock[j];
 335             cxx_type_info *type = find_caught_type( info, catchblock );
 336             if (!type) continue;
 337
 338             TRACE( "matched type %p in tryblock %d catchblock %d\n", type, i, j );
 339
 340             /* copy the exception to its destination on the stack */
 341             copy_exception( object, frame, catchblock, type );
 342
 343             /* unwind the stack */
 344             RtlUnwind( unwind_frame, 0, rec, 0 );
 345             cxx_local_unwind( frame, descr, tryblock->start_level );
 346             frame->trylevel = tryblock->end_level + 1;
 347
 348             /* call the catch block */
 349             TRACE( "calling catch block %p for type %p addr %p ebp %p\n",
 350                    catchblock, type, catchblock->handler, &frame->ebp );
 351             addr = call_ebp_func( catchblock->handler, &frame->ebp );
 352             if (info->destructor) call_dtor( info->destructor, object );
 353             TRACE( "done, continuing at %p\n", addr );
 354             return addr;
 355         }
 356     }
 357     return NULL;
 358 }
 359
 360
 361 /*********************************************************************
 362  *              cxx_frame_handler
 363  *
 364  * Implementation of __CxxFrameHandler.
 365  */
 366 static DWORD cxx_frame_handler( PEXCEPTION_RECORD rec, cxx_exception_frame* frame,
 367                                 PCONTEXT exc_context, EXCEPTION_FRAME** dispatch,
 368                                 cxx_function_descr *descr, CONTEXT86 *context )
 369 {
 370     cxx_exception_type *exc_type;
 371     void *next_ip;
 372
 373     if (descr->magic != CXX_FRAME_MAGIC)
 374     {
 375         ERR( "invalid frame magic %x\n", descr->magic );
 376         return ExceptionContinueSearch;
 377     }
 378     if (rec->ExceptionFlags & (EH_UNWINDING|EH_EXIT_UNWIND))
 379     {
 380         if (descr->unwind_count) cxx_local_unwind( frame, descr, -1 );
 381         return ExceptionContinueSearch;
 382     }
 383     if (!descr->tryblock_count) return ExceptionContinueSearch;
 384
 385     exc_type = (cxx_exception_type *)rec->ExceptionInformation[2];
 386     if (rec->ExceptionCode != CXX_EXCEPTION) goto normal_handler;
 387     if (rec->ExceptionInformation[0] != CXX_FRAME_MAGIC) goto normal_handler;
 388     if (exc_type->custom_handler)
 389         return exc_type->custom_handler( rec, frame, exc_context, dispatch, descr, 0, 0, 0 );
 390
 391  normal_handler:
 392     if (TRACE_ON(seh))
 393     {
 394         TRACE("handling C++ exception rec %p frame %p trylevel %d descr %p\n",
 395               rec, frame, frame->trylevel, descr );
 396         dump_exception_type( exc_type );
 397         dump_function_descr( descr, exc_type );
 398     }
 399
 400     next_ip = call_catch_block( rec, frame, (EXCEPTION_FRAME *)frame,
 401                                 descr, frame->trylevel, exc_type );
 402
 403     if (!next_ip) return ExceptionContinueSearch;
 404     context->Eip = (DWORD)next_ip;
 405     context->Ebp = (DWORD)&frame->ebp;
 406     context->Esp = ((DWORD*)frame)[-1];
 407     return ExceptionContinueExecution;
 408 }
 409
 410
 411 /*********************************************************************
 412  *              __CxxFrameHandler (MSVCRT.@)
 413  */
 414 void __CxxFrameHandler( PEXCEPTION_RECORD rec, EXCEPTION_FRAME* frame,
 415                         PCONTEXT exc_context, EXCEPTION_FRAME** dispatch,
 416                         CONTEXT86 *context )
 417 {
 418     cxx_function_descr *descr = (cxx_function_descr *)context->Eax;
 419     context->Eax = cxx_frame_handler( rec, (cxx_exception_frame *)frame,
 420                                       exc_context, dispatch, descr, context );
 421 }
 422
 423 #endif  /* __i386__ */
 424
 425 /*********************************************************************
 426  *              _CxxThrowException (MSVCRT.@)
 427  */
 428 void _CxxThrowException( void *object, cxx_exception_type *type )
 429 {
 430     DWORD args[3];
 431
 432     args[0] = CXX_FRAME_MAGIC;
 433     args[1] = (DWORD)object;
 434     args[2] = (DWORD)type;
 435     RaiseException( CXX_EXCEPTION, EH_NONCONTINUABLE, 3, args );
 436 }