git.oblomov.eu Git - wine/blob - dlls/msvcrt/except.c

   1 /*
   2  * msvcrt.dll exception handling
   3  *
   4  * Copyright 2000 Jon Griffiths
   5  * Copyright 2005 Juan Lang
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  20  *
  21  * NOTES:
  22  *
  23  * See http://www.microsoft.com/msj/0197/exception/exception.htm,
  24  * but don't believe all of it.
  25  *
  26  * FIXME: Incomplete support for nested exceptions/try block cleanup.
  27  */
  28
  29 #include "config.h"
  30 #include "wine/port.h"
  31
  32 #include <stdarg.h>
  33
  34 #include "windef.h"
  35 #include "winbase.h"
  36 #include "winternl.h"
  37 #include "wine/exception.h"
  38 #include "msvcrt.h"
  39 #include "excpt.h"
  40 #include "wincon.h"
  41 #include "msvcrt/float.h"
  42 #include "wine/debug.h"
  43
  44 WINE_DEFAULT_DEBUG_CHANNEL(seh);
  45
  46 /* VC++ extensions to Win32 SEH */
  47 typedef struct _SCOPETABLE
  48 {
  49   int previousTryLevel;
  50   int (*lpfnFilter)(PEXCEPTION_POINTERS);
  51   int (*lpfnHandler)(void);
  52 } SCOPETABLE, *PSCOPETABLE;
  53
  54 typedef struct _MSVCRT_EXCEPTION_FRAME
  55 {
  56   EXCEPTION_REGISTRATION_RECORD *prev;
  57   void (*handler)(PEXCEPTION_RECORD, EXCEPTION_REGISTRATION_RECORD*,
  58                   PCONTEXT, PEXCEPTION_RECORD);
  59   PSCOPETABLE scopetable;
  60   int trylevel;
  61   int _ebp;
  62   PEXCEPTION_POINTERS xpointers;
  63 } MSVCRT_EXCEPTION_FRAME;
  64
  65 #define TRYLEVEL_END (-1) /* End of trylevel list */
  66
  67 #if defined(__GNUC__) && defined(__i386__)
  68 static inline void call_finally_block( void *code_block, void *base_ptr )
  69 {
  70     __asm__ __volatile__ ("movl %1,%%ebp; call *%%eax"
  71                           : : "a" (code_block), "g" (base_ptr));
  72 }
  73
  74 static inline int call_filter( int (*func)(PEXCEPTION_POINTERS), void *arg, void *ebp )
  75 {
  76     int ret;
  77     __asm__ __volatile__ ("pushl %%ebp; pushl %3; movl %2,%%ebp; call *%%eax; popl %%ebp; popl %%ebp"
  78                           : "=a" (ret)
  79                           : "0" (func), "r" (ebp), "r" (arg)
  80                           : "ecx", "edx", "memory" );
  81     return ret;
  82 }
  83
  84 static inline int call_unwind_func( int (*func)(void), void *ebp )
  85 {
  86     int ret;
  87     __asm__ __volatile__ ("pushl %%ebp\n\t"
  88                           "pushl %%ebx\n\t"
  89                           "pushl %%esi\n\t"
  90                           "pushl %%edi\n\t"
  91                           "movl %2,%%ebp\n\t"
  92                           "call *%0\n\t"
  93                           "popl %%edi\n\t"
  94                           "popl %%esi\n\t"
  95                           "popl %%ebx\n\t"
  96                           "popl %%ebp"
  97                           : "=a" (ret)
  98                           : "0" (func), "r" (ebp)
  99                           : "ecx", "edx", "memory" );
 100     return ret;
 101 }
 102
 103 #endif
 104
 105 static DWORD MSVCRT_nested_handler(PEXCEPTION_RECORD rec,
 106                                    EXCEPTION_REGISTRATION_RECORD* frame,
 107                                    PCONTEXT context,
 108                                    EXCEPTION_REGISTRATION_RECORD** dispatch)
 109 {
 110   if (!(rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND)))
 111     return ExceptionContinueSearch;
 112   *dispatch = frame;
 113   return ExceptionCollidedUnwind;
 114 }
 115
 116
 117 /*********************************************************************
 118  *              _EH_prolog (MSVCRT.@)
 119  */
 120 #ifdef __i386__
 121 /* Provided for VC++ binary compatibility only */
 122 __ASM_GLOBAL_FUNC(_EH_prolog,
 123                   "pushl $-1\n\t"
 124                   "pushl %eax\n\t"
 125                   "pushl %fs:0\n\t"
 126                   "movl  %esp, %fs:0\n\t"
 127                   "movl  12(%esp), %eax\n\t"
 128                   "movl  %ebp, 12(%esp)\n\t"
 129                   "leal  12(%esp), %ebp\n\t"
 130                   "pushl %eax\n\t"
 131                   "ret")
 132
 133 static void msvcrt_local_unwind2(MSVCRT_EXCEPTION_FRAME* frame, int trylevel, void *ebp)
 134 {
 135   EXCEPTION_REGISTRATION_RECORD reg;
 136
 137   TRACE("(%p,%d,%d)\n",frame, frame->trylevel, trylevel);
 138
 139   /* Register a handler in case of a nested exception */
 140   reg.Handler = MSVCRT_nested_handler;
 141   reg.Prev = NtCurrentTeb()->Tib.ExceptionList;
 142   __wine_push_frame(&reg);
 143
 144   while (frame->trylevel != TRYLEVEL_END && frame->trylevel != trylevel)
 145   {
 146       int level = frame->trylevel;
 147       frame->trylevel = frame->scopetable[level].previousTryLevel;
 148       if (!frame->scopetable[level].lpfnFilter)
 149       {
 150           TRACE( "__try block cleanup level %d handler %p ebp %p\n",
 151                  level, frame->scopetable[level].lpfnHandler, ebp );
 152           call_unwind_func( frame->scopetable[level].lpfnHandler, ebp );
 153       }
 154   }
 155   __wine_pop_frame(&reg);
 156   TRACE("unwound OK\n");
 157 }
 158
 159 /*******************************************************************
 160  *              _local_unwind2 (MSVCRT.@)
 161  */
 162 void CDECL _local_unwind2(MSVCRT_EXCEPTION_FRAME* frame, int trylevel)
 163 {
 164     msvcrt_local_unwind2( frame, trylevel, &frame->_ebp );
 165 }
 166
 167 #endif  /* __i386__ */
 168
 169 /*******************************************************************
 170  *              _global_unwind2 (MSVCRT.@)
 171  */
 172 void CDECL _global_unwind2(EXCEPTION_REGISTRATION_RECORD* frame)
 173 {
 174     TRACE("(%p)\n",frame);
 175     RtlUnwind( frame, 0, 0, 0 );
 176 }
 177
 178 /*********************************************************************
 179  *              _except_handler2 (MSVCRT.@)
 180  */
 181 int CDECL _except_handler2(PEXCEPTION_RECORD rec,
 182                            EXCEPTION_REGISTRATION_RECORD* frame,
 183                            PCONTEXT context,
 184                            EXCEPTION_REGISTRATION_RECORD** dispatcher)
 185 {
 186   FIXME("exception %x flags=%x at %p handler=%p %p %p stub\n",
 187         rec->ExceptionCode, rec->ExceptionFlags, rec->ExceptionAddress,
 188         frame->Handler, context, dispatcher);
 189   return ExceptionContinueSearch;
 190 }
 191
 192 /*********************************************************************
 193  *              _except_handler3 (MSVCRT.@)
 194  */
 195 int CDECL _except_handler3(PEXCEPTION_RECORD rec,
 196                            MSVCRT_EXCEPTION_FRAME* frame,
 197                            PCONTEXT context, void* dispatcher)
 198 {
 199 #if defined(__GNUC__) && defined(__i386__)
 200   int retval, trylevel;
 201   EXCEPTION_POINTERS exceptPtrs;
 202   PSCOPETABLE pScopeTable;
 203
 204   TRACE("exception %x flags=%x at %p handler=%p %p %p semi-stub\n",
 205         rec->ExceptionCode, rec->ExceptionFlags, rec->ExceptionAddress,
 206         frame->handler, context, dispatcher);
 207
 208   __asm__ __volatile__ ("cld");
 209
 210   if (rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND))
 211   {
 212     /* Unwinding the current frame */
 213     msvcrt_local_unwind2(frame, TRYLEVEL_END, &frame->_ebp);
 214     TRACE("unwound current frame, returning ExceptionContinueSearch\n");
 215     return ExceptionContinueSearch;
 216   }
 217   else
 218   {
 219     /* Hunting for handler */
 220     exceptPtrs.ExceptionRecord = rec;
 221     exceptPtrs.ContextRecord = context;
 222     *((DWORD *)frame-1) = (DWORD)&exceptPtrs;
 223     trylevel = frame->trylevel;
 224     pScopeTable = frame->scopetable;
 225
 226     while (trylevel != TRYLEVEL_END)
 227     {
 228       if (pScopeTable[trylevel].lpfnFilter)
 229       {
 230         TRACE("filter = %p\n", pScopeTable[trylevel].lpfnFilter);
 231
 232         retval = call_filter( pScopeTable[trylevel].lpfnFilter, &exceptPtrs, &frame->_ebp );
 233
 234         TRACE("filter returned %s\n", retval == EXCEPTION_CONTINUE_EXECUTION ?
 235               "CONTINUE_EXECUTION" : retval == EXCEPTION_EXECUTE_HANDLER ?
 236               "EXECUTE_HANDLER" : "CONTINUE_SEARCH");
 237
 238         if (retval == EXCEPTION_CONTINUE_EXECUTION)
 239           return ExceptionContinueExecution;
 240
 241         if (retval == EXCEPTION_EXECUTE_HANDLER)
 242         {
 243           /* Unwind all higher frames, this one will handle the exception */
 244           _global_unwind2((EXCEPTION_REGISTRATION_RECORD*)frame);
 245           msvcrt_local_unwind2(frame, trylevel, &frame->_ebp);
 246
 247           /* Set our trylevel to the enclosing block, and call the __finally
 248            * code, which won't return
 249            */
 250           frame->trylevel = pScopeTable->previousTryLevel;
 251           TRACE("__finally block %p\n",pScopeTable[trylevel].lpfnHandler);
 252           call_finally_block(pScopeTable[trylevel].lpfnHandler, &frame->_ebp);
 253           ERR("Returned from __finally block - expect crash!\n");
 254        }
 255       }
 256       trylevel = pScopeTable->previousTryLevel;
 257     }
 258   }
 259 #else
 260   FIXME("exception %lx flags=%lx at %p handler=%p %p %p stub\n",
 261         rec->ExceptionCode, rec->ExceptionFlags, rec->ExceptionAddress,
 262         frame->handler, context, dispatcher);
 263 #endif
 264   TRACE("reached TRYLEVEL_END, returning ExceptionContinueSearch\n");
 265   return ExceptionContinueSearch;
 266 }
 267
 268 /*********************************************************************
 269  *              _abnormal_termination (MSVCRT.@)
 270  */
 271 int CDECL _abnormal_termination(void)
 272 {
 273   FIXME("(void)stub\n");
 274   return 0;
 275 }
 276
 277 /*
 278  * setjmp/longjmp implementation
 279  */
 280
 281 #ifdef __i386__
 282 #define MSVCRT_JMP_MAGIC 0x56433230 /* ID value for new jump structure */
 283 typedef void (__stdcall *MSVCRT_unwind_function)(const struct MSVCRT___JUMP_BUFFER *);
 284
 285 /* define an entrypoint for setjmp/setjmp3 that stores the registers in the jmp buf */
 286 /* and then jumps to the C backend function */
 287 #define DEFINE_SETJMP_ENTRYPOINT(name) \
 288     __ASM_GLOBAL_FUNC( name, \
 289                        "movl 4(%esp),%ecx\n\t"   /* jmp_buf */      \
 290                        "movl %ebp,0(%ecx)\n\t"   /* jmp_buf.Ebp */  \
 291                        "movl %ebx,4(%ecx)\n\t"   /* jmp_buf.Ebx */  \
 292                        "movl %edi,8(%ecx)\n\t"   /* jmp_buf.Edi */  \
 293                        "movl %esi,12(%ecx)\n\t"  /* jmp_buf.Esi */  \
 294                        "movl %esp,16(%ecx)\n\t"  /* jmp_buf.Esp */  \
 295                        "movl 0(%esp),%eax\n\t"                      \
 296                        "movl %eax,20(%ecx)\n\t"  /* jmp_buf.Eip */  \
 297                        "jmp " __ASM_NAME("__regs_") # name )
 298
 299 /* restore the registers from the jmp buf upon longjmp */
 300 extern void DECLSPEC_NORETURN longjmp_set_regs( struct MSVCRT___JUMP_BUFFER *jmp, int retval );
 301 __ASM_GLOBAL_FUNC( longjmp_set_regs,
 302                    "movl 4(%esp),%ecx\n\t"   /* jmp_buf */
 303                    "movl 8(%esp),%eax\n\t"   /* retval */
 304                    "movl 0(%ecx),%ebp\n\t"   /* jmp_buf.Ebp */
 305                    "movl 4(%ecx),%ebx\n\t"   /* jmp_buf.Ebx */
 306                    "movl 8(%ecx),%edi\n\t"   /* jmp_buf.Edi */
 307                    "movl 12(%ecx),%esi\n\t"  /* jmp_buf.Esi */
 308                    "movl 16(%ecx),%esp\n\t"  /* jmp_buf.Esp */
 309                    "addl $4,%esp\n\t"        /* get rid of return address */
 310                    "jmp *20(%ecx)\n\t"       /* jmp_buf.Eip */ )
 311
 312 /*
 313  * The signatures of the setjmp/longjmp functions do not match that
 314  * declared in the setjmp header so they don't follow the regular naming
 315  * convention to avoid conflicts.
 316  */
 317
 318 /*******************************************************************
 319  *              _setjmp (MSVCRT.@)
 320  */
 321 DEFINE_SETJMP_ENTRYPOINT(MSVCRT__setjmp)
 322 int CDECL __regs_MSVCRT__setjmp(struct MSVCRT___JUMP_BUFFER *jmp)
 323 {
 324     jmp->Registration = (unsigned long)NtCurrentTeb()->Tib.ExceptionList;
 325     if (jmp->Registration == ~0UL)
 326         jmp->TryLevel = TRYLEVEL_END;
 327     else
 328         jmp->TryLevel = ((MSVCRT_EXCEPTION_FRAME*)jmp->Registration)->trylevel;
 329
 330     TRACE("buf=%p ebx=%08lx esi=%08lx edi=%08lx ebp=%08lx esp=%08lx eip=%08lx frame=%08lx\n",
 331           jmp, jmp->Ebx, jmp->Esi, jmp->Edi, jmp->Ebp, jmp->Esp, jmp->Eip, jmp->Registration );
 332     return 0;
 333 }
 334
 335 /*******************************************************************
 336  *              _setjmp3 (MSVCRT.@)
 337  */
 338 DEFINE_SETJMP_ENTRYPOINT( MSVCRT__setjmp3 )
 339 int CDECL __regs_MSVCRT__setjmp3(struct MSVCRT___JUMP_BUFFER *jmp, int nb_args, ...)
 340 {
 341     jmp->Cookie = MSVCRT_JMP_MAGIC;
 342     jmp->UnwindFunc = 0;
 343     jmp->Registration = (unsigned long)NtCurrentTeb()->Tib.ExceptionList;
 344     if (jmp->Registration == ~0UL)
 345     {
 346         jmp->TryLevel = TRYLEVEL_END;
 347     }
 348     else
 349     {
 350         int i;
 351         va_list args;
 352
 353         va_start( args, nb_args );
 354         if (nb_args > 0) jmp->UnwindFunc = va_arg( args, unsigned long );
 355         if (nb_args > 1) jmp->TryLevel = va_arg( args, unsigned long );
 356         else jmp->TryLevel = ((MSVCRT_EXCEPTION_FRAME*)jmp->Registration)->trylevel;
 357         for (i = 0; i < 6 && i < nb_args - 2; i++)
 358             jmp->UnwindData[i] = va_arg( args, unsigned long );
 359         va_end( args );
 360     }
 361
 362     TRACE("buf=%p ebx=%08lx esi=%08lx edi=%08lx ebp=%08lx esp=%08lx eip=%08lx frame=%08lx\n",
 363           jmp, jmp->Ebx, jmp->Esi, jmp->Edi, jmp->Ebp, jmp->Esp, jmp->Eip, jmp->Registration );
 364     return 0;
 365 }
 366
 367 /*********************************************************************
 368  *              longjmp (MSVCRT.@)
 369  */
 370 int CDECL MSVCRT_longjmp(struct MSVCRT___JUMP_BUFFER *jmp, int retval)
 371 {
 372     unsigned long cur_frame = 0;
 373
 374     TRACE("buf=%p ebx=%08lx esi=%08lx edi=%08lx ebp=%08lx esp=%08lx eip=%08lx frame=%08lx retval=%08x\n",
 375           jmp, jmp->Ebx, jmp->Esi, jmp->Edi, jmp->Ebp, jmp->Esp, jmp->Eip, jmp->Registration, retval );
 376
 377     cur_frame=(unsigned long)NtCurrentTeb()->Tib.ExceptionList;
 378     TRACE("cur_frame=%lx\n",cur_frame);
 379
 380     if (cur_frame != jmp->Registration)
 381         _global_unwind2((EXCEPTION_REGISTRATION_RECORD*)jmp->Registration);
 382
 383     if (jmp->Registration)
 384     {
 385         if (!IsBadReadPtr(&jmp->Cookie, sizeof(long)) &&
 386             jmp->Cookie == MSVCRT_JMP_MAGIC && jmp->UnwindFunc)
 387         {
 388             MSVCRT_unwind_function unwind_func;
 389
 390             unwind_func=(MSVCRT_unwind_function)jmp->UnwindFunc;
 391             unwind_func(jmp);
 392         }
 393         else
 394             msvcrt_local_unwind2((MSVCRT_EXCEPTION_FRAME*)jmp->Registration,
 395                                  jmp->TryLevel, (void *)jmp->Ebp);
 396     }
 397
 398     if (!retval)
 399         retval = 1;
 400
 401     longjmp_set_regs( jmp, retval );
 402 }
 403
 404 /*********************************************************************
 405  *              _seh_longjmp_unwind (MSVCRT.@)
 406  */
 407 void __stdcall _seh_longjmp_unwind(struct MSVCRT___JUMP_BUFFER *jmp)
 408 {
 409     msvcrt_local_unwind2( (MSVCRT_EXCEPTION_FRAME *)jmp->Registration, jmp->TryLevel, (void *)jmp->Ebp );
 410 }
 411 #endif /* i386 */
 412
 413 static MSVCRT___sighandler_t sighandlers[MSVCRT_NSIG] = { MSVCRT_SIG_DFL };
 414
 415 static BOOL WINAPI msvcrt_console_handler(DWORD ctrlType)
 416 {
 417     BOOL ret = FALSE;
 418
 419     switch (ctrlType)
 420     {
 421     case CTRL_C_EVENT:
 422         if (sighandlers[MSVCRT_SIGINT])
 423         {
 424             if (sighandlers[MSVCRT_SIGINT] != MSVCRT_SIG_IGN)
 425                 sighandlers[MSVCRT_SIGINT](MSVCRT_SIGINT);
 426             ret = TRUE;
 427         }
 428         break;
 429     }
 430     return ret;
 431 }
 432
 433 typedef void (*float_handler)(int, int);
 434
 435 /* The exception codes are actually NTSTATUS values */
 436 static const struct
 437 {
 438     NTSTATUS status;
 439     int signal;
 440 } float_exception_map[] = {
 441  { EXCEPTION_FLT_DENORMAL_OPERAND, _FPE_DENORMAL },
 442  { EXCEPTION_FLT_DIVIDE_BY_ZERO, _FPE_ZERODIVIDE },
 443  { EXCEPTION_FLT_INEXACT_RESULT, _FPE_INEXACT },
 444  { EXCEPTION_FLT_INVALID_OPERATION, _FPE_INVALID },
 445  { EXCEPTION_FLT_OVERFLOW, _FPE_OVERFLOW },
 446  { EXCEPTION_FLT_STACK_CHECK, _FPE_STACKOVERFLOW },
 447  { EXCEPTION_FLT_UNDERFLOW, _FPE_UNDERFLOW },
 448 };
 449
 450 static LONG WINAPI msvcrt_exception_filter(struct _EXCEPTION_POINTERS *except)
 451 {
 452     LONG ret = EXCEPTION_CONTINUE_SEARCH;
 453     MSVCRT___sighandler_t handler;
 454
 455     if (!except || !except->ExceptionRecord)
 456         return EXCEPTION_CONTINUE_SEARCH;
 457
 458     switch (except->ExceptionRecord->ExceptionCode)
 459     {
 460     case EXCEPTION_ACCESS_VIOLATION:
 461         if ((handler = sighandlers[MSVCRT_SIGSEGV]) != MSVCRT_SIG_DFL)
 462         {
 463             if (handler != MSVCRT_SIG_IGN)
 464             {
 465                 sighandlers[MSVCRT_SIGSEGV] = MSVCRT_SIG_DFL;
 466                 handler(MSVCRT_SIGSEGV);
 467             }
 468             ret = EXCEPTION_CONTINUE_EXECUTION;
 469         }
 470         break;
 471     /* According to
 472      * http://msdn.microsoft.com/library/en-us/vclib/html/_CRT_signal.asp
 473      * the FPE signal handler takes as a second argument the type of
 474      * floating point exception.
 475      */
 476     case EXCEPTION_FLT_DENORMAL_OPERAND:
 477     case EXCEPTION_FLT_DIVIDE_BY_ZERO:
 478     case EXCEPTION_FLT_INEXACT_RESULT:
 479     case EXCEPTION_FLT_INVALID_OPERATION:
 480     case EXCEPTION_FLT_OVERFLOW:
 481     case EXCEPTION_FLT_STACK_CHECK:
 482     case EXCEPTION_FLT_UNDERFLOW:
 483         if ((handler = sighandlers[MSVCRT_SIGFPE]) != MSVCRT_SIG_DFL)
 484         {
 485             if (handler != MSVCRT_SIG_IGN)
 486             {
 487                 int i, float_signal = _FPE_INVALID;
 488
 489                 sighandlers[MSVCRT_SIGFPE] = MSVCRT_SIG_DFL;
 490                 for (i = 0; i < sizeof(float_exception_map) /
 491                          sizeof(float_exception_map[0]); i++)
 492                 {
 493                     if (float_exception_map[i].status ==
 494                         except->ExceptionRecord->ExceptionCode)
 495                     {
 496                         float_signal = float_exception_map[i].signal;
 497                         break;
 498                     }
 499                 }
 500                 ((float_handler)handler)(MSVCRT_SIGFPE, float_signal);
 501             }
 502             ret = EXCEPTION_CONTINUE_EXECUTION;
 503         }
 504         break;
 505     case EXCEPTION_ILLEGAL_INSTRUCTION:
 506         if ((handler = sighandlers[MSVCRT_SIGILL]) != MSVCRT_SIG_DFL)
 507         {
 508             if (handler != MSVCRT_SIG_IGN)
 509             {
 510                 sighandlers[MSVCRT_SIGILL] = MSVCRT_SIG_DFL;
 511                 handler(MSVCRT_SIGILL);
 512             }
 513             ret = EXCEPTION_CONTINUE_EXECUTION;
 514         }
 515         break;
 516     }
 517     return ret;
 518 }
 519
 520 void msvcrt_init_signals(void)
 521 {
 522     SetConsoleCtrlHandler(msvcrt_console_handler, TRUE);
 523     SetUnhandledExceptionFilter(msvcrt_exception_filter);
 524 }
 525
 526 void msvcrt_free_signals(void)
 527 {
 528     SetConsoleCtrlHandler(msvcrt_console_handler, FALSE);
 529     SetUnhandledExceptionFilter(NULL);
 530 }
 531
 532 /*********************************************************************
 533  *              signal (MSVCRT.@)
 534  * MS signal handling is described here:
 535  * http://msdn.microsoft.com/library/en-us/vclib/html/_CRT_signal.asp
 536  * Some signals may never be generated except through an explicit call to
 537  * raise.
 538  */
 539 MSVCRT___sighandler_t CDECL MSVCRT_signal(int sig, MSVCRT___sighandler_t func)
 540 {
 541     MSVCRT___sighandler_t ret = MSVCRT_SIG_ERR;
 542
 543     TRACE("(%d, %p)\n", sig, func);
 544
 545     if (func == MSVCRT_SIG_ERR) return MSVCRT_SIG_ERR;
 546
 547     switch (sig)
 548     {
 549     /* Cases handled internally.  Note SIGTERM is never generated by Windows,
 550      * so we effectively mask it.
 551      */
 552     case MSVCRT_SIGABRT:
 553     case MSVCRT_SIGFPE:
 554     case MSVCRT_SIGILL:
 555     case MSVCRT_SIGSEGV:
 556     case MSVCRT_SIGINT:
 557     case MSVCRT_SIGTERM:
 558         ret = sighandlers[sig];
 559         sighandlers[sig] = func;
 560         break;
 561     default:
 562         ret = MSVCRT_SIG_ERR;
 563     }
 564     return ret;
 565 }
 566
 567 /*********************************************************************
 568  *              raise (MSVCRT.@)
 569  */
 570 int CDECL MSVCRT_raise(int sig)
 571 {
 572     MSVCRT___sighandler_t handler;
 573
 574     TRACE("(%d)\n", sig);
 575
 576     switch (sig)
 577     {
 578     case MSVCRT_SIGABRT:
 579     case MSVCRT_SIGFPE:
 580     case MSVCRT_SIGILL:
 581     case MSVCRT_SIGSEGV:
 582     case MSVCRT_SIGINT:
 583     case MSVCRT_SIGTERM:
 584         handler = sighandlers[sig];
 585         if (handler == MSVCRT_SIG_DFL) MSVCRT__exit(3);
 586         if (handler != MSVCRT_SIG_IGN)
 587         {
 588             sighandlers[sig] = MSVCRT_SIG_DFL;
 589             if (sig == MSVCRT_SIGFPE)
 590                 ((float_handler)handler)(sig, _FPE_EXPLICITGEN);
 591             else
 592                 handler(sig);
 593         }
 594         break;
 595     default:
 596         return -1;
 597     }
 598     return 0;
 599 }
 600
 601 /*********************************************************************
 602  *              _XcptFilter (MSVCRT.@)
 603  */
 604 int CDECL _XcptFilter(NTSTATUS ex, PEXCEPTION_POINTERS ptr)
 605 {
 606     TRACE("(%08x,%p)\n", ex, ptr);
 607     /* I assume ptr->ExceptionRecord->ExceptionCode is the same as ex */
 608     return msvcrt_exception_filter(ptr);
 609 }