win32/kernel32.c

   1 /*
   2  * KERNEL32 thunks and other undocumented stuff
   3  *
   4  * Copyright 1997-1998 Marcus Meissner
   5  * Copyright 1998      Ulrich Weigand
   6  */
   7
   8 #include "windows.h"
   9 #include "callback.h"
  10 #include "resource.h"
  11 #include "task.h"
  12 #include "user.h"
  13 #include "heap.h"
  14 #include "module.h"
  15 #include "process.h"
  16 #include "stackframe.h"
  17 #include "heap.h"
  18 #include "selectors.h"
  19 #include "task.h"
  20 #include "win.h"
  21 #include "file.h"
  22 #include "debug.h"
  23 #include "flatthunk.h"
  24 #include "syslevel.h"
  25
  26
  27 /***********************************************************************
  28  *                                                                     *
  29  *                 Win95 internal thunks                               *
  30  *                                                                     *
  31  ***********************************************************************/
  32
  33 /***********************************************************************
  34  * Generates a FT_Prolog call.
  35  *
  36  *  0FB6D1                  movzbl edx,cl
  37  *  8B1495xxxxxxxx          mov edx,[4*edx + targetTable]
  38  *  68xxxxxxxx              push FT_Prolog
  39  *  C3                      lret
  40  */
  41 static void _write_ftprolog(LPBYTE relayCode ,DWORD *targetTable) {
  42         LPBYTE  x;
  43
  44         x       = relayCode;
  45         *x++    = 0x0f;*x++=0xb6;*x++=0xd1; /* movzbl edx,cl */
  46         *x++    = 0x8B;*x++=0x14;*x++=0x95;*(DWORD**)x= targetTable;
  47         x+=4;   /* mov edx, [4*edx + targetTable] */
  48         *x++    = 0x68; *(DWORD*)x = (DWORD)GetProcAddress32(GetModuleHandle32A("KERNEL32"),"FT_Prolog");
  49         x+=4;   /* push FT_Prolog */
  50         *x++    = 0xC3;         /* lret */
  51         /* fill rest with 0xCC / int 3 */
  52 }
  53
  54 /***********************************************************************
  55  *      _write_qtthunk                                  (internal)
  56  * Generates a QT_Thunk style call.
  57  *
  58  *  33C9                    xor ecx, ecx
  59  *  8A4DFC                  mov cl , [ebp-04]
  60  *  8B148Dxxxxxxxx          mov edx, [4*ecx + targetTable]
  61  *  B8yyyyyyyy              mov eax, QT_Thunk
  62  *  FFE0                    jmp eax
  63  */
  64 static void _write_qtthunk(
  65         LPBYTE relayCode,       /* [in] start of QT_Thunk stub */
  66         DWORD *targetTable      /* [in] start of thunk (for index lookup) */
  67 ) {
  68         LPBYTE  x;
  69
  70         x       = relayCode;
  71         *x++    = 0x33;*x++=0xC9; /* xor ecx,ecx */
  72         *x++    = 0x8A;*x++=0x4D;*x++=0xFC; /* movb cl,[ebp-04] */
  73         *x++    = 0x8B;*x++=0x14;*x++=0x8D;*(DWORD**)x= targetTable;
  74         x+=4;   /* mov edx, [4*ecx + targetTable */
  75         *x++    = 0xB8; *(DWORD*)x = (DWORD)GetProcAddress32(GetModuleHandle32A("KERNEL32"),"QT_Thunk");
  76         x+=4;   /* mov eax , QT_Thunk */
  77         *x++    = 0xFF; *x++ = 0xE0;    /* jmp eax */
  78         /* should fill the rest of the 32 bytes with 0xCC */
  79 }
  80
  81 /***********************************************************************
  82  *           _loadthunk
  83  */
  84 static LPVOID _loadthunk(LPSTR module, LPSTR func, LPSTR module32,
  85                          struct ThunkDataCommon *TD32)
  86 {
  87     struct ThunkDataCommon *TD16;
  88     HMODULE32 hmod;
  89
  90     if ((hmod = LoadLibrary16(module)) <= 32)
  91     {
  92         ERR(thunk, "(%s, %s, %s, %p): Unable to load '%s', error %d\n",
  93                    module, func, module32, TD32, module, hmod);
  94         return 0;
  95     }
  96
  97     if (!(TD16 = PTR_SEG_TO_LIN(WIN32_GetProcAddress16(hmod, func))))
  98     {
  99         ERR(thunk, "(%s, %s, %s, %p): Unable to find '%s'\n",
 100                    module, func, module32, TD32, func);
 101         return 0;
 102     }
 103
 104     if (TD32 && memcmp(TD16->magic, TD32->magic, 4))
 105     {
 106         ERR(thunk, "(%s, %s, %s, %p): Bad magic %c%c%c%c (should be %c%c%c%c)\n",
 107                    module, func, module32, TD32,
 108                    TD16->magic[0], TD16->magic[1], TD16->magic[2], TD16->magic[3],
 109                    TD32->magic[0], TD32->magic[1], TD32->magic[2], TD32->magic[3]);
 110         return 0;
 111     }
 112
 113     if (TD32 && TD16->checksum != TD32->checksum)
 114     {
 115         ERR(thunk, "(%s, %s, %s, %p): Wrong checksum %08lx (should be %08lx)\n",
 116                    module, func, module32, TD32, TD16->checksum, TD32->checksum);
 117         return 0;
 118     }
 119
 120     return TD16;
 121 }
 122
 123 /***********************************************************************
 124  *           GetThunkStuff    (KERNEL32.53)
 125  */
 126 LPVOID WINAPI GetThunkStuff(LPSTR module, LPSTR func)
 127 {
 128     return _loadthunk(module, func, "<kernel>", NULL);
 129 }
 130
 131 /***********************************************************************
 132  *           GetThunkBuff    (KERNEL32.52)
 133  * Returns a pointer to ThkBuf in the 16bit library SYSTHUNK.DLL.
 134  */
 135 LPVOID WINAPI GetThunkBuff(void)
 136 {
 137     return GetThunkStuff("SYSTHUNK.DLL", "ThkBuf");
 138 }
 139
 140 /***********************************************************************
 141  *              ThunkConnect32          (KERNEL32)
 142  * Connects a 32bit and a 16bit thunkbuffer.
 143  */
 144 UINT32 WINAPI ThunkConnect32(
 145         struct ThunkDataCommon *TD,  /* [in/out] thunkbuffer */
 146         LPSTR thunkfun16,            /* [in] win16 thunkfunction */
 147         LPSTR module16,              /* [in] name of win16 dll */
 148         LPSTR module32,              /* [in] name of win32 dll */
 149         HMODULE32 hmod32,            /* [in] hmodule of win32 dll */
 150         DWORD dwReason               /* [in] initialisation argument */
 151 ) {
 152     BOOL32 directionSL;
 153
 154     if (!lstrncmp32A(TD->magic, "SL01", 4))
 155     {
 156         directionSL = TRUE;
 157
 158         TRACE(thunk, "SL01 thunk %s (%lx) <- %s (%s), Reason: %ld\n",
 159                      module32, (DWORD)TD, module16, thunkfun16, dwReason);
 160     }
 161     else if (!lstrncmp32A(TD->magic, "LS01", 4))
 162     {
 163         directionSL = FALSE;
 164
 165         TRACE(thunk, "LS01 thunk %s (%lx) -> %s (%s), Reason: %ld\n",
 166                      module32, (DWORD)TD, module16, thunkfun16, dwReason);
 167     }
 168     else
 169     {
 170         ERR(thunk, "Invalid magic %c%c%c%c\n",
 171                    TD->magic[0], TD->magic[1], TD->magic[2], TD->magic[3]);
 172         return 0;
 173     }
 174
 175     switch (dwReason)
 176     {
 177         case DLL_PROCESS_ATTACH:
 178         {
 179             struct ThunkDataCommon *TD16;
 180             if (!(TD16 = _loadthunk(module16, thunkfun16, module32, TD)))
 181                 return 0;
 182
 183             if (directionSL)
 184             {
 185                 struct ThunkDataSL32 *SL32 = (struct ThunkDataSL32 *)TD;
 186                 struct ThunkDataSL16 *SL16 = (struct ThunkDataSL16 *)TD16;
 187                 struct SLTargetDB *tdb;
 188
 189                 if (SL16->fpData == NULL)
 190                 {
 191                     ERR(thunk, "ThunkConnect16 was not called!\n");
 192                     return 0;
 193                 }
 194
 195                 SL32->data = SL16->fpData;
 196
 197                 tdb = HeapAlloc(GetProcessHeap(), 0, sizeof(*tdb));
 198                 tdb->process = PROCESS_Current();
 199                 tdb->targetTable = (DWORD *)(thunkfun16 + SL32->offsetTargetTable);
 200
 201                 tdb->next = SL32->data->targetDB;   /* FIXME: not thread-safe! */
 202                 SL32->data->targetDB = tdb;
 203
 204                 TRACE(thunk, "Process %08lx allocated TargetDB entry for ThunkDataSL %08lx\n",
 205                              (DWORD)PROCESS_Current(), (DWORD)SL32->data);
 206             }
 207             else
 208             {
 209                 struct ThunkDataLS32 *LS32 = (struct ThunkDataLS32 *)TD;
 210                 struct ThunkDataLS16 *LS16 = (struct ThunkDataLS16 *)TD16;
 211
 212                 LS32->targetTable = PTR_SEG_TO_LIN(LS16->targetTable);
 213
 214                 /* write QT_Thunk and FT_Prolog stubs */
 215                 _write_qtthunk ((LPBYTE)TD + LS32->offsetQTThunk,  LS32->targetTable);
 216                 _write_ftprolog((LPBYTE)TD + LS32->offsetFTProlog, LS32->targetTable);
 217             }
 218             break;
 219         }
 220
 221         case DLL_PROCESS_DETACH:
 222             /* FIXME: cleanup */
 223             break;
 224     }
 225
 226     return 1;
 227 }
 228
 229 /**********************************************************************
 230  *              QT_Thunk                        (KERNEL32)
 231  *
 232  * The target address is in EDX.
 233  * The 16 bit arguments start at ESP+4.
 234  * The number of 16bit argumentbytes is EBP-ESP-0x44 (68 Byte thunksetup).
 235  * [ok]
 236  */
 237 REGS_ENTRYPOINT(QT_Thunk)
 238 {
 239     CONTEXT context16;
 240     DWORD argsize;
 241     THDB *thdb = THREAD_Current();
 242
 243     memcpy(&context16,context,sizeof(context16));
 244
 245     CS_reg(&context16)  = HIWORD(EDX_reg(context));
 246     IP_reg(&context16)  = LOWORD(EDX_reg(context));
 247     EBP_reg(&context16) = OFFSETOF( thdb->cur_stack )
 248                            + (WORD)&((STACK16FRAME*)0)->bp;
 249
 250     argsize = EBP_reg(context)-ESP_reg(context)-0x44;
 251
 252     memcpy( ((LPBYTE)THREAD_STACK16(thdb))-argsize,
 253             (LPBYTE)ESP_reg(context)+4, argsize );
 254
 255     EAX_reg(context) = Callbacks->CallRegisterShortProc( &context16, argsize );
 256     EDX_reg(context) = HIWORD(EAX_reg(context));
 257 }
 258
 259
 260 /**********************************************************************
 261  *              FT_Prolog                       (KERNEL32.233)
 262  *
 263  * The set of FT_... thunk routines is used instead of QT_Thunk,
 264  * if structures have to be converted from 32-bit to 16-bit
 265  * (change of member alignment, conversion of members).
 266  *
 267  * The thunk function (as created by the thunk compiler) calls
 268  * FT_Prolog at the beginning, to set up a stack frame and
 269  * allocate a 64 byte buffer on the stack.
 270  * The input parameters (target address and some flags) are
 271  * saved for later use by FT_Thunk.
 272  *
 273  * Input:  EDX  16-bit target address (SEGPTR)
 274  *         CX   bits  0..7   target number (in target table)
 275  *              bits  8..9   some flags (unclear???)
 276  *              bits 10..15  number of DWORD arguments
 277  *
 278  * Output: A new stackframe is created, and a 64 byte buffer
 279  *         allocated on the stack. The layout of the stack
 280  *         on return is as follows:
 281  *
 282  *  (ebp+4)  return address to caller of thunk function
 283  *  (ebp)    old EBP
 284  *  (ebp-4)  saved EBX register of caller
 285  *  (ebp-8)  saved ESI register of caller
 286  *  (ebp-12) saved EDI register of caller
 287  *  (ebp-16) saved ECX register, containing flags
 288  *  (ebp-20) bitmap containing parameters that are to be converted
 289  *           by FT_Thunk; it is initialized to 0 by FT_Prolog and
 290  *           filled in by the thunk code before calling FT_Thunk
 291  *  (ebp-24)
 292  *    ...    (unclear)
 293  *  (ebp-44)
 294  *  (ebp-48) saved EAX register of caller (unclear, never restored???)
 295  *  (ebp-52) saved EDX register, containing 16-bit thunk target
 296  *  (ebp-56)
 297  *    ...    (unclear)
 298  *  (ebp-64)
 299  *
 300  *  ESP is EBP-68 on return.
 301  *
 302  */
 303
 304 REGS_ENTRYPOINT(FT_Prolog)
 305 {
 306     /* Pop return address to thunk code */
 307     EIP_reg(context) = STACK32_POP(context);
 308
 309     /* Build stack frame */
 310     STACK32_PUSH(context, EBP_reg(context));
 311     EBP_reg(context) = ESP_reg(context);
 312
 313     /* Allocate 64-byte Thunk Buffer */
 314     ESP_reg(context) -= 64;
 315     memset((char *)ESP_reg(context), '\0', 64);
 316
 317     /* Store Flags (ECX) and Target Address (EDX) */
 318     /* Save other registers to be restored later */
 319     *(DWORD *)(EBP_reg(context) -  4) = EBX_reg(context);
 320     *(DWORD *)(EBP_reg(context) -  8) = ESI_reg(context);
 321     *(DWORD *)(EBP_reg(context) - 12) = EDI_reg(context);
 322     *(DWORD *)(EBP_reg(context) - 16) = ECX_reg(context);
 323
 324     *(DWORD *)(EBP_reg(context) - 48) = EAX_reg(context);
 325     *(DWORD *)(EBP_reg(context) - 52) = EDX_reg(context);
 326
 327     /* Push return address back onto stack */
 328     STACK32_PUSH(context, EIP_reg(context));
 329 }
 330
 331 /**********************************************************************
 332  *              FT_Thunk                        (KERNEL32.234)
 333  *
 334  * This routine performs the actual call to 16-bit code,
 335  * similar to QT_Thunk. The differences are:
 336  *  - The call target is taken from the buffer created by FT_Prolog
 337  *  - Those arguments requested by the thunk code (by setting the
 338  *    corresponding bit in the bitmap at EBP-20) are converted
 339  *    from 32-bit pointers to segmented pointers (those pointers
 340  *    are guaranteed to point to structures copied to the stack
 341  *    by the thunk code, so we always use the 16-bit stack selector
 342  *    for those addresses).
 343  *
 344  *    The bit #i of EBP-20 corresponds here to the DWORD starting at
 345  *    ESP+4 + 2*i.
 346  *
 347  * FIXME: It is unclear what happens if there are more than 32 WORDs
 348  *        of arguments, so that the single DWORD bitmap is no longer
 349  *        sufficient ...
 350  */
 351
 352 REGS_ENTRYPOINT(FT_Thunk)
 353 {
 354     DWORD mapESPrelative = *(DWORD *)(EBP_reg(context) - 20);
 355     DWORD callTarget     = *(DWORD *)(EBP_reg(context) - 52);
 356
 357     CONTEXT context16;
 358     DWORD i, argsize;
 359     LPBYTE newstack, oldstack;
 360     THDB *thdb = THREAD_Current();
 361
 362     memcpy(&context16,context,sizeof(context16));
 363
 364     CS_reg(&context16)  = HIWORD(callTarget);
 365     IP_reg(&context16)  = LOWORD(callTarget);
 366     EBP_reg(&context16) = OFFSETOF( thdb->cur_stack )
 367                            + (WORD)&((STACK16FRAME*)0)->bp;
 368
 369     argsize  = EBP_reg(context)-ESP_reg(context)-0x44;
 370     newstack = ((LPBYTE)THREAD_STACK16(thdb))-argsize;
 371     oldstack = (LPBYTE)ESP_reg(context)+4;
 372
 373     memcpy( newstack, oldstack, argsize );
 374
 375     for (i = 0; i < 32; i++)    /* NOTE: What about > 32 arguments? */
 376         if (mapESPrelative & (1 << i))
 377         {
 378             SEGPTR *arg = (SEGPTR *)(newstack + 2*i);
 379             *arg = PTR_SEG_OFF_TO_SEGPTR(SELECTOROF(thdb->cur_stack),
 380                                          OFFSETOF(thdb->cur_stack) - argsize
 381                                          + (*(LPBYTE *)arg - oldstack));
 382         }
 383
 384     EAX_reg(context) = Callbacks->CallRegisterShortProc( &context16, argsize );
 385     EDX_reg(context) = HIWORD(EAX_reg(context));
 386 }
 387
 388 /**********************************************************************
 389  *              FT_ExitNN               (KERNEL32.218 - 232)
 390  *
 391  * One of the FT_ExitNN functions is called at the end of the thunk code.
 392  * It removes the stack frame created by FT_Prolog, moves the function
 393  * return from EBX to EAX (yes, FT_Thunk did use EAX for the return
 394  * value, but the thunk code has moved it from EAX to EBX in the
 395  * meantime ... :-), restores the caller's EBX, ESI, and EDI registers,
 396  * and perform a return to the CALLER of the thunk code (while removing
 397  * the given number of arguments from the caller's stack).
 398  */
 399
 400 static void FT_Exit(CONTEXT *context, int nPopArgs)
 401 {
 402     /* Return value is in EBX */
 403     EAX_reg(context) = EBX_reg(context);
 404
 405     /* Restore EBX, ESI, and EDI registers */
 406     EBX_reg(context) = *(DWORD *)(EBP_reg(context) -  4);
 407     ESI_reg(context) = *(DWORD *)(EBP_reg(context) -  8);
 408     EDI_reg(context) = *(DWORD *)(EBP_reg(context) - 12);
 409
 410     /* Clean up stack frame */
 411     ESP_reg(context) = EBP_reg(context);
 412     EBP_reg(context) = STACK32_POP(context);
 413
 414     /* Pop return address to CALLER of thunk code */
 415     EIP_reg(context) = STACK32_POP(context);
 416     /* Remove arguments */
 417     ESP_reg(context) += nPopArgs;
 418     /* Push return address back onto stack */
 419     STACK32_PUSH(context, EIP_reg(context));
 420 }
 421
 422 REGS_ENTRYPOINT(FT_Exit0)  { FT_Exit(context,  0); }
 423 REGS_ENTRYPOINT(FT_Exit4)  { FT_Exit(context,  4); }
 424 REGS_ENTRYPOINT(FT_Exit8)  { FT_Exit(context,  8); }
 425 REGS_ENTRYPOINT(FT_Exit12) { FT_Exit(context, 12); }
 426 REGS_ENTRYPOINT(FT_Exit16) { FT_Exit(context, 16); }
 427 REGS_ENTRYPOINT(FT_Exit20) { FT_Exit(context, 20); }
 428 REGS_ENTRYPOINT(FT_Exit24) { FT_Exit(context, 24); }
 429 REGS_ENTRYPOINT(FT_Exit28) { FT_Exit(context, 28); }
 430 REGS_ENTRYPOINT(FT_Exit32) { FT_Exit(context, 32); }
 431 REGS_ENTRYPOINT(FT_Exit36) { FT_Exit(context, 36); }
 432 REGS_ENTRYPOINT(FT_Exit40) { FT_Exit(context, 40); }
 433 REGS_ENTRYPOINT(FT_Exit44) { FT_Exit(context, 44); }
 434 REGS_ENTRYPOINT(FT_Exit48) { FT_Exit(context, 48); }
 435 REGS_ENTRYPOINT(FT_Exit52) { FT_Exit(context, 52); }
 436 REGS_ENTRYPOINT(FT_Exit56) { FT_Exit(context, 56); }
 437
 438
 439 /**********************************************************************
 440  *           WOWCallback16 (KERNEL32.62)(WOW32.2)
 441  * Calls a win16 function with a single DWORD argument.
 442  * RETURNS
 443  *      the return value
 444  */
 445 DWORD WINAPI WOWCallback16(
 446         FARPROC16 fproc,        /* [in] win16 function to call */
 447         DWORD arg               /* [in] single DWORD argument to function */
 448 ) {
 449         DWORD   ret;
 450         TRACE(thunk,"(%p,0x%08lx)...\n",fproc,arg);
 451         ret =  Callbacks->CallWOWCallbackProc(fproc,arg);
 452         TRACE(thunk,"... returns %ld\n",ret);
 453         return ret;
 454 }
 455
 456 /**********************************************************************
 457  *           WOWCallback16Ex (KERNEL32.55)(WOW32.3)
 458  * Calls a function in 16bit code.
 459  * RETURNS
 460  *      TRUE for success
 461  */
 462 BOOL32 WINAPI WOWCallback16Ex(
 463         FARPROC16 vpfn16,       /* [in] win16 function to call */
 464         DWORD dwFlags,          /* [in] flags */
 465         DWORD cbArgs,           /* [in] nr of arguments */
 466         LPVOID pArgs,           /* [in] pointer to arguments (LPDWORD) */
 467         LPDWORD pdwRetCode      /* [out] return value of win16 function */
 468 ) {
 469         return Callbacks->CallWOWCallback16Ex(vpfn16,dwFlags,cbArgs,pArgs,pdwRetCode);
 470 }
 471
 472 /***********************************************************************
 473  *              ThunkInitLS     (KERNEL32.43)
 474  * A thunkbuffer link routine
 475  * The thunkbuf looks like:
 476  *
 477  *      00: DWORD       length          ? don't know exactly
 478  *      04: SEGPTR      ptr             ? where does it point to?
 479  * The pointer ptr is written into the first DWORD of 'thunk'.
 480  * (probably correct implemented)
 481  * [ok probably]
 482  * RETURNS
 483  *      segmented pointer to thunk?
 484  */
 485 DWORD WINAPI ThunkInitLS(
 486         LPDWORD thunk,  /* [in] win32 thunk */
 487         LPCSTR thkbuf,  /* [in] thkbuffer name in win16 dll */
 488         DWORD len,      /* [in] thkbuffer length */
 489         LPCSTR dll16,   /* [in] name of win16 dll */
 490         LPCSTR dll32    /* [in] name of win32 dll (FIXME: not used?) */
 491 ) {
 492         HINSTANCE16     hmod;
 493         LPDWORD         addr;
 494         SEGPTR          segaddr;
 495
 496         hmod = LoadLibrary16(dll16);
 497         if (hmod<32) {
 498                 WARN(thunk,"failed to load 16bit DLL %s, error %d\n",
 499                              dll16,hmod);
 500                 return 0;
 501         }
 502         segaddr = (DWORD)WIN32_GetProcAddress16(hmod,(LPSTR)thkbuf);
 503         if (!segaddr) {
 504                 WARN(thunk,"no %s exported from %s!\n",thkbuf,dll16);
 505                 return 0;
 506         }
 507         addr = (LPDWORD)PTR_SEG_TO_LIN(segaddr);
 508         if (addr[0] != len) {
 509                 WARN(thunk,"thkbuf length mismatch? %ld vs %ld\n",len,addr[0]);
 510                 return 0;
 511         }
 512         if (!addr[1])
 513                 return 0;
 514         *(DWORD*)thunk = addr[1];
 515
 516         TRACE(thunk, "loaded module %d, func %s (%d) @ %p (%p), returning %p\n",
 517                      hmod, HIWORD(thkbuf)==0 ? "<ordinal>" : thkbuf, (int)thkbuf,
 518                      (void*)segaddr, addr, (void*)addr[1]);
 519
 520         return addr[1];
 521 }
 522
 523 /***********************************************************************
 524  *              Common32ThkLS   (KERNEL32.45)
 525  *
 526  * This is another 32->16 thunk, independent of the QT_Thunk/FT_Thunk
 527  * style thunks. The basic difference is that the parameter conversion
 528  * is done completely on the *16-bit* side here. Thus we do not call
 529  * the 16-bit target directly, but call a common entry point instead.
 530  * This entry function then calls the target according to the target
 531  * number passed in the DI register.
 532  *
 533  * Input:  EAX    SEGPTR to the common 16-bit entry point
 534  *         CX     offset in thunk table (target number * 4)
 535  *         DX     error return value if execution fails (unclear???)
 536  *         EDX.HI number of DWORD parameters
 537  *
 538  * (Note that we need to move the thunk table offset from CX to DI !)
 539  *
 540  * The called 16-bit stub expects its stack to look like this:
 541  *     ...
 542  *   (esp+40)  32-bit arguments
 543  *     ...
 544  *   (esp+8)   32 byte of stack space available as buffer
 545  *   (esp)     8 byte return address for use with 0x66 lret
 546  *
 547  * The called 16-bit stub uses a 0x66 lret to return to 32-bit code,
 548  * and uses the EAX register to return a DWORD return value.
 549  * Thus we need to use a special assembly glue routine
 550  * (CallRegisterLongProc instead of CallRegisterShortProc).
 551  *
 552  * Finally, we return to the caller, popping the arguments off
 553  * the stack.
 554  *
 555  * FIXME: The called function uses EBX to return the number of
 556  *        arguments that are to be popped off the caller's stack.
 557  *        This is clobbered by the assembly glue, so we simply use
 558  *        the original EDX.HI to get the number of arguments.
 559  *        (Those two values should be equal anyway ...?)
 560  *
 561  */
 562 REGS_ENTRYPOINT(Common32ThkLS)
 563 {
 564     CONTEXT context16;
 565     DWORD argsize;
 566     THDB *thdb = THREAD_Current();
 567
 568     memcpy(&context16,context,sizeof(context16));
 569
 570     DI_reg(&context16)  = CX_reg(context);
 571     CS_reg(&context16)  = HIWORD(EAX_reg(context));
 572     IP_reg(&context16)  = LOWORD(EAX_reg(context));
 573     EBP_reg(&context16) = OFFSETOF( thdb->cur_stack )
 574                            + (WORD)&((STACK16FRAME*)0)->bp;
 575
 576     argsize = HIWORD(EDX_reg(context)) * 4;
 577
 578     memcpy( ((LPBYTE)THREAD_STACK16(thdb))-argsize,
 579             (LPBYTE)ESP_reg(context)+4, argsize );
 580
 581     EAX_reg(context) = Callbacks->CallRegisterLongProc(&context16, argsize + 32);
 582
 583     /* Clean up caller's stack frame */
 584
 585     EIP_reg(context) = STACK32_POP(context);
 586     ESP_reg(context) += argsize;
 587     STACK32_PUSH(context, EIP_reg(context));
 588 }
 589
 590 /***********************************************************************
 591  *              OT_32ThkLSF     (KERNEL32.40)
 592  *
 593  * YET Another 32->16 thunk. The difference to Common32ThkLS is that
 594  * argument processing is done on both the 32-bit and the 16-bit side:
 595  * The 32-bit side prepares arguments, copying them onto the stack.
 596  *
 597  * When this routine is called, the first word on the stack is the
 598  * number of argument bytes prepared by the 32-bit code, and EDX
 599  * contains the 16-bit target address.
 600  *
 601  * The called 16-bit routine is another relaycode, doing further
 602  * argument processing and then calling the real 16-bit target
 603  * whose address is stored at [bp-04].
 604  *
 605  * The call proceeds using a normal CallRegisterShortProc.
 606  * After return from the 16-bit relaycode, the arguments need
 607  * to be copied *back* to the 32-bit stack, since the 32-bit
 608  * relaycode processes output parameters.
 609  *
 610  * Note that we copy twice the number of arguments, since some of the
 611  * 16-bit relaycodes in SYSTHUNK.DLL directly access the original
 612  * arguments of the caller!
 613  *
 614  * (Note that this function seems only to be used for
 615  *  OLECLI32 -> OLECLI and OLESVR32 -> OLESVR thunking.)
 616  */
 617 REGS_ENTRYPOINT(OT_32ThkLSF)
 618 {
 619     CONTEXT context16;
 620     DWORD argsize;
 621     THDB *thdb = THREAD_Current();
 622
 623     memcpy(&context16,context,sizeof(context16));
 624
 625     CS_reg(&context16)  = HIWORD(EDX_reg(context));
 626     IP_reg(&context16)  = LOWORD(EDX_reg(context));
 627     EBP_reg(&context16) = OFFSETOF( thdb->cur_stack )
 628                            + (WORD)&((STACK16FRAME*)0)->bp;
 629
 630     argsize = 2 * *(WORD *)(ESP_reg(context) + 4) + 2;
 631
 632     memcpy( ((LPBYTE)THREAD_STACK16(thdb))-argsize,
 633             (LPBYTE)ESP_reg(context)+4, argsize );
 634
 635     EAX_reg(context) = Callbacks->CallRegisterShortProc(&context16, argsize);
 636
 637     memcpy( (LPBYTE)ESP_reg(context)+4,
 638             ((LPBYTE)THREAD_STACK16(thdb))-argsize, argsize );
 639 }
 640
 641 /***********************************************************************
 642  *              ThunkInitLSF            (KERNEL32.41)
 643  * A thunk setup routine.
 644  * Expects a pointer to a preinitialized thunkbuffer in the first argument
 645  * looking like:
 646  *      00..03:         unknown (pointer, check _41, _43, _46)
 647  *      04: EB1E                jmp +0x20
 648  *
 649  *      06..23:         unknown (space for replacement code, check .90)
 650  *
 651  *      24:>E800000000          call offset 29
 652  *      29:>58                  pop eax            ( target of call )
 653  *      2A: 2D25000000          sub eax,0x00000025 ( now points to offset 4 )
 654  *      2F: BAxxxxxxxx          mov edx,xxxxxxxx
 655  *      34: 68yyyyyyyy          push KERNEL32.90
 656  *      39: C3                  ret
 657  *
 658  *      3A: EB1E                jmp +0x20
 659  *      3E ... 59:      unknown (space for replacement code?)
 660  *      5A: E8xxxxxxxx          call <32bitoffset xxxxxxxx>
 661  *      5F: 5A                  pop edx
 662  *      60: 81EA25xxxxxx        sub edx, 0x25xxxxxx
 663  *      66: 52                  push edx
 664  *      67: 68xxxxxxxx          push xxxxxxxx
 665  *      6C: 68yyyyyyyy          push KERNEL32.89
 666  *      71: C3                  ret
 667  *      72: end?
 668  * This function checks if the code is there, and replaces the yyyyyyyy entries
 669  * by the functionpointers.
 670  * The thunkbuf looks like:
 671  *
 672  *      00: DWORD       length          ? don't know exactly
 673  *      04: SEGPTR      ptr             ? where does it point to?
 674  * The segpointer ptr is written into the first DWORD of 'thunk'.
 675  * [ok probably]
 676  * RETURNS
 677  *      unclear, pointer to win16 thkbuffer?
 678  */
 679 LPVOID WINAPI ThunkInitLSF(
 680         LPBYTE thunk,   /* [in] win32 thunk */
 681         LPCSTR thkbuf,  /* [in] thkbuffer name in win16 dll */
 682         DWORD len,      /* [in] length of thkbuffer */
 683         LPCSTR dll16,   /* [in] name of win16 dll */
 684         LPCSTR dll32    /* [in] name of win32 dll */
 685 ) {
 686         HMODULE32       hkrnl32 = GetModuleHandle32A("KERNEL32");
 687         HMODULE16       hmod;
 688         LPDWORD         addr,addr2;
 689         DWORD           segaddr;
 690
 691         /* FIXME: add checks for valid code ... */
 692         /* write pointers to kernel32.89 and kernel32.90 (+ordinal base of 1) */
 693         *(DWORD*)(thunk+0x35) = (DWORD)GetProcAddress32(hkrnl32,(LPSTR)90);
 694         *(DWORD*)(thunk+0x6D) = (DWORD)GetProcAddress32(hkrnl32,(LPSTR)89);
 695
 696
 697         hmod = LoadLibrary16(dll16);
 698         if (hmod<32) {
 699                 ERR(thunk,"failed to load 16bit DLL %s, error %d\n",
 700                              dll16,hmod);
 701                 return NULL;
 702         }
 703         segaddr = (DWORD)WIN32_GetProcAddress16(hmod,(LPSTR)thkbuf);
 704         if (!segaddr) {
 705                 ERR(thunk,"no %s exported from %s!\n",thkbuf,dll16);
 706                 return NULL;
 707         }
 708         addr = (LPDWORD)PTR_SEG_TO_LIN(segaddr);
 709         if (addr[0] != len) {
 710                 ERR(thunk,"thkbuf length mismatch? %ld vs %ld\n",len,addr[0]);
 711                 return NULL;
 712         }
 713         addr2 = PTR_SEG_TO_LIN(addr[1]);
 714         if (HIWORD(addr2))
 715                 *(DWORD*)thunk = (DWORD)addr2;
 716
 717         TRACE(thunk, "loaded module %d, func %s(%d) @ %p (%p), returning %p\n",
 718                       hmod, HIWORD(thkbuf)==0 ? "<ordinal>" : thkbuf, (int)thkbuf,
 719                      (void*)segaddr, addr, addr2);
 720
 721         return addr2;
 722 }
 723
 724 /***********************************************************************
 725  *              FT_PrologPrime                  (KERNEL32.89)
 726  *
 727  * This function is called from the relay code installed by
 728  * ThunkInitLSF. It replaces the location from where it was
 729  * called by a standard FT_Prolog call stub (which is 'primed'
 730  * by inserting the correct target table pointer).
 731  * Finally, it calls that stub.
 732  *
 733  * Input:  ECX    target number + flags (passed through to FT_Prolog)
 734  *        (ESP)   offset of location where target table pointer
 735  *                is stored, relative to the start of the relay code
 736  *        (ESP+4) pointer to start of relay code
 737  *                (this is where the FT_Prolog call stub gets written to)
 738  *
 739  * Note: The two DWORD arguments get popped from the stack.
 740  *
 741  */
 742 REGS_ENTRYPOINT(FT_PrologPrime)
 743 {
 744     DWORD  targetTableOffset = STACK32_POP(context);
 745     LPBYTE relayCode = (LPBYTE)STACK32_POP(context);
 746     DWORD *targetTable = *(DWORD **)(relayCode+targetTableOffset);
 747     DWORD  targetNr = LOBYTE(ECX_reg(context));
 748
 749     _write_ftprolog(relayCode, targetTable);
 750
 751     /* We should actually call the relay code now, */
 752     /* but we skip it and go directly to FT_Prolog */
 753     EDX_reg(context) = targetTable[targetNr];
 754     __regs_FT_Prolog(context);
 755 }
 756
 757 /***********************************************************************
 758  *              QT_ThunkPrime                   (KERNEL32.90)
 759  *
 760  * This function corresponds to FT_PrologPrime, but installs a
 761  * call stub for QT_Thunk instead.
 762  *
 763  * Input: (EBP-4) target number (passed through to QT_Thunk)
 764  *         EDX    target table pointer location offset
 765  *         EAX    start of relay code
 766  *
 767  */
 768 REGS_ENTRYPOINT(QT_ThunkPrime)
 769 {
 770     DWORD  targetTableOffset = EDX_reg(context);
 771     LPBYTE relayCode = (LPBYTE)EAX_reg(context);
 772     DWORD *targetTable = *(DWORD **)(relayCode+targetTableOffset);
 773     DWORD  targetNr = LOBYTE(*(DWORD *)(EBP_reg(context) - 4));
 774
 775     _write_qtthunk(relayCode, targetTable);
 776
 777     /* We should actually call the relay code now, */
 778     /* but we skip it and go directly to QT_Thunk */
 779     EDX_reg(context) = targetTable[targetNr];
 780     __regs_QT_Thunk(context);
 781 }
 782
 783 /***********************************************************************
 784  *                                                      (KERNEL32.46)
 785  * Another thunkbuf link routine.
 786  * The start of the thunkbuf looks like this:
 787  *      00: DWORD       length
 788  *      04: SEGPTR      address for thunkbuffer pointer
 789  * [ok probably]
 790  */
 791 VOID WINAPI ThunkInitSL(
 792         LPBYTE thunk,           /* [in] start of thunkbuffer */
 793         LPCSTR thkbuf,          /* [in] name/ordinal of thunkbuffer in win16 dll */
 794         DWORD len,              /* [in] length of thunkbuffer */
 795         LPCSTR dll16,           /* [in] name of win16 dll containing the thkbuf */
 796         LPCSTR dll32            /* [in] win32 dll. FIXME: strange, unused */
 797 ) {
 798         LPDWORD         addr;
 799         HMODULE16       hmod;
 800         SEGPTR          segaddr;
 801
 802         hmod = LoadLibrary16(dll16);
 803         if (hmod < 32) {
 804                 ERR(thunk,"couldn't load %s, error %d\n",dll16,hmod);
 805                 return;
 806         }
 807         segaddr = (SEGPTR)WIN32_GetProcAddress16(hmod,(LPSTR)thkbuf);
 808         if (!segaddr) {
 809                 ERR(thunk,"haven't found %s in %s!\n",thkbuf,dll16);
 810                 return;
 811         }
 812         addr = (LPDWORD)PTR_SEG_TO_LIN(segaddr);
 813         if (addr[0] != len) {
 814                 ERR(thunk,"length of thkbuf differs from expected length! "
 815                              "(%ld vs %ld)\n",addr[0],len);
 816                 return;
 817         }
 818         *(DWORD*)PTR_SEG_TO_LIN(addr[1]) = (DWORD)thunk;
 819
 820         TRACE(thunk, "loaded module %d, func %s(%d) @ %p (%p)\n",
 821                      hmod, HIWORD(thkbuf)==0 ? "<ordinal>" : thkbuf,
 822                      (int)thkbuf, (void*)segaddr, addr);
 823 }
 824
 825 /**********************************************************************
 826  *           SSInit             KERNEL.700
 827  * RETURNS
 828  *      TRUE for success.
 829  */
 830 BOOL32 WINAPI SSInit()
 831 {
 832     return TRUE;
 833 }
 834
 835 /**********************************************************************
 836  *           SSOnBigStack       KERNEL32.87
 837  * Check if thunking is initialized (ss selector set up etc.)
 838  * We do that differently, so just return TRUE.
 839  * [ok]
 840  * RETURNS
 841  *      TRUE for success.
 842  */
 843 BOOL32 WINAPI SSOnBigStack()
 844 {
 845     TRACE(thunk, "Yes, thunking is initialized\n");
 846     return TRUE;
 847 }
 848
 849 /**********************************************************************
 850  *           SSCall
 851  * One of the real thunking functions. This one seems to be for 32<->32
 852  * thunks. It should probably be capable of crossing processboundaries.
 853  *
 854  * And YES, I've seen nr=48 (somewhere in the Win95 32<->16 OLE coupling)
 855  * [ok]
 856  */
 857 DWORD WINAPIV SSCall(
 858         DWORD nr,       /* [in] number of argument bytes */
 859         DWORD flags,    /* [in] FIXME: flags ? */
 860         FARPROC32 fun,  /* [in] function to call */
 861         ...             /* [in/out] arguments */
 862 ) {
 863     DWORD i,ret;
 864     DWORD *args = ((DWORD *)&fun) + 1;
 865
 866     if(TRACE_ON(thunk)){
 867       dbg_decl_str(thunk, 256);
 868       for (i=0;i<nr/4;i++)
 869         dsprintf(thunk,"0x%08lx,",args[i]);
 870       TRACE(thunk,"(%ld,0x%08lx,%p,[%s])\n",
 871                     nr,flags,fun,dbg_str(thunk));
 872     }
 873     switch (nr) {
 874     case 0:     ret = fun();
 875                 break;
 876     case 4:     ret = fun(args[0]);
 877                 break;
 878     case 8:     ret = fun(args[0],args[1]);
 879                 break;
 880     case 12:    ret = fun(args[0],args[1],args[2]);
 881                 break;
 882     case 16:    ret = fun(args[0],args[1],args[2],args[3]);
 883                 break;
 884     case 20:    ret = fun(args[0],args[1],args[2],args[3],args[4]);
 885                 break;
 886     case 24:    ret = fun(args[0],args[1],args[2],args[3],args[4],args[5]);
 887                 break;
 888     case 28:    ret = fun(args[0],args[1],args[2],args[3],args[4],args[5],args[6]);
 889                 break;
 890     case 32:    ret = fun(args[0],args[1],args[2],args[3],args[4],args[5],args[6],args[7]);
 891                 break;
 892     case 36:    ret = fun(args[0],args[1],args[2],args[3],args[4],args[5],args[6],args[7],args[8]);
 893                 break;
 894     case 40:    ret = fun(args[0],args[1],args[2],args[3],args[4],args[5],args[6],args[7],args[8],args[9]);
 895                 break;
 896     case 44:    ret = fun(args[0],args[1],args[2],args[3],args[4],args[5],args[6],args[7],args[8],args[9],args[10]);
 897                 break;
 898     case 48:    ret = fun(args[0],args[1],args[2],args[3],args[4],args[5],args[6],args[7],args[8],args[9],args[10],args[11]);
 899                 break;
 900     default:
 901         WARN(thunk,"Unsupported nr of arguments, %ld\n",nr);
 902         ret = 0;
 903         break;
 904
 905     }
 906     TRACE(thunk," returning %ld ...\n",ret);
 907     return ret;
 908 }
 909
 910 /**********************************************************************
 911  *              InitCBClient            (KERNEL.623)
 912  */
 913 WORD WINAPI InitCBClient(DWORD x)
 914 {
 915     FIXME(thunk,"(0x%08lx): stub\n",x);
 916     return TRUE;
 917 }
 918
 919 /**********************************************************************
 920  *              RegisterCBClient        (KERNEL.619)
 921  * Seems to store y and z depending on x in some internal lists...
 922  */
 923 WORD WINAPI RegisterCBClient(WORD x,DWORD y,DWORD z)
 924 {
 925     FIXME(thunk,"(0x%04x,0x%08lx,0x%08lx): stub\n",x,y,z);
 926     return x;
 927 }
 928
 929 /**********************************************************************
 930  *              KERNEL_607              (KERNEL)
 931  */
 932 LPVOID WINAPI _KERNEL_607(SEGPTR target, LPVOID relay, DWORD dummy)
 933 {
 934     TDB *pTask = (TDB*)GlobalLock16(GetCurrentTask());
 935     LPBYTE thunk = HeapAlloc( GetProcessHeap(), 0, 22 ), x = thunk;
 936
 937     *x++=0x90; *x++=0x68; *((DWORD*)x)++=(DWORD)relay;  /* nop; pushl relay */
 938     *x++=0x90; *x++=0x68; *((DWORD*)x)++=(DWORD)target; /* nop; pushl target */
 939     *x++=0x90; *x++=0x58;                               /* nop; popl eax */
 940     *x++=0xC3;                                          /* ret */
 941     *x++=0xCC; *x++=0xCC;
 942     *x++=0x01;                                          /* type: LS */
 943     *((WORD *)x)++ = pTask->hInstance;                  /* owner */
 944     *((WORD *)x)++ = 0;                                 /* next */
 945
 946     return thunk;
 947 }
 948
 949 /**********************************************************************
 950  *              KERNEL_608              (KERNEL)
 951  */
 952 SEGPTR WINAPI _KERNEL_608(LPVOID target, SEGPTR relay, DWORD dummy)
 953 {
 954     TDB *pTask = (TDB*)GlobalLock16(GetCurrentTask());
 955     LPBYTE thunk = HeapAlloc( GetProcessHeap(), 0, 22 ), x = thunk;
 956     WORD sel;
 957
 958     *x++=0x66; *x++=0x68; *((DWORD*)x)++=(DWORD)relay;  /* pushl relay */
 959     *x++=0x66; *x++=0x68; *((DWORD*)x)++=(DWORD)target; /* pushl target */
 960     *x++=0x66; *x++=0x58;                               /* popl eax */
 961     *x++=0xCB;                                          /* ret */
 962     *x++=0xCC; *x++=0xCC;
 963     *x++=0x02;                                          /* type: SL */
 964     *((WORD *)x)++ = pTask->hInstance;                  /* owner */
 965     *((WORD *)x)++ = 0;                                 /* next */
 966
 967     sel = SELECTOR_AllocBlock( thunk, 22, SEGMENT_CODE, FALSE, FALSE );
 968     return PTR_SEG_OFF_TO_SEGPTR( sel, 0 );
 969 }
 970
 971 /**********************************************************************
 972  *              KERNEL_611              (KERNEL)
 973  */
 974 VOID WINAPI _KERNEL_611(DWORD relay, DWORD target)
 975 {
 976 }
 977
 978 /**********************************************************************
 979  *              KERNEL_612              (KERNEL)
 980  */
 981 BOOL16 WINAPI _KERNEL_612(LPBYTE target)
 982 {
 983     return    target[ 0] == 0x66 && target[ 1] == 0x68
 984            && target[ 6] == 0x66 && target[ 2] == 0x68
 985            && target[12] == 0x66 && target[13] == 0x58
 986            && target[14] == 0xCB;
 987 }
 988
 989 /**********************************************************************
 990  *                      AllocSLCallback         (KERNEL32)
 991  *
 992  * Win95 uses some structchains for callbacks. It allocates them
 993  * in blocks of 100 entries, size 32 bytes each, layout:
 994  * blockstart:
 995  *      0:      PTR     nextblockstart
 996  *      4:      entry   *first;
 997  *      8:      WORD    sel ( start points to blockstart)
 998  *      A:      WORD    unknown
 999  * 100xentry:
1000  *      00..17:         Code
1001  *      18:     PDB     *owning_process;
1002  *      1C:     PTR     blockstart
1003  *
1004  * We ignore this for now. (Just a note for further developers)
1005  * FIXME: use this method, so we don't waste selectors...
1006  *
1007  * Following code is then generated by AllocSLCallback. The code is 16 bit, so
1008  * the 0x66 prefix switches from word->long registers.
1009  *
1010  *      665A            pop     edx
1011  *      6668x arg2 x    pushl   <arg2>
1012  *      6652            push    edx
1013  *      EAx arg1 x      jmpf    <arg1>
1014  *
1015  * returns the startaddress of this thunk.
1016  *
1017  * Note, that they look very similair to the ones allocates by THUNK_Alloc.
1018  * RETURNS
1019  *      segmented pointer to the start of the thunk
1020  */
1021 DWORD WINAPI
1022 AllocSLCallback(
1023         DWORD finalizer,        /* [in] finalizer function */
1024         DWORD callback          /* [in] callback function */
1025 ) {
1026         LPBYTE  x,thunk = HeapAlloc( GetProcessHeap(), 0, 32 );
1027         WORD    sel;
1028
1029         x=thunk;
1030         *x++=0x66;*x++=0x5a;                            /* popl edx */
1031         *x++=0x66;*x++=0x68;*(DWORD*)x=finalizer;x+=4;  /* pushl finalizer */
1032         *x++=0x66;*x++=0x52;                            /* pushl edx */
1033         *x++=0xea;*(DWORD*)x=callback;x+=4;             /* jmpf callback */
1034
1035         *(PDB32**)(thunk+18) = PROCESS_Current();
1036
1037         sel = SELECTOR_AllocBlock( thunk , 32, SEGMENT_CODE, FALSE, FALSE );
1038         return (sel<<16)|0;
1039 }
1040
1041 /**********************************************************************
1042  *              FreeSLCallback          (KERNEL32.274)
1043  * Frees the specified 16->32 callback
1044  */
1045 void WINAPI
1046 FreeSLCallback(
1047         DWORD x /* [in] 16 bit callback (segmented pointer?) */
1048 ) {
1049         FIXME(win32,"(0x%08lx): stub\n",x);
1050 }
1051
1052
1053 /**********************************************************************
1054  *              GetTEBSelectorFS        (KERNEL.475)
1055  *      Set the 16-bit %fs to the 32-bit %fs (current TEB selector)
1056  */
1057 VOID WINAPI GetTEBSelectorFS( CONTEXT *context )
1058 {
1059     GET_FS( FS_reg(context) );
1060 }
1061
1062 /**********************************************************************
1063  *              KERNEL_431              (KERNEL.431)
1064  *              IsPeFormat              (W32SYS.2)
1065  * Checks the passed filename if it is a PE format executeable
1066  * RETURNS
1067  *  TRUE, if it is.
1068  *  FALSE if not.
1069  */
1070 BOOL16 WINAPI IsPeFormat(
1071         LPSTR   fn,     /* [in] filename to executeable */
1072         HFILE16 hf16    /* [in] open file, if filename is NULL */
1073 ) {
1074         IMAGE_DOS_HEADER        mzh;
1075         HFILE32                 hf=HFILE16_TO_HFILE32(hf16);
1076         OFSTRUCT                ofs;
1077         DWORD                   xmagic;
1078
1079         if (fn) {
1080                 hf = OpenFile32(fn,&ofs,OF_READ);
1081                 if (hf==HFILE_ERROR32)
1082                         return FALSE;
1083         }
1084         _llseek32(hf,0,SEEK_SET);
1085         if (sizeof(mzh)!=_lread32(hf,&mzh,sizeof(mzh))) {
1086                 _lclose32(hf);
1087                 return FALSE;
1088         }
1089         if (mzh.e_magic!=IMAGE_DOS_SIGNATURE) {
1090                 WARN(dosmem,"File has not got dos signature!\n");
1091                 _lclose32(hf);
1092                 return FALSE;
1093         }
1094         _llseek32(hf,mzh.e_lfanew,SEEK_SET);
1095         if (sizeof(DWORD)!=_lread32(hf,&xmagic,sizeof(DWORD))) {
1096                 _lclose32(hf);
1097                 return FALSE;
1098         }
1099         _lclose32(hf);
1100         return (xmagic == IMAGE_NT_SIGNATURE);
1101 }
1102
1103 /***********************************************************************
1104  *           WOWHandle32                        (KERNEL32.57)(WOW32.16)
1105  * Converts a win16 handle of type into the respective win32 handle.
1106  * We currently just return this handle, since most handles are the same
1107  * for win16 and win32.
1108  * RETURNS
1109  *      The new handle
1110  */
1111 HANDLE32 WINAPI WOWHandle32(
1112         WORD handle,            /* [in] win16 handle */
1113         WOW_HANDLE_TYPE type    /* [in] handle type */
1114 ) {
1115         TRACE(win32,"(0x%04x,%d)\n",handle,type);
1116         return (HANDLE32)handle;
1117 }
1118
1119 /***********************************************************************
1120  *           K32Thk1632Prolog                   (KERNEL32.492)
1121  */
1122 REGS_ENTRYPOINT(K32Thk1632Prolog)
1123 {
1124    LPBYTE code = (LPBYTE)EIP_reg(context) - 5;
1125
1126    /* Arrrgh! SYSTHUNK.DLL just has to re-implement another method
1127       of 16->32 thunks instead of using one of the standard methods!
1128       This means that SYSTHUNK.DLL itself switches to a 32-bit stack,
1129       and does a far call to the 32-bit code segment of OLECLI32/OLESVR32.
1130       Unfortunately, our CallTo/CallFrom mechanism is therefore completely
1131       bypassed, which means it will crash the next time the 32-bit OLE
1132       code thunks down again to 16-bit (this *will* happen!).
1133
1134       The following hack tries to recognize this situation.
1135       This is possible since the called stubs in OLECLI32/OLESVR32 all
1136       look exactly the same:
1137         00   E8xxxxxxxx    call K32Thk1632Prolog
1138         05   FF55FC        call [ebp-04]
1139         08   E8xxxxxxxx    call K32Thk1632Epilog
1140         0D   66CB          retf
1141
1142       If we recognize this situation, we try to simulate the actions
1143       of our CallTo/CallFrom mechanism by copying the 16-bit stack
1144       to our 32-bit stack, creating a proper STACK16FRAME and
1145       updating thdb->cur_stack. */
1146
1147    if (   code[5] == 0xFF && code[6] == 0x55 && code[7] == 0xFC
1148        && code[13] == 0x66 && code[14] == 0xCB)
1149    {
1150       WORD  stackSel  = NtCurrentTeb()->stack_sel;
1151       DWORD stackBase = GetSelectorBase(stackSel);
1152
1153       THDB *thdb = THREAD_Current();
1154       DWORD argSize = EBP_reg(context) - ESP_reg(context);
1155       char *stack16 = (char *)ESP_reg(context);
1156       char *stack32 = (char *)thdb->cur_stack - argSize;
1157       STACK16FRAME *frame16 = (STACK16FRAME *)stack16 - 1;
1158
1159       TRACE(thunk, "before SYSTHUNK hack: EBP: %08lx ESP: %08lx cur_stack: %08lx\n",
1160                    EBP_reg(context), ESP_reg(context), thdb->cur_stack);
1161
1162       memset(frame16, '\0', sizeof(STACK16FRAME));
1163       frame16->frame32 = (STACK32FRAME *)thdb->cur_stack;
1164       frame16->ebp = EBP_reg(context);
1165
1166       memcpy(stack32, stack16, argSize);
1167       thdb->cur_stack = PTR_SEG_OFF_TO_SEGPTR(stackSel, (DWORD)frame16 - stackBase);
1168
1169       ESP_reg(context) = (DWORD)stack32;
1170       EBP_reg(context) = ESP_reg(context) + argSize;
1171
1172       TRACE(thunk, "after  SYSTHUNK hack: EBP: %08lx ESP: %08lx cur_stack: %08lx\n",
1173                    EBP_reg(context), ESP_reg(context), thdb->cur_stack);
1174    }
1175
1176    SYSLEVEL_ReleaseWin16Lock();
1177 }
1178
1179 /***********************************************************************
1180  *           K32Thk1632Epilog                   (KERNEL32.491)
1181  */
1182 REGS_ENTRYPOINT(K32Thk1632Epilog)
1183 {
1184    LPBYTE code = (LPBYTE)EIP_reg(context) - 13;
1185
1186    SYSLEVEL_RestoreWin16Lock();
1187
1188    /* We undo the SYSTHUNK hack if necessary. See K32Thk1632Prolog. */
1189
1190    if (   code[5] == 0xFF && code[6] == 0x55 && code[7] == 0xFC
1191        && code[13] == 0x66 && code[14] == 0xCB)
1192    {
1193       THDB *thdb = THREAD_Current();
1194       STACK16FRAME *frame16 = (STACK16FRAME *)PTR_SEG_TO_LIN(thdb->cur_stack);
1195       char *stack16 = (char *)(frame16 + 1);
1196       DWORD argSize = frame16->ebp - (DWORD)stack16;
1197       char *stack32 = (char *)frame16->frame32 - argSize;
1198
1199       DWORD nArgsPopped = ESP_reg(context) - (DWORD)stack32;
1200
1201       TRACE(thunk, "before SYSTHUNK hack: EBP: %08lx ESP: %08lx cur_stack: %08lx\n",
1202                    EBP_reg(context), ESP_reg(context), thdb->cur_stack);
1203
1204       thdb->cur_stack = (DWORD)frame16->frame32;
1205
1206       ESP_reg(context) = (DWORD)stack16 + nArgsPopped;
1207       EBP_reg(context) = frame16->ebp;
1208
1209       TRACE(thunk, "after  SYSTHUNK hack: EBP: %08lx ESP: %08lx cur_stack: %08lx\n",
1210                    EBP_reg(context), ESP_reg(context), thdb->cur_stack);
1211    }
1212 }
1213