dlls/winedos/module.c

   1 /*
   2  * DOS (MZ) loader
   3  *
   4  * Copyright 1998 Ove Kåven
   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  * Note: This code hasn't been completely cleaned up yet.
  21  */
  22
  23 #include "config.h"
  24 #include "wine/port.h"
  25
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <errno.h>
  30 #include <fcntl.h>
  31 #include <signal.h>
  32 #ifdef HAVE_UNISTD_H
  33 # include <unistd.h>
  34 #endif
  35 #include <sys/types.h>
  36 #include <sys/stat.h>
  37 #ifdef HAVE_SYS_TIME_H
  38 # include <sys/time.h>
  39 #endif
  40 #include "windef.h"
  41 #include "wine/winbase16.h"
  42 #include "wingdi.h"
  43 #include "winuser.h"
  44 #include "winerror.h"
  45 #include "module.h"
  46 #include "task.h"
  47 #include "file.h"
  48 #include "miscemu.h"
  49 #include "wine/debug.h"
  50 #include "dosexe.h"
  51 #include "dosvm.h"
  52 #include "vga.h"
  53
  54 WINE_DEFAULT_DEBUG_CHANNEL(module);
  55
  56 static BOOL DOSVM_isdosexe;
  57
  58 /**********************************************************************
  59  *          DOSVM_IsWin16
  60  *
  61  * Return TRUE if we are in Windows process.
  62  */
  63 BOOL DOSVM_IsWin16(void)
  64 {
  65   return DOSVM_isdosexe ? FALSE : TRUE;
  66 }
  67
  68 #ifdef MZ_SUPPORTED
  69
  70 #ifdef HAVE_SYS_MMAN_H
  71 # include <sys/mman.h>
  72 #endif
  73
  74 /* define this to try mapping through /proc/pid/mem instead of a temp file,
  75    but Linus doesn't like mmapping /proc/pid/mem, so it doesn't work for me */
  76 #undef MZ_MAPSELF
  77
  78 #define BIOS_DATA_SEGMENT 0x40
  79 #define PSP_SIZE 0x10
  80
  81 #define SEG16(ptr,seg) ((LPVOID)((BYTE*)ptr+((DWORD)(seg)<<4)))
  82 #define SEGPTR16(ptr,segptr) ((LPVOID)((BYTE*)ptr+((DWORD)SELECTOROF(segptr)<<4)+OFFSETOF(segptr)))
  83
  84 /* structures for EXEC */
  85
  86 typedef struct {
  87   WORD env_seg;
  88   DWORD cmdline WINE_PACKED;
  89   DWORD fcb1 WINE_PACKED;
  90   DWORD fcb2 WINE_PACKED;
  91   WORD init_sp;
  92   WORD init_ss;
  93   WORD init_ip;
  94   WORD init_cs;
  95 } ExecBlock;
  96
  97 typedef struct {
  98   WORD load_seg;
  99   WORD rel_seg;
 100 } OverlayBlock;
 101
 102 /* global variables */
 103
 104 pid_t dosvm_pid;
 105
 106 static WORD init_cs,init_ip,init_ss,init_sp;
 107 static HANDLE dosvm_thread, loop_thread;
 108 static DWORD dosvm_tid, loop_tid;
 109
 110 static void MZ_Launch(void);
 111 static BOOL MZ_InitTask(void);
 112
 113 static void MZ_CreatePSP( LPVOID lpPSP, WORD env, WORD par )
 114 {
 115   PDB16*psp=lpPSP;
 116
 117   psp->int20=0x20CD; /* int 20 */
 118   /* some programs use this to calculate how much memory they need */
 119   psp->nextParagraph=0x9FFF; /* FIXME: use a real value */
 120   /* FIXME: dispatcher */
 121   psp->savedint22 = DOSVM_GetRMHandler(0x22);
 122   psp->savedint23 = DOSVM_GetRMHandler(0x23);
 123   psp->savedint24 = DOSVM_GetRMHandler(0x24);
 124   psp->parentPSP=par;
 125   psp->environment=env;
 126   /* FIXME: more PSP stuff */
 127 }
 128
 129 static void MZ_FillPSP( LPVOID lpPSP, LPBYTE cmdline, int length )
 130 {
 131   PDB16      *psp = lpPSP;
 132
 133   while(length > 0 && *cmdline != ' ') {
 134     length--;
 135     cmdline++;
 136   }
 137
 138   /* command.com does not skip over multiple spaces */
 139
 140   if(length > 126) {
 141     ERR("Command line truncated! (length %d > maximum length 126)\n",
 142        length);
 143     length = 126;
 144   }
 145
 146   psp->cmdLine[0] = length;
 147   if(length > 0)
 148     memmove(psp->cmdLine+1, cmdline, length);
 149   psp->cmdLine[length+1] = '\r';
 150
 151   /* FIXME: more PSP stuff */
 152 }
 153
 154 /* default INT 08 handler: increases timer tick counter but not much more */
 155 static char int08[]={
 156  0xCD,0x1C,           /* int $0x1c */
 157  0x50,                /* pushw %ax */
 158  0x1E,                /* pushw %ds */
 159  0xB8,0x40,0x00,      /* movw $0x40,%ax */
 160  0x8E,0xD8,           /* movw %ax,%ds */
 161 #if 0
 162  0x83,0x06,0x6C,0x00,0x01, /* addw $1,(0x6c) */
 163  0x83,0x16,0x6E,0x00,0x00, /* adcw $0,(0x6e) */
 164 #else
 165  0x66,0xFF,0x06,0x6C,0x00, /* incl (0x6c) */
 166 #endif
 167  0xB0,0x20,           /* movb $0x20,%al */
 168  0xE6,0x20,           /* outb %al,$0x20 */
 169  0x1F,                /* popw %ax */
 170  0x58,                /* popw %ax */
 171  0xCF                 /* iret */
 172 };
 173
 174 static void MZ_InitHandlers(void)
 175 {
 176  WORD seg;
 177  LPBYTE start=DOSMEM_GetBlock(sizeof(int08),&seg);
 178  memcpy(start,int08,sizeof(int08));
 179 /* INT 08: point it at our tick-incrementing handler */
 180  ((SEGPTR*)0)[0x08]=MAKESEGPTR(seg,0);
 181 /* INT 1C: just point it to IRET, we don't want to handle it ourselves */
 182  ((SEGPTR*)0)[0x1C]=MAKESEGPTR(seg,sizeof(int08)-1);
 183 }
 184
 185 static WORD MZ_InitEnvironment( LPCSTR env, LPCSTR name )
 186 {
 187  unsigned sz=0;
 188  WORD seg;
 189  LPSTR envblk;
 190
 191  if (env) {
 192   /* get size of environment block */
 193   while (env[sz++]) sz+=strlen(env+sz)+1;
 194  } else sz++;
 195  /* allocate it */
 196  envblk=DOSMEM_GetBlock(sz+sizeof(WORD)+strlen(name)+1,&seg);
 197  /* fill it */
 198  if (env) {
 199   memcpy(envblk,env,sz);
 200  } else envblk[0]=0;
 201  /* DOS 3.x: the block contains 1 additional string */
 202  *(WORD*)(envblk+sz)=1;
 203  /* being the program name itself */
 204  strcpy(envblk+sz+sizeof(WORD),name);
 205  return seg;
 206 }
 207
 208 static BOOL MZ_InitMemory(void)
 209 {
 210     /* initialize the memory */
 211     TRACE("Initializing DOS memory structures\n");
 212     DOSMEM_Init(TRUE);
 213     DOSDEV_InstallDOSDevices();
 214
 215     MZ_InitHandlers();
 216     return TRUE;
 217 }
 218
 219 static BOOL MZ_DoLoadImage( HANDLE hFile, LPCSTR filename, OverlayBlock *oblk )
 220 {
 221   IMAGE_DOS_HEADER mz_header;
 222   DWORD image_start,image_size,min_size,max_size,avail;
 223   BYTE*psp_start,*load_start,*oldenv;
 224   int x, old_com=0, alloc;
 225   SEGPTR reloc;
 226   WORD env_seg, load_seg, rel_seg, oldpsp_seg;
 227   DWORD len;
 228
 229   if (DOSVM_psp) {
 230     /* DOS process already running, inherit from it */
 231     PDB16* par_psp = (PDB16*)((DWORD)DOSVM_psp << 4);
 232     alloc=0;
 233     oldenv = (LPBYTE)((DWORD)par_psp->environment << 4);
 234     oldpsp_seg = DOSVM_psp;
 235   } else {
 236     /* allocate new DOS process, inheriting from Wine environment */
 237     alloc=1;
 238     oldenv = GetEnvironmentStringsA();
 239     oldpsp_seg = 0;
 240   }
 241
 242  SetFilePointer(hFile,0,NULL,FILE_BEGIN);
 243  if (   !ReadFile(hFile,&mz_header,sizeof(mz_header),&len,NULL)
 244      || len != sizeof(mz_header)
 245      || mz_header.e_magic != IMAGE_DOS_SIGNATURE) {
 246   char *p = strrchr( filename, '.' );
 247   if (!p || strcasecmp( p, ".com" ))  /* check for .COM extension */
 248   {
 249       SetLastError(ERROR_BAD_FORMAT);
 250       goto load_error;
 251   }
 252   old_com=1; /* assume .COM file */
 253   image_start=0;
 254   image_size=GetFileSize(hFile,NULL);
 255   min_size=0x10000; max_size=0x100000;
 256   mz_header.e_crlc=0;
 257   mz_header.e_ss=0; mz_header.e_sp=0xFFFE;
 258   mz_header.e_cs=0; mz_header.e_ip=0x100;
 259  } else {
 260   /* calculate load size */
 261   image_start=mz_header.e_cparhdr<<4;
 262   image_size=mz_header.e_cp<<9; /* pages are 512 bytes */
 263   if ((mz_header.e_cblp!=0)&&(mz_header.e_cblp!=4)) image_size-=512-mz_header.e_cblp;
 264   image_size-=image_start;
 265   min_size=image_size+((DWORD)mz_header.e_minalloc<<4)+(PSP_SIZE<<4);
 266   max_size=image_size+((DWORD)mz_header.e_maxalloc<<4)+(PSP_SIZE<<4);
 267  }
 268
 269   if (alloc) MZ_InitMemory();
 270
 271   if (oblk) {
 272     /* load overlay into preallocated memory */
 273     load_seg=oblk->load_seg;
 274     rel_seg=oblk->rel_seg;
 275     load_start=(LPBYTE)((DWORD)load_seg<<4);
 276   } else {
 277     /* allocate environment block */
 278     env_seg=MZ_InitEnvironment(oldenv, filename);
 279
 280     /* allocate memory for the executable */
 281     TRACE("Allocating DOS memory (min=%ld, max=%ld)\n",min_size,max_size);
 282     avail=DOSMEM_Available();
 283     if (avail<min_size) {
 284       ERR("insufficient DOS memory\n");
 285       SetLastError(ERROR_NOT_ENOUGH_MEMORY);
 286       goto load_error;
 287     }
 288     if (avail>max_size) avail=max_size;
 289     psp_start=DOSMEM_GetBlock(avail,&DOSVM_psp);
 290     if (!psp_start) {
 291       ERR("error allocating DOS memory\n");
 292       SetLastError(ERROR_NOT_ENOUGH_MEMORY);
 293       goto load_error;
 294     }
 295     load_seg=DOSVM_psp+(old_com?0:PSP_SIZE);
 296     rel_seg=load_seg;
 297     load_start=psp_start+(PSP_SIZE<<4);
 298     MZ_CreatePSP(psp_start, env_seg, oldpsp_seg);
 299   }
 300
 301  /* load executable image */
 302  TRACE("loading DOS %s image, %08lx bytes\n",old_com?"COM":"EXE",image_size);
 303  SetFilePointer(hFile,image_start,NULL,FILE_BEGIN);
 304  if (!ReadFile(hFile,load_start,image_size,&len,NULL) || len != image_size) {
 305   SetLastError(ERROR_BAD_FORMAT);
 306   goto load_error;
 307  }
 308
 309  if (mz_header.e_crlc) {
 310   /* load relocation table */
 311   TRACE("loading DOS EXE relocation table, %d entries\n",mz_header.e_crlc);
 312   /* FIXME: is this too slow without read buffering? */
 313   SetFilePointer(hFile,mz_header.e_lfarlc,NULL,FILE_BEGIN);
 314   for (x=0; x<mz_header.e_crlc; x++) {
 315    if (!ReadFile(hFile,&reloc,sizeof(reloc),&len,NULL) || len != sizeof(reloc)) {
 316     SetLastError(ERROR_BAD_FORMAT);
 317     goto load_error;
 318    }
 319    *(WORD*)SEGPTR16(load_start,reloc)+=rel_seg;
 320   }
 321  }
 322
 323   if (!oblk) {
 324     init_cs = load_seg+mz_header.e_cs;
 325     init_ip = mz_header.e_ip;
 326     init_ss = load_seg+mz_header.e_ss;
 327     init_sp = mz_header.e_sp;
 328
 329     TRACE("entry point: %04x:%04x\n",init_cs,init_ip);
 330   }
 331
 332   if (alloc && !MZ_InitTask()) {
 333     SetLastError(ERROR_GEN_FAILURE);
 334     return FALSE;
 335   }
 336
 337   return TRUE;
 338
 339 load_error:
 340   DOSVM_psp = oldpsp_seg;
 341
 342   return FALSE;
 343 }
 344
 345 /***********************************************************************
 346  *              LoadDosExe (WINEDOS.@)
 347  *
 348  * Called from Wine loader when a new real-mode DOS process is started.
 349  * Loads DOS program into memory and executes the program.
 350  */
 351 void WINAPI MZ_LoadImage( LPCSTR filename, HANDLE hFile )
 352 {
 353   DOSVM_isdosexe = TRUE;
 354   if (MZ_DoLoadImage( hFile, filename, NULL )) MZ_Launch();
 355 }
 356
 357 /***********************************************************************
 358  *              MZ_Exec
 359  *
 360  * this may only be called from existing DOS processes
 361  */
 362 BOOL WINAPI MZ_Exec( CONTEXT86 *context, LPCSTR filename, BYTE func, LPVOID paramblk )
 363 {
 364   DWORD binType;
 365   STARTUPINFOA st;
 366   PROCESS_INFORMATION pe;
 367   HANDLE hFile;
 368
 369   BOOL ret = FALSE;
 370
 371   if(!GetBinaryTypeA(filename, &binType))   /* determine what kind of binary this is */
 372   {
 373     return FALSE; /* binary is not an executable */
 374   }
 375
 376   /* handle non-dos executables */
 377   if(binType != SCS_DOS_BINARY)
 378   {
 379     if(func == 0) /* load and execute */
 380     {
 381       LPBYTE fullCmdLine;
 382       WORD fullCmdLength;
 383       LPBYTE psp_start = (LPBYTE)((DWORD)DOSVM_psp << 4);
 384       PDB16 *psp = (PDB16 *)psp_start;
 385       ExecBlock *blk = (ExecBlock *)paramblk;
 386       LPBYTE cmdline = PTR_REAL_TO_LIN(SELECTOROF(blk->cmdline),OFFSETOF(blk->cmdline));
 387       LPBYTE envblock = PTR_REAL_TO_LIN(psp->environment, 0);
 388       BYTE cmdLength = cmdline[0];
 389
 390       fullCmdLength = (strlen(filename) + 1) + cmdLength + 1; /* filename + space + cmdline + terminating null character */
 391
 392       fullCmdLine = HeapAlloc(GetProcessHeap(), 0, fullCmdLength);
 393       if(!fullCmdLine) return FALSE; /* return false on memory alloc failure */
 394
 395       /* build the full command line from the executable file and the command line being passed in */
 396       snprintf(fullCmdLine, fullCmdLength, "%s ", filename); /* start off with the executable filename and a space */
 397       memcpy(fullCmdLine + strlen(fullCmdLine), cmdline + 1, cmdLength); /* append cmdline onto the end */
 398       fullCmdLine[fullCmdLength - 1] = 0; /* null terminate string */
 399
 400       ZeroMemory (&st, sizeof(STARTUPINFOA));
 401       st.cb = sizeof(STARTUPINFOA);
 402       ret = CreateProcessA (NULL, fullCmdLine, NULL, NULL, TRUE, 0, envblock, NULL, &st, &pe);
 403
 404       /* wait for the app to finish and clean up PROCESS_INFORMATION handles */
 405       if(ret)
 406       {
 407         WaitForSingleObject(pe.hProcess, INFINITE);  /* wait here until the child process is complete */
 408         CloseHandle(pe.hProcess);
 409         CloseHandle(pe.hThread);
 410       }
 411
 412       HeapFree(GetProcessHeap(), 0, fullCmdLine);  /* free the memory we allocated */
 413     }
 414     else
 415     {
 416       FIXME("EXEC type of %d not implemented for non-dos executables\n", func);
 417       ret = FALSE;
 418     }
 419
 420     return ret;
 421   } /* if(binType != SCS_DOS_BINARY) */
 422
 423
 424   /* handle dos executables */
 425
 426   hFile = CreateFileA( filename, GENERIC_READ, FILE_SHARE_READ,
 427                              NULL, OPEN_EXISTING, 0, 0);
 428   if (hFile == INVALID_HANDLE_VALUE) return FALSE;
 429
 430   switch (func) {
 431   case 0: /* load and execute */
 432   case 1: /* load but don't execute */
 433     {
 434       /* save current process's return SS:SP now */
 435       LPBYTE psp_start = (LPBYTE)((DWORD)DOSVM_psp << 4);
 436       PDB16 *psp = (PDB16 *)psp_start;
 437       psp->saveStack = (DWORD)MAKESEGPTR(context->SegSs, LOWORD(context->Esp));
 438     }
 439     ret = MZ_DoLoadImage( hFile, filename, NULL );
 440     if (ret) {
 441       /* MZ_LoadImage created a new PSP and loaded new values into it,
 442        * let's work on the new values now */
 443       LPBYTE psp_start = (LPBYTE)((DWORD)DOSVM_psp << 4);
 444       ExecBlock *blk = (ExecBlock *)paramblk;
 445       LPBYTE cmdline = PTR_REAL_TO_LIN(SELECTOROF(blk->cmdline),OFFSETOF(blk->cmdline));
 446
 447       /* First character contains the length of the command line. */
 448       MZ_FillPSP(psp_start, cmdline + 1, cmdline[0]);
 449
 450       /* the lame MS-DOS engineers decided that the return address should be in int22 */
 451       DOSVM_SetRMHandler(0x22, (FARPROC16)MAKESEGPTR(context->SegCs, LOWORD(context->Eip)));
 452       if (func) {
 453         /* don't execute, just return startup state */
 454         blk->init_cs = init_cs;
 455         blk->init_ip = init_ip;
 456         blk->init_ss = init_ss;
 457         blk->init_sp = init_sp;
 458       } else {
 459         /* execute by making us return to new process */
 460         context->SegCs = init_cs;
 461         context->Eip   = init_ip;
 462         context->SegSs = init_ss;
 463         context->Esp   = init_sp;
 464         context->SegDs = DOSVM_psp;
 465         context->SegEs = DOSVM_psp;
 466         context->Eax   = 0;
 467       }
 468     }
 469     break;
 470   case 3: /* load overlay */
 471     {
 472       OverlayBlock *blk = (OverlayBlock *)paramblk;
 473       ret = MZ_DoLoadImage( hFile, filename, blk );
 474     }
 475     break;
 476   default:
 477     FIXME("EXEC load type %d not implemented\n", func);
 478     SetLastError(ERROR_INVALID_FUNCTION);
 479     break;
 480   }
 481   CloseHandle(hFile);
 482   return ret;
 483 }
 484
 485 /***********************************************************************
 486  *              MZ_AllocDPMITask
 487  */
 488 void WINAPI MZ_AllocDPMITask( void )
 489 {
 490   MZ_InitMemory();
 491   MZ_InitTask();
 492 }
 493
 494 /***********************************************************************
 495  *              MZ_RunInThread
 496  */
 497 void WINAPI MZ_RunInThread( PAPCFUNC proc, ULONG_PTR arg )
 498 {
 499   if (loop_thread) {
 500     DOS_SPC spc;
 501     HANDLE event;
 502
 503     spc.proc = proc;
 504     spc.arg = arg;
 505     event = CreateEventA(NULL, TRUE, FALSE, NULL);
 506     PostThreadMessageA(loop_tid, WM_USER, (WPARAM)event, (LPARAM)&spc);
 507     WaitForSingleObject(event, INFINITE);
 508     CloseHandle(event);
 509   } else
 510     proc(arg);
 511 }
 512
 513 static DWORD WINAPI MZ_DOSVM( LPVOID lpExtra )
 514 {
 515   CONTEXT context;
 516   DWORD ret;
 517
 518   dosvm_pid = getpid();
 519
 520   memset( &context, 0, sizeof(context) );
 521   context.SegCs  = init_cs;
 522   context.Eip    = init_ip;
 523   context.SegSs  = init_ss;
 524   context.Esp    = init_sp;
 525   context.SegDs  = DOSVM_psp;
 526   context.SegEs  = DOSVM_psp;
 527   context.EFlags = 0x00080000;  /* virtual interrupt flag */
 528   DOSVM_SetTimer(0x10000);
 529   ret = DOSVM_Enter( &context );
 530
 531   dosvm_pid = 0;
 532   return ret;
 533 }
 534
 535 static BOOL MZ_InitTask(void)
 536 {
 537   if (!DuplicateHandle(GetCurrentProcess(), GetCurrentThread(),
 538                        GetCurrentProcess(), &loop_thread,
 539                        0, FALSE, DUPLICATE_SAME_ACCESS))
 540     return FALSE;
 541   dosvm_thread = CreateThread(NULL, 0, MZ_DOSVM, NULL, CREATE_SUSPENDED, &dosvm_tid);
 542   if (!dosvm_thread) {
 543     CloseHandle(loop_thread);
 544     loop_thread = 0;
 545     return FALSE;
 546   }
 547   loop_tid = GetCurrentThreadId();
 548   return TRUE;
 549 }
 550
 551 static void MZ_Launch(void)
 552 {
 553   TDB *pTask = GlobalLock16( GetCurrentTask() );
 554   BYTE *psp_start = PTR_REAL_TO_LIN( DOSVM_psp, 0 );
 555   LPSTR cmdline = GetCommandLineA();
 556   DWORD rv;
 557   SYSLEVEL *lock;
 558
 559   MZ_FillPSP(psp_start, cmdline, cmdline ? strlen(cmdline) : 0);
 560   pTask->flags |= TDBF_WINOLDAP;
 561
 562   GetpWin16Lock( &lock );
 563   _LeaveSysLevel( lock );
 564
 565   ResumeThread(dosvm_thread);
 566   rv = DOSVM_Loop(dosvm_thread);
 567
 568   CloseHandle(dosvm_thread);
 569   dosvm_thread = 0; dosvm_tid = 0;
 570   CloseHandle(loop_thread);
 571   loop_thread = 0; loop_tid = 0;
 572
 573   VGA_Clean();
 574   ExitThread(rv);
 575 }
 576
 577 /***********************************************************************
 578  *              MZ_Exit
 579  */
 580 void WINAPI MZ_Exit( CONTEXT86 *context, BOOL cs_psp, WORD retval )
 581 {
 582   if (DOSVM_psp) {
 583     WORD psp_seg = cs_psp ? context->SegCs : DOSVM_psp;
 584     LPBYTE psp_start = (LPBYTE)((DWORD)psp_seg << 4);
 585     PDB16 *psp = (PDB16 *)psp_start;
 586     WORD parpsp = psp->parentPSP; /* check for parent DOS process */
 587     if (parpsp) {
 588       /* retrieve parent's return address */
 589       FARPROC16 retaddr = DOSVM_GetRMHandler(0x22);
 590       /* restore interrupts */
 591       DOSVM_SetRMHandler(0x22, psp->savedint22);
 592       DOSVM_SetRMHandler(0x23, psp->savedint23);
 593       DOSVM_SetRMHandler(0x24, psp->savedint24);
 594       /* FIXME: deallocate file handles etc */
 595       /* free process's associated memory
 596        * FIXME: walk memory and deallocate all blocks owned by process */
 597       DOSMEM_FreeBlock( PTR_REAL_TO_LIN(psp->environment,0) );
 598       DOSMEM_FreeBlock( PTR_REAL_TO_LIN(DOSVM_psp,0) );
 599       /* switch to parent's PSP */
 600       DOSVM_psp = parpsp;
 601       psp_start = (LPBYTE)((DWORD)parpsp << 4);
 602       psp = (PDB16 *)psp_start;
 603       /* now return to parent */
 604       DOSVM_retval = retval;
 605       context->SegCs = SELECTOROF(retaddr);
 606       context->Eip   = OFFSETOF(retaddr);
 607       context->SegSs = SELECTOROF(psp->saveStack);
 608       context->Esp   = OFFSETOF(psp->saveStack);
 609       return;
 610     } else
 611       TRACE("killing DOS task\n");
 612   }
 613   ExitThread( retval );
 614 }
 615
 616
 617 /***********************************************************************
 618  *              MZ_Current
 619  */
 620 BOOL WINAPI MZ_Current( void )
 621 {
 622   return (dosvm_pid != 0); /* FIXME: do a better check */
 623 }
 624
 625 #else /* !MZ_SUPPORTED */
 626
 627 /***********************************************************************
 628  *              LoadDosExe (WINEDOS.@)
 629  */
 630 void WINAPI MZ_LoadImage( LPCSTR filename, HANDLE hFile )
 631 {
 632   WARN("DOS executables not supported on this platform\n");
 633   SetLastError(ERROR_BAD_FORMAT);
 634 }
 635
 636 /***********************************************************************
 637  *              MZ_Exec
 638  */
 639 BOOL WINAPI MZ_Exec( CONTEXT86 *context, LPCSTR filename, BYTE func, LPVOID paramblk )
 640 {
 641   /* can't happen */
 642   SetLastError(ERROR_BAD_FORMAT);
 643   return FALSE;
 644 }
 645
 646 /***********************************************************************
 647  *              MZ_AllocDPMITask
 648  */
 649 void WINAPI MZ_AllocDPMITask( void )
 650 {
 651     ERR("Actual real-mode calls not supported on this platform!\n");
 652 }
 653
 654 /***********************************************************************
 655  *              MZ_RunInThread
 656  */
 657 void WINAPI MZ_RunInThread( PAPCFUNC proc, ULONG_PTR arg )
 658 {
 659     proc(arg);
 660 }
 661
 662 /***********************************************************************
 663  *              MZ_Exit
 664  */
 665 void WINAPI MZ_Exit( CONTEXT86 *context, BOOL cs_psp, WORD retval )
 666 {
 667   ExitThread( retval );
 668 }
 669
 670 /***********************************************************************
 671  *              MZ_Current
 672  */
 673 BOOL WINAPI MZ_Current( void )
 674 {
 675     return FALSE;
 676 }
 677
 678 #endif /* !MZ_SUPPORTED */