loader/task.c

   1 /*
   2  * Task functions
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  */
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include "windows.h"
  11 #include "task.h"
  12 #include "callback.h"
  13 #include "dos_fs.h"
  14 #include "debugger.h"
  15 #include "global.h"
  16 #include "instance.h"
  17 #include "message.h"
  18 #include "miscemu.h"
  19 #include "module.h"
  20 #include "neexe.h"
  21 #include "options.h"
  22 #include "selectors.h"
  23 #include "toolhelp.h"
  24 #include "stddebug.h"
  25 #include "debug.h"
  26 #include "dde_proc.h"
  27
  28   /* Min. number of thunks allocated when creating a new segment */
  29 #define MIN_THUNKS  32
  30
  31   /* 32-bit stack size for each task */
  32   /* Must not be greater than 64k, or MAKE_SEGPTR won't work */
  33 #define STACK32_SIZE 0x10000
  34
  35 /* ------ Internal variables ------ */
  36
  37 static HTASK hFirstTask = 0;
  38 static HTASK hCurrentTask = 0;
  39 static HTASK hTaskToKill = 0;
  40 static HTASK hLockedTask = 0;
  41 static WORD nTaskCount = 0;
  42 static HANDLE hDOSEnvironment = 0;
  43
  44 /* ------ Internal declarations ------ */
  45
  46   /* TASK_Reschedule() 16-bit entry point */
  47 static FARPROC TASK_RescheduleProc;
  48
  49 #ifdef WINELIB
  50 #define TASK_SCHEDULE()  TASK_Reschedule();
  51 #else
  52 #define TASK_SCHEDULE()  CallTo16_word_(TASK_RescheduleProc,0)
  53 #endif
  54
  55 static HANDLE TASK_CreateDOSEnvironment(void);
  56
  57 /***********************************************************************
  58  *           TASK_Init
  59  */
  60 BOOL TASK_Init(void)
  61 {
  62     TASK_RescheduleProc = (FARPROC)GetWndProcEntry16( "TASK_Reschedule" );
  63     if (!(hDOSEnvironment = TASK_CreateDOSEnvironment()))
  64         fprintf( stderr, "Not enough memory for DOS Environment\n" );
  65     return (hDOSEnvironment != 0);
  66 }
  67
  68
  69 /***********************************************************************
  70  *           TASK_CreateDOSEnvironment
  71  *
  72  * Create the original DOS environment.
  73  */
  74 static HANDLE TASK_CreateDOSEnvironment(void)
  75 {
  76     static const char program_name[] = "KRNL386.EXE";
  77     char **e, *p;
  78     int initial_size, size;
  79     HANDLE handle;
  80
  81     extern char **environ;
  82     extern char WindowsDirectory[], SystemDirectory[];
  83
  84     /* DOS environment format:
  85      * ASCIIZ   string 1
  86      * ASCIIZ   string 2
  87      * ...
  88      * ASCIIZ   string n
  89      * ASCIIZ   PATH=xxx
  90      * ASCIIZ   windir=xxx
  91      * BYTE     0
  92      * WORD     1
  93      * ASCIIZ   program name (e.g. C:\WINDOWS\SYSTEM\KRNL386.EXE)
  94      */
  95
  96     /* First compute the size of the fixed part of the environment */
  97
  98     initial_size = 5 +                            /* PATH= */
  99                    strlen(WindowsPath) + 1 +      /* path value */
 100                    7 +                            /* windir= */
 101                    strlen(WindowsDirectory) + 1 + /* windir value */
 102                    1 +                            /* BYTE 0 at end */
 103                    sizeof(WORD) +                 /* WORD 1 */
 104                    strlen(SystemDirectory) + 1 +  /* program directory */
 105                    strlen(program_name) + 1;      /* program name */
 106
 107     /* Compute the total size of the Unix environment (except path) */
 108
 109     for (e = environ, size = initial_size; *e; e++)
 110     {
 111         if (strncasecmp(*e, "path=", 5))
 112         {
 113             int len = strlen(*e) + 1;
 114             if (size + len >= 32767)
 115             {
 116                 fprintf( stderr, "Warning: environment larger than 32k.\n" );
 117                 break;
 118             }
 119             size += len;
 120         }
 121     }
 122
 123
 124     /* Now allocate the environment */
 125
 126     if (!(handle = GlobalAlloc( GMEM_FIXED, size ))) return 0;
 127     p = (char *)GlobalLock( handle );
 128
 129     /* And fill it with the Unix environment */
 130
 131     for (e = environ, size = initial_size; *e; e++)
 132     {
 133         if (strncasecmp(*e, "path=", 5))
 134         {
 135             int len = strlen(*e) + 1;
 136             if (size + len >= 32767) break;
 137             strcpy( p, *e );
 138             size += len;
 139             p    += len;
 140         }
 141     }
 142
 143     /* Now add the path and Windows directory */
 144
 145     strcpy( p, "PATH=" );
 146     strcat( p, WindowsPath );
 147     p += strlen(p) + 1;
 148
 149     strcpy( p, "windir=" );
 150     strcat( p, WindowsDirectory );
 151     p += strlen(p) + 1;
 152
 153     /* Now add the program name */
 154
 155     *p++ = '\0';
 156     *(WORD *)p = 1;
 157     p += sizeof(WORD);
 158     strcpy( p, SystemDirectory );
 159     strcat( p, "\\" );
 160     strcat( p, program_name );
 161
 162     /* Display it */
 163
 164     p = (char *) GlobalLock( handle );
 165     dprintf_task(stddeb, "Master DOS environment at %p\n", p);
 166     for (; *p; p += strlen(p) + 1) dprintf_task(stddeb, "    %s\n", p);
 167     dprintf_task( stddeb, "Progname: %s\n", p+3 );
 168
 169     return handle;
 170 }
 171
 172
 173 /***********************************************************************
 174  *           TASK_LinkTask
 175  */
 176 static void TASK_LinkTask( HTASK hTask )
 177 {
 178     HTASK *prevTask;
 179     TDB *pTask;
 180
 181     if (!(pTask = (TDB *)GlobalLock( hTask ))) return;
 182     prevTask = &hFirstTask;
 183     while (*prevTask)
 184     {
 185         TDB *prevTaskPtr = (TDB *)GlobalLock( *prevTask );
 186         if (prevTaskPtr->priority >= pTask->priority) break;
 187         prevTask = &prevTaskPtr->hNext;
 188     }
 189     pTask->hNext = *prevTask;
 190     *prevTask = hTask;
 191     nTaskCount++;
 192 }
 193
 194
 195 /***********************************************************************
 196  *           TASK_UnlinkTask
 197  */
 198 static void TASK_UnlinkTask( HTASK hTask )
 199 {
 200     HTASK *prevTask;
 201     TDB *pTask;
 202
 203     prevTask = &hFirstTask;
 204     while (*prevTask && (*prevTask != hTask))
 205     {
 206         pTask = (TDB *)GlobalLock( *prevTask );
 207         prevTask = &pTask->hNext;
 208     }
 209     if (*prevTask)
 210     {
 211         pTask = (TDB *)GlobalLock( *prevTask );
 212         *prevTask = pTask->hNext;
 213         pTask->hNext = 0;
 214         nTaskCount--;
 215     }
 216 }
 217
 218
 219 /***********************************************************************
 220  *           TASK_CreateThunks
 221  *
 222  * Create a thunk free-list in segment 'handle', starting from offset 'offset'
 223  * and containing 'count' entries.
 224  */
 225 static void TASK_CreateThunks( HGLOBAL handle, WORD offset, WORD count )
 226 {
 227     int i;
 228     WORD free;
 229     THUNKS *pThunk;
 230
 231     pThunk = (THUNKS *)((BYTE *)GlobalLock( handle ) + offset);
 232     pThunk->next = 0;
 233     pThunk->magic = THUNK_MAGIC;
 234     pThunk->free = (int)&pThunk->thunks - (int)pThunk;
 235     free = pThunk->free;
 236     for (i = 0; i < count-1; i++)
 237     {
 238         free += 8;  /* Offset of next thunk */
 239         pThunk->thunks[4*i] = free;
 240     }
 241     pThunk->thunks[4*i] = 0;  /* Last thunk */
 242 }
 243
 244
 245 /***********************************************************************
 246  *           TASK_AllocThunk
 247  *
 248  * Allocate a thunk for MakeProcInstance().
 249  */
 250 static SEGPTR TASK_AllocThunk( HTASK hTask )
 251 {
 252     TDB *pTask;
 253     THUNKS *pThunk;
 254     WORD sel, base;
 255
 256     if (!(pTask = (TDB *)GlobalLock( hTask ))) return 0;
 257     sel = pTask->hCSAlias;
 258     pThunk = &pTask->thunks;
 259     base = (int)pThunk - (int)pTask;
 260     while (!pThunk->free)
 261     {
 262         sel = pThunk->next;
 263         if (!sel)  /* Allocate a new segment */
 264         {
 265             sel = GLOBAL_Alloc( GMEM_FIXED, sizeof(THUNKS) + (MIN_THUNKS-1)*8,
 266                                 pTask->hPDB, TRUE, FALSE, FALSE );
 267             if (!sel) return (SEGPTR)0;
 268             TASK_CreateThunks( sel, 0, MIN_THUNKS );
 269             pThunk->next = sel;
 270         }
 271         pThunk = (THUNKS *)GlobalLock( sel );
 272         base = 0;
 273     }
 274     base += pThunk->free;
 275     pThunk->free = *(WORD *)((BYTE *)pThunk + pThunk->free);
 276     return MAKELONG( base, sel );
 277 }
 278
 279
 280 /***********************************************************************
 281  *           TASK_FreeThunk
 282  *
 283  * Free a MakeProcInstance() thunk.
 284  */
 285 static BOOL TASK_FreeThunk( HTASK hTask, SEGPTR thunk )
 286 {
 287     TDB *pTask;
 288     THUNKS *pThunk;
 289     WORD sel, base;
 290
 291     if (!(pTask = (TDB *)GlobalLock( hTask ))) return 0;
 292     sel = pTask->hCSAlias;
 293     pThunk = &pTask->thunks;
 294     base = (int)pThunk - (int)pTask;
 295     while (sel && (sel != HIWORD(thunk)))
 296     {
 297         sel = pThunk->next;
 298         pThunk = (THUNKS *)GlobalLock( sel );
 299         base = 0;
 300     }
 301     if (!sel) return FALSE;
 302     *(WORD *)((BYTE *)pThunk + LOWORD(thunk) - base) = pThunk->free;
 303     pThunk->free = LOWORD(thunk) - base;
 304     return TRUE;
 305 }
 306
 307
 308 /***********************************************************************
 309  *           TASK_CallToStart
 310  *
 311  * 32-bit entry point for a new task. This function is responsible for
 312  * setting up the registers and jumping to the 16-bit entry point.
 313  */
 314 #ifndef WINELIB
 315 static void TASK_CallToStart(void)
 316 {
 317     int cs_reg, ds_reg, ip_reg;
 318     TDB *pTask = (TDB *)GlobalLock( hCurrentTask );
 319     NE_MODULE *pModule = (NE_MODULE *)GlobalLock( pTask->hModule );
 320     SEGTABLEENTRY *pSegTable = NE_SEG_TABLE( pModule );
 321
 322     /* Registers at initialization must be:
 323      * ax   zero
 324      * bx   stack size in bytes
 325      * cx   heap size in bytes
 326      * si   previous app instance
 327      * di   current app instance
 328      * bp   zero
 329      * es   selector to the PSP
 330      * ds   dgroup of the application
 331      * ss   stack selector
 332      * sp   top of the stack
 333      */
 334
 335     cs_reg = pSegTable[pModule->cs - 1].selector;
 336     ip_reg = pModule->ip;
 337     ds_reg = pSegTable[pModule->dgroup - 1].selector;
 338 #ifndef WINELIB
 339 /* JBP: I doubt a CallTo16_regs_ is possible in libwine.a, and IF1632 is not
 340  *      allowed.
 341  */
 342     IF1632_Saved16_ss = pTask->ss;
 343     IF1632_Saved16_sp = pTask->sp;
 344     dprintf_task( stddeb, "Starting main program: cs:ip=%04x:%04x ds=%04x ss:sp=%04x:%04x\n",
 345                  cs_reg, ip_reg, ds_reg,
 346                  IF1632_Saved16_ss, IF1632_Saved16_sp);
 347
 348     CallTo16_regs_( (FARPROC)(cs_reg << 16 | ip_reg), ds_reg,
 349                    pTask->hPDB /*es*/, 0 /*bp*/, 0 /*ax*/,
 350                    pModule->stack_size /*bx*/, pModule->heap_size /*cx*/,
 351                    0 /*dx*/, 0 /*si*/, ds_reg /*di*/ );
 352 #else
 353     fprintf(stderr, "JBP: Ignoring main program: cs:ip=%04x:%04x ds=%04x ss:sp=%04x:%04x\n",
 354                  cs_reg, ip_reg, ds_reg,
 355                  pTask->ss, pTask->sp);
 356 #endif
 357     /* This should never return */
 358     fprintf( stderr, "TASK_CallToStart: Main program returned!\n" );
 359     TASK_KillCurrentTask( 1 );
 360 }
 361 #endif
 362
 363
 364 /***********************************************************************
 365  *           TASK_CreateTask
 366  */
 367 HTASK TASK_CreateTask( HMODULE hModule, HANDLE hInstance, HANDLE hPrevInstance,
 368                        HANDLE hEnvironment, char *cmdLine, WORD cmdShow )
 369 {
 370     HTASK hTask;
 371     TDB *pTask;
 372     HANDLE hParentEnv;
 373     NE_MODULE *pModule;
 374     SEGTABLEENTRY *pSegTable;
 375     LPSTR name;
 376     char filename[256];
 377 #ifndef WINELIB32
 378     char *stack16Top, *stack32Top;
 379     STACK16FRAME *frame16;
 380     STACK32FRAME *frame32;
 381     extern DWORD CALL16_RetAddr_word;
 382 #endif
 383
 384     if (!(pModule = (NE_MODULE *)GlobalLock( hModule ))) return 0;
 385     pSegTable = NE_SEG_TABLE( pModule );
 386
 387       /* Allocate the task structure */
 388
 389     hTask = GLOBAL_Alloc( GMEM_FIXED | GMEM_ZEROINIT, sizeof(TDB),
 390                           hModule, FALSE, FALSE, FALSE );
 391     if (!hTask) return 0;
 392     pTask = (TDB *)GlobalLock( hTask );
 393
 394       /* Allocate the new environment block */
 395
 396     if (!(hParentEnv = hEnvironment))
 397     {
 398         TDB *pParent = (TDB *)GlobalLock( hCurrentTask );
 399         hParentEnv = pParent ? pParent->pdb.environment : hDOSEnvironment;
 400     }
 401     /* FIXME: do we really need to make a copy also when */
 402     /*        we don't use the parent environment? */
 403     if (!(hEnvironment = GlobalAlloc( GMEM_FIXED, GlobalSize( hParentEnv ) )))
 404     {
 405         GlobalFree( hTask );
 406         return 0;
 407     }
 408     memcpy( GlobalLock( hEnvironment ), GlobalLock( hParentEnv ),
 409             GlobalSize( hParentEnv ) );
 410
 411       /* Get current directory */
 412
 413     GetModuleFileName( hModule, filename, sizeof(filename) );
 414     name = strrchr(filename, '\\');
 415     if (name) *(name+1) = 0;
 416
 417       /* Fill the task structure */
 418
 419     pTask->nEvents       = 1;  /* So the task can be started */
 420     pTask->hSelf         = hTask;
 421     pTask->flags         = 0;
 422     pTask->version       = pModule->expected_version;
 423     pTask->hInstance     = hInstance;
 424     pTask->hPrevInstance = hPrevInstance;
 425     pTask->hModule       = hModule;
 426     pTask->hParent       = hCurrentTask;
 427 #ifdef WINELIB
 428     pTask->curdrive      = 'C' - 'A' + 0x80;
 429 #else
 430     pTask->curdrive      = filename[0] - 'A' + 0x80;
 431 #endif
 432     pTask->magic         = TDB_MAGIC;
 433     pTask->nCmdShow      = cmdShow;
 434     strcpy( pTask->curdir, filename+2 );
 435
 436       /* Create the thunks block */
 437
 438     TASK_CreateThunks( hTask, (int)&pTask->thunks - (int)pTask, 7 );
 439
 440       /* Copy the module name */
 441
 442     name = MODULE_GetModuleName( hModule );
 443     strncpy( pTask->module_name, name, sizeof(pTask->module_name) );
 444
 445       /* Fill the PDB */
 446
 447     pTask->pdb.int20 = 0x20cd;
 448     pTask->pdb.dispatcher[0] = 0x9a;  /* ljmp */
 449     *(DWORD *)&pTask->pdb.dispatcher[1] = MODULE_GetEntryPoint( GetModuleHandle("KERNEL"), 102 );  /* KERNEL.102 is DOS3Call() */
 450 #ifndef WINELIB
 451     pTask->pdb.savedint22 = INT_GetHandler( 0x22 );
 452     pTask->pdb.savedint23 = INT_GetHandler( 0x23 );
 453     pTask->pdb.savedint24 = INT_GetHandler( 0x24 );
 454 #endif
 455     pTask->pdb.environment = hEnvironment;
 456     strncpy( pTask->pdb.cmdLine + 1, cmdLine, 126 );
 457     pTask->pdb.cmdLine[127] = '\0';
 458     pTask->pdb.cmdLine[0] = strlen( pTask->pdb.cmdLine + 1 );
 459
 460       /* Get the compatibility flags */
 461
 462     pTask->compat_flags = GetProfileInt( name, "Compatibility", 0 );
 463
 464       /* Allocate a selector for the PDB */
 465
 466     pTask->hPDB = GLOBAL_CreateBlock( GMEM_FIXED, &pTask->pdb, sizeof(PDB),
 467                                       hModule, FALSE, FALSE, FALSE, NULL );
 468
 469       /* Allocate a code segment alias for the TDB */
 470
 471     pTask->hCSAlias = GLOBAL_CreateBlock( GMEM_FIXED, (void *)pTask,
 472                                           sizeof(TDB), pTask->hPDB, TRUE,
 473                                           FALSE, FALSE, NULL );
 474
 475       /* Set the owner of the environment block */
 476
 477     FarSetOwner( pTask->pdb.environment, pTask->hPDB );
 478
 479       /* Default DTA overwrites command-line */
 480
 481     pTask->dta = MAKELONG( (int)&pTask->pdb.cmdLine - (int)&pTask->pdb,
 482                            pTask->hPDB );
 483
 484       /* Allocate the 32-bit stack */
 485
 486 #ifndef WINELIB
 487     pTask->hStack32 = GLOBAL_Alloc( GMEM_FIXED, STACK32_SIZE, pTask->hPDB,
 488                                     FALSE, FALSE, FALSE );
 489
 490       /* Create the 32-bit stack frame */
 491
 492     *(DWORD *)GlobalLock(pTask->hStack32) = 0xDEADBEEF;
 493     stack32Top = (char*)GlobalLock(pTask->hStack32) + STACK32_SIZE;
 494     frame32 = (STACK32FRAME *)stack32Top - 1;
 495     frame32->saved_esp = (DWORD)stack32Top;
 496     frame32->edi = 0;
 497     frame32->esi = 0;
 498     frame32->edx = 0;
 499     frame32->ecx = 0;
 500     frame32->ebx = 0;
 501     frame32->ebp = 0;
 502     frame32->retaddr = (DWORD)TASK_CallToStart;
 503     frame32->codeselector = WINE_CODE_SELECTOR;
 504     pTask->esp = (DWORD)frame32;
 505
 506       /* Create the 16-bit stack frame */
 507
 508     pTask->ss = hInstance;
 509     pTask->sp = ((pModule->sp != 0) ? pModule->sp :
 510                  pSegTable[pModule->ss-1].minsize + pModule->stack_size) & ~1;
 511     stack16Top = (char *)PTR_SEG_OFF_TO_LIN( pTask->ss, pTask->sp );
 512     frame16 = (STACK16FRAME *)stack16Top - 1;
 513     frame16->saved_ss = 0; /*pTask->ss;*/
 514     frame16->saved_sp = 0; /*pTask->sp;*/
 515     frame16->ds = frame16->es = pTask->hInstance;
 516     frame16->entry_point = 0;
 517     frame16->ordinal_number = 24;  /* WINPROCS.24 is TASK_Reschedule */
 518     frame16->dll_id = 24; /* WINPROCS */
 519     frame16->bp = 0;
 520     frame16->ip = LOWORD( CALL16_RetAddr_word );
 521     frame16->cs = HIWORD( CALL16_RetAddr_word );
 522     pTask->sp -= sizeof(STACK16FRAME);
 523
 524       /* If there's no 16-bit stack yet, use a part of the new task stack */
 525       /* This is only needed to have a stack to switch from on the first  */
 526       /* call to DirectedYield(). */
 527
 528     if (!IF1632_Saved16_ss)
 529     {
 530         IF1632_Saved16_ss = pTask->ss;
 531         IF1632_Saved16_sp = pTask->sp;
 532     }
 533
 534       /* Add a breakpoint at the start of the task */
 535
 536     if (Options.debug)
 537     {
 538         DBG_ADDR addr = { pSegTable[pModule->cs-1].selector, pModule->ip };
 539         fprintf( stderr, "Task '%s': ", name );
 540         DEBUG_AddBreakpoint( &addr );
 541     }
 542 #endif
 543
 544       /* Add the task to the linked list */
 545
 546     TASK_LinkTask( hTask );
 547
 548     dprintf_task( stddeb, "CreateTask: module='%s' cmdline='%s' task="NPFMT"\n",
 549                   name, cmdLine, hTask );
 550
 551     return hTask;
 552 }
 553
 554
 555 /***********************************************************************
 556  *           TASK_DeleteTask
 557  */
 558 static void TASK_DeleteTask( HTASK hTask )
 559 {
 560     TDB *pTask;
 561
 562     if (!(pTask = (TDB *)GlobalLock( hTask ))) return;
 563
 564       /* Free the task module */
 565
 566     FreeModule( pTask->hModule );
 567
 568       /* Free all memory used by this task (including the 32-bit stack, */
 569       /* the environment block and the thunk segments). */
 570
 571     GlobalFreeAll( pTask->hPDB );
 572
 573       /* Free message queue */
 574
 575     MSG_DeleteMsgQueue( pTask->hQueue );
 576
 577       /* Free the selector aliases */
 578
 579     GLOBAL_FreeBlock( pTask->hCSAlias );
 580     GLOBAL_FreeBlock( pTask->hPDB );
 581
 582       /* Free the task structure itself */
 583
 584     GlobalFree( hTask );
 585 }
 586
 587
 588 /***********************************************************************
 589  *           TASK_KillCurrentTask
 590  *
 591  * Kill the currently running task. As it's not possible to kill the
 592  * current task like this, it is simply marked for destruction, and will
 593  * be killed when either TASK_Reschedule or this function is called again
 594  * in the context of another task.
 595  */
 596 void TASK_KillCurrentTask( int exitCode )
 597 {
 598     if (hTaskToKill && (hTaskToKill != hCurrentTask))
 599     {
 600         /* If another task is already marked for destruction, */
 601         /* we call kill it now, as we are in another context. */
 602         TASK_DeleteTask( hTaskToKill );
 603     }
 604
 605     if (nTaskCount <= 1)
 606     {
 607         dprintf_task( stddeb, "Killing the last task, exiting\n" );
 608         exit(0);
 609     }
 610
 611     /* Remove the task from the list to be sure we never switch back to it */
 612     TASK_UnlinkTask( hCurrentTask );
 613
 614     hTaskToKill = hCurrentTask;
 615     hLockedTask = 0;
 616
 617     Yield();
 618     /* We should never return from this Yield() */
 619
 620     fprintf(stderr,"It's alive! Alive!!!\n");
 621     exit(1);
 622 }
 623
 624
 625 /***********************************************************************
 626  *           TASK_Reschedule
 627  *
 628  * This is where all the magic of task-switching happens!
 629  *
 630  * This function should only be called via the TASK_SCHEDULE() macro, to make
 631  * sure that all the context is saved correctly.
 632  */
 633 void TASK_Reschedule(void)
 634 {
 635     TDB *pOldTask = NULL, *pNewTask;
 636     HTASK hTask = 0;
 637
 638 #ifdef CONFIG_IPC
 639     dde_reschedule();
 640 #endif
 641       /* First check if there's a task to kill */
 642
 643     if (hTaskToKill && (hTaskToKill != hCurrentTask))
 644     {
 645         TASK_DeleteTask( hTaskToKill );
 646         hTaskToKill = 0;
 647     }
 648
 649       /* If current task is locked, simply return */
 650
 651     if (hLockedTask) return;
 652
 653       /* Find a task to yield to */
 654
 655     pOldTask = (TDB *)GlobalLock( hCurrentTask );
 656     if (pOldTask && pOldTask->hYieldTo)
 657     {
 658         /* If a task is stored in hYieldTo of the current task (put there */
 659         /* by DirectedYield), yield to it only if it has events pending.  */
 660         hTask = pOldTask->hYieldTo;
 661         if (!(pNewTask = (TDB *)GlobalLock( hTask )) || !pNewTask->nEvents)
 662             hTask = 0;
 663     }
 664
 665     if (!hTask)
 666     {
 667         hTask = hFirstTask;
 668         while (hTask)
 669         {
 670             pNewTask = (TDB *)GlobalLock( hTask );
 671             if (pNewTask->nEvents && (hTask != hCurrentTask)) break;
 672             hTask = pNewTask->hNext;
 673         }
 674     }
 675
 676      /* If there's a task to kill, switch to any other task, */
 677      /* even if it doesn't have events pending. */
 678
 679     if (!hTask && hTaskToKill) hTask = hFirstTask;
 680
 681     if (!hTask) return;  /* Do nothing */
 682
 683     pNewTask = (TDB *)GlobalLock( hTask );
 684     dprintf_task( stddeb, "Switching to task "NPFMT" (%.8s)\n",
 685                   hTask, pNewTask->module_name );
 686
 687       /* Save the stacks of the previous task (if any) */
 688
 689 #ifndef WINELIB /* FIXME: JBP: IF1632 not allowed in libwine.a */
 690     if (pOldTask)
 691     {
 692         pOldTask->ss  = IF1632_Saved16_ss;
 693         pOldTask->sp  = IF1632_Saved16_sp;
 694         pOldTask->esp = IF1632_Saved32_esp;
 695     }
 696     else IF1632_Original32_esp = IF1632_Saved32_esp;
 697 #endif
 698
 699      /* Make the task the last in the linked list (round-robin scheduling) */
 700
 701     pNewTask->priority++;
 702     TASK_UnlinkTask( hTask );
 703     TASK_LinkTask( hTask );
 704     pNewTask->priority--;
 705
 706       /* Switch to the new stack */
 707
 708     hCurrentTask = hTask;
 709 #ifndef WINELIB /* FIXME: JBP: IF1632 not allowed in libwine.a */
 710     IF1632_Saved16_ss   = pNewTask->ss;
 711     IF1632_Saved16_sp   = pNewTask->sp;
 712     IF1632_Saved32_esp  = pNewTask->esp;
 713     IF1632_Stack32_base = WIN16_GlobalLock( pNewTask->hStack32 );
 714 #endif
 715 }
 716
 717
 718 /***********************************************************************
 719  *           InitTask  (KERNEL.91)
 720  */
 721 void InitTask( struct sigcontext_struct context )
 722 {
 723     static int firstTask = 1;
 724     TDB *pTask;
 725     NE_MODULE *pModule;
 726     SEGTABLEENTRY *pSegTable;
 727     INSTANCEDATA *pinstance;
 728     LONG stacklow, stackhi;
 729
 730     EAX_reg(&context) = 0;
 731     if (!(pTask = (TDB *)GlobalLock( hCurrentTask ))) return;
 732     if (!(pModule = (NE_MODULE *)GlobalLock( pTask->hModule ))) return;
 733
 734     if (firstTask)
 735     {
 736         extern BOOL WIDGETS_Init(void);
 737         extern BOOL WIN_CreateDesktopWindow(void);
 738
 739         /* Perform global initialisations that need a task context */
 740
 741           /* Initialize built-in window classes */
 742         if (!WIDGETS_Init()) return;
 743
 744           /* Create desktop window */
 745         if (!WIN_CreateDesktopWindow()) return;
 746
 747         firstTask = 0;
 748     }
 749
 750 #ifndef WINELIB
 751     NE_InitializeDLLs( pTask->hModule );
 752
 753     /* Registers on return are:
 754      * ax     1 if OK, 0 on error
 755      * cx     stack limit in bytes
 756      * dx     cmdShow parameter
 757      * si     instance handle of the previous instance
 758      * di     instance handle of the new task
 759      * es:bx  pointer to command-line inside PSP
 760      */
 761     EAX_reg(&context) = 1;
 762     EBX_reg(&context) = 0x81;
 763     ECX_reg(&context) = pModule->stack_size;
 764     EDX_reg(&context) = pTask->nCmdShow;
 765     ESI_reg(&context) = (DWORD)pTask->hPrevInstance;
 766     EDI_reg(&context) = (DWORD)pTask->hInstance;
 767     ES_reg (&context) = (WORD)pTask->hPDB;
 768 #endif
 769
 770     /* Initialize the local heap */
 771     if ( pModule->heap_size )
 772     {
 773         LocalInit( pTask->hInstance, 0, pModule->heap_size );
 774     }
 775
 776
 777     /* Initialize the INSTANCEDATA structure */
 778     pSegTable = NE_SEG_TABLE( pModule );
 779     stacklow = pSegTable[pModule->ss - 1].minsize;
 780     stackhi  = stacklow + pModule->stack_size;
 781     if (stackhi > 0xffff) stackhi = 0xffff;
 782     pinstance = (INSTANCEDATA *)PTR_SEG_OFF_TO_LIN(CURRENT_DS, 0);
 783     pinstance->stackbottom = stackhi; /* yup, that's right. Confused me too. */
 784     pinstance->stacktop    = stacklow;
 785 #ifndef WINELIB /* FIXME: JBP: IF1632 not allowed in libwine.a */
 786     pinstance->stackmin    = IF1632_Saved16_sp;
 787 #endif
 788 }
 789
 790
 791 /***********************************************************************
 792  *           WaitEvent  (KERNEL.30)
 793  */
 794 BOOL WaitEvent( HTASK hTask )
 795 {
 796     TDB *pTask;
 797
 798     if (!hTask) hTask = hCurrentTask;
 799     pTask = (TDB *)GlobalLock( hTask );
 800     if (pTask->nEvents > 0)
 801     {
 802         pTask->nEvents--;
 803         return FALSE;
 804     }
 805     TASK_SCHEDULE();
 806     /* When we get back here, we have an event (or the task is the only one) */
 807     if (pTask->nEvents > 0) pTask->nEvents--;
 808     return TRUE;
 809 }
 810
 811
 812 /***********************************************************************
 813  *           PostEvent  (KERNEL.31)
 814  */
 815 void PostEvent( HTASK hTask )
 816 {
 817     TDB *pTask;
 818
 819     if (!hTask) hTask = hCurrentTask;
 820     if (!(pTask = (TDB *)GlobalLock( hTask ))) return;
 821     pTask->nEvents++;
 822 }
 823
 824
 825 /***********************************************************************
 826  *           SetPriority  (KERNEL.32)
 827  */
 828 void SetPriority( HTASK hTask, int delta )
 829 {
 830     TDB *pTask;
 831     int newpriority;
 832
 833     if (!hTask) hTask = hCurrentTask;
 834     if (!(pTask = (TDB *)GlobalLock( hTask ))) return;
 835     newpriority = pTask->priority + delta;
 836     if (newpriority < -32) newpriority = -32;
 837     else if (newpriority > 15) newpriority = 15;
 838
 839     pTask->priority = newpriority + 1;
 840     TASK_UnlinkTask( hTask );
 841     TASK_LinkTask( hTask );
 842     pTask->priority--;
 843 }
 844
 845
 846 /***********************************************************************
 847  *           LockCurrentTask  (KERNEL.33)
 848  */
 849 HTASK LockCurrentTask( BOOL bLock )
 850 {
 851     if (bLock) hLockedTask = hCurrentTask;
 852     else hLockedTask = 0;
 853     return hLockedTask;
 854 }
 855
 856
 857 /***********************************************************************
 858  *           IsTaskLocked  (KERNEL.122)
 859  */
 860 WORD IsTaskLocked(void)
 861 {
 862     return hLockedTask;
 863 }
 864
 865
 866 /***********************************************************************
 867  *           OldYield  (KERNEL.117)
 868  */
 869 void OldYield(void)
 870 {
 871     TDB *pCurTask;
 872
 873     pCurTask = (TDB *)GlobalLock( hCurrentTask );
 874     if (pCurTask) pCurTask->nEvents++;  /* Make sure we get back here */
 875     TASK_SCHEDULE();
 876     if (pCurTask) pCurTask->nEvents--;
 877 }
 878
 879
 880 /***********************************************************************
 881  *           DirectedYield  (KERNEL.150)
 882  */
 883 void DirectedYield( HTASK hTask )
 884 {
 885     TDB *pCurTask;
 886
 887     if ((pCurTask = (TDB *)GlobalLock( hCurrentTask )) != NULL)
 888         pCurTask->hYieldTo = hTask;
 889
 890     OldYield();
 891 }
 892
 893
 894 /***********************************************************************
 895  *           Yield  (KERNEL.29)
 896  */
 897 void Yield(void)
 898 {
 899     DirectedYield( 0 );
 900 }
 901
 902
 903 /***********************************************************************
 904  *           MakeProcInstance  (KERNEL.51)
 905  */
 906 FARPROC MakeProcInstance( FARPROC func, HANDLE hInstance )
 907 {
 908     BYTE *thunk;
 909     SEGPTR thunkaddr;
 910
 911     thunkaddr = TASK_AllocThunk( hCurrentTask );
 912     if (!thunkaddr) return (FARPROC)0;
 913     thunk = PTR_SEG_TO_LIN( thunkaddr );
 914
 915     dprintf_task( stddeb, "MakeProcInstance("SPFMT","NPFMT"): got thunk "SPFMT"\n",
 916                   (SEGPTR)func, hInstance, (SEGPTR)thunkaddr );
 917
 918     *thunk++ = 0xb8;    /* movw instance, %ax */
 919 #ifndef WINELIB
 920     *thunk++ = (BYTE)(hInstance & 0xff);
 921     *thunk++ = (BYTE)(hInstance >> 8);
 922 #endif
 923     *thunk++ = 0xea;    /* ljmp func */
 924     *(DWORD *)thunk = (DWORD)func;
 925     return (FARPROC)thunkaddr;
 926 }
 927
 928
 929 /***********************************************************************
 930  *           FreeProcInstance  (KERNEL.52)
 931  */
 932 void FreeProcInstance( FARPROC func )
 933 {
 934     dprintf_task( stddeb, "FreeProcInstance("SPFMT")\n", (SEGPTR)func );
 935     TASK_FreeThunk( hCurrentTask, (SEGPTR)func );
 936 }
 937
 938
 939 /**********************************************************************
 940  *          GetCodeHandle    (KERNEL.93)
 941  */
 942 HANDLE GetCodeHandle( FARPROC proc )
 943 {
 944     HANDLE handle;
 945     BYTE *thunk = (BYTE *)PTR_SEG_TO_LIN( proc );
 946
 947     /* Return the code segment containing 'proc'. */
 948     /* Not sure if this is really correct (shouldn't matter that much). */
 949
 950     /* Check if it is really a thunk */
 951     if ((thunk[0] == 0xb8) && (thunk[3] == 0xea))
 952         handle = GlobalHandle( thunk[6] + (thunk[7] << 8) );
 953     else
 954         handle = GlobalHandle( HIWORD(proc) );
 955
 956     printf( "STUB: GetCodeHandle(%08lx) returning "NPFMT"\n",
 957             (DWORD)proc, handle );
 958     return handle;
 959 }
 960
 961
 962 /***********************************************************************
 963  *           SetTaskQueue  (KERNEL.34)
 964  */
 965 HGLOBAL SetTaskQueue( HANDLE hTask, HGLOBAL hQueue )
 966 {
 967     HGLOBAL hPrev;
 968     TDB *pTask;
 969
 970     if (!hTask) hTask = hCurrentTask;
 971     if (!(pTask = (TDB *)GlobalLock( hTask ))) return 0;
 972     hPrev = pTask->hQueue;
 973     pTask->hQueue = hQueue;
 974     return hPrev;
 975 }
 976
 977
 978 /***********************************************************************
 979  *           GetTaskQueue  (KERNEL.35)
 980  */
 981 HGLOBAL GetTaskQueue( HANDLE hTask )
 982 {
 983     TDB *pTask;
 984
 985     if (!hTask) hTask = hCurrentTask;
 986     if (!(pTask = (TDB *)GlobalLock( hTask ))) return 0;
 987     return pTask->hQueue;
 988 }
 989
 990
 991 /***********************************************************************
 992  *           GetTaskQueueDS  (KERNEL.118)
 993  */
 994 #ifndef WINELIB
 995 void GetTaskQueueDS( struct sigcontext_struct context )
 996 {
 997     DS_reg(&context) = GlobalHandleToSel( GetTaskQueue(0) );
 998 }
 999 #endif  /* WINELIB */
1000
1001
1002 /***********************************************************************
1003  *           GetTaskQueueES  (KERNEL.119)
1004  */
1005 #ifndef WINELIB
1006 void GetTaskQueueES( struct sigcontext_struct context )
1007 {
1008     ES_reg(&context) = GlobalHandleToSel( GetTaskQueue(0) );
1009 }
1010 #endif  /* WINELIB */
1011
1012
1013 /***********************************************************************
1014  *           GetCurrentTask   (KERNEL.36)
1015  */
1016 HTASK GetCurrentTask(void)
1017 {
1018       /* Undocumented: first task is returned in high word */
1019 #ifdef WINELIB32
1020     return hCurrentTask;
1021 #else
1022     return MAKELONG( hCurrentTask, hFirstTask );
1023 #endif
1024 }
1025
1026
1027 /***********************************************************************
1028  *           GetCurrentPDB   (KERNEL.37)
1029  */
1030 HANDLE GetCurrentPDB(void)
1031 {
1032     TDB *pTask;
1033
1034     if (!(pTask = (TDB *)GlobalLock( hCurrentTask ))) return 0;
1035     return pTask->hPDB;
1036 }
1037
1038
1039 /***********************************************************************
1040  *           GetInstanceData   (KERNEL.54)
1041  */
1042 int GetInstanceData( HANDLE instance, WORD buffer, int len )
1043 {
1044     char *ptr = (char *)GlobalLock( instance );
1045     if (!ptr || !len) return 0;
1046     if ((int)buffer + len >= 0x10000) len = 0x10000 - buffer;
1047     memcpy( ptr + buffer, (char *)GlobalLock( CURRENT_DS ) + buffer, len );
1048     return len;
1049 }
1050
1051
1052 /***********************************************************************
1053  *           GetDOSEnvironment   (KERNEL.131)
1054  */
1055 SEGPTR GetDOSEnvironment(void)
1056 {
1057     TDB *pTask;
1058
1059     if (!(pTask = (TDB *)GlobalLock( hCurrentTask ))) return 0;
1060     return (SEGPTR)WIN16_GlobalLock( pTask->pdb.environment );
1061 }
1062
1063
1064 /***********************************************************************
1065  *           GetNumTasks   (KERNEL.152)
1066  */
1067 WORD GetNumTasks(void)
1068 {
1069     return nTaskCount;
1070 }
1071
1072
1073 /***********************************************************************
1074  *           GetTaskDS   (KERNEL.155)
1075  */
1076 HINSTANCE GetTaskDS(void)
1077 {
1078     TDB *pTask;
1079
1080     if (!(pTask = (TDB *)GlobalLock( hCurrentTask ))) return 0;
1081     return pTask->hInstance;
1082 }
1083
1084
1085 /***********************************************************************
1086  *           IsTask   (KERNEL.320)
1087  */
1088 BOOL IsTask( HTASK hTask )
1089 {
1090     TDB *pTask;
1091
1092     if (!(pTask = (TDB *)GlobalLock( hTask ))) return FALSE;
1093     if (GlobalSize( hTask ) < sizeof(TDB)) return FALSE;
1094     return (pTask->magic == TDB_MAGIC);
1095 }
1096
1097
1098 /***********************************************************************
1099  *           GetExePtr   (KERNEL.133)
1100  */
1101 HMODULE GetExePtr( HANDLE handle )
1102 {
1103     char *ptr;
1104     HTASK hTask;
1105     HANDLE owner;
1106
1107       /* Check for module handle */
1108
1109     if (!(ptr = GlobalLock( handle ))) return 0;
1110     if (((NE_MODULE *)ptr)->magic == NE_SIGNATURE) return handle;
1111
1112       /* Check the owner for module handle */
1113
1114 #ifndef WINELIB
1115     owner = FarGetOwner( handle );
1116 #else
1117     owner = NULL;
1118     fprintf(stderr,"JBP: FarGetOwner() ignored.\n");
1119 #endif
1120     if (!(ptr = GlobalLock( owner ))) return 0;
1121     if (((NE_MODULE *)ptr)->magic == NE_SIGNATURE) return owner;
1122
1123       /* Search for this handle and its owner inside all tasks */
1124
1125     hTask = hFirstTask;
1126     while (hTask)
1127     {
1128         TDB *pTask = (TDB *)GlobalLock( hTask );
1129         if ((hTask == handle) ||
1130             (pTask->hInstance == handle) ||
1131             (pTask->hQueue == handle) ||
1132             (pTask->hPDB == handle)) return pTask->hModule;
1133         if ((hTask == owner) ||
1134             (pTask->hInstance == owner) ||
1135             (pTask->hQueue == owner) ||
1136             (pTask->hPDB == owner)) return pTask->hModule;
1137         hTask = pTask->hNext;
1138     }
1139     return 0;
1140 }
1141
1142
1143 /***********************************************************************
1144  *           TaskFirst   (TOOLHELP.63)
1145  */
1146 BOOL TaskFirst( TASKENTRY *lpte )
1147 {
1148     lpte->hNext = hFirstTask;
1149     return TaskNext( lpte );
1150 }
1151
1152
1153 /***********************************************************************
1154  *           TaskNext   (TOOLHELP.64)
1155  */
1156 BOOL TaskNext( TASKENTRY *lpte )
1157 {
1158     TDB *pTask;
1159     INSTANCEDATA *pInstData;
1160
1161     dprintf_toolhelp( stddeb, "TaskNext(%p): task="NPFMT"\n", lpte, lpte->hNext );
1162     if (!lpte->hNext) return FALSE;
1163     pTask = (TDB *)GlobalLock( lpte->hNext );
1164     if (!pTask || pTask->magic != TDB_MAGIC) return FALSE;
1165     pInstData = (INSTANCEDATA *)PTR_SEG_OFF_TO_LIN( pTask->hInstance, 0 );
1166     lpte->hTask         = lpte->hNext;
1167     lpte->hTaskParent   = pTask->hParent;
1168     lpte->hInst         = pTask->hInstance;
1169     lpte->hModule       = pTask->hModule;
1170     lpte->wSS           = pTask->ss;
1171     lpte->wSP           = pTask->sp;
1172     lpte->wStackTop     = pInstData->stacktop;
1173     lpte->wStackMinimum = pInstData->stackmin;
1174     lpte->wStackBottom  = pInstData->stackbottom;
1175     lpte->wcEvents      = pTask->nEvents;
1176     lpte->hQueue        = pTask->hQueue;
1177     strncpy( lpte->szModule, pTask->module_name, 8 );
1178     lpte->szModule[8]   = '\0';
1179     lpte->wPSPOffset    = 0x100;  /*??*/
1180     lpte->hNext         = pTask->hNext;
1181     return TRUE;
1182 }
1183
1184
1185 /***********************************************************************
1186  *           TaskFindHandle   (TOOLHELP.65)
1187  */
1188 BOOL TaskFindHandle( TASKENTRY *lpte, HTASK hTask )
1189 {
1190     lpte->hNext = hTask;
1191     return TaskNext( lpte );
1192 }