windows/queue.c

   1 /*
   2  * Message queues related functions
   3  *
   4  * Copyright 1993, 1994 Alexandre Julliard
   5  */
   6
   7 #include <string.h>
   8 #include <signal.h>
   9 #include <assert.h>
  10 #include "windef.h"
  11 #include "wingdi.h"
  12 #include "winerror.h"
  13 #include "wine/winbase16.h"
  14 #include "wine/winuser16.h"
  15 #include "queue.h"
  16 #include "win.h"
  17 #include "user.h"
  18 #include "hook.h"
  19 #include "thread.h"
  20 #include "debugtools.h"
  21 #include "server.h"
  22 #include "spy.h"
  23
  24 DEFAULT_DEBUG_CHANNEL(msg);
  25
  26
  27 static HQUEUE16 hExitingQueue = 0;
  28 static PERQUEUEDATA *pQDataWin16 = NULL;  /* Global perQData for Win16 tasks */
  29
  30 HQUEUE16 hActiveQueue = 0;
  31
  32
  33 /***********************************************************************
  34  *           PERQDATA_Addref
  35  *
  36  * Increment reference count for the PERQUEUEDATA instance
  37  * Returns reference count for debugging purposes
  38  */
  39 static void PERQDATA_Addref( PERQUEUEDATA *pQData )
  40 {
  41     assert(pQData != 0 );
  42     TRACE_(msg)("(): current refcount %lu ...\n", pQData->ulRefCount);
  43
  44     InterlockedIncrement( &pQData->ulRefCount );
  45 }
  46
  47
  48 /***********************************************************************
  49  *           PERQDATA_Release
  50  *
  51  * Release a reference to a PERQUEUEDATA instance.
  52  * Destroy the instance if no more references exist
  53  * Returns reference count for debugging purposes
  54  */
  55 static void PERQDATA_Release( PERQUEUEDATA *pQData )
  56 {
  57     assert(pQData != 0 );
  58     TRACE_(msg)("(): current refcount %lu ...\n",
  59           (LONG)pQData->ulRefCount );
  60
  61     if (!InterlockedDecrement( &pQData->ulRefCount ))
  62     {
  63         DeleteCriticalSection( &pQData->cSection );
  64
  65         TRACE_(msg)("(): deleting PERQUEUEDATA instance ...\n" );
  66
  67         /* Deleting our global 16 bit perQData? */
  68         if ( pQData == pQDataWin16 ) pQDataWin16 = 0;
  69
  70         /* Free the PERQUEUEDATA instance */
  71         HeapFree( GetProcessHeap(), 0, pQData );
  72     }
  73 }
  74
  75
  76 /***********************************************************************
  77  *           PERQDATA_CreateInstance
  78  *
  79  * Creates an instance of a reference counted PERQUEUEDATA element
  80  * for the message queue. perQData is stored globally for 16 bit tasks.
  81  *
  82  * Note: We don't implement perQdata exactly the same way Windows does.
  83  * Each perQData element is reference counted since it may be potentially
  84  * shared by multiple message Queues (via AttachThreadInput).
  85  * We only store the current values for Active, Capture and focus windows
  86  * currently.
  87  */
  88 static PERQUEUEDATA * PERQDATA_CreateInstance(void)
  89 {
  90     PERQUEUEDATA *pQData;
  91
  92     BOOL16 bIsWin16 = 0;
  93
  94     TRACE_(msg)("()\n");
  95
  96     /* Share a single instance of perQData for all 16 bit tasks */
  97     if ( ( bIsWin16 = !(NtCurrentTeb()->tibflags & TEBF_WIN32) ) )
  98     {
  99         /* If previously allocated, just bump up ref count */
 100         if ( pQDataWin16 )
 101         {
 102             PERQDATA_Addref( pQDataWin16 );
 103             return pQDataWin16;
 104         }
 105     }
 106
 107     /* Allocate PERQUEUEDATA from the system heap */
 108     if (!( pQData = (PERQUEUEDATA *) HeapAlloc( GetProcessHeap(), 0,
 109                                                     sizeof(PERQUEUEDATA) ) ))
 110         return 0;
 111
 112     /* Initialize */
 113     pQData->hWndCapture = pQData->hWndFocus = pQData->hWndActive = 0;
 114     pQData->ulRefCount = 1;
 115     pQData->nCaptureHT = HTCLIENT;
 116
 117     /* Note: We have an independent critical section for the per queue data
 118      * since this may be shared by different threads. see AttachThreadInput()
 119      */
 120     InitializeCriticalSection( &pQData->cSection );
 121     /* FIXME: not all per queue data critical sections should be global */
 122     MakeCriticalSectionGlobal( &pQData->cSection );
 123
 124     /* Save perQData globally for 16 bit tasks */
 125     if ( bIsWin16 )
 126         pQDataWin16 = pQData;
 127
 128     return pQData;
 129 }
 130
 131
 132 /***********************************************************************
 133  *           PERQDATA_GetFocusWnd
 134  *
 135  * Get the focus hwnd member in a threadsafe manner
 136  */
 137 HWND PERQDATA_GetFocusWnd( PERQUEUEDATA *pQData )
 138 {
 139     HWND hWndFocus;
 140     assert(pQData != 0 );
 141
 142     EnterCriticalSection( &pQData->cSection );
 143     hWndFocus = pQData->hWndFocus;
 144     LeaveCriticalSection( &pQData->cSection );
 145
 146     return hWndFocus;
 147 }
 148
 149
 150 /***********************************************************************
 151  *           PERQDATA_SetFocusWnd
 152  *
 153  * Set the focus hwnd member in a threadsafe manner
 154  */
 155 HWND PERQDATA_SetFocusWnd( PERQUEUEDATA *pQData, HWND hWndFocus )
 156 {
 157     HWND hWndFocusPrv;
 158     assert(pQData != 0 );
 159
 160     EnterCriticalSection( &pQData->cSection );
 161     hWndFocusPrv = pQData->hWndFocus;
 162     pQData->hWndFocus = hWndFocus;
 163     LeaveCriticalSection( &pQData->cSection );
 164
 165     return hWndFocusPrv;
 166 }
 167
 168
 169 /***********************************************************************
 170  *           PERQDATA_GetActiveWnd
 171  *
 172  * Get the active hwnd member in a threadsafe manner
 173  */
 174 HWND PERQDATA_GetActiveWnd( PERQUEUEDATA *pQData )
 175 {
 176     HWND hWndActive;
 177     assert(pQData != 0 );
 178
 179     EnterCriticalSection( &pQData->cSection );
 180     hWndActive = pQData->hWndActive;
 181     LeaveCriticalSection( &pQData->cSection );
 182
 183     return hWndActive;
 184 }
 185
 186
 187 /***********************************************************************
 188  *           PERQDATA_SetActiveWnd
 189  *
 190  * Set the active focus hwnd member in a threadsafe manner
 191  */
 192 HWND PERQDATA_SetActiveWnd( PERQUEUEDATA *pQData, HWND hWndActive )
 193 {
 194     HWND hWndActivePrv;
 195     assert(pQData != 0 );
 196
 197     EnterCriticalSection( &pQData->cSection );
 198     hWndActivePrv = pQData->hWndActive;
 199     pQData->hWndActive = hWndActive;
 200     LeaveCriticalSection( &pQData->cSection );
 201
 202     return hWndActivePrv;
 203 }
 204
 205
 206 /***********************************************************************
 207  *           PERQDATA_GetCaptureWnd
 208  *
 209  * Get the capture hwnd member in a threadsafe manner
 210  */
 211 HWND PERQDATA_GetCaptureWnd( INT *hittest )
 212 {
 213     MESSAGEQUEUE *queue;
 214     PERQUEUEDATA *pQData;
 215     HWND hWndCapture;
 216
 217     if (!(queue = QUEUE_Lock( GetFastQueue16() ))) return 0;
 218     pQData = queue->pQData;
 219
 220     EnterCriticalSection( &pQData->cSection );
 221     hWndCapture = pQData->hWndCapture;
 222     *hittest = pQData->nCaptureHT;
 223     LeaveCriticalSection( &pQData->cSection );
 224
 225     QUEUE_Unlock( queue );
 226     return hWndCapture;
 227 }
 228
 229
 230 /***********************************************************************
 231  *           PERQDATA_SetCaptureWnd
 232  *
 233  * Set the capture hwnd member in a threadsafe manner
 234  */
 235 HWND PERQDATA_SetCaptureWnd( HWND hWndCapture, INT hittest )
 236 {
 237     MESSAGEQUEUE *queue;
 238     PERQUEUEDATA *pQData;
 239     HWND hWndCapturePrv;
 240
 241     if (!(queue = QUEUE_Lock( GetFastQueue16() ))) return 0;
 242     pQData = queue->pQData;
 243
 244     EnterCriticalSection( &pQData->cSection );
 245     hWndCapturePrv = pQData->hWndCapture;
 246     pQData->hWndCapture = hWndCapture;
 247     pQData->nCaptureHT = hittest;
 248     LeaveCriticalSection( &pQData->cSection );
 249
 250     QUEUE_Unlock( queue );
 251     return hWndCapturePrv;
 252 }
 253
 254
 255
 256 /***********************************************************************
 257  *           QUEUE_Lock
 258  *
 259  * Function for getting a 32 bit pointer on queue structure. For thread
 260  * safeness programmers should use this function instead of GlobalLock to
 261  * retrieve a pointer on the structure. QUEUE_Unlock should also be called
 262  * when access to the queue structure is not required anymore.
 263  */
 264 MESSAGEQUEUE *QUEUE_Lock( HQUEUE16 hQueue )
 265 {
 266     MESSAGEQUEUE *queue;
 267
 268     HeapLock( GetProcessHeap() );  /* FIXME: a bit overkill */
 269     queue = GlobalLock16( hQueue );
 270     if ( !queue || (queue->magic != QUEUE_MAGIC) )
 271     {
 272         HeapUnlock( GetProcessHeap() );
 273         return NULL;
 274     }
 275
 276     queue->lockCount++;
 277     HeapUnlock( GetProcessHeap() );
 278     return queue;
 279 }
 280
 281
 282 /***********************************************************************
 283  *           QUEUE_Unlock
 284  *
 285  * Use with QUEUE_Lock to get a thread safe access to message queue
 286  * structure
 287  */
 288 void QUEUE_Unlock( MESSAGEQUEUE *queue )
 289 {
 290     if (queue)
 291     {
 292         HeapLock( GetProcessHeap() );  /* FIXME: a bit overkill */
 293
 294         if ( --queue->lockCount == 0 )
 295         {
 296             if (queue->server_queue)
 297                 CloseHandle( queue->server_queue );
 298             GlobalFree16( queue->self );
 299         }
 300
 301         HeapUnlock( GetProcessHeap() );
 302     }
 303 }
 304
 305
 306 /***********************************************************************
 307  *           QUEUE_IsExitingQueue
 308  */
 309 BOOL QUEUE_IsExitingQueue( HQUEUE16 hQueue )
 310 {
 311     return (hExitingQueue && (hQueue == hExitingQueue));
 312 }
 313
 314
 315 /***********************************************************************
 316  *           QUEUE_SetExitingQueue
 317  */
 318 void QUEUE_SetExitingQueue( HQUEUE16 hQueue )
 319 {
 320     hExitingQueue = hQueue;
 321 }
 322
 323
 324 /***********************************************************************
 325  *           QUEUE_CreateMsgQueue
 326  *
 327  * Creates a message queue. Doesn't link it into queue list!
 328  */
 329 static HQUEUE16 QUEUE_CreateMsgQueue( BOOL16 bCreatePerQData )
 330 {
 331     HQUEUE16 hQueue;
 332     HANDLE handle;
 333     MESSAGEQUEUE * msgQueue;
 334
 335     TRACE_(msg)("(): Creating message queue...\n");
 336
 337     if (!(hQueue = GlobalAlloc16( GMEM_FIXED | GMEM_ZEROINIT,
 338                                   sizeof(MESSAGEQUEUE) )))
 339         return 0;
 340
 341     msgQueue = (MESSAGEQUEUE *) GlobalLock16( hQueue );
 342     if ( !msgQueue )
 343         return 0;
 344
 345     if (bCreatePerQData)
 346     {
 347         SERVER_START_REQ( get_msg_queue )
 348         {
 349             SERVER_CALL_ERR();
 350             handle = req->handle;
 351         }
 352         SERVER_END_REQ;
 353         if (!handle)
 354         {
 355             ERR_(msg)("Cannot get thread queue");
 356             GlobalFree16( hQueue );
 357             return 0;
 358         }
 359         msgQueue->server_queue = handle;
 360     }
 361
 362     msgQueue->self = hQueue;
 363     msgQueue->lockCount = 1;
 364     msgQueue->magic = QUEUE_MAGIC;
 365
 366     /* Create and initialize our per queue data */
 367     msgQueue->pQData = bCreatePerQData ? PERQDATA_CreateInstance() : NULL;
 368
 369     return hQueue;
 370 }
 371
 372
 373 /***********************************************************************
 374  *           QUEUE_DeleteMsgQueue
 375  *
 376  * Unlinks and deletes a message queue.
 377  *
 378  * Note: We need to mask asynchronous events to make sure PostMessage works
 379  * even in the signal handler.
 380  */
 381 BOOL QUEUE_DeleteMsgQueue( HQUEUE16 hQueue )
 382 {
 383     MESSAGEQUEUE * msgQueue = QUEUE_Lock(hQueue);
 384
 385     TRACE_(msg)("(): Deleting message queue %04x\n", hQueue);
 386
 387     if (!hQueue || !msgQueue)
 388     {
 389         ERR_(msg)("invalid argument.\n");
 390         return 0;
 391     }
 392
 393     msgQueue->magic = 0;
 394
 395     if( hActiveQueue == hQueue ) hActiveQueue = 0;
 396     if (hExitingQueue == hQueue) hExitingQueue = 0;
 397
 398     HeapLock( GetProcessHeap() );  /* FIXME: a bit overkill */
 399
 400     /* Release per queue data if present */
 401     if ( msgQueue->pQData )
 402     {
 403         PERQDATA_Release( msgQueue->pQData );
 404         msgQueue->pQData = 0;
 405     }
 406
 407     msgQueue->self = 0;
 408
 409     HeapUnlock( GetProcessHeap() );
 410
 411     /* free up resource used by MESSAGEQUEUE structure */
 412     msgQueue->lockCount--;
 413     QUEUE_Unlock( msgQueue );
 414
 415     return 1;
 416 }
 417
 418
 419 /***********************************************************************
 420  *           QUEUE_CleanupWindow
 421  *
 422  * Cleanup the queue to account for a window being deleted.
 423  */
 424 void QUEUE_CleanupWindow( HWND hwnd )
 425 {
 426     SERVER_START_REQ( cleanup_window_queue )
 427     {
 428         req->win = hwnd;
 429         SERVER_CALL();
 430     }
 431     SERVER_END_REQ;
 432 }
 433
 434
 435 /***********************************************************************
 436  *           QUEUE_GetQueueTask
 437  */
 438 HTASK16 QUEUE_GetQueueTask( HQUEUE16 hQueue )
 439 {
 440     HTASK16 hTask = 0;
 441
 442     MESSAGEQUEUE *queue = QUEUE_Lock( hQueue );
 443
 444     if (queue)
 445     {
 446         hTask = queue->teb->htask16;
 447         QUEUE_Unlock( queue );
 448     }
 449
 450     return hTask;
 451 }
 452
 453
 454 /***********************************************************************
 455  *              PostQuitMessage (USER.6)
 456  */
 457 void WINAPI PostQuitMessage16( INT16 exitCode )
 458 {
 459     PostQuitMessage( exitCode );
 460 }
 461
 462
 463 /***********************************************************************
 464  *              PostQuitMessage (USER32.@)
 465  *
 466  * PostQuitMessage() posts a message to the system requesting an
 467  * application to terminate execution. As a result of this function,
 468  * the WM_QUIT message is posted to the application, and
 469  * PostQuitMessage() returns immediately.  The exitCode parameter
 470  * specifies an application-defined exit code, which appears in the
 471  * _wParam_ parameter of the WM_QUIT message posted to the application.
 472  *
 473  * CONFORMANCE
 474  *
 475  *  ECMA-234, Win32
 476  */
 477 void WINAPI PostQuitMessage( INT exitCode )
 478 {
 479     PostThreadMessageW( GetCurrentThreadId(), WM_QUIT, exitCode, 0 );
 480 }
 481
 482
 483 /***********************************************************************
 484  *              GetWindowTask (USER.224)
 485  */
 486 HTASK16 WINAPI GetWindowTask16( HWND16 hwnd )
 487 {
 488     HTASK16 retvalue;
 489     WND *wndPtr = WIN_FindWndPtr( hwnd );
 490
 491     if (!wndPtr) return 0;
 492     retvalue = QUEUE_GetQueueTask( wndPtr->hmemTaskQ );
 493     WIN_ReleaseWndPtr(wndPtr);
 494     return retvalue;
 495 }
 496
 497 /***********************************************************************
 498  *              GetWindowThreadProcessId (USER32.@)
 499  */
 500 DWORD WINAPI GetWindowThreadProcessId( HWND hwnd, LPDWORD process )
 501 {
 502     DWORD retvalue;
 503     MESSAGEQUEUE *queue;
 504
 505     WND *wndPtr = WIN_FindWndPtr( hwnd );
 506     if (!wndPtr) return 0;
 507
 508     queue = QUEUE_Lock( wndPtr->hmemTaskQ );
 509     WIN_ReleaseWndPtr(wndPtr);
 510
 511     if (!queue) return 0;
 512
 513     if ( process ) *process = (DWORD)queue->teb->pid;
 514     retvalue = (DWORD)queue->teb->tid;
 515
 516     QUEUE_Unlock( queue );
 517     return retvalue;
 518 }
 519
 520
 521 /***********************************************************************
 522  *              SetMessageQueue (USER.266)
 523  */
 524 BOOL16 WINAPI SetMessageQueue16( INT16 size )
 525 {
 526     return SetMessageQueue( size );
 527 }
 528
 529
 530 /***********************************************************************
 531  *              SetMessageQueue (USER32.@)
 532  */
 533 BOOL WINAPI SetMessageQueue( INT size )
 534 {
 535     /* now obsolete the message queue will be expanded dynamically
 536      as necessary */
 537
 538     /* access the queue to create it if it's not existing */
 539     GetFastQueue16();
 540
 541     return TRUE;
 542 }
 543
 544 /***********************************************************************
 545  *              InitThreadInput (USER.409)
 546  */
 547 HQUEUE16 WINAPI InitThreadInput16( WORD unknown, WORD flags )
 548 {
 549     HQUEUE16 hQueue;
 550     MESSAGEQUEUE *queuePtr;
 551
 552     TEB *teb = NtCurrentTeb();
 553
 554     if (!teb)
 555         return 0;
 556
 557     hQueue = teb->queue;
 558
 559     if ( !hQueue )
 560     {
 561         /* Create thread message queue */
 562         if( !(hQueue = QUEUE_CreateMsgQueue( TRUE )))
 563         {
 564             ERR_(msg)("failed!\n");
 565             return FALSE;
 566         }
 567
 568         /* Link new queue into list */
 569         queuePtr = QUEUE_Lock( hQueue );
 570         queuePtr->teb = NtCurrentTeb();
 571
 572         HeapLock( GetProcessHeap() );  /* FIXME: a bit overkill */
 573         SetThreadQueue16( 0, hQueue );
 574         teb->queue = hQueue;
 575         HeapUnlock( GetProcessHeap() );
 576
 577         QUEUE_Unlock( queuePtr );
 578     }
 579
 580     return hQueue;
 581 }
 582
 583 /***********************************************************************
 584  *              GetQueueStatus (USER.334)
 585  */
 586 DWORD WINAPI GetQueueStatus16( UINT16 flags )
 587 {
 588     return GetQueueStatus( flags );
 589 }
 590
 591 /***********************************************************************
 592  *              GetQueueStatus (USER32.@)
 593  */
 594 DWORD WINAPI GetQueueStatus( UINT flags )
 595 {
 596     DWORD ret = 0;
 597
 598     SERVER_START_REQ( get_queue_status )
 599     {
 600         req->clear = 1;
 601         SERVER_CALL();
 602         ret = MAKELONG( req->changed_bits & flags, req->wake_bits & flags );
 603     }
 604     SERVER_END_REQ;
 605     return ret;
 606 }
 607
 608
 609 /***********************************************************************
 610  *              GetInputState (USER.335)
 611  */
 612 BOOL16 WINAPI GetInputState16(void)
 613 {
 614     return GetInputState();
 615 }
 616
 617 /***********************************************************************
 618  *              GetInputState   (USER32.@)
 619  */
 620 BOOL WINAPI GetInputState(void)
 621 {
 622     DWORD ret = 0;
 623
 624     SERVER_START_REQ( get_queue_status )
 625     {
 626         req->clear = 0;
 627         SERVER_CALL();
 628         ret = req->wake_bits & (QS_KEY | QS_MOUSEBUTTON);
 629     }
 630     SERVER_END_REQ;
 631     return ret;
 632 }
 633
 634 /***********************************************************************
 635  *              GetMessagePos (USER.119)
 636  *              GetMessagePos (USER32.@)
 637  *
 638  * The GetMessagePos() function returns a long value representing a
 639  * cursor position, in screen coordinates, when the last message
 640  * retrieved by the GetMessage() function occurs. The x-coordinate is
 641  * in the low-order word of the return value, the y-coordinate is in
 642  * the high-order word. The application can use the MAKEPOINT()
 643  * macro to obtain a POINT structure from the return value.
 644  *
 645  * For the current cursor position, use GetCursorPos().
 646  *
 647  * RETURNS
 648  *
 649  * Cursor position of last message on success, zero on failure.
 650  *
 651  * CONFORMANCE
 652  *
 653  * ECMA-234, Win32
 654  *
 655  */
 656 DWORD WINAPI GetMessagePos(void)
 657 {
 658     MESSAGEQUEUE *queue;
 659     DWORD ret;
 660
 661     if (!(queue = QUEUE_Lock( GetFastQueue16() ))) return 0;
 662     ret = queue->GetMessagePosVal;
 663     QUEUE_Unlock( queue );
 664
 665     return ret;
 666 }
 667
 668
 669 /***********************************************************************
 670  *              GetMessageTime (USER.120)
 671  *              GetMessageTime (USER32.@)
 672  *
 673  * GetMessageTime() returns the message time for the last message
 674  * retrieved by the function. The time is measured in milliseconds with
 675  * the same offset as GetTickCount().
 676  *
 677  * Since the tick count wraps, this is only useful for moderately short
 678  * relative time comparisons.
 679  *
 680  * RETURNS
 681  *
 682  * Time of last message on success, zero on failure.
 683  *
 684  * CONFORMANCE
 685  *
 686  * ECMA-234, Win32
 687  *
 688  */
 689 LONG WINAPI GetMessageTime(void)
 690 {
 691     MESSAGEQUEUE *queue;
 692     LONG ret;
 693
 694     if (!(queue = QUEUE_Lock( GetFastQueue16() ))) return 0;
 695     ret = queue->GetMessageTimeVal;
 696     QUEUE_Unlock( queue );
 697
 698     return ret;
 699 }
 700
 701
 702 /***********************************************************************
 703  *              GetMessageExtraInfo (USER.288)
 704  *              GetMessageExtraInfo (USER32.@)
 705  */
 706 LONG WINAPI GetMessageExtraInfo(void)
 707 {
 708     MESSAGEQUEUE *queue;
 709     LONG ret;
 710
 711     if (!(queue = QUEUE_Lock( GetFastQueue16() ))) return 0;
 712     ret = queue->GetMessageExtraInfoVal;
 713     QUEUE_Unlock( queue );
 714
 715     return ret;
 716 }
 717
 718
 719 /**********************************************************************
 720  *              AttachThreadInput (USER32.@) Attaches input of 1 thread to other
 721  *
 722  * Attaches the input processing mechanism of one thread to that of
 723  * another thread.
 724  *
 725  * RETURNS
 726  *    Success: TRUE
 727  *    Failure: FALSE
 728  *
 729  * TODO:
 730  *    1. Reset the Key State (currenly per thread key state is not maintained)
 731  */
 732 BOOL WINAPI AttachThreadInput(
 733     DWORD idAttach,   /* [in] Thread to attach */
 734     DWORD idAttachTo, /* [in] Thread to attach to */
 735     BOOL fAttach)   /* [in] Attach or detach */
 736 {
 737     MESSAGEQUEUE *pSrcMsgQ = 0, *pTgtMsgQ = 0;
 738     BOOL16 bRet = 0;
 739
 740     SetLastError(ERROR_CALL_NOT_IMPLEMENTED);
 741
 742     /* A thread cannot attach to itself */
 743     if ( idAttach == idAttachTo )
 744         goto CLEANUP;
 745
 746     /* According to the docs this method should fail if a
 747      * "Journal record" hook is installed. (attaches all input queues together)
 748      */
 749     if ( HOOK_IsHooked( WH_JOURNALRECORD ) )
 750         goto CLEANUP;
 751
 752     /* Retrieve message queues corresponding to the thread id's */
 753     pTgtMsgQ = QUEUE_Lock( GetThreadQueue16( idAttach ) );
 754     pSrcMsgQ = QUEUE_Lock( GetThreadQueue16( idAttachTo ) );
 755
 756     /* Ensure we have message queues and that Src and Tgt threads
 757      * are not system threads.
 758      */
 759     if ( !pSrcMsgQ || !pTgtMsgQ || !pSrcMsgQ->pQData || !pTgtMsgQ->pQData )
 760         goto CLEANUP;
 761
 762     if (fAttach)   /* Attach threads */
 763     {
 764         /* Only attach if currently detached  */
 765         if ( pTgtMsgQ->pQData != pSrcMsgQ->pQData )
 766         {
 767             /* First release the target threads perQData */
 768             PERQDATA_Release( pTgtMsgQ->pQData );
 769
 770             /* Share a reference to the source threads perQDATA */
 771             PERQDATA_Addref( pSrcMsgQ->pQData );
 772             pTgtMsgQ->pQData = pSrcMsgQ->pQData;
 773         }
 774     }
 775     else    /* Detach threads */
 776     {
 777         /* Only detach if currently attached */
 778         if ( pTgtMsgQ->pQData == pSrcMsgQ->pQData )
 779         {
 780             /* First release the target threads perQData */
 781             PERQDATA_Release( pTgtMsgQ->pQData );
 782
 783             /* Give the target thread its own private perQDATA once more */
 784             pTgtMsgQ->pQData = PERQDATA_CreateInstance();
 785         }
 786     }
 787
 788     /* TODO: Reset the Key State */
 789
 790     bRet = 1;      /* Success */
 791
 792 CLEANUP:
 793
 794     /* Unlock the queues before returning */
 795     if ( pSrcMsgQ )
 796         QUEUE_Unlock( pSrcMsgQ );
 797     if ( pTgtMsgQ )
 798         QUEUE_Unlock( pTgtMsgQ );
 799
 800     return bRet;
 801 }