git.oblomov.eu Git - wine/blob - dlls/ole32/stg_bigblockfile.c

   1 /******************************************************************************
   2  *
   3  * BigBlockFile
   4  *
   5  * This is the implementation of a file that consists of blocks of
   6  * a predetermined size.
   7  * This class is used in the Compound File implementation of the
   8  * IStorage and IStream interfaces. It provides the functionality
   9  * to read and write any blocks in the file as well as setting and
  10  * obtaining the size of the file.
  11  * The blocks are indexed sequentially from the start of the file
  12  * starting with -1.
  13  *
  14  * TODO:
  15  * - Support for a transacted mode
  16  *
  17  * Copyright 1999 Thuy Nguyen
  18  *
  19  */
  20
  21 #include <assert.h>
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25
  26 #include "winbase.h"
  27 #include "winerror.h"
  28 #include "wine/obj_storage.h"
  29 #include "ole2.h"
  30
  31 #include "storage32.h"
  32
  33 #include "debugtools.h"
  34
  35 DEFAULT_DEBUG_CHANNEL(storage)
  36
  37 /***********************************************************
  38  * Data structures used internally by the BigBlockFile
  39  * class.
  40  */
  41
  42 /***
  43  * Itdentifies a single big block and the related
  44  * information
  45  */
  46 struct BigBlock
  47 {
  48   BigBlock * next;
  49   DWORD index;
  50   DWORD access_mode;
  51   LPVOID lpBlock;
  52 };
  53
  54 /***
  55  * This structure identifies the paged that are mapped
  56  * from the file and their position in memory. It is
  57  * also used to hold a reference count to those pages.
  58  */
  59 struct MappedPage
  60 {
  61   MappedPage * next;
  62   DWORD number;
  63   int ref;
  64   LPVOID lpBytes;
  65 };
  66
  67 #define PAGE_SIZE       131072
  68 #define BLOCKS_PER_PAGE 256
  69
  70 #define NUMBER_OF_MAPPED_PAGES 100
  71
  72 /***********************************************************
  73  * Prototypes for private methods
  74  */
  75 static void*     BIGBLOCKFILE_GetMappedView(LPBIGBLOCKFILE This,
  76                                             DWORD          pagenum,
  77                                             DWORD          desired_access);
  78 static void      BIGBLOCKFILE_ReleaseMappedPage(LPBIGBLOCKFILE This,
  79                                                 DWORD          pagenum,
  80                                                 DWORD          access);
  81 static void      BIGBLOCKFILE_FreeAllMappedPages(LPBIGBLOCKFILE This);
  82 static void*     BIGBLOCKFILE_GetBigBlockPointer(LPBIGBLOCKFILE This,
  83                                                  ULONG          index,
  84                                                  DWORD          desired_access);
  85 static BigBlock* BIGBLOCKFILE_GetBigBlockFromPointer(LPBIGBLOCKFILE This,
  86                                                      void*          pBlock);
  87 static void      BIGBLOCKFILE_RemoveBlock(LPBIGBLOCKFILE This,
  88                                           ULONG          index);
  89 static BigBlock* BIGBLOCKFILE_AddBigBlock(LPBIGBLOCKFILE This,
  90                                           ULONG          index);
  91 static BigBlock* BIGBLOCKFILE_CreateBlock(ULONG index);
  92 static DWORD     BIGBLOCKFILE_GetProtectMode(DWORD openFlags);
  93 static BOOL      BIGBLOCKFILE_FileInit(LPBIGBLOCKFILE This, HANDLE hFile);
  94 static BOOL      BIGBLOCKFILE_MemInit(LPBIGBLOCKFILE This, ILockBytes* plkbyt);
  95 static void      BIGBLOCKFILE_RemoveAllBlocks(LPBIGBLOCKFILE This);
  96
  97 /******************************************************************************
  98  *      BIGBLOCKFILE_Construct
  99  *
 100  * Construct a big block file. Create the file mapping object.
 101  * Create the read only mapped pages list, the writeable mapped page list
 102  * and the blocks in use list.
 103  */
 104 BigBlockFile * BIGBLOCKFILE_Construct(
 105   HANDLE   hFile,
 106   ILockBytes* pLkByt,
 107   DWORD    openFlags,
 108   ULONG    blocksize,
 109   BOOL     fileBased)
 110 {
 111   LPBIGBLOCKFILE This;
 112
 113   This = (LPBIGBLOCKFILE)HeapAlloc(GetProcessHeap(), 0, sizeof(BigBlockFile));
 114
 115   if (This == NULL)
 116     return NULL;
 117
 118   This->fileBased = fileBased;
 119
 120   This->flProtect = BIGBLOCKFILE_GetProtectMode(openFlags);
 121
 122   This->blocksize = blocksize;
 123
 124   /* initialize the block list
 125    */
 126   This->headblock = NULL;
 127
 128   if (This->fileBased)
 129   {
 130     if (!BIGBLOCKFILE_FileInit(This, hFile))
 131     {
 132       HeapFree(GetProcessHeap(), 0, This);
 133       return NULL;
 134     }
 135   }
 136   else
 137   {
 138     if (!BIGBLOCKFILE_MemInit(This, pLkByt))
 139     {
 140       HeapFree(GetProcessHeap(), 0, This);
 141       return NULL;
 142     }
 143   }
 144
 145   return This;
 146 }
 147
 148 /******************************************************************************
 149  *      BIGBLOCKFILE_FileInit
 150  *
 151  * Initialize a big block object supported by a file.
 152  */
 153 static BOOL BIGBLOCKFILE_FileInit(LPBIGBLOCKFILE This, HANDLE hFile)
 154 {
 155   This->pLkbyt     = NULL;
 156   This->hbytearray = 0;
 157   This->pbytearray = NULL;
 158
 159   This->hfile = hFile;
 160
 161   if (This->hfile == INVALID_HANDLE_VALUE)
 162     return FALSE;
 163
 164   /* create the file mapping object
 165    */
 166   This->hfilemap = CreateFileMappingA(This->hfile,
 167                                       NULL,
 168                                       This->flProtect,
 169                                       0, 0,
 170                                       NULL);
 171
 172   if (This->hfilemap == NULL)
 173   {
 174     CloseHandle(This->hfile);
 175     return FALSE;
 176   }
 177
 178   This->filesize.s.LowPart = GetFileSize(This->hfile, NULL);
 179
 180   /* create the mapped pages list
 181    */
 182   This->maplisthead = HeapAlloc(GetProcessHeap(), 0, sizeof(MappedPage));
 183
 184   if (This->maplisthead == NULL)
 185   {
 186     CloseHandle(This->hfilemap);
 187     CloseHandle(This->hfile);
 188     return FALSE;
 189   }
 190
 191   This->maplisthead->next = NULL;
 192
 193   return TRUE;
 194 }
 195
 196 /******************************************************************************
 197  *      BIGBLOCKFILE_MemInit
 198  *
 199  * Initialize a big block object supported by an ILockBytes on HGLOABL.
 200  */
 201 static BOOL BIGBLOCKFILE_MemInit(LPBIGBLOCKFILE This, ILockBytes* plkbyt)
 202 {
 203   This->hfile       = 0;
 204   This->hfilemap    = NULL;
 205   This->maplisthead = NULL;
 206
 207   /*
 208    * Retrieve the handle to the byte array from the LockByte object.
 209    */
 210   if (GetHGlobalFromILockBytes(plkbyt, &(This->hbytearray)) != S_OK)
 211   {
 212     FIXME("May not be an ILockBytes on HGLOBAL\n");
 213     return FALSE;
 214   }
 215
 216   This->pLkbyt = plkbyt;
 217
 218   /*
 219    * Increment the reference count of the ILockByte object since
 220    * we're keeping a reference to it.
 221    */
 222   ILockBytes_AddRef(This->pLkbyt);
 223
 224   This->filesize.s.LowPart = GlobalSize(This->hbytearray);
 225   This->filesize.s.HighPart = 0;
 226
 227   This->pbytearray = GlobalLock(This->hbytearray);
 228
 229   return TRUE;
 230 }
 231
 232 /******************************************************************************
 233  *      BIGBLOCKFILE_Destructor
 234  *
 235  * Destructor. Clean up, free memory.
 236  */
 237 void BIGBLOCKFILE_Destructor(
 238   LPBIGBLOCKFILE This)
 239 {
 240   if (This->fileBased)
 241   {
 242     /* unmap all views and destroy the mapped page list
 243      */
 244     BIGBLOCKFILE_FreeAllMappedPages(This);
 245     HeapFree(GetProcessHeap(), 0, This->maplisthead);
 246
 247     /* close all open handles
 248      */
 249     CloseHandle(This->hfilemap);
 250     CloseHandle(This->hfile);
 251   }
 252   else
 253   {
 254     GlobalUnlock(This->hbytearray);
 255     ILockBytes_Release(This->pLkbyt);
 256   }
 257
 258   /*
 259    * Destroy the blocks list.
 260    */
 261   BIGBLOCKFILE_RemoveAllBlocks(This);
 262
 263   /* destroy this
 264    */
 265   HeapFree(GetProcessHeap(), 0, This);
 266 }
 267
 268 /******************************************************************************
 269  *      BIGBLOCKFILE_GetROBigBlock
 270  *
 271  * Returns the specified block in read only mode.
 272  * Will return NULL if the block doesn't exists.
 273  */
 274 void* BIGBLOCKFILE_GetROBigBlock(
 275   LPBIGBLOCKFILE This,
 276   ULONG          index)
 277 {
 278   /*
 279    * block index starts at -1
 280    * translate to zero based index
 281    */
 282   if (index == 0xffffffff)
 283     index = 0;
 284   else
 285     index++;
 286
 287   /*
 288    * validate the block index
 289    *
 290    */
 291   if ((This->blocksize * (index + 1)) >
 292       (This->filesize.s.LowPart +
 293        (This->blocksize - (This->filesize.s.LowPart % This->blocksize))))
 294     return 0;
 295
 296   return BIGBLOCKFILE_GetBigBlockPointer(This, index, FILE_MAP_READ);
 297 }
 298
 299 /******************************************************************************
 300  *      BIGBLOCKFILE_GetBigBlock
 301  *
 302  * Returns the specified block.
 303  * Will grow the file if necessary.
 304  */
 305 void* BIGBLOCKFILE_GetBigBlock(LPBIGBLOCKFILE This, ULONG index)
 306 {
 307   /*
 308    * block index starts at -1
 309    * translate to zero based index
 310    */
 311   if (index == 0xffffffff)
 312     index = 0;
 313   else
 314     index++;
 315
 316   /*
 317    * make sure that the block physically exists
 318    */
 319   if ((This->blocksize * (index + 1)) > This->filesize.s.LowPart)
 320   {
 321     ULARGE_INTEGER newSize;
 322
 323     newSize.s.HighPart = 0;
 324     newSize.s.LowPart = This->blocksize * (index + 1);
 325
 326     BIGBLOCKFILE_SetSize(This, newSize);
 327   }
 328
 329   return BIGBLOCKFILE_GetBigBlockPointer(This, index, FILE_MAP_WRITE);
 330 }
 331
 332 /******************************************************************************
 333  *      BIGBLOCKFILE_ReleaseBigBlock
 334  *
 335  * Releases the specified block.
 336  */
 337 void BIGBLOCKFILE_ReleaseBigBlock(LPBIGBLOCKFILE This, void *pBlock)
 338 {
 339   DWORD page_num;
 340   BigBlock* theBigBlock;
 341
 342   if (pBlock == NULL)
 343     return;
 344
 345   /*
 346    * get the block from the block list
 347    */
 348   theBigBlock = BIGBLOCKFILE_GetBigBlockFromPointer(This, pBlock);
 349
 350   if (theBigBlock == NULL)
 351     return;
 352
 353   if (This->fileBased)
 354   {
 355     /*
 356      * find out which page this block is in
 357      */
 358     page_num = theBigBlock->index / BLOCKS_PER_PAGE;
 359
 360     /*
 361      * release this page
 362      */
 363     BIGBLOCKFILE_ReleaseMappedPage(This, page_num, theBigBlock->access_mode);
 364   }
 365
 366   /*
 367    * remove block from list
 368    */
 369   BIGBLOCKFILE_RemoveBlock(This, theBigBlock->index);
 370 }
 371
 372 /******************************************************************************
 373  *      BIGBLOCKFILE_SetSize
 374  *
 375  * Sets the size of the file.
 376  *
 377  */
 378 void BIGBLOCKFILE_SetSize(LPBIGBLOCKFILE This, ULARGE_INTEGER newSize)
 379 {
 380   if (This->filesize.s.LowPart == newSize.s.LowPart)
 381     return;
 382
 383   if (This->fileBased)
 384   {
 385     /*
 386      * unmap all views, must be done before call to SetEndFile
 387      */
 388     BIGBLOCKFILE_FreeAllMappedPages(This);
 389
 390     /*
 391      * close file-mapping object, must be done before call to SetEndFile
 392      */
 393     CloseHandle(This->hfilemap);
 394     This->hfilemap = NULL;
 395
 396     /*
 397      * set the new end of file
 398      */
 399     SetFilePointer(This->hfile, newSize.s.LowPart, NULL, FILE_BEGIN);
 400     SetEndOfFile(This->hfile);
 401
 402     /*
 403      * re-create the file mapping object
 404      */
 405     This->hfilemap = CreateFileMappingA(This->hfile,
 406                                         NULL,
 407                                         This->flProtect,
 408                                         0, 0,
 409                                         NULL);
 410   }
 411   else
 412   {
 413     GlobalUnlock(This->hbytearray);
 414
 415     /*
 416      * Resize the byte array object.
 417      */
 418     ILockBytes_SetSize(This->pLkbyt, newSize);
 419
 420     /*
 421      * Re-acquire the handle, it may have changed.
 422      */
 423     GetHGlobalFromILockBytes(This->pLkbyt, &This->hbytearray);
 424     This->pbytearray = GlobalLock(This->hbytearray);
 425   }
 426
 427   /*
 428    * empty the blocks list.
 429    */
 430   BIGBLOCKFILE_RemoveAllBlocks(This);
 431
 432   This->filesize.s.LowPart = newSize.s.LowPart;
 433   This->filesize.s.HighPart = newSize.s.HighPart;
 434 }
 435
 436 /******************************************************************************
 437  *      BIGBLOCKFILE_GetSize
 438  *
 439  * Returns the size of the file.
 440  *
 441  */
 442 ULARGE_INTEGER BIGBLOCKFILE_GetSize(LPBIGBLOCKFILE This)
 443 {
 444   return This->filesize;
 445 }
 446
 447 /******************************************************************************
 448  *      BIGBLOCKFILE_GetBigBlockPointer     [PRIVATE]
 449  *
 450  * Returns a pointer to the specified block.
 451  */
 452 static void* BIGBLOCKFILE_GetBigBlockPointer(
 453   LPBIGBLOCKFILE This,
 454   ULONG          index,
 455   DWORD          desired_access)
 456 {
 457   DWORD block_num;
 458   void * pBytes;
 459   BigBlock *aBigBlock;
 460
 461   /* get the big block from the list or add it to the list
 462    */
 463   aBigBlock = BIGBLOCKFILE_AddBigBlock(This, index);
 464
 465   if (aBigBlock == NULL)
 466     return NULL;
 467
 468   /* we already have an address for this block
 469    */
 470   if (aBigBlock->lpBlock != NULL)
 471   {
 472     /* make sure the desired access matches what we already have
 473      */
 474     if (aBigBlock->access_mode == desired_access)
 475       return aBigBlock->lpBlock;
 476     else
 477       return NULL;
 478   }
 479
 480   /*
 481    * else aBigBlock->lpBigBlock == NULL, it's a new block
 482    */
 483
 484   if (This->fileBased)
 485   {
 486     DWORD page_num;
 487
 488     /* find out which page this block is in
 489      */
 490     page_num = index / BLOCKS_PER_PAGE;
 491
 492     /* offset of the block in the page
 493      */
 494     block_num = index % BLOCKS_PER_PAGE;
 495
 496     /* get a pointer to the first byte in the page
 497      */
 498     pBytes = BIGBLOCKFILE_GetMappedView(This, page_num, desired_access);
 499   }
 500   else
 501   {
 502     pBytes = This->pbytearray;
 503     block_num = index;
 504   }
 505
 506   if (pBytes == NULL)
 507     return NULL;
 508
 509   /* initialize block
 510    */
 511   aBigBlock->lpBlock = ((BYTE*)pBytes + (block_num*This->blocksize));
 512   aBigBlock->access_mode = desired_access;
 513
 514   return aBigBlock->lpBlock;
 515 }
 516
 517 /******************************************************************************
 518  *      BIGBLOCKFILE_CreateBlock      [PRIVATE]
 519  *
 520  * Creates a node of the blocks list.
 521  */
 522 static BigBlock* BIGBLOCKFILE_CreateBlock(
 523   ULONG index)
 524 {
 525   BigBlock *newBigBlock;
 526
 527   /* create new list node
 528    */
 529   newBigBlock = HeapAlloc(GetProcessHeap(), 0, sizeof(BigBlock));
 530
 531   if (newBigBlock == NULL)
 532     return NULL;
 533
 534   /* initialize node
 535    */
 536   newBigBlock->index = index;
 537   newBigBlock->lpBlock = NULL;
 538
 539   return newBigBlock;
 540 }
 541
 542 /******************************************************************************
 543  *      BIGBLOCKFILE_AddBigBlock      [PRIVATE]
 544  *
 545  * Returns the specified block from the blocks list.
 546  * If the block is not found in the list, we will create it and add it to the
 547  * list.
 548  */
 549 static BigBlock* BIGBLOCKFILE_AddBigBlock(
 550   LPBIGBLOCKFILE This,
 551   ULONG          index)
 552 {
 553   BigBlock *current = This->headblock;
 554   BigBlock *newBigBlock;
 555
 556   if (current == NULL) /* empty list */
 557   {
 558     newBigBlock = BIGBLOCKFILE_CreateBlock(index);
 559
 560     if (newBigBlock != NULL)
 561     {
 562       newBigBlock->next = NULL;
 563       This->headblock = newBigBlock;
 564     }
 565
 566     return newBigBlock;
 567   }
 568   else
 569   {
 570     /*
 571      * special handling for head of the list
 572      */
 573
 574     if (current->index == index) /* it's already here */
 575       return current;
 576     else if (current->index > index) /* insertion at head of the list */
 577     {
 578       newBigBlock = BIGBLOCKFILE_CreateBlock(index);
 579
 580       if (newBigBlock != NULL)
 581       {
 582         newBigBlock->next = current;
 583         This->headblock = newBigBlock;
 584       }
 585
 586       return newBigBlock;
 587     }
 588   }
 589
 590   /* iterate through rest the list
 591    */
 592   while (current->next != NULL)
 593   {
 594     if (current->next->index == index) /* found it */
 595     {
 596       return current->next;
 597     }
 598     else if (current->next->index > index) /* it's not in the list */
 599     {
 600       newBigBlock = BIGBLOCKFILE_CreateBlock(index);
 601
 602       if (newBigBlock != NULL)
 603       {
 604         newBigBlock->next = current->next;
 605         current->next = newBigBlock;
 606       }
 607
 608       return newBigBlock;
 609     }
 610     else
 611       current = current->next;
 612   }
 613
 614   /*
 615    * insertion at end of the list
 616    */
 617   if (current->next == NULL)
 618   {
 619     newBigBlock = BIGBLOCKFILE_CreateBlock(index);
 620
 621     if (newBigBlock != NULL)
 622     {
 623       newBigBlock->next = NULL;
 624       current->next = newBigBlock;
 625     }
 626
 627     return newBigBlock;
 628   }
 629
 630   return NULL;
 631 }
 632
 633 /******************************************************************************
 634  *      BIGBLOCKFILE_RemoveAllBlocks      [PRIVATE]
 635  *
 636  * Removes all blocks from the blocks list.
 637  */
 638 static void BIGBLOCKFILE_RemoveAllBlocks(
 639   LPBIGBLOCKFILE This)
 640 {
 641   BigBlock *current;
 642
 643   while (This->headblock != NULL)
 644   {
 645     current = This->headblock;
 646     This->headblock = current->next;
 647     HeapFree(GetProcessHeap(), 0, current);
 648   }
 649 }
 650
 651 /******************************************************************************
 652  *      BIGBLOCKFILE_RemoveBlock      [PRIVATE]
 653  *
 654  * Removes the specified block from the blocks list.
 655  */
 656 static void BIGBLOCKFILE_RemoveBlock(
 657   LPBIGBLOCKFILE This,
 658   ULONG          index)
 659 {
 660   BigBlock *current = This->headblock;
 661
 662   /*
 663    * empty list
 664    */
 665   if (current == NULL)
 666     return;
 667
 668   /*
 669    *special case: removing head of list
 670    */
 671   if (current->index == index)
 672   {
 673     /*
 674      * set new head free the old one
 675      */
 676     This->headblock = current->next;
 677     HeapFree(GetProcessHeap(), 0, current);
 678
 679     return;
 680   }
 681
 682   /*
 683    * iterate through rest of the list
 684    */
 685   while (current->next != NULL)
 686   {
 687     if (current->next->index == index) /* found it */
 688     {
 689       /*
 690        * unlink the block and free the block
 691        */
 692       current->next = current->next->next;
 693       HeapFree(GetProcessHeap(), 0, current->next);
 694
 695       return;
 696     }
 697     else
 698     {
 699       /* next node
 700        */
 701       current = current->next;
 702     }
 703   }
 704 }
 705
 706 /******************************************************************************
 707  *      BIGBLOCKFILE_GetBigBlockFromPointer     [PRIVATE]
 708  *
 709  * Given a block pointer, this will return the corresponding block
 710  * from the blocks list.
 711  */
 712 static BigBlock* BIGBLOCKFILE_GetBigBlockFromPointer(
 713   LPBIGBLOCKFILE This,
 714   void*          pBlock)
 715 {
 716   BigBlock *current = This->headblock;
 717
 718   while (current != NULL)
 719   {
 720     if (current->lpBlock == pBlock)
 721     {
 722       break;
 723     }
 724     else
 725       current = current->next;
 726   }
 727
 728   return current;
 729 }
 730
 731 /******************************************************************************
 732  *      BIGBLOCKFILE_GetMappedView      [PRIVATE]
 733  *
 734  * Gets the page requested if it is already mapped.
 735  * If it's not already mapped, this method will map it
 736  */
 737 static void * BIGBLOCKFILE_GetMappedView(
 738   LPBIGBLOCKFILE This,
 739   DWORD          pagenum,
 740   DWORD          desired_access)
 741 {
 742   MappedPage* current = This->maplisthead;
 743   ULONG       count   = 1;
 744   BOOL        found   = FALSE;
 745
 746   assert(This->maplisthead != NULL);
 747
 748   /*
 749    * Search for the page in the list.
 750    */
 751   while ((found == FALSE) && (current->next != NULL))
 752   {
 753     if (current->next->number == pagenum)
 754     {
 755       found = TRUE;
 756
 757       /*
 758        * If it's not already at the head of the list
 759        * move it there.
 760        */
 761       if (current != This->maplisthead)
 762       {
 763         MappedPage* temp = current->next;
 764
 765         current->next = current->next->next;
 766
 767         temp->next = This->maplisthead->next;
 768         This->maplisthead->next = temp;
 769       }
 770     }
 771
 772     /*
 773      * The list is full and we haven't found it.
 774      * Free the last element of the list because we'll add a new
 775      * one at the head.
 776      */
 777     if ((found == FALSE) &&
 778         (count >= NUMBER_OF_MAPPED_PAGES) &&
 779         (current->next != NULL))
 780     {
 781       UnmapViewOfFile(current->next->lpBytes);
 782
 783       HeapFree(GetProcessHeap(), 0, current->next);
 784       current->next = NULL;
 785     }
 786
 787     if (current->next != NULL)
 788       current = current->next;
 789
 790     count++;
 791   }
 792
 793   /*
 794    * Add the page at the head of the list.
 795    */
 796   if (found == FALSE)
 797   {
 798     MappedPage* newMappedPage;
 799     DWORD       numBytesToMap;
 800     DWORD       hioffset  = 0;
 801     DWORD       lowoffset = PAGE_SIZE * pagenum;
 802
 803     newMappedPage = HeapAlloc(GetProcessHeap(), 0, sizeof(MappedPage));
 804
 805     if (newMappedPage == NULL)
 806       return NULL;
 807
 808     newMappedPage->number = pagenum;
 809     newMappedPage->ref = 0;
 810
 811     newMappedPage->next = This->maplisthead->next;
 812     This->maplisthead->next = newMappedPage;
 813
 814     if (((pagenum + 1) * PAGE_SIZE) > This->filesize.s.LowPart)
 815       numBytesToMap = This->filesize.s.LowPart - (pagenum * PAGE_SIZE);
 816     else
 817       numBytesToMap = PAGE_SIZE;
 818
 819     if (This->flProtect == PAGE_READONLY)
 820       desired_access = FILE_MAP_READ;
 821     else
 822       desired_access = FILE_MAP_WRITE;
 823
 824     newMappedPage->lpBytes = MapViewOfFile(This->hfilemap,
 825                                            desired_access,
 826                                            hioffset,
 827                                            lowoffset,
 828                                            numBytesToMap);
 829   }
 830
 831   /*
 832    * The page we want should now be at the head of the list.
 833    */
 834   assert(This->maplisthead->next != NULL);
 835
 836   current = This->maplisthead->next;
 837   current->ref++;
 838
 839   return current->lpBytes;
 840 }
 841
 842 /******************************************************************************
 843  *      BIGBLOCKFILE_ReleaseMappedPage      [PRIVATE]
 844  *
 845  * Decrements the reference count of the mapped page.
 846  */
 847 static void BIGBLOCKFILE_ReleaseMappedPage(
 848   LPBIGBLOCKFILE This,
 849   DWORD          pagenum,
 850   DWORD          access)
 851 {
 852   MappedPage* previous = This->maplisthead;
 853   MappedPage* current;
 854
 855   assert(This->maplisthead->next != NULL);
 856
 857   current = previous->next;
 858
 859   /* search for the page in the list
 860    */
 861   while (current != NULL)
 862   {
 863     if (current->number == pagenum)
 864     {
 865       /* decrement the reference count
 866        */
 867       current->ref--;
 868       return;
 869     }
 870     else
 871     {
 872       previous = current;
 873       current = current->next;
 874     }
 875   }
 876 }
 877
 878 /******************************************************************************
 879  *      BIGBLOCKFILE_FreeAllMappedPages     [PRIVATE]
 880  *
 881  * Unmap all currently mapped pages.
 882  * Empty mapped pages list.
 883  */
 884 static void BIGBLOCKFILE_FreeAllMappedPages(
 885   LPBIGBLOCKFILE This)
 886 {
 887   MappedPage * current = This->maplisthead->next;
 888
 889   while (current != NULL)
 890   {
 891     /* Unmap views.
 892      */
 893     UnmapViewOfFile(current->lpBytes);
 894
 895     /* Free the nodes.
 896      */
 897     This->maplisthead->next = current->next;
 898     HeapFree(GetProcessHeap(), 0, current);
 899
 900     current = This->maplisthead->next;
 901   }
 902 }
 903
 904 /****************************************************************************
 905  *      BIGBLOCKFILE_GetProtectMode
 906  *
 907  * This function will return a protection mode flag for a file-mapping object
 908  * from the open flags of a file.
 909  */
 910 static DWORD BIGBLOCKFILE_GetProtectMode(DWORD openFlags)
 911 {
 912   DWORD flProtect        = PAGE_READONLY;
 913   BOOL bSTGM_WRITE     = ((openFlags & STGM_WRITE) == STGM_WRITE);
 914   BOOL bSTGM_READWRITE = ((openFlags & STGM_READWRITE) == STGM_READWRITE);
 915   BOOL bSTGM_READ      = ! (bSTGM_WRITE || bSTGM_READWRITE);
 916
 917   if (bSTGM_READ)
 918     flProtect = PAGE_READONLY;
 919
 920   if ((bSTGM_WRITE) || (bSTGM_READWRITE))
 921     flProtect = PAGE_READWRITE;
 922
 923   return flProtect;
 924 }
 925
 926