dlls/ole32/hglobalstream.c

   1 /*
   2  * HGLOBAL Stream implementation
   3  *
   4  * This file contains the implementation of the stream interface
   5  * for streams contained supported by an HGLOBAL pointer.
   6  *
   7  * Copyright 1999 Francis Beaudet
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  22  */
  23
  24 #include "config.h"
  25
  26 #include <assert.h>
  27 #include <stdlib.h>
  28 #include <stdio.h>
  29 #include <string.h>
  30
  31 #define NONAMELESSUNION
  32 #define NONAMELESSSTRUCT
  33 #include "windef.h"
  34 #include "objbase.h"
  35 #include "ole2.h"
  36 #include "winbase.h"
  37 #include "winerror.h"
  38 #include "winternl.h"
  39
  40 #include "wine/debug.h"
  41
  42 WINE_DEFAULT_DEBUG_CHANNEL(storage);
  43
  44 /****************************************************************************
  45  * HGLOBALStreamImpl definition.
  46  *
  47  * This class imlements the IStream inteface and represents a stream
  48  * supported by an HGLOBAL pointer.
  49  */
  50 struct HGLOBALStreamImpl
  51 {
  52   ICOM_VFIELD(IStream);  /* Needs to be the first item in the stuct
  53                           * since we want to cast this in a IStream pointer */
  54
  55   /*
  56    * Reference count
  57    */
  58   ULONG              ref;
  59
  60   /*
  61    * Support for the stream
  62    */
  63   HGLOBAL supportHandle;
  64
  65   /*
  66    * This flag is TRUE if the HGLOBAL is destroyed when the stream
  67    * is finally released.
  68    */
  69   BOOL    deleteOnRelease;
  70
  71   /*
  72    * Helper variable that contains the size of the stream
  73    */
  74   ULARGE_INTEGER     streamSize;
  75
  76   /*
  77    * This is the current position of the cursor in the stream
  78    */
  79   ULARGE_INTEGER     currentPosition;
  80 };
  81
  82 typedef struct HGLOBALStreamImpl HGLOBALStreamImpl;
  83
  84 /*
  85  * Method definition for the StgStreamImpl class.
  86  */
  87 HGLOBALStreamImpl* HGLOBALStreamImpl_Construct(
  88                 HGLOBAL  hGlobal,
  89                 BOOL     fDeleteOnRelease);
  90
  91 void HGLOBALStreamImpl_Destroy(
  92                 HGLOBALStreamImpl* This);
  93
  94 void HGLOBALStreamImpl_OpenBlockChain(
  95                 HGLOBALStreamImpl* This);
  96
  97 HRESULT WINAPI HGLOBALStreamImpl_QueryInterface(
  98                 IStream*      iface,
  99                 REFIID         riid,            /* [in] */
 100                 void**         ppvObject);  /* [iid_is][out] */
 101
 102 ULONG WINAPI HGLOBALStreamImpl_AddRef(
 103                 IStream*      iface);
 104
 105 ULONG WINAPI HGLOBALStreamImpl_Release(
 106                 IStream*      iface);
 107
 108 HRESULT WINAPI HGLOBALStreamImpl_Read(
 109                 IStream*      iface,
 110                 void*          pv,        /* [length_is][size_is][out] */
 111                 ULONG          cb,        /* [in] */
 112                 ULONG*         pcbRead);  /* [out] */
 113
 114 HRESULT WINAPI HGLOBALStreamImpl_Write(
 115                 IStream*      iface,
 116                 const void*    pv,          /* [size_is][in] */
 117                 ULONG          cb,          /* [in] */
 118                 ULONG*         pcbWritten); /* [out] */
 119
 120 HRESULT WINAPI HGLOBALStreamImpl_Seek(
 121                 IStream*      iface,
 122                 LARGE_INTEGER   dlibMove,         /* [in] */
 123                 DWORD           dwOrigin,         /* [in] */
 124                 ULARGE_INTEGER* plibNewPosition); /* [out] */
 125
 126 HRESULT WINAPI HGLOBALStreamImpl_SetSize(
 127                 IStream*      iface,
 128                 ULARGE_INTEGER  libNewSize);  /* [in] */
 129
 130 HRESULT WINAPI HGLOBALStreamImpl_CopyTo(
 131                 IStream*      iface,
 132                 IStream*      pstm,         /* [unique][in] */
 133                 ULARGE_INTEGER  cb,           /* [in] */
 134                 ULARGE_INTEGER* pcbRead,      /* [out] */
 135                 ULARGE_INTEGER* pcbWritten);  /* [out] */
 136
 137 HRESULT WINAPI HGLOBALStreamImpl_Commit(
 138                 IStream*      iface,
 139                 DWORD           grfCommitFlags); /* [in] */
 140
 141 HRESULT WINAPI HGLOBALStreamImpl_Revert(
 142                 IStream*  iface);
 143
 144 HRESULT WINAPI HGLOBALStreamImpl_LockRegion(
 145                 IStream*     iface,
 146                 ULARGE_INTEGER libOffset,   /* [in] */
 147                 ULARGE_INTEGER cb,          /* [in] */
 148                 DWORD          dwLockType); /* [in] */
 149
 150 HRESULT WINAPI HGLOBALStreamImpl_UnlockRegion(
 151                 IStream*     iface,
 152                 ULARGE_INTEGER libOffset,   /* [in] */
 153                 ULARGE_INTEGER cb,          /* [in] */
 154                 DWORD          dwLockType); /* [in] */
 155
 156 HRESULT WINAPI HGLOBALStreamImpl_Stat(
 157                 IStream*     iface,
 158                 STATSTG*       pstatstg,     /* [out] */
 159                 DWORD          grfStatFlag); /* [in] */
 160
 161 HRESULT WINAPI HGLOBALStreamImpl_Clone(
 162                 IStream*     iface,
 163                 IStream**    ppstm);       /* [out] */
 164
 165
 166 /*
 167  * Virtual function table for the HGLOBALStreamImpl class.
 168  */
 169 static ICOM_VTABLE(IStream) HGLOBALStreamImpl_Vtbl =
 170 {
 171     ICOM_MSVTABLE_COMPAT_DummyRTTIVALUE
 172     HGLOBALStreamImpl_QueryInterface,
 173     HGLOBALStreamImpl_AddRef,
 174     HGLOBALStreamImpl_Release,
 175     HGLOBALStreamImpl_Read,
 176     HGLOBALStreamImpl_Write,
 177     HGLOBALStreamImpl_Seek,
 178     HGLOBALStreamImpl_SetSize,
 179     HGLOBALStreamImpl_CopyTo,
 180     HGLOBALStreamImpl_Commit,
 181     HGLOBALStreamImpl_Revert,
 182     HGLOBALStreamImpl_LockRegion,
 183     HGLOBALStreamImpl_UnlockRegion,
 184     HGLOBALStreamImpl_Stat,
 185     HGLOBALStreamImpl_Clone
 186 };
 187
 188 /***********************************************************************
 189  *           CreateStreamOnHGlobal     [OLE32.61]
 190  */
 191 HRESULT WINAPI CreateStreamOnHGlobal(
 192                 HGLOBAL   hGlobal,
 193                 BOOL      fDeleteOnRelease,
 194                 LPSTREAM* ppstm)
 195 {
 196   HGLOBALStreamImpl* newStream;
 197
 198   newStream = HGLOBALStreamImpl_Construct(hGlobal,
 199                                           fDeleteOnRelease);
 200
 201   if (newStream!=NULL)
 202   {
 203     return IUnknown_QueryInterface((IUnknown*)newStream,
 204                                    &IID_IStream,
 205                                    (void**)ppstm);
 206   }
 207
 208   return E_OUTOFMEMORY;
 209 }
 210
 211 /***********************************************************************
 212  *           GetHGlobalFromStream     [OLE32.71]
 213  */
 214 HRESULT WINAPI GetHGlobalFromStream(IStream* pstm, HGLOBAL* phglobal)
 215 {
 216   HGLOBALStreamImpl* pStream;
 217
 218   if (pstm == NULL)
 219     return E_INVALIDARG;
 220
 221   pStream = (HGLOBALStreamImpl*) pstm;
 222
 223   /*
 224    * Verify that the stream object was created with CreateStreamOnHGlobal.
 225    */
 226   if (ICOM_VTBL(pStream) == &HGLOBALStreamImpl_Vtbl)
 227     *phglobal = pStream->supportHandle;
 228   else
 229   {
 230     *phglobal = 0;
 231     return E_INVALIDARG;
 232   }
 233
 234   return S_OK;
 235 }
 236
 237 /******************************************************************************
 238 ** HGLOBALStreamImpl implementation
 239 */
 240
 241 /***
 242  * This is the constructor for the HGLOBALStreamImpl class.
 243  *
 244  * Params:
 245  *    hGlobal          - Handle that will support the stream. can be NULL.
 246  *    fDeleteOnRelease - Flag set to TRUE if the HGLOBAL will be released
 247  *                       when the IStream object is destroyed.
 248  */
 249 HGLOBALStreamImpl* HGLOBALStreamImpl_Construct(
 250                 HGLOBAL  hGlobal,
 251                 BOOL     fDeleteOnRelease)
 252 {
 253   HGLOBALStreamImpl* newStream;
 254
 255   newStream = HeapAlloc(GetProcessHeap(), 0, sizeof(HGLOBALStreamImpl));
 256
 257   if (newStream!=0)
 258   {
 259     /*
 260      * Set-up the virtual function table and reference count.
 261      */
 262     ICOM_VTBL(newStream) = &HGLOBALStreamImpl_Vtbl;
 263     newStream->ref    = 0;
 264
 265     /*
 266      * Initialize the support.
 267      */
 268     newStream->supportHandle = hGlobal;
 269     newStream->deleteOnRelease = fDeleteOnRelease;
 270
 271     /*
 272      * This method will allocate a handle if one is not supplied.
 273      */
 274     if (!newStream->supportHandle)
 275     {
 276       newStream->supportHandle = GlobalAlloc(GMEM_MOVEABLE | GMEM_NODISCARD |
 277                                              GMEM_SHARE, 0);
 278     }
 279
 280     /*
 281      * Start the stream at the beginning.
 282      */
 283     newStream->currentPosition.s.HighPart = 0;
 284     newStream->currentPosition.s.LowPart = 0;
 285
 286     /*
 287      * Initialize the size of the stream to the size of the handle.
 288      */
 289     newStream->streamSize.s.HighPart = 0;
 290     newStream->streamSize.s.LowPart  = GlobalSize(newStream->supportHandle);
 291   }
 292
 293   return newStream;
 294 }
 295
 296 /***
 297  * This is the destructor of the HGLOBALStreamImpl class.
 298  *
 299  * This method will clean-up all the resources used-up by the given HGLOBALStreamImpl
 300  * class. The pointer passed-in to this function will be freed and will not
 301  * be valid anymore.
 302  */
 303 void HGLOBALStreamImpl_Destroy(HGLOBALStreamImpl* This)
 304 {
 305   TRACE("(%p)\n", This);
 306
 307   /*
 308    * Release the HGlobal if the constructor asked for that.
 309    */
 310   if (This->deleteOnRelease)
 311   {
 312     GlobalFree(This->supportHandle);
 313     This->supportHandle=0;
 314   }
 315
 316   /*
 317    * Finally, free the memory used-up by the class.
 318    */
 319   HeapFree(GetProcessHeap(), 0, This);
 320 }
 321
 322 /***
 323  * This implements the IUnknown method QueryInterface for this
 324  * class
 325  */
 326 HRESULT WINAPI HGLOBALStreamImpl_QueryInterface(
 327                   IStream*     iface,
 328                   REFIID         riid,        /* [in] */
 329                   void**         ppvObject)   /* [iid_is][out] */
 330 {
 331   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 332
 333   /*
 334    * Perform a sanity check on the parameters.
 335    */
 336   if (ppvObject==0)
 337     return E_INVALIDARG;
 338
 339   /*
 340    * Initialize the return parameter.
 341    */
 342   *ppvObject = 0;
 343
 344   /*
 345    * Compare the riid with the interface IDs implemented by this object.
 346    */
 347   if (memcmp(&IID_IUnknown, riid, sizeof(IID_IUnknown)) == 0)
 348   {
 349     *ppvObject = (IStream*)This;
 350   }
 351   else if (memcmp(&IID_IStream, riid, sizeof(IID_IStream)) == 0)
 352   {
 353     *ppvObject = (IStream*)This;
 354   }
 355
 356   /*
 357    * Check that we obtained an interface.
 358    */
 359   if ((*ppvObject)==0)
 360     return E_NOINTERFACE;
 361
 362   /*
 363    * Query Interface always increases the reference count by one when it is
 364    * successful
 365    */
 366   HGLOBALStreamImpl_AddRef(iface);
 367
 368   return S_OK;
 369 }
 370
 371 /***
 372  * This implements the IUnknown method AddRef for this
 373  * class
 374  */
 375 ULONG WINAPI HGLOBALStreamImpl_AddRef(
 376                 IStream* iface)
 377 {
 378   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 379
 380   This->ref++;
 381
 382   return This->ref;
 383 }
 384
 385 /***
 386  * This implements the IUnknown method Release for this
 387  * class
 388  */
 389 ULONG WINAPI HGLOBALStreamImpl_Release(
 390                 IStream* iface)
 391 {
 392   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 393
 394   ULONG newRef;
 395
 396   This->ref--;
 397
 398   newRef = This->ref;
 399
 400   /*
 401    * If the reference count goes down to 0, perform suicide.
 402    */
 403   if (newRef==0)
 404   {
 405     HGLOBALStreamImpl_Destroy(This);
 406   }
 407
 408   return newRef;
 409 }
 410
 411 /***
 412  * This method is part of the ISequentialStream interface.
 413  *
 414  * If reads a block of information from the stream at the current
 415  * position. It then moves the current position at the end of the
 416  * read block
 417  *
 418  * See the documentation of ISequentialStream for more info.
 419  */
 420 HRESULT WINAPI HGLOBALStreamImpl_Read(
 421                   IStream*     iface,
 422                   void*          pv,        /* [length_is][size_is][out] */
 423                   ULONG          cb,        /* [in] */
 424                   ULONG*         pcbRead)   /* [out] */
 425 {
 426   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 427
 428   void* supportBuffer;
 429   ULONG bytesReadBuffer;
 430   ULONG bytesToReadFromBuffer;
 431
 432   TRACE("(%p, %p, %ld, %p)\n", iface,
 433         pv, cb, pcbRead);
 434
 435   /*
 436    * If the caller is not interested in the nubmer of bytes read,
 437    * we use another buffer to avoid "if" statements in the code.
 438    */
 439   if (pcbRead==0)
 440     pcbRead = &bytesReadBuffer;
 441
 442   /*
 443    * Using the known size of the stream, calculate the number of bytes
 444    * to read from the block chain
 445    */
 446   bytesToReadFromBuffer = min( This->streamSize.s.LowPart - This->currentPosition.s.LowPart, cb);
 447
 448   /*
 449    * Lock the buffer in position and copy the data.
 450    */
 451   supportBuffer = GlobalLock(This->supportHandle);
 452
 453   memcpy(pv, (char *) supportBuffer+This->currentPosition.s.LowPart, bytesToReadFromBuffer);
 454
 455   /*
 456    * Move the current position to the new position
 457    */
 458   This->currentPosition.s.LowPart+=bytesToReadFromBuffer;
 459
 460   /*
 461    * Return the number of bytes read.
 462    */
 463   *pcbRead = bytesToReadFromBuffer;
 464
 465   /*
 466    * Cleanup
 467    */
 468   GlobalUnlock(This->supportHandle);
 469
 470   /*
 471    * The function returns S_OK if the buffer was filled completely
 472    * it returns S_FALSE if the end of the stream is reached before the
 473    * buffer is filled
 474    */
 475   if(*pcbRead == cb)
 476     return S_OK;
 477
 478   return S_FALSE;
 479 }
 480
 481 /***
 482  * This method is part of the ISequentialStream interface.
 483  *
 484  * It writes a block of information to the stream at the current
 485  * position. It then moves the current position at the end of the
 486  * written block. If the stream is too small to fit the block,
 487  * the stream is grown to fit.
 488  *
 489  * See the documentation of ISequentialStream for more info.
 490  */
 491 HRESULT WINAPI HGLOBALStreamImpl_Write(
 492                   IStream*     iface,
 493                   const void*    pv,          /* [size_is][in] */
 494                   ULONG          cb,          /* [in] */
 495                   ULONG*         pcbWritten)  /* [out] */
 496 {
 497   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 498
 499   void*          supportBuffer;
 500   ULARGE_INTEGER newSize;
 501   ULONG          bytesWritten = 0;
 502
 503   TRACE("(%p, %p, %ld, %p)\n", iface,
 504         pv, cb, pcbWritten);
 505
 506   /*
 507    * If the caller is not interested in the number of bytes written,
 508    * we use another buffer to avoid "if" statements in the code.
 509    */
 510   if (pcbWritten == 0)
 511     pcbWritten = &bytesWritten;
 512
 513   if (cb == 0)
 514   {
 515     return S_OK;
 516   }
 517   else
 518   {
 519     newSize.s.HighPart = 0;
 520     newSize.s.LowPart = This->currentPosition.s.LowPart + cb;
 521   }
 522
 523   /*
 524    * Verify if we need to grow the stream
 525    */
 526   if (newSize.s.LowPart > This->streamSize.s.LowPart)
 527   {
 528     /* grow stream */
 529    IStream_SetSize(iface, newSize);
 530   }
 531
 532   /*
 533    * Lock the buffer in position and copy the data.
 534    */
 535   supportBuffer = GlobalLock(This->supportHandle);
 536
 537   memcpy((char *) supportBuffer+This->currentPosition.s.LowPart, pv, cb);
 538
 539   /*
 540    * Move the current position to the new position
 541    */
 542   This->currentPosition.s.LowPart+=cb;
 543
 544   /*
 545    * Return the number of bytes read.
 546    */
 547   *pcbWritten = cb;
 548
 549   /*
 550    * Cleanup
 551    */
 552   GlobalUnlock(This->supportHandle);
 553
 554   return S_OK;
 555 }
 556
 557 /***
 558  * This method is part of the IStream interface.
 559  *
 560  * It will move the current stream pointer according to the parameters
 561  * given.
 562  *
 563  * See the documentation of IStream for more info.
 564  */
 565 HRESULT WINAPI HGLOBALStreamImpl_Seek(
 566                   IStream*      iface,
 567                   LARGE_INTEGER   dlibMove,         /* [in] */
 568                   DWORD           dwOrigin,         /* [in] */
 569                   ULARGE_INTEGER* plibNewPosition) /* [out] */
 570 {
 571   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 572
 573   ULARGE_INTEGER newPosition;
 574
 575   TRACE("(%p, %ld, %ld, %p)\n", iface,
 576         dlibMove.s.LowPart, dwOrigin, plibNewPosition);
 577
 578   /*
 579    * The file pointer is moved depending on the given "function"
 580    * parameter.
 581    */
 582   switch (dwOrigin)
 583   {
 584     case STREAM_SEEK_SET:
 585       newPosition.s.HighPart = 0;
 586       newPosition.s.LowPart = 0;
 587       break;
 588     case STREAM_SEEK_CUR:
 589       newPosition = This->currentPosition;
 590       break;
 591     case STREAM_SEEK_END:
 592       newPosition = This->streamSize;
 593       break;
 594     default:
 595       return STG_E_INVALIDFUNCTION;
 596   }
 597
 598   /*
 599    * Move the actual file pointer
 600    * If the file pointer ends-up after the end of the stream, the next Write operation will
 601    * make the file larger. This is how it is documented.
 602    */
 603   newPosition.QuadPart = RtlLargeIntegerAdd(newPosition.QuadPart, dlibMove.QuadPart);
 604   if (newPosition.QuadPart < 0) return STG_E_INVALIDFUNCTION;
 605
 606   if (plibNewPosition) *plibNewPosition = newPosition;
 607   This->currentPosition = newPosition;
 608
 609   return S_OK;
 610 }
 611
 612 /***
 613  * This method is part of the IStream interface.
 614  *
 615  * It will change the size of a stream.
 616  *
 617  * TODO: Switch from small blocks to big blocks and vice versa.
 618  *
 619  * See the documentation of IStream for more info.
 620  */
 621 HRESULT WINAPI HGLOBALStreamImpl_SetSize(
 622                                      IStream*      iface,
 623                                      ULARGE_INTEGER  libNewSize)   /* [in] */
 624 {
 625   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 626
 627   TRACE("(%p, %ld)\n", iface, libNewSize.s.LowPart);
 628
 629   /*
 630    * As documented.
 631    */
 632   if (libNewSize.s.HighPart != 0)
 633     return STG_E_INVALIDFUNCTION;
 634
 635   if (This->streamSize.s.LowPart == libNewSize.s.LowPart)
 636     return S_OK;
 637
 638   /*
 639    * Re allocate the HGlobal to fit the new size of the stream.
 640    */
 641   This->supportHandle = GlobalReAlloc(This->supportHandle,
 642                                       libNewSize.s.LowPart,
 643                                       0);
 644
 645   This->streamSize.s.LowPart = libNewSize.s.LowPart;
 646
 647   return S_OK;
 648 }
 649
 650 /***
 651  * This method is part of the IStream interface.
 652  *
 653  * It will copy the 'cb' Bytes to 'pstm' IStream.
 654  *
 655  * See the documentation of IStream for more info.
 656  */
 657 HRESULT WINAPI HGLOBALStreamImpl_CopyTo(
 658                                     IStream*      iface,
 659                                     IStream*      pstm,         /* [unique][in] */
 660                                     ULARGE_INTEGER  cb,           /* [in] */
 661                                     ULARGE_INTEGER* pcbRead,      /* [out] */
 662                                     ULARGE_INTEGER* pcbWritten)   /* [out] */
 663 {
 664   HRESULT        hr = S_OK;
 665   BYTE           tmpBuffer[128];
 666   ULONG          bytesRead, bytesWritten, copySize;
 667   ULARGE_INTEGER totalBytesRead;
 668   ULARGE_INTEGER totalBytesWritten;
 669
 670   TRACE("(%p, %p, %ld, %p, %p)\n", iface, pstm,
 671         cb.s.LowPart, pcbRead, pcbWritten);
 672
 673   /*
 674    * Sanity check
 675    */
 676   if ( pstm == 0 )
 677     return STG_E_INVALIDPOINTER;
 678
 679   totalBytesRead.s.LowPart = totalBytesRead.s.HighPart = 0;
 680   totalBytesWritten.s.LowPart = totalBytesWritten.s.HighPart = 0;
 681
 682   /*
 683    * use stack to store data temporarly
 684    * there is surely more performant way of doing it, for now this basic
 685    * implementation will do the job
 686    */
 687   while ( cb.s.LowPart > 0 )
 688   {
 689     if ( cb.s.LowPart >= 128 )
 690       copySize = 128;
 691     else
 692       copySize = cb.s.LowPart;
 693
 694     IStream_Read(iface, tmpBuffer, copySize, &bytesRead);
 695
 696     totalBytesRead.s.LowPart += bytesRead;
 697
 698     IStream_Write(pstm, tmpBuffer, bytesRead, &bytesWritten);
 699
 700     totalBytesWritten.s.LowPart += bytesWritten;
 701
 702     /*
 703      * Check that read & write operations were succesfull
 704      */
 705     if (bytesRead != bytesWritten)
 706     {
 707       hr = STG_E_MEDIUMFULL;
 708       break;
 709     }
 710
 711     if (bytesRead!=copySize)
 712       cb.s.LowPart = 0;
 713     else
 714       cb.s.LowPart -= bytesRead;
 715   }
 716
 717   /*
 718    * Update number of bytes read and written
 719    */
 720   if (pcbRead)
 721   {
 722     pcbRead->s.LowPart = totalBytesRead.s.LowPart;
 723     pcbRead->s.HighPart = totalBytesRead.s.HighPart;
 724   }
 725
 726   if (pcbWritten)
 727   {
 728     pcbWritten->s.LowPart = totalBytesWritten.s.LowPart;
 729     pcbWritten->s.HighPart = totalBytesWritten.s.HighPart;
 730   }
 731   return hr;
 732 }
 733
 734 /***
 735  * This method is part of the IStream interface.
 736  *
 737  * For streams supported by HGLOBALS, this function does nothing.
 738  * This is what the documentation tells us.
 739  *
 740  * See the documentation of IStream for more info.
 741  */
 742 HRESULT WINAPI HGLOBALStreamImpl_Commit(
 743                   IStream*      iface,
 744                   DWORD         grfCommitFlags)  /* [in] */
 745 {
 746   return S_OK;
 747 }
 748
 749 /***
 750  * This method is part of the IStream interface.
 751  *
 752  * For streams supported by HGLOBALS, this function does nothing.
 753  * This is what the documentation tells us.
 754  *
 755  * See the documentation of IStream for more info.
 756  */
 757 HRESULT WINAPI HGLOBALStreamImpl_Revert(
 758                   IStream* iface)
 759 {
 760   return S_OK;
 761 }
 762
 763 /***
 764  * This method is part of the IStream interface.
 765  *
 766  * For streams supported by HGLOBALS, this function does nothing.
 767  * This is what the documentation tells us.
 768  *
 769  * See the documentation of IStream for more info.
 770  */
 771 HRESULT WINAPI HGLOBALStreamImpl_LockRegion(
 772                   IStream*       iface,
 773                   ULARGE_INTEGER libOffset,   /* [in] */
 774                   ULARGE_INTEGER cb,          /* [in] */
 775                   DWORD          dwLockType)  /* [in] */
 776 {
 777   return S_OK;
 778 }
 779
 780 /*
 781  * This method is part of the IStream interface.
 782  *
 783  * For streams supported by HGLOBALS, this function does nothing.
 784  * This is what the documentation tells us.
 785  *
 786  * See the documentation of IStream for more info.
 787  */
 788 HRESULT WINAPI HGLOBALStreamImpl_UnlockRegion(
 789                   IStream*       iface,
 790                   ULARGE_INTEGER libOffset,   /* [in] */
 791                   ULARGE_INTEGER cb,          /* [in] */
 792                   DWORD          dwLockType)  /* [in] */
 793 {
 794   return S_OK;
 795 }
 796
 797 /***
 798  * This method is part of the IStream interface.
 799  *
 800  * This method returns information about the current
 801  * stream.
 802  *
 803  * See the documentation of IStream for more info.
 804  */
 805 HRESULT WINAPI HGLOBALStreamImpl_Stat(
 806                   IStream*     iface,
 807                   STATSTG*     pstatstg,     /* [out] */
 808                   DWORD        grfStatFlag)  /* [in] */
 809 {
 810   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 811
 812   memset(pstatstg, 0, sizeof(STATSTG));
 813
 814   pstatstg->pwcsName = NULL;
 815   pstatstg->type     = STGTY_STREAM;
 816   pstatstg->cbSize   = This->streamSize;
 817
 818   return S_OK;
 819 }
 820
 821 HRESULT WINAPI HGLOBALStreamImpl_Clone(
 822                   IStream*     iface,
 823                   IStream**    ppstm) /* [out] */
 824 {
 825   ULARGE_INTEGER dummy;
 826   LARGE_INTEGER offset;
 827   HRESULT hr;
 828   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 829   TRACE(" Cloning %p (deleteOnRelease=%d seek position=%ld)\n",iface,This->deleteOnRelease,(long)This->currentPosition.QuadPart);
 830   hr=CreateStreamOnHGlobal(This->supportHandle, FALSE, ppstm);
 831   if(FAILED(hr))
 832     return hr;
 833   offset.QuadPart=(LONGLONG)This->currentPosition.QuadPart;
 834   HGLOBALStreamImpl_Seek(*ppstm,offset,STREAM_SEEK_SET,&dummy);
 835   return S_OK;
 836 }