reactos/lib/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 <stdarg.h>
  29 #include <stdio.h>
  30 #include <string.h>
  31
  32 #define COBJMACROS
  33 #define NONAMELESSUNION
  34 #define NONAMELESSSTRUCT
  35
  36 #include "windef.h"
  37 #include "winbase.h"
  38 #include "winuser.h"
  39 #include "objbase.h"
  40 #include "ole2.h"
  41 #include "winerror.h"
  42 #include "winreg.h"
  43 #include "winternl.h"
  44
  45 #include "wine/debug.h"
  46
  47 WINE_DEFAULT_DEBUG_CHANNEL(storage);
  48
  49 /****************************************************************************
  50  * HGLOBALStreamImpl definition.
  51  *
  52  * This class imlements the IStream inteface and represents a stream
  53  * supported by an HGLOBAL pointer.
  54  */
  55 struct HGLOBALStreamImpl
  56 {
  57   IStreamVtbl *lpVtbl;   /* Needs to be the first item in the struct
  58                           * since we want to cast this in an IStream pointer */
  59
  60   /*
  61    * Reference count
  62    */
  63   ULONG              ref;
  64
  65   /*
  66    * Support for the stream
  67    */
  68   HGLOBAL supportHandle;
  69
  70   /*
  71    * This flag is TRUE if the HGLOBAL is destroyed when the stream
  72    * is finally released.
  73    */
  74   BOOL    deleteOnRelease;
  75
  76   /*
  77    * Helper variable that contains the size of the stream
  78    */
  79   ULARGE_INTEGER     streamSize;
  80
  81   /*
  82    * This is the current position of the cursor in the stream
  83    */
  84   ULARGE_INTEGER     currentPosition;
  85 };
  86
  87 typedef struct HGLOBALStreamImpl HGLOBALStreamImpl;
  88
  89 /***
  90  * This is the destructor of the HGLOBALStreamImpl class.
  91  *
  92  * This method will clean-up all the resources used-up by the given HGLOBALStreamImpl
  93  * class. The pointer passed-in to this function will be freed and will not
  94  * be valid anymore.
  95  */
  96 static void HGLOBALStreamImpl_Destroy(HGLOBALStreamImpl* This)
  97 {
  98   TRACE("(%p)\n", This);
  99
 100   /*
 101    * Release the HGlobal if the constructor asked for that.
 102    */
 103   if (This->deleteOnRelease)
 104   {
 105     GlobalFree(This->supportHandle);
 106     This->supportHandle=0;
 107   }
 108
 109   /*
 110    * Finally, free the memory used-up by the class.
 111    */
 112   HeapFree(GetProcessHeap(), 0, This);
 113 }
 114
 115 /***
 116  * This implements the IUnknown method AddRef for this
 117  * class
 118  */
 119 static ULONG WINAPI HGLOBALStreamImpl_AddRef(
 120                 IStream* iface)
 121 {
 122   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 123   return InterlockedIncrement(&This->ref);
 124 }
 125
 126 /***
 127  * This implements the IUnknown method QueryInterface for this
 128  * class
 129  */
 130 static HRESULT WINAPI HGLOBALStreamImpl_QueryInterface(
 131                   IStream*     iface,
 132                   REFIID         riid,        /* [in] */
 133                   void**         ppvObject)   /* [iid_is][out] */
 134 {
 135   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 136
 137   /*
 138    * Perform a sanity check on the parameters.
 139    */
 140   if (ppvObject==0)
 141     return E_INVALIDARG;
 142
 143   /*
 144    * Initialize the return parameter.
 145    */
 146   *ppvObject = 0;
 147
 148   /*
 149    * Compare the riid with the interface IDs implemented by this object.
 150    */
 151   if (memcmp(&IID_IUnknown, riid, sizeof(IID_IUnknown)) == 0)
 152   {
 153     *ppvObject = (IStream*)This;
 154   }
 155   else if (memcmp(&IID_IStream, riid, sizeof(IID_IStream)) == 0)
 156   {
 157     *ppvObject = (IStream*)This;
 158   }
 159
 160   /*
 161    * Check that we obtained an interface.
 162    */
 163   if ((*ppvObject)==0)
 164     return E_NOINTERFACE;
 165
 166   /*
 167    * Query Interface always increases the reference count by one when it is
 168    * successful
 169    */
 170   HGLOBALStreamImpl_AddRef(iface);
 171
 172   return S_OK;
 173 }
 174
 175 /***
 176  * This implements the IUnknown method Release for this
 177  * class
 178  */
 179 static ULONG WINAPI HGLOBALStreamImpl_Release(
 180                 IStream* iface)
 181 {
 182   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 183   ULONG newRef;
 184
 185   newRef = InterlockedDecrement(&This->ref);
 186
 187   /*
 188    * If the reference count goes down to 0, perform suicide.
 189    */
 190   if (newRef==0)
 191   {
 192     HGLOBALStreamImpl_Destroy(This);
 193   }
 194
 195   return newRef;
 196 }
 197
 198 /***
 199  * This method is part of the ISequentialStream interface.
 200  *
 201  * If reads a block of information from the stream at the current
 202  * position. It then moves the current position at the end of the
 203  * read block
 204  *
 205  * See the documentation of ISequentialStream for more info.
 206  */
 207 static HRESULT WINAPI HGLOBALStreamImpl_Read(
 208                   IStream*     iface,
 209                   void*          pv,        /* [length_is][size_is][out] */
 210                   ULONG          cb,        /* [in] */
 211                   ULONG*         pcbRead)   /* [out] */
 212 {
 213   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 214
 215   void* supportBuffer;
 216   ULONG bytesReadBuffer;
 217   ULONG bytesToReadFromBuffer;
 218
 219   TRACE("(%p, %p, %ld, %p)\n", iface,
 220         pv, cb, pcbRead);
 221
 222   /*
 223    * If the caller is not interested in the nubmer of bytes read,
 224    * we use another buffer to avoid "if" statements in the code.
 225    */
 226   if (pcbRead==0)
 227     pcbRead = &bytesReadBuffer;
 228
 229   /*
 230    * Using the known size of the stream, calculate the number of bytes
 231    * to read from the block chain
 232    */
 233   bytesToReadFromBuffer = min( This->streamSize.u.LowPart - This->currentPosition.u.LowPart, cb);
 234
 235   /*
 236    * Lock the buffer in position and copy the data.
 237    */
 238   supportBuffer = GlobalLock(This->supportHandle);
 239
 240   memcpy(pv, (char *) supportBuffer+This->currentPosition.u.LowPart, bytesToReadFromBuffer);
 241
 242   /*
 243    * Move the current position to the new position
 244    */
 245   This->currentPosition.u.LowPart+=bytesToReadFromBuffer;
 246
 247   /*
 248    * Return the number of bytes read.
 249    */
 250   *pcbRead = bytesToReadFromBuffer;
 251
 252   /*
 253    * Cleanup
 254    */
 255   GlobalUnlock(This->supportHandle);
 256
 257   /*
 258    * The function returns S_OK if the buffer was filled completely
 259    * it returns S_FALSE if the end of the stream is reached before the
 260    * buffer is filled
 261    */
 262   if(*pcbRead == cb)
 263     return S_OK;
 264
 265   return S_FALSE;
 266 }
 267
 268 /***
 269  * This method is part of the ISequentialStream interface.
 270  *
 271  * It writes a block of information to the stream at the current
 272  * position. It then moves the current position at the end of the
 273  * written block. If the stream is too small to fit the block,
 274  * the stream is grown to fit.
 275  *
 276  * See the documentation of ISequentialStream for more info.
 277  */
 278 static HRESULT WINAPI HGLOBALStreamImpl_Write(
 279                   IStream*     iface,
 280                   const void*    pv,          /* [size_is][in] */
 281                   ULONG          cb,          /* [in] */
 282                   ULONG*         pcbWritten)  /* [out] */
 283 {
 284   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 285
 286   void*          supportBuffer;
 287   ULARGE_INTEGER newSize;
 288   ULONG          bytesWritten = 0;
 289
 290   TRACE("(%p, %p, %ld, %p)\n", iface,
 291         pv, cb, pcbWritten);
 292
 293   /*
 294    * If the caller is not interested in the number of bytes written,
 295    * we use another buffer to avoid "if" statements in the code.
 296    */
 297   if (pcbWritten == 0)
 298     pcbWritten = &bytesWritten;
 299
 300   if (cb == 0)
 301   {
 302     return S_OK;
 303   }
 304   else
 305   {
 306     newSize.u.HighPart = 0;
 307     newSize.u.LowPart = This->currentPosition.u.LowPart + cb;
 308   }
 309
 310   /*
 311    * Verify if we need to grow the stream
 312    */
 313   if (newSize.u.LowPart > This->streamSize.u.LowPart)
 314   {
 315     /* grow stream */
 316    IStream_SetSize(iface, newSize);
 317   }
 318
 319   /*
 320    * Lock the buffer in position and copy the data.
 321    */
 322   supportBuffer = GlobalLock(This->supportHandle);
 323
 324   memcpy((char *) supportBuffer+This->currentPosition.u.LowPart, pv, cb);
 325
 326   /*
 327    * Move the current position to the new position
 328    */
 329   This->currentPosition.u.LowPart+=cb;
 330
 331   /*
 332    * Return the number of bytes read.
 333    */
 334   *pcbWritten = cb;
 335
 336   /*
 337    * Cleanup
 338    */
 339   GlobalUnlock(This->supportHandle);
 340
 341   return S_OK;
 342 }
 343
 344 /***
 345  * This method is part of the IStream interface.
 346  *
 347  * It will move the current stream pointer according to the parameters
 348  * given.
 349  *
 350  * See the documentation of IStream for more info.
 351  */
 352 static HRESULT WINAPI HGLOBALStreamImpl_Seek(
 353                   IStream*      iface,
 354                   LARGE_INTEGER   dlibMove,         /* [in] */
 355                   DWORD           dwOrigin,         /* [in] */
 356                   ULARGE_INTEGER* plibNewPosition) /* [out] */
 357 {
 358   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 359
 360   ULARGE_INTEGER newPosition;
 361
 362   TRACE("(%p, %lx%08lx, %ld, %p)\n", iface, dlibMove.u.HighPart,
 363         dlibMove.u.LowPart, dwOrigin, plibNewPosition);
 364
 365   /*
 366    * The file pointer is moved depending on the given "function"
 367    * parameter.
 368    */
 369   switch (dwOrigin)
 370   {
 371     case STREAM_SEEK_SET:
 372       newPosition.u.HighPart = 0;
 373       newPosition.u.LowPart = 0;
 374       break;
 375     case STREAM_SEEK_CUR:
 376       newPosition = This->currentPosition;
 377       break;
 378     case STREAM_SEEK_END:
 379       newPosition = This->streamSize;
 380       break;
 381     default:
 382       return STG_E_INVALIDFUNCTION;
 383   }
 384
 385   /*
 386    * Move the actual file pointer
 387    * If the file pointer ends-up after the end of the stream, the next Write operation will
 388    * make the file larger. This is how it is documented.
 389    */
 390   if (dlibMove.QuadPart < 0 && newPosition.QuadPart < -dlibMove.QuadPart) return STG_E_INVALIDFUNCTION;
 391
 392   newPosition.QuadPart = RtlLargeIntegerAdd(newPosition.QuadPart, dlibMove.QuadPart);
 393
 394   if (plibNewPosition) *plibNewPosition = newPosition;
 395   This->currentPosition = newPosition;
 396
 397   return S_OK;
 398 }
 399
 400 /***
 401  * This method is part of the IStream interface.
 402  *
 403  * It will change the size of a stream.
 404  *
 405  * TODO: Switch from small blocks to big blocks and vice versa.
 406  *
 407  * See the documentation of IStream for more info.
 408  */
 409 static HRESULT WINAPI HGLOBALStreamImpl_SetSize(
 410                                      IStream*      iface,
 411                                      ULARGE_INTEGER  libNewSize)   /* [in] */
 412 {
 413   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 414   HGLOBAL supportHandle;
 415
 416   TRACE("(%p, %ld)\n", iface, libNewSize.u.LowPart);
 417
 418   /*
 419    * As documented.
 420    */
 421   if (libNewSize.u.HighPart != 0)
 422     return STG_E_INVALIDFUNCTION;
 423
 424   if (This->streamSize.u.LowPart == libNewSize.u.LowPart)
 425     return S_OK;
 426
 427   /*
 428    * Re allocate the HGlobal to fit the new size of the stream.
 429    */
 430   supportHandle = GlobalReAlloc(This->supportHandle, libNewSize.u.LowPart, 0);
 431
 432   if (supportHandle == 0)
 433     return STG_E_MEDIUMFULL;
 434
 435   This->supportHandle = supportHandle;
 436   This->streamSize.u.LowPart = libNewSize.u.LowPart;
 437
 438   return S_OK;
 439 }
 440
 441 /***
 442  * This method is part of the IStream interface.
 443  *
 444  * It will copy the 'cb' Bytes to 'pstm' IStream.
 445  *
 446  * See the documentation of IStream for more info.
 447  */
 448 static HRESULT WINAPI HGLOBALStreamImpl_CopyTo(
 449                                     IStream*      iface,
 450                                     IStream*      pstm,         /* [unique][in] */
 451                                     ULARGE_INTEGER  cb,           /* [in] */
 452                                     ULARGE_INTEGER* pcbRead,      /* [out] */
 453                                     ULARGE_INTEGER* pcbWritten)   /* [out] */
 454 {
 455   HRESULT        hr = S_OK;
 456   BYTE           tmpBuffer[128];
 457   ULONG          bytesRead, bytesWritten, copySize;
 458   ULARGE_INTEGER totalBytesRead;
 459   ULARGE_INTEGER totalBytesWritten;
 460
 461   TRACE("(%p, %p, %ld, %p, %p)\n", iface, pstm,
 462         cb.u.LowPart, pcbRead, pcbWritten);
 463
 464   /*
 465    * Sanity check
 466    */
 467   if ( pstm == 0 )
 468     return STG_E_INVALIDPOINTER;
 469
 470   totalBytesRead.u.LowPart = totalBytesRead.u.HighPart = 0;
 471   totalBytesWritten.u.LowPart = totalBytesWritten.u.HighPart = 0;
 472
 473   /*
 474    * use stack to store data temporarly
 475    * there is surely more performant way of doing it, for now this basic
 476    * implementation will do the job
 477    */
 478   while ( cb.u.LowPart > 0 )
 479   {
 480     if ( cb.u.LowPart >= 128 )
 481       copySize = 128;
 482     else
 483       copySize = cb.u.LowPart;
 484
 485     IStream_Read(iface, tmpBuffer, copySize, &bytesRead);
 486
 487     totalBytesRead.u.LowPart += bytesRead;
 488
 489     IStream_Write(pstm, tmpBuffer, bytesRead, &bytesWritten);
 490
 491     totalBytesWritten.u.LowPart += bytesWritten;
 492
 493     /*
 494      * Check that read & write operations were succesfull
 495      */
 496     if (bytesRead != bytesWritten)
 497     {
 498       hr = STG_E_MEDIUMFULL;
 499       break;
 500     }
 501
 502     if (bytesRead!=copySize)
 503       cb.u.LowPart = 0;
 504     else
 505       cb.u.LowPart -= bytesRead;
 506   }
 507
 508   /*
 509    * Update number of bytes read and written
 510    */
 511   if (pcbRead)
 512   {
 513     pcbRead->u.LowPart = totalBytesRead.u.LowPart;
 514     pcbRead->u.HighPart = totalBytesRead.u.HighPart;
 515   }
 516
 517   if (pcbWritten)
 518   {
 519     pcbWritten->u.LowPart = totalBytesWritten.u.LowPart;
 520     pcbWritten->u.HighPart = totalBytesWritten.u.HighPart;
 521   }
 522   return hr;
 523 }
 524
 525 /***
 526  * This method is part of the IStream interface.
 527  *
 528  * For streams supported by HGLOBALS, this function does nothing.
 529  * This is what the documentation tells us.
 530  *
 531  * See the documentation of IStream for more info.
 532  */
 533 static HRESULT WINAPI HGLOBALStreamImpl_Commit(
 534                   IStream*      iface,
 535                   DWORD         grfCommitFlags)  /* [in] */
 536 {
 537   return S_OK;
 538 }
 539
 540 /***
 541  * This method is part of the IStream interface.
 542  *
 543  * For streams supported by HGLOBALS, this function does nothing.
 544  * This is what the documentation tells us.
 545  *
 546  * See the documentation of IStream for more info.
 547  */
 548 static HRESULT WINAPI HGLOBALStreamImpl_Revert(
 549                   IStream* iface)
 550 {
 551   return S_OK;
 552 }
 553
 554 /***
 555  * This method is part of the IStream interface.
 556  *
 557  * For streams supported by HGLOBALS, this function does nothing.
 558  * This is what the documentation tells us.
 559  *
 560  * See the documentation of IStream for more info.
 561  */
 562 static HRESULT WINAPI HGLOBALStreamImpl_LockRegion(
 563                   IStream*       iface,
 564                   ULARGE_INTEGER libOffset,   /* [in] */
 565                   ULARGE_INTEGER cb,          /* [in] */
 566                   DWORD          dwLockType)  /* [in] */
 567 {
 568   return S_OK;
 569 }
 570
 571 /*
 572  * This method is part of the IStream interface.
 573  *
 574  * For streams supported by HGLOBALS, this function does nothing.
 575  * This is what the documentation tells us.
 576  *
 577  * See the documentation of IStream for more info.
 578  */
 579 static HRESULT WINAPI HGLOBALStreamImpl_UnlockRegion(
 580                   IStream*       iface,
 581                   ULARGE_INTEGER libOffset,   /* [in] */
 582                   ULARGE_INTEGER cb,          /* [in] */
 583                   DWORD          dwLockType)  /* [in] */
 584 {
 585   return S_OK;
 586 }
 587
 588 /***
 589  * This method is part of the IStream interface.
 590  *
 591  * This method returns information about the current
 592  * stream.
 593  *
 594  * See the documentation of IStream for more info.
 595  */
 596 static HRESULT WINAPI HGLOBALStreamImpl_Stat(
 597                   IStream*     iface,
 598                   STATSTG*     pstatstg,     /* [out] */
 599                   DWORD        grfStatFlag)  /* [in] */
 600 {
 601   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 602
 603   memset(pstatstg, 0, sizeof(STATSTG));
 604
 605   pstatstg->pwcsName = NULL;
 606   pstatstg->type     = STGTY_STREAM;
 607   pstatstg->cbSize   = This->streamSize;
 608
 609   return S_OK;
 610 }
 611
 612 static HRESULT WINAPI HGLOBALStreamImpl_Clone(
 613                   IStream*     iface,
 614                   IStream**    ppstm) /* [out] */
 615 {
 616   ULARGE_INTEGER dummy;
 617   LARGE_INTEGER offset;
 618   HRESULT hr;
 619   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 620   TRACE(" Cloning %p (deleteOnRelease=%d seek position=%ld)\n",iface,This->deleteOnRelease,(long)This->currentPosition.QuadPart);
 621   hr=CreateStreamOnHGlobal(This->supportHandle, FALSE, ppstm);
 622   if(FAILED(hr))
 623     return hr;
 624   offset.QuadPart=(LONGLONG)This->currentPosition.QuadPart;
 625   HGLOBALStreamImpl_Seek(*ppstm,offset,STREAM_SEEK_SET,&dummy);
 626   return S_OK;
 627 }
 628
 629 /*
 630  * Virtual function table for the HGLOBALStreamImpl class.
 631  */
 632 static IStreamVtbl HGLOBALStreamImpl_Vtbl =
 633 {
 634     HGLOBALStreamImpl_QueryInterface,
 635     HGLOBALStreamImpl_AddRef,
 636     HGLOBALStreamImpl_Release,
 637     HGLOBALStreamImpl_Read,
 638     HGLOBALStreamImpl_Write,
 639     HGLOBALStreamImpl_Seek,
 640     HGLOBALStreamImpl_SetSize,
 641     HGLOBALStreamImpl_CopyTo,
 642     HGLOBALStreamImpl_Commit,
 643     HGLOBALStreamImpl_Revert,
 644     HGLOBALStreamImpl_LockRegion,
 645     HGLOBALStreamImpl_UnlockRegion,
 646     HGLOBALStreamImpl_Stat,
 647     HGLOBALStreamImpl_Clone
 648 };
 649
 650 /******************************************************************************
 651 ** HGLOBALStreamImpl implementation
 652 */
 653
 654 /***
 655  * This is the constructor for the HGLOBALStreamImpl class.
 656  *
 657  * Params:
 658  *    hGlobal          - Handle that will support the stream. can be NULL.
 659  *    fDeleteOnRelease - Flag set to TRUE if the HGLOBAL will be released
 660  *                       when the IStream object is destroyed.
 661  */
 662 HGLOBALStreamImpl* HGLOBALStreamImpl_Construct(
 663                 HGLOBAL  hGlobal,
 664                 BOOL     fDeleteOnRelease)
 665 {
 666   HGLOBALStreamImpl* newStream;
 667
 668   newStream = HeapAlloc(GetProcessHeap(), 0, sizeof(HGLOBALStreamImpl));
 669
 670   if (newStream!=0)
 671   {
 672     /*
 673      * Set-up the virtual function table and reference count.
 674      */
 675     newStream->lpVtbl = &HGLOBALStreamImpl_Vtbl;
 676     newStream->ref    = 0;
 677
 678     /*
 679      * Initialize the support.
 680      */
 681     newStream->supportHandle = hGlobal;
 682     newStream->deleteOnRelease = fDeleteOnRelease;
 683
 684     /*
 685      * This method will allocate a handle if one is not supplied.
 686      */
 687     if (!newStream->supportHandle)
 688     {
 689       newStream->supportHandle = GlobalAlloc(GMEM_MOVEABLE | GMEM_NODISCARD |
 690                                              GMEM_SHARE, 0);
 691     }
 692
 693     /*
 694      * Start the stream at the beginning.
 695      */
 696     newStream->currentPosition.u.HighPart = 0;
 697     newStream->currentPosition.u.LowPart = 0;
 698
 699     /*
 700      * Initialize the size of the stream to the size of the handle.
 701      */
 702     newStream->streamSize.u.HighPart = 0;
 703     newStream->streamSize.u.LowPart  = GlobalSize(newStream->supportHandle);
 704   }
 705
 706   return newStream;
 707 }
 708
 709
 710 /***********************************************************************
 711  *           CreateStreamOnHGlobal     [OLE32.@]
 712  */
 713 HRESULT WINAPI CreateStreamOnHGlobal(
 714                 HGLOBAL   hGlobal,
 715                 BOOL      fDeleteOnRelease,
 716                 LPSTREAM* ppstm)
 717 {
 718   HGLOBALStreamImpl* newStream;
 719
 720   newStream = HGLOBALStreamImpl_Construct(hGlobal,
 721                                           fDeleteOnRelease);
 722
 723   if (newStream!=NULL)
 724   {
 725     return IUnknown_QueryInterface((IUnknown*)newStream,
 726                                    &IID_IStream,
 727                                    (void**)ppstm);
 728   }
 729
 730   return E_OUTOFMEMORY;
 731 }
 732
 733 /***********************************************************************
 734  *           GetHGlobalFromStream     [OLE32.@]
 735  */
 736 HRESULT WINAPI GetHGlobalFromStream(IStream* pstm, HGLOBAL* phglobal)
 737 {
 738   HGLOBALStreamImpl* pStream;
 739
 740   if (pstm == NULL)
 741     return E_INVALIDARG;
 742
 743   pStream = (HGLOBALStreamImpl*) pstm;
 744
 745   /*
 746    * Verify that the stream object was created with CreateStreamOnHGlobal.
 747    */
 748   if (pStream->lpVtbl == &HGLOBALStreamImpl_Vtbl)
 749     *phglobal = pStream->supportHandle;
 750   else
 751   {
 752     *phglobal = 0;
 753     return E_INVALIDARG;
 754   }
 755
 756   return S_OK;
 757 }