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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, 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 implements the IStream interface and represents a stream
  53  * supported by an HGLOBAL pointer.
  54  */
  55 struct HGLOBALStreamImpl
  56 {
  57   const 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   LONG               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 (IsEqualIID(&IID_IUnknown, riid) ||
 152       IsEqualIID(&IID_ISequentialStream, riid) ||
 153       IsEqualIID(&IID_IStream, riid))
 154   {
 155     *ppvObject = (IStream*)This;
 156   }
 157
 158   /*
 159    * Check that we obtained an interface.
 160    */
 161   if ((*ppvObject)==0)
 162     return E_NOINTERFACE;
 163
 164   /*
 165    * Query Interface always increases the reference count by one when it is
 166    * successful
 167    */
 168   HGLOBALStreamImpl_AddRef(iface);
 169
 170   return S_OK;
 171 }
 172
 173 /***
 174  * This implements the IUnknown method Release for this
 175  * class
 176  */
 177 static ULONG WINAPI HGLOBALStreamImpl_Release(
 178                 IStream* iface)
 179 {
 180   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 181   ULONG newRef;
 182
 183   newRef = InterlockedDecrement(&This->ref);
 184
 185   /*
 186    * If the reference count goes down to 0, perform suicide.
 187    */
 188   if (newRef==0)
 189   {
 190     HGLOBALStreamImpl_Destroy(This);
 191   }
 192
 193   return newRef;
 194 }
 195
 196 /***
 197  * This method is part of the ISequentialStream interface.
 198  *
 199  * If reads a block of information from the stream at the current
 200  * position. It then moves the current position at the end of the
 201  * read block
 202  *
 203  * See the documentation of ISequentialStream for more info.
 204  */
 205 static HRESULT WINAPI HGLOBALStreamImpl_Read(
 206                   IStream*     iface,
 207                   void*          pv,        /* [length_is][size_is][out] */
 208                   ULONG          cb,        /* [in] */
 209                   ULONG*         pcbRead)   /* [out] */
 210 {
 211   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 212
 213   void* supportBuffer;
 214   ULONG bytesReadBuffer;
 215   ULONG bytesToReadFromBuffer;
 216
 217   TRACE("(%p, %p, %d, %p)\n", iface,
 218         pv, cb, pcbRead);
 219
 220   /*
 221    * If the caller is not interested in the nubmer of bytes read,
 222    * we use another buffer to avoid "if" statements in the code.
 223    */
 224   if (pcbRead==0)
 225     pcbRead = &bytesReadBuffer;
 226
 227   /*
 228    * Using the known size of the stream, calculate the number of bytes
 229    * to read from the block chain
 230    */
 231   bytesToReadFromBuffer = min( This->streamSize.u.LowPart - This->currentPosition.u.LowPart, cb);
 232
 233   /*
 234    * Lock the buffer in position and copy the data.
 235    */
 236   supportBuffer = GlobalLock(This->supportHandle);
 237
 238   memcpy(pv, (char *) supportBuffer+This->currentPosition.u.LowPart, bytesToReadFromBuffer);
 239
 240   /*
 241    * Move the current position to the new position
 242    */
 243   This->currentPosition.u.LowPart+=bytesToReadFromBuffer;
 244
 245   /*
 246    * Return the number of bytes read.
 247    */
 248   *pcbRead = bytesToReadFromBuffer;
 249
 250   /*
 251    * Cleanup
 252    */
 253   GlobalUnlock(This->supportHandle);
 254
 255   /*
 256    * Always returns S_OK even if the end of the stream is reached before the
 257    * buffer is filled
 258    */
 259
 260   return S_OK;
 261 }
 262
 263 /***
 264  * This method is part of the ISequentialStream interface.
 265  *
 266  * It writes a block of information to the stream at the current
 267  * position. It then moves the current position at the end of the
 268  * written block. If the stream is too small to fit the block,
 269  * the stream is grown to fit.
 270  *
 271  * See the documentation of ISequentialStream for more info.
 272  */
 273 static HRESULT WINAPI HGLOBALStreamImpl_Write(
 274                   IStream*     iface,
 275                   const void*    pv,          /* [size_is][in] */
 276                   ULONG          cb,          /* [in] */
 277                   ULONG*         pcbWritten)  /* [out] */
 278 {
 279   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 280
 281   void*          supportBuffer;
 282   ULARGE_INTEGER newSize;
 283   ULONG          bytesWritten = 0;
 284
 285   TRACE("(%p, %p, %d, %p)\n", iface, pv, cb, pcbWritten);
 286
 287   /*
 288    * If the caller is not interested in the number of bytes written,
 289    * we use another buffer to avoid "if" statements in the code.
 290    */
 291   if (pcbWritten == 0)
 292     pcbWritten = &bytesWritten;
 293
 294   if (cb == 0)
 295     goto out;
 296
 297   newSize.u.HighPart = 0;
 298   newSize.u.LowPart = This->currentPosition.u.LowPart + cb;
 299
 300   /*
 301    * Verify if we need to grow the stream
 302    */
 303   if (newSize.u.LowPart > This->streamSize.u.LowPart)
 304   {
 305     /* grow stream */
 306     HRESULT hr = IStream_SetSize(iface, newSize);
 307     if (FAILED(hr))
 308     {
 309       ERR("IStream_SetSize failed with error 0x%08x\n", hr);
 310       return hr;
 311     }
 312   }
 313
 314   /*
 315    * Lock the buffer in position and copy the data.
 316    */
 317   supportBuffer = GlobalLock(This->supportHandle);
 318
 319   memcpy((char *) supportBuffer+This->currentPosition.u.LowPart, pv, cb);
 320
 321   /*
 322    * Move the current position to the new position
 323    */
 324   This->currentPosition.u.LowPart+=cb;
 325
 326   /*
 327    * Cleanup
 328    */
 329   GlobalUnlock(This->supportHandle);
 330
 331 out:
 332   /*
 333    * Return the number of bytes read.
 334    */
 335   *pcbWritten = cb;
 336
 337   return S_OK;
 338 }
 339
 340 /***
 341  * This method is part of the IStream interface.
 342  *
 343  * It will move the current stream pointer according to the parameters
 344  * given.
 345  *
 346  * See the documentation of IStream for more info.
 347  */
 348 static HRESULT WINAPI HGLOBALStreamImpl_Seek(
 349                   IStream*      iface,
 350                   LARGE_INTEGER   dlibMove,         /* [in] */
 351                   DWORD           dwOrigin,         /* [in] */
 352                   ULARGE_INTEGER* plibNewPosition) /* [out] */
 353 {
 354   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 355
 356   ULARGE_INTEGER newPosition;
 357
 358   TRACE("(%p, %x%08x, %d, %p)\n", iface, dlibMove.u.HighPart,
 359         dlibMove.u.LowPart, dwOrigin, plibNewPosition);
 360
 361   /*
 362    * The file pointer is moved depending on the given "function"
 363    * parameter.
 364    */
 365   switch (dwOrigin)
 366   {
 367     case STREAM_SEEK_SET:
 368       newPosition.u.HighPart = 0;
 369       newPosition.u.LowPart = 0;
 370       break;
 371     case STREAM_SEEK_CUR:
 372       newPosition = This->currentPosition;
 373       break;
 374     case STREAM_SEEK_END:
 375       newPosition = This->streamSize;
 376       break;
 377     default:
 378       return STG_E_INVALIDFUNCTION;
 379   }
 380
 381   /*
 382    * Move the actual file pointer
 383    * If the file pointer ends-up after the end of the stream, the next Write operation will
 384    * make the file larger. This is how it is documented.
 385    */
 386   if (dlibMove.QuadPart < 0 && newPosition.QuadPart < -dlibMove.QuadPart) return STG_E_INVALIDFUNCTION;
 387
 388   newPosition.QuadPart = RtlLargeIntegerAdd(newPosition.QuadPart, dlibMove.QuadPart);
 389
 390   if (plibNewPosition) *plibNewPosition = newPosition;
 391   This->currentPosition = newPosition;
 392
 393   return S_OK;
 394 }
 395
 396 /***
 397  * This method is part of the IStream interface.
 398  *
 399  * It will change the size of a stream.
 400  *
 401  * TODO: Switch from small blocks to big blocks and vice versa.
 402  *
 403  * See the documentation of IStream for more info.
 404  */
 405 static HRESULT WINAPI HGLOBALStreamImpl_SetSize(
 406                                      IStream*      iface,
 407                                      ULARGE_INTEGER  libNewSize)   /* [in] */
 408 {
 409   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 410   HGLOBAL supportHandle;
 411
 412   TRACE("(%p, %d)\n", iface, libNewSize.u.LowPart);
 413
 414   /*
 415    * HighPart is ignored as shown in tests
 416    */
 417
 418   if (This->streamSize.u.LowPart == libNewSize.u.LowPart)
 419     return S_OK;
 420
 421   /*
 422    * Re allocate the HGlobal to fit the new size of the stream.
 423    */
 424   supportHandle = GlobalReAlloc(This->supportHandle, libNewSize.u.LowPart, 0);
 425
 426   if (supportHandle == 0)
 427     return E_OUTOFMEMORY;
 428
 429   This->supportHandle = supportHandle;
 430   This->streamSize.u.LowPart = libNewSize.u.LowPart;
 431
 432   return S_OK;
 433 }
 434
 435 /***
 436  * This method is part of the IStream interface.
 437  *
 438  * It will copy the 'cb' Bytes to 'pstm' IStream.
 439  *
 440  * See the documentation of IStream for more info.
 441  */
 442 static HRESULT WINAPI HGLOBALStreamImpl_CopyTo(
 443                                     IStream*      iface,
 444                                     IStream*      pstm,         /* [unique][in] */
 445                                     ULARGE_INTEGER  cb,           /* [in] */
 446                                     ULARGE_INTEGER* pcbRead,      /* [out] */
 447                                     ULARGE_INTEGER* pcbWritten)   /* [out] */
 448 {
 449   HRESULT        hr = S_OK;
 450   BYTE           tmpBuffer[128];
 451   ULONG          bytesRead, bytesWritten, copySize;
 452   ULARGE_INTEGER totalBytesRead;
 453   ULARGE_INTEGER totalBytesWritten;
 454
 455   TRACE("(%p, %p, %d, %p, %p)\n", iface, pstm,
 456         cb.u.LowPart, pcbRead, pcbWritten);
 457
 458   /*
 459    * Sanity check
 460    */
 461   if ( pstm == 0 )
 462     return STG_E_INVALIDPOINTER;
 463
 464   totalBytesRead.u.LowPart = totalBytesRead.u.HighPart = 0;
 465   totalBytesWritten.u.LowPart = totalBytesWritten.u.HighPart = 0;
 466
 467   /*
 468    * use stack to store data temporarly
 469    * there is surely more performant way of doing it, for now this basic
 470    * implementation will do the job
 471    */
 472   while ( cb.u.LowPart > 0 )
 473   {
 474     if ( cb.u.LowPart >= 128 )
 475       copySize = 128;
 476     else
 477       copySize = cb.u.LowPart;
 478
 479     hr = IStream_Read(iface, tmpBuffer, copySize, &bytesRead);
 480     if (FAILED(hr))
 481         break;
 482
 483     totalBytesRead.u.LowPart += bytesRead;
 484
 485     if (bytesRead)
 486     {
 487         hr = IStream_Write(pstm, tmpBuffer, bytesRead, &bytesWritten);
 488         if (FAILED(hr))
 489             break;
 490
 491         totalBytesWritten.u.LowPart += bytesWritten;
 492     }
 493
 494     if (bytesRead!=copySize)
 495       cb.u.LowPart = 0;
 496     else
 497       cb.u.LowPart -= bytesRead;
 498   }
 499
 500   /*
 501    * Update number of bytes read and written
 502    */
 503   if (pcbRead)
 504   {
 505     pcbRead->u.LowPart = totalBytesRead.u.LowPart;
 506     pcbRead->u.HighPart = totalBytesRead.u.HighPart;
 507   }
 508
 509   if (pcbWritten)
 510   {
 511     pcbWritten->u.LowPart = totalBytesWritten.u.LowPart;
 512     pcbWritten->u.HighPart = totalBytesWritten.u.HighPart;
 513   }
 514   return hr;
 515 }
 516
 517 /***
 518  * This method is part of the IStream interface.
 519  *
 520  * For streams supported by HGLOBALS, this function does nothing.
 521  * This is what the documentation tells us.
 522  *
 523  * See the documentation of IStream for more info.
 524  */
 525 static HRESULT WINAPI HGLOBALStreamImpl_Commit(
 526                   IStream*      iface,
 527                   DWORD         grfCommitFlags)  /* [in] */
 528 {
 529   return S_OK;
 530 }
 531
 532 /***
 533  * This method is part of the IStream interface.
 534  *
 535  * For streams supported by HGLOBALS, this function does nothing.
 536  * This is what the documentation tells us.
 537  *
 538  * See the documentation of IStream for more info.
 539  */
 540 static HRESULT WINAPI HGLOBALStreamImpl_Revert(
 541                   IStream* iface)
 542 {
 543   return S_OK;
 544 }
 545
 546 /***
 547  * This method is part of the IStream interface.
 548  *
 549  * For streams supported by HGLOBALS, this function does nothing.
 550  * This is what the documentation tells us.
 551  *
 552  * See the documentation of IStream for more info.
 553  */
 554 static HRESULT WINAPI HGLOBALStreamImpl_LockRegion(
 555                   IStream*       iface,
 556                   ULARGE_INTEGER libOffset,   /* [in] */
 557                   ULARGE_INTEGER cb,          /* [in] */
 558                   DWORD          dwLockType)  /* [in] */
 559 {
 560   return STG_E_INVALIDFUNCTION;
 561 }
 562
 563 /*
 564  * This method is part of the IStream interface.
 565  *
 566  * For streams supported by HGLOBALS, this function does nothing.
 567  * This is what the documentation tells us.
 568  *
 569  * See the documentation of IStream for more info.
 570  */
 571 static HRESULT WINAPI HGLOBALStreamImpl_UnlockRegion(
 572                   IStream*       iface,
 573                   ULARGE_INTEGER libOffset,   /* [in] */
 574                   ULARGE_INTEGER cb,          /* [in] */
 575                   DWORD          dwLockType)  /* [in] */
 576 {
 577   return S_OK;
 578 }
 579
 580 /***
 581  * This method is part of the IStream interface.
 582  *
 583  * This method returns information about the current
 584  * stream.
 585  *
 586  * See the documentation of IStream for more info.
 587  */
 588 static HRESULT WINAPI HGLOBALStreamImpl_Stat(
 589                   IStream*     iface,
 590                   STATSTG*     pstatstg,     /* [out] */
 591                   DWORD        grfStatFlag)  /* [in] */
 592 {
 593   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 594
 595   memset(pstatstg, 0, sizeof(STATSTG));
 596
 597   pstatstg->pwcsName = NULL;
 598   pstatstg->type     = STGTY_STREAM;
 599   pstatstg->cbSize   = This->streamSize;
 600
 601   return S_OK;
 602 }
 603
 604 static HRESULT WINAPI HGLOBALStreamImpl_Clone(
 605                   IStream*     iface,
 606                   IStream**    ppstm) /* [out] */
 607 {
 608   ULARGE_INTEGER dummy;
 609   LARGE_INTEGER offset;
 610   HRESULT hr;
 611   HGLOBALStreamImpl* const This=(HGLOBALStreamImpl*)iface;
 612   TRACE(" Cloning %p (deleteOnRelease=%d seek position=%ld)\n",iface,This->deleteOnRelease,(long)This->currentPosition.QuadPart);
 613   hr=CreateStreamOnHGlobal(This->supportHandle, FALSE, ppstm);
 614   if(FAILED(hr))
 615     return hr;
 616   offset.QuadPart=(LONGLONG)This->currentPosition.QuadPart;
 617   HGLOBALStreamImpl_Seek(*ppstm,offset,STREAM_SEEK_SET,&dummy);
 618   return S_OK;
 619 }
 620
 621 /*
 622  * Virtual function table for the HGLOBALStreamImpl class.
 623  */
 624 static const IStreamVtbl HGLOBALStreamImpl_Vtbl =
 625 {
 626     HGLOBALStreamImpl_QueryInterface,
 627     HGLOBALStreamImpl_AddRef,
 628     HGLOBALStreamImpl_Release,
 629     HGLOBALStreamImpl_Read,
 630     HGLOBALStreamImpl_Write,
 631     HGLOBALStreamImpl_Seek,
 632     HGLOBALStreamImpl_SetSize,
 633     HGLOBALStreamImpl_CopyTo,
 634     HGLOBALStreamImpl_Commit,
 635     HGLOBALStreamImpl_Revert,
 636     HGLOBALStreamImpl_LockRegion,
 637     HGLOBALStreamImpl_UnlockRegion,
 638     HGLOBALStreamImpl_Stat,
 639     HGLOBALStreamImpl_Clone
 640 };
 641
 642 /******************************************************************************
 643 ** HGLOBALStreamImpl implementation
 644 */
 645
 646 /***
 647  * This is the constructor for the HGLOBALStreamImpl class.
 648  *
 649  * Params:
 650  *    hGlobal          - Handle that will support the stream. can be NULL.
 651  *    fDeleteOnRelease - Flag set to TRUE if the HGLOBAL will be released
 652  *                       when the IStream object is destroyed.
 653  */
 654 HGLOBALStreamImpl* HGLOBALStreamImpl_Construct(
 655                 HGLOBAL  hGlobal,
 656                 BOOL     fDeleteOnRelease)
 657 {
 658   HGLOBALStreamImpl* newStream;
 659
 660   newStream = HeapAlloc(GetProcessHeap(), 0, sizeof(HGLOBALStreamImpl));
 661
 662   if (newStream!=0)
 663   {
 664     /*
 665      * Set-up the virtual function table and reference count.
 666      */
 667     newStream->lpVtbl = &HGLOBALStreamImpl_Vtbl;
 668     newStream->ref    = 0;
 669
 670     /*
 671      * Initialize the support.
 672      */
 673     newStream->supportHandle = hGlobal;
 674     newStream->deleteOnRelease = fDeleteOnRelease;
 675
 676     /*
 677      * This method will allocate a handle if one is not supplied.
 678      */
 679     if (!newStream->supportHandle)
 680     {
 681       newStream->supportHandle = GlobalAlloc(GMEM_MOVEABLE | GMEM_NODISCARD |
 682                                              GMEM_SHARE, 0);
 683     }
 684
 685     /*
 686      * Start the stream at the beginning.
 687      */
 688     newStream->currentPosition.u.HighPart = 0;
 689     newStream->currentPosition.u.LowPart = 0;
 690
 691     /*
 692      * Initialize the size of the stream to the size of the handle.
 693      */
 694     newStream->streamSize.u.HighPart = 0;
 695     newStream->streamSize.u.LowPart  = GlobalSize(newStream->supportHandle);
 696   }
 697
 698   return newStream;
 699 }
 700
 701
 702 /***********************************************************************
 703  *           CreateStreamOnHGlobal     [OLE32.@]
 704  */
 705 HRESULT WINAPI CreateStreamOnHGlobal(
 706                 HGLOBAL   hGlobal,
 707                 BOOL      fDeleteOnRelease,
 708                 LPSTREAM* ppstm)
 709 {
 710   HGLOBALStreamImpl* newStream;
 711
 712   newStream = HGLOBALStreamImpl_Construct(hGlobal,
 713                                           fDeleteOnRelease);
 714
 715   if (newStream!=NULL)
 716   {
 717     return IUnknown_QueryInterface((IUnknown*)newStream,
 718                                    &IID_IStream,
 719                                    (void**)ppstm);
 720   }
 721
 722   return E_OUTOFMEMORY;
 723 }
 724
 725 /***********************************************************************
 726  *           GetHGlobalFromStream     [OLE32.@]
 727  */
 728 HRESULT WINAPI GetHGlobalFromStream(IStream* pstm, HGLOBAL* phglobal)
 729 {
 730   HGLOBALStreamImpl* pStream;
 731
 732   if (pstm == NULL)
 733     return E_INVALIDARG;
 734
 735   pStream = (HGLOBALStreamImpl*) pstm;
 736
 737   /*
 738    * Verify that the stream object was created with CreateStreamOnHGlobal.
 739    */
 740   if (pStream->lpVtbl == &HGLOBALStreamImpl_Vtbl)
 741     *phglobal = pStream->supportHandle;
 742   else
 743   {
 744     *phglobal = 0;
 745     return E_INVALIDARG;
 746   }
 747
 748   return S_OK;
 749 }