source: trunk/src/ole32/stg_stream.c@ 8441

Last change on this file since 8441 was 8441, checked in by sandervl, 23 years ago

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1/*
2 * Compound Storage (32 bit version)
3 * Stream implementation
4 *
5 * This file contains the implementation of the stream interface
6 * for streams contained in a compound storage.
7 *
8 * Copyright 1999 Francis Beaudet
9 * Copyright 1999 Thuy Nguyen
10 *
11 * This library is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this library; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24 */
25#include <assert.h>
26#include <stdlib.h>
27#include <stdio.h>
28#include <string.h>
29
30#include "winbase.h"
31#include "winerror.h"
32#include "ntddk.h"
33#include "wine/debug.h"
34
35#include "storage32.h"
36
37WINE_DEFAULT_DEBUG_CHANNEL(storage);
38
39
40/*
41 * Virtual function table for the StgStreamImpl class.
42 */
43static ICOM_VTABLE(IStream) StgStreamImpl_Vtbl =
44{
45 ICOM_MSVTABLE_COMPAT_DummyRTTIVALUE
46 StgStreamImpl_QueryInterface,
47 StgStreamImpl_AddRef,
48 StgStreamImpl_Release,
49 StgStreamImpl_Read,
50 StgStreamImpl_Write,
51 StgStreamImpl_Seek,
52 StgStreamImpl_SetSize,
53 StgStreamImpl_CopyTo,
54 StgStreamImpl_Commit,
55 StgStreamImpl_Revert,
56 StgStreamImpl_LockRegion,
57 StgStreamImpl_UnlockRegion,
58 StgStreamImpl_Stat,
59 StgStreamImpl_Clone
60};
61
62/******************************************************************************
63** StgStreamImpl implementation
64*/
65
66/***
67 * This is the constructor for the StgStreamImpl class.
68 *
69 * Params:
70 * parentStorage - Pointer to the storage that contains the stream to open
71 * ownerProperty - Index of the property that points to this stream.
72 */
73StgStreamImpl* StgStreamImpl_Construct(
74 StorageBaseImpl* parentStorage,
75 DWORD grfMode,
76 ULONG ownerProperty)
77{
78 StgStreamImpl* newStream;
79
80 newStream = HeapAlloc(GetProcessHeap(), 0, sizeof(StgStreamImpl));
81
82 if (newStream!=0)
83 {
84 /*
85 * Set-up the virtual function table and reference count.
86 */
87 ICOM_VTBL(newStream) = &StgStreamImpl_Vtbl;
88 newStream->ref = 0;
89
90 /*
91 * We want to nail-down the reference to the storage in case the
92 * stream out-lives the storage in the client application.
93 */
94 newStream->parentStorage = parentStorage;
95 IStorage_AddRef((IStorage*)newStream->parentStorage);
96
97 newStream->grfMode = grfMode;
98 newStream->ownerProperty = ownerProperty;
99
100 /*
101 * Start the stream at the beginning.
102 */
103 newStream->currentPosition.s.HighPart = 0;
104 newStream->currentPosition.s.LowPart = 0;
105
106 /*
107 * Initialize the rest of the data.
108 */
109 newStream->streamSize.s.HighPart = 0;
110 newStream->streamSize.s.LowPart = 0;
111 newStream->bigBlockChain = 0;
112 newStream->smallBlockChain = 0;
113
114 /*
115 * Read the size from the property and determine if the blocks forming
116 * this stream are large or small.
117 */
118 StgStreamImpl_OpenBlockChain(newStream);
119 }
120
121 return newStream;
122}
123
124/***
125 * This is the destructor of the StgStreamImpl class.
126 *
127 * This method will clean-up all the resources used-up by the given StgStreamImpl
128 * class. The pointer passed-in to this function will be freed and will not
129 * be valid anymore.
130 */
131void StgStreamImpl_Destroy(StgStreamImpl* This)
132{
133 TRACE("(%p)\n", This);
134
135 /*
136 * Release the reference we are holding on the parent storage.
137 */
138 IStorage_Release((IStorage*)This->parentStorage);
139 This->parentStorage = 0;
140
141 /*
142 * Make sure we clean-up the block chain stream objects that we were using.
143 */
144 if (This->bigBlockChain != 0)
145 {
146 BlockChainStream_Destroy(This->bigBlockChain);
147 This->bigBlockChain = 0;
148 }
149
150 if (This->smallBlockChain != 0)
151 {
152 SmallBlockChainStream_Destroy(This->smallBlockChain);
153 This->smallBlockChain = 0;
154 }
155
156 /*
157 * Finally, free the memory used-up by the class.
158 */
159 HeapFree(GetProcessHeap(), 0, This);
160}
161
162/***
163 * This implements the IUnknown method QueryInterface for this
164 * class
165 */
166HRESULT WINAPI StgStreamImpl_QueryInterface(
167 IStream* iface,
168 REFIID riid, /* [in] */
169 void** ppvObject) /* [iid_is][out] */
170{
171 StgStreamImpl* const This=(StgStreamImpl*)iface;
172
173 /*
174 * Perform a sanity check on the parameters.
175 */
176 if (ppvObject==0)
177 return E_INVALIDARG;
178
179 /*
180 * Initialize the return parameter.
181 */
182 *ppvObject = 0;
183
184 /*
185 * Compare the riid with the interface IDs implemented by this object.
186 */
187 if (memcmp(&IID_IUnknown, riid, sizeof(IID_IUnknown)) == 0)
188 {
189 *ppvObject = (IStream*)This;
190 }
191 else if (memcmp(&IID_IStream, riid, sizeof(IID_IStream)) == 0)
192 {
193 *ppvObject = (IStream*)This;
194 }
195
196 /*
197 * Check that we obtained an interface.
198 */
199 if ((*ppvObject)==0)
200 return E_NOINTERFACE;
201
202 /*
203 * Query Interface always increases the reference count by one when it is
204 * successful
205 */
206 StgStreamImpl_AddRef(iface);
207
208 return S_OK;;
209}
210
211/***
212 * This implements the IUnknown method AddRef for this
213 * class
214 */
215ULONG WINAPI StgStreamImpl_AddRef(
216 IStream* iface)
217{
218 StgStreamImpl* const This=(StgStreamImpl*)iface;
219
220 This->ref++;
221
222 return This->ref;
223}
224
225/***
226 * This implements the IUnknown method Release for this
227 * class
228 */
229ULONG WINAPI StgStreamImpl_Release(
230 IStream* iface)
231{
232 StgStreamImpl* const This=(StgStreamImpl*)iface;
233
234 ULONG newRef;
235
236 This->ref--;
237
238 newRef = This->ref;
239
240 /*
241 * If the reference count goes down to 0, perform suicide.
242 */
243 if (newRef==0)
244 {
245 StgStreamImpl_Destroy(This);
246 }
247
248 return newRef;
249}
250
251/***
252 * This method will open the block chain pointed by the property
253 * that describes the stream.
254 * If the stream's size is null, no chain is opened.
255 */
256void StgStreamImpl_OpenBlockChain(
257 StgStreamImpl* This)
258{
259 StgProperty curProperty;
260 BOOL readSucessful;
261
262 /*
263 * Make sure no old object is left over.
264 */
265 if (This->smallBlockChain != 0)
266 {
267 SmallBlockChainStream_Destroy(This->smallBlockChain);
268 This->smallBlockChain = 0;
269 }
270
271 if (This->bigBlockChain != 0)
272 {
273 BlockChainStream_Destroy(This->bigBlockChain);
274 This->bigBlockChain = 0;
275 }
276
277 /*
278 * Read the information from the property.
279 */
280 readSucessful = StorageImpl_ReadProperty(This->parentStorage->ancestorStorage,
281 This->ownerProperty,
282 &curProperty);
283
284 if (readSucessful)
285 {
286 This->streamSize = curProperty.size;
287
288 /*
289 * This code supports only streams that are <32 bits in size.
290 */
291 assert(This->streamSize.s.HighPart == 0);
292
293 if(curProperty.startingBlock == BLOCK_END_OF_CHAIN)
294 {
295 assert( (This->streamSize.s.HighPart == 0) && (This->streamSize.s.LowPart == 0) );
296 }
297 else
298 {
299 if ( (This->streamSize.s.HighPart == 0) &&
300 (This->streamSize.s.LowPart < LIMIT_TO_USE_SMALL_BLOCK) )
301 {
302 This->smallBlockChain = SmallBlockChainStream_Construct(
303 This->parentStorage->ancestorStorage,
304 This->ownerProperty);
305 }
306 else
307 {
308 This->bigBlockChain = BlockChainStream_Construct(
309 This->parentStorage->ancestorStorage,
310 NULL,
311 This->ownerProperty);
312 }
313 }
314 }
315}
316
317/***
318 * This method is part of the ISequentialStream interface.
319 *
320 * It reads a block of information from the stream at the current
321 * position. It then moves the current position at the end of the
322 * read block
323 *
324 * See the documentation of ISequentialStream for more info.
325 */
326HRESULT WINAPI StgStreamImpl_Read(
327 IStream* iface,
328 void* pv, /* [length_is][size_is][out] */
329 ULONG cb, /* [in] */
330 ULONG* pcbRead) /* [out] */
331{
332 StgStreamImpl* const This=(StgStreamImpl*)iface;
333
334 ULONG bytesReadBuffer;
335 ULONG bytesToReadFromBuffer;
336 HRESULT res = S_FALSE;
337
338 TRACE("(%p, %p, %ld, %p)\n",
339 iface, pv, cb, pcbRead);
340
341 /*
342 * If the caller is not interested in the number of bytes read,
343 * we use another buffer to avoid "if" statements in the code.
344 */
345 if (pcbRead==0)
346 pcbRead = &bytesReadBuffer;
347
348 /*
349 * Using the known size of the stream, calculate the number of bytes
350 * to read from the block chain
351 */
352 bytesToReadFromBuffer = min( This->streamSize.s.LowPart - This->currentPosition.s.LowPart, cb);
353
354 /*
355 * Depending on the type of chain that was opened when the stream was constructed,
356 * we delegate the work to the method that reads the block chains.
357 */
358 if (This->smallBlockChain!=0)
359 {
360 SmallBlockChainStream_ReadAt(This->smallBlockChain,
361 This->currentPosition,
362 bytesToReadFromBuffer,
363 pv,
364 pcbRead);
365
366 }
367 else if (This->bigBlockChain!=0)
368 {
369 BlockChainStream_ReadAt(This->bigBlockChain,
370 This->currentPosition,
371 bytesToReadFromBuffer,
372 pv,
373 pcbRead);
374 }
375 else
376 {
377 /*
378 * Small and big block chains are both NULL. This case will happen
379 * when a stream starts with BLOCK_END_OF_CHAIN and has size zero.
380 */
381
382 *pcbRead = 0;
383 res = S_OK;
384 goto end;
385 }
386
387 /*
388 * We should always be able to read the proper amount of data from the
389 * chain.
390 */
391 assert(bytesToReadFromBuffer == *pcbRead);
392
393 /*
394 * Advance the pointer for the number of positions read.
395 */
396 This->currentPosition.s.LowPart += *pcbRead;
397
398 if(*pcbRead != cb)
399 {
400 WARN("read %ld instead of the required %ld bytes !\n", *pcbRead, cb);
401 /*
402 * this used to return S_FALSE, however MSDN docu says that an app should
403 * be prepared to handle error in case of stream end reached, as *some*
404 * implementations *might* return an error (IOW: most do *not*).
405 * As some program fails on returning S_FALSE, I better use S_OK here.
406 */
407 res = S_OK;
408 }
409 else
410 res = S_OK;
411
412end:
413 TRACE("<-- %08lx\n", res);
414 return res;
415}
416
417/***
418 * This method is part of the ISequentialStream interface.
419 *
420 * It writes a block of information to the stream at the current
421 * position. It then moves the current position at the end of the
422 * written block. If the stream is too small to fit the block,
423 * the stream is grown to fit.
424 *
425 * See the documentation of ISequentialStream for more info.
426 */
427HRESULT WINAPI StgStreamImpl_Write(
428 IStream* iface,
429 const void* pv, /* [size_is][in] */
430 ULONG cb, /* [in] */
431 ULONG* pcbWritten) /* [out] */
432{
433 StgStreamImpl* const This=(StgStreamImpl*)iface;
434
435 ULARGE_INTEGER newSize;
436 ULONG bytesWritten = 0;
437
438 TRACE("(%p, %p, %ld, %p)\n",
439 iface, pv, cb, pcbWritten);
440
441 /*
442 * Do we have permission to write to this stream?
443 */
444 if (!(This->grfMode & (STGM_WRITE | STGM_READWRITE))) {
445 return STG_E_ACCESSDENIED;
446 }
447
448 /*
449 * If the caller is not interested in the number of bytes written,
450 * we use another buffer to avoid "if" statements in the code.
451 */
452 if (pcbWritten == 0)
453 pcbWritten = &bytesWritten;
454
455 /*
456 * Initialize the out parameter
457 */
458 *pcbWritten = 0;
459
460 if (cb == 0)
461 {
462 return S_OK;
463 }
464 else
465 {
466 newSize.s.HighPart = 0;
467 newSize.s.LowPart = This->currentPosition.s.LowPart + cb;
468 }
469
470 /*
471 * Verify if we need to grow the stream
472 */
473 if (newSize.s.LowPart > This->streamSize.s.LowPart)
474 {
475 /* grow stream */
476 IStream_SetSize(iface, newSize);
477 }
478
479 /*
480 * Depending on the type of chain that was opened when the stream was constructed,
481 * we delegate the work to the method that readwrites to the block chains.
482 */
483 if (This->smallBlockChain!=0)
484 {
485 SmallBlockChainStream_WriteAt(This->smallBlockChain,
486 This->currentPosition,
487 cb,
488 pv,
489 pcbWritten);
490
491 }
492 else if (This->bigBlockChain!=0)
493 {
494 BlockChainStream_WriteAt(This->bigBlockChain,
495 This->currentPosition,
496 cb,
497 pv,
498 pcbWritten);
499 }
500 else
501 assert(FALSE);
502
503 /*
504 * Advance the position pointer for the number of positions written.
505 */
506 This->currentPosition.s.LowPart += *pcbWritten;
507
508 return S_OK;
509}
510
511/***
512 * This method is part of the IStream interface.
513 *
514 * It will move the current stream pointer according to the parameters
515 * given.
516 *
517 * See the documentation of IStream for more info.
518 */
519HRESULT WINAPI StgStreamImpl_Seek(
520 IStream* iface,
521 LARGE_INTEGER dlibMove, /* [in] */
522 DWORD dwOrigin, /* [in] */
523 ULARGE_INTEGER* plibNewPosition) /* [out] */
524{
525 StgStreamImpl* const This=(StgStreamImpl*)iface;
526
527 ULARGE_INTEGER newPosition;
528
529 TRACE("(%p, %ld, %ld, %p)\n",
530 iface, dlibMove.s.LowPart, dwOrigin, plibNewPosition);
531
532 /*
533 * The caller is allowed to pass in NULL as the new position return value.
534 * If it happens, we assign it to a dynamic variable to avoid special cases
535 * in the code below.
536 */
537 if (plibNewPosition == 0)
538 {
539 plibNewPosition = &newPosition;
540 }
541
542 /*
543 * The file pointer is moved depending on the given "function"
544 * parameter.
545 */
546 switch (dwOrigin)
547 {
548 case STREAM_SEEK_SET:
549 plibNewPosition->s.HighPart = 0;
550 plibNewPosition->s.LowPart = 0;
551 break;
552 case STREAM_SEEK_CUR:
553 *plibNewPosition = This->currentPosition;
554 break;
555 case STREAM_SEEK_END:
556 *plibNewPosition = This->streamSize;
557 break;
558 default:
559 return STG_E_INVALIDFUNCTION;
560 }
561
562#if defined(__WIN32OS2__) && defined(__IBMC__)
563 *((LARGE_INTEGER*)&plibNewPosition )= RtlpLargeIntegerAdd( (LARGE_INTEGER *)plibNewPosition, &dlibMove );
564#else
565 plibNewPosition->QuadPart = RtlLargeIntegerAdd( plibNewPosition->QuadPart, dlibMove.QuadPart );
566#endif
567
568 /*
569 * tell the caller what we calculated
570 */
571 This->currentPosition = *plibNewPosition;
572
573 return S_OK;
574}
575
576/***
577 * This method is part of the IStream interface.
578 *
579 * It will change the size of a stream.
580 *
581 * TODO: Switch from small blocks to big blocks and vice versa.
582 *
583 * See the documentation of IStream for more info.
584 */
585HRESULT WINAPI StgStreamImpl_SetSize(
586 IStream* iface,
587 ULARGE_INTEGER libNewSize) /* [in] */
588{
589 StgStreamImpl* const This=(StgStreamImpl*)iface;
590
591 StgProperty curProperty;
592 BOOL Success;
593
594 TRACE("(%p, %ld)\n", iface, libNewSize.s.LowPart);
595
596 /*
597 * As documented.
598 */
599 if (libNewSize.s.HighPart != 0)
600 return STG_E_INVALIDFUNCTION;
601
602 /*
603 * Do we have permission?
604 */
605 if (!(This->grfMode & (STGM_WRITE | STGM_READWRITE)))
606 return STG_E_ACCESSDENIED;
607
608 if (This->streamSize.s.LowPart == libNewSize.s.LowPart)
609 return S_OK;
610
611 /*
612 * This will happen if we're creating a stream
613 */
614 if ((This->smallBlockChain == 0) && (This->bigBlockChain == 0))
615 {
616 if (libNewSize.s.LowPart < LIMIT_TO_USE_SMALL_BLOCK)
617 {
618 This->smallBlockChain = SmallBlockChainStream_Construct(
619 This->parentStorage->ancestorStorage,
620 This->ownerProperty);
621 }
622 else
623 {
624 This->bigBlockChain = BlockChainStream_Construct(
625 This->parentStorage->ancestorStorage,
626 NULL,
627 This->ownerProperty);
628 }
629 }
630
631 /*
632 * Read this stream's property to see if it's small blocks or big blocks
633 */
634 Success = StorageImpl_ReadProperty(This->parentStorage->ancestorStorage,
635 This->ownerProperty,
636 &curProperty);
637 /*
638 * Determine if we have to switch from small to big blocks or vice versa
639 */
640 if ( (This->smallBlockChain!=0) &&
641 (curProperty.size.s.LowPart < LIMIT_TO_USE_SMALL_BLOCK) )
642 {
643 if (libNewSize.s.LowPart >= LIMIT_TO_USE_SMALL_BLOCK)
644 {
645 /*
646 * Transform the small block chain into a big block chain
647 */
648 This->bigBlockChain = Storage32Impl_SmallBlocksToBigBlocks(
649 This->parentStorage->ancestorStorage,
650 &This->smallBlockChain);
651 }
652 }
653
654 if (This->smallBlockChain!=0)
655 {
656 Success = SmallBlockChainStream_SetSize(This->smallBlockChain, libNewSize);
657 }
658 else
659 {
660 Success = BlockChainStream_SetSize(This->bigBlockChain, libNewSize);
661 }
662
663 /*
664 * Write the new information about this stream to the property
665 */
666 Success = StorageImpl_ReadProperty(This->parentStorage->ancestorStorage,
667 This->ownerProperty,
668 &curProperty);
669
670 curProperty.size.s.HighPart = libNewSize.s.HighPart;
671 curProperty.size.s.LowPart = libNewSize.s.LowPart;
672
673 if (Success)
674 {
675 StorageImpl_WriteProperty(This->parentStorage->ancestorStorage,
676 This->ownerProperty,
677 &curProperty);
678 }
679
680 This->streamSize = libNewSize;
681
682 return S_OK;
683}
684
685/***
686 * This method is part of the IStream interface.
687 *
688 * It will copy the 'cb' Bytes to 'pstm' IStream.
689 *
690 * See the documentation of IStream for more info.
691 */
692HRESULT WINAPI StgStreamImpl_CopyTo(
693 IStream* iface,
694 IStream* pstm, /* [unique][in] */
695 ULARGE_INTEGER cb, /* [in] */
696 ULARGE_INTEGER* pcbRead, /* [out] */
697 ULARGE_INTEGER* pcbWritten) /* [out] */
698{
699 HRESULT hr = S_OK;
700 BYTE tmpBuffer[128];
701 ULONG bytesRead, bytesWritten, copySize;
702 ULARGE_INTEGER totalBytesRead;
703 ULARGE_INTEGER totalBytesWritten;
704
705 TRACE("(%p, %p, %ld, %p, %p)\n",
706 iface, pstm, cb.s.LowPart, pcbRead, pcbWritten);
707
708 /*
709 * Sanity check
710 */
711 if ( pstm == 0 )
712 return STG_E_INVALIDPOINTER;
713
714 totalBytesRead.s.LowPart = totalBytesRead.s.HighPart = 0;
715 totalBytesWritten.s.LowPart = totalBytesWritten.s.HighPart = 0;
716
717 /*
718 * use stack to store data temporarily
719 * there is surely a more performant way of doing it, for now this basic
720 * implementation will do the job
721 */
722 while ( cb.s.LowPart > 0 )
723 {
724 if ( cb.s.LowPart >= 128 )
725 copySize = 128;
726 else
727 copySize = cb.s.LowPart;
728
729 IStream_Read(iface, tmpBuffer, copySize, &bytesRead);
730
731 totalBytesRead.s.LowPart += bytesRead;
732
733 IStream_Write(pstm, tmpBuffer, bytesRead, &bytesWritten);
734
735 totalBytesWritten.s.LowPart += bytesWritten;
736
737 /*
738 * Check that read & write operations were successful
739 */
740 if (bytesRead != bytesWritten)
741 {
742 hr = STG_E_MEDIUMFULL;
743 break;
744 }
745
746 if (bytesRead!=copySize)
747 cb.s.LowPart = 0;
748 else
749 cb.s.LowPart -= bytesRead;
750 }
751
752 /*
753 * Update number of bytes read and written
754 */
755 if (pcbRead)
756 {
757 pcbRead->s.LowPart = totalBytesRead.s.LowPart;
758 pcbRead->s.HighPart = totalBytesRead.s.HighPart;
759 }
760
761 if (pcbWritten)
762 {
763 pcbWritten->s.LowPart = totalBytesWritten.s.LowPart;
764 pcbWritten->s.HighPart = totalBytesWritten.s.HighPart;
765 }
766 return hr;
767}
768
769/***
770 * This method is part of the IStream interface.
771 *
772 * For streams contained in structured storages, this method
773 * does nothing. This is what the documentation tells us.
774 *
775 * See the documentation of IStream for more info.
776 */
777HRESULT WINAPI StgStreamImpl_Commit(
778 IStream* iface,
779 DWORD grfCommitFlags) /* [in] */
780{
781 return S_OK;
782}
783
784/***
785 * This method is part of the IStream interface.
786 *
787 * For streams contained in structured storages, this method
788 * does nothing. This is what the documentation tells us.
789 *
790 * See the documentation of IStream for more info.
791 */
792HRESULT WINAPI StgStreamImpl_Revert(
793 IStream* iface)
794{
795 return S_OK;
796}
797
798HRESULT WINAPI StgStreamImpl_LockRegion(
799 IStream* iface,
800 ULARGE_INTEGER libOffset, /* [in] */
801 ULARGE_INTEGER cb, /* [in] */
802 DWORD dwLockType) /* [in] */
803{
804 FIXME("not implemented!\n");
805 return E_NOTIMPL;
806}
807
808HRESULT WINAPI StgStreamImpl_UnlockRegion(
809 IStream* iface,
810 ULARGE_INTEGER libOffset, /* [in] */
811 ULARGE_INTEGER cb, /* [in] */
812 DWORD dwLockType) /* [in] */
813{
814 FIXME("not implemented!\n");
815 return E_NOTIMPL;
816}
817
818/***
819 * This method is part of the IStream interface.
820 *
821 * This method returns information about the current
822 * stream.
823 *
824 * See the documentation of IStream for more info.
825 */
826HRESULT WINAPI StgStreamImpl_Stat(
827 IStream* iface,
828 STATSTG* pstatstg, /* [out] */
829 DWORD grfStatFlag) /* [in] */
830{
831 StgStreamImpl* const This=(StgStreamImpl*)iface;
832
833 StgProperty curProperty;
834 BOOL readSucessful;
835
836 /*
837 * Read the information from the property.
838 */
839 readSucessful = StorageImpl_ReadProperty(This->parentStorage->ancestorStorage,
840 This->ownerProperty,
841 &curProperty);
842
843 if (readSucessful)
844 {
845 StorageUtl_CopyPropertyToSTATSTG(pstatstg,
846 &curProperty,
847 grfStatFlag);
848
849 pstatstg->grfMode = This->grfMode;
850
851 return S_OK;
852 }
853
854 return E_FAIL;
855}
856
857/***
858 * This method is part of the IStream interface.
859 *
860 * This method returns a clone of the interface that allows for
861 * another seek pointer
862 *
863 * See the documentation of IStream for more info.
864 *
865 * I am not totally sure what I am doing here but I presume that this
866 * should be basically as simple as creating a new stream with the same
867 * parent etc and positioning its seek cursor.
868 */
869HRESULT WINAPI StgStreamImpl_Clone(
870 IStream* iface,
871 IStream** ppstm) /* [out] */
872{
873 StgStreamImpl* const This=(StgStreamImpl*)iface;
874 HRESULT hres;
875 StgStreamImpl* new_stream;
876 LARGE_INTEGER seek_pos;
877
878 /*
879 * Sanity check
880 */
881 if ( ppstm == 0 )
882 return STG_E_INVALIDPOINTER;
883
884 new_stream = StgStreamImpl_Construct (This->parentStorage, This->grfMode, This->ownerProperty);
885
886 if (!new_stream)
887 return STG_E_INSUFFICIENTMEMORY; /* Currently the only reason for new_stream=0 */
888
889 *ppstm = (IStream*) new_stream;
890 seek_pos.QuadPart = This->currentPosition.QuadPart;
891
892 hres=StgStreamImpl_Seek (*ppstm, seek_pos, STREAM_SEEK_SET, NULL);
893
894 assert (SUCCEEDED(hres));
895
896 return S_OK;
897}
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