source: trunk/src/ole32/stg_stream.c@ 9738

Last change on this file since 9738 was 9400, 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 "winternl.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 * tell the caller what we calculated
569 */
570 This->currentPosition = *plibNewPosition;
571
572 return S_OK;
573}
574
575/***
576 * This method is part of the IStream interface.
577 *
578 * It will change the size of a stream.
579 *
580 * TODO: Switch from small blocks to big blocks and vice versa.
581 *
582 * See the documentation of IStream for more info.
583 */
584HRESULT WINAPI StgStreamImpl_SetSize(
585 IStream* iface,
586 ULARGE_INTEGER libNewSize) /* [in] */
587{
588 StgStreamImpl* const This=(StgStreamImpl*)iface;
589
590 StgProperty curProperty;
591 BOOL Success;
592
593 TRACE("(%p, %ld)\n", iface, libNewSize.s.LowPart);
594
595 /*
596 * As documented.
597 */
598 if (libNewSize.s.HighPart != 0)
599 return STG_E_INVALIDFUNCTION;
600
601 /*
602 * Do we have permission?
603 */
604 if (!(This->grfMode & (STGM_WRITE | STGM_READWRITE)))
605 return STG_E_ACCESSDENIED;
606
607 if (This->streamSize.s.LowPart == libNewSize.s.LowPart)
608 return S_OK;
609
610 /*
611 * This will happen if we're creating a stream
612 */
613 if ((This->smallBlockChain == 0) && (This->bigBlockChain == 0))
614 {
615 if (libNewSize.s.LowPart < LIMIT_TO_USE_SMALL_BLOCK)
616 {
617 This->smallBlockChain = SmallBlockChainStream_Construct(
618 This->parentStorage->ancestorStorage,
619 This->ownerProperty);
620 }
621 else
622 {
623 This->bigBlockChain = BlockChainStream_Construct(
624 This->parentStorage->ancestorStorage,
625 NULL,
626 This->ownerProperty);
627 }
628 }
629
630 /*
631 * Read this stream's property to see if it's small blocks or big blocks
632 */
633 Success = StorageImpl_ReadProperty(This->parentStorage->ancestorStorage,
634 This->ownerProperty,
635 &curProperty);
636 /*
637 * Determine if we have to switch from small to big blocks or vice versa
638 */
639 if ( (This->smallBlockChain!=0) &&
640 (curProperty.size.s.LowPart < LIMIT_TO_USE_SMALL_BLOCK) )
641 {
642 if (libNewSize.s.LowPart >= LIMIT_TO_USE_SMALL_BLOCK)
643 {
644 /*
645 * Transform the small block chain into a big block chain
646 */
647 This->bigBlockChain = Storage32Impl_SmallBlocksToBigBlocks(
648 This->parentStorage->ancestorStorage,
649 &This->smallBlockChain);
650 }
651 }
652
653 if (This->smallBlockChain!=0)
654 {
655 Success = SmallBlockChainStream_SetSize(This->smallBlockChain, libNewSize);
656 }
657 else
658 {
659 Success = BlockChainStream_SetSize(This->bigBlockChain, libNewSize);
660 }
661
662 /*
663 * Write the new information about this stream to the property
664 */
665 Success = StorageImpl_ReadProperty(This->parentStorage->ancestorStorage,
666 This->ownerProperty,
667 &curProperty);
668
669 curProperty.size.s.HighPart = libNewSize.s.HighPart;
670 curProperty.size.s.LowPart = libNewSize.s.LowPart;
671
672 if (Success)
673 {
674 StorageImpl_WriteProperty(This->parentStorage->ancestorStorage,
675 This->ownerProperty,
676 &curProperty);
677 }
678
679 This->streamSize = libNewSize;
680
681 return S_OK;
682}
683
684/***
685 * This method is part of the IStream interface.
686 *
687 * It will copy the 'cb' Bytes to 'pstm' IStream.
688 *
689 * See the documentation of IStream for more info.
690 */
691HRESULT WINAPI StgStreamImpl_CopyTo(
692 IStream* iface,
693 IStream* pstm, /* [unique][in] */
694 ULARGE_INTEGER cb, /* [in] */
695 ULARGE_INTEGER* pcbRead, /* [out] */
696 ULARGE_INTEGER* pcbWritten) /* [out] */
697{
698 HRESULT hr = S_OK;
699 BYTE tmpBuffer[128];
700 ULONG bytesRead, bytesWritten, copySize;
701 ULARGE_INTEGER totalBytesRead;
702 ULARGE_INTEGER totalBytesWritten;
703
704 TRACE("(%p, %p, %ld, %p, %p)\n",
705 iface, pstm, cb.s.LowPart, pcbRead, pcbWritten);
706
707 /*
708 * Sanity check
709 */
710 if ( pstm == 0 )
711 return STG_E_INVALIDPOINTER;
712
713 totalBytesRead.s.LowPart = totalBytesRead.s.HighPart = 0;
714 totalBytesWritten.s.LowPart = totalBytesWritten.s.HighPart = 0;
715
716 /*
717 * use stack to store data temporarily
718 * there is surely a more performant way of doing it, for now this basic
719 * implementation will do the job
720 */
721 while ( cb.s.LowPart > 0 )
722 {
723 if ( cb.s.LowPart >= 128 )
724 copySize = 128;
725 else
726 copySize = cb.s.LowPart;
727
728 IStream_Read(iface, tmpBuffer, copySize, &bytesRead);
729
730 totalBytesRead.s.LowPart += bytesRead;
731
732 IStream_Write(pstm, tmpBuffer, bytesRead, &bytesWritten);
733
734 totalBytesWritten.s.LowPart += bytesWritten;
735
736 /*
737 * Check that read & write operations were successful
738 */
739 if (bytesRead != bytesWritten)
740 {
741 hr = STG_E_MEDIUMFULL;
742 break;
743 }
744
745 if (bytesRead!=copySize)
746 cb.s.LowPart = 0;
747 else
748 cb.s.LowPart -= bytesRead;
749 }
750
751 /*
752 * Update number of bytes read and written
753 */
754 if (pcbRead)
755 {
756 pcbRead->s.LowPart = totalBytesRead.s.LowPart;
757 pcbRead->s.HighPart = totalBytesRead.s.HighPart;
758 }
759
760 if (pcbWritten)
761 {
762 pcbWritten->s.LowPart = totalBytesWritten.s.LowPart;
763 pcbWritten->s.HighPart = totalBytesWritten.s.HighPart;
764 }
765 return hr;
766}
767
768/***
769 * This method is part of the IStream interface.
770 *
771 * For streams contained in structured storages, this method
772 * does nothing. This is what the documentation tells us.
773 *
774 * See the documentation of IStream for more info.
775 */
776HRESULT WINAPI StgStreamImpl_Commit(
777 IStream* iface,
778 DWORD grfCommitFlags) /* [in] */
779{
780 return S_OK;
781}
782
783/***
784 * This method is part of the IStream interface.
785 *
786 * For streams contained in structured storages, this method
787 * does nothing. This is what the documentation tells us.
788 *
789 * See the documentation of IStream for more info.
790 */
791HRESULT WINAPI StgStreamImpl_Revert(
792 IStream* iface)
793{
794 return S_OK;
795}
796
797HRESULT WINAPI StgStreamImpl_LockRegion(
798 IStream* iface,
799 ULARGE_INTEGER libOffset, /* [in] */
800 ULARGE_INTEGER cb, /* [in] */
801 DWORD dwLockType) /* [in] */
802{
803 FIXME("not implemented!\n");
804 return E_NOTIMPL;
805}
806
807HRESULT WINAPI StgStreamImpl_UnlockRegion(
808 IStream* iface,
809 ULARGE_INTEGER libOffset, /* [in] */
810 ULARGE_INTEGER cb, /* [in] */
811 DWORD dwLockType) /* [in] */
812{
813 FIXME("not implemented!\n");
814 return E_NOTIMPL;
815}
816
817/***
818 * This method is part of the IStream interface.
819 *
820 * This method returns information about the current
821 * stream.
822 *
823 * See the documentation of IStream for more info.
824 */
825HRESULT WINAPI StgStreamImpl_Stat(
826 IStream* iface,
827 STATSTG* pstatstg, /* [out] */
828 DWORD grfStatFlag) /* [in] */
829{
830 StgStreamImpl* const This=(StgStreamImpl*)iface;
831
832 StgProperty curProperty;
833 BOOL readSucessful;
834
835 /*
836 * Read the information from the property.
837 */
838 readSucessful = StorageImpl_ReadProperty(This->parentStorage->ancestorStorage,
839 This->ownerProperty,
840 &curProperty);
841
842 if (readSucessful)
843 {
844 StorageUtl_CopyPropertyToSTATSTG(pstatstg,
845 &curProperty,
846 grfStatFlag);
847
848 pstatstg->grfMode = This->grfMode;
849
850 return S_OK;
851 }
852
853 return E_FAIL;
854}
855
856/***
857 * This method is part of the IStream interface.
858 *
859 * This method returns a clone of the interface that allows for
860 * another seek pointer
861 *
862 * See the documentation of IStream for more info.
863 *
864 * I am not totally sure what I am doing here but I presume that this
865 * should be basically as simple as creating a new stream with the same
866 * parent etc and positioning its seek cursor.
867 */
868HRESULT WINAPI StgStreamImpl_Clone(
869 IStream* iface,
870 IStream** ppstm) /* [out] */
871{
872 StgStreamImpl* const This=(StgStreamImpl*)iface;
873 HRESULT hres;
874 StgStreamImpl* new_stream;
875 LARGE_INTEGER seek_pos;
876
877 /*
878 * Sanity check
879 */
880 if ( ppstm == 0 )
881 return STG_E_INVALIDPOINTER;
882
883 new_stream = StgStreamImpl_Construct (This->parentStorage, This->grfMode, This->ownerProperty);
884
885 if (!new_stream)
886 return STG_E_INSUFFICIENTMEMORY; /* Currently the only reason for new_stream=0 */
887
888 *ppstm = (IStream*) new_stream;
889 seek_pos.QuadPart = This->currentPosition.QuadPart;
890
891 hres=StgStreamImpl_Seek (*ppstm, seek_pos, STREAM_SEEK_SET, NULL);
892
893 assert (SUCCEEDED(hres));
894
895 return S_OK;
896}
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