VDVfs.cpp@ 72293

Last change on this file since 72293 was 70307, checked in by vboxsync, 7 years ago
VDVfs.cpp: Nit.
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1	/* $Id: VDVfs.cpp 70307 2017-12-22 08:37:01Z vboxsync $ */
2	/** @file
3	* Virtual Disk Container implementation. - VFS glue.
4	*/
5
6	/*
7	* Copyright (C) 2012-2017 Oracle Corporation
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*/
17
18
19	/*********************************************************************************************************************************
20	* Header Files *
21	*********************************************************************************************************************************/
22	#include <iprt/types.h>
23	#include <iprt/assert.h>
24	#include <iprt/mem.h>
25	#include <iprt/err.h>
26	#include <iprt/asm.h>
27	#include <iprt/string.h>
28	#include <iprt/file.h>
29	#include <iprt/sg.h>
30	#include <iprt/vfslowlevel.h>
31	#include <iprt/poll.h>
32	#include <VBox/vd.h>
33
34
35	/*********************************************************************************************************************************
36	* Structures and Typedefs *
37	*********************************************************************************************************************************/
38
39	/**
40	* The internal data of a DVM volume I/O stream.
41	*/
42	typedef struct VDVFSFILE
43	{
44	/** The volume the VFS file belongs to. */
45	PVDISK pDisk;
46	/** Current position. */
47	uint64_t offCurPos;
48	/** Flags given during creation. */
49	uint32_t fFlags;
50	} VDVFSFILE;
51	/** Pointer to a the internal data of a DVM volume file. */
52	typedef VDVFSFILE *PVDVFSFILE;
53
54	/**
55	* VD read helper taking care of unaligned accesses.
56	*
57	* @return VBox status code.
58	* @param pDisk VD disk container.
59	* @param off Offset to start reading from.
60	* @param pvBuf Pointer to the buffer to read into.
61	* @param cbRead Amount of bytes to read.
62	*/
63	static int vdReadHelper(PVDISK pDisk, uint64_t off, void *pvBuf, size_t cbRead)
64	{
65	int rc;
66
67	/* Take direct route if the request is sector aligned. */
68	uint64_t const offMisalign = off & 511;
69	size_t const cbMisalign = (off + cbRead) & 511;
70	if ( !offMisalign
71	&& !cbMisalign)
72	rc = VDRead(pDisk, off, pvBuf, cbRead);
73	else
74	{
75	uint8_t pbBuf = (uint8_t )pvBuf;
76	uint8_t abBuf[512];
77
78	/* Unaligned buffered read of head. Aligns the offset. */
79	if (offMisalign)
80	{
81	rc = VDRead(pDisk, off - offMisalign, abBuf, 512);
82	if (RT_SUCCESS(rc))
83	{
84	size_t const cbPart = RT_MIN(512 - offMisalign, cbRead);
85	memcpy(pbBuf, &abBuf[offMisalign], cbPart);
86	pbBuf += cbPart;
87	off += cbPart;
88	cbRead -= cbPart;
89	}
90	}
91	else
92	rc = VINF_SUCCESS;
93
94	/* Aligned direct read. */
95	if ( RT_SUCCESS(rc)
96	&& cbRead >= 512)
97	{
98	Assert(!(off % 512));
99
100	size_t cbPart = cbRead - cbMisalign;
101	Assert(!(cbPart % 512));
102	rc = VDRead(pDisk, off, pbBuf, cbPart);
103	if (RT_SUCCESS(rc))
104	{
105	pbBuf += cbPart;
106	off += cbPart;
107	cbRead -= cbPart;
108	}
109	}
110
111	/* Unaligned buffered read of tail. */
112	if ( RT_SUCCESS(rc)
113	&& cbRead)
114	{
115	Assert(cbRead == cbMisalign);
116	Assert(cbRead < 512);
117	Assert(!(off % 512));
118
119	rc = VDRead(pDisk, off, abBuf, 512);
120	if (RT_SUCCESS(rc))
121	memcpy(pbBuf, abBuf, cbRead);
122	}
123	}
124
125	return rc;
126	}
127
128
129	/**
130	* VD write helper taking care of unaligned accesses.
131	*
132	* @return VBox status code.
133	* @param pDisk VD disk container.
134	* @param off Offset to start writing to.
135	* @param pvBuf Pointer to the buffer to read from.
136	* @param cbWrite Amount of bytes to write.
137	*/
138	static int vdWriteHelper(PVDISK pDisk, uint64_t off, const void *pvBuf, size_t cbWrite)
139	{
140	int rc;
141
142	/* Take direct route if the request is sector aligned. */
143	uint64_t const offMisalign = off & 511;
144	size_t const cbMisalign = (off + cbWrite) & 511;
145	if ( !offMisalign
146	&& !cbMisalign)
147	rc = VDWrite(pDisk, off, pvBuf, cbWrite);
148	else
149	{
150	uint8_t pbBuf = (uint8_t )pvBuf;
151	uint8_t abBuf[512];
152
153	/* Unaligned buffered read+write of head. Aligns the offset. */
154	if (offMisalign)
155	{
156	rc = VDRead(pDisk, off - offMisalign, abBuf, 512);
157	if (RT_SUCCESS(rc))
158	{
159	size_t const cbPart = RT_MIN(512 - offMisalign, cbWrite);
160	memcpy(&abBuf[offMisalign], pbBuf, cbPart);
161	rc = VDWrite(pDisk, off - offMisalign, abBuf, 512);
162	if (RT_SUCCESS(rc))
163	{
164	pbBuf += cbPart;
165	off += cbPart;
166	cbWrite -= cbPart;
167	}
168	}
169	}
170	else
171	rc = VINF_SUCCESS;
172
173	/* Aligned direct write. */
174	if ( RT_SUCCESS(rc)
175	&& cbWrite >= 512)
176	{
177	Assert(!(off % 512));
178
179	size_t cbPart = cbWrite - cbMisalign;
180	Assert(!(cbPart % 512));
181	rc = VDWrite(pDisk, off, pbBuf, cbPart);
182	if (RT_SUCCESS(rc))
183	{
184	pbBuf += cbPart;
185	off += cbPart;
186	cbWrite -= cbPart;
187	}
188	}
189
190	/* Unaligned buffered read+write of tail. */
191	if ( RT_SUCCESS(rc)
192	&& cbWrite > 0)
193	{
194	Assert(cbWrite == cbMisalign);
195	Assert(cbWrite < 512);
196	Assert(!(off % 512));
197
198	rc = VDRead(pDisk, off, abBuf, 512);
199	if (RT_SUCCESS(rc))
200	{
201	memcpy(abBuf, pbBuf, cbWrite);
202	rc = VDWrite(pDisk, off, abBuf, 512);
203	}
204	}
205	}
206
207	return rc;
208	}
209
210
211	/**
212	* @interface_method_impl{RTVFSOBJOPS,pfnClose}
213	*/
214	static DECLCALLBACK(int) vdVfsFile_Close(void *pvThis)
215	{
216	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
217
218	if (pThis->fFlags & VD_VFSFILE_DESTROY_ON_RELEASE)
219	VDDestroy(pThis->pDisk);
220
221	return VINF_SUCCESS;
222	}
223
224
225	/**
226	* @interface_method_impl{RTVFSOBJOPS,pfnQueryInfo}
227	*/
228	static DECLCALLBACK(int) vdVfsFile_QueryInfo(void *pvThis, PRTFSOBJINFO pObjInfo, RTFSOBJATTRADD enmAddAttr)
229	{
230	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
231	unsigned const cOpenImages = VDGetCount(pThis->pDisk);
232
233	pObjInfo->cbObject = VDGetSize(pThis->pDisk, cOpenImages - 1);
234	pObjInfo->cbAllocated = 0;
235	for (unsigned iImage = 0; iImage < cOpenImages; iImage++)
236	pObjInfo->cbAllocated += VDGetFileSize(pThis->pDisk, iImage);
237
238	/** @todo enumerate the disk images directly... */
239	RTTimeNow(&pObjInfo->AccessTime);
240	pObjInfo->BirthTime = pObjInfo->AccessTime;
241	pObjInfo->ChangeTime = pObjInfo->AccessTime;
242	pObjInfo->ModificationTime = pObjInfo->AccessTime;
243
244	pObjInfo->Attr.fMode = RTFS_DOS_NT_NORMAL \| RTFS_TYPE_FILE \| 0644;
245	pObjInfo->Attr.enmAdditional = enmAddAttr;
246	switch (enmAddAttr)
247	{
248	case RTFSOBJATTRADD_UNIX:
249	pObjInfo->Attr.u.Unix.uid = NIL_RTUID;
250	pObjInfo->Attr.u.Unix.gid = NIL_RTGID;
251	pObjInfo->Attr.u.Unix.cHardlinks = 1;
252	pObjInfo->Attr.u.Unix.INodeIdDevice = 0;
253	pObjInfo->Attr.u.Unix.INodeId = 0;
254	pObjInfo->Attr.u.Unix.fFlags = 0;
255	pObjInfo->Attr.u.Unix.GenerationId = 0;
256	pObjInfo->Attr.u.Unix.Device = 0;
257	break;
258
259	case RTFSOBJATTRADD_UNIX_OWNER:
260	pObjInfo->Attr.u.UnixOwner.uid = NIL_RTUID;
261	pObjInfo->Attr.u.UnixOwner.szName[0] = '\0';
262	break;
263	case RTFSOBJATTRADD_UNIX_GROUP:
264	pObjInfo->Attr.u.UnixGroup.gid = NIL_RTGID;
265	pObjInfo->Attr.u.UnixGroup.szName[0] = '\0';
266	break;
267	case RTFSOBJATTRADD_EASIZE:
268	pObjInfo->Attr.u.EASize.cb = 0;
269	break;
270
271	default:
272	AssertFailedReturn(VERR_INVALID_PARAMETER);
273	}
274
275	return VINF_SUCCESS;
276	}
277
278
279	/**
280	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnRead}
281	*/
282	static DECLCALLBACK(int) vdVfsFile_Read(void pvThis, RTFOFF off, PCRTSGBUF pSgBuf, bool fBlocking, size_t pcbRead)
283	{
284	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
285
286	Assert(pSgBuf->cSegs == 1);
287	NOREF(fBlocking);
288
289	/*
290	* Find the current position and check if it's within the volume.
291	*/
292	uint64_t offUnsigned = off < 0 ? pThis->offCurPos : (uint64_t)off;
293	uint64_t const cbImage = VDGetSize(pThis->pDisk, VD_LAST_IMAGE);
294	if (offUnsigned >= cbImage)
295	{
296	if (pcbRead)
297	{
298	*pcbRead = 0;
299	pThis->offCurPos = cbImage;
300	return VINF_EOF;
301	}
302	return VERR_EOF;
303	}
304
305	int rc = VINF_SUCCESS;
306	size_t cbLeftToRead = pSgBuf->paSegs[0].cbSeg;
307	if (offUnsigned + cbLeftToRead <= cbImage)
308	{
309	if (pcbRead)
310	*pcbRead = cbLeftToRead;
311	}
312	else
313	{
314	if (!pcbRead)
315	return VERR_EOF;
316	*pcbRead = cbLeftToRead = (size_t)(cbImage - offUnsigned);
317	rc = VINF_EOF;
318	}
319
320	/*
321	* Ok, we've got a valid stretch within the file. Do the reading.
322	*/
323	if (cbLeftToRead > 0)
324	{
325	int rc2 = vdReadHelper(pThis->pDisk, offUnsigned, pSgBuf->paSegs[0].pvSeg, cbLeftToRead);
326	if (RT_SUCCESS(rc2))
327	offUnsigned += cbLeftToRead;
328	else
329	rc = rc2;
330	}
331
332	pThis->offCurPos = offUnsigned;
333	return rc;
334	}
335
336
337	/**
338	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnWrite}
339	*/
340	static DECLCALLBACK(int) vdVfsFile_Write(void pvThis, RTFOFF off, PCRTSGBUF pSgBuf, bool fBlocking, size_t pcbWritten)
341	{
342	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
343
344	Assert(pSgBuf->cSegs == 1);
345	NOREF(fBlocking);
346
347	/*
348	* Find the current position and check if it's within the volume.
349	* Writing beyond the end of a volume is not supported.
350	*/
351	uint64_t offUnsigned = off < 0 ? pThis->offCurPos : (uint64_t)off;
352	uint64_t const cbImage = VDGetSize(pThis->pDisk, VD_LAST_IMAGE);
353	if (offUnsigned >= cbImage)
354	{
355	if (pcbWritten)
356	{
357	*pcbWritten = 0;
358	pThis->offCurPos = cbImage;
359	}
360	return VERR_EOF;
361	}
362
363	size_t cbLeftToWrite;
364	if (offUnsigned + pSgBuf->paSegs[0].cbSeg < cbImage)
365	{
366	cbLeftToWrite = pSgBuf->paSegs[0].cbSeg;
367	if (pcbWritten)
368	*pcbWritten = cbLeftToWrite;
369	}
370	else
371	{
372	if (!pcbWritten)
373	return VERR_EOF;
374	*pcbWritten = cbLeftToWrite = (size_t)(cbImage - offUnsigned);
375	}
376
377	/*
378	* Ok, we've got a valid stretch within the file. Do the reading.
379	*/
380	int rc = VINF_SUCCESS;
381	if (cbLeftToWrite > 0)
382	{
383	rc = vdWriteHelper(pThis->pDisk, offUnsigned, pSgBuf->paSegs[0].pvSeg, cbLeftToWrite);
384	if (RT_SUCCESS(rc))
385	offUnsigned += cbLeftToWrite;
386	}
387
388	pThis->offCurPos = offUnsigned;
389	return rc;
390	}
391
392
393	/**
394	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnFlush}
395	*/
396	static DECLCALLBACK(int) vdVfsFile_Flush(void *pvThis)
397	{
398	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
399	return VDFlush(pThis->pDisk);
400	}
401
402
403	/**
404	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnTell}
405	*/
406	static DECLCALLBACK(int) vdVfsFile_Tell(void *pvThis, PRTFOFF poffActual)
407	{
408	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
409	*poffActual = pThis->offCurPos;
410	return VINF_SUCCESS;
411	}
412
413
414	/**
415	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetMode}
416	*/
417	static DECLCALLBACK(int) vdVfsFile_SetMode(void *pvThis, RTFMODE fMode, RTFMODE fMask)
418	{
419	NOREF(pvThis);
420	NOREF(fMode);
421	NOREF(fMask);
422	return VERR_NOT_SUPPORTED;
423	}
424
425
426	/**
427	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetTimes}
428	*/
429	static DECLCALLBACK(int) vdVfsFile_SetTimes(void *pvThis, PCRTTIMESPEC pAccessTime, PCRTTIMESPEC pModificationTime,
430	PCRTTIMESPEC pChangeTime, PCRTTIMESPEC pBirthTime)
431	{
432	NOREF(pvThis);
433	NOREF(pAccessTime);
434	NOREF(pModificationTime);
435	NOREF(pChangeTime);
436	NOREF(pBirthTime);
437	return VERR_NOT_SUPPORTED;
438	}
439
440
441	/**
442	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetOwner}
443	*/
444	static DECLCALLBACK(int) vdVfsFile_SetOwner(void *pvThis, RTUID uid, RTGID gid)
445	{
446	NOREF(pvThis);
447	NOREF(uid);
448	NOREF(gid);
449	return VERR_NOT_SUPPORTED;
450	}
451
452
453	/**
454	* @interface_method_impl{RTVFSFILEOPS,pfnSeek}
455	*/
456	static DECLCALLBACK(int) vdVfsFile_Seek(void *pvThis, RTFOFF offSeek, unsigned uMethod, PRTFOFF poffActual)
457	{
458	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
459
460	/*
461	* Seek relative to which position.
462	*/
463	uint64_t offWrt;
464	switch (uMethod)
465	{
466	case RTFILE_SEEK_BEGIN:
467	offWrt = 0;
468	break;
469
470	case RTFILE_SEEK_CURRENT:
471	offWrt = pThis->offCurPos;
472	break;
473
474	case RTFILE_SEEK_END:
475	offWrt = VDGetSize(pThis->pDisk, VD_LAST_IMAGE);
476	break;
477
478	default:
479	return VERR_INTERNAL_ERROR_5;
480	}
481
482	/*
483	* Calc new position, take care to stay without bounds.
484	*/
485	uint64_t offNew;
486	if (offSeek == 0)
487	offNew = offWrt;
488	else if (offSeek > 0)
489	{
490	offNew = offWrt + offSeek;
491	if ( offNew < offWrt
492	\|\| offNew > RTFOFF_MAX)
493	offNew = RTFOFF_MAX;
494	}
495	else if ((uint64_t)-offSeek < offWrt)
496	offNew = offWrt + offSeek;
497	else
498	offNew = 0;
499
500	/*
501	* Update the state and set return value.
502	*/
503	pThis->offCurPos = offNew;
504
505	*poffActual = offNew;
506	return VINF_SUCCESS;
507	}
508
509
510	/**
511	* @interface_method_impl{RTVFSFILEOPS,pfnQuerySize}
512	*/
513	static DECLCALLBACK(int) vdVfsFile_QuerySize(void pvThis, uint64_t pcbFile)
514	{
515	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
516	*pcbFile = VDGetSize(pThis->pDisk, VD_LAST_IMAGE);
517	return VINF_SUCCESS;
518	}
519
520
521	/**
522	* Standard file operations.
523	*/
524	DECL_HIDDEN_CONST(const RTVFSFILEOPS) g_vdVfsStdFileOps =
525	{
526	{ /* Stream */
527	{ /* Obj */
528	RTVFSOBJOPS_VERSION,
529	RTVFSOBJTYPE_FILE,
530	"VDFile",
531	vdVfsFile_Close,
532	vdVfsFile_QueryInfo,
533	RTVFSOBJOPS_VERSION
534	},
535	RTVFSIOSTREAMOPS_VERSION,
536	RTVFSIOSTREAMOPS_FEAT_NO_SG,
537	vdVfsFile_Read,
538	vdVfsFile_Write,
539	vdVfsFile_Flush,
540	NULL /PollOne/,
541	vdVfsFile_Tell,
542	NULL /Skip/,
543	NULL /ZeroFill/,
544	RTVFSIOSTREAMOPS_VERSION,
545	},
546	RTVFSFILEOPS_VERSION,
547	/RTVFSIOFILEOPS_FEAT_NO_AT_OFFSET/ 0,
548	{ /* ObjSet */
549	RTVFSOBJSETOPS_VERSION,
550	RT_OFFSETOF(RTVFSFILEOPS, Stream.Obj) - RT_OFFSETOF(RTVFSFILEOPS, ObjSet),
551	vdVfsFile_SetMode,
552	vdVfsFile_SetTimes,
553	vdVfsFile_SetOwner,
554	RTVFSOBJSETOPS_VERSION
555	},
556	vdVfsFile_Seek,
557	vdVfsFile_QuerySize,
558	NULL /SetSize/,
559	NULL /QueryMaxSize/,
560	RTVFSFILEOPS_VERSION
561	};
562
563
564	VBOXDDU_DECL(int) VDCreateVfsFileFromDisk(PVDISK pDisk, uint32_t fFlags,
565	PRTVFSFILE phVfsFile)
566	{
567	AssertPtrReturn(pDisk, VERR_INVALID_HANDLE);
568	AssertPtrReturn(phVfsFile, VERR_INVALID_POINTER);
569	AssertReturn((fFlags & ~VD_VFSFILE_FLAGS_MASK) == 0, VERR_INVALID_PARAMETER);
570
571	/*
572	* Create the volume file.
573	*/
574	RTVFSFILE hVfsFile;
575	PVDVFSFILE pThis;
576	int rc = RTVfsNewFile(&g_vdVfsStdFileOps, sizeof(*pThis), RTFILE_O_OPEN \| RTFILE_O_READ \| RTFILE_O_WRITE,
577	NIL_RTVFS, NIL_RTVFSLOCK, &hVfsFile, (void **)&pThis);
578	if (RT_SUCCESS(rc))
579	{
580	pThis->offCurPos = 0;
581	pThis->pDisk = pDisk;
582	pThis->fFlags = fFlags;
583
584	*phVfsFile = hVfsFile;
585	return VINF_SUCCESS;
586	}
587
588	return rc;
589	}
590
591
592	/**
593	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnValidate}
594	*/
595	static DECLCALLBACK(int) vdVfsChain_Validate(PCRTVFSCHAINELEMENTREG pProviderReg, PRTVFSCHAINSPEC pSpec,
596	PRTVFSCHAINELEMSPEC pElement, uint32_t *poffError, PRTERRINFO pErrInfo)
597	{
598	RT_NOREF(pProviderReg, pSpec);
599
600	/*
601	* Basic checks.
602	*/
603	if (pElement->enmTypeIn != RTVFSOBJTYPE_INVALID)
604	return VERR_VFS_CHAIN_MUST_BE_FIRST_ELEMENT;
605	if ( pElement->enmType != RTVFSOBJTYPE_FILE
606	&& pElement->enmType != RTVFSOBJTYPE_IO_STREAM)
607	return VERR_VFS_CHAIN_ONLY_FILE_OR_IOS;
608
609	if (pElement->cArgs < 1)
610	return VERR_VFS_CHAIN_AT_LEAST_ONE_ARG;
611
612	/*
613	* Parse the flag if present, save in pElement->uProvider.
614	*/
615	uint32_t fFlags = (pSpec->fOpenFile & RTFILE_O_ACCESS_MASK) == RTFILE_O_READ
616	? VD_OPEN_FLAGS_READONLY : VD_OPEN_FLAGS_NORMAL;
617	if (pElement->cArgs > 1)
618	{
619	pElement->paArgs[pElement->cArgs - 1].uProvider = true; /* indicates flags */
620	const char *psz = pElement->paArgs[pElement->cArgs - 1].psz;
621	if (*psz)
622	{
623	if ( !strcmp(psz, "ro")
624	\|\| !strcmp(psz, "r"))
625	{
626	fFlags &= ~(VD_OPEN_FLAGS_READONLY \| VD_OPEN_FLAGS_NORMAL);
627	fFlags \|= VD_OPEN_FLAGS_READONLY;
628	}
629	else if (!strcmp(psz, "rw"))
630	{
631	fFlags &= ~(VD_OPEN_FLAGS_READONLY \| VD_OPEN_FLAGS_NORMAL);
632	fFlags \|= VD_OPEN_FLAGS_NORMAL;
633	}
634	else if (strlen(psz) <= 4)
635	{
636	*poffError = pElement->paArgs[pElement->cArgs - 1].offSpec;
637	return RTErrInfoSet(pErrInfo, VERR_VFS_CHAIN_INVALID_ARGUMENT, "Expected 'ro' or 'rw' as argument");
638	}
639	else
640	pElement->paArgs[pElement->cArgs - 1].uProvider = false; /* indicates no flags */
641	}
642	}
643
644	pElement->uProvider = fFlags;
645	if ( pElement->cArgs > 2
646	\|\| (pElement->cArgs == 2 && !pElement->paArgs[pElement->cArgs - 1].uProvider))
647	pElement->uProvider \|= RT_BIT_64(63);
648	return VINF_SUCCESS;
649	}
650
651
652	/**
653	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnInstantiate}
654	*/
655	static DECLCALLBACK(int) vdVfsChain_Instantiate(PCRTVFSCHAINELEMENTREG pProviderReg, PCRTVFSCHAINSPEC pSpec,
656	PCRTVFSCHAINELEMSPEC pElement, RTVFSOBJ hPrevVfsObj,
657	PRTVFSOBJ phVfsObj, uint32_t *poffError, PRTERRINFO pErrInfo)
658	{
659	RT_NOREF(pProviderReg, pSpec, poffError, pErrInfo);
660	AssertReturn(hPrevVfsObj == NIL_RTVFSOBJ, VERR_VFS_CHAIN_IPE);
661
662	/* Determin the format. */
663	char *pszFormat = NULL;
664	VDTYPE enmType = VDTYPE_INVALID;
665	int rc = VDGetFormat(NULL, NULL, pElement->paArgs[0].psz, &pszFormat, &enmType);
666	if (RT_SUCCESS(rc))
667	{
668	PVDISK pDisk = NULL;
669	rc = VDCreate(NULL, enmType, &pDisk);
670	if (RT_SUCCESS(rc))
671	{
672	if (!(pElement->uProvider & RT_BIT_64(63)))
673	rc = VDOpen(pDisk, pszFormat, pElement->paArgs[0].psz, (uint32_t)pElement->uProvider, NULL);
674	else
675	{
676	uint32_t cChain = pElement->cArgs;
677	if (pElement->cArgs == 2 && pElement->paArgs[pElement->cArgs - 1].uProvider != 0)
678	cChain--;
679	uint32_t const fFinal = (uint32_t)pElement->uProvider;
680	uint32_t const fReadOnly = (fFinal & ~(VD_OPEN_FLAGS_READONLY \| VD_OPEN_FLAGS_NORMAL)) \| VD_OPEN_FLAGS_READONLY;
681	uint32_t iChain;
682	for (iChain = 0; iChain < cChain && RT_SUCCESS(rc); iChain++)
683	rc = VDOpen(pDisk, pszFormat, pElement->paArgs[iChain].psz, iChain + 1 >= cChain ? fFinal : fReadOnly, NULL);
684	}
685	if (RT_SUCCESS(rc))
686	{
687	RTVFSFILE hVfsFile;
688	rc = VDCreateVfsFileFromDisk(pDisk, VD_VFSFILE_DESTROY_ON_RELEASE, &hVfsFile);
689	if (RT_SUCCESS(rc))
690	{
691	RTStrFree(pszFormat);
692
693	*phVfsObj = RTVfsObjFromFile(hVfsFile);
694	RTVfsFileRelease(hVfsFile);
695
696	if (*phVfsObj != NIL_RTVFSOBJ)
697	return VINF_SUCCESS;
698	return VERR_VFS_CHAIN_CAST_FAILED;
699	}
700	}
701	VDDestroy(pDisk);
702	}
703	RTStrFree(pszFormat);
704	}
705	return rc;
706	}
707
708
709	/**
710	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnCanReuseElement}
711	*/
712	static DECLCALLBACK(bool) vdVfsChain_CanReuseElement(PCRTVFSCHAINELEMENTREG pProviderReg,
713	PCRTVFSCHAINSPEC pSpec, PCRTVFSCHAINELEMSPEC pElement,
714	PCRTVFSCHAINSPEC pReuseSpec, PCRTVFSCHAINELEMSPEC pReuseElement)
715	{
716	RT_NOREF(pProviderReg, pSpec, pElement, pReuseSpec, pReuseElement);
717	return false;
718	}
719
720
721	/** VFS chain element 'file'. */
722	static RTVFSCHAINELEMENTREG g_rtVfsChainIsoFsVolReg =
723	{
724	/* uVersion = */ RTVFSCHAINELEMENTREG_VERSION,
725	/* fReserved = */ 0,
726	/* pszName = */ "vd",
727	/* ListEntry = */ { NULL, NULL },
728	/* pszHelp = */ "Opens a container image using the VD API.\n"
729	"To open a snapshot chain, start with the root image and end with the more recent diff image.\n"
730	"The final argument can be a flag 'ro' or 'r' for read-only, 'rw' for read-write.",
731	/* pfnValidate = */ vdVfsChain_Validate,
732	/* pfnInstantiate = */ vdVfsChain_Instantiate,
733	/* pfnCanReuseElement = */ vdVfsChain_CanReuseElement,
734	/* uEndMarker = */ RTVFSCHAINELEMENTREG_VERSION
735	};
736
737	RTVFSCHAIN_AUTO_REGISTER_ELEMENT_PROVIDER(&g_rtVfsChainIsoFsVolReg, rtVfsChainIsoFsVolReg);
738

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source: vbox/trunk/src/VBox/Storage/VDVfs.cpp@ 72293

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