VDVfs.cpp@ 76389

Last change on this file since 76389 was 74355, checked in by vboxsync, 6 years ago
Storage/VDVfs: Double buffer writes when write filters are present.
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File size: 23.5 KB

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1	/* $Id: VDVfs.cpp 74355 2018-09-18 21:54:56Z 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	#include "VDInternal.h"
35
36
37	/*********************************************************************************************************************************
38	* Structures and Typedefs *
39	*********************************************************************************************************************************/
40
41	/**
42	* The internal data of a DVM volume I/O stream.
43	*/
44	typedef struct VDVFSFILE
45	{
46	/** The volume the VFS file belongs to. */
47	PVDISK pDisk;
48	/** Current position. */
49	uint64_t offCurPos;
50	/** Flags given during creation. */
51	uint32_t fFlags;
52	} VDVFSFILE;
53	/** Pointer to a the internal data of a DVM volume file. */
54	typedef VDVFSFILE *PVDVFSFILE;
55
56	/**
57	* VD read helper taking care of unaligned accesses.
58	*
59	* @return VBox status code.
60	* @param pDisk VD disk container.
61	* @param off Offset to start reading from.
62	* @param pvBuf Pointer to the buffer to read into.
63	* @param cbRead Amount of bytes to read.
64	*/
65	static int vdReadHelper(PVDISK pDisk, uint64_t off, void *pvBuf, size_t cbRead)
66	{
67	int rc;
68
69	/* Take direct route if the request is sector aligned. */
70	uint64_t const offMisalign = off & 511;
71	size_t const cbMisalign = (off + cbRead) & 511;
72	if ( !offMisalign
73	&& !cbMisalign)
74	rc = VDRead(pDisk, off, pvBuf, cbRead);
75	else
76	{
77	uint8_t pbBuf = (uint8_t )pvBuf;
78	uint8_t abBuf[512];
79
80	/* Unaligned buffered read of head. Aligns the offset. */
81	if (offMisalign)
82	{
83	rc = VDRead(pDisk, off - offMisalign, abBuf, 512);
84	if (RT_SUCCESS(rc))
85	{
86	size_t const cbPart = RT_MIN(512 - offMisalign, cbRead);
87	memcpy(pbBuf, &abBuf[offMisalign], cbPart);
88	pbBuf += cbPart;
89	off += cbPart;
90	cbRead -= cbPart;
91	}
92	}
93	else
94	rc = VINF_SUCCESS;
95
96	/* Aligned direct read. */
97	if ( RT_SUCCESS(rc)
98	&& cbRead >= 512)
99	{
100	Assert(!(off % 512));
101
102	size_t cbPart = cbRead - cbMisalign;
103	Assert(!(cbPart % 512));
104	rc = VDRead(pDisk, off, pbBuf, cbPart);
105	if (RT_SUCCESS(rc))
106	{
107	pbBuf += cbPart;
108	off += cbPart;
109	cbRead -= cbPart;
110	}
111	}
112
113	/* Unaligned buffered read of tail. */
114	if ( RT_SUCCESS(rc)
115	&& cbRead)
116	{
117	Assert(cbRead == cbMisalign);
118	Assert(cbRead < 512);
119	Assert(!(off % 512));
120
121	rc = VDRead(pDisk, off, abBuf, 512);
122	if (RT_SUCCESS(rc))
123	memcpy(pbBuf, abBuf, cbRead);
124	}
125	}
126
127	return rc;
128	}
129
130
131	/**
132	* VD write helper taking care of unaligned accesses.
133	*
134	* @return VBox status code.
135	* @param pDisk VD disk container.
136	* @param off Offset to start writing to.
137	* @param pvSrc Pointer to the buffer to read from.
138	* @param cbWrite Amount of bytes to write.
139	*/
140	static int vdWriteHelper(PVDISK pDisk, uint64_t off, const void *pvSrc, size_t cbWrite)
141	{
142	uint8_t const pbSrc = (uint8_t const )pvSrc;
143	uint8_t abBuf[4096];
144	int rc;
145
146	/*
147	* Take direct route if the request is sector aligned.
148	*/
149	uint64_t const offMisalign = off & 511;
150	size_t const cbMisalign = (off + cbWrite) & 511;
151	if ( !offMisalign
152	&& !cbMisalign)
153	{
154	if (RTListIsEmpty(&pDisk->ListFilterChainWrite))
155	rc = VDWrite(pDisk, off, pbSrc, cbWrite);
156	else
157	{
158	/* Filtered writes must be double buffered as the filter may need to modify the input buffer directly. */
159	do
160	{
161	size_t cbThisWrite = RT_MIN(cbWrite, sizeof(abBuf));
162	rc = VDWrite(pDisk, off, memcpy(abBuf, pbSrc, cbThisWrite), cbThisWrite);
163	if (RT_SUCCESS(rc))
164	{
165	pbSrc += cbThisWrite;
166	off += cbThisWrite;
167	cbWrite -= cbThisWrite;
168	}
169	else
170	break;
171	} while (cbWrite > 0);
172	}
173	}
174	else
175	{
176
177	/*
178	* Unaligned buffered read+write of head. Aligns the offset.
179	*/
180	if (offMisalign)
181	{
182	rc = VDRead(pDisk, off - offMisalign, abBuf, 512);
183	if (RT_SUCCESS(rc))
184	{
185	size_t const cbPart = RT_MIN(512 - offMisalign, cbWrite);
186	memcpy(&abBuf[offMisalign], pbSrc, cbPart);
187	rc = VDWrite(pDisk, off - offMisalign, abBuf, 512);
188	if (RT_SUCCESS(rc))
189	{
190	pbSrc += cbPart;
191	off += cbPart;
192	cbWrite -= cbPart;
193	}
194	}
195	}
196	else
197	rc = VINF_SUCCESS;
198
199	/*
200	* Aligned direct write.
201	*/
202	if ( RT_SUCCESS(rc)
203	&& cbWrite >= 512)
204	{
205	Assert(!(off % 512));
206	size_t cbPart = cbWrite - cbMisalign;
207	Assert(!(cbPart % 512));
208
209	if (RTListIsEmpty(&pDisk->ListFilterChainWrite))
210	{
211	rc = VDWrite(pDisk, off, pbSrc, cbPart);
212	if (RT_SUCCESS(rc))
213	{
214	pbSrc += cbPart;
215	off += cbPart;
216	cbWrite -= cbPart;
217	}
218	}
219	else
220	{
221	/* Filtered writes must be double buffered as the filter may need to modify the input buffer directly. */
222	do
223	{
224	size_t cbThisWrite = RT_MIN(cbPart, sizeof(abBuf));
225	rc = VDWrite(pDisk, off, memcpy(abBuf, pbSrc, cbThisWrite), cbThisWrite);
226	if (RT_SUCCESS(rc))
227	{
228	pbSrc += cbThisWrite;
229	off += cbThisWrite;
230	cbWrite -= cbThisWrite;
231	cbPart -= cbThisWrite;
232	}
233	else
234	break;
235	} while (cbPart > 0);
236	}
237	}
238
239	/*
240	* Unaligned buffered read+write of tail.
241	*/
242	if ( RT_SUCCESS(rc)
243	&& cbWrite > 0)
244	{
245	Assert(cbWrite == cbMisalign);
246	Assert(cbWrite < 512);
247	Assert(!(off % 512));
248
249	rc = VDRead(pDisk, off, abBuf, 512);
250	if (RT_SUCCESS(rc))
251	{
252	memcpy(abBuf, pbSrc, cbWrite);
253	rc = VDWrite(pDisk, off, abBuf, 512);
254	}
255	}
256	}
257
258	return rc;
259	}
260
261
262	/**
263	* @interface_method_impl{RTVFSOBJOPS,pfnClose}
264	*/
265	static DECLCALLBACK(int) vdVfsFile_Close(void *pvThis)
266	{
267	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
268
269	if (pThis->fFlags & VD_VFSFILE_DESTROY_ON_RELEASE)
270	VDDestroy(pThis->pDisk);
271
272	return VINF_SUCCESS;
273	}
274
275
276	/**
277	* @interface_method_impl{RTVFSOBJOPS,pfnQueryInfo}
278	*/
279	static DECLCALLBACK(int) vdVfsFile_QueryInfo(void *pvThis, PRTFSOBJINFO pObjInfo, RTFSOBJATTRADD enmAddAttr)
280	{
281	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
282	unsigned const cOpenImages = VDGetCount(pThis->pDisk);
283
284	pObjInfo->cbObject = VDGetSize(pThis->pDisk, cOpenImages - 1);
285	pObjInfo->cbAllocated = 0;
286	for (unsigned iImage = 0; iImage < cOpenImages; iImage++)
287	pObjInfo->cbAllocated += VDGetFileSize(pThis->pDisk, iImage);
288
289	/** @todo enumerate the disk images directly... */
290	RTTimeNow(&pObjInfo->AccessTime);
291	pObjInfo->BirthTime = pObjInfo->AccessTime;
292	pObjInfo->ChangeTime = pObjInfo->AccessTime;
293	pObjInfo->ModificationTime = pObjInfo->AccessTime;
294
295	pObjInfo->Attr.fMode = RTFS_DOS_NT_NORMAL \| RTFS_TYPE_FILE \| 0644;
296	pObjInfo->Attr.enmAdditional = enmAddAttr;
297	switch (enmAddAttr)
298	{
299	case RTFSOBJATTRADD_UNIX:
300	pObjInfo->Attr.u.Unix.uid = NIL_RTUID;
301	pObjInfo->Attr.u.Unix.gid = NIL_RTGID;
302	pObjInfo->Attr.u.Unix.cHardlinks = 1;
303	pObjInfo->Attr.u.Unix.INodeIdDevice = 0;
304	pObjInfo->Attr.u.Unix.INodeId = 0;
305	pObjInfo->Attr.u.Unix.fFlags = 0;
306	pObjInfo->Attr.u.Unix.GenerationId = 0;
307	pObjInfo->Attr.u.Unix.Device = 0;
308	break;
309
310	case RTFSOBJATTRADD_UNIX_OWNER:
311	pObjInfo->Attr.u.UnixOwner.uid = NIL_RTUID;
312	pObjInfo->Attr.u.UnixOwner.szName[0] = '\0';
313	break;
314	case RTFSOBJATTRADD_UNIX_GROUP:
315	pObjInfo->Attr.u.UnixGroup.gid = NIL_RTGID;
316	pObjInfo->Attr.u.UnixGroup.szName[0] = '\0';
317	break;
318	case RTFSOBJATTRADD_EASIZE:
319	pObjInfo->Attr.u.EASize.cb = 0;
320	break;
321
322	default:
323	AssertFailedReturn(VERR_INVALID_PARAMETER);
324	}
325
326	return VINF_SUCCESS;
327	}
328
329
330	/**
331	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnRead}
332	*/
333	static DECLCALLBACK(int) vdVfsFile_Read(void pvThis, RTFOFF off, PCRTSGBUF pSgBuf, bool fBlocking, size_t pcbRead)
334	{
335	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
336
337	Assert(pSgBuf->cSegs == 1);
338	NOREF(fBlocking);
339
340	/*
341	* Find the current position and check if it's within the volume.
342	*/
343	uint64_t offUnsigned = off < 0 ? pThis->offCurPos : (uint64_t)off;
344	uint64_t const cbImage = VDGetSize(pThis->pDisk, VD_LAST_IMAGE);
345	if (offUnsigned >= cbImage)
346	{
347	if (pcbRead)
348	{
349	*pcbRead = 0;
350	pThis->offCurPos = cbImage;
351	return VINF_EOF;
352	}
353	return VERR_EOF;
354	}
355
356	int rc = VINF_SUCCESS;
357	size_t cbLeftToRead = pSgBuf->paSegs[0].cbSeg;
358	if (offUnsigned + cbLeftToRead <= cbImage)
359	{
360	if (pcbRead)
361	*pcbRead = cbLeftToRead;
362	}
363	else
364	{
365	if (!pcbRead)
366	return VERR_EOF;
367	*pcbRead = cbLeftToRead = (size_t)(cbImage - offUnsigned);
368	rc = VINF_EOF;
369	}
370
371	/*
372	* Ok, we've got a valid stretch within the file. Do the reading.
373	*/
374	if (cbLeftToRead > 0)
375	{
376	int rc2 = vdReadHelper(pThis->pDisk, offUnsigned, pSgBuf->paSegs[0].pvSeg, cbLeftToRead);
377	if (RT_SUCCESS(rc2))
378	offUnsigned += cbLeftToRead;
379	else
380	rc = rc2;
381	}
382
383	pThis->offCurPos = offUnsigned;
384	return rc;
385	}
386
387
388	/**
389	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnWrite}
390	*/
391	static DECLCALLBACK(int) vdVfsFile_Write(void pvThis, RTFOFF off, PCRTSGBUF pSgBuf, bool fBlocking, size_t pcbWritten)
392	{
393	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
394
395	Assert(pSgBuf->cSegs == 1);
396	NOREF(fBlocking);
397
398	/*
399	* Find the current position and check if it's within the volume.
400	* Writing beyond the end of a volume is not supported.
401	*/
402	uint64_t offUnsigned = off < 0 ? pThis->offCurPos : (uint64_t)off;
403	uint64_t const cbImage = VDGetSize(pThis->pDisk, VD_LAST_IMAGE);
404	if (offUnsigned >= cbImage)
405	{
406	if (pcbWritten)
407	{
408	*pcbWritten = 0;
409	pThis->offCurPos = cbImage;
410	}
411	return VERR_EOF;
412	}
413
414	size_t cbLeftToWrite;
415	if (offUnsigned + pSgBuf->paSegs[0].cbSeg <= cbImage)
416	{
417	cbLeftToWrite = pSgBuf->paSegs[0].cbSeg;
418	if (pcbWritten)
419	*pcbWritten = cbLeftToWrite;
420	}
421	else
422	{
423	if (!pcbWritten)
424	return VERR_EOF;
425	*pcbWritten = cbLeftToWrite = (size_t)(cbImage - offUnsigned);
426	}
427
428	/*
429	* Ok, we've got a valid stretch within the file. Do the reading.
430	*/
431	int rc = VINF_SUCCESS;
432	if (cbLeftToWrite > 0)
433	{
434	rc = vdWriteHelper(pThis->pDisk, offUnsigned, pSgBuf->paSegs[0].pvSeg, cbLeftToWrite);
435	if (RT_SUCCESS(rc))
436	offUnsigned += cbLeftToWrite;
437	}
438
439	pThis->offCurPos = offUnsigned;
440	return rc;
441	}
442
443
444	/**
445	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnFlush}
446	*/
447	static DECLCALLBACK(int) vdVfsFile_Flush(void *pvThis)
448	{
449	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
450	return VDFlush(pThis->pDisk);
451	}
452
453
454	/**
455	* @interface_method_impl{RTVFSIOSTREAMOPS,pfnTell}
456	*/
457	static DECLCALLBACK(int) vdVfsFile_Tell(void *pvThis, PRTFOFF poffActual)
458	{
459	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
460	*poffActual = pThis->offCurPos;
461	return VINF_SUCCESS;
462	}
463
464
465	/**
466	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetMode}
467	*/
468	static DECLCALLBACK(int) vdVfsFile_SetMode(void *pvThis, RTFMODE fMode, RTFMODE fMask)
469	{
470	NOREF(pvThis);
471	NOREF(fMode);
472	NOREF(fMask);
473	return VERR_NOT_SUPPORTED;
474	}
475
476
477	/**
478	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetTimes}
479	*/
480	static DECLCALLBACK(int) vdVfsFile_SetTimes(void *pvThis, PCRTTIMESPEC pAccessTime, PCRTTIMESPEC pModificationTime,
481	PCRTTIMESPEC pChangeTime, PCRTTIMESPEC pBirthTime)
482	{
483	NOREF(pvThis);
484	NOREF(pAccessTime);
485	NOREF(pModificationTime);
486	NOREF(pChangeTime);
487	NOREF(pBirthTime);
488	return VERR_NOT_SUPPORTED;
489	}
490
491
492	/**
493	* @interface_method_impl{RTVFSOBJSETOPS,pfnSetOwner}
494	*/
495	static DECLCALLBACK(int) vdVfsFile_SetOwner(void *pvThis, RTUID uid, RTGID gid)
496	{
497	NOREF(pvThis);
498	NOREF(uid);
499	NOREF(gid);
500	return VERR_NOT_SUPPORTED;
501	}
502
503
504	/**
505	* @interface_method_impl{RTVFSFILEOPS,pfnSeek}
506	*/
507	static DECLCALLBACK(int) vdVfsFile_Seek(void *pvThis, RTFOFF offSeek, unsigned uMethod, PRTFOFF poffActual)
508	{
509	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
510
511	/*
512	* Seek relative to which position.
513	*/
514	uint64_t offWrt;
515	switch (uMethod)
516	{
517	case RTFILE_SEEK_BEGIN:
518	offWrt = 0;
519	break;
520
521	case RTFILE_SEEK_CURRENT:
522	offWrt = pThis->offCurPos;
523	break;
524
525	case RTFILE_SEEK_END:
526	offWrt = VDGetSize(pThis->pDisk, VD_LAST_IMAGE);
527	break;
528
529	default:
530	return VERR_INTERNAL_ERROR_5;
531	}
532
533	/*
534	* Calc new position, take care to stay without bounds.
535	*/
536	uint64_t offNew;
537	if (offSeek == 0)
538	offNew = offWrt;
539	else if (offSeek > 0)
540	{
541	offNew = offWrt + offSeek;
542	if ( offNew < offWrt
543	\|\| offNew > RTFOFF_MAX)
544	offNew = RTFOFF_MAX;
545	}
546	else if ((uint64_t)-offSeek < offWrt)
547	offNew = offWrt + offSeek;
548	else
549	offNew = 0;
550
551	/*
552	* Update the state and set return value.
553	*/
554	pThis->offCurPos = offNew;
555
556	*poffActual = offNew;
557	return VINF_SUCCESS;
558	}
559
560
561	/**
562	* @interface_method_impl{RTVFSFILEOPS,pfnQuerySize}
563	*/
564	static DECLCALLBACK(int) vdVfsFile_QuerySize(void pvThis, uint64_t pcbFile)
565	{
566	PVDVFSFILE pThis = (PVDVFSFILE)pvThis;
567	*pcbFile = VDGetSize(pThis->pDisk, VD_LAST_IMAGE);
568	return VINF_SUCCESS;
569	}
570
571
572	/**
573	* Standard file operations.
574	*/
575	DECL_HIDDEN_CONST(const RTVFSFILEOPS) g_vdVfsStdFileOps =
576	{
577	{ /* Stream */
578	{ /* Obj */
579	RTVFSOBJOPS_VERSION,
580	RTVFSOBJTYPE_FILE,
581	"VDFile",
582	vdVfsFile_Close,
583	vdVfsFile_QueryInfo,
584	RTVFSOBJOPS_VERSION
585	},
586	RTVFSIOSTREAMOPS_VERSION,
587	RTVFSIOSTREAMOPS_FEAT_NO_SG,
588	vdVfsFile_Read,
589	vdVfsFile_Write,
590	vdVfsFile_Flush,
591	NULL /PollOne/,
592	vdVfsFile_Tell,
593	NULL /Skip/,
594	NULL /ZeroFill/,
595	RTVFSIOSTREAMOPS_VERSION,
596	},
597	RTVFSFILEOPS_VERSION,
598	/RTVFSIOFILEOPS_FEAT_NO_AT_OFFSET/ 0,
599	{ /* ObjSet */
600	RTVFSOBJSETOPS_VERSION,
601	RT_UOFFSETOF(RTVFSFILEOPS, ObjSet) - RT_UOFFSETOF(RTVFSFILEOPS, Stream.Obj),
602	vdVfsFile_SetMode,
603	vdVfsFile_SetTimes,
604	vdVfsFile_SetOwner,
605	RTVFSOBJSETOPS_VERSION
606	},
607	vdVfsFile_Seek,
608	vdVfsFile_QuerySize,
609	NULL /SetSize/,
610	NULL /QueryMaxSize/,
611	RTVFSFILEOPS_VERSION
612	};
613
614
615	VBOXDDU_DECL(int) VDCreateVfsFileFromDisk(PVDISK pDisk, uint32_t fFlags,
616	PRTVFSFILE phVfsFile)
617	{
618	AssertPtrReturn(pDisk, VERR_INVALID_HANDLE);
619	AssertPtrReturn(phVfsFile, VERR_INVALID_POINTER);
620	AssertReturn((fFlags & ~VD_VFSFILE_FLAGS_MASK) == 0, VERR_INVALID_PARAMETER);
621
622	/*
623	* Create the volume file.
624	*/
625	RTVFSFILE hVfsFile;
626	PVDVFSFILE pThis;
627	int rc = RTVfsNewFile(&g_vdVfsStdFileOps, sizeof(*pThis), RTFILE_O_OPEN \| RTFILE_O_READ \| RTFILE_O_WRITE,
628	NIL_RTVFS, NIL_RTVFSLOCK, &hVfsFile, (void **)&pThis);
629	if (RT_SUCCESS(rc))
630	{
631	pThis->offCurPos = 0;
632	pThis->pDisk = pDisk;
633	pThis->fFlags = fFlags;
634
635	*phVfsFile = hVfsFile;
636	return VINF_SUCCESS;
637	}
638
639	return rc;
640	}
641
642
643	/**
644	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnValidate}
645	*/
646	static DECLCALLBACK(int) vdVfsChain_Validate(PCRTVFSCHAINELEMENTREG pProviderReg, PRTVFSCHAINSPEC pSpec,
647	PRTVFSCHAINELEMSPEC pElement, uint32_t *poffError, PRTERRINFO pErrInfo)
648	{
649	RT_NOREF(pProviderReg, pSpec);
650
651	/*
652	* Basic checks.
653	*/
654	if (pElement->enmTypeIn != RTVFSOBJTYPE_INVALID)
655	return VERR_VFS_CHAIN_MUST_BE_FIRST_ELEMENT;
656	if ( pElement->enmType != RTVFSOBJTYPE_FILE
657	&& pElement->enmType != RTVFSOBJTYPE_IO_STREAM)
658	return VERR_VFS_CHAIN_ONLY_FILE_OR_IOS;
659
660	if (pElement->cArgs < 1)
661	return VERR_VFS_CHAIN_AT_LEAST_ONE_ARG;
662
663	/*
664	* Parse the flag if present, save in pElement->uProvider.
665	*/
666	uint32_t fFlags = (pSpec->fOpenFile & RTFILE_O_ACCESS_MASK) == RTFILE_O_READ
667	? VD_OPEN_FLAGS_READONLY : VD_OPEN_FLAGS_NORMAL;
668	if (pElement->cArgs > 1)
669	{
670	pElement->paArgs[pElement->cArgs - 1].uProvider = true; /* indicates flags */
671	const char *psz = pElement->paArgs[pElement->cArgs - 1].psz;
672	if (*psz)
673	{
674	if ( !strcmp(psz, "ro")
675	\|\| !strcmp(psz, "r"))
676	{
677	fFlags &= ~(VD_OPEN_FLAGS_READONLY \| VD_OPEN_FLAGS_NORMAL);
678	fFlags \|= VD_OPEN_FLAGS_READONLY;
679	}
680	else if (!strcmp(psz, "rw"))
681	{
682	fFlags &= ~(VD_OPEN_FLAGS_READONLY \| VD_OPEN_FLAGS_NORMAL);
683	fFlags \|= VD_OPEN_FLAGS_NORMAL;
684	}
685	else if (strlen(psz) <= 4)
686	{
687	*poffError = pElement->paArgs[pElement->cArgs - 1].offSpec;
688	return RTErrInfoSet(pErrInfo, VERR_VFS_CHAIN_INVALID_ARGUMENT, "Expected 'ro' or 'rw' as argument");
689	}
690	else
691	pElement->paArgs[pElement->cArgs - 1].uProvider = false; /* indicates no flags */
692	}
693	}
694
695	pElement->uProvider = fFlags;
696	if ( pElement->cArgs > 2
697	\|\| (pElement->cArgs == 2 && !pElement->paArgs[pElement->cArgs - 1].uProvider))
698	pElement->uProvider \|= RT_BIT_64(63);
699	return VINF_SUCCESS;
700	}
701
702
703	/**
704	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnInstantiate}
705	*/
706	static DECLCALLBACK(int) vdVfsChain_Instantiate(PCRTVFSCHAINELEMENTREG pProviderReg, PCRTVFSCHAINSPEC pSpec,
707	PCRTVFSCHAINELEMSPEC pElement, RTVFSOBJ hPrevVfsObj,
708	PRTVFSOBJ phVfsObj, uint32_t *poffError, PRTERRINFO pErrInfo)
709	{
710	RT_NOREF(pProviderReg, pSpec, poffError, pErrInfo);
711	AssertReturn(hPrevVfsObj == NIL_RTVFSOBJ, VERR_VFS_CHAIN_IPE);
712
713	/* Determin the format. */
714	char *pszFormat = NULL;
715	VDTYPE enmType = VDTYPE_INVALID;
716	int rc = VDGetFormat(NULL, NULL, pElement->paArgs[0].psz, &pszFormat, &enmType);
717	if (RT_SUCCESS(rc))
718	{
719	PVDISK pDisk = NULL;
720	rc = VDCreate(NULL, enmType, &pDisk);
721	if (RT_SUCCESS(rc))
722	{
723	if (!(pElement->uProvider & RT_BIT_64(63)))
724	rc = VDOpen(pDisk, pszFormat, pElement->paArgs[0].psz, (uint32_t)pElement->uProvider, NULL);
725	else
726	{
727	uint32_t cChain = pElement->cArgs;
728	if (pElement->cArgs >= 2 && pElement->paArgs[pElement->cArgs - 1].uProvider != 0)
729	cChain--;
730	uint32_t const fFinal = (uint32_t)pElement->uProvider;
731	uint32_t const fReadOnly = (fFinal & ~(VD_OPEN_FLAGS_READONLY \| VD_OPEN_FLAGS_NORMAL)) \| VD_OPEN_FLAGS_READONLY;
732	uint32_t iChain;
733	for (iChain = 0; iChain < cChain && RT_SUCCESS(rc); iChain++)
734	rc = VDOpen(pDisk, pszFormat, pElement->paArgs[iChain].psz, iChain + 1 >= cChain ? fFinal : fReadOnly, NULL);
735	}
736	if (RT_SUCCESS(rc))
737	{
738	RTVFSFILE hVfsFile;
739	rc = VDCreateVfsFileFromDisk(pDisk, VD_VFSFILE_DESTROY_ON_RELEASE, &hVfsFile);
740	if (RT_SUCCESS(rc))
741	{
742	RTStrFree(pszFormat);
743
744	*phVfsObj = RTVfsObjFromFile(hVfsFile);
745	RTVfsFileRelease(hVfsFile);
746
747	if (*phVfsObj != NIL_RTVFSOBJ)
748	return VINF_SUCCESS;
749	return VERR_VFS_CHAIN_CAST_FAILED;
750	}
751	}
752	VDDestroy(pDisk);
753	}
754	RTStrFree(pszFormat);
755	}
756	return rc;
757	}
758
759
760	/**
761	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnCanReuseElement}
762	*/
763	static DECLCALLBACK(bool) vdVfsChain_CanReuseElement(PCRTVFSCHAINELEMENTREG pProviderReg,
764	PCRTVFSCHAINSPEC pSpec, PCRTVFSCHAINELEMSPEC pElement,
765	PCRTVFSCHAINSPEC pReuseSpec, PCRTVFSCHAINELEMSPEC pReuseElement)
766	{
767	RT_NOREF(pProviderReg, pSpec, pElement, pReuseSpec, pReuseElement);
768	return false;
769	}
770
771
772	/** VFS chain element 'file'. */
773	static RTVFSCHAINELEMENTREG g_rtVfsChainIsoFsVolReg =
774	{
775	/* uVersion = */ RTVFSCHAINELEMENTREG_VERSION,
776	/* fReserved = */ 0,
777	/* pszName = */ "vd",
778	/* ListEntry = */ { NULL, NULL },
779	/* pszHelp = */ "Opens a container image using the VD API.\n"
780	"To open a snapshot chain, start with the root image and end with the more recent diff image.\n"
781	"The final argument can be a flag 'ro' or 'r' for read-only, 'rw' for read-write.",
782	/* pfnValidate = */ vdVfsChain_Validate,
783	/* pfnInstantiate = */ vdVfsChain_Instantiate,
784	/* pfnCanReuseElement = */ vdVfsChain_CanReuseElement,
785	/* uEndMarker = */ RTVFSCHAINELEMENTREG_VERSION
786	};
787
788	RTVFSCHAIN_AUTO_REGISTER_ELEMENT_PROVIDER(&g_rtVfsChainIsoFsVolReg, rtVfsChainIsoFsVolReg);
789

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source: vbox/trunk/src/VBox/Storage/VDVfs.cpp@ 76389

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