vfsmount.cpp@ 96563

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1	/* $Id: vfsmount.cpp 96407 2022-08-22 17:43:14Z vboxsync $ */
2	/** @file
3	* IPRT - Virtual File System, Mounting.
4	*/
5
6	/*
7	* Copyright (C) 2012-2022 Oracle and/or its affiliates.
8	*
9	* This file is part of VirtualBox base platform packages, as
10	* available from https://www.virtualbox.org.
11	*
12	* This program is free software; you can redistribute it and/or
13	* modify it under the terms of the GNU General Public License
14	* as published by the Free Software Foundation, in version 3 of the
15	* License.
16	*
17	* This program is distributed in the hope that it will be useful, but
18	* WITHOUT ANY WARRANTY; without even the implied warranty of
19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20	* General Public License for more details.
21	*
22	* You should have received a copy of the GNU General Public License
23	* along with this program; if not, see <https://www.gnu.org/licenses>.
24	*
25	* The contents of this file may alternatively be used under the terms
26	* of the Common Development and Distribution License Version 1.0
27	* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
28	* in the VirtualBox distribution, in which case the provisions of the
29	* CDDL are applicable instead of those of the GPL.
30	*
31	* You may elect to license modified versions of this file under the
32	* terms and conditions of either the GPL or the CDDL or both.
33	*
34	* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
35	*/
36
37
38	/*********************************************************************************************************************************
39	* Header Files *
40	*********************************************************************************************************************************/
41	#define LOG_GROUP RTLOGGROUP_VFS
42	#include <iprt/vfs.h>
43
44	#include <iprt/asm.h>
45	#include <iprt/assert.h>
46	#include <iprt/err.h>
47	#include <iprt/file.h>
48	#include <iprt/fsvfs.h>
49	#include <iprt/mem.h>
50	#include <iprt/log.h>
51	#include <iprt/string.h>
52	#include <iprt/vfslowlevel.h>
53
54	#include <iprt/formats/fat.h>
55	#include <iprt/formats/iso9660.h>
56	#include <iprt/formats/udf.h>
57	#include <iprt/formats/ext.h>
58
59
60	/*********************************************************************************************************************************
61	* Structures and Typedefs *
62	*********************************************************************************************************************************/
63	/** Buffer structure for the detection routines. */
64	typedef union RTVFSMOUNTBUF
65	{
66	uint8_t ab[2048];
67	uint32_t au32[2048/4];
68	FATBOOTSECTOR Bootsector;
69	ISO9660VOLDESCHDR IsoHdr;
70	} RTVFSMOUNTBUF;
71	AssertCompileSize(RTVFSMOUNTBUF, 2048);
72	typedef RTVFSMOUNTBUF *PRTVFSMOUNTBUF;
73
74
75
76	/**
77	* Checks if the given 2K sector at offset 32KB looks like ISO-9660 or UDF.
78	*
79	* @returns true if likely ISO or UDF, otherwise false.
80	* @param pVolDescHdr Whatever is at offset 32KB. 2KB buffer.
81	*/
82	static bool rtVfsMountIsIsoFs(PCISO9660VOLDESCHDR pVolDescHdr)
83	{
84	if ( memcmp(pVolDescHdr->achStdId, RT_STR_TUPLE(ISO9660VOLDESC_STD_ID)) == 0
85	&& pVolDescHdr->bDescType <= ISO9660VOLDESC_TYPE_PARTITION
86	&& pVolDescHdr->bDescVersion != 0
87	&& pVolDescHdr->bDescVersion <= 3 /* don't be too picky, just increase the likelyhood */ )
88	return true;
89
90	if ( memcmp(pVolDescHdr->achStdId, RT_STR_TUPLE(UDF_EXT_VOL_DESC_STD_ID_BEGIN)) == 0
91	&& pVolDescHdr->bDescType == UDF_EXT_VOL_DESC_TYPE
92	&& pVolDescHdr->bDescVersion == UDF_EXT_VOL_DESC_VERSION)
93	return true;
94
95	return false;
96	}
97
98
99	/**
100	* Check if the given bootsector is a NTFS boot sector.
101	*
102	* @returns true if NTFS, false if not.
103	* @param pBootSector The boot sector to inspect.
104	*/
105	static bool rtVfsMountIsNtfs(PCFATBOOTSECTOR pBootSector)
106	{
107	if (memcmp(pBootSector->achOemName, RT_STR_TUPLE("NTFS ")) != 0)
108	return false;
109
110	uint16_t cbSector = RT_LE2H_U16(pBootSector->Bpb.Bpb331.cbSector);
111	if ( cbSector < 0x100
112	\|\| cbSector >= 0x1000
113	\|\| (cbSector & 0xff) != 0)
114	{
115	Log2(("rtVfsMountIsNtfs: cbSector=%#x: out of range\n", cbSector));
116	return false;
117	}
118
119	if ( !RT_IS_POWER_OF_TWO(pBootSector->Bpb.Bpb331.cSectorsPerCluster)
120	\|\| pBootSector->Bpb.Bpb331.cSectorsPerCluster == 0
121	\|\| pBootSector->Bpb.Bpb331.cSectorsPerCluster > 128)
122	{
123	Log2(("rtVfsMountIsNtfs: cSectorsPerCluster=%#x: out of range\n", pBootSector->Bpb.Bpb331.cSectorsPerCluster));
124	return false;
125	}
126
127	if ((uint32_t)pBootSector->Bpb.Bpb331.cSectorsPerCluster * cbSector > _64K)
128	{
129	Log2(("rtVfsMountIsNtfs: cSectorsPerCluster=%#x * cbSector=%#x => %#x: out of range\n",
130	pBootSector->Bpb.Bpb331.cSectorsPerCluster, cbSector,
131	(uint32_t)pBootSector->Bpb.Bpb331.cSectorsPerCluster * cbSector));
132	return false;
133	}
134
135	if ( pBootSector->Bpb.Bpb331.cReservedSectors != 0
136	\|\| pBootSector->Bpb.Bpb331.cMaxRootDirEntries != 0
137	\|\| pBootSector->Bpb.Bpb331.cTotalSectors16 != 0
138	\|\| pBootSector->Bpb.Bpb331.cTotalSectors32 != 0
139	\|\| pBootSector->Bpb.Bpb331.cSectorsPerFat != 0
140	\|\| pBootSector->Bpb.Bpb331.cFats != 0)
141	{
142	Log2(("rtVfsMountIsNtfs: cReservedSectors=%#x cMaxRootDirEntries=%#x cTotalSectors=%#x cTotalSectors32=%#x cSectorsPerFat=%#x cFats=%#x: should all be zero, but one or more aren't\n",
143	RT_LE2H_U16(pBootSector->Bpb.Bpb331.cReservedSectors),
144	RT_LE2H_U16(pBootSector->Bpb.Bpb331.cMaxRootDirEntries),
145	RT_LE2H_U16(pBootSector->Bpb.Bpb331.cTotalSectors16),
146	RT_LE2H_U32(pBootSector->Bpb.Bpb331.cTotalSectors32),
147	RT_LE2H_U16(pBootSector->Bpb.Bpb331.cSectorsPerFat),
148	pBootSector->Bpb.Bpb331.cFats));
149	return false;
150	}
151
152	/** @todo NTFS specific checks: MFT cluster number, cluster per index block. */
153
154	return true;
155	}
156
157
158	/**
159	* Check if the given bootsector is a HPFS boot sector.
160	*
161	* @returns true if NTFS, false if not.
162	* @param pBootSector The boot sector to inspect.
163	* @param hVfsFileIn The volume file.
164	* @param pBuf2 A 2nd buffer.
165	*/
166	static bool rtVfsMountIsHpfs(PCFATBOOTSECTOR pBootSector, RTVFSFILE hVfsFileIn, PRTVFSMOUNTBUF pBuf2)
167	{
168	if (memcmp(pBootSector->Bpb.Ebpb.achType, RT_STR_TUPLE("HPFS ")) != 0)
169	return false;
170
171	/* Superblock is at sector 16, spare superblock at 17. */
172	int rc = RTVfsFileReadAt(hVfsFileIn, 16 * 512, pBuf2, 512 * 2, NULL);
173	if (RT_FAILURE(rc))
174	{
175	Log2(("rtVfsMountIsHpfs: Error reading superblock: %Rrc\n", rc));
176	return false;
177	}
178
179	if ( RT_LE2H_U32(pBuf2->au32[0]) != UINT32_C(0xf995e849)
180	\|\| RT_LE2H_U32(pBuf2->au32[1]) != UINT32_C(0xfa53e9c5)
181	\|\| RT_LE2H_U32(pBuf2->au32[512/4 + 0]) != UINT32_C(0xf9911849)
182	\|\| RT_LE2H_U32(pBuf2->au32[512/4 + 1]) != UINT32_C(0xfa5229c5))
183	{
184	Log2(("rtVfsMountIsHpfs: Superblock or spare superblock signature mismatch: %#x %#x %#x %#x\n",
185	RT_LE2H_U32(pBuf2->au32[0]), RT_LE2H_U32(pBuf2->au32[1]),
186	RT_LE2H_U32(pBuf2->au32[512/4 + 0]), RT_LE2H_U32(pBuf2->au32[512/4 + 1]) ));
187	return false;
188	}
189
190	return true;
191	}
192
193
194	/**
195	* Check if the given bootsector is a FAT boot sector.
196	*
197	* @returns true if NTFS, false if not.
198	* @param pBootSector The boot sector to inspect.
199	* @param pbRaw Pointer to the raw boot sector buffer.
200	* @param cbRaw Number of bytes read starting with the boot
201	* sector (which @a pbRaw points to).
202	* @param hVfsFileIn The volume file.
203	* @param pBuf2 A 2nd buffer.
204	*/
205	static bool rtVfsMountIsFat(PCFATBOOTSECTOR pBootSector, uint8_t const *pbRaw, size_t cbRaw,
206	RTVFSFILE hVfsFileIn, PRTVFSMOUNTBUF pBuf2)
207	{
208	Assert(cbRaw >= 1024);
209
210	/*
211	* Check the DOS signature first. The PC-DOS 1.0 boot floppy does not have
212	* a signature and we ASSUME this is the case for all floppies formated by it.
213	*/
214	if (pBootSector->uSignature != FATBOOTSECTOR_SIGNATURE)
215	{
216	if (pBootSector->uSignature != 0)
217	return false;
218
219	/*
220	* PC-DOS 1.0 does a 2fh byte short jump w/o any NOP following it.
221	* Instead the following are three words and a 9 byte build date
222	* string. The remaining space is zero filled.
223	*
224	* Note! No idea how this would look like for 8" floppies, only got 5"1/4'.
225	*
226	* ASSUME all non-BPB disks are using this format.
227	*/
228	if ( pBootSector->abJmp[0] != 0xeb /* jmp rel8 */
229	\|\| pBootSector->abJmp[1] < 0x2f
230	\|\| pBootSector->abJmp[1] >= 0x80
231	\|\| pBootSector->abJmp[2] == 0x90 /* nop */)
232	{
233	Log2(("rtVfsMountIsFat: No DOS v1.0 bootsector either - invalid jmp: %.3Rhxs\n", pBootSector->abJmp));
234	return false;
235	}
236
237	/* Check the FAT ID so we can tell if this is double or single sided, as well as being a valid FAT12 start. */
238	if ( (pbRaw[512] != 0xfe && pbRaw[0] != 0xff)
239	\|\| pbRaw[512 + 1] != 0xff
240	\|\| pbRaw[512 + 2] != 0xff)
241	{
242	Log2(("rtVfsMountIsFat: No DOS v1.0 bootsector either - unexpected start of FAT: %.3Rhxs\n", &pbRaw[512]));
243	return false;
244	}
245
246	uint32_t const offJump = 2 + pBootSector->abJmp[1];
247	uint32_t const offFirstZero = 2 /jmp / + 3 * 2 /* words / + 9 / date string */;
248	Assert(offFirstZero >= RT_UOFFSETOF(FATBOOTSECTOR, Bpb));
249	uint32_t const cbZeroPad = RT_MIN(offJump - offFirstZero,
250	sizeof(pBootSector->Bpb.Bpb20) - (offFirstZero - RT_UOFFSETOF(FATBOOTSECTOR, Bpb)));
251
252	if (!ASMMemIsAllU8((uint8_t const *)pBootSector + offFirstZero, cbZeroPad, 0))
253	{
254	Log2(("rtVfsMountIsFat: No DOS v1.0 bootsector either - expected zero padding %#x LB %#x: %.*Rhxs\n",
255	offFirstZero, cbZeroPad, cbZeroPad, (uint8_t const *)pBootSector + offFirstZero));
256	return false;
257	}
258	}
259	else
260	{
261	/*
262	* DOS 2.0 or later.
263	*
264	* Start by checking if we've got a known jump instruction first, because
265	* that will give us a max (E)BPB size hint.
266	*/
267	uint8_t offJmp = UINT8_MAX;
268	if ( pBootSector->abJmp[0] == 0xeb
269	&& pBootSector->abJmp[1] <= 0x7f)
270	offJmp = pBootSector->abJmp[1] + 2;
271	else if ( pBootSector->abJmp[0] == 0x90
272	&& pBootSector->abJmp[1] == 0xeb
273	&& pBootSector->abJmp[2] <= 0x7f)
274	offJmp = pBootSector->abJmp[2] + 3;
275	else if ( pBootSector->abJmp[0] == 0xe9
276	&& pBootSector->abJmp[2] <= 0x7f)
277	offJmp = RT_MIN(127, RT_MAKE_U16(pBootSector->abJmp[1], pBootSector->abJmp[2]));
278	uint8_t const cbMaxBpb = offJmp - RT_UOFFSETOF(FATBOOTSECTOR, Bpb);
279	if (cbMaxBpb < sizeof(FATBPB20))
280	{
281	Log2(("rtVfsMountIsFat: DOS signature, but jmp too short for any BPB: %#x (max %#x BPB)\n", offJmp, cbMaxBpb));
282	return false;
283	}
284
285	if ( pBootSector->Bpb.Bpb20.cFats == 0
286	\|\| pBootSector->Bpb.Bpb20.cFats > 4)
287	{
288	if (pBootSector->Bpb.Bpb20.cFats == 0)
289	Log2(("rtVfsMountIsFat: DOS signature, number of FATs is zero, so not FAT file system\n"));
290	else
291	Log2(("rtVfsMountIsFat: DOS signature, too many FATs: %#x\n", pBootSector->Bpb.Bpb20.cFats));
292	return false;
293	}
294
295	if (!FATBPB_MEDIA_IS_VALID(pBootSector->Bpb.Bpb20.bMedia))
296	{
297	Log2(("rtVfsMountIsFat: DOS signature, invalid media byte: %#x\n", pBootSector->Bpb.Bpb20.bMedia));
298	return false;
299	}
300
301	uint16_t cbSector = RT_LE2H_U16(pBootSector->Bpb.Bpb20.cbSector);
302	if ( cbSector != 512
303	&& cbSector != 4096
304	&& cbSector != 1024
305	&& cbSector != 128)
306	{
307	Log2(("rtVfsMountIsFat: DOS signature, unsupported sector size: %#x\n", cbSector));
308	return false;
309	}
310
311	if ( !RT_IS_POWER_OF_TWO(pBootSector->Bpb.Bpb20.cSectorsPerCluster)
312	\|\| !pBootSector->Bpb.Bpb20.cSectorsPerCluster)
313	{
314	Log2(("rtVfsMountIsFat: DOS signature, cluster size not non-zero power of two: %#x",
315	pBootSector->Bpb.Bpb20.cSectorsPerCluster));
316	return false;
317	}
318
319	uint16_t const cReservedSectors = RT_LE2H_U16(pBootSector->Bpb.Bpb20.cReservedSectors);
320	if ( cReservedSectors == 0
321	\|\| cReservedSectors >= _32K)
322	{
323	Log2(("rtVfsMountIsFat: DOS signature, bogus reserved sector count: %#x\n", cReservedSectors));
324	return false;
325	}
326
327	/*
328	* Match the media byte with the first FAT byte and check that the next
329	* 4 bits are set. (To match further bytes in the FAT we'd need to
330	* determin the FAT type, which is too much hazzle to do here.)
331	*/
332	uint8_t const *pbFat;
333	if ((size_t)cReservedSectors * cbSector < cbRaw)
334	pbFat = &pbRaw[cReservedSectors * cbSector];
335	else
336	{
337	int rc = RTVfsFileReadAt(hVfsFileIn, cReservedSectors * cbSector, pBuf2, 512, NULL);
338	if (RT_FAILURE(rc))
339	{
340	Log2(("rtVfsMountIsFat: error reading first FAT sector at %#x: %Rrc\n", cReservedSectors * cbSector, rc));
341	return false;
342	}
343	pbFat = pBuf2->ab;
344	}
345	if (*pbFat != pBootSector->Bpb.Bpb20.bMedia)
346	{
347	Log2(("rtVfsMountIsFat: Media byte and FAT ID mismatch: %#x vs %#x (%.8Rhxs)\n",
348	pbFat[0], pBootSector->Bpb.Bpb20.bMedia, pbFat));
349	return false;
350	}
351	if ((pbFat[1] & 0xf) != 0xf)
352	{
353	Log2(("rtVfsMountIsFat: Media byte and FAT ID mismatch: %#x vs %#x (%.8Rhxs)\n",
354	pbFat[0], pBootSector->Bpb.Bpb20.bMedia, pbFat));
355	return false;
356	}
357	}
358
359	return true;
360	}
361
362
363	/**
364	* Check if the given bootsector is an ext2/3/4 super block.
365	*
366	* @returns true if NTFS, false if not.
367	* @param pSuperBlock The ext2 superblock.
368	*/
369	static bool rtVfsMountIsExt(PCEXTSUPERBLOCK pSuperBlock)
370	{
371	if (RT_LE2H_U16(pSuperBlock->u16Signature) != EXT_SB_SIGNATURE)
372	return false;
373
374	uint32_t cShift = RT_LE2H_U32(pSuperBlock->cLogBlockSize);
375	if (cShift > 54)
376	{
377	Log2(("rtVfsMountIsExt: cLogBlockSize=%#x: out of range\n", cShift));
378	return false;
379	}
380
381	cShift = RT_LE2H_U32(pSuperBlock->cLogClusterSize);
382	if (cShift > 54)
383	{
384	Log2(("rtVfsMountIsExt: cLogClusterSize=%#x: out of range\n", cShift));
385	return false;
386	}
387
388	/* Some more checks here would be nice actually since a 16-bit word and a
389	couple of field limits doesn't feel all that conclusive. */
390
391	return true;
392	}
393
394
395	/**
396	* Does the file system detection and mounting.
397	*
398	* Since we only support a handful of file systems at the moment and the
399	* interface isn't yet extensible in any way, we combine the file system
400	* recognition code for all. This reduces the number of reads we need to do and
401	* avoids unnecessary processing.
402	*
403	* @returns IPRT status code.
404	* @param hVfsFileIn The volume file.
405	* @param fFlags RTVFSMTN_F_XXX.
406	* @param pBuf Pointer to the primary buffer
407	* @param pBuf2 Pointer to the secondary buffer.
408	* @param phVfs Where to return the .
409	* @param pErrInfo Where to return additional error information.
410	* Optional.
411	*/
412	static int rtVfsMountInner(RTVFSFILE hVfsFileIn, uint32_t fFlags, RTVFSMOUNTBUF *pBuf,
413	RTVFSMOUNTBUF *pBuf2, PRTVFS phVfs, PRTERRINFO pErrInfo)
414	{
415	AssertCompile(sizeof(*pBuf) >= ISO9660_SECTOR_SIZE);
416
417	/* Start by checking for ISO-9660 and UDFS since these may have confusing
418	data at the start of the volume. */
419	int rc = RTVfsFileReadAt(hVfsFileIn, _32K, pBuf, ISO9660_SECTOR_SIZE, NULL);
420	if (RT_SUCCESS(rc))
421	{
422	if (rtVfsMountIsIsoFs(&pBuf->IsoHdr))
423	{
424	Log(("RTVfsMount: Detected ISO-9660 or UDF.\n"));
425	return RTFsIso9660VolOpen(hVfsFileIn, 0 /fFlags/, phVfs, pErrInfo);
426	}
427	}
428
429	/* Now read the boot sector and whatever the next 1536 bytes may contain.
430	With ext2 superblock at 1024, we can recognize quite a bit thru this read. */
431	rc = RTVfsFileReadAt(hVfsFileIn, 0, pBuf, sizeof(*pBuf), NULL);
432	if (RT_FAILURE(rc))
433	return RTErrInfoSet(pErrInfo, rc, "Error reading boot sector");
434
435	if (rtVfsMountIsNtfs(&pBuf->Bootsector))
436	return RTFsNtfsVolOpen(hVfsFileIn, fFlags, 0 /fNtfsFlags/, phVfs, pErrInfo);
437
438	if (rtVfsMountIsHpfs(&pBuf->Bootsector, hVfsFileIn, pBuf2))
439	return RTERRINFO_LOG_SET(pErrInfo, VERR_VFS_UNSUPPORTED_FORMAT, "HPFS not yet supported");
440
441	if (rtVfsMountIsFat(&pBuf->Bootsector, pBuf->ab, sizeof(*pBuf), hVfsFileIn, pBuf2))
442	{
443	Log(("RTVfsMount: Detected ISO-9660 or UDF.\n"));
444	return RTFsFatVolOpen(hVfsFileIn, RT_BOOL(fFlags & RTVFSMNT_F_READ_ONLY), 0 /offBootSector/, phVfs, pErrInfo);
445	}
446
447	AssertCompile(sizeof(*pBuf) >= 1024 + sizeof(EXTSUPERBLOCK));
448	if (rtVfsMountIsExt((PCEXTSUPERBLOCK)&pBuf->ab[1024]))
449	{
450	Log(("RTVfsMount: Detected EXT2/3/4.\n"));
451	return RTFsExtVolOpen(hVfsFileIn, fFlags, 0 /fExt2Flags/, phVfs, pErrInfo);
452	}
453
454	return VERR_VFS_UNSUPPORTED_FORMAT;
455	}
456
457
458	RTDECL(int) RTVfsMountVol(RTVFSFILE hVfsFileIn, uint32_t fFlags, PRTVFS phVfs, PRTERRINFO pErrInfo)
459	{
460	AssertReturn(!(fFlags & ~RTVFSMNT_F_VALID_MASK), VERR_INVALID_FLAGS);
461	AssertPtrReturn(hVfsFileIn, VERR_INVALID_HANDLE);
462	AssertPtrReturn(phVfs, VERR_INVALID_HANDLE);
463
464	*phVfs = NIL_RTVFS;
465
466	RTVFSMOUNTBUF pBufs = (RTVFSMOUNTBUF )RTMemTmpAlloc(sizeof(pBufs) 2);
467	AssertReturn(pBufs, VERR_NO_TMP_MEMORY);
468
469	int rc = rtVfsMountInner(hVfsFileIn, fFlags, pBufs, pBufs + 1, phVfs, pErrInfo);
470
471	RTMemTmpFree(pBufs);
472
473	return rc;
474	}
475
476
477	/**
478	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnValidate}
479	*/
480	static DECLCALLBACK(int) rtVfsChainMountVol_Validate(PCRTVFSCHAINELEMENTREG pProviderReg, PRTVFSCHAINSPEC pSpec,
481	PRTVFSCHAINELEMSPEC pElement, uint32_t *poffError, PRTERRINFO pErrInfo)
482	{
483	RT_NOREF(pProviderReg);
484
485	/*
486	* Basic checks.
487	*/
488	if (pElement->enmTypeIn != RTVFSOBJTYPE_FILE)
489	return pElement->enmTypeIn == RTVFSOBJTYPE_INVALID ? VERR_VFS_CHAIN_CANNOT_BE_FIRST_ELEMENT : VERR_VFS_CHAIN_TAKES_FILE;
490	if ( pElement->enmType != RTVFSOBJTYPE_VFS
491	&& pElement->enmType != RTVFSOBJTYPE_DIR)
492	return VERR_VFS_CHAIN_ONLY_DIR_OR_VFS;
493	if (pElement->cArgs > 1)
494	return VERR_VFS_CHAIN_AT_MOST_ONE_ARG;
495
496	/*
497	* Parse the flag if present, save in pElement->uProvider.
498	*/
499	bool fReadOnly = (pSpec->fOpenFile & RTFILE_O_ACCESS_MASK) == RTFILE_O_READ;
500	if (pElement->cArgs > 0)
501	{
502	const char *psz = pElement->paArgs[0].psz;
503	if (*psz)
504	{
505	if (!strcmp(psz, "ro"))
506	fReadOnly = true;
507	else if (!strcmp(psz, "rw"))
508	fReadOnly = false;
509	else
510	{
511	*poffError = pElement->paArgs[0].offSpec;
512	return RTErrInfoSet(pErrInfo, VERR_VFS_CHAIN_INVALID_ARGUMENT, "Expected 'ro' or 'rw' as argument");
513	}
514	}
515	}
516
517	pElement->uProvider = fReadOnly ? RTVFSMNT_F_READ_ONLY : 0;
518	return VINF_SUCCESS;
519	}
520
521
522	/**
523	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnInstantiate}
524	*/
525	static DECLCALLBACK(int) rtVfsChainMountVol_Instantiate(PCRTVFSCHAINELEMENTREG pProviderReg, PCRTVFSCHAINSPEC pSpec,
526	PCRTVFSCHAINELEMSPEC pElement, RTVFSOBJ hPrevVfsObj,
527	PRTVFSOBJ phVfsObj, uint32_t *poffError, PRTERRINFO pErrInfo)
528	{
529	RT_NOREF(pProviderReg, pSpec, poffError);
530
531	int rc;
532	RTVFSFILE hVfsFileIn = RTVfsObjToFile(hPrevVfsObj);
533	if (hVfsFileIn != NIL_RTVFSFILE)
534	{
535	RTVFS hVfs;
536	rc = RTVfsMountVol(hVfsFileIn, (uint32_t)pElement->uProvider, &hVfs, pErrInfo);
537	RTVfsFileRelease(hVfsFileIn);
538	if (RT_SUCCESS(rc))
539	{
540	*phVfsObj = RTVfsObjFromVfs(hVfs);
541	RTVfsRelease(hVfs);
542	if (*phVfsObj != NIL_RTVFSOBJ)
543	return VINF_SUCCESS;
544	rc = VERR_VFS_CHAIN_CAST_FAILED;
545	}
546	}
547	else
548	rc = VERR_VFS_CHAIN_CAST_FAILED;
549	return rc;
550	}
551
552
553	/**
554	* @interface_method_impl{RTVFSCHAINELEMENTREG,pfnCanReuseElement}
555	*/
556	static DECLCALLBACK(bool) rtVfsChainMountVol_CanReuseElement(PCRTVFSCHAINELEMENTREG pProviderReg,
557	PCRTVFSCHAINSPEC pSpec, PCRTVFSCHAINELEMSPEC pElement,
558	PCRTVFSCHAINSPEC pReuseSpec, PCRTVFSCHAINELEMSPEC pReuseElement)
559	{
560	RT_NOREF(pProviderReg, pSpec, pReuseSpec);
561	if ( pElement->paArgs[0].uProvider == pReuseElement->paArgs[0].uProvider
562	\|\| !pReuseElement->paArgs[0].uProvider)
563	return true;
564	return false;
565	}
566
567
568	/** VFS chain element 'file'. */
569	static RTVFSCHAINELEMENTREG g_rtVfsChainMountVolReg =
570	{
571	/* uVersion = */ RTVFSCHAINELEMENTREG_VERSION,
572	/* fReserved = */ 0,
573	/* pszName = */ "mount",
574	/* ListEntry = */ { NULL, NULL },
575	/* pszHelp = */ "Open a file system, requires a file object on the left side.\n"
576	"First argument is an optional 'ro' (read-only) or 'rw' (read-write) flag.\n",
577	/* pfnValidate = */ rtVfsChainMountVol_Validate,
578	/* pfnInstantiate = */ rtVfsChainMountVol_Instantiate,
579	/* pfnCanReuseElement = */ rtVfsChainMountVol_CanReuseElement,
580	/* uEndMarker = */ RTVFSCHAINELEMENTREG_VERSION
581	};
582
583	RTVFSCHAIN_AUTO_REGISTER_ELEMENT_PROVIDER(&g_rtVfsChainMountVolReg, rtVfsChainMountVolReg);
584

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source: vbox/trunk/src/VBox/Runtime/common/vfs/vfsmount.cpp@ 96563

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