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source: vbox/trunk/src/VBox/Runtime/common/filesystem/filesystemext.cpp@ 49456

Last change on this file since 49456 was 46186, checked in by vboxsync, 12 years ago

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1/* $Id: filesystemext.cpp 46186 2013-05-21 06:30:21Z vboxsync $ */
2/** @file
3 * IPRT Filesystem API (FileSys) - ext2/3 format.
4 */
5
6/*
7 * Copyright (C) 2012 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 * The contents of this file may alternatively be used under the terms
18 * of the Common Development and Distribution License Version 1.0
19 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20 * VirtualBox OSE distribution, in which case the provisions of the
21 * CDDL are applicable instead of those of the GPL.
22 *
23 * You may elect to license modified versions of this file under the
24 * terms and conditions of either the GPL or the CDDL or both.
25 */
26
27
28/*******************************************************************************
29* Header Files *
30*******************************************************************************/
31#define LOG_GROUP LOG_GROUP_DEFAULT
32#include <iprt/types.h>
33#include <iprt/assert.h>
34#include <iprt/mem.h>
35#include <iprt/filesystem.h>
36#include <iprt/string.h>
37#include <iprt/vfs.h>
38#include "internal/filesystem.h"
39
40
41/*******************************************************************************
42* Structures and Typedefs *
43*******************************************************************************/
44
45/*
46 * The filesystem structures are from http://wiki.osdev.org/Ext2 and
47 * http://www.nongnu.org/ext2-doc/ext2.html
48 */
49
50/**
51 * Ext superblock.
52 *
53 * Everything is stored little endian on the disk.
54 */
55#pragma pack(1)
56typedef struct ExtSuperBlock
57{
58 /** Total number of inodes in the filesystem. */
59 uint32_t cInodesTotal;
60 /** Total number of blocks in the filesystem. */
61 uint32_t cBlocksTotal;
62 /** Number of blocks reserved for the super user. */
63 uint32_t cBlocksRsvdForSuperUser;
64 /** Total number of unallocated blocks. */
65 uint32_t cBlocksUnallocated;
66 /** Total number of unallocated inodes. */
67 uint32_t cInodesUnallocated;
68 /** Block number of block containing the superblock. */
69 uint32_t iBlockOfSuperblock;
70 /** Number of bits to shift 1024 to the left to get the block size */
71 uint32_t cBitsShiftLeftBlockSize;
72 /** Number of bits to shift 1024 to the left to get the fragment size */
73 uint32_t cBitsShiftLeftFragmentSize;
74 /** Number of blocks in each block group. */
75 uint32_t cBlocksPerGroup;
76 /** Number of fragments in each block group. */
77 uint32_t cFragmentsPerBlockGroup;
78 /** Number of inodes in each block group. */
79 uint32_t cInodesPerBlockGroup;
80 /** Last mount time. */
81 uint32_t u32LastMountTime;
82 /** Last written time. */
83 uint32_t u32LastWrittenTime;
84 /** Number of times the volume was mounted since the last check. */
85 uint16_t cMountsSinceLastCheck;
86 /** Number of mounts allowed before a consistency check. */
87 uint16_t cMaxMountsUntilCheck;
88 /** Signature to identify a ext2 volume. */
89 uint16_t u16Signature;
90 /** State of the filesystem (clean/errors) */
91 uint16_t u16FilesystemState;
92 /** What to do on an error. */
93 uint16_t u16ActionOnError;
94 /** Minor version field. */
95 uint16_t u16VersionMinor;
96 /** Time of last check. */
97 uint32_t u32LastCheckTime;
98 /** Interval between consistency checks. */
99 uint32_t u32CheckInterval;
100 /** Operating system ID of the filesystem creator. */
101 uint32_t u32OsIdCreator;
102 /** Major version field. */
103 uint32_t u32VersionMajor;
104 /** User ID that is allowed to use reserved blocks. */
105 uint16_t u16UidReservedBlocks;
106 /** Group ID that is allowed to use reserved blocks. */
107 uint16_t u16GidReservedBlocks;
108 /** Reserved fields. */
109 uint8_t abReserved[940];
110} ExtSuperBlock;
111#pragma pack()
112AssertCompileSize(ExtSuperBlock, 1024);
113/** Pointer to an ext super block. */
114typedef ExtSuperBlock *PExtSuperBlock;
115
116/** Ext2 signature. */
117#define RTFILESYSTEM_EXT2_SIGNATURE (0xef53)
118/** Clean filesystem state. */
119#define RTFILESYSTEM_EXT2_STATE_CLEAN (0x0001)
120/** Error filesystem state. */
121#define RTFILESYSTEM_EXT2_STATE_ERRORS (0x0002)
122
123/**
124 * Block group descriptor.
125 */
126#pragma pack(1)
127typedef struct BlockGroupDesc
128{
129 /** Block address of the block bitmap. */
130 uint32_t offBlockBitmap;
131 /** Block address of the inode bitmap. */
132 uint32_t offInodeBitmap;
133 /** Start block address of the inode table. */
134 uint32_t offInodeTable;
135 /** Number of unallocated blocks in group. */
136 uint16_t cBlocksUnallocated;
137 /** Number of unallocated inodes in group. */
138 uint16_t cInodesUnallocated;
139 /** Number of directories in the group. */
140 uint16_t cDirectories;
141 /** Padding. */
142 uint16_t u16Padding;
143 /** Reserved. */
144 uint8_t abReserved[12];
145} BlockGroupDesc;
146#pragma pack()
147AssertCompileSize(BlockGroupDesc, 32);
148/** Pointer to an ext block group descriptor. */
149typedef BlockGroupDesc *PBlockGroupDesc;
150
151/**
152 * Cached block group descriptor data.
153 */
154typedef struct RTFILESYSTEMEXTBLKGRP
155{
156 /** Start offset (in bytes and from the start of the disk). */
157 uint64_t offStart;
158 /** Last offset in the block group (inclusive). */
159 uint64_t offLast;
160 /** Block bitmap - variable in size (depends on the block size
161 * and number of blocks per group). */
162 uint8_t abBlockBitmap[1];
163} RTFILESYSTEMEXTBLKGRP;
164/** Pointer to block group descriptor data. */
165typedef RTFILESYSTEMEXTBLKGRP *PRTFILESYSTEMEXTBLKGRP;
166
167/**
168 * Ext2/3 filesystem data.
169 */
170typedef struct RTFILESYSTEMEXT
171{
172 /** VFS file handle. */
173 RTVFSFILE hVfsFile;
174 /** Block number of the superblock. */
175 uint32_t iSbBlock;
176 /** Size of one block. */
177 size_t cbBlock;
178 /** Number of blocks in one group. */
179 unsigned cBlocksPerGroup;
180 /** Number of blocks groups in the volume. */
181 unsigned cBlockGroups;
182 /** Cached block group descriptor data. */
183 PRTFILESYSTEMEXTBLKGRP pBlkGrpDesc;
184} RTFILESYSTEMEXT;
185/** Pointer to the ext filesystem data. */
186typedef RTFILESYSTEMEXT *PRTFILESYSTEMEXT;
187
188/*******************************************************************************
189* Methods *
190*******************************************************************************/
191
192/**
193 * Loads the block descriptor of the given block group from the medium.
194 *
195 * @returns IPRT status code.
196 * @param pThis EXT filesystem instance data.
197 * @param iBlkGrp Block group number to load.
198 */
199static int rtFsExtLoadBlkGrpDesc(PRTFILESYSTEMEXT pThis, uint32_t iBlkGrp)
200{
201 int rc = VINF_SUCCESS;
202 PRTFILESYSTEMEXTBLKGRP pBlkGrpDesc = pThis->pBlkGrpDesc;
203 uint64_t offRead = (pThis->iSbBlock + 1) * pThis->cbBlock;
204 BlockGroupDesc BlkDesc;
205 size_t cbBlockBitmap;
206
207 cbBlockBitmap = pThis->cBlocksPerGroup / 8;
208 if (pThis->cBlocksPerGroup % 8)
209 cbBlockBitmap++;
210
211 if (!pBlkGrpDesc)
212 {
213 size_t cbBlkDesc = RT_OFFSETOF(RTFILESYSTEMEXTBLKGRP, abBlockBitmap[cbBlockBitmap]);
214 pBlkGrpDesc = (PRTFILESYSTEMEXTBLKGRP)RTMemAllocZ(cbBlkDesc);
215 if (!pBlkGrpDesc)
216 return VERR_NO_MEMORY;
217 }
218
219 rc = RTVfsFileReadAt(pThis->hVfsFile, offRead, &BlkDesc, sizeof(BlkDesc), NULL);
220 if (RT_SUCCESS(rc))
221 {
222 pBlkGrpDesc->offStart = pThis->iSbBlock + (uint64_t)iBlkGrp * pThis->cBlocksPerGroup * pThis->cbBlock;
223 pBlkGrpDesc->offLast = pBlkGrpDesc->offStart + pThis->cBlocksPerGroup * pThis->cbBlock;
224 rc = RTVfsFileReadAt(pThis->hVfsFile, BlkDesc.offBlockBitmap * pThis->cbBlock,
225 &pBlkGrpDesc->abBlockBitmap[0], cbBlockBitmap, NULL);
226 }
227
228 pThis->pBlkGrpDesc = pBlkGrpDesc;
229
230 return rc;
231}
232
233static bool rtFsExtIsBlockRangeInUse(PRTFILESYSTEMEXTBLKGRP pBlkGrpDesc,
234 uint32_t offBlockStart, size_t cBlocks)
235{
236 bool fUsed = false;
237
238 while (cBlocks)
239 {
240 uint32_t idxByte = offBlockStart / 8;
241 uint32_t iBit = offBlockStart % 8;
242
243 if (pBlkGrpDesc->abBlockBitmap[idxByte] & RT_BIT(iBit))
244 {
245 fUsed = true;
246 break;
247 }
248
249 cBlocks--;
250 offBlockStart++;
251 }
252
253 return fUsed;
254}
255
256
257static DECLCALLBACK(int) rtFsExtProbe(RTVFSFILE hVfsFile, uint32_t *puScore)
258{
259 int rc = VINF_SUCCESS;
260 uint64_t cbMedium = 0;
261
262 *puScore = RTFILESYSTEM_MATCH_SCORE_UNSUPPORTED;
263
264 rc = RTVfsFileGetSize(hVfsFile, &cbMedium);
265 if (RT_SUCCESS(rc))
266 {
267 if (cbMedium >= 2*sizeof(ExtSuperBlock))
268 {
269 ExtSuperBlock SuperBlock;
270
271 rc = RTVfsFileReadAt(hVfsFile, 1024, &SuperBlock, sizeof(ExtSuperBlock), NULL);
272 if (RT_SUCCESS(rc))
273 {
274#if defined(RT_BIGENDIAN)
275 /** @todo: Convert to host endianess. */
276#endif
277 if (SuperBlock.u16Signature == RTFILESYSTEM_EXT2_SIGNATURE)
278 *puScore = RTFILESYSTEM_MATCH_SCORE_SUPPORTED;
279 }
280 }
281 }
282
283 return rc;
284}
285
286static DECLCALLBACK(int) rtFsExtInit(void *pvThis, RTVFSFILE hVfsFile)
287{
288 int rc = VINF_SUCCESS;
289 PRTFILESYSTEMEXT pThis = (PRTFILESYSTEMEXT)pvThis;
290 ExtSuperBlock SuperBlock;
291
292 pThis->hVfsFile = hVfsFile;
293 pThis->pBlkGrpDesc = NULL;
294
295 rc = RTVfsFileReadAt(hVfsFile, 1024, &SuperBlock, sizeof(ExtSuperBlock), NULL);
296 if (RT_SUCCESS(rc))
297 {
298#if defined(RT_BIGENDIAN)
299 /** @todo: Convert to host endianess. */
300#endif
301 if (SuperBlock.u16FilesystemState == RTFILESYSTEM_EXT2_STATE_ERRORS)
302 rc = VERR_FILESYSTEM_CORRUPT;
303 else
304 {
305 pThis->iSbBlock = SuperBlock.iBlockOfSuperblock;
306 pThis->cbBlock = 1024 << SuperBlock.cBitsShiftLeftBlockSize;
307 pThis->cBlocksPerGroup = SuperBlock.cBlocksPerGroup;
308 pThis->cBlockGroups = SuperBlock.cBlocksTotal / pThis->cBlocksPerGroup;
309
310 /* Load first block group descriptor. */
311 rc = rtFsExtLoadBlkGrpDesc(pThis, 0);
312 }
313 }
314
315 return rc;
316}
317
318static DECLCALLBACK(void) rtFsExtDestroy(void *pvThis)
319{
320 PRTFILESYSTEMEXT pThis = (PRTFILESYSTEMEXT)pvThis;
321
322 if (pThis->pBlkGrpDesc)
323 RTMemFree(pThis->pBlkGrpDesc);
324}
325
326static DECLCALLBACK(int) rtFsExtOpenRoot(void *pvThis, PRTVFSDIR phVfsDir)
327{
328 NOREF(pvThis);
329 NOREF(phVfsDir);
330 return VERR_NOT_IMPLEMENTED;
331}
332
333static DECLCALLBACK(int) rtFsExtIsRangeInUse(void *pvThis, RTFOFF off, size_t cb,
334 bool *pfUsed)
335{
336 int rc = VINF_SUCCESS;
337 uint64_t offStart = (uint64_t)off;
338 PRTFILESYSTEMEXT pThis = (PRTFILESYSTEMEXT)pvThis;
339
340 *pfUsed = false;
341
342 while (cb > 0)
343 {
344 bool fUsed;
345 uint32_t offBlockStart = (uint32_t)(offStart / pThis->cbBlock);
346 uint32_t iBlockGroup = (offBlockStart - pThis->iSbBlock) / pThis->cBlocksPerGroup;
347 uint32_t offBlockRelStart = offBlockStart - iBlockGroup * pThis->cBlocksPerGroup;
348 size_t cbThis = 0;
349
350 if ( offStart < pThis->pBlkGrpDesc->offStart
351 || offStart > pThis->pBlkGrpDesc->offLast)
352 {
353 /* Load new block descriptor. */
354 rc = rtFsExtLoadBlkGrpDesc(pThis, iBlockGroup);
355 if (RT_FAILURE(rc))
356 break;
357 }
358
359 cbThis = RT_MIN(cb, pThis->pBlkGrpDesc->offLast - offStart + 1);
360 fUsed = rtFsExtIsBlockRangeInUse(pThis->pBlkGrpDesc, offBlockRelStart,
361 cbThis / pThis->cbBlock +
362 (cbThis % pThis->cbBlock ? 1 : 0));
363
364 if (fUsed)
365 {
366 *pfUsed = true;
367 break;
368 }
369
370 cb -= cbThis;
371 offStart += cbThis;
372 }
373
374 return rc;
375}
376
377DECL_HIDDEN_CONST(RTFILESYSTEMDESC) const g_rtFsExt =
378{
379 /** cbFs */
380 sizeof(RTFILESYSTEMEXT),
381 /** VfsOps */
382 {
383 /** uVersion. */
384 RTVFSOPS_VERSION,
385 /** fFeatures */
386 0,
387 /** pszName */
388 "ExtVfsOps",
389 /** pfnDestroy */
390 rtFsExtDestroy,
391 /** pfnOpenRoot */
392 rtFsExtOpenRoot,
393 /** pfnIsRangeInUse */
394 rtFsExtIsRangeInUse,
395 /** uEndMarker */
396 RTVFSOPS_VERSION
397 },
398 /** pfnProbe */
399 rtFsExtProbe,
400 /** pfnInit */
401 rtFsExtInit
402};
403
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