1 /*
2 * openfs.c --- open an ext2 filesystem
3 *
4 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Public
8 * License.
9 * %End-Header%
10 */
11
12 #include <stdio.h>
13 #include <string.h>
14 #if HAVE_UNISTD_H
15 #include <unistd.h>
16 #endif
17 #include <fcntl.h>
18 #include <time.h>
19 #if HAVE_SYS_STAT_H
20 #include <sys/stat.h>
21 #endif
22 #if HAVE_SYS_TYPES_H
23 #include <sys/types.h>
24 #endif
25
26 #include "ext2_fs.h"
27
28
29 #include "ext2fs.h"
30 #include "e2image.h"
31
ext2fs_descriptor_block_loc(ext2_filsys fs,blk_t group_block,dgrp_t i)32 blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
33 {
34 int bg;
35 int has_super = 0;
36 int ret_blk;
37
38 if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
39 (i < fs->super->s_first_meta_bg))
40 return (group_block + i + 1);
41
42 bg = EXT2_DESC_PER_BLOCK(fs->super) * i;
43 if (ext2fs_bg_has_super(fs, bg))
44 has_super = 1;
45 ret_blk = ext2fs_group_first_block(fs, bg) + has_super;
46 /*
47 * If group_block is not the normal value, we're trying to use
48 * the backup group descriptors and superblock --- so use the
49 * alternate location of the second block group in the
50 * metablock group. Ideally we should be testing each bg
51 * descriptor block individually for correctness, but we don't
52 * have the infrastructure in place to do that.
53 */
54 if (group_block != fs->super->s_first_data_block &&
55 ((ret_blk + fs->super->s_blocks_per_group) <
56 fs->super->s_blocks_count))
57 ret_blk += fs->super->s_blocks_per_group;
58 return ret_blk;
59 }
60
ext2fs_open(const char * name,int flags,int superblock,unsigned int block_size,io_manager manager,ext2_filsys * ret_fs)61 errcode_t ext2fs_open(const char *name, int flags, int superblock,
62 unsigned int block_size, io_manager manager,
63 ext2_filsys *ret_fs)
64 {
65 return ext2fs_open2(name, 0, flags, superblock, block_size,
66 manager, ret_fs);
67 }
68
69 /*
70 * Note: if superblock is non-zero, block-size must also be non-zero.
71 * Superblock and block_size can be zero to use the default size.
72 *
73 * Valid flags for ext2fs_open()
74 *
75 * EXT2_FLAG_RW - Open the filesystem for read/write.
76 * EXT2_FLAG_FORCE - Open the filesystem even if some of the
77 * features aren't supported.
78 * EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
79 */
ext2fs_open2(const char * name,const char * io_options,int flags,int superblock,unsigned int block_size,io_manager manager,ext2_filsys * ret_fs)80 errcode_t ext2fs_open2(const char *name, const char *io_options,
81 int flags, int superblock,
82 unsigned int block_size, io_manager manager,
83 ext2_filsys *ret_fs)
84 {
85 ext2_filsys fs;
86 errcode_t retval;
87 unsigned long i, first_meta_bg;
88 __u32 features;
89 int groups_per_block, blocks_per_group, io_flags;
90 blk_t group_block, blk;
91 char *dest, *cp;
92 #ifdef WORDS_BIGENDIAN
93 struct ext2_group_desc *gdp;
94 int j;
95 #endif
96
97 EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
98
99 retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
100 if (retval)
101 return retval;
102
103 memset(fs, 0, sizeof(struct struct_ext2_filsys));
104 fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
105 fs->flags = flags;
106 /* don't overwrite sb backups unless flag is explicitly cleared */
107 fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
108 fs->umask = 022;
109 retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
110 if (retval)
111 goto cleanup;
112 strcpy(fs->device_name, name);
113 cp = strchr(fs->device_name, '?');
114 if (!io_options && cp) {
115 *cp++ = 0;
116 io_options = cp;
117 }
118
119 io_flags = 0;
120 if (flags & EXT2_FLAG_RW)
121 io_flags |= IO_FLAG_RW;
122 if (flags & EXT2_FLAG_EXCLUSIVE)
123 io_flags |= IO_FLAG_EXCLUSIVE;
124 retval = manager->open(fs->device_name, io_flags, &fs->io);
125 if (retval)
126 goto cleanup;
127 if (io_options &&
128 (retval = io_channel_set_options(fs->io, io_options)))
129 goto cleanup;
130 fs->image_io = fs->io;
131 fs->io->app_data = fs;
132 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
133 if (retval)
134 goto cleanup;
135 if (flags & EXT2_FLAG_IMAGE_FILE) {
136 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
137 &fs->image_header);
138 if (retval)
139 goto cleanup;
140 retval = io_channel_read_blk(fs->io, 0,
141 -(int)sizeof(struct ext2_image_hdr),
142 fs->image_header);
143 if (retval)
144 goto cleanup;
145 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
146 return EXT2_ET_MAGIC_E2IMAGE;
147 superblock = 1;
148 block_size = fs->image_header->fs_blocksize;
149 }
150
151 /*
152 * If the user specifies a specific block # for the
153 * superblock, then he/she must also specify the block size!
154 * Otherwise, read the master superblock located at offset
155 * SUPERBLOCK_OFFSET from the start of the partition.
156 *
157 * Note: we only save a backup copy of the superblock if we
158 * are reading the superblock from the primary superblock location.
159 */
160 if (superblock) {
161 if (!block_size) {
162 retval = EXT2_ET_INVALID_ARGUMENT;
163 goto cleanup;
164 }
165 io_channel_set_blksize(fs->io, block_size);
166 group_block = superblock;
167 fs->orig_super = 0;
168 } else {
169 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
170 superblock = 1;
171 group_block = 0;
172 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
173 if (retval)
174 goto cleanup;
175 }
176 retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
177 fs->super);
178 if (retval)
179 goto cleanup;
180 if (fs->orig_super)
181 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
182
183 #ifdef WORDS_BIGENDIAN
184 fs->flags |= EXT2_FLAG_SWAP_BYTES;
185 ext2fs_swap_super(fs->super);
186 #else
187 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
188 retval = EXT2_ET_UNIMPLEMENTED;
189 goto cleanup;
190 }
191 #endif
192
193 if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
194 retval = EXT2_ET_BAD_MAGIC;
195 goto cleanup;
196 }
197 if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
198 retval = EXT2_ET_REV_TOO_HIGH;
199 goto cleanup;
200 }
201
202 /*
203 * Check for feature set incompatibility
204 */
205 if (!(flags & EXT2_FLAG_FORCE)) {
206 features = fs->super->s_feature_incompat;
207 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
208 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
209 features &= !EXT2_LIB_SOFTSUPP_INCOMPAT;
210 #endif
211 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
212 retval = EXT2_ET_UNSUPP_FEATURE;
213 goto cleanup;
214 }
215
216 features = fs->super->s_feature_ro_compat;
217 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
218 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
219 features &= !EXT2_LIB_SOFTSUPP_RO_COMPAT;
220 #endif
221 if ((flags & EXT2_FLAG_RW) &&
222 (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
223 retval = EXT2_ET_RO_UNSUPP_FEATURE;
224 goto cleanup;
225 }
226
227 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
228 (fs->super->s_feature_incompat &
229 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
230 retval = EXT2_ET_UNSUPP_FEATURE;
231 goto cleanup;
232 }
233 }
234
235 if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
236 EXT2_MAX_BLOCK_LOG_SIZE) {
237 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
238 goto cleanup;
239 }
240 fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
241 if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
242 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
243 goto cleanup;
244 }
245 fs->fragsize = EXT2_FRAG_SIZE(fs->super);
246 fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
247 EXT2_INODE_SIZE(fs->super) +
248 EXT2_BLOCK_SIZE(fs->super) - 1) /
249 EXT2_BLOCK_SIZE(fs->super));
250 if (block_size) {
251 if (block_size != fs->blocksize) {
252 retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
253 goto cleanup;
254 }
255 }
256 /*
257 * Set the blocksize to the filesystem's blocksize.
258 */
259 io_channel_set_blksize(fs->io, fs->blocksize);
260
261 /*
262 * If this is an external journal device, don't try to read
263 * the group descriptors, because they're not there.
264 */
265 if (fs->super->s_feature_incompat &
266 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
267 fs->group_desc_count = 0;
268 *ret_fs = fs;
269 return 0;
270 }
271
272 if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
273 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
274 goto cleanup;
275 }
276
277 /*
278 * Read group descriptors
279 */
280 blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
281 if (blocks_per_group == 0 ||
282 blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
283 fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
284 EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
285 fs->super->s_first_data_block >= fs->super->s_blocks_count) {
286 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
287 goto cleanup;
288 }
289 fs->group_desc_count = ext2fs_div_ceil(fs->super->s_blocks_count -
290 fs->super->s_first_data_block,
291 blocks_per_group);
292 if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
293 fs->super->s_inodes_count) {
294 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
295 goto cleanup;
296 }
297 fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
298 EXT2_DESC_PER_BLOCK(fs->super));
299 retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
300 &fs->group_desc);
301 if (retval)
302 goto cleanup;
303 if (!group_block)
304 group_block = fs->super->s_first_data_block;
305 dest = (char *) fs->group_desc;
306 groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
307 if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
308 first_meta_bg = fs->super->s_first_meta_bg;
309 else
310 first_meta_bg = fs->desc_blocks;
311 if (first_meta_bg) {
312 retval = io_channel_read_blk(fs->io, group_block+1,
313 first_meta_bg, dest);
314 if (retval)
315 goto cleanup;
316 #ifdef WORDS_BIGENDIAN
317 gdp = (struct ext2_group_desc *) dest;
318 for (j=0; j < groups_per_block*first_meta_bg; j++)
319 ext2fs_swap_group_desc(gdp++);
320 #endif
321 dest += fs->blocksize*first_meta_bg;
322 }
323 for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
324 blk = ext2fs_descriptor_block_loc(fs, group_block, i);
325 retval = io_channel_read_blk(fs->io, blk, 1, dest);
326 if (retval)
327 goto cleanup;
328 #ifdef WORDS_BIGENDIAN
329 gdp = (struct ext2_group_desc *) dest;
330 for (j=0; j < groups_per_block; j++)
331 ext2fs_swap_group_desc(gdp++);
332 #endif
333 dest += fs->blocksize;
334 }
335
336 fs->stride = fs->super->s_raid_stride;
337
338 /*
339 * If recovery is from backup superblock, Clear _UNININT flags &
340 * reset bg_itable_unused to zero
341 */
342 if (superblock > 1 && EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
343 EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
344 struct ext2_group_desc *gd;
345 for (i = 0, gd = fs->group_desc; i < fs->group_desc_count;
346 i++, gd++) {
347 gd->bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
348 gd->bg_flags &= ~EXT2_BG_INODE_UNINIT;
349 gd->bg_itable_unused = 0;
350 }
351 ext2fs_mark_super_dirty(fs);
352 }
353
354 fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
355 *ret_fs = fs;
356 return 0;
357 cleanup:
358 if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
359 *ret_fs = fs;
360 else
361 ext2fs_free(fs);
362 return retval;
363 }
364
365 /*
366 * Set/get the filesystem data I/O channel.
367 *
368 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
369 */
ext2fs_get_data_io(ext2_filsys fs,io_channel * old_io)370 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
371 {
372 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
373 return EXT2_ET_NOT_IMAGE_FILE;
374 if (old_io) {
375 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
376 }
377 return 0;
378 }
379
ext2fs_set_data_io(ext2_filsys fs,io_channel new_io)380 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
381 {
382 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
383 return EXT2_ET_NOT_IMAGE_FILE;
384 fs->io = new_io ? new_io : fs->image_io;
385 return 0;
386 }
387
ext2fs_rewrite_to_io(ext2_filsys fs,io_channel new_io)388 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
389 {
390 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
391 return EXT2_ET_NOT_IMAGE_FILE;
392 fs->io = fs->image_io = new_io;
393 fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
394 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
395 fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
396 return 0;
397 }
398