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 = (fs->blocksize / sizeof (struct ext2_group_desc)) * i;
43 if (ext2fs_bg_has_super(fs, bg))
44 has_super = 1;
45 ret_blk = (fs->super->s_first_data_block + has_super +
46 (bg * fs->super->s_blocks_per_group));
47 /*
48 * If group_block is not the normal value, we're trying to use
49 * the backup group descriptors and superblock --- so use the
50 * alternate location of the second block group in the
51 * metablock group. Ideally we should be testing each bg
52 * descriptor block individually for correctness, but we don't
53 * have the infrastructure in place to do that.
54 */
55 if (group_block != fs->super->s_first_data_block &&
56 ((ret_blk + fs->super->s_blocks_per_group) <
57 fs->super->s_blocks_count))
58 ret_blk += fs->super->s_blocks_per_group;
59 return ret_blk;
60 }
61
ext2fs_open(const char * name,int flags,int superblock,unsigned int block_size,io_manager manager,ext2_filsys * ret_fs)62 errcode_t ext2fs_open(const char *name, int flags, int superblock,
63 unsigned int block_size, io_manager manager,
64 ext2_filsys *ret_fs)
65 {
66 return ext2fs_open2(name, 0, flags, superblock, block_size,
67 manager, ret_fs);
68 }
69
70 /*
71 * Note: if superblock is non-zero, block-size must also be non-zero.
72 * Superblock and block_size can be zero to use the default size.
73 *
74 * Valid flags for ext2fs_open()
75 *
76 * EXT2_FLAG_RW - Open the filesystem for read/write.
77 * EXT2_FLAG_FORCE - Open the filesystem even if some of the
78 * features aren't supported.
79 * EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
80 */
ext2fs_open2(const char * name,const char * io_options,int flags,int superblock,unsigned int block_size,io_manager manager,ext2_filsys * ret_fs)81 errcode_t ext2fs_open2(const char *name, const char *io_options,
82 int flags, int superblock,
83 unsigned int block_size, io_manager manager,
84 ext2_filsys *ret_fs)
85 {
86 ext2_filsys fs;
87 errcode_t retval;
88 unsigned long i;
89 __u32 features;
90 int j, groups_per_block, blocks_per_group, io_flags;
91 blk_t group_block, blk;
92 char *dest, *cp;
93 struct ext2_group_desc *gdp;
94
95 EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
96
97 retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
98 if (retval)
99 return retval;
100
101 memset(fs, 0, sizeof(struct struct_ext2_filsys));
102 fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
103 fs->flags = flags;
104 /* don't overwrite sb backups unless flag is explicitly cleared */
105 fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
106 fs->umask = 022;
107 retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
108 if (retval)
109 goto cleanup;
110 strcpy(fs->device_name, name);
111 cp = strchr(fs->device_name, '?');
112 if (!io_options && cp) {
113 *cp++ = 0;
114 io_options = cp;
115 }
116
117 io_flags = 0;
118 if (flags & EXT2_FLAG_RW)
119 io_flags |= IO_FLAG_RW;
120 if (flags & EXT2_FLAG_EXCLUSIVE)
121 io_flags |= IO_FLAG_EXCLUSIVE;
122 retval = manager->open(fs->device_name, io_flags, &fs->io);
123 if (retval)
124 goto cleanup;
125 if (io_options &&
126 (retval = io_channel_set_options(fs->io, io_options)))
127 goto cleanup;
128 fs->image_io = fs->io;
129 fs->io->app_data = fs;
130 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
131 if (retval)
132 goto cleanup;
133 if (flags & EXT2_FLAG_IMAGE_FILE) {
134 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
135 &fs->image_header);
136 if (retval)
137 goto cleanup;
138 retval = io_channel_read_blk(fs->io, 0,
139 -(int)sizeof(struct ext2_image_hdr),
140 fs->image_header);
141 if (retval)
142 goto cleanup;
143 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
144 return EXT2_ET_MAGIC_E2IMAGE;
145 superblock = 1;
146 block_size = fs->image_header->fs_blocksize;
147 }
148
149 /*
150 * If the user specifies a specific block # for the
151 * superblock, then he/she must also specify the block size!
152 * Otherwise, read the master superblock located at offset
153 * SUPERBLOCK_OFFSET from the start of the partition.
154 *
155 * Note: we only save a backup copy of the superblock if we
156 * are reading the superblock from the primary superblock location.
157 */
158 if (superblock) {
159 if (!block_size) {
160 retval = EXT2_ET_INVALID_ARGUMENT;
161 goto cleanup;
162 }
163 io_channel_set_blksize(fs->io, block_size);
164 group_block = superblock;
165 fs->orig_super = 0;
166 } else {
167 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
168 superblock = 1;
169 group_block = 0;
170 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
171 if (retval)
172 goto cleanup;
173 }
174 retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
175 fs->super);
176 if (retval)
177 goto cleanup;
178 if (fs->orig_super)
179 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
180
181 #ifdef EXT2FS_ENABLE_SWAPFS
182 if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) ||
183 (fs->flags & EXT2_FLAG_SWAP_BYTES)) {
184 fs->flags |= EXT2_FLAG_SWAP_BYTES;
185
186 ext2fs_swap_super(fs->super);
187 }
188 #endif
189
190 if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
191 retval = EXT2_ET_BAD_MAGIC;
192 goto cleanup;
193 }
194 if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
195 retval = EXT2_ET_REV_TOO_HIGH;
196 goto cleanup;
197 }
198
199 /*
200 * Check for feature set incompatibility
201 */
202 if (!(flags & EXT2_FLAG_FORCE)) {
203 features = fs->super->s_feature_incompat;
204 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
205 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
206 features &= !EXT2_LIB_SOFTSUPP_INCOMPAT;
207 #endif
208 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
209 retval = EXT2_ET_UNSUPP_FEATURE;
210 goto cleanup;
211 }
212
213 features = fs->super->s_feature_ro_compat;
214 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
215 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
216 features &= !EXT2_LIB_SOFTSUPP_RO_COMPAT;
217 #endif
218 if ((flags & EXT2_FLAG_RW) &&
219 (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
220 retval = EXT2_ET_RO_UNSUPP_FEATURE;
221 goto cleanup;
222 }
223
224 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
225 (fs->super->s_feature_incompat &
226 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
227 retval = EXT2_ET_UNSUPP_FEATURE;
228 goto cleanup;
229 }
230 }
231
232 fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
233 if (fs->blocksize == 0) {
234 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
235 goto cleanup;
236 }
237 if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
238 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
239 goto cleanup;
240 }
241 fs->fragsize = EXT2_FRAG_SIZE(fs->super);
242 fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
243 EXT2_INODE_SIZE(fs->super) +
244 EXT2_BLOCK_SIZE(fs->super) - 1) /
245 EXT2_BLOCK_SIZE(fs->super));
246 if (block_size) {
247 if (block_size != fs->blocksize) {
248 retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
249 goto cleanup;
250 }
251 }
252 /*
253 * Set the blocksize to the filesystem's blocksize.
254 */
255 io_channel_set_blksize(fs->io, fs->blocksize);
256
257 /*
258 * If this is an external journal device, don't try to read
259 * the group descriptors, because they're not there.
260 */
261 if (fs->super->s_feature_incompat &
262 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
263 fs->group_desc_count = 0;
264 *ret_fs = fs;
265 return 0;
266 }
267
268 /*
269 * Read group descriptors
270 */
271 blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
272 if (blocks_per_group == 0 ||
273 blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
274 fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) {
275 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
276 goto cleanup;
277 }
278 fs->group_desc_count = ext2fs_div_ceil(fs->super->s_blocks_count -
279 fs->super->s_first_data_block,
280 blocks_per_group);
281 fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
282 EXT2_DESC_PER_BLOCK(fs->super));
283 retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
284 &fs->group_desc);
285 if (retval)
286 goto cleanup;
287 if (!group_block)
288 group_block = fs->super->s_first_data_block;
289 dest = (char *) fs->group_desc;
290 groups_per_block = fs->blocksize / sizeof(struct ext2_group_desc);
291 for (i=0 ; i < fs->desc_blocks; i++) {
292 blk = ext2fs_descriptor_block_loc(fs, group_block, i);
293 retval = io_channel_read_blk(fs->io, blk, 1, dest);
294 if (retval)
295 goto cleanup;
296 #ifdef EXT2FS_ENABLE_SWAPFS
297 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
298 gdp = (struct ext2_group_desc *) dest;
299 for (j=0; j < groups_per_block; j++)
300 ext2fs_swap_group_desc(gdp++);
301 }
302 #endif
303 dest += fs->blocksize;
304 }
305
306 fs->stride = fs->super->s_raid_stride;
307
308 fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
309 *ret_fs = fs;
310 return 0;
311 cleanup:
312 if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
313 *ret_fs = fs;
314 else
315 ext2fs_free(fs);
316 return retval;
317 }
318
319 /*
320 * Set/get the filesystem data I/O channel.
321 *
322 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
323 */
ext2fs_get_data_io(ext2_filsys fs,io_channel * old_io)324 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
325 {
326 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
327 return EXT2_ET_NOT_IMAGE_FILE;
328 if (old_io) {
329 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
330 }
331 return 0;
332 }
333
ext2fs_set_data_io(ext2_filsys fs,io_channel new_io)334 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
335 {
336 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
337 return EXT2_ET_NOT_IMAGE_FILE;
338 fs->io = new_io ? new_io : fs->image_io;
339 return 0;
340 }
341
ext2fs_rewrite_to_io(ext2_filsys fs,io_channel new_io)342 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
343 {
344 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
345 return EXT2_ET_NOT_IMAGE_FILE;
346 fs->io = fs->image_io = new_io;
347 fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
348 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
349 fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
350 return 0;
351 }
352