1 /*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "ext4_utils/ext4_utils.h"
18
19 #include <fcntl.h>
20 #include <inttypes.h>
21 #include <stddef.h>
22 #include <string.h>
23 #include <sys/stat.h>
24 #include <sys/types.h>
25
26 #ifdef _WIN32
27 #include <winsock2.h>
28 #else
29 #include <arpa/inet.h>
30 #include <sys/ioctl.h>
31 #endif
32
33 #if defined(__linux__)
34 #include <linux/fs.h>
35 #elif defined(__APPLE__) && defined(__MACH__)
36 #include <sys/disk.h>
37 #endif
38
39 #include "helpers.h"
40
41 int force = 0;
42 struct fs_info info;
43 struct fs_aux_info aux_info;
44
45 jmp_buf setjmp_env;
46
47 /* returns 1 if a is a power of b */
is_power_of(int a,int b)48 static int is_power_of(int a, int b) {
49 while (a > b) {
50 if (a % b) return 0;
51 a /= b;
52 }
53
54 return (a == b) ? 1 : 0;
55 }
56
bitmap_get_bit(u8 * bitmap,u32 bit)57 int bitmap_get_bit(u8* bitmap, u32 bit) {
58 if (bitmap[bit / 8] & (1 << (bit % 8))) return 1;
59
60 return 0;
61 }
62
bitmap_clear_bit(u8 * bitmap,u32 bit)63 void bitmap_clear_bit(u8* bitmap, u32 bit) {
64 bitmap[bit / 8] &= ~(1 << (bit % 8));
65
66 return;
67 }
68
69 /* Returns 1 if the bg contains a backup superblock. On filesystems with
70 the sparse_super feature, only block groups 0, 1, and powers of 3, 5,
71 and 7 have backup superblocks. Otherwise, all block groups have backup
72 superblocks */
ext4_bg_has_super_block(int bg)73 int ext4_bg_has_super_block(int bg) {
74 /* Without sparse_super, every block group has a superblock */
75 if (!(info.feat_ro_compat & EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) return 1;
76
77 if (bg == 0 || bg == 1) return 1;
78
79 if (is_power_of(bg, 3) || is_power_of(bg, 5) || is_power_of(bg, 7)) return 1;
80
81 return 0;
82 }
83
84 /* Function to read the primary superblock */
read_sb(int fd,struct ext4_super_block * sb)85 void read_sb(int fd, struct ext4_super_block* sb) {
86 if (lseek(fd, 1024, SEEK_SET) < 0) critical_error_errno("failed to seek to superblock");
87
88 ssize_t ret = read(fd, sb, sizeof(*sb));
89 if (ret < 0) critical_error_errno("failed to read superblock");
90 if (ret != sizeof(*sb)) critical_error("failed to read all of superblock");
91 }
92
93 /* Compute the rest of the parameters of the filesystem from the basic info */
ext4_create_fs_aux_info()94 void ext4_create_fs_aux_info() {
95 aux_info.first_data_block = (info.block_size > 1024) ? 0 : 1;
96 aux_info.len_blocks = info.len / info.block_size;
97 aux_info.inode_table_blocks =
98 DIV_ROUND_UP(info.inodes_per_group * info.inode_size, info.block_size);
99 aux_info.groups =
100 DIV_ROUND_UP(aux_info.len_blocks - aux_info.first_data_block, info.blocks_per_group);
101 aux_info.blocks_per_ind = info.block_size / sizeof(u32);
102 aux_info.blocks_per_dind = aux_info.blocks_per_ind * aux_info.blocks_per_ind;
103 aux_info.blocks_per_tind = aux_info.blocks_per_dind * aux_info.blocks_per_dind;
104
105 aux_info.bg_desc_blocks =
106 DIV_ROUND_UP(aux_info.groups * (size_t)info.bg_desc_size, info.block_size);
107
108 aux_info.default_i_flags = EXT4_NOATIME_FL;
109
110 u32 last_group_size = aux_info.len_blocks == info.blocks_per_group
111 ? aux_info.len_blocks
112 : aux_info.len_blocks % info.blocks_per_group;
113 u32 last_header_size = 2 + aux_info.inode_table_blocks;
114 if (ext4_bg_has_super_block((int)aux_info.groups - 1))
115 last_header_size += 1 + aux_info.bg_desc_blocks + info.bg_desc_reserve_blocks;
116 if (aux_info.groups <= 1 && last_group_size < last_header_size) {
117 critical_error("filesystem size too small");
118 }
119 if (last_group_size > 0 && last_group_size < last_header_size) {
120 aux_info.groups--;
121 aux_info.len_blocks -= last_group_size;
122 }
123
124 /* A zero-filled superblock to be written firstly to the block
125 * device to mark the file-system as invalid
126 */
127 aux_info.sb_zero = (struct ext4_super_block*)calloc(1, info.block_size);
128 if (!aux_info.sb_zero) critical_error_errno("calloc");
129
130 /* The write_data* functions expect only block aligned calls.
131 * This is not an issue, except when we write out the super
132 * block on a system with a block size > 1K. So, we need to
133 * deal with that here.
134 */
135 aux_info.sb_block = (struct ext4_super_block*)calloc(1, info.block_size);
136 if (!aux_info.sb_block) critical_error_errno("calloc");
137
138 if (info.block_size > 1024)
139 aux_info.sb = (struct ext4_super_block*)((char*)aux_info.sb_block + 1024);
140 else
141 aux_info.sb = aux_info.sb_block;
142
143 /* Alloc an array to hold the pointers to the backup superblocks */
144 aux_info.backup_sb =
145 (struct ext4_super_block**)calloc(aux_info.groups, sizeof(struct ext4_super_block*));
146
147 if (!aux_info.sb) critical_error_errno("calloc");
148
149 aux_info.bg_desc =
150 (struct ext2_group_desc*)calloc(aux_info.groups, sizeof(struct ext2_group_desc));
151 if (!aux_info.bg_desc) critical_error_errno("calloc");
152 aux_info.xattrs = NULL;
153 }
154
ext4_free_fs_aux_info()155 void ext4_free_fs_aux_info() {
156 unsigned int i;
157
158 for (i = 0; i < aux_info.groups; i++) {
159 if (aux_info.backup_sb[i]) free(aux_info.backup_sb[i]);
160 }
161 free(aux_info.sb_block);
162 free(aux_info.sb_zero);
163 free(aux_info.bg_desc);
164 }
165
ext4_parse_sb_info(struct ext4_super_block * sb)166 void ext4_parse_sb_info(struct ext4_super_block* sb) {
167 if (sb->s_magic != EXT4_SUPER_MAGIC) error("superblock magic incorrect");
168
169 if ((sb->s_state & EXT4_VALID_FS) != EXT4_VALID_FS) error("filesystem state not valid");
170
171 ext4_parse_sb(sb, &info);
172
173 ext4_create_fs_aux_info();
174
175 memcpy(aux_info.sb, sb, sizeof(*sb));
176
177 if (aux_info.first_data_block != sb->s_first_data_block)
178 critical_error("first data block does not match");
179 }
180
get_block_device_size(int fd)181 u64 get_block_device_size(int fd) {
182 u64 size = 0;
183 int ret;
184
185 #if defined(__linux__)
186 ret = ioctl(fd, BLKGETSIZE64, &size);
187 #elif defined(__APPLE__) && defined(__MACH__)
188 ret = ioctl(fd, DKIOCGETBLOCKCOUNT, &size);
189 #else
190 close(fd);
191 return 0;
192 #endif
193
194 if (ret) return 0;
195
196 return size;
197 }
198
is_block_device_fd(int fd)199 int is_block_device_fd(int fd __attribute__((unused))) {
200 #ifdef _WIN32
201 return 0;
202 #else
203 struct stat st;
204 int ret = fstat(fd, &st);
205 if (ret < 0) return 0;
206
207 return S_ISBLK(st.st_mode);
208 #endif
209 }
210
get_file_size(int fd)211 u64 get_file_size(int fd) {
212 struct stat buf;
213 int ret;
214 u64 reserve_len = 0;
215 s64 computed_size;
216
217 ret = fstat(fd, &buf);
218 if (ret) return 0;
219
220 if (info.len < 0) reserve_len = -info.len;
221
222 if (S_ISREG(buf.st_mode))
223 computed_size = buf.st_size - reserve_len;
224 else if (S_ISBLK(buf.st_mode))
225 computed_size = get_block_device_size(fd) - reserve_len;
226 else
227 computed_size = 0;
228
229 if (computed_size < 0) {
230 warn("Computed filesystem size less than 0");
231 computed_size = 0;
232 }
233
234 return computed_size;
235 }
236
read_block_group_descriptors(int fd)237 static void read_block_group_descriptors(int fd) {
238 size_t size = info.block_size * (size_t)aux_info.bg_desc_blocks;
239 void* buf = malloc(size);
240 ssize_t ret;
241
242 if (!buf) critical_error("failed to alloc buffer");
243
244 ret = read(fd, buf, size);
245 if (ret < 0) {
246 free(buf);
247 critical_error_errno("failed to read block group descriptors");
248 }
249 if (ret != size) {
250 free(buf);
251 critical_error("failed to read all the block group descriptors");
252 }
253 const struct ext4_group_desc* gdp = (const struct ext4_group_desc*)buf;
254 bool extended = (info.bg_desc_size >= EXT4_MIN_DESC_SIZE_64BIT);
255 for (size_t i = 0; i < aux_info.groups; i++) {
256 aux_info.bg_desc[i].bg_block_bitmap =
257 (extended ? (u64)gdp->bg_block_bitmap_hi << 32 : 0) | gdp->bg_block_bitmap_lo;
258 aux_info.bg_desc[i].bg_inode_bitmap =
259 (extended ? (u64)gdp->bg_inode_bitmap_hi << 32 : 0) | gdp->bg_inode_bitmap_lo;
260 aux_info.bg_desc[i].bg_inode_table =
261 (extended ? (u64)gdp->bg_inode_table_hi << 32 : 0) | gdp->bg_inode_table_lo;
262 aux_info.bg_desc[i].bg_free_blocks_count =
263 (extended ? (u32)gdp->bg_free_blocks_count_hi << 16 : 0) |
264 gdp->bg_free_blocks_count_lo;
265 aux_info.bg_desc[i].bg_free_inodes_count =
266 (extended ? (u32)gdp->bg_free_inodes_count_hi << 16 : 0) |
267 gdp->bg_free_inodes_count_lo;
268 aux_info.bg_desc[i].bg_used_dirs_count =
269 (extended ? (u32)gdp->bg_used_dirs_count_hi << 16 : 0) | gdp->bg_used_dirs_count_lo;
270 aux_info.bg_desc[i].bg_flags = gdp->bg_flags;
271 gdp = (const struct ext4_group_desc*)((u8*)gdp + info.bg_desc_size);
272 }
273 free(buf);
274 }
275
read_ext(int fd,int verbose)276 int read_ext(int fd, int verbose) {
277 off_t ret;
278 struct ext4_super_block sb;
279
280 read_sb(fd, &sb);
281
282 ext4_parse_sb_info(&sb);
283
284 ret = lseek(fd, info.len, SEEK_SET);
285 if (ret < 0) critical_error_errno("failed to seek to end of input image");
286
287 ret = lseek(fd, info.block_size * (aux_info.first_data_block + 1), SEEK_SET);
288 if (ret < 0) critical_error_errno("failed to seek to block group descriptors");
289
290 read_block_group_descriptors(fd);
291
292 if (verbose) {
293 printf("Found filesystem with parameters:\n");
294 printf(" Size: %" PRIu64 "\n", info.len);
295 printf(" Block size: %d\n", info.block_size);
296 printf(" Blocks per group: %d\n", info.blocks_per_group);
297 printf(" Inodes per group: %d\n", info.inodes_per_group);
298 printf(" Inode size: %d\n", info.inode_size);
299 printf(" Label: %s\n", info.label);
300 printf(" Blocks: %" PRIext4u64 "\n", aux_info.len_blocks);
301 printf(" Block groups: %d\n", aux_info.groups);
302 printf(" Reserved block group size: %d\n", info.bg_desc_reserve_blocks);
303 printf(" Block group descriptor size: %d\n", info.bg_desc_size);
304 printf(" Used %d/%d inodes and %d/%d blocks\n",
305 aux_info.sb->s_inodes_count - aux_info.sb->s_free_inodes_count,
306 aux_info.sb->s_inodes_count,
307 aux_info.sb->s_blocks_count_lo - aux_info.sb->s_free_blocks_count_lo,
308 aux_info.sb->s_blocks_count_lo);
309 }
310
311 return 0;
312 }
313