1 /*
2 * Copyright (C) 2015 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 "squashfs_utils.h"
18
19 #include <cutils/fs.h>
20 #include <cutils/klog.h>
21 #include <errno.h>
22 #include <fcntl.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <unistd.h>
26
27 #include "squashfs_fs.h"
28
29 #ifdef SQUASHFS_NO_KLOG
30 #include <stdio.h>
31 #define ERROR(x...) fprintf(stderr, x)
32 #else
33 #define ERROR(x...) KLOG_ERROR("squashfs_utils", x)
34 #endif
35
squashfs_get_sb_size()36 size_t squashfs_get_sb_size()
37 {
38 return sizeof(struct squashfs_super_block);
39 }
40
squashfs_parse_sb_buffer(const void * buf,struct squashfs_info * info)41 int squashfs_parse_sb_buffer(const void *buf, struct squashfs_info *info)
42 {
43 const struct squashfs_super_block *sb =
44 (const struct squashfs_super_block *)buf;
45
46 if (sb->s_magic != SQUASHFS_MAGIC) {
47 return -1;
48 }
49
50 info->block_size = sb->block_size;
51 info->inodes = sb->inodes;
52 info->bytes_used = sb->bytes_used;
53 // by default mksquashfs pads the filesystem to 4K blocks
54 info->bytes_used_4K_padded =
55 sb->bytes_used + (4096 - (sb->bytes_used & (4096 - 1)));
56
57 return 0;
58 }
59
squashfs_parse_sb(const char * blk_device,struct squashfs_info * info)60 int squashfs_parse_sb(const char *blk_device, struct squashfs_info *info)
61 {
62 int ret = 0;
63 struct squashfs_super_block sb;
64 int data_device;
65
66 data_device = TEMP_FAILURE_RETRY(open(blk_device, O_RDONLY | O_CLOEXEC));
67 if (data_device == -1) {
68 ERROR("Error opening block device (%s)\n", strerror(errno));
69 return -1;
70 }
71
72 if (TEMP_FAILURE_RETRY(read(data_device, &sb, sizeof(sb)))
73 != sizeof(sb)) {
74 ERROR("Error reading superblock\n");
75 ret = -1;
76 goto cleanup;
77 }
78
79 if (squashfs_parse_sb_buffer(&sb, info) == -1) {
80 ERROR("Not a valid squashfs filesystem\n");
81 ret = -1;
82 goto cleanup;
83 }
84
85 cleanup:
86 close(data_device);
87 return ret;
88 }
89