squashfs_utils.c revision d640b023a6272852551550df15c2de01c335d43d 
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/klog.h>
20#include <errno.h>
21#include <fcntl.h>
22#include <stdlib.h>
23#include <string.h>
24#include <unistd.h>
25
26#include "squashfs_fs.h"
27
28#ifdef SQUASHFS_NO_KLOG
29#include <stdio.h>
30#define ERROR(x...)   fprintf(stderr, x)
31#else
32#define ERROR(x...)   KLOG_ERROR("squashfs_utils", x)
33#endif
34
35size_t squashfs_get_sb_size()
36{
37    return sizeof(struct squashfs_super_block);
38}
39
40int squashfs_parse_sb_buffer(const void *buf, struct squashfs_info *info)
41{
42    const struct squashfs_super_block *sb =
43        (const struct squashfs_super_block *)buf;
44
45    if (sb->s_magic != SQUASHFS_MAGIC) {
46        return -1;
47    }
48
49    info->block_size = sb->block_size;
50    info->inodes = sb->inodes;
51    info->bytes_used = sb->bytes_used;
52    // by default mksquashfs pads the filesystem to 4K blocks
53    info->bytes_used_4K_padded =
54        sb->bytes_used + (4096 - (sb->bytes_used & (4096 - 1)));
55
56    return 0;
57}
58
59int squashfs_parse_sb(const char *blk_device, struct squashfs_info *info)
60{
61    int ret = 0;
62    struct squashfs_super_block sb;
63    int data_device;
64
65    data_device = TEMP_FAILURE_RETRY(open(blk_device, O_RDONLY | O_CLOEXEC));
66    if (data_device == -1) {
67        ERROR("Error opening block device (%s)\n", strerror(errno));
68        return -1;
69    }
70
71    if (TEMP_FAILURE_RETRY(read(data_device, &sb, sizeof(sb)))
72            != sizeof(sb)) {
73        ERROR("Error reading superblock\n");
74        ret = -1;
75        goto cleanup;
76    }
77
78    if (squashfs_parse_sb_buffer(&sb, info) == -1) {
79        ERROR("Not a valid squashfs filesystem\n");
80        ret = -1;
81        goto cleanup;
82    }
83
84cleanup:
85    close(data_device);
86    return ret;
87}
88