squashfs_utils.c revision 454b989922c7fb8e1411d06ee26ad7c4e6bc2abe 
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#define ERROR(x...)   KLOG_ERROR("squashfs_utils", x)
29
30int squashfs_parse_sb(char *blk_device, struct squashfs_info *info) {
31    int ret = 0;
32    struct squashfs_super_block sb;
33    int data_device;
34
35    data_device = TEMP_FAILURE_RETRY(open(blk_device, O_RDONLY | O_CLOEXEC));
36    if (data_device == -1) {
37        ERROR("Error opening block device (%s)\n", strerror(errno));
38        return -1;
39    }
40
41    if (TEMP_FAILURE_RETRY(read(data_device, &sb, sizeof(sb)))
42            != sizeof(sb)) {
43        ERROR("Error reading superblock\n");
44        ret = -1;
45        goto cleanup;
46    }
47    if (sb.s_magic != SQUASHFS_MAGIC) {
48        ERROR("Not a valid squashfs filesystem\n");
49        ret = -1;
50        goto cleanup;
51    }
52
53    info->block_size = sb.block_size;
54    info->inodes = sb.inodes;
55    info->bytes_used = sb.bytes_used;
56    // by default mksquashfs pads the filesystem to 4K blocks
57    info->bytes_used_4K_padded =
58        sb.bytes_used + (4096 - (sb.bytes_used & (4096 - 1)));
59
60cleanup:
61    close(data_device);
62    return ret;
63}
64