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/* SPDX-License-Identifier: GPL-3.0-or-later */
/*
* read_super.c
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*/
#include "config.h"
#include "squashfs.h"
#include "util.h"
#include <endian.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
int sqfs_super_read(sqfs_super_t *super, int fd)
{
size_t block_size = 0;
sqfs_super_t temp;
int i;
if (read_data_at("reading super block", 0, fd, &temp, sizeof(temp)))
return -1;
temp.magic = le32toh(temp.magic);
temp.inode_count = le32toh(temp.inode_count);
temp.modification_time = le32toh(temp.modification_time);
temp.block_size = le32toh(temp.block_size);
temp.fragment_entry_count = le32toh(temp.fragment_entry_count);
temp.compression_id = le16toh(temp.compression_id);
temp.block_log = le16toh(temp.block_log);
temp.flags = le16toh(temp.flags);
temp.id_count = le16toh(temp.id_count);
temp.version_major = le16toh(temp.version_major);
temp.version_minor = le16toh(temp.version_minor);
temp.root_inode_ref = le64toh(temp.root_inode_ref);
temp.bytes_used = le64toh(temp.bytes_used);
temp.id_table_start = le64toh(temp.id_table_start);
temp.xattr_id_table_start = le64toh(temp.xattr_id_table_start);
temp.inode_table_start = le64toh(temp.inode_table_start);
temp.directory_table_start = le64toh(temp.directory_table_start);
temp.fragment_table_start = le64toh(temp.fragment_table_start);
temp.export_table_start = le64toh(temp.export_table_start);
if (temp.magic != SQFS_MAGIC) {
fputs("Magic number missing. Not a squashfs image.\n", stderr);
return -1;
}
if ((temp.version_major != SQFS_VERSION_MAJOR) ||
(temp.version_minor != SQFS_VERSION_MINOR)) {
fprintf(stderr,
"The squashfs image uses squashfs version %d.%d\n"
"This tool currently only supports version %d.%d.\n",
temp.version_major, temp.version_minor,
SQFS_VERSION_MAJOR, SQFS_VERSION_MINOR);
return -1;
}
if ((temp.block_size - 1) & temp.block_size) {
fputs("Block size in image is not a power of 2!\n", stderr);
return -1;
}
if (temp.block_size < 4096 || temp.block_size >= (1 << 20)) {
fputs("Block size in iamge not between 4k and 1M\n", stderr);
return -1;
}
if (temp.block_log < 12 || temp.block_log > 20)
goto fail_block_log;
block_size = 1;
for (i = 0; i < temp.block_log; ++i)
block_size <<= 1;
if (temp.block_size != block_size)
goto fail_block_log;
if (temp.compression_id < SQFS_COMP_MIN ||
temp.compression_id > SQFS_COMP_MAX) {
fputs("Image uses an unsupported compressor\n", stderr);
return -1;
}
if (temp.id_count == 0) {
fputs("ID table in squashfs image is empty.\n", stderr);
return -1;
}
memcpy(super, &temp, sizeof(temp));
return 0;
fail_block_log:
fputs("Mismatch between block size and block log\n", stderr);
fputs("Filesystem probably currupted.\n", stderr);
return -1;
}
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