将超级块读入 C 结构

struct super_block {
    unsigned long s_blocksize;
    unsigned long s_blocks_count;
    unsigned long s_free_blocks_count;
    unsigned long s_r_blocks_count;
    unsigned long s_free_inodes_count;
    unsigned long s_first_data_block;
    unsigned long s_log_block_size;
    unsigned long s_log_frag_size;
    unsigned long s_frags_per_group;
    unsigned long s_blocks_per_group;
    unsigned long s_inodes_per_group;
    unsigned long s_mtime;
    unsigned long s_wtime;
    unsigned short s_links_count;
    unsigned short s_errors;
    unsigned short s_flags;
    unsigned short s_raid_stride;
    unsigned short s_mnt_count;
    unsigned short s_max_mnt_count;
    unsigned short s_magic;
    unsigned short s_state;
    unsigned short s_errors_behavior;
    unsigned short s_minor_rev_level;
    unsigned int s_lastcheck;
    unsigned int s_checkinterval;
    unsigned int s_creator_os;
    unsigned int s_rev_level;
    unsigned short s_def_resuid;
    unsigned short s_def_resgid;
    unsigned int s_first_ino;
    unsigned short s_inode_size;
    unsigned short s_block_group_nr;
    unsigned int s_feature_compat;
    unsigned int s_feature_incompat;
    unsigned int s_feature_ro_compat;
    unsigned char s_uuid[16];
    char s_volume_name[16];
    char s_last_mounted[64];
    unsigned int s_algorithm_usage_bitmap;
    unsigned char s_prealloc_blocks;
    unsigned char s_prealloc_dir_blocks;
    unsigned short s_reserved_gdt_blocks;
    unsigned char s_journal_uuid[16];
    unsigned int s_journal_inum;
    unsigned int s_journal_dev;
    unsigned int s_last_orphan;
    unsigned int s_hash_seed[4];
    unsigned char s_def_hash_version;
    unsigned char s_reserved_char_pad;
    unsigned short s_reserved_word_pad;
    unsigned int s_default_mount_opts;
    unsigned int s_first_meta_bg;
    unsigned int s_mkfs_time;
    unsigned char s_jnl_blocks[17];
    unsigned int s_blocks_count_hi;
    unsigned int s_r_blocks_count_hi;
    unsigned int s_free_blocks_count_hi;
    unsigned int s_min_extra_isize;
    unsigned int s_want_extra_isize;
    unsigned int s_flags_hi;
    unsigned short s_raid_stride_width;
    unsigned short s_mmp_update_interval;
    unsigned int s_mmp_block;
    unsigned int s_raid_stripe_width;
    unsigned char s_log_groups_per_flex;
    unsigned char s_checksum_type;
    unsigned char s_encryption_level;
    unsigned char s_reserved_pad;
    unsigned int s_kbytes_written;
    unsigned int s_snapshot_inum;
    unsigned int s_snapshot_id;
    unsigned int s_snapshot_r_blocks_count;
    unsigned int s_snapshot_list;
    unsigned int s_error_count;
    unsigned int s_first_error_time;
    unsigned int s_first_error_ino;
    unsigned int s_first_error_block;
    unsigned char s_first_error_func[32];
    unsigned int s_first_error_line;
    unsigned int s_last_error_time;
    unsigned int s_last_error_ino;
    unsigned int s_last_error_line;
    unsigned int s_last_error_block;
    unsigned char s_last_error_func[32];
    unsigned int s_mount_opts;
    unsigned int s_usr_quota_inum;
    unsigned int s_grp_quota_inum;
    unsigned int s_overhead_blocks;
    unsigned int s_backup_bgs[2];
    unsigned char s_encrypt_algos[4];
    unsigned char s_encrypt_pw_salt[16];
    unsigned int s_lpf_ino;
    unsigned int s_prj_quota_inum;
    unsigned char s_checksum_seed[32];
    unsigned int s_reserved[165];
};

#include<stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include<string.h>
#include <errno.h>

#include "superblock.h"

int main(int argc, char *argv[]) {
    int fd;
    struct super_block sb;

    if (argc != 2) {
        fprintf(stderr, "Usage: %s<device>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    fd = open(argv[1], O_RDONLY);
    if (fd == -1) {
        perror("open");
        exit(EXIT_FAILURE);
    }

    if (read(fd, &sb, sizeof(sb)) != sizeof(sb)) {
        perror("read");
        exit(EXIT_FAILURE);
    }

    close(fd);

    // 在这里可以使用 sb 结构体中的信息

    return 0;
}