#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "ext2.h"

#define BASE_OFFSET 1024
#define EXT2_BLOCK_SIZE 1024
#define IMAGE "image.img"

typedef unsigned char bmap;
#define __NBITS (8 * (int) sizeof (bmap))
#define __BMELT(d) ((d) / __NBITS)
#define __BMMASK(d) ((bmap) 1 << ((d) % __NBITS))
#define BM_SET(d, set) ((set[__BMELT (d)] |= __BMMASK (d)))
#define BM_CLR(d, set) ((set[__BMELT (d)] &= ~__BMMASK (d)))
#define BM_ISSET(d, set) ((set[__BMELT (d)] & __BMMASK (d)) != 0)

unsigned int block_size = 0;
#define BLOCK_OFFSET(block) (BASE_OFFSET + (block-1)*block_size)

int main(void)
{
    struct ext2_super_block super;
    struct ext2_group_desc group;
    int fd;

    if ((fd = open(IMAGE, O_RDONLY)) < 0) {
        perror(IMAGE);
        exit(1);
    }

    // read super-block
    lseek(fd, BASE_OFFSET, SEEK_SET);
    read(fd, &super, sizeof(super));
    if (super.s_magic != EXT2_SUPER_MAGIC) {
        fprintf(stderr, "Not a Ext2 filesystem\n");
        exit(1);
    }
    block_size = 1024 << super.s_log_block_size;

    printf("Reading from image file " IMAGE ":\n"
           "Blocks count            : %u\n"
           "First non-reserved inode: %u\n"
           "Inode size              : %u\n",
           super.s_blocks_count,
           super.s_first_ino,
           super.s_inode_size);

    return 0;
}