lab_fat12

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>

typedef struct fat_BS
{
    unsigned char 		bootjmp[3];
    unsigned char 		oem_name[8];
    unsigned short 	    bytes_per_sector;
    unsigned char		sectors_per_cluster;
    unsigned short		reserved_sector_count;
    unsigned char		table_count;
    unsigned short		root_entry_count;
    unsigned short		total_sectors_16;
    unsigned char		media_type;
    unsigned short		table_size_16;
    unsigned short		sectors_per_track;
    unsigned short		head_side_count;
    unsigned int 		hidden_sector_count;
    unsigned int 		total_sectors_32;

}__attribute__((packed)) fat_BS_t;

typedef struct boot_sec{
    unsigned char bios_int;
    unsigned char not_used;
    unsigned char extended_boot;
    unsigned int volume_number;
    unsigned char volume_label[11];
    unsigned char file_system[8];
    unsigned char not_used2[448];
    unsigned char signature_value[2];
}__attribute__((packed)) boot_sec_struct;

typedef struct root_dir{
    unsigned char filename_first_char;
    unsigned char filename[10];
    unsigned char file_attributes;
    unsigned char reserved;
    unsigned char file_creation_time;
    unsigned short creation_time;
    unsigned short creation_date;
    unsigned short access_date;
    unsigned short high_order_bytes;
    unsigned short modified_time;
    unsigned short modified_date;
    unsigned short low_order_bytes;
    unsigned int file_size;
}__attribute__((packed)) root_dir_struct;

int main() {
    struct fat_BS *test = malloc(sizeof(fat_BS_t));
    struct boot_sec *test2 = malloc(sizeof(boot_sec_struct));

    FILE *testing = fopen("fat12_c1.bin", "rb");

    fread(test, sizeof(fat_BS_t), 1, testing);
    fread(test2, sizeof(boot_sec_struct), 1, testing);

    int fat_size = test->table_size_16 * test->bytes_per_sector;

    unsigned char *test3 = malloc(fat_size);
    unsigned char *test4 = malloc(fat_size);

    int reserved_size = test->reserved_sector_count * test->bytes_per_sector;

    fseek(testing, reserved_size, SEEK_SET);
    fread(test3, fat_size, 1, testing);
    fread(test4, fat_size, 1, testing);

    struct root_dir *array_of_root = malloc(sizeof(root_dir_struct)*test->root_entry_count);
    fseek(testing, reserved_size + fat_size * (unsigned int) (test->table_count), SEEK_SET);
    for(int x = 0; x < test->root_entry_count; x++){
        fread((array_of_root+x), sizeof(root_dir_struct), 1, testing);
    }

    int curr_pos = ftell(testing);

    unsigned char *file_from_bin;

    for(int x = 0; x < test->root_entry_count; x++){
        fseek(testing, curr_pos, SEEK_SET);
        fseek(testing, (array_of_root->low_order_bytes -2 ) * test->bytes_per_sector, SEEK_CUR);
        file_from_bin = malloc(array_of_root->file_size+10);
        fread(file_from_bin, array_of_root->file_size, 1, testing);
        printf("%d", x);
    }

    fclose(testing);
    free(test);
    free(test2);
    free(test3);
    free(test4);
    free(file_from_bin);
    return 0;
}