Tiny Rust program to parse a knytt.bin file, printing its contents.

knytt.bin.rs

use std::collections::HashMap;
use std::fs::File;
use std::io::Read;

fn main() -> std::io::Result<()> {
    if let Ok(mut file) =
        File::open("E:/Knytt Stories/Test/Drakkan - Training Groundv3rev.knytt.bin")
    {
        let mut files = HashMap::new();

        let mut data: Vec<u8> = Vec::new();
        let bin_size = file.read_to_end(&mut data)?;

        let mut offset = 0;
        let mut root_directory = String::from("");

        //checks for the Knytt Stories header
        if data[0] as char == 'N' && data[1] as char == 'F' {
            offset = 2; //read two chars, move up by two.

            //builds the root directory name until an invalid char is reached.
            while data[offset - 1] as u8 != 0 {
                root_directory.push(data[offset] as char);
                offset += 1;
            }
            //there is a weird int here, just skip it.
            offset += 4;

            //start looping from the file
            while offset < bin_size {
                //there is another header each section we skip
                offset += 2; // skip other header'

                let mut file_name = String::from("");
                //builds the file name until an invalid char is reached.
                while data[offset - 1] as u8 != 0 {
                    let file_character = data[offset] as char;
                    file_name.push(if file_character == '\\' {
                        '/'
                    } else {
                        file_character
                    });
                    offset += 1;
                }

                //assembles the file size from a compressed int.
                let file_size = data[offset] as u32
                    + data[offset + 1] as u32 * 256
                    + data[offset + 2] as u32 * 65536
                    + data[offset + 3] as u32 * 16777216;

                offset += 4; //as if we read an int, move up four bytes.
                files.insert(file_name, file_size);
                offset += file_size as usize; //let's pretend we're actually reading the file data.
            }
            for (k, v) in files.iter() {
                println!(
                    "File Name {root}->{file}{size}",
                    root = root_directory,
                    file = k,
                    size = v
                );
            }
        }
    }
    Ok(())
}