use std::io::{Read, Seek, SeekFrom};
use std::fs::File;
use std::path::Path;

use std::mem;

fn read_four_bytes<P: AsRef<Path>>(path: P) -> [u8; 4] {
    let mut file = File::open(path).expect("File IO Failure");
    let mut value = [0u8; 4];
    file.read_exact(&mut value).expect("Unable to read 4 bytes");
    value
}

fn read_float_at_40<P: AsRef<Path>>(path: P) -> f32 {
    let mut file = File::open(path).expect("File IO Failure");
    let mut value = [0u8; 4];
    file.seek(SeekFrom::Start(40)).expect("Unable to seek to 40 bytes");
    file.read_exact(&mut value).expect("Unable to read 4 bytes");
    unsafe { mem::transmute::<[u8; 4], f32>(value) }
}

fn main() {
    let header = read_four_bytes("/proc/self/exe");
    assert_eq!(header, [0x7F, b'E', b'L', b'F']);
    println!("{:?}", header);

    let random_float = read_float_at_40("/proc/self/exe");
    println!("{:?}", random_float);
}