get MAC addresses of all interfaces on a Linux-ish system, returns a hashmap of (iface_name, mac_addr) without any external dependencies

get_macs.rs

use std::collections::HashMap;
use std::fs;
use std::io::Read;
use std::path::Path;

fn get_macs() -> HashMap<String, String> {
    // cat the /sys/class/net/iface/address to get the MAC
    // based on: https://stackoverflow.com/questions/26346575/how-to-get-mac-address-in-rust
    let net = Path::new("/sys/class/net");
    let entry = fs::read_dir(net).expect("Error");
    let ifaces = entry
        .filter_map(|p| p.ok())
        .map(|p| p.path().file_name().expect("Error").to_os_string())
        .filter_map(|s| s.into_string().ok())
        .collect::<Vec<String>>();

    let macs: Vec<String> = ifaces
        .iter()
        .map(|iface| net.join(iface.as_str()).join("address"))
        .map(|addr_path| fs::File::open(addr_path).unwrap())
        .map(|mut addr_file| {
            let mut macaddr = String::new();
            addr_file.read_to_string(&mut macaddr).unwrap();
            macaddr.trim_end().to_string()
        })
        .collect();
    let mut iface_mac = HashMap::new();
    for (key, value) in ifaces.into_iter().zip(macs) {
        println!("iface {} [{}]", key, value);
        iface_mac.insert(key, value);
    }
    iface_mac
}