A `cat` implemenation written in Rust using output buffering and stdio locking

cat.rs

#[macro_use]
extern crate error_chain;

use std::env;
use std::fs::File;
use std::io::{self, BufReader, Read, Write};

pub const BUFFER_CAPACITY: usize = 64 * 1024;

error_chain! {
    foreign_links {
        Io(std::io::Error);
    }
}

fn run() -> Result<()> {
    let stdout = io::stdout();
    let mut locked = stdout.lock();

    let mut buffer = [0u8; BUFFER_CAPACITY];

    if let Some(path) = env::args().nth(1) {
        let input = File::open(path)?;
        let mut buffered = BufReader::new(input);

        loop {
            let bytes_read = buffered.read(&mut buffer);
            if bytes_read.unwrap() == 0 {
                break;
            }
            locked.write_all(&buffer)?;
        }
    }
    Ok(())
}

quick_main!(run);