reading a file in rust using buffered reader

gistfile1.txt

use std::fs::File;
use std::io;
use std::io::prelude::*;
use std::io::BufReader;

fn main() {
   let s = match read_as_string("<path/to/file>".to_string()) {
       Ok(content) => content,
       Err(e) => format!("{:?}", e),
   };
   println!("{}", s);
}

fn read_as_string(n: String) -> Result<String, io::Error> {
    let mut s = String::new();
    let f = File::open(n)?;
    let mut r = BufReader::new(f);
    while match r.read_line(&mut s) {
        // 0 means eof
        Ok(0) => false,
        // error
        Err(e) => return Err(e), 
        // read was a success
        _ => true,
    }{}
    Ok(s)
}