rust image to data uri

data_uri.rs

extern crate rustc_serialize;
extern crate regex;

use rustc_serialize::base64::{ToBase64, MIME};
use rustc_serialize::hex::{ToHex};
use std::path::Path;
use std::env;
use std::fs::File;
use std::io::Read;
use regex::Regex;

fn main() {

  if let Some(path) = env::args().nth(1) {

    let path = Path::new(&path);

    let mut file = File::open(&path).unwrap();
    let mut buffer = Vec::new();

    let _out = file.read_to_end(&mut buffer);

    let b64 = buffer.to_base64(MIME);
    let hex = buffer.to_hex();

    println!("data:image/{};base64,{}", get_type(&hex), b64);

  } else {
    panic!("You must provide a file path");
  }

}

fn get_type(file: &str) -> &str {
  if Regex::new(r"^ffd8ffe0").unwrap().is_match(file) { "jpg" }
  else if Regex::new(r"^89504e47").unwrap().is_match(file){ "png" }
  else if Regex::new(r"^47494638").unwrap().is_match(file){ "gif" }
  else { panic!("invalid file") }
}

my first experiment with rust... convert image into data uri