Drop to $VISUAL or $EDITOR to edit a String in rust (via temporary file)

editor.rs

extern crate libc;
use std::io::{File, Open, ReadWrite, TempDir, Command, SeekSet};
use std::io::process::{InheritFd};
use std::os;

pub use self::libc::{
    STDIN_FILENO,
    STDOUT_FILENO,
    STDERR_FILENO
};

fn temporary_editor(contents: String) -> String {
    // setup temporary directory
    let tmpdir = match TempDir::new("tempplace") {
        Ok(dir) => dir,
        Err(e) => panic!("couldn't create temporary directory: {}", e)
    };
    // setup temporary file to write/read
    let tmppath = tmpdir.path().join("something-unique");
    let mut tmpfile = match File::open_mode(&tmppath, Open, ReadWrite) {
        Ok(f) => f,
        Err(e) => panic!("File error: {}", e)
    };
    tmpfile.write_line(contents.as_slice()).ok().expect("Failed to write line to temp file");
    // we now have a temp file, at `tmppath`, that contains `contents`
    // first we need to know which one
    let editor = match os::getenv("VISUAL") {
        Some(val) => val,
        None => {
            match os::getenv("EDITOR") {
                Some(val) => val,
                None => panic!("Neither $VISUAL nor $EDITOR is set.")
            }
        }
    };
    // lets start `editor` and edit the file at `tmppath`
    // first we need to set STDIN, STDOUT, and STDERR to those that theca is
    // currently using so we can display the editor
    let mut editor_command = Command::new(editor);
    editor_command.arg(tmppath.display().to_string());
    editor_command.stdin(InheritFd(libc::STDIN_FILENO));
    editor_command.stdout(InheritFd(libc::STDOUT_FILENO));
    editor_command.stderr(InheritFd(libc::STDERR_FILENO));
    let editor_proc = editor_command.spawn();
    match editor_proc.ok().expect("Couldn't launch editor").wait().is_ok() {
        true => {
            // finished editing, time to read `tmpfile` for the final output
            // seek to start of `tmpfile`
            tmpfile.seek(0, SeekSet).ok().expect("Can't seek to start of temp file");
            tmpfile.read_to_string().unwrap()
        }
        false => panic!("The editor broke")
    }
}

fn main() {
    let test = temporary_editor("this totes works".to_string());
    println!("temp file contained: {}", test);
}