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use std::convert;
use std::env;
use std::error;
use std::fmt;
use std::fs;
use std::io;
use std::io::Read;
#[derive(Debug)]
pub enum EnvFileError {
EnvVarError(env::VarError),
Io(io::Error),
}
impl convert::From<env::VarError> for EnvFileError {
fn from(err: env::VarError) -> EnvFileError {
EnvFileError::EnvVarError(err)
}
}
impl convert::From<io::Error> for EnvFileError {
fn from(err: io::Error) -> EnvFileError {
EnvFileError::Io(err)
}
}
impl fmt::Display for EnvFileError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
EnvFileError::EnvVarError(ref err) => write!(f, "environment variable error: {}", err),
EnvFileError::Io(ref err) => write!(f, "i/o error: {}", err),
}
}
}
impl error::Error for EnvFileError {
fn description(&self) -> &str {
match *self {
EnvFileError::EnvVarError(ref err) => err.description(),
EnvFileError::Io(ref err) => err.description(),
}
}
fn cause(&self) -> Option<&error::Error> {
match *self {
EnvFileError::EnvVarError(ref err) => Some(err),
EnvFileError::Io(ref err) => Some(err),
}
}
}
pub fn read(env_name: &str) -> Result<String, EnvFileError> {
let filename = try!(env::var(env_name));
let mut file = try!(fs::File::open(filename));
let mut retval = String::new();
try!(file.read_to_string(&mut retval));
Ok(retval)
}