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// Copyright 2017 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use std::result;
use std::io;
use std::error;
use std::fmt::{self, Display};
use libc::__errno_location;
/// An error number, retrieved from errno (man 3 errno), set by a libc
/// function that returned an error.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Error(i32);
pub type Result<T> = result::Result<T, Error>;
impl Error {
/// Constructs a new error with the given errno.
pub fn new(e: i32) -> Error {
Error(e)
}
/// Constructs an error from the current errno.
///
/// The result of this only has any meaning just after a libc call that returned a value
/// indicating errno was set.
pub fn last() -> Error {
Error(unsafe { *__errno_location() })
}
/// Gets the errno for this error
pub fn errno(&self) -> i32 {
self.0
}
}
impl From<io::Error> for Error {
fn from(e: io::Error) -> Self {
Error::new(e.raw_os_error().unwrap_or_default())
}
}
impl error::Error for Error {
fn description(&self) -> &str {
"System returned an error code"
}
}
impl Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Error: {}", self.errno())
}
}
/// Returns the last errno as a Result that is always an error.
pub fn errno_result<T>() -> Result<T> {
Err(Error::last())
}
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