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//! Cross-platform interface to the `errno` variable.
//!
//! # Examples
//! ```
//! use errno::{Errno, errno, set_errno};
//!
//! // Get the current value of errno
//! let e = errno();
//!
//! // Set the current value of errno
//! set_errno(e);
//!
//! // Extract the error code as an i32
//! let code = e.0;
//!
//! // Display a human-friendly error message
//! println!("Error {}: {}", code, e);
//! ```
#![cfg_attr(not(feature = "std"), no_std)]
#[cfg_attr(unix, path = "unix.rs")]
#[cfg_attr(windows, path = "windows.rs")]
#[cfg_attr(target_os = "wasi", path = "wasi.rs")]
#[cfg_attr(target_os = "hermit", path = "hermit.rs")]
mod sys;
use core::fmt;
#[cfg(feature = "std")]
use std::error::Error;
#[cfg(feature = "std")]
use std::io;
/// Wraps a platform-specific error code.
///
/// The `Display` instance maps the code to a human-readable string. It
/// calls [`strerror_r`][1] under POSIX, and [`FormatMessageW`][2] on
/// Windows.
///
#[derive(Copy, Clone, Eq, Ord, PartialEq, PartialOrd, Hash)]
pub struct Errno(pub i32);
impl fmt::Debug for Errno {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
sys::with_description(*self, |desc| {
fmt.debug_struct("Errno")
.field("code", &self.0)
.field("description", &desc.ok())
.finish()
})
}
}
impl fmt::Display for Errno {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
sys::with_description(*self, |desc| match desc {
Ok(desc) => fmt.write_str(desc),
Err(fm_err) => write!(
fmt,
"OS error {} ({} returned error {})",
self.0,
sys::STRERROR_NAME,
fm_err.0
),
})
}
}
impl From<Errno> for i32 {
fn from(e: Errno) -> Self {
e.0
}
}
#[cfg(feature = "std")]
impl Error for Errno {
// TODO: Remove when MSRV >= 1.27
#[allow(deprecated)]
fn description(&self) -> &str {
"system error"
}
}
#[cfg(feature = "std")]
impl From<Errno> for io::Error {
fn from(errno: Errno) -> Self {
io::Error::from_raw_os_error(errno.0)
}
}
/// Returns the platform-specific value of `errno`.
pub fn errno() -> Errno {
sys::errno()
}
/// Sets the platform-specific value of `errno`.
pub fn set_errno(err: Errno) {
sys::set_errno(err)
}
#[test]
fn it_works() {
let x = errno();
set_errno(x);
}
#[cfg(feature = "std")]
#[test]
fn it_works_with_to_string() {
let x = errno();
let _ = x.to_string();
}
#[cfg(feature = "std")]
#[test]
fn check_description() {
let expect = if cfg!(windows) {
"Incorrect function."
} else if cfg!(target_os = "illumos") {
"Not owner"
} else if cfg!(target_os = "wasi") {
"Argument list too long"
} else if cfg!(target_os = "haiku") {
"Operation not allowed"
} else {
"Operation not permitted"
};
let errno_code = if cfg!(target_os = "haiku") {
-2147483633
} else {
1
};
set_errno(Errno(errno_code));
assert_eq!(errno().to_string(), expect);
assert_eq!(
format!("{:?}", errno()),
format!(
"Errno {{ code: {}, description: Some({:?}) }}",
errno_code, expect
)
);
}
#[cfg(feature = "std")]
#[test]
fn check_error_into_errno() {
const ERROR_CODE: i32 = 1;
let error = io::Error::from_raw_os_error(ERROR_CODE);
let new_error: io::Error = Errno(ERROR_CODE).into();
assert_eq!(error.kind(), new_error.kind());
}