1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

//! 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(target_os = "wasi", feature(thread_local))]

#[cfg(unix)] extern crate libc;
#[cfg(windows)] extern crate winapi;
#[cfg(target_os = "dragonfly")] extern crate errno_dragonfly;
#[cfg(target_os = "wasi")] extern crate libc;
#[cfg(target_os = "hermit")] extern crate libc;

#[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 std::fmt;
use std::io;
use std::error::Error;

/// 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.
///
/// [1]: http://pubs.opengroup.org/onlinepubs/009695399/functions/strerror.html
/// [2]: https://msdn.microsoft.com/en-us/library/windows/desktop/ms679351%28v=vs.85%29.aspx
#[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 Into<i32> for Errno {
    fn into(self) -> i32 {
        self.0
    }
}

impl Error for Errno {
    // TODO: Remove when MSRV >= 1.27
    #[allow(deprecated)]
    fn description(&self) -> &str {
        "system error"
    }
}

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);
    let _ = x.to_string();
}

#[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 {
        "Operation not permitted"
    };

    set_errno(Errno(1));

    assert_eq!(errno().to_string(), expect);
    assert_eq!(
        format!("{:?}", errno()),
        format!("Errno {{ code: 1, description: Some({:?}) }}", expect));
}

#[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());
}