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//! Implementation of `errno` functionality for Windows.
//!
//! Adapted from `src/libstd/sys/windows/os.rs` in the Rust distribution.
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use core::char::{self, REPLACEMENT_CHARACTER};
use core::ptr;
use core::str;
use windows_sys::Win32::Foundation::{GetLastError, SetLastError, WIN32_ERROR};
use windows_sys::Win32::System::Diagnostics::Debug::{
FormatMessageW, FORMAT_MESSAGE_FROM_SYSTEM, FORMAT_MESSAGE_IGNORE_INSERTS,
};
use crate::Errno;
fn from_utf16_lossy<'a>(input: &[u16], output: &'a mut [u8]) -> &'a str {
let mut output_len = 0;
for c in char::decode_utf16(input.iter().copied().take_while(|&x| x != 0))
.map(|x| x.unwrap_or(REPLACEMENT_CHARACTER))
{
let c_len = c.len_utf8();
if c_len > output.len() - output_len {
break;
}
c.encode_utf8(&mut output[output_len..]);
output_len += c_len;
}
unsafe { str::from_utf8_unchecked(&output[..output_len]) }
}
pub fn with_description<F, T>(err: Errno, callback: F) -> T
where
F: FnOnce(Result<&str, Errno>) -> T,
{
// This value is calculated from the macro
// MAKELANGID(LANG_SYSTEM_DEFAULT, SUBLANG_SYS_DEFAULT)
let lang_id = 0x0800_u32;
let mut buf = [0u16; 2048];
unsafe {
let res = FormatMessageW(
FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
ptr::null_mut(),
err.0 as u32,
lang_id,
buf.as_mut_ptr(),
buf.len() as u32,
ptr::null_mut(),
);
if res == 0 {
// Sometimes FormatMessageW can fail e.g. system doesn't like lang_id
let fm_err = errno();
return callback(Err(fm_err));
}
let mut msg = [0u8; 2048];
let msg = from_utf16_lossy(&buf[..res as usize], &mut msg[..]);
// Trim trailing CRLF inserted by FormatMessageW
callback(Ok(msg.trim_end()))
}
}
pub const STRERROR_NAME: &str = "FormatMessageW";
pub fn errno() -> Errno {
unsafe { Errno(GetLastError() as i32) }
}
pub fn set_errno(Errno(errno): Errno) {
unsafe { SetLastError(errno as WIN32_ERROR) }
}