# errno [![CI](https://github.com/lambda-fairy/rust-errno/actions/workflows/main.yml/badge.svg)](https://github.com/lambda-fairy/rust-errno/actions/workflows/main.yml) [![Cargo](https://img.shields.io/crates/v/errno.svg)](https://crates.io/crates/errno)
Cross-platform interface to the [`errno`][errno] variable. Works on Rust 1.56 or newer.
Documentation is available at <https://docs.rs/errno>.
[errno]: https://en.wikipedia.org/wiki/Errno.h
## Dependency
Add to your `Cargo.toml`:
```toml
[dependencies]
errno = "*"
```
## Comparison with `std::io::Error`
The standard library provides [`Error::last_os_error`][last_os_error] which fetches `errno` in the same way.
This crate provides these extra features:
- No heap allocations
- Optional `#![no_std]` support
- A `set_errno` function
[last_os_error]: https://doc.rust-lang.org/std/io/struct.Error.html#method.last_os_error
## Examples
```rust
extern crate errno;
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);
```
## `#![no_std]`
Enable `#![no_std]` support by disabling the default `std` feature:
```toml
[dependencies]
errno = { version = "*", default-features = false }
```
The `Error` impl will be unavailable.