1# Signal-hook 2 3[](https://github.com/vorner/signal-hook/actions) 4[](https://codecov.io/gh/vorner/signal-hook) 5[](https://docs.rs/signal-hook) 6 7Library for safe and correct Unix signal handling in Rust. 8 9Unix signals are inherently hard to handle correctly, for several reasons: 10 11* They are a global resource. If a library wants to set its own signal handlers, 12 it risks disturbing some other library. It is possible to chain the previous 13 signal handler, but then it is impossible to remove the old signal handlers 14 from the chains in any practical manner. 15* They can be called from whatever thread, requiring synchronization. Also, as 16 they can interrupt a thread at any time, making most handling race-prone. 17* According to the POSIX standard, the set of functions one may call inside a 18 signal handler is limited to very few of them. To highlight, mutexes (or other 19 locking mechanisms) and memory allocation and deallocation are *not* allowed. 20 21This library aims to solve some of the problems. It provides a global registry 22of actions performed on arrival of signals. It is possible to register multiple 23actions for the same signal and it is possible to remove the actions later on. 24If there was a previous signal handler when the first action for a signal is 25registered, it is chained (but the original one can't be removed). 26 27Besides the basic registration of an arbitrary action, several helper actions 28are provided to cover the needs of the most common use cases, available from 29safe Rust. 30 31For further details, see the [documentation](https://docs.rs/signal-hook). 32 33## Example 34 35(This likely does a lot more than you need in each individual application, it's 36more of a show-case of what everything is possible, not of what you need to do 37each time). 38 39```rust 40use std::io::Error; 41use std::sync::Arc; 42use std::sync::atomic::{AtomicBool, Ordering}; 43 44fn main() -> Result<(), Error> { 45 let term = Arc::new(AtomicBool::new(false)); 46 signal_hook::flag::register(signal_hook::consts::SIGTERM, Arc::clone(&term))?; 47 while !term.load(Ordering::Relaxed) { 48 // Do some time-limited stuff here 49 // (if this could block forever, then there's no guarantee the signal will have any 50 // effect). 51 } 52 Ok(()) 53} 54``` 55 56## License 57 58Licensed under either of 59 60 * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0) 61 * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) 62 63at your option. 64 65### Contribution 66 67Unless you explicitly state otherwise, any contribution intentionally 68submitted for inclusion in the work by you, as defined in the Apache-2.0 69license, shall be dual licensed as above, without any additional terms 70or conditions. 71
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