How to trap OS signals using swift

SignalTrap.swift

enum SignalTrap {
    
    typealias SignalHandler = @convention(c)(Int32) -> Void
    
    static func handle(signal:Int32, action: @escaping SignalHandler) {
        typealias SignalAction = sigaction
        
        var sigAction = sigaction()
        sigAction.__sigaction_u = unsafeBitCast(action, to: __sigaction_u.self)
        sigaction(signal, &sigAction, nil)
    }
}

// ---------------------------------------------------------
// Usage
SignalTrap.handle(signal: SIGHUP) { value in
    print("Signal value: \(value)")
}

// ---------------------------------------------------------
// Testing
// # Run command
// $ ps -ax MyApp 
//
// # Get result similar to
// 12345 ttys000    0:00.01 MyApp
//
// # Send signal to process
// $ kill -HUP 12345

// ---------------------------------------------------------
// References
// * $ man sigaction - sigaction manual
// * https://dev.iachieved.it/iachievedit/trapping-signals-with-swift-on-linux/
// * https://github.com/alexito4/Trap/blob/master/Sources/Trap.swift