在Golang中将控制信号转换为字节ASCII十六进制代码

Question

I am trying to capture signals like ctrl+c, ctrl+z, ctrl+\ in golang and write its equivalent hex code to websocket. I am doing something like below.

func (c *poc) writePump() {
    var b = make([]byte, 1)
    d := make(chan os.Signal, 1)
    signal.Notify(d, syscall.SIGINT, syscall.SIGTSTP, syscall.SIGQUIT)

    for {
        os.Stdin.Read(b)
        err = c.ws.WriteMessage(websocket.TextMessage, b)

        go func() {
            for {
                s := <-d
                err = cli.sendControlSignalToWebsockets(s)
            }
        }()

        if err != nil {
            log.Printf("Failed to send UTF8 char: %s", err)
        }
    }
}

func (c *poc) sendControlSignalToWebsockets(s os.Signal) error {
    var err error

    switch s {
    case syscall.SIGINT:
        err = c.ws.WriteMessage(websocket.TextMessage, []byte{'\003'})
    case syscall.SIGTSTP:
        err = c.ws.WriteMessage(websocket.TextMessage, []byte{'\x1a'})
    case syscall.SIGQUIT:
        err = c.ws.WriteMessage(websocket.TextMessage, []byte{'\x1c'})
    }

    if err != nil {
        return err
    }
    return nil
}

Instead I want to do something like, capturing all signals and instead of hardcoding each signals equivalent to it's hexcode, convert signal to hexcode.

func (c *poc) writePump() {
    var b = make([]byte, 1)
    d := make(chan os.Signal, 1)
    signal.Notify(d)

    for {
        os.Stdin.Read(b)
        err = c.ws.WriteMessage(websocket.TextMessage, b)

        go func() {
            for {
                s := <-d
                //???? do some conversions and write it to websocket
            }
        }()

        if err != nil {
            log.Printf("Failed to send UTF8 char: %s", err)
        }
    }
}

Curious to know if anyone has any idea. Thanks!

Answer 1

It sounds like you're trying to communicate a signal over a websocket. And thus you need a way to encode it won't get confused with other characters so using the unprintable ascii characters is a reasonable move.

Since there is no convention for mapping syscall signals into a byte, you can't just import it - but good news! - you get to create your own!

Create a map[syscall.Signal]byte or map[os.Signal]byte and do the translation from there:

// Create a mapping between syscalls and bytes
var syscallByteMap = map[syscall.Signal]byte{
  syscall.SIGINT: '\003',
  ...more here...
}

...truncated...

        go func() {
        for {
            s := <-d
            // Look up the signal in the map
            b, ok := syscallByteMap[s]
            if ok {
                err = c.ws.WriteMessage(websocket.TextMessage, []byte{b})
            } else {
                err = nil
            }

        }
    }()