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// Simple interface for making a socat process and interacting with it.
// Assumes access to the `socat` command as a child process; if it's not
// present, it will fall back to just writing to the specified file.
const EventEmitter = require('events')
const { spawn } = require('child_process')
const { killProcess, commandExists } = require('./general-util')
const { promisify } = require('util')
const fs = require('fs')
const path = require('path')
const writeFile = promisify(fs.writeFile)
module.exports = class Socat extends EventEmitter {
constructor(path) {
super()
this.setPath(path)
}
setPath(path) {
this.stop()
this.path = path
}
async start() {
this.stop()
if (await commandExists('socat')) {
this.subprocess = spawn('socat', ['-', this.path])
this.subprocess.stdout.on('data', data => this.emit('data', data))
this.subprocess.on('close', () => {
this.subprocess = null
})
this.subprocess.stdin.on('error', err => {
this.stop()
})
}
}
async stop() {
const proc = this.subprocess
if (proc) {
this.subprocess = null
await killProcess(proc)
}
}
async dispose() {
// Don't accept any more messages.
this.disposed = true
await this.stop()
}
async send(message) {
if (this.disposed) {
return
}
if (!this.subprocess) {
await this.start()
}
if (this.subprocess) {
try {
this.subprocess.stdin.write(message + '\r\n')
} catch (error) {
// There's no guarantee we'll actually suceed to write - the process
// or pipe we're writing to could have closed unexpectedly. If that
// happens, unestablish the socat process; it'll try to reconnect if
// we send another message.
this.stop()
}
} else {
try {
await writeFile(path.resolve(__dirname, this.path), message + '\r\n')
} catch (error) {
// :shrug: We tried!
// -- It's possible to get here if the specified path isn't an actual
// device, which is the case on Linux. Writing to that file (hopefully)
// works on Windows though, which is the case we're trying to support
// here. (On Linux you should have socat installed.)
}
}
}
}
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