在 Swift 中终止 macOS 命令行工具的子进程

Question

我正在用 swift 编写一个执行 shell 命令的 macOS 命令行工具：

let process = Process()
process.launchPath = "/bin/sleep"
process.arguments = ["100"]
process.launch()
process.waitUntilExit()

但是，如果向我的程序发送中断 (CTRL-C) 或终止信号，这些 shell 命令不会终止，而是继续执行。

如果我的程序意外终止，有没有办法自动终止它们？

Answer 1

这是我们在使用两个管道子进程时为了对中断 (CTRL-C) 做出反应所做的操作。

背后的想法：阻塞 waitUntilExit() 调用替换为异步 terminationHandler。无限循环dispatchMain() 用于服务调度事件。在接收到Interrupt 信号时，我们在子进程上调用interrupt()。

封装子进程启动和中断逻辑的示例类：

class AppTester: Builder {

   private var processes: [Process] = [] // Keeps references to launched processes.

   func test(completion: @escaping (Int32) -> Void) {

      let xcodebuildProcess = Process(executableName: "xcodebuild", arguments: ...)
      let xcprettyProcess = Process(executableName: "xcpretty", arguments: ...)

      // Organising pipe between processes. Like `xcodebuild ... | xcpretty` in shell
      let pipe = Pipe()
      xcodebuildProcess.standardOutput = pipe
      xcprettyProcess.standardInput = pipe

      // Assigning `terminationHandler` for needed subprocess.
      processes.append(xcodebuildProcess)
      xcodebuildProcess.terminationHandler = { process in
         completion(process.terminationStatus)
      }

      xcodebuildProcess.launch()
      xcprettyProcess.launch()
      // Note. We should not use blocking `waitUntilExit()` call.
   }

   func interrupt() {
      // Interrupting running processes (if any).
      processes.filter { $0.isRunning }.forEach { $0.interrupt() }
   }
}

用法（即main.swift）：

let tester = AppTester(...)
tester.test(....) {
   if $0 == EXIT_SUCCESS {
      // Do some other work.
   } else {
      exit($0)
   }
}

// Making Interrupt signal listener.
let source = DispatchSource.makeSignalSource(signal: SIGINT)
source.setEventHandler {
   tester.interrupt() // Will interrupt running processes (if any).
   exit(SIGINT)
}
source.resume()
dispatchMain() // Starting dispatch loop. This function never returns.

shell 中的示例输出：

...
▸ Running script 'Run Script: Verify Sources'
▸ Processing Framework-Info.plist
▸ Running script 'Run Script: Verify Sources'
▸ Linking AppTestability
^C** BUILD INTERRUPTED **