在Swift中终止macOS命令行工具的子进程

Question

I'm writing a macOS command line tool in swift which executes shell commands:

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

However, if an interrupt ( CTRL-C ) or a terminate signal gets sent to my program, these shell commands don't get terminated and just continue with their execution.

Is there a way to automatically terminate them if my program gets terminated unexpectedly?

Answer 1

Here is what we did in order to react on interrupt ( CTRL-C ) when using two piped subprocesses.

Idea behind : Blocking waitUntilExit() call replaced with async terminationHandler . Infinite loop dispatchMain() used to serve dispatch events. On receiving Interrupt signal we calling interrupt() on subprocesses.

Example class which incapsulates subprocess launch and interrupt logic:

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() }
   }
}

Usage (ie 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.

Example output in shell:

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