Process: Implement signal sending functions.

spevans · spevans · commit 128dac996885 · 2018-06-13T16:39:57.000+01:00
- Implements suspend(), resume(), interrupt() and terminate().

- Add --signal-test to xdgTestHelper for testing signals.
diff --git a/Foundation/Process.swift b/Foundation/Process.swift
@@ -507,11 +507,44 @@ open class Process: NSObject {
         self.processIdentifier = pid
     }
     
-    open func interrupt() { NSUnimplemented() } // Not always possible. Sends SIGINT.
-    open func terminate()  { NSUnimplemented() }// Not always possible. Sends SIGTERM.
-    
-    open func suspend() -> Bool { NSUnimplemented() }
-    open func resume() -> Bool { NSUnimplemented() }
+    open func interrupt() {
+        if isRunning && processIdentifier > 0 {
+            kill(processIdentifier, SIGINT)
+        }
+    }
+
+    open func terminate() {
+        if isRunning && processIdentifier > 0 {
+            kill(processIdentifier, SIGTERM)
+        }
+    }
+
+    // Every suspend() has to be balanced with a resume() so keep a count of both.
+    private var suspendCount = 0
+
+    open func suspend() -> Bool {
+        guard isRunning else {
+            return false
+        }
+
+        suspendCount += 1
+        if suspendCount == 1, processIdentifier > 0 {
+            kill(processIdentifier, SIGSTOP)
+        }
+        return true
+    }
+
+    open func resume() -> Bool {
+        guard isRunning else {
+            return true
+        }
+
+        suspendCount -= 1
+        if suspendCount == 0, processIdentifier > 0 {
+            kill(processIdentifier, SIGCONT)
+        }
+        return true
+    }
     
     // status
     open private(set) var processIdentifier: Int32 = -1
diff --git a/TestFoundation/TestProcess.swift b/TestFoundation/TestProcess.swift
@@ -29,6 +29,9 @@ class TestProcess : XCTestCase {
                    ("test_no_environment", test_no_environment),
                    ("test_custom_environment", test_custom_environment),
                    ("test_run", test_run),
+                   ("test_interrupt", test_interrupt),
+                   ("test_terminate", test_terminate),
+                   ("test_suspend_resume", test_suspend_resume),
         ]
 #endif
     }
@@ -385,6 +388,113 @@ class TestProcess : XCTestCase {
         fm.changeCurrentDirectoryPath(cwd)
     }
 
+    func test_interrupt() {
+        let helper = _SignalHelperRunner()
+        do {
+            try helper.start()
+        }  catch {
+            XCTFail("Cant run xdgTestHelper: \(error)")
+            return
+        }
+        if !helper.waitForReady() {
+            XCTFail("Didnt receive Ready from sub-process")
+            return
+        }
+
+        let now = DispatchTime.now().uptimeNanoseconds
+        let timeout = DispatchTime(uptimeNanoseconds: now + 2_000_000_000)
+
+        var count = 3
+        while count > 0 {
+            helper.process.interrupt()
+            guard helper.semaphore.wait(timeout: timeout) == .success else {
+                helper.process.terminate()
+                XCTFail("Timedout waiting for signal")
+                return
+            }
+
+            if helper.sigIntCount == 3 {
+                break
+            }
+            count -= 1
+        }
+        helper.process.terminate()
+        XCTAssertEqual(helper.sigIntCount, 3)
+        helper.process.waitUntilExit()
+        let terminationReason = helper.process.terminationReason
+        XCTAssertEqual(terminationReason, Process.TerminationReason.exit)
+        let status = helper.process.terminationStatus
+        XCTAssertEqual(status, 99)
+    }
+
+    func test_terminate() {
+        let cat = URL(fileURLWithPath: "/bin/cat", isDirectory: false)
+        guard let process = try? Process.run(cat, arguments: []) else {
+            XCTFail("Cant run /bin/cat")
+            return
+        }
+
+        process.terminate()
+        process.waitUntilExit()
+        let terminationReason = process.terminationReason
+        XCTAssertEqual(terminationReason, Process.TerminationReason.uncaughtSignal)
+        XCTAssertEqual(process.terminationStatus, SIGTERM)
+    }
+
+    func test_suspend_resume() {
+        let helper = _SignalHelperRunner()
+        do {
+            try helper.start()
+        }  catch {
+            XCTFail("Cant run xdgTestHelper: \(error)")
+            return
+        }
+        if !helper.waitForReady() {
+            XCTFail("Didnt receive Ready from sub-process")
+            return
+        }
+        let now = DispatchTime.now().uptimeNanoseconds
+        let timeout = DispatchTime(uptimeNanoseconds: now + 2_000_000_000)
+
+        func waitForSemaphore() -> Bool {
+            guard helper.semaphore.wait(timeout: timeout) == .success else {
+                helper.process.terminate()
+                XCTFail("Timedout waiting for signal")
+                return false
+            }
+            return true
+        }
+
+        XCTAssertTrue(helper.process.isRunning)
+        XCTAssertTrue(helper.process.suspend())
+        XCTAssertTrue(helper.process.isRunning)
+        XCTAssertTrue(helper.process.resume())
+        if waitForSemaphore() == false { return }
+        XCTAssertEqual(helper.sigContCount, 1)
+
+        XCTAssertTrue(helper.process.resume())
+        XCTAssertTrue(helper.process.suspend())
+        XCTAssertTrue(helper.process.resume())
+        XCTAssertEqual(helper.sigContCount, 1)
+
+        XCTAssertTrue(helper.process.suspend())
+        XCTAssertTrue(helper.process.suspend())
+        XCTAssertTrue(helper.process.resume())
+        if waitForSemaphore() == false { return }
+
+        helper.process.suspend()
+        helper.process.resume()
+        if waitForSemaphore() == false { return }
+        XCTAssertEqual(helper.sigContCount, 3)
+
+        helper.process.terminate()
+        helper.process.waitUntilExit()
+        XCTAssertFalse(helper.process.isRunning)
+        XCTAssertFalse(helper.process.suspend())
+        XCTAssertTrue(helper.process.resume())
+        XCTAssertTrue(helper.process.resume())
+    }
+
 #endif
 }
 
@@ -394,6 +504,89 @@ private enum Error: Swift.Error {
     case InvalidEnvironmentVariable(String)
 }
 
+// Run xdgTestHelper, wait for 'Ready' from the sub-process, then signal a semaphore.
+// Read lines from a pipe and store in a queue.
+class _SignalHelperRunner {
+    let process = Process()
+    let semaphore = DispatchSemaphore(value: 0)
+
+    private let outputPipe = Pipe()
+    private let sQueue = DispatchQueue(label: "io queue")
+    private let source: DispatchSourceRead
+
+    private var gotReady = false
+    private var bytesIn = Data()
+    private var _sigIntCount = 0
+    private var _sigContCount = 0
+    var sigIntCount: Int { return sQueue.sync { return _sigIntCount } }
+    var sigContCount: Int { return sQueue.sync { return _sigContCount } }
+
+
+    init() {
+        process.executableURL = xdgTestHelperURL()
+        process.environment = ProcessInfo.processInfo.environment
+        process.arguments = ["--signal-test"]
+        process.standardOutput = outputPipe.fileHandleForWriting
+
+        source = DispatchSource.makeReadSource(fileDescriptor: outputPipe.fileHandleForReading.fileDescriptor, queue: sQueue)
+        let workItem = DispatchWorkItem(block: { [weak self] in
+            if let strongSelf = self {
+                let newLine = UInt8(ascii: "\n")
+
+                strongSelf.bytesIn.append(strongSelf.outputPipe.fileHandleForReading.availableData)
+                if strongSelf.bytesIn.isEmpty {
+                    return
+                }
+                // Split the incoming data into lines.
+                while let index = strongSelf.bytesIn.index(of: newLine) {
+                    if index >= strongSelf.bytesIn.startIndex {
+                        // dont include the newline when converting to string
+                        let line = String(data: strongSelf.bytesIn[strongSelf.bytesIn.startIndex..<index], encoding: String.Encoding.utf8) ?? ""
+                        strongSelf.bytesIn.removeSubrange(strongSelf.bytesIn.startIndex...index)
+
+                        if strongSelf.gotReady == false && line == "Ready" {
+                            strongSelf.semaphore.signal()
+                            strongSelf.gotReady = true;
+                        }
+                        else if strongSelf.gotReady == true {
+                            if line == "Signal: SIGINT" {
+                                strongSelf._sigIntCount += 1
+                                strongSelf.semaphore.signal()
+                            }
+                            else if line == "Signal: SIGCONT" {
+                                strongSelf._sigContCount += 1
+                                strongSelf.semaphore.signal()
+                            }
+                        }
+                    }
+                }
+            }
+        })
+        source.setEventHandler(handler: workItem)
+    }
+
+    deinit {
+        source.cancel()
+        process.terminate()
+        process.waitUntilExit()
+    }
+
+    func start() throws {
+        source.resume()
+        try process.run()
+    }
+
+    func waitForReady() -> Bool {
+        let now = DispatchTime.now().uptimeNanoseconds
+        let timeout = DispatchTime(uptimeNanoseconds: now + 2_000_000_000)
+        guard semaphore.wait(timeout: timeout) == .success else {
+            process.terminate()
+            return false
+        }
+        return true
+    }
+}
+
 #if !os(Android)
 private func runTask(_ arguments: [String], environment: [String: String]? = nil, currentDirectoryPath: String? = nil) throws -> (String, String) {
     let process = Process()
diff --git a/TestFoundation/xdgTestHelper/main.swift b/TestFoundation/xdgTestHelper/main.swift
@@ -1,6 +1,6 @@
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2017 Swift project authors
+// Copyright (c) 2017 - 2018 Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See http://swift.org/LICENSE.txt for license information
@@ -55,15 +55,72 @@ class XDGCheck {
     }
 }
 
-if let arg = ProcessInfo.processInfo.arguments.last {
-    if arg == "--xdgcheck" {
-        XDGCheck.run()
-    }
-    if arg == "--getcwd" {
-        print(FileManager.default.currentDirectoryPath)
+// Used by TestProcess: test_interrupt(), test_suspend_resume()
+func signalTest() {
+
+    var signalSet = sigset_t()
+    sigemptyset(&signalSet)
+    sigaddset(&signalSet, SIGTERM)
+    sigaddset(&signalSet, SIGCONT)
+    sigaddset(&signalSet, SIGINT)
+    sigaddset(&signalSet, SIGALRM)
+    guard sigprocmask(SIG_BLOCK, &signalSet, nil) == 0 else {
+        fatalError("Cant block signals")
     }
-    if arg == "--echo-PWD" {
-        print(ProcessInfo.processInfo.environment["PWD"] ?? "")
+    // Timeout
+    alarm(3)
+
+    // On Linux, print() doesnt currently flush the output over the pipe so use
+    // write() for now. On macOS, print() works fine.
+    write(1, "Ready\n", 6)
+
+    while true {
+        var receivedSignal: Int32 = 0
+        let ret = sigwait(&signalSet, &receivedSignal)
+        guard ret == 0 else {
+            fatalError("sigwait() failed")
+        }
+        switch receivedSignal {
+        case SIGINT:
+            write(1, "Signal: SIGINT\n", 15)
+
+        case SIGCONT:
+            write(1, "Signal: SIGCONT\n", 16)
+
+        case SIGTERM:
+            print("Terminated")
+            exit(99)
+
+        case SIGALRM:
+            print("Timedout")
+            exit(127)
+
+        default:
+            let msg = "Unexpected signal: \(receivedSignal)"
+            fatalError(msg)
+        }
     }
 }
 
+var arguments = ProcessInfo.processInfo.arguments.dropFirst().makeIterator()
+
+guard let arg = arguments.next() else {
+    fatalError("The unit test must specify the correct number of flags and arguments.")
+}
+
+switch arg {
+case "--xdgcheck":
+    XDGCheck.run()
+
+case "--getcwd":
+    print(FileManager.default.currentDirectoryPath)
+
+case "--echo-PWD":
+    print(ProcessInfo.processInfo.environment["PWD"] ?? "")
+
+case "--signal-test":
+    signalTest()
+
+default:
+    fatalError("These arguments are not recognized. Only run this from a unit test.")
+}
