SR-13861: Process should spawn a child process it its own process group.

Sources/Foundation/Process.swift

@@ -944,11 +944,17 @@ open class Process: NSObject {
             try _throwIfPosixError(_CFPosixSpawnFileActionsAddClose(fileActions, fd))
         }
 
-        #if canImport(Darwin)
+#if canImport(Darwin)
         var spawnAttrs: posix_spawnattr_t? = nil
         try _throwIfPosixError(posix_spawnattr_init(&spawnAttrs))
+        try _throwIfPosixError(posix_spawnattr_setflags(&spawnAttrs, .init(POSIX_SPAWN_SETPGROUP)))
         try _throwIfPosixError(posix_spawnattr_setflags(&spawnAttrs, .init(POSIX_SPAWN_CLOEXEC_DEFAULT)))
-        #else
+#else
+        var spawnAttrs: posix_spawnattr_t = posix_spawnattr_t()
+        try _throwIfPosixError(posix_spawnattr_init(&spawnAttrs))
+        try _throwIfPosixError(posix_spawnattr_setflags(&spawnAttrs, .init(POSIX_SPAWN_SETPGROUP)))
+
+        // POSIX_SPAWN_CLOEXEC_DEFAULT is an Apple extension so emulate it.
         for fd in 3 ... findMaximumOpenFD() {
             guard adddup2[fd] == nil &&
                   !addclose.contains(fd) &&
@@ -957,7 +963,7 @@ open class Process: NSObject {
             }
             try _throwIfPosixError(_CFPosixSpawnFileActionsAddClose(fileActions, fd))
         }
-        #endif
+#endif
 
         let fileManager = FileManager()
         let previousDirectoryPath = fileManager.currentDirectoryPath
@@ -972,16 +978,10 @@ open class Process: NSObject {
 
         // Launch
         var pid = pid_t()
-        #if os(macOS)
         guard _CFPosixSpawn(&pid, launchPath, fileActions, &spawnAttrs, argv, envp) == 0 else {
             throw _NSErrorWithErrno(errno, reading: true, path: launchPath)
         }
-        #else
-        guard _CFPosixSpawn(&pid, launchPath, fileActions, nil, argv, envp) == 0 else {
-            throw _NSErrorWithErrno(errno, reading: true, path: launchPath)
-        }
-        #endif
-
+        posix_spawnattr_destroy(&spawnAttrs)
 
         // Close the write end of the input and output pipes.
         if let pipe = standardInput as? Pipe {

Tests/Foundation/Tests/TestProcess.swift

@@ -806,6 +806,35 @@ class TestProcess : XCTestCase {
         }
     }
 
+    func test_processGroup() throws {
+        // The process group of the child process should be different to the parent's.
+        let process = Process()
+
+        process.executableURL = xdgTestHelperURL()
+        process.arguments = ["--pgrp"]
+        let pipe = Pipe()
+        process.standardOutput = pipe
+        process.standardError = nil
+
+        try process.run()
+        process.waitUntilExit()
+        XCTAssertEqual(process.terminationStatus, 0)
+
+        let data = pipe.fileHandleForReading.availableData
+        guard let string = String(data: data, encoding: .ascii) else {
+            XCTFail("Could not read stdout")
+            return
+        }
+
+        let parts = string.trimmingCharacters(in: .newlines).components(separatedBy: ": ")
+        guard parts.count == 2, parts[0] == "pgrp", let childPgrp = Int(parts[1]) else {
+            XCTFail("Could not pgrp fron stdout")
+            return
+        }
+        let parentPgrp = Int(getpgrp())
+        XCTAssertNotEqual(parentPgrp, childPgrp, "Child process group \(parentPgrp) should not equal parent process group \(childPgrp)")
+    }
+
     static var allTests: [(String, (TestProcess) -> () throws -> Void)] {
         var tests = [
             ("test_exit0" , test_exit0),
@@ -835,6 +864,7 @@ class TestProcess : XCTestCase {
             ("test_currentDirectory", test_currentDirectory),
             ("test_pipeCloseBeforeLaunch", test_pipeCloseBeforeLaunch),
             ("test_multiProcesses", test_multiProcesses),
+            ("test_processGroup", test_processGroup),
         ]
 
 #if !os(Windows)

Tests/Tools/XDGTestHelper/main.swift

@@ -274,6 +274,10 @@ case "--signal-test":
 
 case "--print-open-file-descriptors":
     printOpenFileDescriptors()
+
+case "--pgrp":
+    print("pgrp: \(getpgrp())")
+
 #endif
 
 default: