[NSTask] Change argv[0] to full path + fixes combining stdout+stderr (#353)

* Clarified TestNSTask tests

* [NSTask] Redirecting both stdout and stderr fails

* [NSTask] Fix issue capturing stdout and stderr to same pipe

* [NSTask] Pass complete path as argv[0]

This allows executables to derive their own absolute
path. SwiftPM relies on this value to derive the compiler
path and fake toolchain path.

Author: Bouke

Foundation/NSTask.swift

@@ -194,7 +194,7 @@ public class NSTask : NSObject {
 
         // Convert the arguments array into a posix_spawn-friendly format
 
-        var args = [launchPath.lastPathComponent]
+        var args = [launchPath]
         if let arguments = self.arguments {
             args.append(contentsOf: arguments)
         }
@@ -307,61 +307,52 @@ public class NSTask : NSObject {
         #else
             var fileActions: posix_spawn_file_actions_t = posix_spawn_file_actions_t()
         #endif
-        posix_spawn_file_actions_init(&fileActions)
+        try! posix(posix_spawn_file_actions_init(&fileActions))
+        defer { posix_spawn_file_actions_destroy(&fileActions) }
 
-        switch self.standardInput {
+        switch standardInput {
         case let pipe as NSPipe:
-            posix_spawn_file_actions_adddup2(&fileActions, pipe.fileHandleForReading.fileDescriptor, STDIN_FILENO)
-            posix_spawn_file_actions_addclose(&fileActions, pipe.fileHandleForWriting.fileDescriptor)
+            try! posix(posix_spawn_file_actions_adddup2(&fileActions, pipe.fileHandleForReading.fileDescriptor, STDIN_FILENO))
+            try! posix(posix_spawn_file_actions_addclose(&fileActions, pipe.fileHandleForWriting.fileDescriptor))
         case let handle as NSFileHandle:
-            posix_spawn_file_actions_adddup2(&fileActions, handle.fileDescriptor, STDIN_FILENO)
-            posix_spawn_file_actions_addclose(&fileActions, handle.fileDescriptor)
+            try! posix(posix_spawn_file_actions_adddup2(&fileActions, handle.fileDescriptor, STDIN_FILENO))
         default: break
         }
 
-        switch self.standardOutput {
+        switch standardOutput {
         case let pipe as NSPipe:
-            posix_spawn_file_actions_adddup2(&fileActions, pipe.fileHandleForWriting.fileDescriptor, STDOUT_FILENO)
-            posix_spawn_file_actions_addclose(&fileActions, pipe.fileHandleForWriting.fileDescriptor)
+            try! posix(posix_spawn_file_actions_adddup2(&fileActions, pipe.fileHandleForWriting.fileDescriptor, STDOUT_FILENO))
+            try! posix(posix_spawn_file_actions_addclose(&fileActions, pipe.fileHandleForReading.fileDescriptor))
         case let handle as NSFileHandle:
-            posix_spawn_file_actions_adddup2(&fileActions, handle.fileDescriptor, STDOUT_FILENO)
-            posix_spawn_file_actions_addclose(&fileActions, handle.fileDescriptor)
+            try! posix(posix_spawn_file_actions_adddup2(&fileActions, handle.fileDescriptor, STDOUT_FILENO))
         default: break
         }
 
-        switch self.standardError {
+        switch standardError {
         case let pipe as NSPipe:
-            posix_spawn_file_actions_adddup2(&fileActions, pipe.fileHandleForWriting.fileDescriptor, STDERR_FILENO)
-            posix_spawn_file_actions_addclose(&fileActions, pipe.fileHandleForWriting.fileDescriptor)
+            try! posix(posix_spawn_file_actions_adddup2(&fileActions, pipe.fileHandleForWriting.fileDescriptor, STDERR_FILENO))
+            try! posix(posix_spawn_file_actions_addclose(&fileActions, pipe.fileHandleForReading.fileDescriptor))
         case let handle as NSFileHandle:
-            posix_spawn_file_actions_adddup2(&fileActions, handle.fileDescriptor, STDERR_FILENO)
-            posix_spawn_file_actions_addclose(&fileActions, handle.fileDescriptor)
+            try! posix(posix_spawn_file_actions_adddup2(&fileActions, handle.fileDescriptor, STDERR_FILENO))
         default: break
         }
 
         // Launch
 
         var pid = pid_t()
-        let status = posix_spawn(&pid, launchPath, &fileActions, nil, argv, envp)
-
-        // cleanup file_actions
-        posix_spawn_file_actions_destroy(&fileActions)
+        try! posix(posix_spawn(&pid, launchPath, &fileActions, nil, argv, envp))
 
         // Close the write end of the input and output pipes.
-        if let pipe = self.standardInput as? NSPipe {
+        if let pipe = standardInput as? NSPipe {
             pipe.fileHandleForReading.closeFile()
         }
-        if let pipe = self.standardOutput as? NSPipe {
+        if let pipe = standardOutput as? NSPipe {
             pipe.fileHandleForWriting.closeFile()
         }
-        if let pipe = self.standardError as? NSPipe {
+        if let pipe = standardError as? NSPipe {
             pipe.fileHandleForWriting.closeFile()
         }
 
-        guard status == 0 else {
-            fatalError()
-        }
-
         close(taskSocketPair[1])
 
         self.runLoop = NSRunLoop.currentRunLoop()
@@ -427,4 +418,9 @@ extension NSTask {
 
 public let NSTaskDidTerminateNotification: String = "NSTaskDidTerminateNotification"
 
-
+private func posix(_ code: Int32) throws {
+    switch code {
+    case 0: return
+    default: throw NSError(domain: NSPOSIXErrorDomain, code: Int(code), userInfo: nil)
+    }
+}

TestFoundation/TestNSTask.swift

@@ -27,6 +27,7 @@ class TestNSTask : XCTestCase {
                    ("test_pipe_stdin", test_pipe_stdin),
                    ("test_pipe_stdout", test_pipe_stdout),
                    ("test_pipe_stderr", test_pipe_stderr),
+                   ("test_pipe_stdout_and_stderr_same_pipe", test_pipe_stdout_and_stderr_same_pipe),
                    ("test_file_stdout", test_file_stdout),
                    ("test_passthrough_environment", test_passthrough_environment),
                    ("test_no_environment", test_no_environment),
@@ -163,7 +164,29 @@ class TestNSTask : XCTestCase {
             XCTFail("Could not read stdout")
             return
         }
-        XCTAssertEqual(string, "cat: invalid_file_name: No such file or directory\n")
+        XCTAssertEqual(string, "/bin/cat: invalid_file_name: No such file or directory\n")
+    }
+
+    func test_pipe_stdout_and_stderr_same_pipe() {
+        let task = NSTask()
+
+        task.launchPath = "/bin/cat"
+        task.arguments = ["invalid_file_name"]
+
+        let pipe = NSPipe()
+        task.standardOutput = pipe
+        task.standardError = pipe
+
+        task.launch()
+        task.waitUntilExit()
+        XCTAssertEqual(task.terminationStatus, 1)
+
+        let data = pipe.fileHandleForReading.availableData
+        guard let string = String(data: data, encoding: NSASCIIStringEncoding) else {
+            XCTFail("Could not read stdout")
+            return
+        }
+        XCTAssertEqual(string, "/bin/cat: invalid_file_name: No such file or directory\n")
     }
 
     func test_file_stdout() {
@@ -188,19 +211,36 @@ class TestNSTask : XCTestCase {
             XCTAssertEqual(string, "/usr/bin/which\n")
         }
     }
-
+    
     func test_passthrough_environment() {
-        XCTAssertGreaterThan(env(environment: nil).count, 0)
+        do {
+            let output = try runTask(["/usr/bin/env"], environment: nil)
+            let env = try parseEnv(output)
+            XCTAssertGreaterThan(env.count, 0)
+        } catch let error {
+            XCTFail("Test failed: \(error)")
+        }
     }
 
     func test_no_environment() {
-        XCTAssertEqual(env(environment: [:]).count, 0)
+        do {
+            let output = try runTask(["/usr/bin/env"], environment: [:])
+            let env = try parseEnv(output)
+            XCTAssertEqual(env.count, 0)
+        } catch let error {
+            XCTFail("Test failed: \(error)")
+        }
     }
 
     func test_custom_environment() {
-        let input = ["HELLO": "WORLD", "HOME": "CUPERTINO"]
-        let output = env(environment: input)
-        XCTAssertEqual(output, input)
+        do {
+            let input = ["HELLO": "WORLD", "HOME": "CUPERTINO"]
+            let output = try runTask(["/usr/bin/env"], environment: input)
+            let env = try parseEnv(output)
+            XCTAssertEqual(env, input)
+        } catch let error {
+            XCTFail("Test failed: \(error)")
+        }
     }
 }
 
@@ -216,31 +256,47 @@ private func mkstemp(template: String, body: @noescape (NSFileHandle) throws ->
     }
 }
 
-private func env(environment: [String: String]?) -> [String: String] {
+private enum Error: ErrorProtocol {
+    case TerminationStatus(Int32)
+    case UnicodeDecodingError(NSData)
+    case InvalidEnvironmentVariable(String)
+}
+
+private func runTask(_ arguments: [String], environment: [String: String]? = nil) throws -> String {
     let task = NSTask()
-    task.launchPath = "/usr/bin/env"
+
+    var arguments = arguments
+    task.launchPath = arguments.removeFirst()
+    task.arguments = arguments
     task.environment = environment
 
     let pipe = NSPipe()
     task.standardOutput = pipe
-
+    task.standardError = pipe
     task.launch()
     task.waitUntilExit()
-    XCTAssertEqual(task.terminationStatus, 0)
+
+    guard task.terminationStatus == 0 else {
+        throw Error.TerminationStatus(task.terminationStatus)
+    }
 
     let data = pipe.fileHandleForReading.availableData
-    guard let string = String(data: data, encoding: NSUTF8StringEncoding) else {
-        XCTFail("Could not read stdout")
-        return [:]
+    guard let output = String(data: data, encoding: NSUTF8StringEncoding) else {
+        throw Error.UnicodeDecodingError(data)
     }
 
+    return output
+}
+
+private func parseEnv(_ env: String) throws -> [String: String] {
     var result = [String: String]()
-    for variable in string.components(separatedBy: "\n") where variable != "" {
-        guard let range = variable.range(of: "=") else {
-            XCTFail("Could not parse environment variable: \"\(variable)\"")
-            continue
+    for line in env.components(separatedBy: "\n") where line != "" {
+        guard let range = line.range(of: "=") else {
+            throw Error.InvalidEnvironmentVariable(line)
         }
-        result[variable.substring(to: range.lowerBound)] = variable.substring(from: range.upperBound)
+        result[line.substring(to: range.lowerBound)] = line.substring(from: range.upperBound)
     }
     return result
 }
+
+