Add support for starting a detached process

runtime/bin/process_patch.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 patch class _WindowsCodePageDecoder {
   /* patch */ static String _decodeBytes(List<int> bytes)
       native "SystemEncodingToString";
 }
 
 
 patch class _WindowsCodePageEncoder {
   /* patch */ static List<int> _encodeString(String string)
       native "StringToSystemEncoding";
 }
 
 
 patch class Process {
   /* patch */ static Future<Process> start(
       String executable,
       List<String> arguments,
       {String workingDirectory,
        Map<String, String> environment,
        bool includeParentEnvironment: true,
-       bool runInShell: false}) {
+       bool runInShell: false,
+       bool detach: false}) {
     _ProcessImpl process = new _ProcessImpl(executable,
                                             arguments,
                                             workingDirectory,
                                             environment,
                                             includeParentEnvironment,
-                                            runInShell);
+                                            runInShell,
+                                            detach);
     return process._start();
   }
 
   /* patch */ static Future<ProcessResult> run(
       String executable,
       List<String> arguments,
       {String workingDirectory,
        Map<String, String> environment,
        bool includeParentEnvironment: true,
        bool runInShell: false,
@@ skipping 125 matching lines @@
 class _ProcessImpl extends _ProcessImplNativeWrapper with _ServiceObject
     implements Process {
   // Use default Map so we keep order.
   static Map<int, _ProcessImpl> _processes = new Map<int, _ProcessImpl>();
 
   _ProcessImpl(String path,
                List<String> arguments,
                String this._workingDirectory,
                Map<String, String> environment,
                bool includeParentEnvironment,
-               bool runInShell) : super() {
+               bool runInShell,
+               bool detach) : super() {
     _processes[_serviceId] = this;
     if (runInShell) {
       arguments = _getShellArguments(path, arguments);
       path = _getShellCommand();
     }
 
     if (path is !String) {
       throw new ArgumentError("Path is not a String: $path");
     }
     _path = path;
@@ skipping 36 matching lines @@
       Platform.environment.forEach((key, value) {
         assert(key is String);
         assert(value is String);
         // Do not override keys already set as part of environment.
         if (!environment.containsKey(key)) {
           _environment.add('$key=$value');
         }
       });
     }
 
-    // stdin going to process.
-    _stdin = new _StdSink(new _Socket._writePipe());
-    _stdin._sink._owner = this;
-    // stdout coming from process.
-    _stdout = new _StdStream(new _Socket._readPipe());
-    _stdout._stream._owner = this;
-    // stderr coming from process.
-    _stderr = new _StdStream(new _Socket._readPipe());
-    _stderr._stream._owner = this;
-    _exitHandler = new _Socket._readPipe();
+    if (detach is !bool) {
+      throw new ArgumentError("Detach is not a boolean: $detach");
+    }
+    _detach = detach;
+
+
+    if (!detach) {
+      // stdin going to process.
+      _stdin = new _StdSink(new _Socket._writePipe());
+      _stdin._sink._owner = this;
+      // stdout coming from process.
+      _stdout = new _StdStream(new _Socket._readPipe());
+      _stdout._stream._owner = this;
+      // stderr coming from process.
+      _stderr = new _StdStream(new _Socket._readPipe());
+      _stderr._stream._owner = this;
+      _exitHandler = new _Socket._readPipe();
+    }
     _ended = false;
     _started = false;
   }
 
   String get _serviceTypePath => 'io/processes';
   String get _serviceTypeName => 'Process';
 
   Map _toJSON(bool ref) {
     var r = {
       'id': _servicePath,
@@ skipping 103 matching lines @@
 
   int _intFromBytes(List<int> bytes, int offset) {
     return (bytes[offset] +
             (bytes[offset + 1] << 8) +
             (bytes[offset + 2] << 16) +
             (bytes[offset + 3] << 24));
   }
 
   Future<Process> _start() {
     var completer = new Completer();
+    if (!_detach) {
+      _exitCode = new Completer<int>();
+    }
     // TODO(ager): Make the actual process starting really async instead of
     // simulating it with a timer.
     Timer.run(() {
       var status = new _ProcessStartStatus();
-      bool success = _startNative(_path,
-                                  _arguments,
-                                  _workingDirectory,
-                                  _environment,
-                                  _stdin._sink._nativeSocket,
-                                  _stdout._stream._nativeSocket,
-                                  _stderr._stream._nativeSocket,
-                                  _exitHandler._nativeSocket,
-                                  status);
+      bool success =
+          _startNative(_path,
+                       _arguments,
+                       _workingDirectory,
+                       _environment,
+                       _detach,
+                       _detach ? null : _stdin._sink._nativeSocket,
+                       _detach ? null : _stdout._stream._nativeSocket,
+                       _detach ? null : _stderr._stream._nativeSocket,
+                       _detach ? null : _exitHandler._nativeSocket,
+                       status);
       if (!success) {
         completer.completeError(
             new ProcessException(_path,
                                  _arguments,
                                  status._errorMessage,
                                  status._errorCode));
         return;
       }
 
       _started = true;
 
       // Setup an exit handler to handle internal cleanup and possible
       // callback when a process terminates.
-      int exitDataRead = 0;
-      final int EXIT_DATA_SIZE = 8;
-      List<int> exitDataBuffer = new List<int>(EXIT_DATA_SIZE);
-      _exitHandler.listen((data) {
+      if (!_detach) {
+        int exitDataRead = 0;
+        final int EXIT_DATA_SIZE = 8;
+        List<int> exitDataBuffer = new List<int>(EXIT_DATA_SIZE);
+        _exitHandler.listen((data) {
 
-        int exitCode(List<int> ints) {
-          var code = _intFromBytes(ints, 0);
-          var negative = _intFromBytes(ints, 4);
-          assert(negative == 0 || negative == 1);
-          return (negative == 0) ? code : -code;
-        }
+          int exitCode(List<int> ints) {
+            var code = _intFromBytes(ints, 0);
+            var negative = _intFromBytes(ints, 4);
+            assert(negative == 0 || negative == 1);
+            return (negative == 0) ? code : -code;
+          }
 
-        void handleExit() {
-          _ended = true;
-          _exitCode.complete(exitCode(exitDataBuffer));
-          // Kill stdin, helping hand if the user forgot to do it.
-          _stdin._sink.destroy();
-          _processes.remove(_serviceId);
-        }
+          void handleExit() {
+            _ended = true;
+            _exitCode.complete(exitCode(exitDataBuffer));
+            // Kill stdin, helping hand if the user forgot to do it.
+            _stdin._sink.destroy();
+            _processes.remove(_serviceId);
+          }
 
-        exitDataBuffer.setRange(exitDataRead, exitDataRead + data.length, data);
-        exitDataRead += data.length;
-        if (exitDataRead == EXIT_DATA_SIZE) {
-          handleExit();
-        }
-      });
+          exitDataBuffer.setRange(
+              exitDataRead, exitDataRead + data.length, data);
+          exitDataRead += data.length;
+          if (exitDataRead == EXIT_DATA_SIZE) {
+            handleExit();
+          }
+        });
+      }
 
       completer.complete(this);
     });
     return completer.future;
   }
 
   ProcessResult _runAndWait(Encoding stdoutEncoding,
                             Encoding stderrEncoding) {
     var status = new _ProcessStartStatus();
+    _exitCode = new Completer<int>();
     bool success = _startNative(_path,
                                 _arguments,
                                 _workingDirectory,
                                 _environment,
+                                false,
                                 _stdin._sink._nativeSocket,
                                 _stdout._stream._nativeSocket,
                                 _stderr._stream._nativeSocket,
                                 _exitHandler._nativeSocket,
                                 status);
     if (!success) {
       throw new ProcessException(_path,
                                  _arguments,
                                  status._errorMessage,
                                  status._errorCode);
@@ skipping 16 matching lines @@
         result[0],
         result[1],
         getOutput(result[2], stdoutEncoding),
         getOutput(result[3], stderrEncoding));
   }
 
   bool _startNative(String path,
                     List<String> arguments,
                     String workingDirectory,
                     List<String> environment,
+                    bool detach,
                     _NativeSocket stdin,
                     _NativeSocket stdout,
                     _NativeSocket stderr,
                     _NativeSocket exitHandler,
                     _ProcessStartStatus status) native "Process_Start";
 
   _wait(_NativeSocket stdin,
         _NativeSocket stdout,
         _NativeSocket stderr,
         _NativeSocket exitHandler) native "Process_Wait";
 
   Stream<List<int>> get stdout {
     return _stdout;
   }
 
   Stream<List<int>> get stderr {
     return _stderr;
   }
 
   IOSink get stdin {
     return _stdin;
   }
 
-  Future<int> get exitCode => _exitCode.future;
+  Future<int> get exitCode => _exitCode != null ? _exitCode.future : null;
 
   bool kill([ProcessSignal signal = ProcessSignal.SIGTERM]) {
     if (signal is! ProcessSignal) {
       throw new ArgumentError(
           "Argument 'signal' must be a ProcessSignal");
     }
     assert(_started);
     if (_ended) return false;
     return _kill(this, signal._signalNumber);
   }
 
   bool _kill(Process p, int signal) native "Process_Kill";
 
   int get pid => _ProcessUtils._pid(this);
 
   String _path;
   List<String> _arguments;
   String _workingDirectory;
   List<String> _environment;
+  bool _detach;
   // Private methods of Socket are used by _in, _out, and _err.
   _StdSink _stdin;
   _StdStream _stdout;
   _StdStream _stderr;
   Socket _exitHandler;
   bool _ended;
   bool _started;
-  final Completer<int> _exitCode = new Completer<int>();
+  Completer<int> _exitCode;
 }
 
 
 // _NonInteractiveProcess is a wrapper around an interactive process
 // that buffers output so it can be delivered when the process exits.
 // _NonInteractiveProcess is used to implement the Process.run
 // method.
 Future<ProcessResult> _runNonInteractiveProcess(String path,
                                                 List<String> arguments,
                                                 String workingDirectory,
@@ skipping 49 matching lines @@
       Map<String, String> environment,
       bool includeParentEnvironment,
       bool runInShell,
       Encoding stdoutEncoding,
       Encoding stderrEncoding) {
   var process = new _ProcessImpl(executable,
                                  arguments,
                                  workingDirectory,
                                  environment,
                                  includeParentEnvironment,
-                                 runInShell);
+                                 runInShell,
+                                 false);
   return process._runAndWait(stdoutEncoding, stderrEncoding);
 }
 
 
 class _ProcessResult implements ProcessResult {
   const _ProcessResult(int this.pid,
                        int this.exitCode,
                        this.stdout,
                        this.stderr);
 
   final int pid;
   final int exitCode;
   final stdout;
   final stderr;
 }