Reimplement devfs in dart. Implementation now writes to disk.

runtime/bin/vmservice/vmservice_io.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.
 
 library vmservice_io;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
@@ skipping 42 matching lines @@
     }
   }
   if (_registerSignalHandlerTimer != null) {
     _registerSignalHandlerTimer.cancel();
     _registerSignalHandlerTimer = null;
   }
   // Call out to embedder's shutdown callback.
   _shutdown();
 }
 
+Future<Uri> createTempDirCallback(String base) async {
+  Directory temp = await Directory.systemTemp.createTemp(base);
+  return temp.uri;
+}
+
+Future deleteDirCallback(Uri path) async {
+  Directory dir = new Directory.fromUri(path);
+  await dir.delete(recursive: true);
+}
+
+Future writeFileCallback(Uri path, List<int> bytes) async {
+  var file = await new File.fromUri(path);
+  await file.writeAsBytes(bytes);
+}
+
+Future<List<int>> readFileCallback(Uri path) async {
+  var file = await new File.fromUri(path);
+  return await file.readAsBytes();
+}
+
+Future<List<Map<String,String>>> listFilesCallback(Uri dirPath) async {
+  var dir = new Directory.fromUri(dirPath);
+  var dirPathStr = dirPath.path;
+  var stream = dir.list(recursive: true);
+  var result = [];
+  await for (var fileEntity in stream) {
+    var stat = await fileEntity.stat();
+    if (stat.type == FileSystemEntityType.FILE &&
+        fileEntity.path.startsWith(dirPathStr)) {
+      var map = {};
+      map['name'] = '/' + fileEntity.path.substring(dirPathStr.length);
+      map['size'] = stat.size;

[Cutch, 2016/07/01 21:23:17]

modification time might be useful here too

+      result.add(map);
+    }
+  }
+  return result;
+}
+
 _clearFuture(_) {
   serverFuture = null;
 }
 
 _onSignal(ProcessSignal signal) {
   if (serverFuture != null) {
     // Still waiting.
     return;
   }
   _lazyServerBoot();
@@ skipping 16 matching lines @@
   if (_isWindows) {
     // Cannot register for signals on Windows.
     return;
   }
   _signalSubscription = _signalWatch(ProcessSignal.SIGQUIT).listen(_onSignal);
 }
 
 main() {
   // Set embedder hooks.
   VMServiceEmbedderHooks.cleanup = cleanupCallback;
+  VMServiceEmbedderHooks.createTempDir = createTempDirCallback;
+  VMServiceEmbedderHooks.deleteDir = deleteDirCallback;
+  VMServiceEmbedderHooks.writeFile = writeFileCallback;
+  VMServiceEmbedderHooks.readFile = readFileCallback;
+  VMServiceEmbedderHooks.listFiles = listFilesCallback;
   // Always instantiate the vmservice object so that the exit message
   // can be delivered and waiting loaders can be cancelled.
   var service = new VMService();
   if (_autoStart) {
     _lazyServerBoot();
     server.startup();
     // It's just here to push an event on the event loop so that we invoke the
     // scheduled microtasks.
     Timer.run(() {});
   }
   scriptLoadPort.handler = _processLoadRequest;
   // Register signal handler after a small delay to avoid stalling main
   // isolate startup.
   _registerSignalHandlerTimer = new Timer(shortDelay, _registerSignalHandler);
   return scriptLoadPort;
 }
 
 _shutdown() native "VMServiceIO_Shutdown";