Support some file operations in dart:io under mojo

mojo/dart/embedder/io/file_patch.dart

Index: mojo/dart/embedder/io/file_patch.dart
diff --git a/mojo/dart/embedder/io/file_patch.dart b/mojo/dart/embedder/io/file_patch.dart
index 73767a1b01552562c19d0b65ece4f7304d934bb2..3de76e3bde092c9eab8cee90c83457f5d44f08cf 100644
--- a/mojo/dart/embedder/io/file_patch.dart
+++ b/mojo/dart/embedder/io/file_patch.dart
@@ -2,8 +2,283 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:_mojo_services/mojo/files/types.mojom.dart' as types;
+
 //
-// Implementation of File and RandomAccessFile for Mojo.
+// Implementation of Directory, File, and RandomAccessFile for Mojo.
 //
 
-// TODO(johnmccutchan): Implement.
+OSError _OSErrorFromError(types.Error error) {
+  assert(error != null);
+  return new OSError(error.toString(), error.toJson());
+}
+
+String _ensurePathIsRelative(String path) {
+  while (path.startsWith('/')) {
+    // Trim off the leading '/'.
+    path = path.substring(1);
+  }
+  return path;
+}
+
+patch class _Directory {
+  // We start at the root of the file system.
+  static String _currentDirectoryPath = '/';
+
+  /* patch */ Future<Directory> create({bool recursive: false}) async {
+    if (recursive) {
+      return exists().then((exists) {
+        if (exists) return this;
+        if (path != parent.path) {
+          return parent.create(recursive: true).then((_) {
+            return create();
+          });
+        } else {
+          return create();
+        }
+      });
+    }
+    DirectoryProxy rootDirectory = await _getRootDirectory();
+    int flags =
+        types.kOpenFlagRead | types.kOpenFlagWrite | types.kOpenFlagCreate;
+    var response =
+        await rootDirectory.responseOrError(
+            rootDirectory.ptr.openDirectory(_ensurePathIsRelative(path),
+                                            null,
+                                            flags));
+    if (response.error != types.Error.ok) {
+      throw _OSErrorFromError(response.error);
+    }
+    return this;
+  }
+
+  /* patch */ Future<Directory> createTemp([String prefix]) async {
+    DirectoryProxy rootDirectory = await _getRootDirectory();
+    // Create directory and fail if it already exists.
+    int flags = types.kOpenFlagRead | types.kOpenFlagWrite |
+                types.kOpenFlagCreate | types.kOpenFlagExclusive;
+    String tempPath = '$path/$prefix';
+    while (true) {
+      var response =
+          await rootDirectory.responseOrError(
+              rootDirectory.ptr.openDirectory(tempPath, null, flags));
+      if (response.error == types.Error.ok) {
+        // Success.
+        break;
+      }
+      // Alter the path and try again.
+      // TODO(johnmccutchan): Append a randomly generated character.
+      tempPath = tempPath + 'a';
+    }
+    return new Directory(tempPath);
+  }
+
+  /* patch */ Future<bool> exists() async {
+    DirectoryProxy rootDirectory = await _getRootDirectory();
+    int flags = types.kOpenFlagRead | types.kOpenFlagWrite;
+    var response =
+        await await rootDirectory.responseOrError(
+            rootDirectory.ptr.openDirectory(_ensurePathIsRelative(path),
+                                            null,
+                                            flags));
+    // If we can open it, it exists.
+    return response.error == types.Error.ok;
+  }
+
+  /* patch */ static _current() {
+    return _currentDirectoryPath;
+  }
+
+  /* patch */ static _setCurrent(path) {
+    _currentDirectoryPath = path;
+  }
+
+  /* patch */ static _createTemp(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static String _systemTemp() {
+    return 'tmp';
+  }
+
+  /* patch */ static _exists(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _create(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _deleteNative(String path, bool recursive) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _rename(String path, String newPath) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static List _list(String path, bool recursive, bool followLinks) {
+    throw new UnimplementedError();
+  }
+}
+
+
+patch class _File {
+  /* patch */ Future<bool> exists() async {
+    DirectoryProxy rootDirectory = await _getRootDirectory();
+    int flags = types.kOpenFlagRead;
+    var response =
+        await rootDirectory.responseOrError(
+            rootDirectory.ptr.openFile(_ensurePathIsRelative(path),
+                                       null,
+                                       flags));
+    // If we can open it, it exists.
+    return response.error == types.Error.ok;
+  }
+
+  Future<File> create({bool recursive: false}) async {
+    if (recursive) {
+      // Create any parent directories.
+      await parent.create(recursive: true);
+    }
+    DirectoryProxy rootDirectory = await _getRootDirectory();
+    int flags = types.kOpenFlagWrite | types.kOpenFlagCreate;
+    var response =
+        await rootDirectory.responseOrError(
+            rootDirectory.ptr.openFile(_ensurePathIsRelative(path),
+                                       null,
+                                       flags));
+    if (response.error != types.Error.ok) {
+      throw _OSErrorFromError(response.error);
+    }
+    return this;
+  }
+
+  /* patch */ static _exists(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _create(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _createLink(String path, String target) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _linkTarget(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _deleteNative(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _deleteLinkNative(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _rename(String oldPath, String newPath) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _renameLink(String oldPath, String newPath) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _copy(String oldPath, String newPath) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _lengthFromPath(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _lastModified(String path) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _open(String path, int mode) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static int _openStdio(int fd) {
+    throw new UnimplementedError();
+  }
+}
+
+patch class FileStat {
+  /* patch */ static _statSync(String path) {
+  }
+}
+
+
+patch class FileSystemEntity {
+  /* patch */ static _getType(String path, bool followLinks) {
+    throw new UnimplementedError();
+  }
+  /* patch */ static _identical(String path1, String path2) {
+    throw new UnimplementedError();
+  }
+  /* patch */ static _resolveSymbolicLinks(String path) {
+    throw new UnimplementedError();
+  }
+}
+
+patch class _Link {
+}
+
+
+patch class _RandomAccessFile {
+  /* patch */ static int _close(int id) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static int _getFD(int id) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _readByte(int id) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _read(int id, int bytes) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _readInto(int id, List<int> buffer, int start, int end) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _writeByte(int id, int value) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _writeFrom(int id, List<int> buffer, int start, int end) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _position(int id) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _setPosition(int id, int position) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _truncate(int id, int length) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _length(int id) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _flush(int id) {
+    throw new UnimplementedError();
+  }
+
+  /* patch */ static _lock(int id, int lock, int start, int end) {
+    throw new UnimplementedError();
+  }
+}