Clean up code that locates SDK and SDK version.

utils/pub/sdk.dart

Index: utils/pub/sdk.dart
diff --git a/utils/pub/sdk.dart b/utils/pub/sdk.dart
new file mode 100644
index 0000000000000000000000000000000000000000..f8db76c173ca4c1a0dc2090b8ae178d5c9ccd560
--- /dev/null
+++ b/utils/pub/sdk.dart
@@ -0,0 +1,38 @@
+// Copyright (c) 2012, 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.
+
+/// Operations relative to the user's installed Dart SDK.
+library sdk;
+
+import 'dart:io';
+
+import '../../pkg/path/lib/path.dart' as path;
+import 'log.dart' as log;
+import 'version.dart';
+
+/// Gets the path to the root directory of the SDK.
+String get rootDirectory {
+  // If the environment variable was provided, use it. This is mainly used for
+  // the pub tests.
+  var dir = Platform.environment["DART_SDK"];
+  if (dir != null) {
+    log.fine("Using DART_SDK to find SDK at $dir");
+    return dir;
+  }
+
+  var pubDir = path.dirname(new Options().script);
+  dir = path.normalize(path.join(pubDir, "../../"));
+  log.fine("Located SDK at $dir");
+  return dir;
+}
+
+/// Gets the SDK's revision number formatted to be a semantic version.
+Version version = _getVersion();
+
+/// Determine the SDK revision number.
+Version _getVersion() {
+  var revisionPath = path.join(rootDirectory, "revision");
+  var revision = new File(revisionPath).readAsStringSync();
+  return new Version.parse("0.0.0-r.${revision.trim()}");
+}