Add tools script to update homebrew, the MacOS SDK updating solution.

tools/apps/update_homebrew/bin/update_homebrew.dart

+// Copyright (c) 2014, 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 update_repo;
+
+import 'dart:io';
+import 'dart:convert';
+import 'dart:async';
+import 'package:http/http.dart' as http;
+import 'package:args/args.dart';
+import 'package:googleapis/storage/v1.dart' as storage;
+import 'package:googleapis/common/common.dart' show DownloadOptions, Media;
+
+String repository;  // The path to the temporary git checkout of dart-homebrew.
+Map gitEnvironment;  // Pass a wrapper script for SSH to git in the environment.
+
+void check(String message, bool condition) {
+  if (!condition) {
+    print(message);
+    exit(1);
+  }
+}
+
+int firstIndexWhere(List l, bool test(e)) {
+  for (int i = 0; i < l.length; ++i) {
+    if (test(l[i])) return i;
+  }
+  return -1;
+}
+
+Future<String> getHash256(String channel, int revision, String download) {
+  var client = new http.Client();
+  var api = new storage.StorageApi(client);
+  return
+      api.objects.get('dart-archive',
+                      'channels/$channel/release/$revision/$download.sha256sum',
+                       downloadOptions: DownloadOptions.FullMedia)
+      .then((Media media) => ASCII.decodeStream(media.stream))
+      .whenComplete(client.close);
+}
+
+Future<String> getVersion(String channel, int revision) {
+  var client = new http.Client();
+  var api = new storage.StorageApi(client);
+  return api.objects.get('dart-archive',
+                         'channels/$channel/release/$revision/VERSION',
+                         downloadOptions: DownloadOptions.FullMedia)
+      .then((Media media) => JSON.fuse(ASCII).decoder.bind(media.stream).first)
+      .then((versionObject) => versionObject['version'])
+      .whenComplete(client.close);
+}
+
+Future modifyHomebrewFormulas(String channel, int revision) {

[Søren Gjesse, 2014/09/26 08:55:00]

Wouldn't it be easier to have the full Ruby source code for the formulas in here
instead of modifying what is in the repro? Seems less error-prone.

+  // Read script to lines, from file
+  Future<List<String>> getLines(String filename) {
+    final file = new File('$repository/$filename');
+    final lines = ASCII.decoder.fuse(new LineSplitter()).bind(file.openRead());
+    return lines.toList();
+  }
+
+  // Modify url, sha256, version lines
+  Future<List<String>> modifyLines(List<String> lines, String download) {
+    final int pos = firstIndexWhere(lines, (line) => line.contains(
+        "url 'https://storage.googleapis.com/dart-archive/channels/$channel")
+        && line.contains(download));
+    check("URL line not found", pos >= 0);
+    check("Version line not found", lines[pos - 1].contains("version '"));
+    check("sha256 line not found", lines[pos + 1].contains("sha256 '"));
+
+    final indent = new RegExp('^\\s*').stringMatch(lines[pos]);
+    lines[pos] =
+        "${indent}url 'https://storage.googleapis.com/dart-archive/channels/"
+        "$channel/release/$revision/$download'";
+    return getHash256(channel, revision, download)
+        .then((hashLine) {
+          final hash = new RegExp('[0-9a-fA-F]*').stringMatch(hashLine);
+          lines[pos + 1] = "${indent}sha256 '$hash'";
+        })
+        .then((_) => getVersion(channel, revision))
+        .then((version) {
+          lines[pos - 1] = "${indent}version '$version'";
+          return lines;
+        });
+  }
+
+  Future saveLines(List<String> lines, String filename) {
+    final file = new File('$repository/$filename');
+    return (file.openWrite()..writeAll(lines, '\n')..write('\n')).close();
+  }
+
+  // Write lines to file
+  return getLines('dartium.rb')
+      .then((lines) =>
+          modifyLines(lines, 'dartium/dartium-macos-ia32-release.zip'))
+      .then((lines) => saveLines(lines, 'dartium.rb'))
+      .then((_) => getLines('dart.rb'))
+      .then((lines) => modifyLines(lines, 'sdk/dartsdk-macos-x64-release.zip'))
+      .then((lines) => modifyLines(lines, 'sdk/dartsdk-macos-ia32-release.zip'))
+      .then((lines) => saveLines(lines, 'dart.rb'));
+}
+
+Future runGit(List<String> args) {
+  print("git ${args.join(' ')}");
+  return Process.run('git', args, workingDirectory: repository,
+                     environment: gitEnvironment)
+      .then((result) {
+        print(result.stdout);
+        print(result.stderr);
+      });
+}
+
+main(args) {
+  final parser = new ArgParser()
+      ..addOption('revision', abbr: 'r')
+      ..addOption('channel', abbr: 'c', allowed: ['dev', 'stable'])
+      ..addOption('key', abbr: 'k');
+  final options = parser.parse(args);
+  final revision = options['revision'];
+  final channel = options['channel'];
+  final sshWrapper = Platform.script.resolve('ssh_with_key').toFilePath();
+  gitEnvironment = {'GIT_SSH': sshWrapper,
+                    'SSH_KEY_PATH': options['key']};
+
+  Directory.systemTemp.createTemp('update_homebrew')
+      .then((tempDir) {
+        repository = tempDir.path;
+      })
+      .then((_) => runGit(
+          ['clone', 'git@github.com:dart-lang/homebrew-dart.git', '.']))
+      .then((_) => modifyHomebrewFormulas(channel, revision))
+      .then((_) => runGit(['commit', '-a', '-m',
+                           'Updated $channel branch to revision $revision']))
+      .then((_) => runGit(['push']))
+      .whenComplete(() => new Directory(repository).delete(recursive: true));
+}