Use relative symlinks for self links and secondary "packages" dirs.

This lets you move a package directory without breaking all of those links.
BUG=http://code.google.com/p/dart/issues/detail?id=8342

Review URL: https://codereview.chromium.org//12321020

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@18785 260f80e4-7a28-3924-810f-c04153c831b5

lib/src/entrypoint.dart

@@ -232,7 +232,7 @@ class Entrypoint {
       if (entryExists(linkPath)) return;
       ensureDir(packagesDir);
       return createPackageSymlink(root.name, root.dir, linkPath,
-          isSelfLink: true);
+          isSelfLink: true, relative: true);
     });
   }
 
@@ -296,7 +296,7 @@ class Entrypoint {
     return defer(() {
       var symlink = path.join(dir, 'packages');
       if (entryExists(symlink)) return;
-      return createSymlink(packagesDir, symlink);
+      return createSymlink(packagesDir, symlink, relative: true);
     });
   }
 }

test/install/pub_install_test.dart

@@ -10,6 +10,8 @@ import '../../../../pkg/unittest/lib/unittest.dart';
 import '../test_pub.dart';
 
 main() {
+  initConfig();
+
   group('requires', () {
     integration('a pubspec', () {
       dir(appPath, []).scheduleCreate();

test/install/relative_symlink_test.dart

+// 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.
+
+library pub_tests;
+
+import 'dart:io';
+
+import '../../../../pkg/unittest/lib/unittest.dart';
+import '../test_pub.dart';
+
+main() {
+  // Pub uses NTFS junction points to create links in the packages directory.
+  // These (unlike the symlinks that are supported in Vista and later) do not
+  // support relative paths. So this test, by design, will not pass on Windows.
+  // So just skip it.
+  if (Platform.operatingSystem == "windows") return;
+
+  initConfig();
+  integration('uses a relative symlink for the self link', () {
+    dir(appPath, [
+      appPubspec([]),
+      libDir('foo')
+    ]).scheduleCreate();
+
+    schedulePub(args: ['install'],
+        output: new RegExp(r"Dependencies installed!$"));
+
+    scheduleRename(appPath, "moved");
+
+    dir("moved", [
+      dir("packages", [
+        dir("myapp", [
+          file('foo.dart', 'main() => "foo";')
+        ])
+      ])
+    ]).scheduleValidate();
+  });
+
+  integration('uses a relative symlink for secondary packages directory', () {
+    dir(appPath, [
+      appPubspec([]),
+      libDir('foo'),
+      dir("bin")
+    ]).scheduleCreate();
+
+    schedulePub(args: ['install'],
+        output: new RegExp(r"Dependencies installed!$"));
+
+    scheduleRename(appPath, "moved");
+
+    dir("moved", [
+      dir("bin", [
+        dir("packages", [
+          dir("myapp", [
+            file('foo.dart', 'main() => "foo";')
+          ])
+        ])
+      ])
+    ]).scheduleValidate();
+  });
+}