Clean up the semantics of io.dart operations w.r.t. symlinks.

utils/pub/oauth2.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 oauth2;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:uri';
 
@@ skipping 48 matching lines @@
 final _scopes = ['https://www.googleapis.com/auth/userinfo.email'];
 
 /// An in-memory cache of the user's OAuth2 credentials. This should always be
 /// the same as the credentials file stored in the system cache.
 Credentials _credentials;
 
 /// Delete the cached credentials, if they exist.
 void clearCredentials(SystemCache cache) {
   _credentials = null;
   var credentialsFile = _credentialsFile(cache);
-  if (!fileExists(credentialsFile)) return;
-
-  deleteFile(credentialsFile);
+  if (entryExists(credentialsFile)) deleteEntry(credentialsFile);

[Bob Nystrom, 2013/03/27 20:10:09]

Why entryExists here?

[nweiz, 2013/03/27 20:36:29]

If, through some weird fluke or user craziness, "credentials.json" is a
directory or broken symlink, we don't want that to break pub.

 }
 
 /// Asynchronously passes an OAuth2 [Client] to [fn], and closes the client when
 /// the [Future] returned by [fn] completes.
 ///
 /// This takes care of loading and saving the client's credentials, as well as
 /// prompting the user for their authorization. It will also re-authorize and
 /// re-run [fn] if a recoverable authorization error is detected.
 Future withClient(SystemCache cache, Future fn(Client client)) {
   return _getClient(cache).then((client) {
@@ skipping 118 matching lines @@
         response.statusCode = 404;
         response.close();
       }
     });
   })
   .then((client) {
     log.message('Successfully authorized.\n');
     return client;
   });
 }