Fix use of Process API in pub.

utils/pub/io.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.
 
 /**
  * Helper functionality to make working with IO easier.
  */
 #library('io');
 
 #import('dart:io');
@@ skipping 363 matching lines @@
   };
 
   connection.onResponse = (response) {
     if (response.statusCode >= 400) {
       client.shutdown();
       completer.completeException(
           new HttpException(response.statusCode, response.reasonPhrase));
       return;
     }
 
-    // TODO(nweiz): remove this extra pipe when issue 4974 is fixed.
-    var sink = new ListInputStream();
-    pipeInputToInput(response.inputStream, sink);
-    completer.complete(sink);
+    completer.complete(response.inputStream);
   };
 
   return completer.future;
 }
 
 /**
  * Opens an input stream for a HTTP GET request to [uri], which may be a
  * [String] or [Uri]. Completes with the result of the request as a String.
  */
 Future<String> httpGetString(uri) {
@@ skipping 181 matching lines @@
 
 /**
  * Extracts a `.tar.gz` file from [stream] to [destination], which can be a
  * directory or a path. Returns whether or not the extraction was successful.
  */
 Future<bool> extractTarGz(InputStream stream, destination) {
   var process = Process.start("tar",
       ["--extract", "--gunzip", "--directory", _getPath(destination)]);
   var completer = new Completer<int>();
 
-  stream.pipe(process.stdin);
-  process.stdout.pipe(stdout, close: false);
-  process.stderr.pipe(stderr, close: false);
+  // Wait for the process to be fully started before writing to its
+  // stdin stream.
+  process.onStart = () {
+    stream.pipe(process.stdin);
+    process.stdout.pipe(stdout, close: false);
+    process.stderr.pipe(stderr, close: false);
 
-  process.onExit = completer.complete;
-  process.onError = completer.completeException;
+    process.onExit = completer.complete;
+    process.onError = completer.completeException;

[nweiz, 2012/09/19 18:09:45]

What happens if "tar" isn't found? Will onStart fire, then onError? If not, the
completer will never fire.

[Mads Ager (google), 2012/09/20 06:16:26]

Good catch, thanks! If the executable is not found only 'onError' will fire.
I'll move the onError and onExit handler registration out of onStart and commit
separately.

+  };
+
   return completer.future.transform((exitCode) => exitCode == 0);
 }
 
 /**
  * Exception thrown when an HTTP operation fails.
  */
 class HttpException implements Exception {
   final int statusCode;
   final String reason;
 
@@ skipping 43 matching lines @@
   return new Directory(entry);
 }
 
 /**
  * Gets a [Uri] for [uri], which can either already be one, or be a [String].
  */
 Uri _getUri(uri) {
   if (uri is Uri) return uri;
   return new Uri.fromString(uri);
 }