Create tar files in a cross-platform format.

lib/src/io.dart

 // Copyright (c) 2013, 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.
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 986 matching lines @@
     contents = contents.map((entry) {
       entry = path.absolute(entry);
       if (!path.isWithin(baseDir, entry)) {
         throw new ArgumentError('Entry $entry is not inside $baseDir.');
       }
       return path.relative(entry, from: baseDir);
     }).toList();
 
     if (Platform.operatingSystem != "windows") {
       var args = [
+        // ustar is the most recent tar format that's compatible across all
+        // OSes.
+        "--format=ustar",
         "--create",
         "--gzip",
         "--directory",
         baseDir,
         "--files-from",
         "/dev/stdin"
       ];
 
       var process = await startProcess("tar", args);
       process.stdin.add(UTF8.encode(contents.join("\n")));
@@ skipping 46 matching lines @@
 
   // TODO(rnystrom): Remove this and change to returning one string.
   static List<String> _toLines(String output) {
     var lines = splitLines(output);
     if (!lines.isEmpty && lines.last == "") lines.removeLast();
     return lines;
   }
 
   bool get success => exitCode == exit_codes.SUCCESS;
 }