Use a utils.TempDir() decorator for temporary files, to make sure we clean up even in case of excep…

tools/utils.py

 # 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.
 
 # This file contains a set of utilities functions used by other Python-based
 # scripts.
 
 import commands
 import os
 import platform
 import re
+import shutil
 import subprocess
 import sys
+import tempfile
 
 
 # Try to guess the host operating system.
 def GuessOS():
   id = platform.system()
   if id == "Linux":
     return "linux"
   elif id == "Darwin":
     return "macos"
   elif id == "Windows" or id == "Microsoft":
@@ skipping 375 matching lines @@
     return os.path.join(dart_binary_prefix, 'windows', 'dart.exe')
   else:
     return os.path.join(dart_binary_prefix, GuessOS(), 'dart')
 
 
 def DartSdkBinary():
   tools_dir = os.path.dirname(os.path.realpath(__file__))
   dart_binary_prefix = os.path.join(tools_dir, '..', 'sdk' , 'bin')
   return os.path.join(dart_binary_prefix, 'dart')
 
+class TempDir(object):
+  def __init__(self, prefix=''):
+    self._temp_dir = None
+    self._prefix = prefix
+
+  def __enter__(self):
+    self._temp_dir = tempfile.mkdtemp(self._prefix)
+    return self._temp_dir
+
+  def __exit__(self, *_):
+    shutil.rmtree(self._temp_dir, ignore_errors=True)
+
 
 if __name__ == "__main__":
   import sys
   Main(sys.argv)