@@ -15,7 +15,7 @@
 import os
 import stat
 from git.objects import Blob, Tree
-from git.utils import SHA1Writer, LazyMixin
+from git.utils import SHA1Writer, LazyMixin, ConcurrentWriteOperation
 from git.diff import Diffable
 
 class _TemporaryFileSwap(object):
@@ -175,7 +175,7 @@ def __init__(self, repo, stream = None):
 	def _set_cache_(self, attr):
 		if attr == "entries":
 			# read the current index
-			fp = open(os.path.join(self.repo.path, "index"), "r")
+			fp = open(self._index_path(), "r")
 			try:
 				self._read_from_stream(fp)
 			finally:
@@ -184,6 +184,9 @@ def _set_cache_(self, attr):
 		else:
 			super(Index, self)._set_cache_(attr)
 
+	def _index_path(self):
+		return os.path.join(self.repo.path, "index")
+	
 	@classmethod
 	def _read_entry(cls, stream):
 		"""Return: One entry of the given stream"""
@@ -306,19 +309,28 @@ def _write_cache_entry(cls, stream, entry):
 		real_size = ((stream.tell() - beginoffset + 8) & ~7)
 		stream.write("\0" * ((beginoffset + real_size) - stream.tell()))
 
-	def write(self, stream):
+	def write(self, stream=None):
 		"""
-		Write the current state to the given stream
+		Write the current state to the given stream or to the default repository 
+		index.
 		
 		``stream``
-			File-like object.
+			File-like object or None.
+			If None, the default repository index will be overwritten.
 		
 		Returns
 			self
 		
 		Note
 			Index writing based on the dulwich implementation
 		"""
+		write_op = None
+		if stream is None:
+			write_op = ConcurrentWriteOperation(self._index_path())
+			stream = write_op._begin_writing()
+			# stream = open(self._index_path()
+		# END stream handling 
+		
 		stream = SHA1Writer(stream)
 
 		# header
@@ -338,6 +350,9 @@ def write(self, stream):
 		# write the sha over the content
 		stream.write_sha()
 
+		if write_op is not None:
+			write_op._end_writing()
+			
 
 	@classmethod
 	def from_tree(cls, repo, *treeish, **kwargs):
@@ -504,7 +519,7 @@ def write_tree(self):
 		Returns
 			Tree object representing this index
 		"""
-		index_path = os.path.join(self.repo.path, "index")
+		index_path = self._index_path()
 		tmp_index_mover = _TemporaryFileSwap(index_path)
 
 		self.to_file(self, index_path)
 
@@ -201,7 +201,9 @@ def _end_writing(self, successful=True):
 		if self._temp_write_fp is None:
 			return 
 
-		self._temp_write_fp.close()
+		if not self._temp_write_fp.closed:
+			self._temp_write_fp.close()
+		
 		if successful:
 			# on windows, rename does not silently overwrite the existing one
 			if sys.platform == "win32":
 
@@ -101,7 +101,13 @@ def test_from_tree(self):
 		# END for each blob
 		assert num_blobs == len(three_way_index.entries)
 
-	def test_from_index(self):
+	@with_rw_repo('0.1.6')
+	def test_from_index(self, rw_repo):
 		# default Index instance points to our index
-		index = Index(self.rorepo)
+		index = Index(rw_repo)
 		assert len(index.entries)
+		
+		# write the file back
+		index.write()
+		
+		# could sha it, or check stats