- Add a shared AUFS utility lib and change both changes and streamlayerformat to use it

- Add UI for selecting whether to pull the tag, the repo, or the squashed tag

util/streamlayerformat.py

@@ -1,8 +1,8 @@
 import marisa_trie
 import os
 import tarfile
-import StringIO
-import traceback
+from aufs import is_aufs_metadata, get_deleted_prefix
+
 
 AUFS_METADATA = u'.wh..wh.'
 
@@ -70,19 +70,15 @@ class StreamLayerMerger(object):
 
   def process_tar_info(self, tar_info):
     absolute = os.path.relpath(tar_info.name.decode('utf-8'), './')
-    dirname = os.path.dirname(absolute)
-    filename = os.path.basename(absolute)
 
-    # Skip directories and metadata
-    if (filename.startswith(AUFS_METADATA) or
-        absolute.startswith(AUFS_METADATA)):
-      # Skip
+    # Skip metadata.
+    if is_aufs_metadata(absolute):
       return None
 
-    elif filename.startswith(AUFS_WHITEOUT):
-      removed_filename = filename[AUFS_WHITEOUT_PREFIX_LENGTH:]
-      removed_prefix = os.path.join('/', dirname, removed_filename)
-      self.encountered.append(removed_prefix)
+    # Add any prefix of deleted paths to the prefix list.
+    deleted_prefix = get_deleted_prefix(absolute)
+    if deleted_prefix is not None:
+      self.encountered.append(deleted_prefix)
       return None
 
     # Check if this file has already been encountered somewhere. If so,
@@ -90,10 +86,6 @@ class StreamLayerMerger(object):
     if unicode(absolute) in self.trie:
       return None
 
+    # Otherwise, add the path to the encountered list and return it.
     self.encountered.append(absolute)
-
-    if tar_info.isdir() or tar_info.issym() or tar_info.islnk():
-      return (tar_info, False)
-      
-    elif tar_info.isfile():
-      return (tar_info, True)
+    return (tar_info, tar_info.isfile() or tar_info.isdev())