(hopefully) fix handling of remote UNC paths in OSFS

ChangeLog

@@ -44,9 +44,12 @@
       for wildcards.
     * Added listdirinfo method, which yields both the entry names and the
       corresponding info dicts in a single operation.
-    * Fixed operation of OSFS on win32 when it points to the root of a drive.
     * Made SubFS a subclass of WrapFS, and moved it into its own module at
       fs.wrapfs.subfs.
+    * Path-handling fixes for OSFS on win32:
+        * Work properly when pointing to the root of a drive.
+        * Better handling of remote UNC paths.
+        * Add ability to switch off use of long UNC paths.
     * OSFSWatchMixin improvements:
         * watch_inotify:  allow more than one watcher on a single path.
         * watch_win32:  don't create immortal reference cycles.
@@ -65,7 +68,8 @@
     * Added a getmmap to base
     * Added command line scripts fsls, fstree, fscat, fscp, fsmv
     * Added command line scripts fsmkdir, fsmount
-    * Made SFTP automatically pick up keys if no other authentication is available
+    * Made SFTP automatically pick up keys if no other authentication
+      is available
     * Optimized listdir and listdirinfo in SFTPFS
     * Made memoryfs work with threads
     * Added copyfile_non_atomic and movefile_non_atomic for improved performance of multi-threaded copies

fs/osfs/__init__.py

@@ -84,7 +84,7 @@ class OSFS(OSFSXAttrMixin, OSFSWatchMixin, FS):
               'atomic.setcontents' : False,
              }
 
-    def __init__(self, root_path, thread_synchronize=_thread_synchronize_default, encoding=None, create=False, dir_mode=0700):
+    def __init__(self, root_path, thread_synchronize=_thread_synchronize_default, encoding=None, create=False, dir_mode=0700, use_long_paths=True):
         """
         Creates an FS object that represents the OS Filesystem under a given root path
 
@@ -99,14 +99,18 @@ class OSFS(OSFSXAttrMixin, OSFSWatchMixin, FS):
         super(OSFS, self).__init__(thread_synchronize=thread_synchronize)
         self.encoding = encoding or sys.getfilesystemencoding()
         self.dir_mode = dir_mode
+        self.use_long_paths = use_long_paths
         root_path = os.path.expanduser(os.path.expandvars(root_path))
         root_path = os.path.normpath(os.path.abspath(root_path))
         #  Enable long pathnames on win32
         if sys.platform == "win32":
-            if not root_path.startswith("\\\\?\\"):
-                root_path = u"\\\\?\\" + root_path
+            if use_long_paths and not root_path.startswith("\\\\?\\"):
+                if not root_path.startswith("\\"):
+                   root_path = u"\\\\?\\" + root_path
+                else:
+                   root_path = u"\\\\?" + root_path
             #  If it points at the root of a drive, it needs a trailing slash.
-            if len(root_path) == 6:
+            if len(root_path) == 6 and not root_path.endswith("\\"):
                 root_path = root_path + "\\"
 
         if create: