Using the fs module

Take ownership of a file

Take ownership of a file to which you have no other access.

from __future__ import with_statement
from winsys import security, fs

f = fs.file ("c:/temp/tim.txt")
with security.change_privileges ([security.PRIVILEGE.TAKE_OWNERSHIP]):
  f.take_ownership ()

assert f.security ("O").owner == security.me ()

The Entry.take_ownership() method assumes that you have no existing access to the object, so does not attempt to read its security at all since this would probably fail. If you do not even have permission to set the owner entry in the security descriptor you need to enable the SeTakeOwnership privilege in your token. Best practice is to enable privileges for only as long as you need them, so the security.changed_privileges() is a context manager which reverses the privilege changes once it exits.

Find the sizes of top-level directories

For a given root directory, find the total size taken by all the files in each of its top-level subdirectories, and display them in descending order of size.

import operator
from winsys import dialogs, fs, utils

[root] = dialogs.dialog (
  "Find top-level sizes",
  ("Start from", "", dialogs.get_folder)
)

sizes = dict (
  (d, sum (f.size for f in d.flat ())) 
    for d in fs.dir (root).dirs ()
)
for d, size in sorted (sizes.items (), key=operator.itemgetter (1), reverse=True):
  print d.name, "=>", utils.size_as_mb (size)

The dialogs.dialog() function sets up a simple dialog box requesting the name of the root directory (offering a push-button for a standard selection dialog). Then the Dir.dirs() method iterates over all subdirectories of its directory, and Dir.flat() iterates over all the files underneath a directory from which we can fetch their (compressed) size and sum them all up.

The rest is mostly standard Python gimmickry with sorting dictionaries etc. utils.size_as_mb() provides a more human-readable version of a number of bytes.