Checking folder/file ntfs permissions using python

Question

As the question title might suggest, I would very much like to know of the way to check the ntfs permissions of the given file or folder (hint: those are the ones you see in the "security" tab). Basically, what I need is to take a path to a file or directory (on a local machine, or, preferrably, on a share on a remote machine) and get the list of users/groups and the corresponding permissions for this file/folder. Ultimately, the application is going to traverse a directory tree, reading permissions for each object and processing them accordingly.

Now, I can think of a number of ways to do that:

• parse cacls.exe output -- easily done, BUT, unless im missing something, cacls.exe only gives the permissions in the form of R|W|C|F (read/write/change/full), which is insufficient (I need to get the permissions like "List folder contents", extended permissions too)
• xcacls.exe or xcacls.vbs output -- yes, they give me all the permissions I need, but they work dreadfully slow, it takes xcacls.vbs about ONE SECOND to get permissions on a local system file. Such speed is unacceptable
• win32security (it wraps around winapi, right?) -- I am sure it can be handled like this, but I'd rather not reinvent the wheel

Is there anything else I am missing here?

Answer 1

Unless you fancy rolling your own, win32security is the way to go. There's the beginnings of an example here:

http://timgolden.me.uk/python/win32_how_do_i/get-the-owner-of-a-file.html

If you want to live slightly dangerously (!) my in-progress winsys package is designed to do exactly what you're after. You can get an MSI of the dev version here:

http://timgolden.me.uk/python/downloads/WinSys-0.4.win32-py2.6.msi

or you can just checkout the svn trunk:

svn co http://winsys.googlecode.com/svn/trunk winsys

To do what you describe (guessing slightly at the exact requirements) you could do this:

import codecs
from winsys import fs

base = "c:/temp"
with codecs.open ("permissions.log", "wb", encoding="utf8") as log:
  for f in fs.flat (base):
  log.write ("\n" + f.filepath.relative_to (base) + "\n")
  for ace in f.security ().dacl:
    access_flags = fs.FILE_ACCESS.names_from_value (ace.access)
    log.write (u"  %s => %s\n" % (ace.trustee, ", ".join (access_flags)))

TJG