predict directory write permission under windows?

[Qiangning Hong]

I want to know if I can write files into a directory before I actually 
perferm the write behavor.  I found os.access(path, os.W_OK) but it uses 
real uid/gid to check instead of euid/egid so it doesn't fit my problem.

I don't know how to get euid/egid under windows so I cannot use the mode 
infomation returned by os.stat().

Anybody give me a hint?