[Python-Dev] os.path.exists() / os.path.isdir() inconsistency when dealing with gvfs directories

[Giampaolo Rodolà]

I've just noticed a strange behavior when dealing with gvfs filesystems:

giampaolo at ubuntu:~$ python -c "import os;
print(os.path.exists('/home/giampaolo/.gvfs'))"
True
giampaolo at ubuntu:~$ sudo su
root at ubuntu:~# python -c "import os;
print(os.path.exists('/home/giampaolo/.gvfs'))"
False

This is due to os.stat() which internally fails with PermissionError (EACCES).
The same problem exists with os.path.isdir() which will return True as
limited user and False as root.
I'm not sure what's best to do here nor I know if there are other
cases other than when dealing with gvfs which can produce similar
behaviors but here's an idea:

- make os.path.exists() return True in case of PermissionError because
that's supposed to mean there's an existing path to deny access to

- fix isdir(), islink(), isfile() documentation pointing out that in
case of EACCES/EPERM or when dealing with exotic paths/fs it may
return incorrect results.

Comments?

--- Giampaolo
http://code.google.com/p/pyftpdlib/
http://code.google.com/p/psutil/
http://code.google.com/p/pysendfile/