os.access() under windows

[Tim Golden]

Yann Leboulanger wrote:
> Martin v. Löwis a écrit :
>>> I create a folder test under e:
>>>
>>> then os.access('e:\\test', os.W_OK) returns True. Everything's ok.
>>>
>>> Now I move My Documents to this e:\test folder
>>>
>>> Then os.access('e:\\test', os.W_OK) returns False !!
>> This description is, unfortunately, too imprecise to allow reproducing
>> that effect. What precisely do you mean by "I move My Documents to
>> this e:\test folder"?
>>
> 
> 
> I Right click on "My Documents" folder, and change the path to e:\test 
> there.
> So that "My documents" folder points to e:\test

Python uses the GetFileAttributesW API call to determine
access to the path you pass in. It then tests the return
against the FILE_ATTRIBUTE_READONLY flag and returns False
if you asked for Write and the Readonly flag is set.

The problem seems to be twofold: whereas a normal directory
(such as e:\temp) will not usually have its readonly flag set,
on a special directory such as the My Documents folder the flag
seems to be set by the system; also, the READONLY flag on a
directory refers to its deleteability, not to its writeablility.
At least, according to:

http://msdn2.microsoft.com/en-us/library/aa364944.aspx

I suspect this constitutes a bug in os.access which
should do some more interpretation of the results. But
no doubt Martin von L can comment with more authority
than I on this one.

TJG