[Tutor] os.rename() on Win 98

[Francois Granger]

I got serious difficulties with something apparently  simple. so I 
simplified it to trace it back as follow.

I have the following script:

=================================================Start
def saveWithBackup(data, fileName, backup = 2):
     import os
     dir,file = os.path.split(fileName)
     parts = file.split('.')
     i = 0
     #filebak = os.path.join(dir, '.'.join(parts[0:-1]) + '.bak')
     filebak = os.path.join(dir, 
parts[0]+str(i)+'.'+'.'.join(parts[1:-1])+'.bak')
     os.rename(fileName, filebak)

fileName = 'default.fr.txt'
fp = open(fileName)
data = fp.read()
fp.close
result = saveWithBackup(data, fileName, backup = 2)
print result
=================================================End

It runs fine on a Mac with MacOS 9

I run it on Windows 98: transcript of the dos session follows.

=================================================Start
C:\toto>dir

  Le volume dans le lecteur C est REALPC
  Le numÈro de sÈrie du volume est F400-4086
  RÈpertoire de C:\toto

.              <REP>        26/07/02  17:00 .
..             <REP>        26/07/02  17:00 ..
DEFAUL~1 BAK        16 908  26/07/02  11:19 default.fr.bak
DEFAUL~1 TXT        16 908  26/07/02  11:27 default.fr.txt
SAVE     PY          1 456  26/07/02  16:44 save.py
SAVE1    PY            474  26/07/02  17:14 save1.py
          4 fichier(s)             35 746 octets
          2 rÈpertoire(s)     690 978 816 octets libres

C:\toto>c:\Python22\python save1.py
Traceback (most recent call last):
   File "save1.py", line 14, in ?
     result = saveWithBackup(data, fileName, backup = 2)
   File "save1.py", line 8, in saveWithBackup
     os.rename(fileName, filebak)
OSError: [Errno 13] Permission denied

C:\toto>
=================================================End

Not understanding what is happening, I created a simple brute force 
rename wich works.

def rename(a,b):
     data = open(a, 'rb').read()
     open(b, 'wb').write(data)

My guess is that os.rename() does not handle properly the long name 
to short name under W98 because the filebak name I creat would 
produce the same short name as the one already existing ?????