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Mon Nov 10 16:30:12 EST 2003 · https://mail.python.org/pipermail/python-dev/2003-November/040158.html

> > Sounds like a good suggestion; I'll see if I can check something in.
> The fix is trivial (IMHO). A patch is attached.

Now there you are wrong, my friend. :-)

> > (However, given that there already exists an attack on this function,
> > does fixing this actually make any difference?)
> Not really, but it is defensive programming (since the module is
> security-oriented). Maybe you want a non-existent name for a block
> device or a pipe (which mkstemp doesn't provide).

I use it all the time for situations where I have to name a file that
an external program is going to create for me.

> I happened to look into the module to see if I can replace some
> hand-written functions with the ones in the module and I saw that
> mktemp() could be improved maybe.
> 
> Regards,
> Iustin Pop
> 
> --zhXaljGHf11kAtnf
> Content-Type: text/plain; charset=us-ascii
> Content-Disposition: attachment; filename="tempfile.patch"
> 
> diff -urN old/tempfile.py new/tempfile.py
> --- old/tempfile.py	2003-11-10 23:07:46.000000000 +0200
> +++ new/tempfile.py	2003-11-10 23:22:57.000000000 +0200
> @@ -338,7 +338,9 @@
>      for seq in xrange(TMP_MAX):
>          name = names.next()
>          file = _os.path.join(dir, prefix + name + suffix)
> -        if not _os.path.exists(file):
> +        try:
> +            _os.lstat(file)
> +        except _os.error:
>              return file
>  
>      raise IOError, (_errno.EEXIST, "No usable temporary filename found")

This fix would break on non-Unix platforms (the module should work
everywhere).  Fortunately I already checked something in that *does*
work across platforms. :-)

--Guido van Rossum (home page: http://www.python.org/~guido/)

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[Python-Dev] tempfile.mktemp and os.path.exists