Rename file if it exists.

Stephen Reese rsreese at gmail.com
Fri Oct 16 23:08:51 CEST 2009


> This isn't working because the else: is dangling. And I think your logic is
> flawed (I might be wrong of course) because you rename the *existing* file
> instead of giving the new one a new data.
>
> Thus e.g. a link to the file (if it's a webserver) will suddenly deliver a
> different file. I doubt that's what you wanted. And you also can only upload
> one file per *day*. Which doesn't sound good to me. You should disambiguate
> further. And if it's ok to append a date, I suggest you do that always.
>
> So instead, the logic should be something like this:
>
> import datetime
>
> basename = ... # however you get to that
>
> basename = basename + "_" + datetime.datetime.now().strftime("%Y-%m-%d")
>
> count = 0
> filename = basename
> while os.path.isfile(filename):
>    filename = basename + "." + count
>    count += 1
>
>
> Diez

Diez,

Ahh that would be much easier to just date the file upon upload. My
initial concern was that renaming the file would alter the hash value,
obviously I didn't think this one through too well.

I adjusted the code and tried to incorporate your recommendation but
still no go. Anything else obviously wrong with the following snippet?

Thanks


# Test if the file was uploaded
if fileitem.filename:

   # strip leading path from file name to avoid directory traversal attacks
   fn = os.path.basename(fileitem.filename)

   # Include date in filename.
   basename = fn
   basename = basename + "_" + datetime.datetime.now().strftime("%Y-%m-%d")
   count = 0
   fn = basename
   while os.path.isfile(fn):
      fn = basename + "." + count
      count += 1

   # Open file for writing
   f = open('/var/www/dropbox/' + fn, 'wb', 10000)
   h = hashlib.md5()
   datalength = 0

   # Read the file in chunks
   for chunk in fbuffer(fileitem.file):
      f.write(chunk)
      h.update(chunk)
      datalength += len(chunk)
   hexdigest = h.hexdigest()
   f.close()

   message = 'The file "' + fn + '" was uploaded successfully with a
MD5 hash value of ' + hexdigest + ', click <a href="#">here</a> to go
back.'



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