ValueError: insecure string pickle

Question

When I am trying to load something I dumped using cPickle, I get the error message:

ValueError: insecure string pickle

Both the dumping and

Answer 1

I ran into this earlier, found this thread, and assumed that I was immune to the file closing issue mentioned in a couple of these answers since I was using a with statement:

with tempfile.NamedTemporaryFile(mode='wb') as temp_file:
    pickle.dump(foo, temp_file)

    # Push file to another machine
    _send_file(temp_file.name)

However, since I was pushing the temp file from inside the with, the file still wasn't closed, so the file I was pushing was truncated. This resulted in the same insecure string pickle error in the script that read the file on the remote machine.

Two potential fixes to this: Keep the file open and force a flush:

with tempfile.NamedTemporaryFile(mode='wb') as temp_file:
    pickle.dump(foo, temp_file)
    temp_file.flush()

    # Push file to another machine
    _send_file(temp_file.name)

Or make sure the file is closed before doing anything with it:

file_name = ''
with tempfile.NamedTemporaryFile(mode='wb', delete=False) as temp_file:
    file_name = temp_file.name
    pickle.dump(foo, temp_file)

# Push file to another machine
_send_file(file_name)