CODEWITHSUNDEEP
pythonpython-2.7python-3.x
Hesam Qodsi
Hesam Qodsi

Reputation: 1585

marshal.loads function does not load *.pyc contents to code object

I Try this in Python 3.3

f = open(r'somewhere\my_module.pyc','rb')
contents = f.read()
f.close()

code_obj = marshal.loads(contents[8:])

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: bad marshal data (unknown type code)

I get error , so i convert contents variable type to str

def bytes2str(byte_seq):
    str_seq = ''
    for b in byte_seq:
        str_seq += chr(b)
    return str_seq

contents = bytes2str(contents)
code_obj = marshal.loads(contents[8:])

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'str' does not support the buffer interface

When i try this in Python 2.7 i get a code object. How to deal with this problem without using compile built-in function?

Upvotes: 5

Views: 2507

Answers (1)

Blckknght
Blckknght

Reputation: 104762

It seems the header of a .pyc file has changed in recent versions of Python to be 12 bytes, rather than 8. If you do code_obj = marshal.loads(contents[12:]), you'll get the code object you are seeking.

I've tried in vain to find documentation of this change to the PYC file format, but so far I've not had any luck. It seems like it started with Python 3.3 (which included quite a lot of changes to the import machinery), but I'm not sure which bit required the extra 4 bytes.

Upvotes: 6

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