Unzip nested zip files in python

Question

I am looking for a way to unzip nested zip files in python. For example, consider the following structure (hypothetical names for ease):

• Folder
  • Zipfi

Answer 1

Here's a function I came up with.

def extract_nested_zipfile(path, parent_zip=None):
    """Returns a ZipFile specified by path, even if the path contains
    intermediary ZipFiles.  For example, /root/gparent.zip/parent.zip/child.zip
    will return a ZipFile that represents child.zip
    """

    def extract_inner_zipfile(parent_zip, child_zip_path):
        """Returns a ZipFile specified by child_zip_path that exists inside
        parent_zip.
        """
        memory_zip = StringIO()
        memory_zip.write(parent_zip.open(child_zip_path).read())
        return zipfile.ZipFile(memory_zip)

    if ('.zip' + os.sep) in path:
        (parent_zip_path, child_zip_path) = os.path.relpath(path).split(
            '.zip' + os.sep, 1)
        parent_zip_path += '.zip'

        if not parent_zip:
            # This is the top-level, so read from disk
            parent_zip = zipfile.ZipFile(parent_zip_path)
        else:
            # We're already in a zip, so pull it out and recurse
            parent_zip = extract_inner_zipfile(parent_zip, parent_zip_path)

        return extract_nested_zipfile(child_zip_path, parent_zip)
    else:
        if parent_zip:
            return extract_inner_zipfile(parent_zip, path)
        else:
            # If there is no nesting, it's easy!
            return zipfile.ZipFile(path)

Here's how I tested it:

echo hello world > hi.txt
zip wrap1.zip hi.txt
zip wrap2.zip wrap1.zip
zip wrap3.zip wrap2.zip

print extract_nested_zipfile('/Users/mattfaus/dev/dev-git/wrap1.zip').open('hi.txt').read()
print extract_nested_zipfile('/Users/mattfaus/dev/dev-git/wrap2.zip/wrap1.zip').open('hi.txt').read()
print extract_nested_zipfile('/Users/mattfaus/dev/dev-git/wrap3.zip/wrap2.zip/wrap1.zip').open('hi.txt').read()