#!/usr/bin/python
"""Tells you whether a file is a valid zipfile by reading its end."""

import sys

def is_zip_name(filename):
    "Returns true if filename names a zipfile."
    return is_zip(open(filename, 'rb'))

def is_zip(f):
    "Returns true if open seekable file object f is open on a zipfile."
    chunksize = 1024
    f.seek(0, 2)
    chunksize = min(f.tell(), chunksize)
    f.seek(-chunksize, 1)
    s = f.read(chunksize)
    i = 0
    while True:
        i = s.find("PK\5\6", i+1)
        if i == -1:
            return False
        comment_length = ord(s[i+20]) | ord(s[i+21]) << 8
        if comment_length == chunksize - i - 22:
            return True

if __name__ == '__main__':
    for filename in sys.argv[1:]:
        print filename, "zipfile" if is_zip_name(filename) else "no"