import hashlib


def hash_file(filename):
    """
    Generate a hash for the contents of a file
    """
    hasher = hashlib.sha1()
    with open(filename, 'rb') as f:
        buf = f.read(65536)
        while len(buf) > 0:
            hasher.update(buf)
            buf = f.read(65536)

    return hasher.hexdigest()