Where bitmap is a Python long, consider the innocent looking Pythonexpression:

bitmap = bitmap & ~(1L << bit)

This is the perfectly normal way of clearing a bit in a bitmap, soit looks like there's nothing peculiar going on here.

Except that Python longs are of indefinite (and theoretically infinite)length, and what makes this expression work in normal integers is thatthe two pieces have the same (finite) size. So Python is clearly notjust doing straight binary operations here

Most archive formats, such as tarballs, cpio archives, and zip archives,interleave the file names (and their directory structure) with the filecontents. The dump filesystem backup program such as Solaris ufsdump do not. The dump archive format starts with an index that has all of thefilenames and the directory structure; after this comes the actual filecontent, labeled by inode number.

This has an important consequence for detecting damaged archives. In aninterleaved format like a tarfile, getting a full file listing requiresreading the