The Zip archive format allows absolute pathnames (i.e. those starting with '/'). Most people don't use them, but it's generally possible to do so (possibly inadvertently).
My ArchiveViewer allows extraction of all the files in an archive (which may have a mixture of absolute and relative names) into a particular directory. The obvious way to handle this is also a potentially dangerous one: use the given directory as the root for the relative files, but extract the absolute ones to their desired path. i.e., if you have an archive with the files (trailing / denotes a directory):
/a/ /a/b c/d/ c/d/e
and extracted to /tmp, you would get:
/a/ /a/b /tmp/c/d/ /tmp/c/d/e
Under Unix and some Windows NT systems, file permissions may protect files you don't own from being clobbered.
The other obvious way to handle the problem is to make all files relative whether or not they started out that way in the archive, so we'd extract the above as:
/tmp/a/ /tmp/a/b /tmp/c/d/ /tmp/c/d/e
If you wanted to extract to the root, of course, that's up to you and your filesystem security.
I'm leaning toward the second strategy; does anyone have a preference on this that they'd like to share?