Neither alternative you present is really 'good.' I can't come up 
with a 'good' one either, but I think I prefer a variant on the 
second scheme: Rather than effectively strip off any leading slash, 
prepend a name that's descriptive but not likely to conflict, 
something like 'zip_absolute'. For your example, this would yield the 
extracted files

/tmp/zip_absolute/a/
/tmp/zip_absolute/a/b
/tmp/c/d/
/tmp/c/d/e

My reasoning is that this makes it easier to put those files where 
you want them. Scattering them throughout the file system, as could 
happen if the absolute paths were honored, makes that difficult. 
Mixing the absolute files in with the relative ones in the same 
directory structure also could make a jumble that's hard to unravel 
if that's not where you wanted them. With a 'zip_absolute' directory 
it's not too hard to move all the files within that hierarchy to 
achieve the results of either of the other two schemes, or to put 
them somewhere else entirely.

-Martin


At 6:05 PM -0700 9/27/01, Ned Konz wrote:
>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?
>
>--
>Ned Konz
>currently: Stanwood, WA
>email:     ned at bike-nomad.com
>homepage:  http://bike-nomad.com