Well, I just learned that installing FreeBSD 5.0 on the 2nd half of a disk 
that has NetBSD on the 1st half isn't very safe. (Possibly it happened 
because the disk was at wd2, not sure). Not only did the FreeBSD install 
fail to complete, it ended up trashing the NetBSD disklabel so that it said 
it was corrupt, and only shows partitions d, e, and f (and shows e starting 
at offset 63 and going to the end of the disk, which wasn't the case before).

Fortunately this was a test disk, so there was nothing important on it. 
Unfortunately, this means that I didn't take the time to mirror the disk 
anywhere before I tried the install, and it will take me several hours to 
rebuild all the pkgsrc stuff it had, and time to re-discover the right 
XF86Config files. I have a suspicion that the data is all still there, if I 
could just get the old disklabel back in place.

Is there any utility that will search through the disk and find the start 
of FFS partitions (and maybe even their sizes)? Failing that, is there a 
short primer somewhere on what the start of an FFS partition looks like so 
I can whack together a quick tool to do so? Or should I give up and start 
reinstalling/building/configuring?