Uberblock location

[Felipe Monteiro de Carvalho]

Hello,

I am writing a program to read ZFS partitions, and although I already
read a lot of documentation, there is 1 problem which is blocking me:
How does the driver find the uberblock?

I know, I can just get any test volume, find the ZFS uberblock and in
my case it is positioned in 0x20C00 and there are lots and lots of
copies (older versions?) of it.

But there is no guarantee that it doesn't just happen to be in this
position in my image and in another version it would be elsewhere, so
I need the algorithm utilized to find it.

Any ideas?

thanks,
-- 
Felipe Monteiro de Carvalho