workaround for BIOS / CHS stuff

[Andrew Clausen]

Hi all,

Steffen Winterfeldt at suggested we use data contained in Microsoft file
systems to determine the BIOS / CHS geometry, if there are any.  I've
put this in CVS, which is available (as always) at:

        http://alioth.debian.org/projects/parted/

Please try it out!  It works for me :)

Here's a summary of the new semantics:

 * read in the main partition table (i.e. don't look inside extended
partitions yet)

 * check if the partition table is consistent with the BIOS geometry.

 * if it isn't, then first try looking in Microsoft file systems.
If that works, quietly adopt the Microsoft geometry.  If it doesn't
work (because the FS is very broken, or there are no MS file systems),
then the old technique of searching for a consistent geometry applies.
If a consistent geometry is found, the old warning comes up explaining
the situation.

Note: as always, Parted will write the CHS values it believes are
correct for every partition, rather than conservatively keep the
partitions the same unless they change.  I think this is a good strategy
if Parted is good at detecting geometry, but a bad strategy if it
gets it wrong badly.  Before the 2.6.x issues, this seemed to work well,
because it quietly fixed lots of problems :)  I hope this new version
will also.  Any arguments against?

Other comments?

Cheers,
Andrew