device syntax

[Hollis Blanchard]

I was thinking about how GRUB specifies device paths using 
"(device,partition)/path" syntax. That's a problem because Open 
Firmware device paths can contain commas. The legal character list is 
the alphanumerics plus ", . _ + -". My Mac's video card is named 
"ATY,Rage128y", and I'm pretty sure I've seen disks with commas in 
their names.

I think what we need is architecture-specific functions that can parse 
a device path into device, partition, and path parts. That would mean 
different syntaxes for the different ports, but I think this is the way 
to go. I see there is already a grub_file_get_device_name() function 
used in a few places; what about also providing 
grub_file_get_partition() and grub_file_get_path() functions?

-Hollis