#!/bin/rc

first=`{ls -p '#S' | sed 1q}
if(! ~ $first $disk) {
	echo 'warning: The plan 9 partition is not on the boot disk,'
	echo 'so making it the active partition will have no effect.'
}

p9offset=`{disk/fdisk -p /dev/$disk/data |grep '^part plan9 ' | awk '{print $4}'}
if(! ~ $#p9offset 1) {
	echo 'could not find plan 9 partition.'
	echo 'cannot happen'
	exit bad
}

if(test $p9offset -gt 4128705) {	# 65536 * 63
	echo 
	echo 'Your Plan 9 partition is more than 2GB into your disk,'
	echo 'and the master boot records used by most operating systems'
	echo 'cannot access it (and thus cannot boot it).'
	echo
	echo 'Would you like to install a master boot record'
	echo 'that will be able to access partitions more than 2GB into the disk?'
	echo
	prompt 'Install a new mbr' y n 
	switch($rd) {
	case n
		echo
		echo 'Not setting Plan 9 partition active, then.'
		echo
		exit bad
	case y
		disk/mbr -m /386/mbr /dev/$disk/data
	}
}

# silently install pbslba if the partition is way into the disk.
# it''s our only hope.
if(test $p9offset -gt 16434495)	# 1024*63*255 (8.5GB)
	disk/format -b /386/pbslba /dev/$disk/9fat

log Setting Plan 9 partition active.
p9part=`{disk/fdisk /dev/$disk/data >[2]/dev/null </dev/null | 
		grep PLAN9 | sed 1q | sed 's/ *(p.) .*/\1/'}
if(~ $#p9part 1) {
	{ echo 'A '^$p9part; echo w } | disk/fdisk /dev/$disk/data >[2]/dev/null >/dev/null
}

echo
echo 'The Plan 9 partition is now marked as active.'