#!/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=`{grep '^part 9fat ' /dev/$disk/ctl |awk '{print $3}'}
if(! ~ $#p9offset 1) {
	echo 'could not find plan 9 partition.'
	echo 'cannot happen'
	exit bad
}

if(test $p9offset -gt 4128695) {	# 65536 * 63 - 10
	echo 
	echo 'Your Plan 9 partition is more than 2GB into your disk,'
	echo 'and the master boot records used by Windows 9x/ME'
	echo 'cannot access it (and thus cannot boot it).'
	echo
	echo 'You can install the Plan 9 master boot record, which can load'
	echo 'partitions far into the disk.'
	echo 
	echo 'If you use the Windows NT/2000/XP master boot record'
	echo 'or a master boot record from a Unix clone (e.g., LILO or'
	echo 'FreeBSD bootmgr, it is probably safe to continue using'
	echo 'that boot record rather than install the Plan 9 boot record.'
	echo
	prompt 'Install the Plan 9 master boot record' y n 
	switch($rd) {
	case n
		;
	case y
		disk/mbr -m /386/mbr /dev/$disk/data
	}
}

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(~ $#p9part 0){
	echo 'You have no Plan 9 partitions (How could this happen?)' >[1=2]
	exit 'no plan 9 partition found'
}
p9part=$p9part(1)
{ echo 'A '^$p9part; echo w } | disk/fdisk /dev/$disk/data >[2]/dev/null >/dev/null
x=$status
if(~ $x '' '|'){
	echo
	echo 'The Plan 9 partition is now marked as active.'
	exit ''
}
exit $x