#!/bin/rc

arg0=$0
DISPLAY=:0
HOME=/tmp
PATH=/bin:/usr/bin:/sbin:/usr/sbin:/usr/X11R6/bin:/usr/games

x=''
e=/bin/linuxemu
r=/sys/lib/linux

fn eprint {
	echo $arg0: $* >[1=2]
}

fn usage {
	echo usage: $arg0 [-h] [-d...] [-u uid] [-g gid] [-startx] [-display :n] [-e emubin] [-r linuxroot] command [args ...] >[1=2]
	exit usage
}

# extract options
o=()
while(~ $1 -*){
	switch($1){
	case -h
		usage
	case -r
		shift
		r=$1
	case -e
		shift
		e=$1
	case -startx
		x=1
	case -display
		shift
		DISPLAY=$1
	case -[ug]
		o=($o $1 $2)
		shift
	case -*
		o=($o $1)
	}
	shift
}

switch($#*){
case 0
	usage
}

if(! ~ $x ''){
	# find free local display
	d=(`{{seq 0 32; {echo /srv/UD.X* | sed 's!/srv/UD\.X!!g; s!\ !\
	!g; s!\*!!g;'}} | sort | uniq -c | awk '/^\ *1\ /{print $2}'})
	d=$d(1)
	X11/equis -ac :$d &
	k=/proc/$apid/notepg
	$arg0 -e $e -r $r -display :$d $o $*
	{echo kill >$k} >/dev/null >[2=1]
	exit
}

# rewrite the path so it would accessible after binding $r to /
fn ninepath {
	if(~ $1 /* && test -e $1 && ! test -e $r/$1){
		echo /9$1
	}
	if not {
		echo $1
	}
}

w=`{pwd}
r=`{cleanname -d $w $r}
if(! test -d $r){
	eprint bad rootpath: $r
	exit rootpath
}
e=`{cleanname -d $w $e}
if(! test -x $e){
	eprint bad emubin: $e
	exit emubin
}
e=`{ninepath $e}
p=`{ninepath $w}
a=($e $o)
while(! ~ $#* 0){
	x=`{ninepath $1}
	a=($a $"x)
	shift
}

# bind the required plan9 stuff
rfork n
mntgen $r
bind -a '#P' /dev
for(d in /9 /dev /proc /net /env /srv /n /mnt /tmp){
	t=$r^$d
	switch($d){
	case /tmp /env /srv
		bind -c $d $t
	case /9
		bind / $t
	case *
		bind $d $t
	}
}

# change root and run the emulator
builtin cd /
bind $r /
builtin cd $p
exec $a