#!/bin/sh

# gox: script to start X with different resolutions and bpp.

############################################################################
# Paths to various config files:
#
XF86CONFIG=/etc/X11/XF86Config
FVWMCONFIG=/usr/X11R6/lib/X11/fvwm2/system.fvwmrc
TWMCONFIG=/etc/X11/twm/system.twmrc

# default command (e.g. wm) to run:
#
#cmd="exec fvwm -f $FVWMCONFIG"
cmd="exec twm -f $TWMCONFIG"

# default bpp and x-resolution:
bpp=16
res=800

############################################################################

Usage="
gox: start a simple X session (e.g. twm + xterm) with variable color
     depth (bpp) and screen resolution. Useful for running games that
     need lower resolution and/or number of colors.

Usage: gox [-c <cmd>] [-d <display>] <width> <bpp>

Defaults: width: $res
          bpp:   $bpp
          cmd:   $cmd
Notes:
	The root password will be required (to run: xinit -- -xf86config <file>
	via su(1))

	A free DISPLAY is searched for from :0 to :9 unless -d is used.

	The <cmd> above in -c is usually the window manager command to run,
	but it could simply just be the game (if it can run with no wm).

	The template xf86config file: \"$XF86CONFIG\" must have
	a \"Screen\" section with all of the desired resolutions on a
	\"Modes\" line. All of those resolutions must, of course, have
	corresponding \"ModeLine\" lines in the config file that work.
	If there are uncommon resolutions, it will be best if the used
	\"Screen\" section is the last one in the file since the resolutions
	are extracted from it.

Additional options:
	-u <user>	run the X session as <user>
	-C <cmd>	run <cmd> in background before starting the wm (i.e.
			the -c cmd). E.g. start the game, but also have a
			window manager."


program=`basename $0`
# process cmd line options:
while [ "$1" != "" ]
do
    case $1 in 
	"-c")	cmd="$2"; shift
                ;;
	"-C")	append_cmd="$2"; shift
                ;;
	"-d")	display="$2"; shift
                ;;
	"-u")	USER="$2"; export USER; shift
                ;;
	"-h"*)	echo "$Usage"; exit 0
                ;;
	"-"*)	echo; echo "$program: $1 not an option"; echo "$Usage"; exit 1
		;;
	*)	break
                ;;
    esac
    shift
done

# process cmd line operands:
if [ "$1" != "" -a "$2" != "" ]; then
	res=$1
	bpp=$2
elif [ "$1" != "" ]; then
	res=$1
fi

# check bpp:
case $bpp in
	8|16|24|32)	echo "bpp=$bpp"
		;;
	*)	echo "bad bpp: $bpp (use: 8|16|24|32)"; exit 1
		;;
esac

# check res:
case $res in
	1280|1024|800|640|480|400|320) echo "res=$res"
		;;
	*)	echo "bad res: $res (use: 1280|1024|800|640|480|400|320)"; exit 1
		;;
esac

if [ "$display" != "" ]; then
	DISPLAY="$display"; export DISPLAY
else
	# try to find an open DISPLAY (in case another X server is running)
	for i in 0 1 2 3 4 5 6 7 8 9
	do
		if netstat -ant | grep LISTEN | grep ":600$i" > /dev/null; then
			echo "display in use: 600$i" 
		else
			DISPLAY=":$i"; export DISPLAY
			echo "set DISPLAY to: $DISPLAY"
			break
		fi
	done
fi

# create tmpdir and filenames:
tmpdir="/tmp/gox.$USER.$$"
if [ -d "$tmpdir" ]; then
	echo "tmpdir already exists: $tmpdir"
	exit 1
fi

mkdir -m 0755 $tmpdir || exit 1
chmod 755 $tmpdir || exit 1

xconfig="$tmpdir/xconfig"
xinitrc="$tmpdir/xinitrc"
xclient="$tmpdir/xclient"

# get the XY resolution for the "Virtual":
XY=`grep '^[ 	]*Modes[ 	]' $XF86CONFIG \
	| grep "${res}x" \
	| sed -e 's/Modes/ /g' -e 's/[ 	][ 	]*/ /g' -e 's/"//g' \
	| tr ' ' '\n' \
	| grep "^${res}x" \
	| sed -e 's/x/ /g' \
	| tail -1`

if [ "$XY" = "" ]; then
	# error case, try these as backup..
	case $res in
		1280)	XY="1280 1024"
			;;
		1024)	XY="1024 768"
			;;
		800)	XY="800 600"
			;;
		640)	XY="640 480"
			;;
		480)	XY="480 320"
			;;
		400)	XY="400 300"
			;;
		320)	XY="320 240"
			;;
		*)	XY="800 600"; echo "warning set XY to $XY"
			;;
	esac
fi

echo "XY: $XY"

# modify the template XF86Config file to desired settings:
cat $XF86CONFIG | sed -e "s/^[ 	]*Depth.*$/ Depth $bpp/g" \
		      -e "s/^[  ]*Virtual.*$/ Virtual $XY/" > $xconfig

# create the xintirc to use:
if echo "$cmd" | grep -i wm >/dev/null; then
	# if cmd has string "wm" pop up an xterm to work in.
	xterm_cmd="export TERM=xterm; sleep 1; xterm -geometry 80x25+1+1 &"
else
	xterm_cmd=""
fi

if [ "$append_cmd" != "" ]; then
	append_cmd="sleep 1; $append_cmd &"
	if [ "$xterm_cmd" != "" ]; then
		xterm_cmd=`echo "$xterm_cmd" | sed -e 's/xterm /xterm -iconic /'`
	fi
fi
cat > $xinitrc << END
#!/bin/sh

$xterm_cmd
$append_cmd

# start window manager or supplied cmd:
$cmd

END

# create the "client" cmd script for xinit arg:
cat > $xclient << END
#!/bin/sh

# the following xhosts could be needed in some situations to allow
# windows from processes owned by the ordinary user:
#
#xhost +localhost
#xhost +`hostname`

su $USER -c $xinitrc
END

# make them both executable:
chmod 755 $xinitrc $xclient

# run xinit as root:
su root -c "xinit $xclient -- $DISPLAY -xf86config $xconfig"

# when it finishes, remove our junk:
rm -rf $tmpdir

exit 0