#! /bin/bash

# Copyright (C) 2008 Stephane Levant <sun@tuxfamily.org>

#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2, or (at your option)
#  any later version.

#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.

#  You should have received a copy of the GNU General Public License
#  along with this program; see the file COPYING.  If not, write to the
#  Free Software Foundation, Inc., 59 Temple Place - Suite 330,
#  Boston, MA 02111-1307, USA.

VERSION=0.1
prog=`basename $0`

### User options
# The screen size
SCREEN_SIZE=640x480
# Select the uid of the user to use
UID_TO_USE=1001
# Select the console to use (use another if already used)
CONSOLE=8
# Select the display number to use (use another if already used)
DISPLAY_NB=1
# Commande that lauch virtualbox
VIRTUALBOX=virtualbox

### Code
# Display an error message
error() {
    echo "$prog: $1" >&2
    exit 1
}
[ $UID = 0 ] || error "Only root can start this script"
# Search for the virtualbox command
which $VIRTUALBOX &> /dev/null || VIRTUALBOX=Virtualbox
which $VIRTUALBOX &> /dev/null || error "Cannot find virtualbox"
# Get the name of the user to use
USER_TO_USE=$(awk -F: '$3 == '$UID_TO_USE' {print $1}' /etc/passwd)
# Use root user if not found
if [ "$USER_TO_USE" = "" ]; then
    echo "Warning: user uid 1001 not found, using root"
    UID_TO_USE=0
    USER_TO_USE=root
fi

# find a free tty
function isFree() {
    [ "$(lsof /dev/tty$1 | egrep -v 'getty|COMMAND')" = "" ]
}
if ! isFree $CONSOLE; then
    # Tests the 12 ttys
    for ((i=1;i<=12;i++)); do
        if isFree $i; then
            CONSOLE=$i
            break
        fi
    done
fi

# find a free server number
if [ -e /tmp/.X11-unix/X$DISPLAY_NB ]; then
    for ((i=1;i<=12;i++)); do
        if [ ! -e /tmp/.X11-unix/X$i ]; then
            DISPLAY_NB=$i
            break
        fi
    done
fi

# Display user message
echo "Start X on :$DISPLAY_NB, size=$SCREEN_SIZE, with user\
 uid $UID_TO_USE ($USER_TO_USE) on tty$CONSOLE"

# File to modify and trap
XWRAPPER=/etc/X11/Xwrapper.config
XWRAPPER_SVG=/etc/X11/Xwrapper.config.bak-brood
X11_CONF=/etc/X11/xorg.conf
X11_CONF_SVG=/etc/X11/xorg.conf.bak-brood
HOME_USER=$(awk -F: '$3 == '$UID_TO_USE' {print $6}' /etc/passwd)
XSESSION=$HOME_USER/.xsession
XSESSION_SVG=$HOME_USER/.xsession.bak-brood
TEMP_FILE=$(mktemp)
rm $TEMP_FILE

function exitProperly()
{
    [ -f "$X11_CONF_SVG" ] && mv "$X11_CONF_SVG" "$X11_CONF"
    [ -f "$XSESSION_SVG" ] && mv "$XSESSION_SVG" "$XSESSION"
    [ -f "$XWRAPPER_SVG" ] && mv "$XWRAPPER_SVG" "$XWRAPPER"
    exit 0
}

trap exitProperly 2 3 24

# Allow users to start X and renice Xserver
[ -f $XWRAPPER_SVG ] || mv $XWRAPPER $XWRAPPER_SVG
cat << EOF > $XWRAPPER
# Xwrapper.config (Debian X Window System server wrapper configuration file)
#
# This file was generated by the post-installation script of the x11-common
# package using values from the debconf database.
#
# See the Xwrapper.config(5) manual page for more information.
#
# This file is automatically updated on upgrades of the x11-common package
# *only* if it has not been modified since the last upgrade of that package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command as root:
#   dpkg-reconfigure x11-common
allowed_users=anybody
nice_value=-10
EOF

# Create a new config file xorg.conf
[ -f $X11_CONF_SVG ] || mv $X11_CONF $X11_CONF_SVG
awk ' {
if ($1=="Modes")
     print "\tModes\t\"'$SCREEN_SIZE'\""
else
     print
}' $X11_CONF_SVG > $X11_CONF

# Create a user .xsession file
[ -f $XSESSION_SVG ] || mv $XSESSION $XSESSION_SVG
#echo "touch $TEMP_FILE; exec $VIRTUALBOX" > $XSESSION
echo "touch $TEMP_FILE; exec $VIRTUALBOX" > $XSESSION
chown $USER_TO_USE $XSESSION

su -lc "startx -- :$DISPLAY_NB vt$CONSOLE -nolisten tcp \
        || touch $TEMP_FILE" $USER_TO_USE &

while :; do
    sleep 1
    echo "Waiting for X server to start..."
    [ -f $TEMP_FILE ] && exitProperly
done