#!/bin/bash

# $Id:$
#
# This provides a stripped down 'failsafe' mode for situations
# where X is failing to start up.

# Author: Bryce W. Harrington <bryce@canonical.com>

# Copyright (C) 2010 Canonical, Ltd.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


xorg_conf_failsafe=${BPX_XORG_CONF_FAILSAFE:-"/etc/X11/xorg.conf.failsafe"}
xorg_conf=${BPX_XORG_CONF:-"/etc/X11/xorg.conf"}
fallback_driver=${BPX_FALLBACK_DRIVER:-"vesa"}
client=${BPX_CLIENT:-"/usr/share/xdiagnose/failsafeXinit"}
clientargs=${BPX_CLIENTARGS:-$xorg_conf_failsafe}
main_driver=${BPX_DRIVER:-"vesa"}
checkduration=${BPX_CHECK_DURATION:-30}
failsafe_log=${BPX_LOG:-"/var/log/gdm/failsafe.log"}

server=${BPX_SERVER:-/usr/bin/X}
serverargs=${BPX_SERVERARGS:-"$*"}
serverargs="${serverargs} -br -once -config $xorg_conf_failsafe -logfile /var/log/Xorg.failsafe.log"
   # -br:      Black background
   # -once:    Terminate server after one session
   # -config:  Specify location of xorg.conf file to use
   #           Note: Only root can specify absolute paths
   # -logfile: Don't overwrite Xorg.0.log

warn() {
    echo "Warning:  $1" 1>&2
}

is_installed() {
    prog=$1
    need=$2
    /usr/bin/which $prog > /dev/null 2>&1
    err=$?
    if [ ! $err = 0 ]; then
	warn "Could not $need because $prog is not installed ($err)"
	return $err
    fi
    return 0
}

# Tests if the given pciids are in numerical order from least to greatest
# (e.g., $a <= $b <= $c <= ...)
pciids_in_order() {
    lastid=0
    for pciid in $* ; do
        # Strip embedded : and convert hex to dec
        id=$((0x${pciid/:/}))
        if [ $id -lt $lastid ]; then
            return 1
        fi
        lastid=$id
    done
    return 0
}

get_driver() {
    machine=$(uname -m)
    if grep -q -E '(nouveau|drm)fb' /proc/fb; then
        echo "fbdev"
    elif [ $machine = "ppc" ]; then
        echo "fbdev"
    elif [ $machine = "powerpc" ]; then
        echo "fbdev"
    elif [ $machine = "ppc64" ]; then
        echo "fbdev"
    else
        echo $fallback_driver
    fi
    return 0
}

# Check if we've already attempted a failsafe session without success
if [ -e "$failsafe_log" ]; then
    cur_time=$(date +"%s")
    last_run=$(tail -n 1 $failsafe_log | cut -d' ' -f1)
    time_diff=$(expr $cur_time - $last_run)
    if [ $time_diff -lt $checkduration ]; then
        warn "Failsafe mode was already attempted within $checkduration seconds."
        warn "Falling back to gdm to report the issue."
        exit 1
    fi
fi

driver=$(get_driver)

# If no failsafe xorg.conf exists, generate a stock one
if [ ! -e $xorg_conf_failsafe ]; then
    cat > $xorg_conf_failsafe <<EOF
Section "Device"
	Identifier	"Configured Video Device"
	Driver		"vesa"
EndSection

Section "Monitor"
	Identifier	"Configured Monitor"
EndSection

Section "Screen"
	Identifier	"Default Screen"
	Monitor		"Configured Monitor"
	Device		"Configured Video Device"
EndSection
EOF
fi

md5xorg=$(md5sum $xorg_conf)
date +"%s $md5xorg" >> $failsafe_log
if [ $? -ne 0 ]; then
    warn "Cannot write to $failsafe_log"
fi

# TODO:  Start up the failsafe X session using their regular user account

if pidof /usr/sbin/gdm ; then
    clientargs="${clientargs} with-gdm"
fi

# Stop gdm if it's running, otherwise it will attempt to manage the display
# out from under us
if pidof /usr/sbin/gdm ; then
    exec kill -STOP $PPID
fi

echo "xinit $client $clientargs -- $server $serverargs"
xinit $client $clientargs -- $server $serverargs

# This seems to cause gdm to attempt to start a new x session
#exec kill -USR1 `cat /var/run/gdm.pid`
