path: root/scripts/casper

#!/bin/sh

# set -e

mountpoint=/live_media
root_persistence="casper-rw"
home_persistence="home-rw"

mkdir -p $mountpoint

overlay_method=unionfs
if [ "${DPKG_ARCH}" = "ia64" ] || [ "${DPKG_ARCH}" = "hppa" ] || [ "${DPKG_ARCH}" = "sparc" ]; then
    overlay_method=devmapper
fi

USERNAME=debian
USERFULLNAME="Debian Live user"
HOST=debian

[ -f /etc/casper.conf ] && . /etc/casper.conf

export USERNAME USERFULLNAME HOST

casper_path() { # Fixme: uglyness
    path=$1
    if [ -e "$path/casper/filesystem.cloop" ]; then
        echo "$path/casper/filesystem.cloop"
        return 0
    elif [ -e "$path/casper/filesystem.squashfs" ]; then
        echo "$path/casper/filesystem.squashfs"
        return 0
    elif [ -e "$path/casper/filesystem.ext2" ]; then
        echo "$path/casper/filesystem.ext2"
        return 0
    elif [ -e "$path/casper/filesystem.xfs" ]; then
        echo "$path/casper/filesystem.xfs"
        return 0
    fi
    return 1
}

subdevices() {
    sysblock=$1
    r=""
    for dev in "${sysblock}" "${sysblock}"/*; do
        if [ -e "${dev}/dev" ]; then
            r="${r} ${dev}"
        fi
    done
    echo ${r}
}

get_backing_device() {
	case "$1" in
            *.cloop)
                echo $(setup_loop "$1" "cloop" "/sys/block/cloop*")
			;;
            *.squashfs|*.ext2|*.xfs)
                echo $(setup_loop "$1" "loop" "/sys/block/loop*")
                ;;
            *)
                panic "Unrecognized casper filesystem: $1"
                ;;
	esac
}

setup_cow() {
	case "$1" in
            unionfs)
                setup_unionfs "$2" "$rootmnt"
                ;;
            devmapper)
                setup_devmapper "$2" "$rootmnt"
	esac
}

sys2dev() {
    sysdev=${1#/sys}
    echo "/dev/$(udevinfo -q name -p ${sysdev} 2>/dev/null|| echo ${sysdev##*/})"
}

setup_loop() {
    local fspath=$1
    local module=$2
    local pattern=$3

    modprobe -qb "$module"
    if [ -x /sbin/udevplug ]; then
        udevplug -W
    else
        udevtrigger
    fi
 
    for loopdev in $pattern; do
        if [ "$(cat $loopdev/size)" -eq 0 ]; then
            dev=$(sys2dev "${loopdev}")
            losetup "$dev" "$fspath"
            echo "$dev"
            return 0
        fi
    done
    panic "No loop devices available"
}

get_fstype() {
    local FSTYPE
    local FSSIZE
    eval $(fstype < $1)
    if [ "$FSTYPE" != "unknown" ]; then
        echo $FSTYPE
        return 0
    fi
    /lib/udev/vol_id -t $1 2>/dev/null
}

setup_devmapper() {
    backdev="$1"
    rootmnt="$2"

    modprobe -qb dm-mod
    COW_DEVICE=/dev/ram1
    COW_NAME="casper-cow"

    BACKING_FILE_SIZE=$(blockdev --getsize "$backdev")
    MAX_COW_SIZE=$(blockdev --getsize "$COW_DEVICE")
    CHUNK_SIZE=8 # sectors

    if [ -z "$COW_SIZE" -o "$COW_SIZE" -gt "$MAX_COW_SIZE" ]; then
        COW_SIZE=$MAX_COW_SIZE
    fi

    echo "0 $COW_SIZE linear $COW_DEVICE 0" | dmsetup create $COW_NAME

    echo "0 $BACKING_FILE_SIZE snapshot $backdev /dev/mapper/$COW_NAME p $CHUNK_SIZE" | \
        dmsetup create casper-snapshot
    if [ "$(get_fstype $backdev)" = "unknown" ]; then
        panic "Unknown file system type on $backdev"
    fi
    mount -t $(get_fstype "$backdev") /dev/mapper/casper-snapshot $rootmnt || panic "Can not mount /dev/mapper/casper/snapshot on $rootmnt"

    mkdir -p "$rootmnt/rofs"
    echo "0 $BACKING_FILE_SIZE linear $backdev 0" | dmsetup create casper-backing
    mount -t $(get_fstype "$backdev") /dev/mapper/casper-backing "$rootmnt/rofs"
}

where_is_mounted() {
    device=$1
    if grep -q "^$device " /proc/mounts; then
        grep "^$device " /proc/mounts | read d mountpoint rest
        echo $mountpoint
        return 0
    fi
    return 1
}

copy_to_ram() {
	copyto="${mountpoint}_swap"

	size=$(du -ks ${mountpoint} | cut -f1)
	size=$(expr ${size} + ${size}/20 ) # Fixme: 5% more to be sure
	needed_space=$(expr ${size} * 1024)
	freespace=$( expr $(awk '/MemFree/{print $2}' /proc/meminfo) + $( cat /proc/meminfo | grep Cached | head -n 1 | awk '/Cached/{print $2}' - ))
	
	if [ ! ${freespace} -lt ${needed_space}  ] ; then
		[ "$quiet" != "y" ] && log_begin_msg "Not enough free memory to copy to ram"
		[ "$quiet" != "y" ] && log_end_msg
		return
	else
		[ "$quiet" != "y" ] && log_begin_msg "Copying live media to ram..."
		mkdir "${copyto}"
		mount -t tmpfs -o size=${size}k /dev/shm ${copyto}
		cp -a ${mountpoint}/* ${copyto}
		umount ${mountpoint}
		mount -r -o move ${copyto} ${mountpoint}
		rmdir ${copyto}
		[ "$quiet" != "y" ] && log_end_msg
	fi
}

find_cow_device() {
	pers_label="${1}"
	cow_backing="/${pers_label}-backing"
	for sysblock in $(echo /sys/block/* | tr ' ' '\n' | grep -v loop); do
		for dev in $(subdevices "${sysblock}"); do
			devname=$(sys2dev "${dev}")
			if [ "$(/lib/udev/vol_id -l $devname 2>/dev/null)" = "${pers_label}" ]; then
				echo "$devname"
				return
			elif [ "$(get_fstype ${devname})" = "vfat" ]; then
				mkdir -p "${cow_backing}"
				if where_is_mounted ${devname} > /dev/null; then
					mount -o remount,rw ${devname} $(where_is_mounted ${devname}) || panic "Remounting failed"
					mount -o bind $(where_is_mounted ${devname}) ${cow_backing} || panic "Cannot bind-mount"
				else
					mount -t $(get_fstype "${devname}") -o rw "${devname}" ${cow_backing} || panic "Cannot mount $devname on /cow-backing"
				fi

				if [ -e "${cow_backing}/${pers_label}" ]; then
					echo $(setup_loop "${cow_backing}/${pers_label}" "loop" "/sys/block/loop*")
					return 0
				else
					umount ${cow_backing}
				fi
			fi
		done
	done
}

do_netmount() {
	rofsmnt="$1"
	# adapted from NFS filesystem mounting

	modprobe -q cifs
	# For DHCP
	modprobe -q af_packet

	ipconfig ${DEVICE} /tmp/net-${DEVICE}.conf
	if [ "x${NFSROOT}" = "xauto" ]; then
		NFSROOT=${ROOTSERVER}:${ROOTPATH}
	fi

	NFSOPTS="-ouser=root,password="

	[ "$quiet" != "y" ] && log_begin_msg "Mounting using mount.cifs with ${NFSROOT} ${rofsmnt} ${NFSOPTS}"
	mount.cifs "${NFSROOT}" "${rofsmnt}" "${NFSOPTS}" 
	[ "$quiet" != "y" ] && log_end_msg
}

setup_unionfs() {
	backdev="$1"
	rootmnt="$2"
	modprobe -qb unionfs
	mkdir -p /cow
	cowdevice="tmpfs"
	cow_fstype="tmpfs"
	# Looking for "${root_persistence}" device or file
	if grep -q persistent /proc/cmdline; then
		cowprobe=$(find_cow_device "${root_persistence}")
		if [ -b "${cowprobe}" ]; then
			cowdevice=${cowprobe}
			cow_fstype=$(get_fstype "${cowprobe}")
		else
			[ "$quiet" != "y" ] &&	log_begin_msg "Unable to find the persistent medium"
		fi
	fi

	mount ${cowdevice} -t ${cow_fstype} -o rw /cow || panic "Can not mount $cowdevice on /cow"

	mkdir -p /rofs
	if grep -q netboot /proc/cmdline; then
		do_netmount /rofs || panic "Can not mount netroot on /rofs"
	else
		if [ "$(get_fstype $backdev)" = "unknown" ]; then
			panic "Unknown file system type on $backdev"
		fi
		mount -t $(get_fstype "$backdev") -o ro "$backdev" /rofs || panic "Can not mount $backdev on /rofs"
	fi
	
	mount -t unionfs -o dirs=/cow=rw:/rofs=ro unionfs "$rootmnt"
	if grep -q show-cow /proc/cmdline; then
		mkdir -p "$rootmnt/cow"
		mount -o bind /cow "$rootmnt/cow"
	fi
	mkdir -p "$rootmnt/rofs"
	mount -o bind /rofs "$rootmnt/rofs"

	# Adding home persitence
	if grep -q homepersistence /proc/cmdline; then
		homecow=$(find_cow_device "${home_persistence}" )
		if [ -b "${homecow}" ]; then
			mount ${homecow} -t $(get_fstype "${homecow}") -o rw "${rootmnt}/home"
		else 
			[ "$quiet" != "y" ] &&  log_begin_msg "Unable to find the persistent home medium"
		fi
	fi
}

is_usb_device() {
    sysfs_path="${1#/sys}"
    if /lib/udev/path_id "${sysfs_path}" | grep -q "ID_PATH=usb"; then
        return 0
    fi
    return 1
}

find_live() {
	mounted=
        for sysblock in $(echo /sys/block/* | tr ' ' '\n' | grep -v loop | grep -v ram); do
            devname=$(sys2dev "${sysblock}")
            fstype=$(get_fstype "${devname}")
            if /lib/udev/cdrom_id ${devname} > /dev/null; then
                mount -t ${fstype} -o ro "$devname" $mountpoint || continue
                if casper_path $mountpoint; then
                    echo $(casper_path $mountpoint)
                    return
                else
                    umount $mountpoint
                fi
            elif is_usb_device "$sysblock"; then
                for dev in $(subdevices "${sysblock}"); do
                    devname=$(sys2dev "${dev}")
                    fstype=$(get_fstype "${devname}")
                    case ${fstype} in
                        vfat|iso9660|udf)
                            mount -t ${fstype} -o ro "${devname}" $mountpoint || continue
                            if casper_path $mountpoint; then
                                echo $(casper_path $mountpoint)
                                return
                            else
                                umount $mountpoint
                            fi
                            ;;
                    esac
                done
	    elif [ "${fstype}" = "squashfs" ]; then

                # This is an ugly hack situation, the block device has
                # a squashfs image directly on it.  It's hopefully
                # casper, so take it and run with it.

                ln -s "${devname}" "${devname}.${fstype}"
                echo "${devname}.${fstype}"
                return
            fi
        done
}

set_usplash_timeout() {
    if [ -x /sbin/usplash_write ]; then
        /sbin/usplash_write "TIMEOUT 120"
    fi
}

mountroot() {
    exec 6>&1
    exec 7>&2
    exec > casper.log
    exec 2>&1

    set_usplash_timeout
    [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/casper-premount"
    run_scripts /scripts/casper-premount
    [ "$quiet" != "y" ] && log_end_msg

    # Needed here too because some things (*cough* udev *cough*)
    # changes the timeout

    set_usplash_timeout

    for i in 0 1 2 3 4 5 6 7 8 9 a b c d e f 10 11 12 13; do
        live_image=$(find_live)
        if [ "${live_image}" ]; then
            break
        fi
        sleep 1
    done
    if [ "$?" -gt 0 ]; then
        panic "Unable to find a medium containing a live file system"
    fi
    
	if grep -q toram /proc/cmdline; then
		copy_to_ram
	fi

    setup_cow "$overlay_method" "$(get_backing_device $live_image)" "$rootmnt"

	# show it on new rootfs
	mkdir ${rootmnt}/${mountpoint}
	mount -o bind ${mountpoint} ${rootmnt}/${mountpoint}

    log_end_msg

    maybe_break casper-bottom
    [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/casper-bottom"

    PATH=/root/usr/bin:/root/usr/sbin:/root/bin:/root/sbin:$PATH run_scripts /scripts/casper-bottom
    [ "$quiet" != "y" ] && log_end_msg

    exec 1>&6 6>&-
    exec 2>&7 7>&-
    cp casper.log "${rootmnt}/var/log/"
}