#!/bin/sh

# larch-rebuild   - rebuild the live system (by merging in the overlays)

# Author: Michael Towers (larch42 at googlemail dot com)
#
# This file is part of the larch project.
#
#    larch 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 of the License, or
#    (at your option) any later version.
#
#    larch 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 larch; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#
#----------------------------------------------------------------------------
# 2009.09.14

# This script doesn't produce a complete merged live system, it just
# rebuilds system.sqf and mods.sqf so that basically the whole system is
# in system.sqf, a tiny bit (/boot and /mnt) in mods.sqf. filter.sqf
# and overlay.tar.lzo are then not (initially) needed.

# $1 - the path to the folder where system.sqf and mods.sqf are to be placed

APP=$( basename $0 )
# test if the script is started by root user. If not, exit
if [ $UID -ne 0 ]; then
    echo "Only root can run ${APP}"; exit 1
fi

# Underlying system:        /.livesys/system
# 'filter' layer:           /.livesys/filter
# 'mods' layer:             /.livesys/mods
# Overlay:                  /.livesys/overlay2

domerge ()
{
    # Make a directory for a merged union
    merge_union=/.livesys/merge_union
    rm -rf ${merge_union}
    mkdir -p ${merge_union}

    # Unpack the overlay from the boot medium
    overlay=/.livesys/medium/larch/overlay.tar.lzo
    rm -rf /.livesys/{overlay2,overlay2x}
    if [ -f ${overlay} ]; then
        mkdir /.livesys/overlay2x
        /tfs/system/usr/bin/lzop -d < ${overlay} | \
                /tfs/system/bin/tar -C /.livesys/overlay2x -xf -
        mv /.livesys/overlay2x/overlay /.livesys/overlay2
        rm -r /.livesys/overlay2x
    else
        mkdir /.livesys/overlay2
    fi

    echo "Mounting merge union"
    layers="/.livesys/overlay2=${ovlmnt}:/.livesys/mods=${sqfmnt}"
    if [ -d /.livesys/filter ]; then
        layers="${layers}:/.livesys/filter=${sqfomnt}"
    fi
    layers="${layers}:/.livesys/system=${sqfmnt}"
    mount -n -t ${utype} -o ro,${bropt}${layers} ${utype} ${merge_union}
    if [ $? -ne 0 ]; then
        echo "** Couldn't mount merge union."
        return 1
    fi

    newsys ${merge_union}
    res=$?

    # Discard merge union
    umount -n ${merge_union}
    rm -r ${merge_union}

    # Discard overlay2
    rm -rf /.livesys/overlay2

    return ${res}
}


newsys ()
{
    union=$1
    echo "Building new 'system.sqf'"

    # root directories which are ignored in system.sqf
    ignoredirs="boot dev mnt media proc sys tmp .livesys .larch"
    # /var stuff
    ignoredirs="${ignoredirs} var/log var/tmp var/lock var/cache/pacman/pkg"
    mksquashfs ${union} "${sqfpath}/system.sqf" -e ${ignoredirs}
    if [ $? -ne 0 ]; then
        echo "ERROR: Couldn't create ${sqfpath}/system.sqf"
        return 1
    fi
    chmod oga-x "${sqfpath}/system.sqf"

    echo "Building new 'mods.sqf'"
    # mods.sqf just has the boot and mnt directories
    ignoredirs=""
    for f in $( ls -A ${union} ); do
        if [ "${f}" != "boot" ] && [ "${f}" != "mnt" ]; then
            ignoredirs="${ignoredirs} ${f}"
        fi
    done
    mksquashfs ${union} "${sqfpath}/mods.sqf" -e ${ignoredirs}
    if [ $? -ne 0 ]; then
        echo "ERROR: Couldn't create ${sqfpath}/mods.sqf"
        return 1
    fi
    chmod oga-x "${sqfpath}/mods.sqf"

    return 0
}


rebuild()
{
    utype="$( cat /.livesys/utype )"
    if [ "${utype}" = "aufs" ]; then
        sqfmnt="rr"
        sqfomnt="rr+wh"
        ovlmnt="ro+wh"
        ovlwmnt="rw"
        bropt="br:"
        opq=".wh..wh..opq"

    elif [ "${utype}" = "unionfs" ]; then

    # It might well be that unionfs requires a writeable top layer, so the
    # present code would need modifying ...

        sqfmnt="ro"
        sqfomnt="ro"
        ovlmnt="ro"
        ovlwmnt="rw"
        bropt="dirs="
        opq=".wh.__dir_opaque"

    else
        echo "ERROR: Couldn't determine type of unification file-system"
        return 1
    fi

    if domerge; then
        echo "Merge successful"
    else
        rm -f "${sqfpath}/system.sqf"
        rm -f "${sqfpath}/mods.sqf"
        return 1
    fi
}


# The folder (path) where the archives will be saved
sqfpath="$1"

if [ -d "${sqfpath}" ]; then
    echo "Rebuild squashfs archives to ${sqfpath}"
    rebuild
else
    echo "ERROR: invalid directory (${sqfpath})"
    exit 1
fi