manjaro-tools/initcpio/hooks/miso_overlayfs

# kernel_cmdline <param> <default>
# Looks for a parameter on the kernel's boot-time command line.
#
# returns: 0 if param was found. Also prints its value if it was a K=V param.
#          1 if it was not. Also prints value passed as <default>
#

kernel_cmdline ()
{
    for param in $(/bin/cat /proc/cmdline); do
        case "${param}" in
            $1=*) echo "${param##*=}"; return 0 ;;
            $1) return 0 ;;
            *) continue ;;
        esac
    done
    [ -n "${2}" ] && echo "${2}"
    return 1
}

# 1$ : kernel argument to check
overlay_arg_available() {
	for arg in $(echo "$(kernel_cmdline overlay)" | /bin/sed 's/,/ /g')
	do
		[ "${arg}" == "$1" ] && return 0
	done

	return 1
}

# args: source, mountpoint
_mnt_bind() {
    local src="${1}"
    local mnt="${2}"
    msg "::: Binding ${src} to ${mnt}"
    mkdir -p "${mnt}"
    /bin/mount -o bind "${src}" "${mnt}"
}

# args: /path/to/image_file, mountpoint
_mnt_squashfs() {
    local img="${1}"
    local mnt="${2}"
    local img_fullname="${img##*/}";
    local img_name="${img_fullname%.*}"
    local tmp_mnt="/ro_branch/${img_name}"

    if [ "${copytoram}" = "y" ]; then
        msg -n ":: Copying squashfs image to RAM..."
        /bin/cp "${img}" "/copytoram/${img_fullname}"
        if [ $? -ne 0 ]; then
            echo ">> ERROR: while copy ${img} to /copytoram/${img_fullname}"
            launch_interactive_shell
        fi
        img="/copytoram/${img_fullname}"
        msg "done."
    fi

    mkdir -p "${tmp_mnt}"
    /bin/mount -r -t squashfs "${img}" "${tmp_mnt}"
    if [ $? -ne 0 ]; then
        echo ">> ERROR: while mounting ${img} to ${tmp_mnt}"
        launch_interactive_shell
    fi

    if [ "/${mnt#/*/}" = "/" ]; then
        overlayfs="${overlayfs}:${tmp_mnt}"
    else
        _mnt_bind "${tmp_mnt}" "${mnt}"
    fi
}

run_hook() {
    modprobe loop
    if [ "x${arch}" = "x" ]; then
        arch="$(uname -m)"
    fi

    if [ "x${rw_branch_size}" = "x" ]; then
        rw_branch_size="75%"
    fi

    if [ "x${copytoram_size}" = "x" ]; then
        copytoram_size="75%"
    fi

    if [ "x${misobasedir}" = "x" ]; then
        misobasedir="manjaro"
    fi

    if [ "x${isomounts}" != "x" ]; then
        isomounts="/bootmnt/${isomounts}"
    else
        isomounts="/bootmnt/${misobasedir}/isomounts"
    fi

    # set mount handler for miso
    mount_handler="miso_mount_handler"
}

testdevice() {
    fstype=$( blkid -s TYPE -o value ${MDEV} )
    mount -r -t ${fstype} -o noatime "${MDEV}" "/bootmnt" >/dev/null 2>/dev/null
    if [ $? -eq 0 ]; then
        if [ -f "/bootmnt/.miso" ]; then
            msg "::: INFO: miso system at ${MDEV}"
            found="yes"
        else
            /bin/umount "/bootmnt/" 2>/dev/null
            msg  "::: INFO: No miso system at ${MDEV}"
            MDEV=""
        fi
    else
        msg ">> ERROR: Couldn't mount ${MDEV}"
        MDEV=""
    fi
}

probedevice() {

# Loop device test every second up to some limit
    if [ "x${usbdelay}" != "x" ]; then
        waittime=${usbdelay}
    else
        waittime=35
    fi
    waitcount=0
    while [ ${waittime} -ne ${waitcount} ]; do
        # first we look for root, e.g. /dev/sda1 to see if .miso will be found
        if [ "x${root}" != "x" ]; then
            [ ${waitcount} -eq 0 ] && msg ":: Looking for ${root}"
            if [ -e ${root} ]; then
                MDEV=${root}
                testdevice
            fi
        fi

        # if still not found, we will look for misolabel
        if [ "x${misolabel}" != "x" ]; then
            [ ${waitcount} -eq 0 ] && msg ":: Looking for LABEL ${misolabel}"
            MDEV=$( blkid -L ${misolabel} )
            if [ "x${MDEV}" != "x" ]; then
                testdevice
            else
                msg "::: INFO: LABEL ${misolabel} is not valid!"
                misolabel=""
            fi
        fi

        # still nothing found, we will look for boot device
        [ ${waitcount} -eq 0 ] && msg ":: Looking for boot device"
        if [ "x${nocd}" = "x" ]; then
            # Look for CD
            cdroms=$( /bin/cat /proc/sys/dev/cdrom/info | { while read a b c; do
                    if [ "${a}" = "drive" -a "${b}" = "name:" ]; then
                        echo "${c}"
                        break
                    fi
                done
            } )
            for i in ${cdroms}; do
                MDEV=/dev/${i}
                testdevice
                if [ "x${MDEV}" != "x" ]; then
                    break
                fi
            done
        fi

        # Test partitions
        if [ "x${MDEV}" = "x" ]; then
            for d in /dev/sd[a-z][0-9]*; do
                MDEV=${d}
                testdevice
                if [ "x${MDEV}" != "x" ]; then
                    break
                fi
            done
        fi

        [ "x${MDEV}" != "x" ] && break

        /bin/sleep 1
        waitcount=$(( ${waitcount} + 1 ))
    done
}

miso_mount_handler() {
    local newroot="${1}"
    local found
    local overlayfs

    # Probe all devices
    probedevice

    if [ -z "${found}" ]; then
        echo ">> ERROR: unable to find boot device"
        echo "   Falling back to interactive prompt"
        echo "   You can try to fix the problem manually, log out when you are finished"
        launch_interactive_shell
    fi

    if [ "${copytoram}" = "y" ]; then
        msg -n ":: Mounting /copytoram (tmpfs) filesystem, size=${copytoram_size}..."
        mount -t tmpfs -o "size=${copytoram_size}",mode=0755 copytoram /copytoram
        msg "done."
    fi

    msg -n ":: Mounting rw_branch (tmpfs) filesystem, size=${rw_branch_size}..."
    mount -t tmpfs -o "size=${rw_branch_size}",mode=0755 rw_branch /rw_branch
    msg "done."

    msg ":: Mounting images"
    while read img imgarch mountpoint type kernelarg; do
        # check if this line is a comment (starts with #)
        [ "${img#"#"}" != "${img}" ] && continue

        [ "$imgarch" != "$arch" ] && continue

        [ ! -r "/bootmnt/${misobasedir}/${img}" ] && continue

        # check if the overlay should be loaded
        overlay_arg_available "$kernelarg"


        if [ $? == 1 ] && [ "$kernelarg" != "" ]; then
	        continue
        fi

        if [ "${type}" = "bind" ]; then
            _mnt_bind "/bootmnt/${misobasedir}/${img}" "${newroot}${mountpoint}"
        elif [ "${type}" = "squashfs" ]; then
            _mnt_squashfs "/bootmnt/${misobasedir}/${img}" "${newroot}${mountpoint}"
        fi
    done < "${isomounts}"

    msg "Mounting ${overlayfs:1}"
    mkdir -p "/rw_branch/upper"
    mkdir -p "/rw_branch/work"
    mount -t overlay overlay -olowerdir="${overlayfs:1}",upperdir="/rw_branch/upper",workdir="/rw_branch/work" "${newroot}/"

    if [ "${copytoram}" = "y" ]; then
        /bin/umount -d /bootmnt
    else
        _mnt_bind /bootmnt "${newroot}/bootmnt"
    fi
}

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