#!/bin/bash
## If the container being cloned has one or more lxc.hook.clone
## specified, then the specified hooks will be called for the new
## container.  The arguments passed to the clone hook are:
##  1. the container name
##  2. a section ('lxc')
##  3. hook type ('clone')
##  4. .. additional arguments to lxc-clone
## Environment variables:
##  LXC_ROOTFS_MOUNT: path to the root filesystem
##  LXC_CONFIG_FILE:  path to config file
##  LXC_SRC_NAME:     old container name
##  LXC_ROOTFS_PATH:  path or device on which the root fs is located

set -f
VERBOSITY="0"

error() { echo "$@" 1>&2; }
debug() { [ "$VERBOSITY" -ge "$1" ] || return; shift; error "$@"; }
fail() { [ $# -eq 0 ] || error "$@"; exit 1; }

prep_usage() {
cat <<EOF
Usage: ${0##*/} [options] root-dir

  root-dir is the root directory to operate on

  [ -C | --cloud  ]:       do not configure a datasource.  incompatible with
                           options marked '[ds]'
  [ -i | --instance-id]:   instance-id for cloud-init, defaults to random [ds]
  [ -L | --nolocales ]:    Do not copy host's locales into container
  [ -S | --auth-key ]:     ssh public key file for datasource [ds]
  [ -u | --userdata ]:     user-data file for cloud-init [ds]

EOF
}

write_patched_start() {
    cat > "$1" <<"EOF"
#!/bin/bash
## This is a wrapper around upstart's /sbin/start to ensure that
## calling 'start' on a job after writing it to /etc/init will function
## correctly despite broken/missing support for inotify in overlayfs.
##
real() { exec -a /sbin/start "/sbin/start.real" "$@"; }

# no args or not root
[ $# -ne 0 -a "$UID" = "0" ] || real "$@"

job=""
# find first argument that doesn't start with '-' as 'job'
for x in "$@"; do
  [ "${x#-}" = "$x" ] && { job="$x"; break; }
done

# if job isn't there, no reason to check further
[ -n "$job" ] && [ -f "/etc/init/$job.conf" ] || real "$@"

# on Unknown, 'status' exits 1, and prints 'Unknown job' to stderr.
out=$(status "$@" 2>&1)
[ $? -eq 1 -a "${out#*nknown job}" != "$out" ] || real "$@"

initctl reload-configuration >/dev/null 2>&1
real "$@"
EOF
    chmod 755 "$1"
}

patch_start() {
    # patch /sbin/start inside root_d to deal with lack of inotify
    local root_d="$1"

    # already patched
    [ -f "$root_d/sbin/start.real" ] &&
        { debug 1 "$root_d 'start' seems already patched"; return 1; }

    debug 1 "patching /sbin/start in $root_d"
    chroot "$root_d" dpkg-divert --local --rename \
        --divert /sbin/start.real --add /sbin/start ||
        { error "failed to patch /sbin/start for overlayfs"; return 1; }

    write_patched_start "$root_d/sbin/start"
}

prep() {
    local short_opts="Chi:L:S:u:v"
    local long_opts="auth-key:,cloud,help,hostid:,name:,nolocales:,patch-start,userdata:,verbose"
    local getopt_out getopt_ret
    getopt_out=$(getopt --name "${0##*/}" \
        --options "${short_opts}" --long "${long_opts}" -- "$@" 2>/dev/null) ||
        :
    getopt_ret=$?
    if [ $getopt_ret -eq 0 ]; then
        eval set -- "${getopt_out}" ||
        { error "Unexpected error reading usage"; return 1; }
    fi

    local cur="" next=""
    local userdata="" hostid="" authkey="" locales=1 cloud=0 name=""
    local patch_start=0

    while [ $# -ne 0 ]; do
        cur="$1"; next="$2";
        case "$cur" in
            -C|--cloud) cloud=1;;
            -h|--help) prep_usage; return 0;;
               --name) name="$next";;
            -i|--hostid) hostid="$next";;
            -L|--nolocales) locales=0;;
               --patch-start) patch_start=1;;
            -S|--auth-key)
                [ -f "$next" ] ||
                    { error "--auth-key: '$next' not a file"; return 1; }
                authkey="$next";;
            -u|--userdata)
                [ -f "$next" ] ||
                    { error "--userdata: '$next' not a file"; return 1; }
                userdata="$next";;
            -v|--verbose) VERBOSITY=$((${VERBOSITY}+1));;
            --) shift; break;;
        esac
        shift;
    done

    [ $# -eq 1 ] || {
        prep_usage 1>&2;
        error "expected 1 arguments, got ($_LXC_HOOK) $#: $*";
        return 1;
    }

    local root_d="$1";

    if [ $getopt_ret -ne 0 -a "$_LXC_HOOK" = "clone" ]; then
        # getopt above failed, but we were called from lxc clone. there might
        # be multiple clone hooks and the args provided here not for us.  This
        # seems like not the greatest interface, so all we'll do is mention it.
        error "${0##*}: usage failed, continuing with defaults"
    fi

    [ "$patch_start" -eq 0 ] || patch_start "$root_d" ||
        { error "failed to patch start for overlayfs"; return 1; }

    local seed_d=""
    seed_d="$root_d/var/lib/cloud/seed/nocloud-net"
    if [ $cloud -eq 1 ]; then
        debug 1 "--cloud provided, not modifying seed in '$seed_d'"
    else
        if [ -z "$hostid" ]; then
            hostid=$(uuidgen | cut -c -8) && [ -n "$hostid" ] ||
                { error "failed to get hostid"; return 1; }
        fi
        mkdir -p "$seed_d" ||
            { error "failed to create '$seed_d'"; return 1; }

        echo "instance-id: lxc-$hostid" > "$seed_d/meta-data" ||
            { error "failed to write to $seed_d/meta-data"; return 1; }

        if [ -n "$authkey" ]; then
            {
                echo "public-keys:" &&
                sed -e '/^$/d' -e 's,^,- ,' "$authkey"
            } >> "$seed_d/meta-data"
            [ $? -eq 0 ] ||
                { error "failed to write public keys to metadata"; return 1; }
        fi

        local larch="usr/lib/locale/locale-archive"
        if [ $locales -eq 1 ]; then
            cp "/$larch" "$root_d/$larch" || {
                error "failed to cp '/$larch' '$root_d/$larch'";
                return 1;
            }
        fi

        if [ -z "$MIRROR" ]; then
            MIRROR="http://archive.ubuntu.com/ubuntu"
        fi

        if [ -n "$userdata" ]; then
            cp "$userdata" "$seed_d/user-data"
        else
            {
            local lc=$(locale | awk -F= '/LANG=/ {print $NF; }')
            echo "#cloud-config"
            echo "output: {all: '| tee -a /var/log/cloud-init-output.log'}"
            echo "apt_mirror: $MIRROR"
            echo "manage_etc_hosts: localhost"
            [ -z "$LANG" ] || echo "locale: $LANG";
            echo "password: ubuntu"
            echo "chpasswd: { expire: false; }"
            } > "$seed_d/user-data"
        fi
        [ $? -eq 0 ] || {
            error "failed to write user-data write to '$seed_d/user-data'";
            return 1;
        }
    fi

}

main() {
    # main just joins 2 modes of being called.  from user one from lxc clone
    local _LXC_HOOK
    if [ -n "$LXC_ROOTFS_MOUNT" -a "$3" = "clone" ]; then
        _LXC_HOOK="clone"
        local name="$1" pstart=""
        shift 3
        # if mountpoint is overlayfs then add '--patch-start'
        [ "${LXC_ROOTFS_PATH#overlayfs}" != "${LXC_ROOTFS_PATH}" ] &&
           pstart="--patch-start"
        debug 1 prep "--name=$name" $pstart "$LXC_ROOTFS_MOUNT" "$@"
        prep "--name=$name" $pstart "$LXC_ROOTFS_MOUNT" "$@"
    else
        _LXC_HOOK=""
        prep "$@"
    fi
    return $?
}

main "$@"

# vi: ts=4 expandtab