initramfs-suspend

#!/bin/sh
# Copyright 2013 Vianney le Clément de Saint-Marcq <vleclement@gmail.com>
# Copyright 2017 Zhongfu Li <me@zhongfu.li>
#
# This program 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; version 3 of the License.
#
# This program 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 This program.  If not, see http://www.gnu.org/licenses/.

cryptname="${1}"
YUBIKEY_LUKS_SLOT=2 #Set this in case the value is missing in /etc/ykluks.cfg

# Start udev from initramfs
/lib/systemd/systemd-udevd --daemon --resolve-names=never

# Sync one more time, just in case
sync

# Suspend root device
[ -z "${cryptname}" ] || cryptsetup luksSuspend "${cryptname}"

# Suspend the system
echo mem > /sys/power/state

# Resume root device
. /etc/ykluks.cfg

[ -z "${cryptname}" ] ||
    while true; do
        P1=$(/lib/cryptsetup/askpass "$WELCOME_TEXT")

        if [ "$HASH" = "1" ]; then
            P1=$(printf %s "$P1" | sha256sum | awk '{print $1}')
        fi

        R="$(printf %s "$P1" | ykchalresp -"$YUBIKEY_LUKS_SLOT" -i- 2>/dev/null || true)"

        if [ "$CONCATENATE" = "1" ]; then
            printf %s "$P1$R" | cryptsetup luksResume "${cryptname}" 2>&1;
        else
            printf %s "$R" | cryptsetup luksResume "${cryptname}" 2>&1;
        fi

        [ $? -le 1 ] && break
        sleep 2
    done

# Stop udev from initramfs, as the real daemon from rootfs will be restarted
udevadm control --exit