initramfs-init

#!/bin/busybox sh

# This is the init script built into the PrawnOS initramfs

# This file is part of PrawnOS (https://www.prawnos.com)
# Copyright (c) 2018 Hal Emmerich <hal@halemmerich.com>

# PrawnOS is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2
# as published by the Free Software Foundation.

# PrawnOS 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 PrawnOS.  If not, see <https://www.gnu.org/licenses/>.


#add this to start shell at desired point
rescue_shell() {
    [ "{$1}" == "debug" ] && echo "Debug flag detected, entering debug shell" > /dev/tty1
    echo "Something went wrong. Dropping to a shell." > /dev/tty1
    exec setsid /bin/sh -c 'exec /bin/sh </dev/tty1 >/dev/tty1 2>&1'
}

#used to parse the kernel cmdline
cmdline() {
    local value
    value=" $(cat /proc/cmdline) "
    value="${value##* ${1}=}"
    value="${value%% *}"
    [ "${value}" != "" ] && echo "${value}"
}

#used to get the uuid of the root partiton since findfs isn't in debian busybox-static
rootpartuuid() {
    local value
    value=$1
    value="${value%/*}"
    value="${value#*=}"
    [ "${value}" != "" ] && echo "${value}"
}

# a clever portable shell script to detect occurances of a substring in a string
# occur <string> <substring> (optional count)
# if optional count is not provided:
# returns 1 if substring is not in string
# returns 0 otherwise
# if optional count is provided:
# returns 1 if substring occurs in string < optional count
# returns 0 otherwise
occur() while case "$1" in (*"$2"*) set -- \
        "${1#*"$2"}" "$2" "${3:-0}" "$((${4:-0}+1))";;
        (*) return "$((${4:-0}<${3:-1}))";;esac
        do : "${_occur:+$((_occur=$4))}";done

# mount the bare necesities
mount -n -t proc     proc      /proc
mount -n -t sysfs    sysfs     /sys
mount -n -t devtmpfs devtmpfs  /dev

# get the root device, so we can find the boot partiton
UNPARSED=$(cmdline root)
ROOT_PARTUUID=$(rootpartuuid $UNPARSED)
BLKID=$(/sbin/blkid | grep $ROOT_PARTUUID )
#If its an mmcblk device, the kernel partiton will p1. If it is a usb device, the partiton will just be 1
#Just want everything before the 1
ROOT_DEV="${BLKID%1:*}"


# happens when kernel takes its time looking for devices
if [ -z ${ROOT_DEV} ]
then
    sleep 1
    # get the root device, so we can find the boot partiton
    UNPARSED=$(cmdline root)
    ROOT_PARTUUID=$(rootpartuuid $UNPARSED)
    BLKID=$(/sbin/blkid | grep $ROOT_PARTUUID )
    #If its an mmcblk device, the kernel partiton will p1. If it is a usb device, the partiton will just be 1
    ROOT_DEV="${BLKID%1:*}"
    # if device is still not seen, bail out
    [ -z ${ROOT_DEV} ] && rescue_shell
fi


# label any partition on the system with RESCUESHELL to enter the initramfs rescue shell before mount and root_switch.
# you can do this with "cgpt add -i 1 -l RESCUESHELL /dev/sda" for example to label the first partiton of a usb drive.
if [ -n "$(blkid | grep RESCUESHELL)" ]
then
    rescue_shell debug
fi


if [ -n "$(blkid ${ROOT_DEV}2 | grep crypto_LUKS)" ]
then
    #decrypt and mount the root filesystem, disable kernel log messages to avoid clashing with the prompt
    dmesg -n 2
    echo "Opening encrypted root partition, this will take 30s..."
    cryptsetup --tries 5 luksOpen ${ROOT_DEV}2 luksroot || rescue_shell
    mount /dev/mapper/luksroot /newroot
else
    # mount the unencrypted root filesystem
    [ -d "/newroot" ] || mkdir -p /newroot
    mount ${ROOT_DEV}2 /newroot
fi

dmesg -n 1
echo -e '\033[?17;0;0c' > /dev/tty1 # magically make cursor disappear
dd status=none if=/newroot/PrawnOS-$(cat /sys/class/graphics/fb0/virtual_size | tr ',' 'x') of=/dev/fb0 # write splash to framebuffer

umount /sys
umount /proc

#switch to the new rootfs
exec switch_root /newroot /sbin/init