write_image

#!/bin/sh
# Write the turtlebot3 image to desk and
# perform post-writing steps that do not require a boot
# TODO: Make a good interface for this script


# The raspberry pi image location
raspi_image=$1

# The sdcard device (e.g. /dev/mmcblk0).
sdcard_dev=$2

# Hostname for the turtlebot
turtlebot_name=$3

# Public key, used to access the turtlebot
public_key=$4

# The network connection profile. If it is called <something>.robot.nmconnection it will use 
# robotdns (https://github.com/m-elwin/robotdns)
if [ -f "$5" ] # if the specified file does not exist, search in /etc/NetworkManager/system-connections
then
    nmconnection=$5
else
    nmconnection="/etc/NetworkManager/system-connections/${5}.nmconnection"
fi

# The address of the robotdns server (or blank if not using robotdns).
# If using robotdns, the network connection profile must already be a valid robotdns profile and be named <something>.robot.nmconnection
robotdns=$6

# user id of the msr user. This is always the same when we create the image, and we need it to change ownership
# (or we'd have to proot in)
msr_uid=1000

# compute the partitions of the device.
# naming convention depends on if they end
# in a letter or a number. 
if [ $(expr ${sdcard_dev} : '.*[0-9]') = 0 ]
then
    # block device name not end in number
    sdcard_bootpart=${sdcard_dev}1
    sdcard_ospart=${sdcard_dev}2
else
    # block device name ends in number
    sdcard_bootpart=${sdcard_dev}p1
    sdcard_ospart=${sdcard_dev}p2
fi

sudo umount $sdcard_bootpart 
sudo umount $sdcard_ospart 

echo "Writing the image (takes some time)"
sudo dd bs=4M if=$raspi_image of=$sdcard_dev conv=fsync oflag=direct status=progress

echo "Expanding partition"
sudo parted $sdcard_dev resizepart 2 100%
sudo e2fsck -fy $sdcard_ospart
sudo resize2fs $sdcard_ospart

echo "Mounting the sd card"
mkdir -p /tmp/raspi
sudo mount $sdcard_ospart /tmp/raspi

echo "Setting hostname to $turtlebot_name"
echo $turtlebot_name | sudo tee /tmp/raspi/etc/hostname
echo "127.0.1.1 $turtlebot_name" | sudo tee -a /tmp/raspi/etc/hosts

echo "Copying the public key"
sudo mkdir -p /tmp/raspi/home/msr/.ssh
sudo cp $public_key /tmp/raspi/home/msr/.ssh/authorized_keys
sudo chown $msr_uid:$msr_uid /tmp/raspi/home/msr/.ssh/authorized_keys

# Install the network connection, while automatically removing uuid or wifi interface names
echo "Installing the network connection profile"
robot_nmfile=/tmp/raspi/etc/NetworkManager/system-connections/$(basename $nmconnection)
sudo grep -v "uuid=\|interface-name=" $nmconnection | sudo tee $robot_nmfile
sudo chmod 600 $robot_nmfile

if [ ! -z "$robotdns" ]
then
    # create the settings file
    echo "export nmconnect=$(basename $nmconnection | cut -d'.' -f 1)" | sudo tee ${robot_nmfile}.settings
    echo "export dnshost=$robotdns" | sudo tee -a ${robot_nmfile}.settings
    echo "export user_home=/home/msr" | sudo tee -a ${robot_nmfile}.settings
    sudo chmod 600 ${robot_nmfile}.settings

    # Generate the ssh key and install it
    rm -f /tmp/id_robotdns.pub /tmp/id_robotdns
    ssh-keygen -t ed25519 -C $turtlebot_name -f /tmp/id_robotdns -q -N ""
    sudo mv /tmp/id_robotdns /tmp/raspi/home/msr/.ssh/
    sudo cp /tmp/id_robotdns.pub /tmp/raspi/home/msr/.ssh/
    sudo chown $msr_uid:$msr_uid /tmp/raspi/home/msr/.ssh/id_robotdns
    sudo chown $msr_uid:$msr_uid /tmp/raspi/home/msr/.ssh/id_robotdns.pub

    # install the fingerprint
    ssh-keyscan -H $robotdns | sudo tee /tmp/raspi/home/msr/.ssh/known_hosts
    sudo chown $msr_uid:$msr_uid /tmp/raspi/home/msr/.ssh/known_hosts
    cp /tmp/raspi/home/msr/.ssh/id_robotdns.pub /tmp/id_robotdns.pub
    echo "Send /tmp/id_robotdns.pub to your system administrator so the robot can access the robotdns server"
fi

sudo umount /tmp/raspi