Script for detecting and mounting flash storage early in the lifecycle

automan.sh

#!/usr/bin/env bash

DEVICE=/dev/sda1

DEVICE_MOUNTED=""
get_device_mounted() {
	MOUNTED_DIR=$(find /media/pi/ -maxdepth 1 -type d -printf '%f\n' | grep "-")
	if [ -z "$MOUNTED_DIR" ]; then
	  DEVICE_MOUNTED=""
	else
	  DEVICE_MOUNTED=true
	fi
}

wait_for_device_mounted() {
  echo "Waiting for device mount"
  get_device_mounted
  while [ -z "$DEVICE_MOUNTED" ]; do
    sleep 0.1
    get_device_mounted
  done
  echo "Device is mounted"
}


wait_for_device_insertion() {
  echo "Waiting for block device..."
  rm /tmp/device_block
  touch /tmp/device_block
  # This roundabout trick helps with buffering stdout, dunno why
  dmesg -W | grep --line-buffered "Attached SCSI removable disk" -m 1 >> /tmp/device_block &
  #dmesg -W | grep --line-buffered "sda: detected capacity change from 0" -m 1 >> /tmp/device_block &
  tail -f -n1 /tmp/device_block | head -n 1
  echo "Device found."
}

DEVICE_AUTOSTART=""
get_device_autostart() {
	DEVICE_AUTOSTART=$(find /media/pi/*/autostart.sh -maxdepth 1 -type f)
}

DEVICE_AUTOKILL=""
get_device_autokill() {
	DEVICE_AUTOKILL=$(find /media/pi/*/autokill.sh -maxdepth 1 -type f)
}

wait_for_device_removal() {
  # If there is an autokill script on the disk, back it up
  # so it can be ran if the disk is unsafely removed
  get_device_autokill
  echo $DEVICE_AUTOKILL
  if test -f "$DEVICE_AUTOKILL"; then
    echo "Backing up kill script..."
    cp "$DEVICE_AUTOKILL" /tmp/autokill.sh
  fi

  # Then we wait for the drive to disappear
  while test -f "$DEVICE_AUTOKILL"; do
    echo "Waiting on catridge removal..."
    sleep 1
  done
}

AUTOSTART_ALIVE=""
get_autostart_alive() {
	if ! [ -z "$AUTOSTART_PID" ]; then
	  if ps -p $AUTOSTART_PID > /dev/null; then
	    AUTOSTART_ALIVE=true
	  else
	    AUTOSTART_ALIVE=""
	  fi
	fi
}

wait_for_exit() {
	while true; do
	   sleep 0.2
	  get_autostart_alive
	
	  if [ -z "$AUTOSTART_ALIVE" ]; then
	    echo "Process exit (soft)"
	    break
	  fi
	
	  get_device_mounted
	  if [ -z "$DEVICE_MOUNTED" ]; then
	    echo "Process exit (force)"
	    break
	  fi
    done
}


autokill() {
  if [ -f "/tmp/autokill.sh" ]; then
    
    echo "Invoking autokill.sh"
	chmod +x /tmp/autokill.sh
	sh /tmp/autokill.sh 
	rm /tmp/autokill.sh
  fi
  
  get_autostart_alive
  if ! [ -z "$AUTOSTART_ALIVE" ]; then
    echo "Killing $AUTOSTART_PID"
    kill $AUTOSTART_PID
  fi
}

DEVICE_VALID=""
get_device_valid() {
  get_device_autostart

  if [ -f "$DEVICE_AUTOSTART" ]; then
    DEVICE_VALID=true
  else
    DEVICE_VALID=""
  fi
}

autostart() {
  get_device_autokill
  if test -f "$DEVICE_AUTOKILL"; then
    echo "Backing up autokill before autostart..."
    cp "$DEVICE_AUTOKILL" /tmp/autokill.sh
  fi
  
  echo "Running" $DEVICE_AUTOSTART
  sleep 0.5
  sudo su pi -c "sh $DEVICE_AUTOSTART" &
  AUTOSTART_PID=$!
  echo "Watch PID $AUTOSTART_PID"
}


autokill
while :
do
  wait_for_device_insertion
  wait_for_device_mounted
  
  get_device_valid
  if ! [ -z "$DEVICE_VALID" ]; then
    autostart
  else
    echo "Rejecting disk, no autostart"
  fi
  
  wait_for_exit
  autokill
done