#!/bin/bash
#
# Copy a img.gz image file to a Compact Flash Card
#
# Copyright (C) 2009-2016 Lonnie Abelbeck
# This is free software, licensed under the GNU General Public License
# version 3 as published by the Free Software Foundation; you can
# redistribute it and/or modify it under the terms of the GNU
# General Public License; and comes with ABSOLUTELY NO WARRANTY.
#
# Input Arg1: diskN
# Input Arg2: img.gz or .img image file
#

if [ -z "$1" ]; then
  echo "Usage: os-x-cf-write diskN image_file.img.gz"
  diskutil list
  exit 1
fi
DISK="${1#/dev/}"

if [ "${DISK%[1-9]}" != "disk" ]; then
  echo "Usage: os-x-cf-write diskN image_file.img.gz"
  exit 1
fi

if [ -z "$2" ]; then
  echo "Usage: os-x-cf-write diskN image_file.img.gz"
  exit 1
fi
IMAGEFILE="$2"

if [ ! -f "$IMAGEFILE" ]; then
  echo "File: $IMAGEFILE, can not be found."
  echo "Exiting, no action performed."
  exit 1
fi

if ! diskutil list $DISK >/dev/null; then
  echo "Disk: $DISK, can not be found."
  echo "Exiting, no action performed."
  exit 1
fi

if diskutil list $DISK | grep -q "_HFS"; then
  echo "Disk: $DISK, does not appear to be a Flash Card."
  echo "Exiting, no action performed."
  exit 1
fi

if [ "$(id -u)" -ne 0 ]; then
  echo "Permission denied, run with 'sudo'"
  echo "Exiting, no action performed."
  exit 1
fi

if [ ! -e "/dev/r$DISK" ]; then
  echo "Device not found: /dev/r$DISK"
  echo "Exiting, no action performed."
  exit 1
fi

#
# Inputs look good, off to work...
#

diskutil unmountDisk $DISK

echo
echo "Erasing first 1 GB of /dev/$DISK..."
echo "This may take a long time..."

dd if=/dev/zero of=/dev/r$DISK bs=64k count=16000

echo
echo "Writing \"$IMAGEFILE\" to /dev/r$DISK"
echo "This may take a long time..."

if [ "${IMAGEFILE}" != "${IMAGEFILE%.gz}" ]; then
  gzcat "$IMAGEFILE" | dd of=/dev/r$DISK bs=64k
else
  dd if="$IMAGEFILE" of=/dev/r$DISK bs=64k
fi

echo
echo "Trying to eject $DISK..."
echo

cnt=5
while [ $cnt -gt 0 ]; do
  cnt=$((cnt - 1))
  sleep 2
  if diskutil eject $DISK; then
    echo "You can safely remove your $DISK."
    break
  fi
done