#!/bin/sh
#
# SPDX-License-Identifier: GPL-2.0-only
#

# 1MB blocksize
BLOCKSIZE=1048576

usage() {
	echo "Usage: $(basename $0) IMAGE DEVICE"
}

image_details() {
	IMG=$1
	echo "Image details"
	echo "============="
	echo "    image: $(basename $IMG)"
	# stat format is different on Mac OS and Linux
	if [ "$(uname)" = "Darwin" ]; then
		echo "     size: $(stat -L -f '%z bytes' $IMG)"
		echo " modified: $(stat -L -f '%Sm' $IMG)"
	else
		echo "     size: $(stat -L -c '%s bytes' $IMG)"
		echo " modified: $(stat -L -c '%y' $IMG)"
	fi
	echo "     type: $(file -L -b $IMG)"
	echo ""
}

device_details() {
	BLOCK_SIZE=512

	echo "Device details"
	echo "=============="

	# Collect disk info using diskutil on Mac OS
	if [ "$(uname)" = "Darwin" ]; then
		diskutil info $DEVICE | egrep "(Device Node|Media Name|Total Size)"
		return
	fi

	# Default / Linux information collection
	ACTUAL_DEVICE=`readlink -f $DEVICE`
	DEV=`basename $ACTUAL_DEVICE`
	if [ "$ACTUAL_DEVICE" != "$DEVICE" ] ; then
		echo "  device: $DEVICE -> $ACTUAL_DEVICE"
	else
		echo "  device: $DEVICE"
	fi
	if [ -f "/sys/class/block/$DEV/device/vendor" ]; then
		echo "  vendor: $(cat /sys/class/block/$DEV/device/vendor)"
	else
		echo "  vendor: UNKNOWN"
	fi
	if [ -f "/sys/class/block/$DEV/device/model" ]; then
		echo "   model: $(cat /sys/class/block/$DEV/device/model)"
	else
		echo "   model: UNKNOWN"
	fi
	if [ -f "/sys/class/block/$DEV/size" ]; then
		echo "    size: $(($(cat /sys/class/block/$DEV/size) * $BLOCK_SIZE)) bytes"
	else
		echo "    size: UNKNOWN"
	fi
	echo ""
}

check_mount_device() {
	if cat /proc/self/mounts | awk '{ print $1 }' | grep /dev/ | grep -q -E "^$1$" ; then
		return 0
	fi
	return 1
}

is_mounted() {
	if [ "$(uname)" = "Darwin" ]; then
		if df | awk '{ print $1 }' | grep /dev/ | grep -q -E "^$1(s[0-9]+)?$" ; then
			return 0
		fi
	else
		if check_mount_device $1 ; then
			return 0
		fi
		DEV=`basename $1`
		if [ -d /sys/class/block/$DEV/ ] ; then
			PARENT_BLKDEV=`basename $(readlink -f "/sys/class/block/$DEV/..")`
			if [ "$PARENT_BLKDEV" != "block" ] ; then
				if check_mount_device $PARENT_BLKDEV ; then
					return 0
				fi
			fi
			for CHILD_BLKDEV in `find /sys/class/block/$DEV/ -mindepth  1 -maxdepth 1 -name "$DEV*" -type d`
			do
				if check_mount_device /dev/`basename $CHILD_BLKDEV` ; then
					return 0
				fi
			done
		fi
	fi
	return 1
}

is_inuse() {
	HOLDERS_DIR="/sys/class/block/`basename $1`/holders"
	if [ -d $HOLDERS_DIR ] && [ `ls -A $HOLDERS_DIR` ] ; then
		return 0
	fi
	return 1
}

if [ $# -ne 2 ]; then
	usage
	exit 1
fi

IMAGE=$1
DEVICE=$2

if [ ! -e "$IMAGE" ]; then
	echo "ERROR: Image $IMAGE does not exist"
	usage
	exit 1
fi

if [ ! -e "$DEVICE" ]; then
	echo "ERROR: Device $DEVICE does not exist"
	usage
	exit 1
fi

if [ "$(uname)" = "Darwin" ]; then
	# readlink doesn't support -f on MacOS, just assume it isn't a symlink
	ACTUAL_DEVICE=$DEVICE
else
	ACTUAL_DEVICE=`readlink -f $DEVICE`
fi
if is_mounted $ACTUAL_DEVICE ; then
	echo "ERROR: Device $DEVICE is currently mounted - check if this is the right device, and unmount it first if so"
	device_details
	exit 1
fi
if is_inuse $ACTUAL_DEVICE ; then
	echo "ERROR: Device $DEVICE is currently in use (possibly part of LVM) - check if this is the right device!"
	device_details
	exit 1
fi

if [ ! -w "$DEVICE" ]; then
	echo "ERROR: Device $DEVICE is not writable - possibly use sudo?"
	usage
	exit 1
fi

image_details $IMAGE
device_details

printf "Write $IMAGE to $DEVICE [y/N]? "
read RESPONSE
if [ "$RESPONSE" != "y" ]; then
	echo "Write aborted"
	exit 0
fi

echo "Writing image..."
if which pv >/dev/null 2>&1; then
	pv "$IMAGE" | dd of="$DEVICE" bs="$BLOCKSIZE"
else
	dd if="$IMAGE" of="$DEVICE" bs="$BLOCKSIZE"
fi
sync