swap_to

#!/bin/sh 
# swap_to a different image on the SD Card, while keeping a backup
# usage:
# swap_to directory_name

if [ `id -u` != "0" ] ; then
   echo "This script must be run as root" 1>&2
   exit 1
fi

if [ "$(grep mmcblk0p1 /proc/mounts | wc -l)" -eq "0" ] ; then
	mount /dev/mmcblk0p1 /media/boot
fi

DIR=$(grep mmcblk0p1 /proc/mounts | awk '{print $2}')

if [ $(cat /proc/cpuinfo | grep -i zynq | wc -l) -gt 0 ] ; then
	ZYNQ=1
fi

if [ -z ${1} ] ; then
	if [ "${ZYNQ}" = "1" ] ; then
		ls -d ${DIR}/zynq*
	else
		ls -d ${DIR}/
	fi
fi

find_match () {
	needle=$(basename $1)
	match=$(md5sum -b $1|awk '{print $1}')
	haystack_dir=$(dirname $1)
	for i in $(find ${haystack_dir} -mindepth 2 -name ${needle}) ; do
		temp=$(md5sum -b $i|awk '{print $1}')
		if [ "${temp}" = "${match}" ] ; then
			echo not backing up ${needle}, match ${i}
			return
		fi
	done
	echo making backup of $1 in ${DIR}/backup_swap_from
	mkdir -p ${DIR}/backup_swap_from
	cp ${1} ${DIR}/backup_swap_from/
}

missing_file() {
	echo missing file $1
	echo SD card may not be bootable
	exit
}

if [ ! -z ${1} ] ; then
	if [ -d ${DIR}/${1} ] ; then
		# if they are not on the drive, back them up
		echo "### backing up existing files ###"
		find_match ${DIR}/BOOT.BIN
		find_match ${DIR}/devicetree.dtb
		find_match ${DIR}/uImage

		echo
		echo "### copying files to BOOT partion ###"

		if [ -f ${DIR}/${1}/BOOT.BIN ] ; then
			echo copying ${DIR}/${1}/BOOT.BIN
			cp ${DIR}/${1}/BOOT.BIN ${DIR}/
		else
			missing_file BOOT.BIN
		fi
		if [ -f ${DIR}/${1}/devicetree.dtb ] ; then
			echo copying ${DIR}/${1}/devicetree.dtb
			cp ${DIR}/${1}/devicetree.dtb ${DIR}/
		else
			missing_file devicetree.dtb
		fi
		if [ -f ${DIR}/${1}/uImage ] ; then
			echo copying ${DIR}/${1}/uImage
			cp ${DIR}/${1}/uImage ${DIR}/
		else
			if [ "${ZYNQ}" = "1" ] ; then
				echo copying ${DIR}/zynq-common/uImage
				cp ${DIR}/zynq-common/uImage ${DIR}/
			fi
		fi
	else
		echo could not find ${DIR}/${1}
	fi
fi
umount $DIR