#!/bin/sh
# mkoverlay - Create ext2 disk image to use for ovpkg
# Thanks: http://wiki.osdev.org/Loopback_Device

echo -e "mkoverlay - Creates ext2 disk image\n\t    for use with ovpkg"

USAGE=0
# Check is first arg is number only (size)
if [ -n "$( echo $1 | sed 's/^[+-]//;s/[0-9]//g;s/\.//')" ]; then
	echo "Invalid size"
	USAGE=1
fi

# Check that 2nd arg is a correct path
DIR=`echo $2 | sed 's/\(.*\)\/.*/\1/'`
if [ ! -d ${DIR} ]; then
	echo "Invalid path"
	USAGE=1
fi

# Check if file already exists
if [ -f ${2} ]; then
	echo "File already exists"
	USAGE=1
fi

# if either input arg is not correct, exit
if [ $USAGE -eq 1 ]; then
	echo "Usage: mkoverlay <size> <imagefile>
	size: Size of image file in megabytes (without Mb string)
	imagefile: full path and filename of image file"
	exit 1
fi
 
SIZE=$1
IMG_FILE=$2
let CYL=${SIZE}*1000*1024/516096

echo "Creating $SIZE Mb image file at $IMG_FILE"
dd if=/dev/zero of=${IMG_FILE} bs=516096c count=${CYL} &> /dev/null

echo "Partitioning the image file"
echo -e -n "o\nn\np\n1\n\n\nw\n" | fdisk -u -C${CYL} -S63 -H16 ${IMG_FILE} &> /dev/null

LOOPDEV=`losetup -f`
echo "Mounting the image file to $LOOPDEV"
losetup -o32256 ${LOOPDEV} ${IMG_FILE}

echo "Formatting the image file"
mke2fs -b1024 ${LOOPDEV} &> /dev/null

losetup -d ${LOOPDEV}
echo "SD_ROOTFS=$IMG_FILE" > /etc/ovpkg.conf
echo "Done!"