#include <stdio.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

struct transfer_range{
 __u32 dest_fd;
 __u32 start_block;
 __u32 length;
};

#define EXT4_IOC_TRANSFER_BLOCK_RANGE	_IOW('f', 19, struct transfer_range)

int main(int argc, char ** argv)
{
	int dfd, fd;
	struct transfer_range tr;

	if(argc != 5){
		printf("Usage: <sourcefile> <destfile> <startblock> <length>\n");
		return 0;
	}

	memset(&tr, 0, sizeof(struct transfer_range));
	tr.start_block = atoi(argv[3]);
	tr.length = atoi(argv[4]);

	fd = open(argv[1],O_RDWR ,0666);
	if (!fd) {
		printf("Cannot open source file\n");
		_exit(1);
	}

	dfd = open(argv[2],O_RDWR|O_CREAT ,0666);
	if (!dfd) {
		printf("Cannot open dest file\n");
		_exit(1);
	}

	tr.dest_fd = dfd;
	ioctl(fd, EXT4_IOC_TRANSFER_BLOCK_RANGE, &tr);
	close(fd);
	close(dfd);
	perror("Return:\n");
	return 0;
}