#include <sys/sendfile.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <stdio.h>

int main (int argc, char *argv[])
{
	int in, out;
	struct stat st;
	off_t off = 0;
	ssize_t rc;

	in = open("test.data", O_RDONLY);
	if (in < 0) {
		perror("test.data read");
		return 1;
	}

	fstat(in, &st);

	out = open("test.data", O_WRONLY);
	if (out < 0) {
		perror("test.data write");
		return 1;
	}

	rc = sendfile(out, in, &off, st.st_size);
	if (rc < 0) {
		perror("sendfile");
		close(in);
		unlink("out");
		close(out);
		return 1;
	}

	close(in);
	close(out);
	return 0;
}