#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#define SZBUF 256
int main(int argc, char *argv[]){
	int fs, fd, m, n;
	char buf[SZBUF];
	if (argc < 3){
		fprintf(stderr, "Usage : %s <SRC_FILE> <DST_FILE>\n", argv[0]);
		exit(1);
	}
	fs = open(argv[1], O_RDONLY);
	if (fs == -1){
		perror("Opening source file fails");
		exit(2);
	}
	fd = open(argv[2], O_WRONLY|O_TRUNC|O_CREAT, 0600);
	if (fd == -1){
		perror("Opening destination file fails");
		exit(3);
	}
	while (n = read(fs, buf, SZBUF)){
		m = write(fd , buf, n);
		if (n == -1){
			perror("Writing in file fails");
			exit(4);
		}
	}
	close(fd);
	close(fs);
	exit(0);
	return EXIT_SUCCESS;
}