#define _POSIX_C_SOURCE 200112L

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

int main(int argc, char* argv[]) {
    if (argc < 2) {
	fprintf(stderr, "usage: %s <filename>", argv[0]);
	exit(EXIT_FAILURE);
    }

    int fd = -1;
    if ((fd = open(argv[1], O_WRONLY | O_CREAT, S_IRWXU)) < 0) {
	perror("open");
	exit(EXIT_FAILURE);	
    }

    char* newname = malloc(strlen(argv[1]) + 3);
    strcpy(newname, argv[1]);
    strcat(newname, ".r");
    
    int fd2 = -1;
    if ((fd2 = open(newname, O_RDONLY | O_CREAT, S_IRWXU)) < 0) {
	perror("open2");
	exit(EXIT_FAILURE);	
    }

    // close(fd2);
    
    if (rename(argv[1], newname) < 0) {
	perror("rename");
	exit(EXIT_FAILURE);		
    }

    
    return EXIT_SUCCESS;
}