int ifd = open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
if(!ifd) {
fprintf(stderr, "Could not create invitation file %s: %s\n", filename, strerror(errno));
int ifd = open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
if(!ifd) {
fprintf(stderr, "Could not create invitation file %s: %s\n", filename, strerror(errno));