serial port write in c

serialwrite.c

#include <stdio.h>   /* Standard input/output definitions */
#include <string.h>  /* String function definitions */
#include <unistd.h>  /* UNIX standard function definitions */
#include <fcntl.h>   /* File control definitions */
#include <errno.h>   /* Error number definitions */
#include <termios.h> /* POSIX terminal control definitions */
#include <stdlib.h>	 /* Int to string conversion */


int open_port(char *port)
{
	int fd;

	fd = open(port, O_RDWR | O_NOCTTY | O_NDELAY);
	if(fd == -1){
		//could not open port
		perror("open_port: unable to open port");
	} else {
		fcntl(fd, F_SETFL, 0);
	}
	return (fd);
}

int write_data(int fd, char *data, int bytes)
{
	int n;

	n = write(fd, data, bytes);
	if(n < 0){
		perror("write() of byte failed!\n");
	}

	return n;
}

void close_port(int fd)
{
	close(fd);
	return;
}

serialwrite.h

/* open the port specified by port. return file handle */
int open_port(char *port);

/* write data of size bytes to fd. return number of bytes written */
int write_data(int fd, char* data, int bytes);

/* close port specified by fd */
void close_port(int fd);