Code to open a TTY with POSIX API, raw mode

tty.c

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

#define BAUD B19200

int open_port()
{
    int fd;

    fd = open("/dev/ttyS1", O_RDWR | O_NOCTTY);
    if (fd == -1)
    {
        perror("Unable to open /dev/ttyS1: ");
        exit(1);
    }
    printf("opened port\n");

    int ret;
    struct termios ts;
    
    bzero(&ts, sizeof(ts));
    cfmakeraw(&ts);
    cfsetspeed(&ts, BAUD);
    ts.c_cflag |= (CLOCAL | CREAD | CSTOPB);
    tcflush(fd, TCIOFLUSH);

    ret = tcsetattr(fd, TCSANOW, &ts);
    if (ret == -1)
    {
        perror("tcsetattr: ");
        exit(1);
    }
    printf("set attrs\n");

    return fd;
}

int main(void)
{
    int fd = open_port();
    uint8_t c;

    while (read(fd, &c, 1) >= 0)
        write(STDOUT_FILENO, &c, 1);

    perror("read: ");
    exit(1);
}