#include <stdio.h>
#include <error.h>
#include <errno.h>
#include <sys/select.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
#include <sys/ioctl.h>

int main(int argc, char * argv[])
{
    fd_set rfds;
    struct timeval tv;
    char data[256];
    int retval;
    int fd;
    struct termios config;
    
    if (argc < 2)
        error(-1, 0, "need a port");
    fd = open(argv[1], O_RDWR | O_NONBLOCK | O_NOCTTY);
    if (fd < 0)
        error(-1, errno, "failed to open %s", argv[1]);

    if(tcgetattr(fd, &config) < 0)
        error(-1, errno, "tcgetattr failed");

    config.c_cc[VMIN]  = 100;
    config.c_cc[VTIME] = 2;
    
    if(tcsetattr(fd, TCSANOW, &config) < 0)
        error(-1, errno, "tcsetattr failed");

    while (1)
    {
        FD_ZERO(&rfds);
        FD_SET(fd, &rfds);
    
        tv.tv_sec = 1;
        tv.tv_usec = 0;
    
        retval = select(fd+1, &rfds, NULL, NULL, &tv);
    
        if (retval == -1)
            perror("select()");
        else if (retval)
        {
            int nb;
            retval = ioctl(fd, TIOCINQ, &nb);
            if (retval)
                error(-1, errno, "ioctl(TIOCINQ) failed");
            else
                fprintf(stdout,"nb=%d\n",nb);
       
            for (int i=0;i<10;i++)
            {
                retval = read(fd, data, 100);
                if (retval < 0 && errno == EAGAIN)
                {
                    fprintf(stdout,"read() returned EAGAIN\n");
                    usleep(100000);
                    continue;
                }
                else if (retval >= 0)
                {
                    retval = fwrite(data,1,retval,stdout);
                    break;
                }
                else
                {
                    error(-1, errno, "%d = read() failed", errno);
                }
            }
        }
        else
            printf("No data...\n");
    }
           
    close(fd);
    return 0;
}