ttyACM problem

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <iostream>
#include <sys/poll.h>
#include <vector>


int open(const char *device)
{
    tcflag_t bitrate = B115200;
    int fd = ::open( device, O_RDWR | O_NOCTTY );
    if ( fd < 0 )
    {
        fprintf( stderr, "Failed to open serial device '%s' (errno: %s)\n", device, strerror(errno) );
        return -1;
    }
    if (::ioctl(fd, TIOCEXCL))
    {
        fprintf( stderr, "Failed to lock serial device '%s' (errno: %s)\n", device, strerror(errno) );
        return -1;
    }



    // Check if device is a terminal device
    if ( !isatty( fd ) )
    {
        fprintf( stderr, "Device '%s' is not a terminal device (errno: %s)!\n", device, strerror(errno) );
        ::close( fd );
        return -1;
    }

    struct termios settings;
    // Set input flags
    settings.c_iflag =  IGNBRK          // Ignore BREAKS on Input
                     |  IGNPAR;         // No Parity
                                        // ICRNL: map CR to NL (otherwise a CR input on the other computer will not terminate input)

    // Set output flags
    settings.c_oflag = 0;               // Raw output

    // Set controlflags
    settings.c_cflag = bitrate
                     | CS8              // 8 bits per byte
                     | CSTOPB           // Stop bit
                     | CREAD            // characters may be read
                     | CLOCAL;          // ignore modem state, local connection

    // Set local flags
    settings.c_lflag = 0;               // Other option: ICANON = enable canonical input

    // non-canonical mode: set device to non blocking mode:
    // Set timer
    settings.c_cc[VTIME] = 0;           // 0 means timer is not used

    // Set minimum bytes to read
    settings.c_cc[VMIN]  = 0;           // 1 means wait until at least 1 character is received; 0 means don't wait

    // Now clean the modem line and activate the settings for the port
    tcflush( fd, TCIFLUSH );
    tcsetattr( fd, TCSANOW, &settings );
    return fd;
}

int readAll(int fd)
{
    unsigned char buf[256];
    int res;
    int count = 0;
    while(1)
    {
        res = read( fd, &buf, 100 );
        if (res == 0) return count;
        if (res < 0) return -1;
        count += res;
        //printf("res = %d\n", res);
    }
}

void readSleepLoop(int fd1, int fd2)
{
    printf("start readSleepLoop\n");

    for(int n = 0; n < 10000; n++)
    {
        readAll(fd1);
        readAll(fd2);
        usleep(1);
    }
}

void readPollLoop(int fd)
{
    struct pollfd fds[1];
    fds[0].fd = fd;
    fds[0].events = POLLIN ;
    while(1)
    {
        int pollrc = poll( fds, 1, 1000);
        if (pollrc < 0)
        {
            perror("poll");
        }
        else if( pollrc > 0)
        {
            if( fds[0].revents & POLLIN )
            {
                unsigned char buff[256];
                int res = read(fd, buff, sizeof(buff) );
                if (res > 0)
                {
                    //printf("res = %d\n", res);
                }
            }
        }
    }
}

void readSelectLoop(int fd)
{
    fd_set rfds;
    struct timeval tv;
    int retval;
    printf("starting readSelectLoop\n");
    while(1)
    {
        tv.tv_sec = 1;
        tv.tv_usec = 0;
        FD_ZERO(&rfds);
        FD_SET(fd, &rfds);
        retval = select(fd + 1, &rfds, NULL, NULL, &tv);
        //printf("retval = %d\n", retval);
        if (retval < 0)
        {
            perror("select()");
        }
        else if (retval > 0)
        {
            unsigned char buff[256];
            int res = read(fd, buff, sizeof(buff) );
            if (res > 0)
            {
                //printf("res = %d\n", res);
            }
        }
    }
}

int main(int argc, char* argv[])
{
    int fd1 = open("/dev/ttyACM0");
    int fd2 = open("/dev/ttyACM1");
    if(fd1 < 0 || fd2 < 0)
    {
        return -1;
    }
    //readSleepLoop(fd1, fd2);
    readPollLoop(fd1);
    //readSelectLoop(fd1);
    close(fd1);
    close(fd2);
}