#include <stdio.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <stdbool.h>

#ifdef EOT
#undef EOT
#endif
#define EOT 4

/*
 *  @fn non_blocking_input(int fileno, bool enable)
 *  @brief For enable or disabling non-blocking input on the specified stream.
 *  @param fileno - file number of stream to alter
 *  @param enable - set to true or false
 */
int non_blocking_input(int fileno, bool enable)
{
    static struct termios old;

    if (enable)
    {
        struct termios tmp;

        if (tcgetattr(fileno, &old))
        {
            return -1;
        }

        memcpy(&tmp, &old, sizeof(old));

        tmp.c_lflag &= ~ICANON & ~ECHO;

        if (tcsetattr(fileno, TCSANOW, (const struct termios*) &tmp))
        {
            return -1;
        }
    }
    else
    {
        tcsetattr(fileno, TCSANOW, (const struct termios*) &old);
    }

    return 0;
}


int main()
{
    // enable non-blocking input
    non_blocking_input(STDIN_FILENO, true);

    printf("Enter a sentence ending with a .:\n");

    int ch = EOT;

    // read single character until a '.' is read; a ctrl-D is interpreted as
    // an EOT (End Of Transmission).
    while (((ch = getchar()) != EOT) && (ch != '.'))
    {
        putchar(ch);
    }
    if (ch != EOT)
    {
        puts(".");
    }

    // re-enable blocking input
    non_blocking_input(STDIN_FILENO, false);

    return 0;
}