poll-demo.c

// <poll.h> demo
//
// in response to: https://boards.4channel.org/g/thread/70651197#p70656634
//
// see: http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/poll.h.html
//      http://man7.org/linux/man-pages/man2/poll.2.html (more helpful)

#include <stdio.h>
#include <stdlib.h>
#include <string.h> // strchr(), strerror()
#include <errno.h>

#include <poll.h>

#define BUFFSZ 1024
char buffer[BUFFSZ];

#define len(array) (sizeof(array) / sizeof(array[0]))

#define HIGHLIGHT "\033[2m"
#define NORMVIDEO "\033[0m"

int main() {
    struct pollfd p[1];
    int whatever;

    p[0].fd = fileno(stdin);
    p[0].events = (POLLIN | 0);

    whatever = 0;

    while(1) {
        poll(p, len(p), 3); // 3 milli-second timeout

        if(p[0].revents == POLLIN) {
            char *line = fgets(buffer, sizeof(buffer)-1, stdin);

            // error handling...

            if(!line) {
                int err = errno;
                fprintf(stderr, "[err=%d] msg=%s\n", err, strerror(err));
                exit(1);
            }

            // process input...

            char *n = strchr(line, '\n');
            if(n) *n = '\0';

            printf("You entered: '%s%s%s', cycle == %d\n",
                                 HIGHLIGHT, line, NORMVIDEO, whatever);
        }
        else {

            // other non-input activities...
            whatever++;
        }
    }
    return 0;
}