#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>

#define oops(m,x) { perror(m);exit(x);}

void main(int ac, char* av[])
{
    //dsfsdfsdfds
    int fd1, fd2;
    struct timeval timeout;
    fd_set readfds;
    int maxfd;
    int retval;

    if (ac != 4) {
        fprintf(stderr, "usage: %s file file timeout", *av);
        exit(1);
    }

    /** open files **/
    if ((fd1 = open(av[1], O_RDONLY)) == -1) {
        oops(av[1], 2);
    }
    if ((fd2 = open(av[2], O_RDONLY)) == -1) {
        oops(av[2], 3);
    }
    maxfd = 1 + (fd1 > fd2 ? fd1 : fd2);

    while (1) {
        FD_ZERO(&readfds);
        FD_SET(fd1, &readfds);
        FD_SET(fd2, &readfds);

        timeout.tv_sec = atoi(av[3]);
        timeout.tv_usec = 0;
        /** wait for input **/
        retval = select(maxfd, &readfds, NULL, NULL, &timeout);
        if (retval == -1) {
            oops("select", 4);
        }
        if (retval > 0) {
            if (FD_ISSET(fd1, &readfds)) {
                showdata(av[1], fd1);
            }
            if (FD_ISSET(fd2, &readfds)) {
                showdata(av[2], fd2);
            }
        } else {
            printf("no input after %d seconds\n", atoi(av[3]));
        }
    }
}

void showdata(char* fname, int fd)
{
    char buf[BUFSIZ];
    int n;

    printf(" %s: ", fname, n);
    fflush(stdout);

    n = read(fd, buf, BUFSIZ);
    if (n == -1) {
        oops(fname, 5);
    }
    write(1, buf, n);
    write(1, "\n", 1);
}