#include <signal.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>

static sig_atomic_t exitflag = 0;

static void interrupt(int sig)
{
    exitflag = 1;
}

int main()
{
    struct sigaction sa;
    sigaction(SIGHUP, NULL, &sa);
    sa.sa_handler = interrupt;
    sa.sa_flags &= ~SA_RESTART;
    sigaction(SIGHUP, &sa, NULL);

    while (!exitflag) {
        char buf[1024];
        int l = read(0, buf, sizeof(buf));
        if (l == -1) {
            if (errno == EINTR || errno == EAGAIN) {
                perror("read");
                continue;
            }
            break;
        } else if (l == 0) {
            break;
        }
        write(1, buf, l);
    }
    return 0;
}