#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <time.h>
#include <signal.h>
#include <poll.h>
#define NUM 4
#define errExit(msg)    do { perror(msg); _exit(EXIT_FAILURE); } while (0)
#define errExit1(msg)    { perror(msg); _exit(EXIT_FAILURE); } 

void child_handler(int sig) {
    pid_t pid;
    while((pid = waitpid(-1, NULL, WNOHANG)) > 0);
}

void int_handler(int sig){
   printf("Ctrl-C pressed, do nothing...\n");
}

int main(int argc, char *argv[]) {

  struct sigaction new_act, old_act;
  sigemptyset (&new_act.sa_mask);
  new_act.sa_flags = 0;
  new_act.sa_flags = SA_RESTART;
  new_act.sa_handler = child_handler;

  sigaction (SIGCHLD, &new_act, &old_act);

  struct sigaction nint_act, oint_act;
  sigemptyset (&nint_act.sa_mask);
  nint_act.sa_flags = 0;
  nint_act.sa_flags = SA_RESTART;
  nint_act.sa_handler = int_handler;

  sigaction (SIGINT, &nint_act, &oint_act);

  int pipefd[NUM][2];
  pid_t cpid[NUM];

  int nfds, num_open_fds;
  struct pollfd *pfds;
  int ready;

  unsigned char i,tt;
  char buf;
  int rr;

  if (argc != 2) {
     fprintf(stderr, "Usage: %s <string>\n", argv[0]);
     _exit(EXIT_FAILURE);
  }

  srand(time(NULL));

  num_open_fds = nfds = NUM;
  pfds = calloc(nfds, sizeof(struct pollfd));
  if (pfds == NULL) errExit("malloc");

  for (i=0;i<NUM;i++){           
    tt=(unsigned char)rand()%9;
    dprintf(STDOUT_FILENO,"child %d life time is %X\n",i,tt);
           
    if (pipe(pipefd[i]) == -1) errExit("pipe");
    pfds[i].fd = pipefd[i][0];
    pfds[i].events = POLLIN;
    if ((cpid[i] = fork()) == -1) errExit("fork");

    if (cpid[i] == 0) {    
       close(pipefd[i][0]);
       for (int j=0; j<i; j++){  
           close(pipefd[j][0]);
           close(pipefd[j][1]);
       }
       write(pipefd[i][1], argv[1], strlen(argv[1]));
       write(pipefd[i][1], &i, 1);
       write(pipefd[i][1], &tt, 1);
       sleep(tt);
       close(pipefd[i][1]);
       _exit(EXIT_SUCCESS);
    }  
  }

  for (int j=0; j<i; j++) close(pipefd[j][1]);

  dprintf(STDOUT_FILENO,"Opened %d pipes, waiting...\n",num_open_fds);

  while (num_open_fds > 0) {

    do{
      dprintf(STDOUT_FILENO,"\ntry poll:\n");
      for (i = 0; i < NUM; i++) pfds[i].revents=0;
      ready = poll(pfds, nfds, -1);
      if(ready == -1)
         switch (errno) {
           case EINTR: dprintf(STDOUT_FILENO,"\nPoll interrupted, repeat.\n"); 
                       continue;
           default: errExit("poll");
         }
    } while (ready <= 0);

    for (i = 0; i < NUM; i++) {
       if (pfds[i].revents != 0) {
          dprintf(STDOUT_FILENO,"  fd=%d; events: %7s%8s%9s%8s%8s  ", pfds[i].fd,
                  (pfds[i].revents & POLLIN)  ? "POLLIN "  : "",
                  (pfds[i].revents & POLLHUP) ? "POLLHUP " : "",
                  (pfds[i].revents & POLLNVAL) ? "POLLNVAL " : "",
                  (pfds[i].revents & POLLPRI) ? "POLLPRI " : "",
                  (pfds[i].revents & POLLERR) ? "POLLERR " : "");
          if (pfds[i].revents & POLLIN) {

             do {
                rr=read(pfds[i].fd, &buf, 1);
                if (rr < 0)
                   switch (errno) {
                     case EINTR: dprintf(STDOUT_FILENO,"\nRead interrupted, repeat.\n"); 
                                 continue;
                     default: errExit("read");
                   }
               if(rr == 0 ) 
                   dprintf(STDOUT_FILENO,"\n");
               else
                   dprintf(STDOUT_FILENO,"[%2X]",buf);
             } while (rr > 0);

          } 
          else 
          if ((pfds[i].revents & (POLLHUP | ~POLLIN))) {
             dprintf(STDOUT_FILENO,"Closing [%d], pipefd %d, pfds.fd %d\n",i,pipefd[i][0],pfds[i].fd);
             if (close(pfds[i].fd) < 0 ) errExit("close pfds");
             pfds[i].fd = -1;
             pfds[i].events=0;
             num_open_fds--;
             dprintf(STDOUT_FILENO,"Still opened fds %d\n",num_open_fds);
          }
       }
    }
  }
printf("Niggers");
while (1) pause;
  return EXIT_SUCCESS;
}