zombifier.cpp

///////////////////////////
// zombifier.cpp
//
// assignment: hw2
// author: Gianna Fusaro
// date: 03/07/15
// class: CS149
// instructor: Dr. Gomez
///////////////////////////

#include <unistd.h>
#include <iostream>
#include <csignal>
using namespace std;

void SummonTheReaper() {
  cout << "\n                 ...\n";
  cout << "               ;::::;\n";
  cout << "             ;::::; :;\n";
  cout << "           ;:::::'   :;\n";
  cout << "          ;:::::;     ;.\n";
  cout << "         ,:::::'       ;           OOO\\\n";
  cout << "         ::::::;       ;          OOOOO\\\n";
  cout << "         ;:::::;       ;         OOOOOOOO\n";
  cout << "        ,;::::::;     ;'         / OOOOOOO\n";
  cout << "      ;:::::::::`. ,,,;.        /  / DOOOOOO\n";
  cout << "    .';:::::::::::::::::;,     /  /     DOOOO\n";
  cout << "   ,::::::;::::::;;;;::::;,   /  /        DOOO\n";
  cout << "  ;`::::::`'::::::;;;::::: ,#/  /          DOOO\n";
  cout << "  :`:::::::`;::::::;;::: ;::#  /            DOOO\n";
  cout << "  ::`:::::::`;:::::::: ;::::# /              DOO\n";
  cout << "  `:`:::::::`;:::::: ;::::::#/               DOO\n";
  cout << "   :::`:::::::`;; ;:::::::::##                OO\n";
  cout << "   ::::`:::::::`;::::::::;:::#                OO\n";
  cout << "   `:::::`::::::::::::;'`:;::#                O\n";
  cout << "    `:::::`::::::::;' /  / `:#\n";
  cout << "     ::::::`:::::;'  /  /   `#\n";

  while(true) {
    pid_t pid = wait(NULL);
    if(pid == -1) {
      cout << "\nAll zombies have been slaughtered!\n";
      cout << "\nCheck your running processes -- I'll just hang out here until you kill me by pressing enter.\n";
      cin.ignore();
      exit(0);
    } else {
      cout << "...Reaping zombie process " << pid << "\n";
    }
  }
}

void signalHandler(int signal_number) {
  // Use a switch statement so we can conveniently add more signal handlers in the future
  switch(signal_number) {
    case 20:
      cout << "\nInterrupt signal 20) SIGCHLD received.\n";
      SummonTheReaper();
      break;
  }
}

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

  // Ensure the arguments are valid
  try {
    if(argc != 3) {
      cout << "Incorrect number of arguments!\n"; throw(0);
    } else if(strcmp(argv[1],"-n") != 0) {
      cout << "Unknown option " << argv[1] << "\n"; throw(0);
    } else if(atoi(argv[2]) < 1) {
      cout << "Must specify desired number of zombies!\n"; throw(0);
    }
  } catch(...) {
    cout << "    Usage: zombifier -n <number of zombies>\n";
    exit(0);
  }

  // Declare variables
  int i;
  int n = atoi(argv[2]);
  pid_t pid;

  // Create requested number of zombie processes
  cout << "Raising " << n << " zombies from the dead!\n\n";

  for (i = 0; i < n; i++)  {
    pid = fork();
    if (pid > 0) {
      cout << "...Creating zombie process " << pid << "\n";
      sleep(1);
    } else {
      // Just kill the children immediately
      exit(0);
    }
  }

  cout << "\nYour zombie horde is ready! Check your running processes.\n";
  cout << "                    .....   \n";
  cout << "                   C C  /   \n";
  cout << "                  /<   /    \n";
  cout << "   ___ __________/_#__=o    \n";
  cout << "  /(- /(\\_\\________   \\     \n";
  cout << "  \\ ) \\ )_      \\o     \\    \n";
  cout << "  /|\\ /|\\       |'     |    \n";
  cout << "                |     _|    \n";
  cout << "                /o   __\\    \n";
  cout << "               / '     |    \n";
  cout << "              / /      |    \n";
  cout << "             /_/\\______|    \n";
  cout << "            (   _(    <     \n";
  cout << "             \\    \\    \\    \n";
  cout << "              \\    \\    |   \n";
  cout << "               \\____\\____\\  \n";
  cout << "               ____\\_\\__\\_\\ \n";
  cout << "             /`   /`     o\\ \n";
  cout << "             |___ |_______|\n";

  // Initalize the signal handler AFTER we create the zombies
  signal(SIGCHLD, signalHandler);

  // Tell the user how to kill the zombie processes
  cout << "\nSend me a SIGCHLD signal or press enter to summon the grim reaper.\n";
  cin.get();
  SummonTheReaper();
}