// The Great Fork!
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <assert.h>
#include <errno.h>
#include <sys/wait.h>
#define sz (1<<(22-3))
#define dc 4
#define pc 3
void pwho(int r, int v){printf("I am %d from %d at %d: %d\n",
   (int)getpid(), (int)getppid(), r, v);}

int main(){int * big = malloc (sz<<3); int v=pc;
pid_t who[pc]; pwho(1, -1);
srandom(42);
{int y=dc; while(y--) {int u = random()&(sz-1); big[u] = u;}}
while(v--) {pid_t w = fork(); pwho(2, v);
if(w<0) {printf("w = %d\n", (int)w);
  if(w==-1) {if(errno == EAGAIN) printf("EAGAIN!!\n");
  else printf("errno=%d; EAGAIN=%d EDEADLK=%d\n", errno, EAGAIN, EDEADLK);}}
  assert(w>=0);
  if(w) who[v]=w; else goto child;}
assert(v==-1);
printf("%d launched\n", pc);
{int y=pc; while(y--) {int stat; pid_t k = wait(&stat);
  {int z=pc; while(z--) if(k==who[z]) {who[z]=0; goto good;}
  exit(printf("Whozzat?\n")); good: 
  if (WIFEXITED(stat)) printf("%d quit\n", WEXITSTATUS(stat));
  else exit(printf("Bang\n"));}}
exit(printf("All's well\n"));}
child: srandom(42); // The children do this.
pwho(3, v);
printf("Hello\n");
{int y=dc; while(y--) {int u = random()&(sz-1);
   printf("x=%0d %p %d\n", u, big, *(big+u));
   if(u-big[u]) exit(printf("foul"));}}
printf("Good\n"); pwho(4, v);
exit(v);}