2D process control

process_tree.c

#include <errno.h>
#include <unistd.h>
#include <sys/types.h>		/* used by pid_t */
#include <sys/wait.h>
#include <signal.h>

#include <stdio.h>
#include <stdlib.h>

#define TRUE 1
#define FALSE 0
/* How many times program returns to the parent to run the new branch of
   processes
*/
#define YDEPTH 2

void spawn(int n, int np, pid_t ppid, int y);

/* Main Procedure ****************************************************/
int
main (void) {
  int tree[YDEPTH], rv;
  pid_t ppid;
  
  // Set the process tree branches
  tree[0] = tree[1] = 3;

  // Top parent pid (host process)
  ppid = getpid();

  // Fork all child processes
  for (int depth = 0; depth < YDEPTH; ++depth) {
    printf ("PARENT %d: Spawinng a new branch with depth %i\n", getpid(), tree[depth]);
    spawn(tree[depth], tree[depth], ppid, depth);
    printf("Check back to parrent\n");
  }

  printf("Parent is free now\n");
  // Wait the top processes
  for (int index = 0; index < YDEPTH; ++index) {
    wait(&rv);
    printf("Parent process get RV %i\n", WEXITSTATUS(rv));
  }
  
  // Standard exit
  printf("*DONE*\n");
  return EXIT_SUCCESS;
}

/* Spawn procedure will fork n children processes */
// TODO: Add semephores
void
spawn(int n, int np, pid_t ppid, int y) {
  // pid_t chlid_pid;
  pid_t pid;
  int rv = -1;
  
  if (np) {
    switch (pid = fork()) {
    case -1:		        /* FORK RETURN AN ERROR (see `man 2 fork`, ERRORS section) */
      perror("Fork failed!\n");	/* something went wrong */
      exit(EXIT_FAILURE);       /* parent exits */
	
    case 0:			/* PID RETURNED IN THE CHILD */
      printf("> Z CHILD %d: My parent's PID = %d\n", getpid(), getppid());
      spawn (n, np - 1, ppid, y);
      // Run process job
      int jobs_done = 2;
      while (jobs_done) {
	sleep(1);
	printf("%i.%i> Hello, my pid is %i, and my parent's is %i\n",
	       np, y, getpid(), getppid());
	--jobs_done;
      }
      printf("%d IS DONE (%i/%i/%i)\n", getpid(), y, n, np);
      if (np != 1) {
        printf("Parent %i waiting for child to exit\n", getpid());
	wait(&rv);
	sleep(0 );
	printf("RV = %i\n", WEXITSTATUS(rv));
      }
      printf("%d EXIT\n", getpid());
      exit(10);

    default:
      printf ("> SKIP IN %i: My parent's PID = %i; My childrens pid = %i\n",
	      getpid(), getppid(), pid);
    }
  }
  
  printf("\n%d GET SOMETHING TO DO\n", getpid());
}