#include <stdio.h>
#include <stdlib.h> //for malloc(3)
#include <unistd.h> //for mmap, brk, sbrk

struct node
{
  char data;
  long num;
  struct node* link;
};

struct node list_head;

/**
 * Place 'tmp' onto the rear of the list. 
 * 
 * Lame, linear implementation.
 */
void
insert(struct node* tmp)
{
  struct node *itr = NULL;

  itr = &list_head;
  while(NULL!=itr->link)
  {
    itr = itr->link;
  }
  //now itr points to the "last" node on the list.
  //update last->link to be tmp

  itr->link = tmp;

  //tmp->link should already be NULL (via create_node())

  return;
}

void 
print_list()
{
  struct node *itr = NULL;

  itr = &list_head;
  while(NULL!=itr)
  {
    if(itr->link)
    {
      fprintf(stdout,
	      "[%c,%ld,%p]->",
	      itr->data,
	      itr->num,
	      itr->link);
    }else{
      fprintf(stdout,
	      "[%c,%ld,%s]",
	      itr->data,
	      itr->num,
	      "/");
    }
    itr = itr->link;
  }
  fprintf(stdout, "\n");
  return;
}

void
create_node(long i)
{
  struct node *tmp = NULL;

  tmp = malloc(sizeof(struct node));
  if(NULL == tmp)
  {
    fprintf(stderr, "failed to allocated space for new node\n");
    abort();
  }

  tmp->data = 'M';
  tmp->num = i;
  tmp->link = NULL;

  insert(tmp);
  
  tmp = NULL; //not needed, but semantically clears the pointer

  return;
}


void
do_work()
{
  long i = 0;
  for(;;)
  {
    create_node(i);
    i++;
    print_list();
    sleep(1);
  }
}


/**
 * Create some number of linked list nodes. 
 */
int main(int argc,
	 char* argv[])
{

  /* 'list_head' has been created for us by the compiler and placed
   * into the .data section of the ELF. Let's initialize its values.
   * The rest of the members of the list will exist on the heap.
   */
  list_head.data = 'M';
  list_head.num = -1;
  list_head.link = NULL;

  fprintf(stdout,
	  "my pid = %d\n",
	  getpid());

  fprintf(stdout,
	  "size of struct node is %d\n",
	  sizeof(struct node));

  do_work();

  return 0;

}