Thread: Memory management woes

I'm trying to make a linked list, but my head seems to be staying eternally null. I defined a node struct and my head

Code:

typedef struct node_s
{
   int id;
   data_t data;
   struct node_s *next;
} node_t;

node_t *headNode = NULL;

I created an insert function that should allow for inserting id and data into any list

Code:

void insert(int id, data_t data, node_t **head)
{
   node_t *cur = NULL;

   nodeDup(cur, *head);
  //find where to insert

  if(cur == NULL)
  {
     *head = (node_t *)malloc(sizeof(node_t));
     //assign values
  }
}

void nodeDup(node_t *v1, node_t *v2)
{
  if(v2 == NULL)
    return;

  v1 = (node_t *)malloc(sizeof(node_t));

  v1->id = v2->id;
  //etc
}

int main()
{
...
insert(1, data, &headNode);
insert(2, data, &headNode);
...
}

cur is always null, even in successive calls to insert. Shouldn't "*head = (node_t *)malloc(sizeof(node_t));" be causing headNode to no longer be null?

Ah, ok. Thanks. So my dup function was wrong. I changed it to return a pointer and assigned cur to it and it worked. I guess I could have also made v1 a double pointer and that would have worked too, right?