Linked list with header (first, last, count)

linked_list.c

#include <stdio.h>

typedef struct node {
    int val;
    struct node *next;
} node_t;

typedef struct head {
    node_t *first;
    node_t *last;
    int count;
} head_t;

//Funções
void start_list(head_t *head_list);
int show_list(head_t *head_list);
void add_node(head_t *linked_list, int value);
void count_elements(head_t *head_list);
void remove_last_node(head_t *head_list);


int main(void) {

    //Alocando o cabeçalho
    head_t *head_list = (head_t*) malloc(sizeof(head_t));

    start_list(head_list);
    printf("Contagem de lista %d\n", head_list->count);
    show_list(head_list);
    add_node(head_list, 5);
    add_node(head_list, 55);
    add_node(head_list, 1);
    show_list(head_list);
    count_elements(head_list);
    remove_last_node(head_list);
    show_list(head_list);

    return 0;
}


void start_list(head_t *head_list) {
    head_list->first = NULL;
    head_list->last = NULL;
    head_list->count = 0;
}

int show_list(head_t *head_list) {
    node_t *current = malloc(sizeof(node_t));
    current = head_list->first;
    int i = 0;

    if (head_list->first == NULL) {
        printf("Lista vazia!\n");
        return 1;
    }
    while(current->next != NULL) {
        printf("Node[%d] = %d\n", i, current->val);
        current = current->next;
        i++;
    }

    if (current->next == NULL) {
        printf("Node[%d] = %d\n", i, current->val);
    }

    return 0;
}

void add_node(head_t *linked_list, int value) {
  node_t *node = malloc(sizeof(node_t));
  node_t *new_node = malloc(sizeof(node_t));

  int node_address = 0;

  if (node == NULL) {
    printf("Out of memory, exiting.\n");
  }

  //A lista está vazia? Se sim, adicionamos o primeiro nó.
  if (linked_list->first == NULL) {
    linked_list->first = node;
    node->next = NULL;
    node->val = value;
    linked_list->count++;
    linked_list->last = node;
  } else {
    //Se a lista não estiver vazia, o nó será o primeiro da lista.
    node = linked_list->first;

    while(node->next != NULL) {
      node = node->next;
    }
    node->next = new_node;
    new_node->next = NULL;
    new_node->val = value;
    linked_list->count++;
    linked_list->last = new_node;
  }

}

void count_elements(head_t *head_list) {
    printf("Elementos na lista = %d\n", head_list->count);
}

void remove_last_node(head_t *head_list) {
    node_t *current = malloc(sizeof(node_t));
    node_t *last_node = malloc(sizeof(node_t));
    current = head_list->first;
    last_node = head_list->last;

    while(current->next->next != NULL) {
        current = current->next;
    }

    current->next = NULL;
    free(last_node);
}