Lista dwukierunkowa - pełna

#include <stdio.h>
#include <stdlib.h>
typedef struct Bron Bron;
struct Bron{
    int numer_broni;
    Bron *prev;
    Bron *next;
};

Bron* dodaj_pierwszy(Bron *head, Bron* nowy){

    if(head == NULL){
        nowy->next = NULL;
        nowy->prev = NULL;
        head = nowy;
    }else{
        nowy->prev = NULL;
        nowy->next = head;
        head->prev = nowy;
        head = nowy;
    }
    return head;

}

Bron* dodaj_ostatni(Bron *head, Bron *nowy){
   Bron *first = head;
    while(first->next != NULL){
        first = first->next;
    }

    first->next = nowy;
    nowy->prev = first;
    nowy->next = NULL;

    return head;

}

Bron* dodaj_na_N(Bron *head, Bron *nowy, int poz){
    Bron *first = head;
    int i = 2;
    while(first->next != NULL){
        if(i == poz){
            nowy->next = first->next;
            first->next->prev = nowy;
            nowy->prev = first;
            first->next = nowy;
        }
        i++;
        first = first->next;

    }
    if(poz >= i){
        head = dodaj_ostatni(head, nowy);
    }
    return head;
}

Bron* usuwanie(Bron *head, int poz){
    Bron *first = head;
    if(poz == 0){
        first->next->prev = NULL;
        head = first->next;

    }else if(poz == 1){
        while(first->next != NULL){
            first = first->next;
        }
        first->prev->next = NULL;
    }
    free(first);
    return head;
}

Bron* dodaj_nowy(Bron *head, Bron* nowy, int poz){
    if(poz == 1){
       head = dodaj_pierwszy(head, nowy);
    }else{
        head = dodaj_na_N(head, nowy, poz);
    }
   return head;
}
int main() {
    Bron *pierwsza = (Bron *) malloc(sizeof(Bron));
    pierwsza->numer_broni = 123;
    pierwsza->next = NULL;
    pierwsza->prev = NULL;
    Bron *nowa = (Bron *) malloc(sizeof(Bron));
    Bron *nowa1 = (Bron *) malloc(sizeof(Bron));
    Bron *nowa2 = (Bron *) malloc(sizeof(Bron));
    Bron *nowa3 = (Bron *) malloc(sizeof(Bron));
    nowa->numer_broni = 321;
    nowa1->numer_broni = 56;
    nowa2->numer_broni = 90;
    nowa3->numer_broni = 5;
    pierwsza = dodaj_pierwszy(pierwsza, nowa);
    pierwsza = dodaj_ostatni(pierwsza, nowa1);
    pierwsza = dodaj_ostatni(pierwsza, nowa3);
    //pierwsza = usuwanie(pierwsza, 0);
    pierwsza = dodaj_nowy(pierwsza, nowa2, 5);


    Bron* first = pierwsza;
    if(first != NULL){
        while(first != NULL){
            printf("Numer broni: %d \n", first->numer_broni);
            first = first->next;
        }
    }
    return 0;
}