Dereferencing NULL pointer 'head' ,'tail

Question

I made a snake program with Linked List, the program is working but I have some warning, I wonder if I did something wrong or its just something to ignore.The program itself working without any bugs.

I

//Thats what I send from main

SNAKE* snake = (SNAKE*)malloc(sizeof(SNAKE));





//Thats the function
void initialSnaKE(SNAKE* snake){
    NODE* tail = (NODE*)(malloc(sizeof(NODE)));
    NODE* head = (NODE*)(malloc(sizeof(NODE)));
    head->prev = NULL;
    tail->prev = head;
    head->next = tail;
    tail->next = NULL;
    head->x = ROWS / 2;
    head->y = COLS / 2;
    snake->head = head;
    snake->tail = tail;
}

Answer 1

There are chances that malloc may fail, that is what compiler is complaining. You have to have proper NULL checks before dereferencing the pointers.

void initialSnaKE(SNAKE* snake){

    if (!snake) return; //invalid input

    NODE* tail = (NODE*)(malloc(sizeof(NODE)));
    if (!tail) return; //allocation failed.

    NODE* head = (NODE*)(malloc(sizeof(NODE)));
    if (!head) {
       free(tail);
       return;
     }


    head->prev = NULL;
    tail->prev = head;
    head->next = tail;
    tail->next = NULL;
    head->x = ROWS / 2;
    head->y = COLS / 2;
    snake->head = head;
    snake->tail = tail;
}