how can I use `curr_user` ?
int create_user(const char *name, User **user_ptr_add) {

    User *curr_user = *user_ptr_add;

    if (strlen(name) > 29) {
        return 2;
    }
    while (curr_user->next != NULL) {
        if (strcmp(name, curr_user->name) == 0) {
            return 1;
        }
        curr_user = curr_user->next;
}
    User *new_user = malloc(sizeof(User));

    strncpy(new_user->name, name, strlen(name));
    new_user->name[strlen(name)] = '\0';
    new_user->profile_pic[0] = '\0';
    new_user->first_post = NULL;
    memset(new_user->friends, '\0', sizeof(new_user->friends));
    new_user->next = NULL;

    *user_ptr_add = new_user;
    return 0;
}