Просечна цена горива

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_GRAD   (2 + 1)
#define MAX_GORIVO (10 + 1)

typedef struct gorivo_st{
    char grad[MAX_GRAD];
    char gorivo[MAX_GORIVO];
    float cena;
    struct gorivo_st *sl;
}GORIVO;

void list_init(GORIVO**);
void delete_list(GORIVO**);
GORIVO* make_gorivo(char*,char*,float);
void add_to_list(GORIVO**,GORIVO*);

FILE* safe_open(char*,char*);
void load(FILE*,GORIVO**);
void save(FILE*,GORIVO*,char*);

int main(int argc,char** argv){
    if(argc != 4){
        printf("nepravilan poziv programa.");
        return EXIT_FAILURE;
    }else{
        GORIVO *glava;
        FILE   *file = safe_open(argv[2],"r");
        list_init(&glava);
        load(file,&glava);
        fclose(file);
        file = safe_open(argv[3],"w");
        save(file,glava,argv[1]);
        fclose(file);
        delete_list(&glava);
        return EXIT_SUCCESS;
    }
}

void list_init(GORIVO** glava){
    *glava = NULL;
    return;
}

void delete_list(GORIVO** glava){
    GORIVO* t = *glava;
    while(*glava != NULL){
        t = *glava;
        *glava = (*glava)->sl;
        free(t);
    }
    return;
}

GORIVO* make_gorivo(char* grad,char* gorivo,float cena){
    GORIVO* new = (GORIVO*)malloc(sizeof(GORIVO));
    if(new == NULL){
        printf("Nije moguce zauzeti memoriju.");
        exit(EXIT_FAILURE);
    }
    strcpy(new->grad,grad);
    strcpy(new->gorivo,gorivo);
    new->cena = cena;
    new->sl = NULL;
    return new;
}

void add_to_list(GORIVO** glava,GORIVO* new){
    if(*glava == NULL){
        *glava = new;
    }else{
        GORIVO* t = *glava;
        while(t->sl != NULL){
            t = t->sl;
        }
        t->sl = new;
    }
    return;
}

FILE* safe_open(char* name,char* mode){
    FILE* f = fopen(name,mode);
    if(f == NULL){
        printf("Nije moguce otvoriti fajl %s.",name);
        exit(EXIT_FAILURE);
    }
    return f;
}

void load(FILE* f,GORIVO** glava){
    char grad[MAX_GRAD],
         gorivo[MAX_GORIVO];
    float cena;
    while(fscanf(f,"%s %s %f",
                            grad,
                            gorivo,
                            &cena) != EOF){
        add_to_list(glava,make_gorivo(grad,gorivo,cena));
    }
    return;
}

void save(FILE* f,GORIVO* glava,char* param){
    GORIVO* t = glava;
    float prosek = 0;
    int count = 0;
    while(t != NULL){
        fprintf(f,"%6.2f %s %s\n",t->cena,t->grad,t->gorivo);
        if(strcmp(t->gorivo,param) == 0){
            prosek += (*t).cena;
            count++;
        }
        t = t->sl;
    }
    if(count != 0){
        fprintf(f,"\nAVG = %.2f",prosek/count);
    }else{
        fprintf(f,"\nNOT FOUND!");
    }
    return;
}