Chocolate brownie

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

#define MAX_NAZIV (20 + 1)
#define MAX_PROIZVODJAC (12 + 1)

typedef struct brownie_st{
    char naziv[MAX_NAZIV];
    unsigned int kolicina;
    double cena;
    char proizvodjac[MAX_PROIZVODJAC];
    struct brownie_st *right;
    struct brownie_st *left;
}BROWNIE;

void tree_init(BROWNIE**);
void delete_tree(BROWNIE**);
BROWNIE* make_brownie(char*,unsigned int,double,char*);
void add_to_tree(BROWNIE**,BROWNIE*);

FILE* safe_open(char*,char*);
void load(FILE*,BROWNIE**);
void save(FILE*,BROWNIE*,char*,double*,BROWNIE**);

int main(int argc,char** argv){
    if(argc != 4){
        printf("nepravilan poziv programa.");
        return EXIT_FAILURE;
    }else{
        BROWNIE *koren,
                *max    = NULL;
        FILE    *file = safe_open(argv[1],"r");
        double ukupno = 0;
        tree_init(&koren);
        load(file,&koren);
        fclose(file);
        file = safe_open(argv[2],"w");
        save(file,koren,argv[3],&ukupno,&max);
        fprintf(file,"\nUkupna cena namirnica je %.3lf.",ukupno);
        if(max != NULL){
            fprintf(file,"\nNamirnica sa najvecom gramazom proizvodjaca %s je: %s",argv[3],max->naziv);
        }
        fclose(file);
        delete_tree(&koren);
        return EXIT_SUCCESS;
    }
}

void tree_init(BROWNIE** koren){
    *koren = NULL;
    return;
}

void delete_tree(BROWNIE** koren){
    if(*koren != NULL){
        delete_tree(&(*koren)->left);
        delete_tree(&(*koren)->right);
        free(*koren);
    }
    return;
}

BROWNIE* make_brownie(char* naziv,unsigned int kolicina,double cena,char* proizvodjac){
    BROWNIE* new = (BROWNIE*)malloc(sizeof(BROWNIE));
    if(new == NULL){
        printf("nije moguce zauzeti memoriju.");
        exit(EXIT_FAILURE);
    }
    strcpy(new->naziv,naziv);
    strcpy(new->proizvodjac,proizvodjac);
    new->kolicina = kolicina;
    new->cena = cena;
    new->left = NULL;
    new->right = NULL;
    return new;
}
//s1<s2=<=-1
void add_to_tree(BROWNIE** koren,BROWNIE* new){
    if(*koren == NULL){
        *koren = new;
    }else{
        if(strcmp((*koren)->naziv,new->proizvodjac) > 0){
            add_to_tree(&(*koren)->right,new);
        }else{
            add_to_tree(&(*koren)->left,new);
        }
    }
    return;
}

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

void load(FILE* f,BROWNIE** koren){
    char naziv[MAX_NAZIV],
         proizvodac[MAX_PROIZVODJAC];
    unsigned int kolicina;
    double cena;
    while(fscanf(f,"%s %u %lf %s",
                                naziv,
                                &kolicina,
                                &cena,
                                proizvodac) != EOF){
        add_to_tree(koren,make_brownie(naziv,kolicina,cena,proizvodac));
    }
    return;
}

void save(FILE* f,BROWNIE* koren,char* param,double* ukupno,BROWNIE** max){
    if(koren != NULL){
        save(f,koren->left,param,ukupno,max);
        fprintf(f,"%s %u %.3lf\n",koren->naziv,koren->kolicina,koren->cena*(koren->kolicina/100.));
        *ukupno += koren->cena*(koren->kolicina/100.);
        if(strcmp(koren->proizvodjac,param) == 0){
            if(*max == NULL){
                    *max = koren;
            }else{
                if((*max)->kolicina < koren->kolicina){
                    *max = koren;
                }
            }
        }
        save(f,koren->right,param,ukupno,max);
    }
    return;
}