I am trying to add memory deallocations to old C code. I have a hash table of custom objects (HASHREC). After analysis of current code and reading other SO questions, I know that I need to provide three levels of deallocations. Fist - word member, next HASHREC*, and then HASHREC**.
My version of free_table() function frees mentioned objects. Unfortunately, Valgrind still complains that some bytes are lost.
I am not able to provide full code, it will be too long, but I am presenting how HASHREC **vocab_hash is filled inside inithashtable() and hashinsert(). Could you give me a suggestion how should I fix free_table()?
typedef struct hashrec {
char *word;
long long count;
struct hashrec *next;
} HASHREC;
HASHREC ** inithashtable() {
int i;
HASHREC **ht;
ht = (HASHREC **) malloc( sizeof(HASHREC *) * TSIZE );
for (i = 0; i < TSIZE; i++) ht[i] = (HASHREC *) NULL;
return ht;
}
void hashinsert(HASHREC **ht, char *w) {
HASHREC *htmp, *hprv;
unsigned int hval = HASHFN(w, TSIZE, SEED);
for (hprv = NULL, htmp = ht[hval]; htmp != NULL && scmp(htmp->word, w) != 0; hprv = htmp, htmp = htmp->next);
if (htmp == NULL) {
htmp = (HASHREC *) malloc( sizeof(HASHREC) ); //<-------- problematic allocation (Valgrind note)
htmp->word = (char *) malloc( strlen(w) + 1 );
strcpy(htmp->word, w);
htmp->next = NULL;
if ( hprv==NULL ) ht[hval] = htmp;
else hprv->next = htmp;
}
else {/* new records are not moved to front */
htmp->count++;
if (hprv != NULL) { /* move to front on access */
hprv->next = htmp->next;
htmp->next = ht[hval];
ht[hval] = htmp;
}
}
return;
}
void free_table(HASHREC **ht) {
int i;
HASHREC* current;
HASHREC* tmp;
for (i = 0; i < TSIZE; i++){
current = ht[i];
while(current != NULL) {
tmp = current;
current = current->next;
free(tmp->word);
}
free(ht[i]);
}
free(ht);
}
int main(int argc, char **argv) {
HASHREC **vocab_hash = inithashtable();
// ...
hashinsert(vocab_hash, w);
//....
free_table(vocab_hash);
return 0;
}