用valgrind修复内存泄漏

Question

i built a linked list library and i wrote a clear function which go through the list and free all the memory associated with list. like this:

/creating the list
list *myList = (list*) calloc(1, sizeof(list));

//lets try to add a node to the list
list_add_at (NULL, 0, (int*)100);
list_add_at (myList, 0, (int*)100);
list_add_at (myList, 1, (int*)200);
list_add_at (myList, 2, (int*)300);
list_add_at (myList, 3, (int*)400);
list_add_at (myList, 4, (int*)600);
list_add_at (myList, 5, (int*)800);

list_clear(myList);

and then when i run the valgrind, it will say that "indirectly lost: 120 bytes in 5 blocks" and this is the number of nodes i added to the list. my question is how i can free these memory locations i used ?

Thanks

Answer 1

According to valgrind documentation ,

"indirectly lost" means your program is leaking memory in a pointer-based structure.

In other words, this is an indication that your linked list node has another pointer that you have set to a result of malloc , and you have forgotten to de-allocate that memory.

The fix would be to add free for the pointer inside the linked list node:

while ( temp != NULL ){
        list->head = temp->next;
        free(temp->allocated_ptr); // <<= Free the memory attached to the node
        free(temp);
        temp = list->head;
}