Invalid reads, writes and frees

Question

I got a lot of write, read and free errors. I don't know where is mistake. If someone could help me out with this I'd be grateful. Here is log from valgrind:
http://pastebin.com/TR4Ts73Y

void deleteElement(element* node) {
element* child;
if (node == NULL)
    return;

free(node->name);

if (node->text != NULL)
    free(node->text);

child = node->firstChild;
while(child != NULL)
{
    deleteElement(child);
    child = child->nextSibling;
}

free(node);
}

If you need more functions feel free to ask for.

Try to share a full program, preferably reduced to the core of the problem. — Bryan Olivier, Mar 30 '13 at 09:12
I'm not sure, but I think this will be kinda helpful: http://stackoverflow.com/questions/5011990/c-programming-linked-lists-delete-node-at-position-n — M. Suleiman, Mar 30 '13 at 09:12

score 3 · Accepted Answer · answered Mar 30 '13 at 09:16

3

The error in the code in the question is here:

while(child != NULL)
{
    deleteElement(child); // this calls free on child
    child = child->nextSibling; // OOPS, child has been freed
}

Here you destroy child and then immediately try to use it again. You need an extra variable.

while(child != NULL)
{
    element* nodeToDelete = child;
    child = child->nextSibling;
    deleteElement(nodeToDelete);
}

There may be other errors in your complete program, but that's the obvious one that can be detected in the code excerpt that you posted.

answered Mar 30 '13 at 09:16

David Heffernan

601,492
42
1,072
1,490

Thanks! Is it somehow possible to send you the rest of the code? I can't share it publicly so... – Mar 30 '13 at 09:26
I've put there other functions – Mar 30 '13 at 10:26
If you can't post them here, then we can't help. I rolled back the question. I think I answered the question that you asked. If you have further problems, make that further questions. – David Heffernan Mar 30 '13 at 10:36

Invalid reads, writes and frees

1 Answers1