Re: Joy of this, Joy of that

On 27/11/2024 18:32, Richard Kettlewell wrote:

You can absolutely write an allocator that does that if you
want. You’ll
pay for it in performance and memory usage, but it might well be
worthwhile in a given application.
However, it doesn’t fully solve the problem. Suppose the sequence of
operations (with lots going on between) happens to look like this:
    int *p = malloc(xxx);
    // ...
    free(p);
    // ...
    int *q = malloc(yyy);
    // ...
    free(p);             // double free of p
    // ...
    *q = 1;
If p!=q then a tracking allocator like you envisage would spot the
error. But if it happens that p=q (which is entirely possible) then the
tracking allocator won’t notice the problem. The program will start to
misbehave seriously when the it access the (now freed) memory pointed to
be q.

 
Ah. But I cant see how to prevent that unless you give every block a
UID as well.
Which isn't a huge overhead.