OK, thanks, I will try out that approach.

Alan

On 22/05/2015 16:17, "Daniel Stenberg" <daniel_at_haxx.se> wrote:

>On Thu, 21 May 2015, Alan Cronin (alcronin) wrote:
>
>> For the first approach of creating a custom allocator have you heard of
>> people taking this approach before to zero memory. In this case it
>>would be
>> tested using in house tools and up to the creators of the allocator to
>> ensure that it works. My only concern with this approach is in the free
>> callback that cURL uses to deallocate memory. All that is supplied is
>>an
>> address and not a size, so to zero the data before freeing would need
>>either
>> a modification of the callback or a structure to be created around the
>>data
>> which stores the size, which can lead to issues in itself.
>
>What issues would that lead to? As long as the function you use to
>allocate
>memory allocate memory on aligned addresses you should be fine on most
>architectures I would think. I've not done a custom allocator for this
>particular purpose but I've done similar operations many times in the
>past.
>
>Such a custom allocator would need to store the size of the newly
>allocated
>block so that it later can figure out how much to clear. Something like
>this
>_untested_ pseudo code:
>
>struct memory {
> size_t size;
>};
>
>void *malloc_replacement(size_t size)
>{
> struct memory *mem = malloc(sizeof(struct memory) + size)
> if(mem) {
> mem->size = size;
> return mem+sizeof(struct memory);
> }
>}
>
>void free_replacement(void *ptr)
>{
> struct memory *mem = ptr - sizeof(struct memory);
> memset(ptr, 0, mem->size); /* clear memory area */
> free(mem);
>}
>
>--
>
> / daniel.haxx.se
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Received on 2015-05-22