Re: Proposed addition of malloc_size_np()


On Sat, 25 Mar 2006, Jason Evans wrote:

Ok, so what you are saying is that the function returns the size of the bucket (if any) that the memory was allocated from... But even though this function may return a larger value, the program is not allowed to use extra space, and it's only useful for further allocations of the same size?

I'm saying that malloc_size_np() returns the size of the allocation, to the best of the allocator's knowledge. If you malloc(17), and malloc_size_np() returns 32 for that allocation, then you can treat it as a 32-byte allocation. However, the malloc implementation could conceivably return any value >=17.

I wonder if the intuitive objection people are raising is actually with the name. Since malloc_size() is defined on at least one platform to return the requested size, maybe a name like malloc_allocated_size() (or something a bit more compact) would help avoid that confusion, and make it clear that the consumer is getting back a commitment and not a hint for future realloc(), etc.

Robert N M Watson
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