Remember that malloc is a least-common-denominator interface. It needs to work everywhere. In a lot of places, it could be hard to justify the complexity. Anyw

Remember that malloc is a least-common-denominator interface. It needs to work everywhere. In a lot of places, it could be hard to justify the complexity. Anyway, on glibc systems, you can use malloc_usable_size. On Windows systems (Windows gets the heap very right), you can use the HeapSize function.