osx man page for malloc_size

MALLOC_SIZE(3)						   BSD Library Functions Manual 					    MALLOC_SIZE(3)

NAME
     malloc_good_size, malloc_size -- memory allocation information

SYNOPSIS
     #include <malloc/malloc.h>

     size_t
     malloc_good_size(size_t size);

     size_t
     malloc_size(const void *ptr);

DESCRIPTION
     The malloc_size() function returns the size of the memory block that backs the allocation pointed to by ptr.  The memory block size is always
     at least as large as the allocation it backs, and may be larger.

     The malloc_good_size() function rounds size up to a value that the allocator implementation can allocate without adding any padding; it then
     returns that rounded-up value.

SEE ALSO
     malloc(3)

BSD
								   May 23, 2006 							       BSD