Function sallocx 

pub unsafe extern "C" fn sallocx(
    ptr: *const c_void,
    flags: c_int,
) -> size_t

Returns the real size of the previously-allocated memory region referenced by ptr.

The value may be larger than the size requested on allocation.

Safety

The behavior is undefined if:

• ptr does not match a pointer earlier returned by the memory allocation functions of this crate, or
• the memory region referenced by ptr has been deallocated.