Function memccpy 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn memccpy(
    s1: *mut c_void,
    s2: *const c_void,
    c: c_int,
    n: size_t,
) -> *mut c_void

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/memccpy.html.

Safety

The caller must ensure that:

• n is not longer than the memory area pointed to by s1, and
• n is not longer than the memory area pointed to by s2.