Function mmap 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn mmap(
    addr: *mut c_void,
    len: size_t,
    prot: c_int,
    flags: c_int,
    fildes: c_int,
    off: off_t,
) -> *mut c_void

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