Function nix::sys::mman::mmap

pub unsafe fn mmap(
    addr: *mut c_void, 
    length: size_t, 
    prot: ProtFlags, 
    flags: MapFlags, 
    fd: RawFd, 
    offset: off_t
) -> Result<*mut c_void>

Calls to mmap are inherently unsafe, so they must be made in an unsafe block. Typically a higher-level abstraction will hide the unsafe interactions with the mmap'd region.