Function nix::sys::mman::mmap

pub 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.