Function mmap_file 

pub unsafe fn mmap_file(
    addr: *mut u8,
    len: usize,
    prot: u32,
    flags: u32,
    fd: &impl AsRawFd,
    off: usize,
) -> Result<Mmap>

Creates a file-backed memory mapping.

Safety

If the map is shared, then the application must be careful about potential undefined behavior if the underlying file changes, in or out of process.