Function nc::munmap

pub fn munmap(addr: usize, len: size_t) -> Result<(), Errno>

Unmap files or devices from memory.

let path = "/etc/passwd";
let ret = nc::openat(nc::AT_FDCWD, path, nc::O_RDONLY, 0o644);
assert!(ret.is_ok());
let fd = ret.unwrap();

let mut sb = nc::stat_t::default();
let ret = nc::fstat(fd, &mut sb);
assert!(ret.is_ok());

let offset: usize = 0;
let length: usize = sb.st_size as usize - offset;
// Offset for mmap must be page aligned.
let pa_offset: usize = offset & !(nc::PAGE_SIZE - 1);
let map_length = length + offset - pa_offset;

let addr = nc::mmap(
    0, // 0 as NULL
    map_length,
    nc::PROT_READ,
    nc::MAP_PRIVATE,
    fd,
    pa_offset as nc::off_t,
);
assert!(addr.is_ok());
let addr = addr.unwrap();

let n_write = nc::write(1, addr + offset - pa_offset, length);
assert!(n_write.is_ok());
assert_eq!(n_write, Ok(length as nc::ssize_t));
assert!(nc::munmap(addr, map_length).is_ok());
assert!(nc::close(fd).is_ok());