Function munmap

pub unsafe fn munmap(addr: *const c_void, len: usize) -> Result<(), i32> 

Available on crate feature dep_nc only.

Unmap files or devices from memory.

Examples

use std::{mem, ptr};

let path = "/etc/passwd";
let ret = unsafe { 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 = unsafe { 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 = unsafe {
    nc::mmap(
        ptr::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 stdout = 1;

// Create the "fat pointer".
let buf = unsafe {
    mem::transmute::<(usize, usize), &[u8]>((addr as usize + offset - pa_offset, length))
};
let n_write = unsafe { nc::write(stdout, buf) };
assert!(n_write.is_ok());
assert_eq!(n_write, Ok(length as nc::ssize_t));
let ret = unsafe { nc::munmap(addr, map_length) };
assert!(ret.is_ok());
let ret = unsafe { nc::close(fd) };
assert!(ret.is_ok());