pub unsafe fn munmap(addr: usize, len: size_t) -> Result<(), Errno>
Expand description
Unmap files or devices from memory.
§Example
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(
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 = unsafe { nc::write(1, addr + offset - pa_offset, length) };
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());