region/
util.rs

1use crate::{page, Error, Result};
2
3/// Validates & rounds an address-size pair to their respective page boundary.
4pub fn round_to_page_boundaries<T>(address: *const T, size: usize) -> Result<(*const T, usize)> {
5  if size == 0 {
6    return Err(Error::InvalidParameter("size"));
7  }
8
9  let size = (address as usize % page::size()).saturating_add(size);
10  let size = page::ceil(size as *const T) as usize;
11  Ok((page::floor(address), size))
12}
13
14#[cfg(test)]
15mod tests {
16  use super::*;
17
18  #[test]
19  fn round_to_page_boundaries_works() -> Result<()> {
20    let pz = page::size();
21    let values = &[
22      ((1, pz), (0, pz * 2)),
23      ((0, pz - 1), (0, pz)),
24      ((0, pz + 1), (0, pz * 2)),
25      ((pz - 1, 1), (0, pz)),
26      ((pz + 1, pz), (pz, pz * 2)),
27      ((pz, pz), (pz, pz)),
28    ];
29
30    for ((before_address, before_size), (after_address, after_size)) in values {
31      let (address, size) = round_to_page_boundaries(*before_address as *const (), *before_size)?;
32      assert_eq!((address, size), (*after_address as *const (), *after_size));
33    }
34    Ok(())
35  }
36}