bare_io/
util.rs

1#[cfg(feature = "nightly")]
2use core::mem::MaybeUninit;
3
4#[cfg(feature = "nightly")]
5use crate::{ErrorKind, Read, Write};
6
7#[cfg(feature = "nightly")]
8pub fn copy<R: ?Sized, W: ?Sized, const S: usize>(
9    reader: &mut R,
10    writer: &mut W,
11) -> crate::Result<u64>
12where
13    R: Read,
14    W: Write,
15{
16    let mut buf = MaybeUninit::<[u8; S]>::uninit();
17    // FIXME: #42788
18    //
19    //   - This creates a (mut) reference to a slice of
20    //     _uninitialized_ integers, which is **undefined behavior**
21    //
22    //   - Only the standard library gets to soundly "ignore" this,
23    //     based on its privileged knowledge of unstable rustc
24    //     internals;
25    unsafe {
26        reader.initializer().initialize(buf.assume_init_mut());
27    }
28
29    let mut written = 0;
30    loop {
31        let len = match reader.read(unsafe { buf.assume_init_mut() }) {
32            Ok(0) => return Ok(written),
33            Ok(len) => len,
34            Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
35            Err(e) => return Err(e),
36        };
37        writer.write_all(unsafe { &buf.assume_init_ref()[..len] })?;
38        written += len as u64;
39    }
40}
bare_io/util.rs

bare_io/
util.rs
