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// Copyright 2020 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use std::mem::size_of;
use std::os::unix::io::RawFd;
use crate::{MsgOnSocket, MsgResult};
use super::{simple_read, simple_write};
// Returns the size of one part of a tuple.
fn tuple_size_helper<T: MsgOnSocket>(v: &T) -> usize {
T::fixed_size().unwrap_or_else(|| v.msg_size() + size_of::<u64>())
}
unsafe fn tuple_read_helper<T: MsgOnSocket>(
buffer: &[u8],
fds: &[RawFd],
buffer_index: &mut usize,
fd_index: &mut usize,
) -> MsgResult<T> {
let end = match T::fixed_size() {
Some(_) => buffer.len(),
None => {
let len = simple_read::<u64>(buffer, buffer_index)? as usize;
*buffer_index + len
}
};
let (v, fd_read) = T::read_from_buffer(&buffer[*buffer_index..end], &fds[*fd_index..])?;
*buffer_index += v.msg_size();
*fd_index += fd_read;
Ok(v)
}
fn tuple_write_helper<T: MsgOnSocket>(
v: &T,
buffer: &mut [u8],
fds: &mut [RawFd],
buffer_index: &mut usize,
fd_index: &mut usize,
) -> MsgResult<()> {
let end = match T::fixed_size() {
Some(_) => buffer.len(),
None => {
let len = v.msg_size();
simple_write(len as u64, buffer, buffer_index)?;
*buffer_index + len
}
};
let fd_written = v.write_to_buffer(&mut buffer[*buffer_index..end], &mut fds[*fd_index..])?;
*buffer_index += v.msg_size();
*fd_index += fd_written;
Ok(())
}
macro_rules! tuple_impls {
() => {};
($t: ident) => {
#[allow(unused_variables, non_snake_case)]
impl<$t: MsgOnSocket> MsgOnSocket for ($t,) {
fn uses_fd() -> bool {
$t::uses_fd()
}
fn fd_count(&self) -> usize {
self.0.fd_count()
}
fn fixed_size() -> Option<usize> {
$t::fixed_size()
}
fn msg_size(&self) -> usize {
self.0.msg_size()
}
unsafe fn read_from_buffer(buffer: &[u8], fds: &[RawFd]) -> MsgResult<(Self, usize)> {
let (t, s) = $t::read_from_buffer(buffer, fds)?;
Ok(((t,), s))
}
fn write_to_buffer(
&self,
buffer: &mut [u8],
fds: &mut [RawFd],
) -> MsgResult<usize> {
self.0.write_to_buffer(buffer, fds)
}
}
};
($t: ident, $($ts:ident),*) => {
#[allow(unused_variables, non_snake_case)]
impl<$t: MsgOnSocket $(, $ts: MsgOnSocket)*> MsgOnSocket for ($t$(, $ts)*) {
fn uses_fd() -> bool {
$t::uses_fd() $(|| $ts::uses_fd())*
}
fn fd_count(&self) -> usize {
if Self::uses_fd() {
return 0;
}
let ($t $(,$ts)*) = self;
$t.fd_count() $(+ $ts.fd_count())*
}
fn fixed_size() -> Option<usize> {
// Returns None if any element is not fixed size.
Some($t::fixed_size()? $(+ $ts::fixed_size()?)*)
}
fn msg_size(&self) -> usize {
if let Some(size) = Self::fixed_size() {
return size
}
let ($t $(,$ts)*) = self;
tuple_size_helper($t) $(+ tuple_size_helper($ts))*
}
unsafe fn read_from_buffer(buffer: &[u8], fds: &[RawFd]) -> MsgResult<(Self, usize)> {
let mut buffer_index = 0;
let mut fd_index = 0;
Ok((
(
tuple_read_helper(buffer, fds, &mut buffer_index, &mut fd_index)?,
$({
// Dummy let used to trigger the correct number of iterations.
let $ts = ();
tuple_read_helper(buffer, fds, &mut buffer_index, &mut fd_index)?
},)*
),
fd_index
))
}
fn write_to_buffer(
&self,
buffer: &mut [u8],
fds: &mut [RawFd],
) -> MsgResult<usize> {
let mut buffer_index = 0;
let mut fd_index = 0;
let ($t $(,$ts)*) = self;
tuple_write_helper($t, buffer, fds, &mut buffer_index, &mut fd_index)?;
$(
tuple_write_helper($ts, buffer, fds, &mut buffer_index, &mut fd_index)?;
)*
Ok(fd_index)
}
}
tuple_impls!{ $($ts),* }
}
}
// Imlpement tuple for up to 8 elements.
tuple_impls! { A, B, C, D, E, F, G, H }
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn read_write_1_fixed() {
let tuple = (1,);
let mut buffer = vec![0; tuple.msg_size()];
tuple.write_to_buffer(&mut buffer, &mut []).unwrap();
let read_tuple = unsafe { <(u32,)>::read_from_buffer(&buffer, &[]) }
.unwrap()
.0;
assert_eq!(tuple, read_tuple);
}
#[test]
fn read_write_8_fixed() {
let tuple = (1u32, 2u8, 3u16, 4u64, 5u32, 6u16, 7u8, 8u8);
let mut buffer = vec![0; tuple.msg_size()];
tuple.write_to_buffer(&mut buffer, &mut []).unwrap();
let read_tuple = unsafe { <_>::read_from_buffer(&buffer, &[]) }.unwrap().0;
assert_eq!(tuple, read_tuple);
}
#[test]
fn read_write_1() {
let tuple = (Some(1u64),);
let mut buffer = vec![0; tuple.msg_size()];
tuple.write_to_buffer(&mut buffer, &mut []).unwrap();
let read_tuple = unsafe { <_>::read_from_buffer(&buffer, &[]) }.unwrap().0;
assert_eq!(tuple, read_tuple);
}
#[test]
fn read_write_4() {
let tuple = (Some(12u16), Some(false), None::<u8>, None::<u64>);
let mut buffer = vec![0; tuple.msg_size()];
println!("{:?}", tuple.msg_size());
tuple.write_to_buffer(&mut buffer, &mut []).unwrap();
let read_tuple = unsafe { <_>::read_from_buffer(&buffer, &[]) }.unwrap().0;
assert_eq!(tuple, read_tuple);
}
}
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