diff options
Diffstat (limited to 'src/macros/select.rs')
| -rw-r--r-- | src/macros/select.rs | 31 |
1 files changed, 23 insertions, 8 deletions
diff --git a/src/macros/select.rs b/src/macros/select.rs index 051f8cb..7ba04a0 100644 --- a/src/macros/select.rs +++ b/src/macros/select.rs @@ -101,6 +101,7 @@ /// * [`tokio::sync::watch::Receiver::changed`](crate::sync::watch::Receiver::changed) /// * [`tokio::net::TcpListener::accept`](crate::net::TcpListener::accept) /// * [`tokio::net::UnixListener::accept`](crate::net::UnixListener::accept) +/// * [`tokio::signal::unix::Signal::recv`](crate::signal::unix::Signal::recv) /// * [`tokio::io::AsyncReadExt::read`](crate::io::AsyncReadExt::read) on any `AsyncRead` /// * [`tokio::io::AsyncReadExt::read_buf`](crate::io::AsyncReadExt::read_buf) on any `AsyncRead` /// * [`tokio::io::AsyncWriteExt::write`](crate::io::AsyncWriteExt::write) on any `AsyncWrite` @@ -429,7 +430,8 @@ macro_rules! select { // // This module is defined within a scope and should not leak out of this // macro. - mod util { + #[doc(hidden)] + mod __tokio_select_util { // Generate an enum with one variant per select branch $crate::select_priv_declare_output_enum!( ( $($count)* ) ); } @@ -442,13 +444,13 @@ macro_rules! select { const BRANCHES: u32 = $crate::count!( $($count)* ); - let mut disabled: util::Mask = Default::default(); + let mut disabled: __tokio_select_util::Mask = Default::default(); // First, invoke all the pre-conditions. For any that return true, // set the appropriate bit in `disabled`. $( if !$c { - let mask: util::Mask = 1 << $crate::count!( $($skip)* ); + let mask: __tokio_select_util::Mask = 1 << $crate::count!( $($skip)* ); disabled |= mask; } )* @@ -458,8 +460,18 @@ macro_rules! select { let mut output = { // Safety: Nothing must be moved out of `futures`. This is to // satisfy the requirement of `Pin::new_unchecked` called below. + // + // We can't use the `pin!` macro for this because `futures` is a + // tuple and the standard library provides no way to pin-project to + // the fields of a tuple. let mut futures = ( $( $fut , )+ ); + // This assignment makes sure that the `poll_fn` closure only has a + // reference to the futures, instead of taking ownership of them. + // This mitigates the issue described in + // <https://internals.rust-lang.org/t/surprising-soundness-trouble-around-pollfn/17484> + let mut futures = &mut futures; + $crate::macros::support::poll_fn(|cx| { // Track if any branch returns pending. If no branch completes // **or** returns pending, this implies that all branches are @@ -495,7 +507,7 @@ macro_rules! select { // Extract the future for this branch from the // tuple - let ( $($skip,)* fut, .. ) = &mut futures; + let ( $($skip,)* fut, .. ) = &mut *futures; // Safety: future is stored on the stack above // and never moved. @@ -525,7 +537,7 @@ macro_rules! select { } // The select is complete, return the value - return Ready($crate::select_variant!(util::Out, ($($skip)*))(out)); + return Ready($crate::select_variant!(__tokio_select_util::Out, ($($skip)*))(out)); } )* _ => unreachable!("reaching this means there probably is an off by one bug"), @@ -536,16 +548,16 @@ macro_rules! select { Pending } else { // All branches have been disabled. - Ready(util::Out::Disabled) + Ready(__tokio_select_util::Out::Disabled) } }).await }; match output { $( - $crate::select_variant!(util::Out, ($($skip)*) ($bind)) => $handle, + $crate::select_variant!(__tokio_select_util::Out, ($($skip)*) ($bind)) => $handle, )* - util::Out::Disabled => $else, + __tokio_select_util::Out::Disabled => $else, _ => unreachable!("failed to match bind"), } }}; @@ -801,6 +813,9 @@ macro_rules! count { (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { 63 }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 64 + }; } #[macro_export] |