Fix the size of FdSetElement on 32-bit Windows. (#1381)

On rustix on Windows, `RawFd` is `SOCKET`, which is the size of `usize`,
so make `FdSet` 32-bit on 32-bitt Windows to match it.

Author: sunfishcode

.github/workflows/main.yml

@@ -82,6 +82,7 @@ jobs:
         sparcv9-sun-solaris
         aarch64-linux-android
         aarch64-apple-ios
+        i686-pc-windows-msvc
     - if: matrix.rust != '1.63'
       run: >
         rustup target add
@@ -132,6 +133,7 @@ jobs:
     - run: cargo check --workspace --release -vv --target=sparcv9-sun-solaris --features=all-apis --all-targets
     - run: cargo check --workspace --release -vv --target=aarch64-apple-ios --features=all-apis --all-targets
     - run: cargo check --workspace --release -vv --target=aarch64-linux-android --features=all-apis --all-targets
+    - run: cargo check --workspace --release -vv --target=i686-pc-windows-msvc --features=all-apis --all-targets
 
   check_no_default_features:
     name: Check --no-default-features

Cargo.toml

@@ -73,6 +73,10 @@ memoffset = "0.9.0"
 flate2 = "1.0"
 static_assertions = "1.1.0"
 
+# With Rust 1.70 this can be removed in favor of `std::sync::OnceLock`.
+[target.'cfg(windows)'.dev-dependencies]
+once_cell = "1.20.3"
+
 [target.'cfg(all(criterion, not(any(target_os = "emscripten", target_os = "wasi"))))'.dev-dependencies]
 criterion = "0.4"
 

src/backend/libc/mod.rs

@@ -79,11 +79,11 @@ pub(crate) mod fd {
     /// [`AsFd`]: https://doc.rust-lang.org/stable/std/os/fd/trait.AsFd.html
     pub trait AsFd {
         /// An `as_fd` function for Winsock, where an `Fd` is a `Socket`.
-        fn as_fd(&self) -> BorrowedFd;
+        fn as_fd(&self) -> BorrowedFd<'_>;
     }
     impl<T: AsSocket> AsFd for T {
         #[inline]
-        fn as_fd(&self) -> BorrowedFd {
+        fn as_fd(&self) -> BorrowedFd<'_> {
             self.as_socket()
         }
     }

src/backend/libc/net/sockopt.rs

@@ -1002,7 +1002,7 @@ pub(crate) fn tcp_congestion(fd: BorrowedFd<'_>) -> io::Result<String> {
     unsafe {
         let value = value.assume_init();
         let slice: &[u8] = core::mem::transmute(&value[..optlen as usize]);
-        assert!(slice.iter().any(|b| *b == b'\0'));
+        assert!(slice.contains(&b'\0'));
         Ok(
             core::str::from_utf8(CStr::from_ptr(slice.as_ptr().cast()).to_bytes())
                 .unwrap()

src/backend/linux_raw/net/sockopt.rs

@@ -809,7 +809,7 @@ pub(crate) fn tcp_congestion(fd: BorrowedFd<'_>) -> io::Result<String> {
     unsafe {
         let value = value.assume_init();
         let slice: &[u8] = core::mem::transmute(&value[..optlen as usize]);
-        assert!(slice.iter().any(|b| *b == b'\0'));
+        assert!(slice.contains(&b'\0'));
         Ok(
             core::str::from_utf8(CStr::from_ptr(slice.as_ptr().cast()).to_bytes())
                 .unwrap()

src/event/select.rs

@@ -13,8 +13,6 @@ use crate::{backend, io};
 #[cfg(any(windows, target_os = "wasi"))]
 use core::mem::align_of;
 use core::mem::size_of;
-#[cfg(any(windows, target_os = "wasi"))]
-use core::slice;
 
 /// wasi-libc's `fd_set` type. The libc bindings for it have private fields, so
 /// we redeclare it for ourselves so that we can access the fields. They're
@@ -32,12 +30,9 @@ struct FD_SET {
 use windows_sys::Win32::Networking::WinSock::FD_SET;
 
 /// Storage element type for use with [`select`].
-#[cfg(any(
-    windows,
-    all(
-        target_pointer_width = "64",
-        any(target_os = "freebsd", target_os = "dragonfly")
-    )
+#[cfg(all(
+    target_pointer_width = "64",
+    any(windows, target_os = "freebsd", target_os = "dragonfly")
 ))]
 #[repr(transparent)]
 #[derive(Copy, Clone, Default)]
@@ -52,11 +47,10 @@ pub struct FdSetElement(pub(crate) c::c_ulong);
 /// Storage element type for use with [`select`].
 #[cfg(not(any(
     linux_like,
-    windows,
     target_os = "wasi",
     all(
         target_pointer_width = "64",
-        any(target_os = "freebsd", target_os = "dragonfly")
+        any(windows, target_os = "freebsd", target_os = "dragonfly")
     )
 )))]
 #[repr(transparent)]
@@ -145,12 +139,10 @@ pub fn fd_set_insert(fds: &mut [FdSetElement], fd: RawFd) {
     {
         let set = unsafe { &mut *fds.as_mut_ptr().cast::<FD_SET>() };
         let fd_count = set.fd_count;
-        let fd_array = unsafe { slice::from_raw_parts(set.fd_array.as_ptr(), fd_count as usize) };
+        let fd_array = &set.fd_array[..fd_count as usize];
 
-        if !fd_array.iter().any(|p| *p as RawFd == fd) {
-            let fd_array = unsafe {
-                slice::from_raw_parts_mut(set.fd_array.as_mut_ptr(), fd_count as usize + 1)
-            };
+        if !fd_array.contains(&(fd as _)) {
+            let fd_array = &mut set.fd_array[..fd_count as usize + 1];
             set.fd_count = fd_count + 1;
             fd_array[fd_count as usize] = fd as _;
         }
@@ -171,7 +163,7 @@ pub fn fd_set_remove(fds: &mut [FdSetElement], fd: RawFd) {
     {
         let set = unsafe { &mut *fds.as_mut_ptr().cast::<FD_SET>() };
         let fd_count = set.fd_count;
-        let fd_array = unsafe { slice::from_raw_parts(set.fd_array.as_ptr(), fd_count as usize) };
+        let fd_array = &set.fd_array[..fd_count as usize];
 
         if let Some(pos) = fd_array.iter().position(|p| *p as RawFd == fd) {
             set.fd_count = fd_count - 1;
@@ -197,7 +189,7 @@ pub fn fd_set_bound(fds: &[FdSetElement]) -> RawFd {
     {
         let set = unsafe { &*fds.as_ptr().cast::<FD_SET>() };
         let fd_count = set.fd_count;
-        let fd_array = unsafe { slice::from_raw_parts(set.fd_array.as_ptr(), fd_count as usize) };
+        let fd_array = &set.fd_array[..fd_count as usize];
         let mut max = 0;
         for fd in fd_array {
             if *fd >= max {
@@ -334,7 +326,7 @@ impl<'a> Iterator for FdSetIter<'a> {
 
         let set = unsafe { &*self.fds.as_ptr().cast::<FD_SET>() };
         let fd_count = set.fd_count;
-        let fd_array = unsafe { slice::from_raw_parts(set.fd_array.as_ptr(), fd_count as usize) };
+        let fd_array = &set.fd_array[..fd_count as usize];
 
         if current == fd_count as usize {
             return None;

tests/event/main.rs

@@ -21,7 +21,8 @@ mod select;
 
 #[cfg(windows)]
 mod windows {
-    use std::sync::OnceLock;
+    // With Rust 1.70 this can be `std::sync::OnceLock`.
+    use once_cell::sync::OnceCell as OnceLock;
 
     pub struct Thing;
 

tests/event/select.rs

@@ -104,8 +104,8 @@ fn test_select_with_great_fds() {
     }
     setrlimit(Resource::Nofile, rlimit).unwrap();
 
-    // Create a fd at `FD_SETSIZE + 1` out of thin air. Use `libc` instead of
-    // `OwnedFd::from_raw_fd` because grabbing a fd out of thin air violates
+    // Create an fd at `FD_SETSIZE + 1` out of thin air. Use `libc` instead of
+    // `OwnedFd::from_raw_fd` because grabbing an fd out of thin air violates
     // Rust's concept of I/O safety (and wouldn't make sense to do in anything
     // other than a test like this).
     let great_fd = unsafe { libc::dup2(reader.as_raw_fd(), libc::FD_SETSIZE as RawFd + 1) };

tests/net/main.rs

@@ -26,7 +26,8 @@ mod v6;
 
 #[cfg(windows)]
 mod windows {
-    use std::sync::OnceLock;
+    // With Rust 1.70 this can be `std::sync::OnceLock`.
+    use once_cell::sync::OnceCell as OnceLock;
 
     pub struct Thing;