Drop Windows support.

Windows has a different `FD_SET` representation. Supporting it might be
possible, though the documentation is ambiguous about whether it supports
arbitrary `FD_SETSIZE` values. But even if so, it would require a more
elaborate abstraction, so just drop it for now.

src/backend/libc/event/syscalls.rs

@@ -166,7 +166,7 @@ pub(crate) unsafe fn select(
         Some(timeout) => {
             // Convert from `Timespec` to `c::timeval`.
             timeout_data = c::timeval {
-                tv_sec: timeout.tv_sec.try_into().map_err(|_| io::Errno::OVERFLOW)?,
+                tv_sec: timeout.tv_sec,
                 tv_usec: ((timeout.tv_nsec + 999) / 1000) as _,
             };
             &timeout_data

src/backend/libc/event/windows_syscalls.rs

@@ -2,8 +2,7 @@
 
 use crate::backend::c;
 use crate::backend::conv::ret_c_int;
-use crate::event::{FdSetElement, PollFd};
-use crate::fd::RawFd;
+use crate::event::PollFd;
 use crate::io;
 
 pub(crate) fn poll(fds: &mut [PollFd<'_>], timeout: c::c_int) -> io::Result<usize> {
@@ -15,63 +14,3 @@ pub(crate) fn poll(fds: &mut [PollFd<'_>], timeout: c::c_int) -> io::Result<usiz
     ret_c_int(unsafe { c::poll(fds.as_mut_ptr().cast(), nfds, timeout) })
         .map(|nready| nready as usize)
 }
-
-pub(crate) fn select(
-    nfds: i32,
-    readfds: Option<&mut [FdSetElement]>,
-    writefds: Option<&mut [FdSetElement]>,
-    exceptfds: Option<&mut [FdSetElement]>,
-    timeout: Option<&crate::timespec::Timespec>,
-) -> io::Result<i32> {
-    use core::ptr::{null, null_mut};
-
-    let len = crate::event::fd_set_num_elements(nfds as RawFd);
-
-    let readfds = match readfds {
-        Some(readfds) => {
-            assert!(readfds.len() >= len);
-            readfds.as_mut_ptr()
-        }
-        None => null_mut(),
-    };
-    let writefds = match writefds {
-        Some(writefds) => {
-            assert!(writefds.len() >= len);
-            writefds.as_mut_ptr()
-        }
-        None => null_mut(),
-    };
-    let exceptfds = match exceptfds {
-        Some(exceptfds) => {
-            assert!(exceptfds.len() >= len);
-            exceptfds.as_mut_ptr()
-        }
-        None => null_mut(),
-    };
-
-    let timeout_data;
-    let timeout_ptr = match timeout {
-        Some(timeout) => {
-            // Convert from `Timespec` to `TIMEVAL`.
-            timeout_data = c::TIMEVAL {
-                tv_sec: timeout
-                    .tv_sec
-                    .try_into()
-                    .map_err(|_| io::Errno::OPNOTSUPP)?,
-                tv_usec: ((timeout.tv_nsec + 999) / 1000) as _,
-            };
-            &timeout_data
-        }
-        None => null(),
-    };
-
-    unsafe {
-        ret_c_int(c::select(
-            nfds,
-            readfds.cast(),
-            writefds.cast(),
-            exceptfds.cast(),
-            timeout_ptr,
-        ))
-    }
-}

src/backend/libc/winsock_c.rs

@@ -57,9 +57,3 @@ pub(crate) use WinSock::{
     WSAEWOULDBLOCK as EWOULDBLOCK, WSAEWOULDBLOCK as EAGAIN, WSAPOLLFD as pollfd,
     WSA_E_CANCELLED as ECANCELED, *,
 };
-
-pub struct timespec {
-    pub tv_sec: time_t,
-    pub tv_nsec: i64,
-}
-pub type time_t = i64;

src/event/mod.rs

@@ -16,7 +16,7 @@ mod pause;
 mod poll;
 #[cfg(solarish)]
 pub mod port;
-#[cfg(any(bsd, linux_kernel, windows))]
+#[cfg(any(bsd, linux_kernel))]
 mod select;
 
 #[cfg(any(
@@ -29,5 +29,5 @@ pub use eventfd::{eventfd, EventfdFlags};
 #[cfg(not(any(windows, target_os = "redox", target_os = "wasi")))]
 pub use pause::*;
 pub use poll::{poll, PollFd, PollFlags};
-#[cfg(any(bsd, linux_kernel, windows))]
+#[cfg(any(bsd, linux_kernel))]
 pub use select::*;

src/event/select.rs

@@ -47,6 +47,9 @@ pub type FdSetElement = u32;
 /// this platform always has an `FD_SETSIZE` limitation, following POSIX. This
 /// platform's documentation recommends using [`poll`] instead.
 ///
+/// On Windows, this function is not defined because the `select` function on
+/// this platform doesn't use bitvectors for file descriptor sets.
+///
 /// [`poll`]: crate::event::poll()
 ///
 /// # Safety
@@ -61,7 +64,6 @@ pub type FdSetElement = u32;
 ///  - [NetBSD]
 ///  - [OpenBSD]
 ///  - [DragonFly BSD]
-///  - [Winsock]
 ///  - [glibc]
 ///
 ///  [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/select.html
@@ -71,7 +73,6 @@ pub type FdSetElement = u32;
 ///  [NetBSD]: https://man.netbsd.org/select.2
 ///  [OpenBSD]: https://man.openbsd.org/select.2
 ///  [DragonFly BSD]: https://man.dragonflybsd.org/?command=select&section=2
-///  [Winsock]: https://learn.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-select
 ///  [glibc]: https://sourceware.org/glibc/manual/latest/html_node/Waiting-for-I_002fO.html#index-select
 pub unsafe fn select(
     nfds: i32,

src/lib.rs

@@ -356,13 +356,14 @@ mod prctl;
 #[cfg(not(any(windows, target_os = "espidf", target_os = "wasi")))]
 #[cfg(any(feature = "process", feature = "runtime", all(bsd, feature = "event")))]
 mod signal;
+#[cfg(not(windows))]
 #[cfg(any(
     feature = "fs",
     feature = "process",
     feature = "runtime",
     feature = "thread",
     feature = "time",
-    all(feature = "event", any(bsd, linux_kernel, windows)),
+    all(feature = "event", any(bsd, linux_kernel)),
     all(
         linux_raw,
         not(feature = "use-libc-auxv"),

tests/event/main.rs

@@ -10,5 +10,5 @@ mod epoll;
 #[cfg(not(target_os = "wasi"))]
 mod eventfd;
 mod poll;
-#[cfg(any(bsd, linux_kernel, windows))]
+#[cfg(any(bsd, linux_kernel))]
 mod select;

tests/event/select.rs

@@ -4,7 +4,6 @@ use rustix::event::{
 };
 use rustix::fd::RawFd;
 #[cfg(feature = "pipe")]
-#[cfg(not(windows))]
 use {
     rustix::event::{select, Timespec},
     rustix::fd::{AsRawFd, FromRawFd, OwnedFd},
@@ -13,7 +12,6 @@ use {
 };
 
 #[cfg(feature = "pipe")]
-#[cfg(not(windows))]
 #[test]
 fn test_select() {
     use rustix::io::{read, write};
@@ -84,7 +82,6 @@ fn test_select() {
 }
 
 #[cfg(feature = "pipe")]
-#[cfg(not(windows))]
 #[test]
 fn test_select_with_great_fds() {
     use core::cmp::max;