Backport patches to 0.38

src/backend/libc/event/syscalls.rs

@@ -314,12 +314,19 @@ pub(crate) fn port_getn(
     events: &mut Vec<Event>,
     mut nget: u32,
 ) -> io::Result<()> {
+    // `port_getn` special-cases a max value of 0 to be a query that returns
+    // the number of events. We don't want to do the `set_len` in that case, so
+    // so bail out early if needed.
+    if events.capacity() == 0 {
+        return Ok(());
+    }
+
     let timeout = timeout.map_or(null_mut(), as_mut_ptr);
     unsafe {
         ret(c::port_getn(
             borrowed_fd(port),
             events.as_mut_ptr().cast(),
-            events.len().try_into().unwrap(),
+            events.capacity().try_into().unwrap(),
             &mut nget,
             timeout,
         ))?;
@@ -333,6 +340,24 @@ pub(crate) fn port_getn(
     Ok(())
 }
 
+#[cfg(solarish)]
+pub(crate) fn port_getn_query(port: BorrowedFd<'_>) -> io::Result<u32> {
+    let mut nget: u32 = 0;
+
+    // Pass a `max` of 0 to query the number of available events.
+    unsafe {
+        ret(c::port_getn(
+            borrowed_fd(port),
+            null_mut(),
+            0,
+            &mut nget,
+            null_mut(),
+        ))?;
+    }
+
+    Ok(nget)
+}
+
 #[cfg(solarish)]
 pub(crate) fn port_send(
     port: BorrowedFd<'_>,

src/event/port.rs

@@ -110,6 +110,13 @@ pub fn port_get(port: impl AsFd, timeout: Option<Duration>) -> io::Result<Event>
 /// `port_getn(port, events, min_events, timeout)`—Gets multiple events from a
 /// port.
 ///
+/// This requests up to a max of `events.capacity()` events, and then resizes
+/// `events` to the number of events retrieved. If `events.capacity()` is 0,
+/// this does nothing and returns immediately.
+///
+/// To query the number of events without retrieving any, use
+/// [`port_getn_query`].
+///
 /// # References
 ///  - [OpenSolaris]
 ///  - [illumos]
@@ -138,6 +145,21 @@ pub fn port_getn(
     )
 }
 
+/// `port_getn(port, NULL, 0, NULL)`—Queries the number of events
+/// available from a port.
+///
+/// To retrieve the events, use [`port_getn`].
+///
+/// # References
+///  - [OpenSolaris]
+///  - [illumos]
+///
+/// [OpenSolaris]: https://www.unix.com/man-page/opensolaris/3C/port_getn/
+/// [illumos]: https://illumos.org/man/3C/port_getn
+pub fn port_getn_query(port: impl AsFd) -> io::Result<u32> {
+    syscalls::port_getn_query(port.as_fd())
+}
+
 /// `port_send(port, events, userdata)`—Sends an event to a port.
 ///
 /// # References

src/io_uring.rs

@@ -1433,6 +1433,39 @@ pub struct io_uring_buf {
     pub resv: u16,
 }
 
+#[allow(missing_docs)]
+#[repr(C)]
+#[derive(Debug, Copy, Clone, Default)]
+pub struct buf_ring_tail_struct {
+    pub resv1: u64,
+    pub resv2: u32,
+    pub resv3: u16,
+    pub tail: u16,
+}
+
+#[allow(missing_docs)]
+#[repr(C)]
+#[derive(Debug, Default)]
+pub struct buf_ring_bufs_struct {
+    pub bufs: sys::__IncompleteArrayField<io_uring_buf>,
+}
+
+#[allow(missing_docs)]
+#[repr(C)]
+#[derive(Debug, Default)]
+pub struct tail_or_bufs_struct {
+    pub tail: sys::__BindgenUnionField<buf_ring_tail_struct>,
+    pub bufs: sys::__BindgenUnionField<buf_ring_bufs_struct>,
+    pub union_field: [u64; 2],
+}
+
+#[allow(missing_docs)]
+#[repr(C)]
+#[derive(Debug, Default)]
+pub struct io_uring_buf_ring {
+    pub tail_or_bufs: tail_or_bufs_struct,
+}
+
 impl Default for ioprio_union {
     #[inline]
     fn default() -> Self {
@@ -1599,5 +1632,16 @@ mod tests {
         check_struct!(io_uring_buf_reg, ring_addr, ring_entries, bgid, pad, resv);
         check_struct!(io_uring_buf, addr, len, bid, resv);
         check_struct!(io_uring_sync_cancel_reg, addr, fd, flags, timeout, pad);
+
+        check_renamed_type!(tail_or_bufs_struct, io_uring_buf_ring__bindgen_ty_1);
+        check_renamed_type!(
+            buf_ring_tail_struct,
+            io_uring_buf_ring__bindgen_ty_1__bindgen_ty_1
+        );
+        check_renamed_type!(
+            buf_ring_bufs_struct,
+            io_uring_buf_ring__bindgen_ty_1__bindgen_ty_2
+        );
+        check_struct_renamed_field!(io_uring_buf_ring, tail_or_bufs, __bindgen_anon_1);
     }
 }

tests/fs/main.rs

@@ -12,6 +12,7 @@ mod fcntl;
     target_os = "emscripten",
     target_os = "fuchsia",
     target_os = "redox",
+    target_os = "solaris",
     target_os = "wasi"
 )))]
 mod fcntl_lock;

tests/io_uring/register.rs

@@ -1,10 +1,14 @@
+use std::ptr;
+
 use libc::c_void;
 use rustix::fd::{AsFd, AsRawFd, BorrowedFd};
-use rustix::io::Result;
+use rustix::io::{Errno, Result};
 use rustix::io_uring::{
-    io_uring_params, io_uring_register_with, io_uring_rsrc_update, io_uring_setup,
-    IoringFeatureFlags, IoringRegisterFlags, IoringRegisterOp,
+    io_uring_buf, io_uring_buf_reg, io_uring_buf_ring, io_uring_params, io_uring_register_with,
+    io_uring_rsrc_update, io_uring_setup, IoringFeatureFlags, IoringRegisterFlags,
+    IoringRegisterOp,
 };
+use rustix::mm::{MapFlags, ProtFlags};
 
 fn do_register<FD>(
     fd: FD,
@@ -87,6 +91,19 @@ where
     Ok(())
 }
 
+fn register_buf_ring<FD>(fd: FD, reg: &io_uring_buf_reg) -> Result<()>
+where
+    FD: AsFd,
+{
+    do_register(
+        fd,
+        false,
+        IoringRegisterOp::RegisterPbufRing,
+        reg as *const io_uring_buf_reg as *const c_void,
+        1,
+    )
+}
+
 #[test]
 fn test_io_uring_register_with() {
     let mut params = io_uring_params::default();
@@ -104,3 +121,53 @@ fn test_io_uring_register_with() {
     unregister_ring(ring_fd).unwrap();
     register_result.unwrap();
 }
+
+#[test]
+fn io_uring_buf_ring_can_be_registered() {
+    const ENTRIES: usize = 8;
+    const BGID: u16 = 42;
+
+    let mut params = io_uring_params::default();
+    let ring_fd = io_uring_setup(4, &mut params).unwrap();
+
+    // Test that the kernel version supports IORING_REGISTER_PBUF_RING. If it doesn't, the kernel
+    // will return EINVAL. Not setting a `ring_addr` on `io_uring_buf_reg` will return `EFAULT`.
+    if let Err(e) = register_buf_ring(ring_fd.as_fd(), &io_uring_buf_reg::default()) {
+        if e == Errno::INVAL {
+            // Skip the test, as the current kernel version doesn't support what we need to test.
+            return;
+        }
+    }
+
+    let buf_ring_size = ENTRIES * std::mem::size_of::<io_uring_buf>();
+
+    let br_ptr = unsafe {
+        rustix::mm::mmap_anonymous(
+            ptr::null_mut(),
+            buf_ring_size,
+            ProtFlags::READ | ProtFlags::WRITE,
+            MapFlags::PRIVATE,
+        )
+    }
+    .unwrap() as *mut io_uring_buf_ring;
+
+    let br = unsafe { br_ptr.as_mut() }.expect("A valid io_uring_buf_ring struct");
+
+    let reg = io_uring_buf_reg {
+        ring_addr: br_ptr as u64,
+        ring_entries: ENTRIES as u32,
+        bgid: BGID,
+        pad: 0,
+        resv: [0u64; 3],
+    };
+
+    assert_eq!(register_buf_ring(ring_fd, &reg), Ok(()));
+
+    let tail = unsafe { br.tail_or_bufs.tail.as_mut() };
+    tail.tail = 0;
+    let bufs = unsafe { br.tail_or_bufs.bufs.as_mut().bufs.as_mut_slice(ENTRIES) };
+
+    assert_eq!(bufs[0].bid, 0);
+    bufs[7].bid = 7;
+    assert_eq!(bufs[7].bid, 7);
+}