1 files changed, 219 insertions, 0 deletions
diff --git a/src/runtime/netpoll_kqueue.go b/src/runtime/netpoll_kqueue.go
new file mode 100644
index 0000000..d774dce
--- /dev/null
+++ b/src/runtime/netpoll_kqueue.go
@@ -0,0 +1,219 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build darwin || dragonfly || freebsd || netbsd || openbsd
+
+package runtime
+
+// Integrated network poller (kqueue-based implementation).
+
+import (
+	"internal/goarch"
+	"runtime/internal/atomic"
+	"unsafe"
+)
+
+var (
+	kq int32 = -1
+
+	netpollBreakRd, netpollBreakWr uintptr // for netpollBreak
+
+	netpollWakeSig atomic.Uint32 // used to avoid duplicate calls of netpollBreak
+)
+
+func netpollinit() {
+	kq = kqueue()
+	if kq < 0 {
+		println("runtime: kqueue failed with", -kq)
+		throw("runtime: netpollinit failed")
+	}
+	closeonexec(kq)
+	r, w, errno := nonblockingPipe()
+	if errno != 0 {
+		println("runtime: pipe failed with", -errno)
+		throw("runtime: pipe failed")
+	}
+	ev := keventt{
+		filter: _EVFILT_READ,
+		flags:  _EV_ADD,
+	}
+	*(*uintptr)(unsafe.Pointer(&ev.ident)) = uintptr(r)
+	n := kevent(kq, &ev, 1, nil, 0, nil)
+	if n < 0 {
+		println("runtime: kevent failed with", -n)
+		throw("runtime: kevent failed")
+	}
+	netpollBreakRd = uintptr(r)
+	netpollBreakWr = uintptr(w)
+}
+
+func netpollIsPollDescriptor(fd uintptr) bool {
+	return fd == uintptr(kq) || fd == netpollBreakRd || fd == netpollBreakWr
+}
+
+func netpollopen(fd uintptr, pd *pollDesc) int32 {
+	// Arm both EVFILT_READ and EVFILT_WRITE in edge-triggered mode (EV_CLEAR)
+	// for the whole fd lifetime. The notifications are automatically unregistered
+	// when fd is closed.
+	var ev [2]keventt
+	*(*uintptr)(unsafe.Pointer(&ev[0].ident)) = fd
+	ev[0].filter = _EVFILT_READ
+	ev[0].flags = _EV_ADD | _EV_CLEAR
+	ev[0].fflags = 0
+	ev[0].data = 0
+
+	if goarch.PtrSize == 4 {
+		// We only have a pointer-sized field to store into,
+		// so on a 32-bit system we get no sequence protection.
+		// TODO(iant): If we notice any problems we could at least
+		// steal the low-order 2 bits for a tiny sequence number.
+		ev[0].udata = (*byte)(unsafe.Pointer(pd))
+	} else {
+		tp := taggedPointerPack(unsafe.Pointer(pd), pd.fdseq.Load())
+		ev[0].udata = (*byte)(unsafe.Pointer(uintptr(tp)))
+	}
+	ev[1] = ev[0]
+	ev[1].filter = _EVFILT_WRITE
+	n := kevent(kq, &ev[0], 2, nil, 0, nil)
+	if n < 0 {
+		return -n
+	}
+	return 0
+}
+
+func netpollclose(fd uintptr) int32 {
+	// Don't need to unregister because calling close()
+	// on fd will remove any kevents that reference the descriptor.
+	return 0
+}
+
+func netpollarm(pd *pollDesc, mode int) {
+	throw("runtime: unused")
+}
+
+// netpollBreak interrupts a kevent.
+func netpollBreak() {
+	// Failing to cas indicates there is an in-flight wakeup, so we're done here.
+	if !netpollWakeSig.CompareAndSwap(0, 1) {
+		return
+	}
+
+	for {
+		var b byte
+		n := write(netpollBreakWr, unsafe.Pointer(&b), 1)
+		if n == 1 || n == -_EAGAIN {
+			break
+		}
+		if n == -_EINTR {
+			continue
+		}
+		println("runtime: netpollBreak write failed with", -n)
+		throw("runtime: netpollBreak write failed")
+	}
+}
+
+// netpoll checks for ready network connections.
+// Returns list of goroutines that become runnable.
+// delay < 0: blocks indefinitely
+// delay == 0: does not block, just polls
+// delay > 0: block for up to that many nanoseconds
+func netpoll(delay int64) (gList, int32) {
+	if kq == -1 {
+		return gList{}, 0
+	}
+	var tp *timespec
+	var ts timespec
+	if delay < 0 {
+		tp = nil
+	} else if delay == 0 {
+		tp = &ts
+	} else {
+		ts.setNsec(delay)
+		if ts.tv_sec > 1e6 {
+			// Darwin returns EINVAL if the sleep time is too long.
+			ts.tv_sec = 1e6
+		}
+		tp = &ts
+	}
+	var events [64]keventt
+retry:
+	n := kevent(kq, nil, 0, &events[0], int32(len(events)), tp)
+	if n < 0 {
+		// Ignore the ETIMEDOUT error for now, but try to dive deep and
+		// figure out what really happened with n == ETIMEOUT,
+		// see https://go.dev/issue/59679 for details.
+		if n != -_EINTR && n != -_ETIMEDOUT {
+			println("runtime: kevent on fd", kq, "failed with", -n)
+			throw("runtime: netpoll failed")
+		}
+		// If a timed sleep was interrupted, just return to
+		// recalculate how long we should sleep now.
+		if delay > 0 {
+			return gList{}, 0
+		}
+		goto retry
+	}
+	var toRun gList
+	delta := int32(0)
+	for i := 0; i < int(n); i++ {
+		ev := &events[i]
+
+		if uintptr(ev.ident) == netpollBreakRd {
+			if ev.filter != _EVFILT_READ {
+				println("runtime: netpoll: break fd ready for", ev.filter)
+				throw("runtime: netpoll: break fd ready for something unexpected")
+			}
+			if delay != 0 {
+				// netpollBreak could be picked up by a
+				// nonblocking poll. Only read the byte
+				// if blocking.
+				var tmp [16]byte
+				read(int32(netpollBreakRd), noescape(unsafe.Pointer(&tmp[0])), int32(len(tmp)))
+				netpollWakeSig.Store(0)
+			}
+			continue
+		}
+
+		var mode int32
+		switch ev.filter {
+		case _EVFILT_READ:
+			mode += 'r'
+
+			// On some systems when the read end of a pipe
+			// is closed the write end will not get a
+			// _EVFILT_WRITE event, but will get a
+			// _EVFILT_READ event with EV_EOF set.
+			// Note that setting 'w' here just means that we
+			// will wake up a goroutine waiting to write;
+			// that goroutine will try the write again,
+			// and the appropriate thing will happen based
+			// on what that write returns (success, EPIPE, EAGAIN).
+			if ev.flags&_EV_EOF != 0 {
+				mode += 'w'
+			}
+		case _EVFILT_WRITE:
+			mode += 'w'
+		}
+		if mode != 0 {
+			var pd *pollDesc
+			var tag uintptr
+			if goarch.PtrSize == 4 {
+				// No sequence protection on 32-bit systems.
+				// See netpollopen for details.
+				pd = (*pollDesc)(unsafe.Pointer(ev.udata))
+				tag = 0
+			} else {
+				tp := taggedPointer(uintptr(unsafe.Pointer(ev.udata)))
+				pd = (*pollDesc)(tp.pointer())
+				tag = tp.tag()
+				if pd.fdseq.Load() != tag {
+					continue
+				}
+			}
+			pd.setEventErr(ev.flags == _EV_ERROR, tag)
+			delta += netpollready(&toRun, pd, mode)
+		}
+	}
+	return toRun, delta
+}