snapshot: sagernet/gvisor v0.0.0-20250811.0-sing-box-mod.1

Содержимое пина, зафиксированного в go.mod sing-box-lx, одним коммитом
без истории. Полная история SagerNet/gvisor — 1.45 ГБ и клонируется в
каждой CI-джобе; наша дельта — одна вставка в одну функцию, история для
неё не нужна.

Module path github.com/sagernet/gvisor сохранён намеренно: на него
опирается replace-директива суперпроекта.

Патч поверх — отдельным коммитом, чтобы дельта читалась одним git show
и переносилась на новый пин копированием.

SPECS/TASKS/048-GVISOR_HANDSHAKE_NIL_CRASH

pkg/flipcall/futex_linux.go

@@ -0,0 +1,88 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build linux
+// +build linux
+
+package flipcall
+
+import (
+	"fmt"
+	"runtime"
+
+	"github.com/sagernet/gvisor/pkg/abi/linux"
+	"golang.org/x/sys/unix"
+)
+
+func (ep *Endpoint) futexSetPeerActive() error {
+	if ep.connState().CompareAndSwap(ep.activeState, ep.inactiveState) {
+		return nil
+	}
+	switch cs := ep.connState().Load(); cs {
+	case csShutdown:
+		return ShutdownError{}
+	default:
+		return fmt.Errorf("unexpected connection state before FUTEX_WAKE: %v", cs)
+	}
+}
+
+func (ep *Endpoint) futexWakePeer() error {
+	if err := ep.futexWakeConnState(1); err != nil {
+		return fmt.Errorf("failed to FUTEX_WAKE peer Endpoint: %v", err)
+	}
+	return nil
+}
+
+func (ep *Endpoint) futexWaitUntilActive() error {
+	for {
+		switch cs := ep.connState().Load(); cs {
+		case ep.activeState:
+			return nil
+		case ep.inactiveState:
+			if ep.isShutdownLocally() {
+				return ShutdownError{}
+			}
+			if err := ep.futexWaitConnState(ep.inactiveState); err != nil {
+				return fmt.Errorf("failed to FUTEX_WAIT for peer Endpoint: %v", err)
+			}
+			continue
+		case csShutdown:
+			return ShutdownError{}
+		default:
+			return fmt.Errorf("unexpected connection state before FUTEX_WAIT: %v", cs)
+		}
+	}
+}
+
+func (ep *Endpoint) futexWakeConnState(numThreads int32) error {
+	if _, _, e := unix.RawSyscall(unix.SYS_FUTEX, ep.packet, linux.FUTEX_WAKE, uintptr(numThreads)); e != 0 {
+		return e
+	}
+	return nil
+}
+
+func (ep *Endpoint) futexWaitConnState(curState uint32) error {
+	_, _, e := unix.Syscall6(unix.SYS_FUTEX, ep.packet, linux.FUTEX_WAIT, uintptr(curState), 0, 0, 0)
+	if e != 0 && e != unix.EAGAIN && e != unix.EINTR {
+		return e
+	}
+	return nil
+}
+
+func yieldThread() {
+	unix.Syscall(unix.SYS_SCHED_YIELD, 0, 0, 0)
+	// The thread we're trying to yield to may be waiting for a Go runtime P.
+	// runtime.Gosched() will hand off ours if necessary.
+	runtime.Gosched()
+}