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/cleanup/cleanup.go

@@ -0,0 +1,61 @@
+// Copyright 2020 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.
+
+// Package cleanup provides utilities to clean "stuff" on defers.
+package cleanup
+
+// Cleanup allows defers to be aborted when cleanup needs to happen
+// conditionally. Usage:
+//
+//		 cu := cleanup.Make(func() { f.Close() })
+//		 defer cu.Clean() // failure before release is called will close the file.
+//		 ...
+//	   cu.Add(func() { f2.Close() })  // Adds another cleanup function
+//	   ...
+//		 cu.Release() // on success, aborts closing the file.
+//		 return f
+type Cleanup struct {
+	cleaners []func()
+}
+
+// Make creates a new Cleanup object.
+func Make(f func()) Cleanup {
+	return Cleanup{cleaners: []func(){f}}
+}
+
+// Add adds a new function to be called on Clean().
+func (c *Cleanup) Add(f func()) {
+	c.cleaners = append(c.cleaners, f)
+}
+
+// Clean calls all cleanup functions in reverse order.
+func (c *Cleanup) Clean() {
+	clean(c.cleaners)
+	c.cleaners = nil
+}
+
+// Release releases the cleanup from its duties, i.e. cleanup functions are not
+// called after this point. Returns a function that calls all registered
+// functions in case the caller has use for them.
+func (c *Cleanup) Release() func() {
+	old := c.cleaners
+	c.cleaners = nil
+	return func() { clean(old) }
+}
+
+func clean(cleaners []func()) {
+	for i := len(cleaners) - 1; i >= 0; i-- {
+		cleaners[i]()
+	}
+}