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/sighandling/sighandling.go

@@ -0,0 +1,113 @@
+// Copyright 2018 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 sighandling contains helpers for handling signals to applications.
+package sighandling
+
+import (
+	"os"
+	"os/signal"
+	"reflect"
+
+	"github.com/sagernet/gvisor/pkg/abi/linux"
+	"golang.org/x/sys/unix"
+)
+
+// numSignals is the number of normal (non-realtime) signals on Linux.
+const numSignals = 32
+
+// handleSignals listens for incoming signals and calls the given handler
+// function.
+//
+// It stops when the stop channel is closed. The done channel is closed once it
+// will no longer deliver signals to k.
+func handleSignals(sigchans []chan os.Signal, handler func(linux.Signal), stop, done chan struct{}) {
+	// Build a select case.
+	sc := []reflect.SelectCase{{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(stop)}}
+	for _, sigchan := range sigchans {
+		sc = append(sc, reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(sigchan)})
+	}
+
+	for {
+		// Wait for a notification.
+		index, _, ok := reflect.Select(sc)
+
+		// Was it the stop channel?
+		if index == 0 {
+			if !ok {
+				// Stop forwarding and notify that it's done.
+				close(done)
+				return
+			}
+			continue
+		}
+
+		// How about a different close?
+		if !ok {
+			panic("signal channel closed unexpectedly")
+		}
+
+		// Otherwise, it was a signal on channel N. Index 0 represents the stop
+		// channel, so index N represents the channel for signal N.
+		handler(linux.Signal(index))
+	}
+}
+
+// StartSignalForwarding ensures that synchronous signals are passed to the
+// given handler function and returns a callback that stops signal delivery.
+//
+// Note that this function permanently takes over signal handling. After the
+// stop callback, signals revert to the default Go runtime behavior, which
+// cannot be overridden with external calls to signal.Notify.
+func StartSignalForwarding(handler func(linux.Signal)) func() {
+	stop := make(chan struct{})
+	done := make(chan struct{})
+
+	// Register individual channels. One channel per standard signal is
+	// required as os.Notify() is non-blocking and may drop signals. To avoid
+	// this, standard signals have to be queued separately. Channel size 1 is
+	// enough for standard signals as their semantics allow de-duplication.
+	//
+	// External real-time signals are not supported. We rely on the go-runtime
+	// for their handling.
+	//
+	// We do not forward some signals that are likely induced by the behavior
+	// of the forwarding process.
+	var sigchans []chan os.Signal
+	for sig := 1; sig <= numSignals+1; sig++ {
+		sigchan := make(chan os.Signal, 1)
+		sigchans = append(sigchans, sigchan)
+
+		// SIGURG is used by Go's runtime scheduler.
+		if sig == int(linux.SIGURG) {
+			continue
+		}
+		// SIGPIPE is received when sending to disconnected host pipes/sockets.
+		if sig == int(linux.SIGPIPE) {
+			continue
+		}
+		// SIGCHLD is received when a child of the forwarding process exits.
+		if sig == int(linux.SIGCHLD) {
+			continue
+		}
+		signal.Notify(sigchan, unix.Signal(sig))
+	}
+	// Start up our listener.
+	go handleSignals(sigchans, handler, stop, done) // S/R-SAFE: synchronized by Kernel.extMu.
+
+	return func() {
+		close(stop)
+		<-done
+	}
+}

pkg/sighandling/sighandling_darwin.go

@@ -0,0 +1,40 @@
+// Copyright 2021 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 darwin
+// +build darwin
+
+package sighandling
+
+import (
+	"errors"
+
+	"golang.org/x/sys/unix"
+)
+
+// IgnoreChildStop sets the SA_NOCLDSTOP flag, causing child processes to not
+// generate SIGCHLD when they stop.
+func IgnoreChildStop() error {
+	return errors.New("IgnoreChildStop not supported on Darwin")
+}
+
+// ReplaceSignalHandler replaces the existing signal handler for the provided
+// signal with the function pointer at `handler`. This bypasses the Go runtime
+// signal handlers, and should only be used for low-level signal handlers where
+// use of signal.Notify is not appropriate.
+//
+// It stores the value of the previously set handler in previous.
+func ReplaceSignalHandler(sig unix.Signal, handler uintptr, previous *uintptr) error {
+	return errors.New("ReplaceSignalHandler not supported on Darwin")
+}

pkg/sighandling/sighandling_linux_unsafe.go

@@ -0,0 +1,103 @@
+// Copyright 2018 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 sighandling
+
+import (
+	"fmt"
+	"os"
+	"unsafe"
+
+	"github.com/sagernet/gvisor/pkg/abi/linux"
+	"golang.org/x/sys/unix"
+)
+
+// IgnoreChildStop sets the SA_NOCLDSTOP flag, causing child processes to not
+// generate SIGCHLD when they stop.
+func IgnoreChildStop() error {
+	var sa linux.SigAction
+
+	// Get the existing signal handler information, and set the flag.
+	if _, _, e := unix.RawSyscall6(unix.SYS_RT_SIGACTION, uintptr(unix.SIGCHLD), 0, uintptr(unsafe.Pointer(&sa)), linux.SignalSetSize, 0, 0); e != 0 {
+		return e
+	}
+	sa.Flags |= linux.SA_NOCLDSTOP
+	if _, _, e := unix.RawSyscall6(unix.SYS_RT_SIGACTION, uintptr(unix.SIGCHLD), uintptr(unsafe.Pointer(&sa)), 0, linux.SignalSetSize, 0, 0); e != 0 {
+		return e
+	}
+
+	return nil
+}
+
+// ReplaceSignalHandler replaces the existing signal handler for the provided
+// signal with the function pointer at `handler`. This bypasses the Go runtime
+// signal handlers, and should only be used for low-level signal handlers where
+// use of signal.Notify is not appropriate.
+//
+// It stores the value of the previously set handler in previous.
+func ReplaceSignalHandler(sig unix.Signal, handler uintptr, previous *uintptr) error {
+	var sa linux.SigAction
+	const maskLen = 8
+
+	// Get the existing signal handler information, and save the current
+	// handler. Once we replace it, we will use this pointer to fall back to
+	// it when we receive other signals.
+	if _, _, e := unix.RawSyscall6(unix.SYS_RT_SIGACTION, uintptr(sig), 0, uintptr(unsafe.Pointer(&sa)), maskLen, 0, 0); e != 0 {
+		return e
+	}
+
+	// Fail if there isn't a previous handler.
+	if sa.Handler == 0 {
+		return fmt.Errorf("previous handler for signal %x isn't set", sig)
+	}
+
+	*previous = uintptr(sa.Handler)
+
+	// Install our own handler.
+	sa.Handler = uint64(handler)
+	if _, _, e := unix.RawSyscall6(unix.SYS_RT_SIGACTION, uintptr(sig), uintptr(unsafe.Pointer(&sa)), 0, maskLen, 0, 0); e != 0 {
+		return e
+	}
+
+	return nil
+}
+
+// KillItself sends SIGKILL to the current process, bypassing the init process
+// restriction.
+//
+// The standard `kill(getpid(), SIGKILL)` syscall doesn't work when the current
+// process is the init process within its PID namespace. This is a "known"
+// Linux feature.
+//
+// This function uses the rt_tgqueueinfo syscall to send a "kernel-generated"
+// SIGKILL.
+func KillItself() error {
+	pid := os.Getpid()
+	tid, _, _ := unix.RawSyscall(unix.SYS_GETTID, 0, 0, 0)
+	info := linux.SignalInfo{Code: linux.SI_KERNEL}
+	// The current thread can send a fake kernel siginfo to itself.
+	if _, _, e := unix.RawSyscall6(
+		unix.SYS_RT_TGSIGQUEUEINFO,
+		uintptr(pid), uintptr(tid),
+		uintptr(linux.SIGKILL),
+		uintptr(unsafe.Pointer(&info)),
+		0, 0,
+	); e != 0 {
+		return e
+	}
+	panic("unreachable")
+}

pkg/sighandling/sighandling_linux_unsafe_state_autogen.go

@@ -0,0 +1,6 @@
+// automatically generated by stateify.
+
+//go:build linux
+// +build linux
+
+package sighandling

pkg/sighandling/sighandling_state_autogen.go

@@ -0,0 +1,6 @@
+// automatically generated by stateify.
+
+//go:build darwin
+// +build darwin
+
+package sighandling