mirror of
https://github.com/SagerNet/sing-tun.git
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52 lines
1.7 KiB
Go
52 lines
1.7 KiB
Go
// Copyright 2022 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//go:build linux
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// +build linux
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// Package stopfd provides an type that can be used to signal the stop of a dispatcher.
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package stopfd
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import (
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"fmt"
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"golang.org/x/sys/unix"
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)
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// StopFD is an eventfd used to signal the stop of a dispatcher.
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type StopFD struct {
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EFD int
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}
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// New returns a new, initialized StopFD.
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func New() (StopFD, error) {
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efd, err := unix.Eventfd(0, unix.EFD_NONBLOCK)
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if err != nil {
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return StopFD{EFD: -1}, fmt.Errorf("failed to create eventfd: %w", err)
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}
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return StopFD{EFD: efd}, nil
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}
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// Stop writes to the eventfd and notifies the dispatcher to stop. It does not
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// block.
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func (sf *StopFD) Stop() {
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increment := []byte{1, 0, 0, 0, 0, 0, 0, 0}
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if n, err := unix.Write(sf.EFD, increment); n != len(increment) || err != nil {
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// There are two possible errors documented in eventfd(2) for writing:
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// 1. We are writing 8 bytes and not 0xffffffffffffff, thus no EINVAL.
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// 2. stop is only supposed to be called once, it can't reach the limit,
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// thus no EAGAIN.
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panic(fmt.Sprintf("write(EFD) = (%d, %s), want (%d, nil)", n, err, len(increment)))
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}
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}
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