mirror of https://github.com/k3s-io/k3s.git
63 lines
1.8 KiB
Go
63 lines
1.8 KiB
Go
//go:build linux || darwin || freebsd || openbsd || netbsd || dragonfly
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/*
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Copyright 2016 The Kubernetes Authors.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package flock
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import (
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"os/exec"
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"strings"
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"golang.org/x/sys/unix"
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)
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// Acquire creates an exclusive lock on a file for the duration of the process, or until Release(d).
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// This method is reentrant.
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func Acquire(path string) (int, error) {
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lock, err := unix.Open(path, unix.O_CREAT|unix.O_RDWR|unix.O_CLOEXEC, 0600)
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if err != nil {
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return -1, err
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}
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return lock, unix.Flock(lock, unix.LOCK_EX)
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}
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// AcquireShared creates a shared lock on a file for the duration of the process, or until Release(d).
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// This method is reentrant.
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func AcquireShared(path string) (int, error) {
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lock, err := unix.Open(path, unix.O_CREAT|unix.O_RDWR, 0600)
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if err != nil {
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return -1, err
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}
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return lock, unix.Flock(lock, unix.LOCK_SH)
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}
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// Release removes an existing lock held by this process.
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func Release(lock int) error {
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return unix.Flock(lock, unix.LOCK_UN)
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}
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// CheckLock checks whether any process is using the lock
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func CheckLock(path string) bool {
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lockByte, _ := exec.Command("lsof", "-w", "-F", "ln", path).Output()
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locks := string(lockByte)
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if locks == "" {
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return false
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}
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readWriteLock := strings.Split(locks, "\n")[2]
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return readWriteLock == "lR" || readWriteLock == "lW"
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}
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