52 lines
1.4 KiB
Go
52 lines
1.4 KiB
Go
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// +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"
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"sync"
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"golang.org/x/sys/unix"
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)
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var (
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// lock guards lockfile. Assignment is not atomic.
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lock sync.Mutex
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// os.File has a runtime.Finalizer so the fd will be closed if the struct
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// is garbage collected. Let's hold onto a reference so that doesn't happen.
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lockfile *os.File
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)
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// Acquire acquires a lock on a file for the duration of the process. This method
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// is reentrant.
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func Acquire(path string) error {
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lock.Lock()
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defer lock.Unlock()
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var err error
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if lockfile, err = os.OpenFile(path, os.O_RDWR|os.O_CREATE, 0600); err != nil {
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return err
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}
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defer lockfile.Close()
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opts := unix.Flock_t{Type: unix.F_WRLCK}
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if err := unix.FcntlFlock(lockfile.Fd(), unix.F_SETLKW, &opts); err != nil {
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return err
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}
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return nil
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}
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