Official Go implementation of the Ethereum protocol
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go-ethereum/vendor/github.com/prometheus/tsdb/fileutil/flock_unix.go

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1.2 KiB

// Copyright 2016 The Prometheus 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.
// +build darwin dragonfly freebsd linux netbsd openbsd
package fileutil
import (
"os"
"syscall"
)
type unixLock struct {
f *os.File
}
func (l *unixLock) Release() error {
if err := l.set(false); err != nil {
return err
}
return l.f.Close()
}
func (l *unixLock) set(lock bool) error {
how := syscall.LOCK_UN
if lock {
how = syscall.LOCK_EX
}
return syscall.Flock(int(l.f.Fd()), how|syscall.LOCK_NB)
}
func newLock(fileName string) (Releaser, error) {
f, err := os.OpenFile(fileName, os.O_RDWR|os.O_CREATE, 0644)
if err != nil {
return nil, err
}
l := &unixLock{f}
err = l.set(true)
if err != nil {
f.Close()
return nil, err
}
return l, nil
}