rollback: use 237 wal pkg

third_party/forked/etcd237/pkg/fileutil/lock_unix.go

@@ -0,0 +1,65 @@
+// Copyright 2015 CoreOS, Inc.
+//
+// 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 !windows,!plan9,!solaris
+
+package fileutil
+
+import (
+	"errors"
+	"os"
+	"syscall"
+)
+
+var (
+	ErrLocked = errors.New("file already locked")
+)
+
+type lock struct {
+	fd   int
+	file *os.File
+}
+
+func (l *lock) Name() string {
+	return l.file.Name()
+}
+
+func (l *lock) TryLock() error {
+	err := syscall.Flock(l.fd, syscall.LOCK_EX|syscall.LOCK_NB)
+	if err != nil && err == syscall.EWOULDBLOCK {
+		return ErrLocked
+	}
+	return err
+}
+
+func (l *lock) Lock() error {
+	return syscall.Flock(l.fd, syscall.LOCK_EX)
+}
+
+func (l *lock) Unlock() error {
+	return syscall.Flock(l.fd, syscall.LOCK_UN)
+}
+
+func (l *lock) Destroy() error {
+	return l.file.Close()
+}
+
+func NewLock(file string) (Lock, error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	l := &lock{int(f.Fd()), f}
+	return l, nil
+}