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// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// +build darwin dragonfly freebsd linux netbsd openbsd
package storage
import (
"os"
"syscall"
)
type unixFileLock struct {
f *os.File
}
func (fl *unixFileLock) release() error {
if err := setFileLock(fl.f, false, false); err != nil {
return err
}
return fl.f.Close()
}
func newFileLock(path string, readOnly bool) (fl fileLock, err error) {
var flag int
if readOnly {
flag = os.O_RDONLY
} else {
flag = os.O_RDWR
}
f, err := os.OpenFile(path, flag, 0)
if os.IsNotExist(err) {
f, err = os.OpenFile(path, flag|os.O_CREATE, 0644)
}
if err != nil {
return
}
err = setFileLock(f, readOnly, true)
if err != nil {
f.Close()
return
}
fl = &unixFileLock{f: f}
return
}
func setFileLock(f *os.File, readOnly, lock bool) error {
how := syscall.LOCK_UN
if lock {
if readOnly {
how = syscall.LOCK_SH
} else {
how = syscall.LOCK_EX
}
}
return syscall.Flock(int(f.Fd()), how|syscall.LOCK_NB)
}
func rename(oldpath, newpath string) error {
return os.Rename(oldpath, newpath)
}
func isErrInvalid(err error) bool {
if err == os.ErrInvalid {
return true
}
// Go < 1.8
if syserr, ok := err.(*os.SyscallError); ok && syserr.Err == syscall.EINVAL {
return true
}
// Go >= 1.8 returns *os.PathError instead
if patherr, ok := err.(*os.PathError); ok && patherr.Err == syscall.EINVAL {
return true
}
return false
}
func syncDir(name string) error {
// As per fsync manpage, Linux seems to expect fsync on directory, however
// some system don't support this, so we will ignore syscall.EINVAL.
//
// From fsync(2):
// Calling fsync() does not necessarily ensure that the entry in the
// directory containing the file has also reached disk. For that an
// explicit fsync() on a file descriptor for the directory is also needed.
f, err := os.Open(name)
if err != nil {
return err
}
defer f.Close()
if err := f.Sync(); err != nil && !isErrInvalid(err) {
return err
}
return nil
}
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