1// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com> 2// All rights reserved. 3// 4// Use of this source code is governed by a BSD-style license that can be 5// found in the LICENSE file. 6 7// +build darwin dragonfly freebsd linux netbsd openbsd 8 9package storage 10 11import ( 12 "os" 13 "syscall" 14) 15 16type unixFileLock struct { 17 f *os.File 18} 19 20func (fl *unixFileLock) release() error { 21 if err := setFileLock(fl.f, false, false); err != nil { 22 return err 23 } 24 return fl.f.Close() 25} 26 27func newFileLock(path string, readOnly bool) (fl fileLock, err error) { 28 var flag int 29 if readOnly { 30 flag = os.O_RDONLY 31 } else { 32 flag = os.O_RDWR 33 } 34 f, err := os.OpenFile(path, flag, 0) 35 if os.IsNotExist(err) { 36 f, err = os.OpenFile(path, flag|os.O_CREATE, 0644) 37 } 38 if err != nil { 39 return 40 } 41 err = setFileLock(f, readOnly, true) 42 if err != nil { 43 f.Close() 44 return 45 } 46 fl = &unixFileLock{f: f} 47 return 48} 49 50func setFileLock(f *os.File, readOnly, lock bool) error { 51 how := syscall.LOCK_UN 52 if lock { 53 if readOnly { 54 how = syscall.LOCK_SH 55 } else { 56 how = syscall.LOCK_EX 57 } 58 } 59 return syscall.Flock(int(f.Fd()), how|syscall.LOCK_NB) 60} 61 62func rename(oldpath, newpath string) error { 63 return os.Rename(oldpath, newpath) 64} 65 66func isErrInvalid(err error) bool { 67 if err == os.ErrInvalid { 68 return true 69 } 70 // Go < 1.8 71 if syserr, ok := err.(*os.SyscallError); ok && syserr.Err == syscall.EINVAL { 72 return true 73 } 74 // Go >= 1.8 returns *os.PathError instead 75 if patherr, ok := err.(*os.PathError); ok && patherr.Err == syscall.EINVAL { 76 return true 77 } 78 return false 79} 80 81func syncDir(name string) error { 82 // As per fsync manpage, Linux seems to expect fsync on directory, however 83 // some system don't support this, so we will ignore syscall.EINVAL. 84 // 85 // From fsync(2): 86 // Calling fsync() does not necessarily ensure that the entry in the 87 // directory containing the file has also reached disk. For that an 88 // explicit fsync() on a file descriptor for the directory is also needed. 89 f, err := os.Open(name) 90 if err != nil { 91 return err 92 } 93 defer f.Close() 94 if err := f.Sync(); err != nil && !isErrInvalid(err) { 95 return err 96 } 97 return nil 98} 99