github.com/insionng/yougam@v0.0.0-20170714101924-2bc18d833463/libraries/syndtr/goleveldb/leveldb/storage/file_storage_unix.go (about)

     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  
     9  package storage
    10  
    11  import (
    12  	"os"
    13  	"syscall"
    14  )
    15  
    16  type unixFileLock struct {
    17  	f *os.File
    18  }
    19  
    20  func (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  
    27  func 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  
    50  func 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  
    62  func rename(oldpath, newpath string) error {
    63  	return os.Rename(oldpath, newpath)
    64  }
    65  
    66  func isErrInvalid(err error) bool {
    67  	if err == os.ErrInvalid {
    68  		return true
    69  	}
    70  	if syserr, ok := err.(*os.SyscallError); ok && syserr.Err == syscall.EINVAL {
    71  		return true
    72  	}
    73  	return false
    74  }
    75  
    76  func syncDir(name string) error {
    77  	f, err := os.Open(name)
    78  	if err != nil {
    79  		return err
    80  	}
    81  	defer f.Close()
    82  	if err := f.Sync(); err != nil && !isErrInvalid(err) {
    83  		return err
    84  	}
    85  	return nil
    86  }