github.com/enetx/g@v1.0.80/internal/filelock/filelock_windows.go (about) 1 // Copyright 2018 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 //go:build windows 6 7 package filelock 8 9 import ( 10 "io/fs" 11 "syscall" 12 13 "github.com/enetx/g/internal/filelock/syscall/windows" 14 ) 15 16 type lockType uint32 17 18 const ( 19 readLock lockType = 0 20 writeLock lockType = windows.LOCKFILE_EXCLUSIVE_LOCK 21 ) 22 23 const ( 24 reserved = 0 25 allBytes = ^uint32(0) 26 ) 27 28 func lock(f File, lt lockType) error { 29 // Per https://golang.org/issue/19098, “Programs currently expect the Fd 30 // method to return a handle that uses ordinary synchronous I/O.” 31 // However, LockFileEx still requires an OVERLAPPED structure, 32 // which contains the file offset of the beginning of the lock range. 33 // We want to lock the entire file, so we leave the offset as zero. 34 ol := new(syscall.Overlapped) 35 36 err := windows.LockFileEx(syscall.Handle(f.Fd()), uint32(lt), reserved, allBytes, allBytes, ol) 37 if err != nil { 38 return &fs.PathError{ 39 Op: lt.String(), 40 Path: f.Name(), 41 Err: err, 42 } 43 } 44 return nil 45 } 46 47 func unlock(f File) error { 48 ol := new(syscall.Overlapped) 49 err := windows.UnlockFileEx(syscall.Handle(f.Fd()), reserved, allBytes, allBytes, ol) 50 if err != nil { 51 return &fs.PathError{ 52 Op: "Unlock", 53 Path: f.Name(), 54 Err: err, 55 } 56 } 57 return nil 58 }