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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build windows
package filelock
import (
"internal/syscall/windows"
"os"
"syscall"
)
type lockType uint32
const (
readLock lockType = 0
writeLock lockType = windows.LOCKFILE_EXCLUSIVE_LOCK
)
const (
reserved = 0
allBytes = ^uint32(0)
)
func lock(f File, lt lockType) error {
// Per https://golang.org/issue/19098, “Programs currently expect the Fd
// method to return a handle that uses ordinary synchronous I/O.”
// However, LockFileEx still requires an OVERLAPPED structure,
// which contains the file offset of the beginning of the lock range.
// We want to lock the entire file, so we leave the offset as zero.
ol := new(syscall.Overlapped)
err := windows.LockFileEx(syscall.Handle(f.Fd()), uint32(lt), reserved, allBytes, allBytes, ol)
if err != nil {
return &os.PathError{
Op: lt.String(),
Path: f.Name(),
Err: err,
}
}
return nil
}
func unlock(f File) error {
ol := new(syscall.Overlapped)
err := windows.UnlockFileEx(syscall.Handle(f.Fd()), reserved, allBytes, allBytes, ol)
if err != nil {
return &os.PathError{
Op: "Unlock",
Path: f.Name(),
Err: err,
}
}
return nil
}
func isNotSupported(err error) bool {
switch err {
case windows.ERROR_NOT_SUPPORTED, windows.ERROR_CALL_NOT_IMPLEMENTED, ErrNotSupported:
return true
default:
return false
}
}
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