mirror of https://github.com/k3s-io/k3s
103 lines
2.6 KiB
Go
103 lines
2.6 KiB
Go
// Copyright 2013 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.
|
|
|
|
package filemutex
|
|
|
|
import (
|
|
"syscall"
|
|
"unsafe"
|
|
)
|
|
|
|
var (
|
|
modkernel32 = syscall.NewLazyDLL("kernel32.dll")
|
|
procLockFileEx = modkernel32.NewProc("LockFileEx")
|
|
procUnlockFileEx = modkernel32.NewProc("UnlockFileEx")
|
|
)
|
|
|
|
const (
|
|
lockfileExclusiveLock = 2
|
|
)
|
|
|
|
func lockFileEx(h syscall.Handle, flags, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
|
|
r1, _, e1 := syscall.Syscall6(procLockFileEx.Addr(), 6, uintptr(h), uintptr(flags), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)))
|
|
if r1 == 0 {
|
|
if e1 != 0 {
|
|
err = error(e1)
|
|
} else {
|
|
err = syscall.EINVAL
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
func unlockFileEx(h syscall.Handle, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
|
|
r1, _, e1 := syscall.Syscall6(procUnlockFileEx.Addr(), 5, uintptr(h), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)), 0)
|
|
if r1 == 0 {
|
|
if e1 != 0 {
|
|
err = error(e1)
|
|
} else {
|
|
err = syscall.EINVAL
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
// FileMutex is similar to sync.RWMutex, but also synchronizes across processes.
|
|
// This implementation is based on flock syscall.
|
|
type FileMutex struct {
|
|
fd syscall.Handle
|
|
}
|
|
|
|
func New(filename string) (*FileMutex, error) {
|
|
fd, err := syscall.CreateFile(&(syscall.StringToUTF16(filename)[0]), syscall.GENERIC_READ|syscall.GENERIC_WRITE,
|
|
syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE, nil, syscall.OPEN_ALWAYS, syscall.FILE_ATTRIBUTE_NORMAL, 0)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return &FileMutex{fd: fd}, nil
|
|
}
|
|
|
|
func (m *FileMutex) Lock() error {
|
|
var ol syscall.Overlapped
|
|
if err := lockFileEx(m.fd, lockfileExclusiveLock, 0, 1, 0, &ol); err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (m *FileMutex) Unlock() error {
|
|
var ol syscall.Overlapped
|
|
if err := unlockFileEx(m.fd, 0, 1, 0, &ol); err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (m *FileMutex) RLock() error {
|
|
var ol syscall.Overlapped
|
|
if err := lockFileEx(m.fd, 0, 0, 1, 0, &ol); err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (m *FileMutex) RUnlock() error {
|
|
var ol syscall.Overlapped
|
|
if err := unlockFileEx(m.fd, 0, 1, 0, &ol); err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Close does an Unlock() combined with closing and unlinking the associated
|
|
// lock file. You should create a New() FileMutex for every Lock() attempt if
|
|
// using Close().
|
|
func (m *FileMutex) Close() error {
|
|
var ol syscall.Overlapped
|
|
if err := unlockFileEx(m.fd, 0, 1, 0, &ol); err != nil {
|
|
return err
|
|
}
|
|
return syscall.Close(m.fd)
|
|
}
|