109 lines
2.2 KiB
Go
109 lines
2.2 KiB
Go
// +build windows
|
|
|
|
package clistate
|
|
|
|
import (
|
|
"math"
|
|
"syscall"
|
|
"unsafe"
|
|
)
|
|
|
|
var (
|
|
modkernel32 = syscall.NewLazyDLL("kernel32.dll")
|
|
procLockFileEx = modkernel32.NewProc("LockFileEx")
|
|
procCreateEventW = modkernel32.NewProc("CreateEventW")
|
|
)
|
|
|
|
const (
|
|
// dwFlags defined for LockFileEx
|
|
// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx
|
|
_LOCKFILE_FAIL_IMMEDIATELY = 1
|
|
_LOCKFILE_EXCLUSIVE_LOCK = 2
|
|
)
|
|
|
|
func (s *LocalState) lock() error {
|
|
// even though we're failing immediately, an overlapped event structure is
|
|
// required
|
|
ol, err := newOverlapped()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer syscall.CloseHandle(ol.HEvent)
|
|
|
|
return lockFileEx(
|
|
syscall.Handle(s.stateFileOut.Fd()),
|
|
_LOCKFILE_EXCLUSIVE_LOCK|_LOCKFILE_FAIL_IMMEDIATELY,
|
|
0, // reserved
|
|
0, // bytes low
|
|
math.MaxUint32, // bytes high
|
|
ol,
|
|
)
|
|
}
|
|
|
|
func (s *LocalState) unlock() error {
|
|
// the file is closed in Unlock
|
|
return nil
|
|
}
|
|
|
|
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
|
|
}
|
|
|
|
// newOverlapped creates a structure used to track asynchronous
|
|
// I/O requests that have been issued.
|
|
func newOverlapped() (*syscall.Overlapped, error) {
|
|
event, err := createEvent(nil, true, false, nil)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return &syscall.Overlapped{HEvent: event}, nil
|
|
}
|
|
|
|
func createEvent(sa *syscall.SecurityAttributes, manualReset bool, initialState bool, name *uint16) (handle syscall.Handle, err error) {
|
|
var _p0 uint32
|
|
if manualReset {
|
|
_p0 = 1
|
|
}
|
|
var _p1 uint32
|
|
if initialState {
|
|
_p1 = 1
|
|
}
|
|
|
|
r0, _, e1 := syscall.Syscall6(
|
|
procCreateEventW.Addr(),
|
|
4,
|
|
uintptr(unsafe.Pointer(sa)),
|
|
uintptr(_p0),
|
|
uintptr(_p1),
|
|
uintptr(unsafe.Pointer(name)),
|
|
0,
|
|
0,
|
|
)
|
|
handle = syscall.Handle(r0)
|
|
if handle == syscall.InvalidHandle {
|
|
if e1 != 0 {
|
|
err = error(e1)
|
|
} else {
|
|
err = syscall.EINVAL
|
|
}
|
|
}
|
|
return
|
|
}
|