//go:build windows

package state

import (
	"os"
	"runtime"
	"syscall"
	"unsafe"
)

var lockFileEx = syscall.NewLazyDLL("kernel32.dll").NewProc("LockFileEx")

func lockExclusive(f *os.File) error {
	var overlapped syscall.Overlapped
	// LOCKFILE_FAIL_IMMEDIATELY | LOCKFILE_EXCLUSIVE_LOCK, first byte only.
	ok, _, err := lockFileEx.Call(f.Fd(), 3, 0, 1, 0, uintptr(unsafe.Pointer(&overlapped)))
	runtime.KeepAlive(f)
	if ok != 0 {
		return nil
	}
	if err == syscall.Errno(33) {
		return ErrBusy
	}
	return err
}

// Windows is a development platform. File.Sync is used, but Go does not provide
// a portable directory fsync here. Do not claim Windows power-loss durability.
func syncDirectory(*os.Root) error { return nil }