//go:build windows

package stack

import (
	"errors"
	"os"

	"golang.org/x/sys/windows"
)

// tryLockFile attempts a non-blocking exclusive lock.
// Returns nil on success, or an error if the lock is held by another process.
func tryLockFile(f *os.File) error {
	ol := new(windows.Overlapped)
	return windows.LockFileEx(
		windows.Handle(f.Fd()),
		windows.LOCKFILE_EXCLUSIVE_LOCK|windows.LOCKFILE_FAIL_IMMEDIATELY,
		0,  // reserved
		1,  // lock 1 byte
		0,  // high word
		ol,
	)
}

// isLockBusy reports whether err indicates the lock is held by another process.
func isLockBusy(err error) bool {
	return errors.Is(err, windows.ERROR_LOCK_VIOLATION)
}

func unlockFile(f *os.File) {
	ol := new(windows.Overlapped)
	_ = windows.UnlockFileEx(
		windows.Handle(f.Fd()),
		0, 1, 0, ol,
	)
}