//go:build !windows

package main

import (
	"fmt"
	"os"
	"syscall"
)

func acquireLock(path string) (func(), error) {
	file, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o600)
	if err != nil {
		return nil, err
	}
	if err := syscall.Flock(int(file.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
		_ = file.Close()
		return nil, fmt.Errorf("another test harness process holds %s: %w", path, err)
	}
	return func() {
		_ = syscall.Flock(int(file.Fd()), syscall.LOCK_UN)
		_ = file.Close()
	}, nil
}