brew/Library/Homebrew/cask/lib/hbc/utils/file.rb

module Hbc
  module Utils
    module_function

    def file_locked?(file)
      unlocked = File.open(file).flock(File::LOCK_EX | File::LOCK_NB)
      # revert lock if file was unlocked before check
      File.open(file).flock(File::LOCK_UN) if unlocked
      !unlocked
    rescue
      true
    end
  end
end