require 'fileutils'
require 'puppet/util/lockfile'

class Puppet::Util::Pidlock

  def initialize(lockfile)
    @lockfile = Puppet::Util::Lockfile.new(lockfile)
  end

  def locked?
    clear_if_stale
    @lockfile.locked?
  end

  def mine?
    Process.pid == lock_pid
  end

  def lock
    return mine? if locked?

    @lockfile.lock(Process.pid)
  end

  def unlock
    if mine?
      return @lockfile.unlock
    else
      false
    end
  end

  def lock_pid
    pid = @lockfile.lock_data
    begin
      Integer(pid)
    rescue ArgumentError, TypeError
      nil
    end
  end

  def file_path
    @lockfile.file_path
  end

  private

  def ps_argument_for_current_kernel
    case Puppet.runtime[:facter].value(:kernel)
      when "Linux"
        "-eq"
      when "AIX"
        "-T"
      else
        "-p"
    end
  end

  def clear_if_stale
    pid = lock_pid
    return @lockfile.unlock if pid == nil
    return if Process.pid == pid

    errors = [Errno::ESRCH]
    # Win32::Process now throws SystemCallError. Since this could be
    # defined anywhere, only add when on Windows.
    errors << SystemCallError if Puppet::Util::Platform.windows?

    begin
      Process.kill(0, pid)
    rescue *errors
      return @lockfile.unlock
    end

    # Ensure the process associated with this pid is our process. If
    # not, we can unlock the lockfile. CLI arguments used for identifying
    # on POSIX depend on the os and sometimes even version.
    if Puppet.features.posix?
      ps_argument = ps_argument_for_current_kernel

      # Check, obtain and use the right ps argument
      begin
        procname = Puppet::Util::Execution.execute(["ps", ps_argument, pid, "-o", "comm="]).strip
      rescue Puppet::ExecutionFailure
        ps_argument = "-p"
        procname = Puppet::Util::Execution.execute(["ps", ps_argument, pid, "-o", "comm="]).strip
      end

      args = Puppet::Util::Execution.execute(["ps", ps_argument, pid, "-o", "args="]).strip
      @lockfile.unlock unless procname =~ /ruby/ && args =~ /puppet/ || procname =~ /puppet(-.*)?$/
    elsif Puppet.features.microsoft_windows?
      # On Windows, we're checking if the filesystem path name of the running
      # process is our vendored ruby:
      begin
        exe_path = Puppet::Util::Windows::Process::get_process_image_name_by_pid(pid)
        @lockfile.unlock unless exe_path =~ /\\bin\\ruby.exe$/
      rescue Puppet::Util::Windows::Error => e
        Puppet.debug("Failed to read pidfile #{file_path}: #{e.message}")
      end
    end
  end
end