metanorma/vectory

require "timeout"

module Vectory
  module Capture
    class << self
      # rubocop:disable all
      #
      # Originally from https://gist.github.com/pasela/9392115
      #
      # Capture the standard output and the standard error of a command.
      # Almost same as Open3.capture3 method except for timeout handling and return value.
      # See Open3.capture3.
      #
      #   result = capture3_with_timeout([env,] cmd... [, opts])
      #
      # The arguments env, cmd and opts are passed to Process.spawn except
      # opts[:stdin_data], opts[:binmode], opts[:timeout], opts[:signal]
      # and opts[:kill_after].  See Process.spawn.
      #
      # If opts[:stdin_data] is specified, it is sent to the command's standard input.
      #
      # If opts[:binmode] is true, internal pipes are set to binary mode.
      #
      # If opts[:timeout] is specified, SIGTERM is sent to the command after specified seconds.
      #
      # If opts[:signal] is specified, it is used instead of SIGTERM on timeout.
      #
      # If opts[:kill_after] is specified, also send a SIGKILL after specified seconds.
      # it is only sent if the command is still running after the initial signal was sent.
      #
      # The return value is a Hash as shown below.
      #
      #   {
      #     :pid     => PID of the command,
      #     :status  => Process::Status of the command,
      #     :stdout  => the standard output of the command,
      #     :stderr  => the standard error of the command,
      #     :timeout => whether the command was timed out,
      #   }
      def with_timeout(*cmd)
        spawn_opts = Hash === cmd.last ? cmd.pop.dup : {}
        opts = {
          :stdin_data => spawn_opts.delete(:stdin_data) || "",
          :binmode    => spawn_opts.delete(:binmode) || false,
          :timeout    => spawn_opts.delete(:timeout),
          :signal     => spawn_opts.delete(:signal) || :TERM,
          :kill_after => spawn_opts.delete(:kill_after),
        }

        in_r,  in_w  = IO.pipe
        out_r, out_w = IO.pipe
        err_r, err_w = IO.pipe
        in_w.sync = true

        if opts[:binmode]
          in_w.binmode
          out_r.binmode
          err_r.binmode
        end

        spawn_opts[:in]  = in_r
        spawn_opts[:out] = out_w
        spawn_opts[:err] = err_w

        result = {
          :pid     => nil,
          :status  => nil,
          :stdout  => nil,
          :stderr  => nil,
          :timeout => false,
        }

        out_reader = nil
        err_reader = nil
        wait_thr = nil

        begin
          Timeout.timeout(opts[:timeout]) do
            result[:pid] = spawn(*cmd, spawn_opts)
            wait_thr = Process.detach(result[:pid])
            in_r.close
            out_w.close
            err_w.close

            out_reader = Thread.new { out_r.read }
            err_reader = Thread.new { err_r.read }

            in_w.write opts[:stdin_data]
            in_w.close

            result[:status] = wait_thr.value
          end
        rescue Timeout::Error
          result[:timeout] = true
          pid = spawn_opts[:pgroup] ? -result[:pid] : result[:pid]
          Process.kill(opts[:signal], pid)
          if opts[:kill_after]
            unless wait_thr.join(opts[:kill_after])
              Process.kill(:KILL, pid)
            end
          end
        ensure
          result[:status] = wait_thr.value if wait_thr
          result[:stdout] = out_reader.value if out_reader
          result[:stderr] = err_reader.value if err_reader
          out_r.close unless out_r.closed?
          err_r.close unless err_r.closed?
        end

        result
      end
      # rubocop:enable all
    end
  end
end