# stolen directly from Open3::open3.rb!
#
# open4.rb: Spawn a program like popen, but with stderr, and pid, too. You might
# also want to use this if you want to bypass the shell. (By passing multiple
# args, which IO#popen does not allow)
#
# Usage:
#       require "open4"
#
#      pid, stdin, stdout, stderr = Open4.popen4('nroff -man')
#  or
#       include Open4
#      pid, stdin, stdout, stderr = popen4('nroff -man')

  module Open4
#--{{{
  #
  # [ pid, stdin, stdout, stderr ] = popen4 command
  #
    def popen4(*cmd)
#--{{{
      pw = IO::pipe   # pipe[0] for read, pipe[1] for write
      pr = IO::pipe
      pe = IO::pipe

      verbose = $VERBOSE
      begin
        $VERBOSE = nil # shut up warning about forking in threads, world writable
                       # dirs, etc
        cid =
          fork{
            # child
            pw[1].close
            STDIN.reopen(pw[0])
            pw[0].close

            pr[0].close
            STDOUT.reopen(pr[1])
            pr[1].close

            pe[0].close
            STDERR.reopen(pe[1])
            pe[1].close

            STDOUT.sync = true
            STDERR.sync = true

            exec(*cmd)
          }
      ensure
        $VERBOSE = verbose
      end

      pw[0].close
      pr[1].close
      pe[1].close
      pi = [pw[1], pr[0], pe[0]]
      pw[1].sync = true
      if defined? yield
        begin
          yield(cid, *pi)
          return(Process::waitpid2(cid).last)
        ensure
          pi.each{|p| p.close unless p.closed?}
        end
      end
      [cid, pw[1], pr[0], pe[0]]
#--}}}
    end
    alias open4 popen4
    module_function :popen4
    module_function :open4
#--}}}
  end

if $0 == __FILE__
  status = Open4::popen4('sh'){|cid,i,o,e|i.puts 'echo 42';i.close; puts o.read;}
  p [status]
  p status.exitstatus
  p status == 0
end