/Chapter 6/MockChat/lib/ruby/1.8/open3.rb

#

# = open3.rb: Popen, but with stderr, too

#

# Author:: Yukihiro Matsumoto

# Documentation:: Konrad Meyer

#

# Open3 gives you access to stdin, stdout, and stderr when running other

# programs.

#



#

# Open3 grants you access to stdin, stdout, and stderr when running another

# program. Example:

#

#   require "open3"

#   include Open3

#   

#   stdin, stdout, stderr = popen3('nroff -man')

#

# Open3.popen3 can also take a block which will receive stdin, stdout and

# stderr as parameters.  This ensures stdin, stdout and stderr are closed

# once the block exits. Example:

#

#   require "open3"

#

#   Open3.popen3('nroff -man') { |stdin, stdout, stderr| ... }

#



module Open3

  # 

  # Open stdin, stdout, and stderr streams and start external executable.

  # Non-block form:

  #   

  #   require 'open3'

  #

  #   [stdin, stdout, stderr] = Open3.popen3(cmd)

  #

  # Block form:

  #

  #   require 'open3'

  #

  #   Open3.popen3(cmd) { |stdin, stdout, stderr| ... }

  #

  # The parameter +cmd+ is passed directly to Kernel#exec.

  #

  def popen3(*cmd)

    pw = IO::pipe   # pipe[0] for read, pipe[1] for write

    pr = IO::pipe

    pe = IO::pipe



    pid = fork{

      # child

      fork{

	# grandchild

	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



	exec(*cmd)

      }

      exit!(0)

    }



    pw[0].close

    pr[1].close

    pe[1].close

    Process.waitpid(pid)

    pi = [pw[1], pr[0], pe[0]]

    pw[1].sync = true

    if defined? yield

      begin

	return yield(*pi)

      ensure

	pi.each{|p| p.close unless p.closed?}

      end

    end

    pi

  end

  module_function :popen3

end



if $0 == __FILE__

  a = Open3.popen3("nroff -man")

  Thread.start do

    while line = gets

      a[0].print line

    end

    a[0].close

  end

  while line = a[1].gets

    print ":", line

  end

end