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#--
# =============================================================================
# Copyright (c) 2004,2005 Jamis Buck (jamis@37signals.com)
# All rights reserved.
#
# This source file is distributed as part of the Net::SSH Secure Shell Client
# library for Ruby. This file (and the library as a whole) may be used only as
# allowed by either the BSD license, or the Ruby license (or, by association
# with the Ruby license, the GPL). See the "doc" subdirectory of the Net::SSH
# distribution for the texts of these licenses.
# -----------------------------------------------------------------------------
# net-ssh website : http://net-ssh.rubyforge.org
# project website: http://rubyforge.org/projects/net-ssh
# =============================================================================
#++
require 'net/ssh/errors'
module Net
module SSH
module Service
module Process
# Represents a process executing on the remote machine. It also provides
# a simple interface for interacting with such a remote process.
#
# It may be used in either of two ways. The first allows multiple
# processes to be invoked on the remote machine and run in parallel
# over the same session. Because of this, it is a bit complicated to
# set up:
#
# require 'net/ssh'
#
# Net::SSH.start( 'host', 'user', 'passwd' ) do |session|
# process = session.process.open( "bc" )
# dialog = [ "5+5", "7*12", "1+2*5/(7+3)" ]
#
# process.on_success do |p|
# puts "requesting computation of '#{dialog.first}'"
# p.puts dialog.shift
# end
#
# process.on_failure do |p, status|
# puts "process failed to start (#{status})"
# end
#
# process.on_stdout do |p, data|
# puts "--> #{data}"
# if dialog.empty?
# p.close_input
# else
# puts "requesting computation of '#{dialog.first}'"
# p.puts dialog.shift
# end
# end
#
# process.on_stderr do |p, data|
# puts "[stderr]--> #{data}"
# end
#
# process.on_exit do |p, status|
# puts "process finished with exit status: #{status}"
# end
#
# session.loop
# end
#
# Naturally, not all of the callbacks used above are required. If you
# omit any of them, they will simply not be called. However, you
# *should* do something when the process is successfully started
# (+on_success+), and you *should* do something when data is recieved
# over stdout (+on_stdout+). Lastly, you *must* execute
# <tt>session.loop</tt> in order to process the connection.
#
# The simpler way to use this service is only available when you
# are not handling multiple parallel processes--you can only use it
# when the process you are executing is the only task you are using the
# SSH connection for. It is reminiscent of the popen interface: you
# invoke a command and get three pseudo-IO objects back--one for the
# command's "stdin" stream, one for it's "stdout" stream, and one for
# it's "stderr" stream. You may then write to the "stdin" stream, and
# read from the "stdout" and "stderr" streams.
#
# For example:
#
# require 'net/ssh'
#
# Net::SSH.start( 'host', 'user', 'passwd' ) do |session|
# input, output, error = session.process.popen3( "bc" )
# input.puts "5+5"
# puts "5+5=#{output.read}"
# input.puts "7*12"
# puts "7*12=#{output.read}"
# input.puts "1+2*5/(7+3)"
# puts "1+2*5/(7+3)=#{output.read}"
# input.puts "quit"
# end
#
# One caveat with this format: the process cannot be explicitly
# terminated from the client side--the process must terminate on its
# own (for example, by recieving a "quit" command, as used above). If
# the command does not support any means of gracefully aborting it,
# then the only way to kill the command is to terminate the connection.
#
# A slightly cleaner approach uses blocks to denote the lifespan of the
# process. When the block terminates, the process is killed (if it is
# still running):
#
# require 'net/ssh'
#
# Net::SSH.start( 'host', 'user', 'passwd' ) do |session|
# session.process.popen3( "cat" ) do |input, output, error|
# input.puts "hello"
# puts "echo: #{output.read}"
# input.puts "world"
# puts "echo: #{output.read}"
# end
# end
class Driver
# Create a new Driver instance, using the given log and handlers
# hash.
def initialize( connection, log, handlers )
@connection = connection
@log = log
@handlers = handlers
end
def open( command )
@log.debug "opening '#{command}'" if @log.debug?
process = @handlers[ :open ].call( command )
if block_given?
yield process
@connection.loop
return nil
end
process
end
def popen3( command, &block )
@log.debug "popen3 '#{command}'" if @log.debug?
mgr = @handlers[ :popen3 ]
mgr.popen3( command, &block )
end
end
end # module Process
end # module Service
end # module SSH
end # module Net
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