gsh/remote_dispatcher.py

   1 # This program is free software; you can redistribute it and/or modify
   2 # it under the terms of the GNU General Public License as published by
   3 # the Free Software Foundation; either version 2 of the License, or
   4 # (at your option) any later version.
   5 #
   6 # This program is distributed in the hope that it will be useful,
   7 # but WITHOUT ANY WARRANTY; without even the implied warranty of
   8 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9 # GNU Library General Public License for more details.
  10 #
  11 # You should have received a copy of the GNU General Public License
  12 # along with this program; if not, write to the Free Software
  13 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  14 #
  15 # See the COPYING file for license information.
  16 #
  17 # Copyright (c) 2006, 2007, 2008 Guillaume Chazarain <guichaz@gmail.com>
  18
  19 import asyncore
  20 import os
  21 import pty
  22 import signal
  23 import sys
  24 import termios
  25
  26 from gsh.buffered_dispatcher import buffered_dispatcher
  27 from gsh import callbacks
  28 from gsh.console import console_output
  29 from gsh import display_names
  30
  31 # Either the remote shell is expecting a command or one is already running
  32 STATE_NAMES = ['not_started', 'idle', 'running', 'terminated', 'dead']
  33
  34 STATE_NOT_STARTED,         \
  35 STATE_IDLE,                \
  36 STATE_RUNNING,             \
  37 STATE_TERMINATED,          \
  38 STATE_DEAD = range(len(STATE_NAMES))
  39
  40 # Count the total number of remote_dispatcher.handle_read() invocations
  41 nr_handle_read = 0
  42
  43 def main_loop_iteration(timeout=None):
  44     """Return the number of remote_dispatcher.handle_read() calls made by this
  45     iteration"""
  46     prev_nr_read = nr_handle_read
  47     asyncore.loop(count=1, timeout=timeout, use_poll=True)
  48     return nr_handle_read - prev_nr_read
  49
  50 def log(msg):
  51     if options.log_file:
  52         fd = options.log_file.fileno()
  53         while msg:
  54             try:
  55                 written = os.write(fd, msg)
  56             except OSError, e:
  57                 print 'Exception while writing log:', options.log_file.name
  58                 print e
  59                 raise asyncore.ExitNow(1)
  60             msg = msg[written:]
  61
  62 class remote_dispatcher(buffered_dispatcher):
  63     """A remote_dispatcher is a ssh process we communicate with"""
  64
  65     def __init__(self, hostname):
  66         self.pid, fd = pty.fork()
  67         if self.pid == 0:
  68             # Child
  69             self.launch_ssh(hostname)
  70             sys.exit(1)
  71
  72         # Parent
  73         buffered_dispatcher.__init__(self, fd)
  74         self.hostname = hostname
  75         self.debug = options.debug
  76         self.enabled = True # shells can be enabled and disabled
  77         self.state = STATE_NOT_STARTED
  78         self.term_size = (-1, -1)
  79         self.display_name = None
  80         self.change_name(hostname)
  81         self.init_string = self.configure_tty() + self.set_prompt()
  82         self.init_string_sent = False
  83         self.read_in_state_not_started = ''
  84         self.command = options.command
  85         self.last_printed_line = ''
  86
  87     def launch_ssh(self, name):
  88         """Launch the ssh command in the child process"""
  89         evaluated = options.ssh % {'host': name}
  90         if evaluated == options.ssh:
  91             evaluated = '%s %s' % (evaluated, name)
  92         os.execlp('/bin/sh', 'sh', '-c', evaluated)
  93
  94     def set_enabled(self, enabled):
  95         if enabled != self.enabled and options.interactive:
  96             # In non-interactive mode, remote processes leave as soon
  97             # as they are terminated, but we don't want to break the
  98             # indentation if all the remaining processes have short names.
  99             display_names.set_enabled(self.display_name, enabled)
 100         self.enabled = enabled
 101
 102     def change_state(self, state):
 103         """Change the state of the remote process, logging the change"""
 104         if state is not self.state:
 105             if self.debug:
 106                 self.print_debug('state => %s' % (STATE_NAMES[state]))
 107             if self.state is STATE_NOT_STARTED:
 108                 self.read_in_state_not_started = ''
 109             self.state = state
 110
 111     def disconnect(self):
 112         """We are no more interested in this remote process"""
 113         try:
 114             os.kill(-self.pid, signal.SIGKILL)
 115         except OSError:
 116             # The process was already dead, no problem
 117             pass
 118         self.read_buffer = ''
 119         self.write_buffer = ''
 120         self.set_enabled(False)
 121         if self.read_in_state_not_started:
 122             self.print_lines(self.read_in_state_not_started)
 123             self.read_in_state_not_started = ''
 124         if options.abort_error and self.state is STATE_NOT_STARTED:
 125             raise asyncore.ExitNow(1)
 126         self.change_state(STATE_DEAD)
 127
 128     def reconnect(self):
 129         """Relaunch and reconnect to this same remote process"""
 130         self.disconnect()
 131         self.close()
 132         remote_dispatcher(self.hostname)
 133
 134     def configure_tty(self):
 135         """We don't want \n to be replaced with \r\n, and we disable the echo"""
 136         attr = termios.tcgetattr(self.fd)
 137         attr[1] &= ~termios.ONLCR # oflag
 138         attr[3] &= ~termios.ECHO # lflag
 139         termios.tcsetattr(self.fd, termios.TCSANOW, attr)
 140         # unsetopt zle prevents Zsh from resetting the tty
 141         return 'unsetopt zle 2> /dev/null;stty -echo -onlcr;'
 142
 143     def seen_prompt_cb(self, unused):
 144         if options.interactive:
 145             self.change_state(STATE_IDLE)
 146         elif self.command:
 147             p1, p2 = callbacks.add('real prompt ends', lambda d: None, True)
 148             self.dispatch_command('PS1="%s""%s\n"\n' % (p1, p2))
 149             self.dispatch_command(self.command + '\n')
 150             self.dispatch_command('exit 2>/dev/null\n')
 151             self.command = None
 152
 153     def set_prompt(self):
 154         """The prompt is important because we detect the readyness of a process
 155         by waiting for its prompt."""
 156         # No right prompt
 157         command_line = 'RPS1=;RPROMPT=;'
 158         command_line += 'PROMPT_COMMAND=;'
 159         command_line += 'TERM=ansi;'
 160         command_line += 'unset HISTFILE;'
 161         prompt1, prompt2 = callbacks.add('prompt', self.seen_prompt_cb, True)
 162         command_line += 'PS1="%s""%s\n"\n' % (prompt1, prompt2)
 163         return command_line
 164
 165     def readable(self):
 166         """We are always interested in reading from active remote processes if
 167         the buffer is OK"""
 168         return self.state != STATE_DEAD and buffered_dispatcher.readable(self)
 169
 170     def handle_expt(self):
 171         if options.interactive:
 172             console_output('Error talking to %s\n' % self.display_name)
 173         else:
 174             pid, status = os.waitpid(self.pid, 0)
 175             exit_code = os.WEXITSTATUS(status)
 176             options.exit_code = max(options.exit_code, exit_code)
 177         self.disconnect()
 178
 179     def print_lines(self, lines):
 180         from gsh.display_names import max_display_name_length
 181         lines = lines.strip('\n')
 182         while True:
 183             no_empty_lines = lines.replace('\n\n', '\n')
 184             if len(no_empty_lines) == len(lines):
 185                 break
 186             lines = no_empty_lines
 187         if not lines:
 188             return
 189         indent = max_display_name_length - len(self.display_name)
 190         prefix = self.display_name + indent * ' ' + ' : '
 191         console_output(prefix + lines.replace('\n', '\n' + prefix) + '\n')
 192         self.last_printed_line = lines[lines.rfind('\n') + 1:]
 193
 194     def handle_read_fast_case(self, data):
 195         """If we are in a fast case we'll avoid the long processing of each
 196         line"""
 197         if self.state is not STATE_RUNNING or callbacks.any_in(data):
 198             # Slow case :-(
 199             return False
 200
 201         last_nl = data.rfind('\n')
 202         if last_nl == -1:
 203             # No '\n' in data => slow case
 204             return False
 205         self.read_buffer = data[last_nl + 1:]
 206         self.print_lines(data[:last_nl])
 207         return True
 208
 209     def handle_read(self):
 210         """We got some output from a remote shell, this is one of the state
 211         machine"""
 212         if self.state == STATE_DEAD:
 213             return
 214         global nr_handle_read
 215         nr_handle_read += 1
 216         new_data = buffered_dispatcher.handle_read(self)
 217         if self.debug:
 218             self.print_debug('==> ' + new_data)
 219         if self.handle_read_fast_case(self.read_buffer):
 220             return
 221         lf_pos = new_data.find('\n')
 222         if lf_pos >= 0:
 223             # Optimization: we knew there were no '\n' in the previous read
 224             # buffer, so we searched only in the new_data and we offset the
 225             # found index by the length of the previous buffer
 226             lf_pos += len(self.read_buffer) - len(new_data)
 227         while lf_pos >= 0:
 228             # For each line in the buffer
 229             line = self.read_buffer[:lf_pos + 1]
 230             if callbacks.process(line):
 231                 pass
 232             elif self.state in (STATE_IDLE, STATE_RUNNING):
 233                 self.print_lines(line)
 234             elif self.state is STATE_NOT_STARTED:
 235                 self.read_in_state_not_started += line
 236                 if 'The authenticity of host' in line:
 237                     msg = line.strip('\n') + ' Closing connection.'
 238                     self.disconnect()
 239                 elif 'REMOTE HOST IDENTIFICATION HAS CHANGED' in line:
 240                     msg = 'Remote host identification has changed.'
 241                 else:
 242                     msg = None
 243
 244                 if msg:
 245                     self.print_lines(msg + ' Consider manually connecting or ' +
 246                                      'using ssh-keyscan.')
 247
 248             # Go to the next line in the buffer
 249             self.read_buffer = self.read_buffer[lf_pos + 1:]
 250             if self.handle_read_fast_case(self.read_buffer):
 251                 return
 252             lf_pos = self.read_buffer.find('\n')
 253         if self.state is STATE_NOT_STARTED and not self.init_string_sent:
 254             self.dispatch_write(self.init_string)
 255             self.init_string_sent = True
 256
 257     def print_unfinished_line(self):
 258         """The unfinished line stayed long enough in the buffer to be printed"""
 259         if self.state is STATE_RUNNING:
 260             if not callbacks.process(self.read_buffer):
 261                 self.print_lines(self.read_buffer)
 262             self.read_buffer = ''
 263
 264     def writable(self):
 265         """Do we want to write something?"""
 266         return self.state != STATE_DEAD and buffered_dispatcher.writable(self)
 267
 268     def handle_write(self):
 269         """Let's write as much as we can"""
 270         num_sent = self.send(self.write_buffer)
 271         if self.debug:
 272             self.print_debug('<== ' + self.write_buffer[:num_sent])
 273         self.write_buffer = self.write_buffer[num_sent:]
 274
 275     def print_debug(self, msg):
 276         """Log some debugging information to the console"""
 277         state = STATE_NAMES[self.state]
 278         msg = msg.encode('string_escape')
 279         console_output('[dbg] %s[%s]: %s\n' % (self.display_name, state, msg))
 280
 281     def get_info(self):
 282         """Return a list with all information available about this process"""
 283         return [self.display_name, self.enabled and 'enabled' or 'disabled',
 284                 STATE_NAMES[self.state] + ':', self.last_printed_line.strip()]
 285
 286     def dispatch_write(self, buf):
 287         """There is new stuff to write when possible"""
 288         if self.state != STATE_DEAD and self.enabled:
 289             buffered_dispatcher.dispatch_write(self, buf)
 290             return True
 291
 292     def dispatch_command(self, command):
 293         if self.dispatch_write(command):
 294             self.change_state(STATE_RUNNING)
 295
 296     def change_name(self, name):
 297         """Change the name of the shell, possibly updating the maximum name
 298         length"""
 299         if not name:
 300             name = self.hostname
 301         self.display_name = display_names.change(self.display_name, name)
 302
 303     def rename(self, string):
 304         """Send to the remote shell, its new name to be shell expanded"""
 305         if string:
 306             rename1, rename2 = callbacks.add('rename', self.change_name, False)
 307             self.dispatch_command('/bin/echo "%s""%s"%s\n' %
 308                                                      (rename1, rename2, string))
 309         else:
 310             self.change_name(self.hostname)
 311
 312     def close(self):
 313         display_names.change(self.display_name, None)
 314         buffered_dispatcher.close(self)