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 file_transfer
  30
  31 # Either the remote shell is expecting a command or one is already running
  32 STATE_NAMES = ['not_started', 'idle', 'running', 'terminated']
  33
  34 STATE_NOT_STARTED,         \
  35 STATE_IDLE,                \
  36 STATE_RUNNING,             \
  37 STATE_TERMINATED = range(len(STATE_NAMES))
  38
  39 # Count the total number of remote_dispatcher.handle_read() invocations
  40 nr_handle_read = 0
  41
  42 def main_loop_iteration(timeout=None):
  43     """Return the number of remote_dispatcher.handle_read() calls made by this
  44     iteration"""
  45     prev_nr_read = nr_handle_read
  46     asyncore.loop(count=1, timeout=timeout, use_poll=True)
  47     return nr_handle_read - prev_nr_read
  48
  49 def log(msg):
  50     if options.log_file:
  51         options.log_file.write(msg)
  52
  53 class remote_dispatcher(buffered_dispatcher):
  54     """A remote_dispatcher is a ssh process we communicate with"""
  55
  56     def __init__(self, hostname):
  57         self.pid, fd = pty.fork()
  58         if self.pid == 0:
  59             # Child
  60             self.launch_ssh(hostname)
  61             sys.exit(1)
  62
  63         # Parent
  64         buffered_dispatcher.__init__(self, fd)
  65         self.hostname = hostname
  66         self.debug = options.debug
  67         self.active = True # deactived shells are dead forever
  68         self.enabled = True # shells can be enabled and disabled
  69         self.state = STATE_NOT_STARTED
  70         self.term_size = (-1, -1)
  71         self.display_name = ''
  72         self.change_name(hostname)
  73         self.init_string = self.configure_tty() + self.set_prompt()
  74         self.init_string_sent = False
  75         self.read_in_state_not_started = ''
  76         self.command = options.command
  77
  78     def launch_ssh(self, name):
  79         """Launch the ssh command in the child process"""
  80         evaluated = options.ssh % {'host': name}
  81         if evaluated == options.ssh:
  82             evaluated = '%s %s' % (evaluated, name)
  83         os.execlp('/bin/sh', 'sh', '-c', evaluated)
  84
  85     def set_enabled(self, enabled):
  86         from gsh.dispatchers import update_max_display_name_length
  87         self.enabled = enabled
  88         if options.interactive:
  89             # In non-interactive mode, remote processes leave as soon
  90             # as they are terminated, but we don't want to break the
  91             # indentation if all the remaining processes have short names.
  92             l = len(self.display_name)
  93             if not enabled:
  94                 l = -l
  95             update_max_display_name_length(l)
  96
  97     def change_state(self, state):
  98         """Change the state of the remote process, logging the change"""
  99         if state is not self.state:
 100             if self.debug:
 101                 self.print_debug('state => %s' % (STATE_NAMES[state]))
 102             if self.state == STATE_NOT_STARTED:
 103                 self.read_in_state_not_started = ''
 104             self.state = state
 105
 106     def disconnect(self):
 107         """We are no more interested in this remote process"""
 108         try:
 109             os.kill(self.pid, signal.SIGKILL)
 110         except OSError:
 111             # The process was already dead, no problem
 112             pass
 113         self.read_buffer = ''
 114         self.write_buffer = ''
 115         self.active = False
 116         self.set_enabled(False)
 117         if self.read_in_state_not_started:
 118             self.print_lines(self.read_in_state_not_started)
 119             self.read_in_state_not_started = ''
 120         if options.abort_error and self.state is STATE_NOT_STARTED:
 121             raise asyncore.ExitNow(1)
 122
 123     def reconnect(self):
 124         """Relaunch and reconnect to this same remote process"""
 125         self.disconnect()
 126         self.close()
 127         remote_dispatcher(self.hostname)
 128
 129     def configure_tty(self):
 130         """We don't want \n to be replaced with \r\n, and we disable the echo"""
 131         attr = termios.tcgetattr(self.fd)
 132         attr[1] &= ~termios.ONLCR # oflag
 133         attr[3] &= ~termios.ECHO # lflag
 134         termios.tcsetattr(self.fd, termios.TCSANOW, attr)
 135         # unsetopt zle prevents Zsh from resetting the tty
 136         return 'unsetopt zle 2> /dev/null;stty -echo -onlcr;'
 137
 138     def seen_prompt_cb(self, unused):
 139         if options.interactive:
 140             self.change_state(STATE_IDLE)
 141         elif self.command:
 142             self.dispatch_command(self.command + '\n')
 143             self.command = None
 144         else:
 145             self.change_state(STATE_TERMINATED)
 146             self.disconnect()
 147
 148     def set_prompt(self):
 149         """The prompt is important because we detect the readyness of a process
 150         by waiting for its prompt."""
 151         # No right prompt
 152         command_line = 'RPS1=;RPROMPT=;'
 153         command_line += 'TERM=ansi;'
 154         command_line += 'unset HISTFILE;'
 155         prompt1, prompt2 = callbacks.add('prompt', self.seen_prompt_cb, True)
 156         command_line += 'PS1="%s""%s\n"\n' % (prompt1, prompt2)
 157         return command_line
 158
 159     def readable(self):
 160         """We are always interested in reading from active remote processes if
 161         the buffer is OK"""
 162         return self.active and buffered_dispatcher.readable(self)
 163
 164     def handle_error(self):
 165         """An exception may or may not lead to a disconnection"""
 166         if buffered_dispatcher.handle_error(self):
 167             console_output('Error talking to %s\n' % self.display_name)
 168             self.disconnect()
 169
 170     def print_lines(self, lines):
 171         from gsh.dispatchers import max_display_name_length
 172         lines = lines.strip('\n')
 173         while True:
 174             no_empty_lines = lines.replace('\n\n', '\n')
 175             if len(no_empty_lines) == len(lines):
 176                 break
 177             lines = no_empty_lines
 178         if not lines:
 179             return
 180         indent = max_display_name_length - len(self.display_name)
 181         prefix = self.display_name + indent * ' ' + ': '
 182         console_output(prefix + lines.replace('\n', '\n' + prefix) + '\n')
 183
 184     def handle_read_fast_case(self, data):
 185         """If we are in a fast case we'll avoid the long processing of each
 186         line"""
 187         if self.state is not STATE_RUNNING or callbacks.any_in(data):
 188             # Slow case :-(
 189             return False
 190
 191         last_nl = data.rfind('\n')
 192         if last_nl == -1:
 193             # No '\n' in data => slow case
 194             return False
 195         self.read_buffer = data[last_nl + 1:]
 196         self.print_lines(data[:last_nl])
 197         return True
 198
 199     def handle_read(self):
 200         """We got some output from a remote shell, this is one of the state
 201         machine"""
 202         if not self.active:
 203             return
 204         global nr_handle_read
 205         nr_handle_read += 1
 206         new_data = buffered_dispatcher.handle_read(self)
 207         if self.debug:
 208             self.print_debug('==> ' + new_data)
 209         if self.handle_read_fast_case(self.read_buffer):
 210             return
 211         lf_pos = new_data.find('\n')
 212         if lf_pos >= 0:
 213             # Optimization: we knew there were no '\n' in the previous read
 214             # buffer, so we searched only in the new_data and we offset the
 215             # found index by the length of the previous buffer
 216             lf_pos += len(self.read_buffer) - len(new_data)
 217         while lf_pos >= 0:
 218             # For each line in the buffer
 219             line = self.read_buffer[:lf_pos + 1]
 220             if callbacks.process(line):
 221                 pass
 222             elif self.state in (STATE_IDLE, STATE_RUNNING):
 223                 self.print_lines(line)
 224             elif self.state is STATE_NOT_STARTED:
 225                 self.read_in_state_not_started += line
 226                 if 'The authenticity of host' in line:
 227                     msg = line.strip('\n') + ' Closing connection.'
 228                     self.disconnect()
 229                 elif 'REMOTE HOST IDENTIFICATION HAS CHANGED' in line:
 230                     msg = 'Remote host identification has changed.'
 231                 else:
 232                     msg = None
 233
 234                 if msg:
 235                     self.print_lines(msg + ' Consider manually connecting or ' +
 236                                      'using ssh-keyscan.')
 237
 238             # Go to the next line in the buffer
 239             self.read_buffer = self.read_buffer[lf_pos + 1:]
 240             if self.handle_read_fast_case(self.read_buffer):
 241                 return
 242             lf_pos = self.read_buffer.find('\n')
 243         if self.state is STATE_NOT_STARTED and not self.init_string_sent:
 244             self.dispatch_write(self.init_string)
 245             self.init_string_sent = True
 246
 247     def print_unfinished_line(self):
 248         """The unfinished line stayed long enough in the buffer to be printed"""
 249         if self.state is STATE_RUNNING:
 250             self.print_lines(self.read_buffer)
 251             self.read_buffer = ''
 252
 253     def writable(self):
 254         """Do we want to write something?"""
 255         return self.active and buffered_dispatcher.writable(self)
 256
 257     def handle_write(self):
 258         """Let's write as much as we can"""
 259         num_sent = self.send(self.write_buffer)
 260         if self.debug:
 261             self.print_debug('<== ' + self.write_buffer[:num_sent])
 262         self.write_buffer = self.write_buffer[num_sent:]
 263
 264     def print_debug(self, msg):
 265         """Log some debugging information to the console"""
 266         state = STATE_NAMES[self.state]
 267         msg = msg.encode('string_escape')
 268         console_output('[dbg] %s[%s]: %s\n' % (self.display_name, state, msg))
 269
 270     def get_info(self):
 271         """Return a list with all information available about this process"""
 272         if self.active:
 273             state = STATE_NAMES[self.state]
 274         else:
 275             state = ''
 276
 277         if self.debug:
 278             debug = 'debug'
 279         else:
 280             debug = ''
 281
 282         return [self.display_name, 'fd:%d' % (self.fd),
 283                 'r:%d' % (len(self.read_buffer)),
 284                 'w:%d' % (len(self.write_buffer)),
 285                 self.active and 'active' or 'dead',
 286                 self.enabled and 'enabled' or 'disabled',
 287                 state,
 288                 debug]
 289
 290     def dispatch_write(self, buf):
 291         """There is new stuff to write when possible"""
 292         if self.active and self.enabled:
 293             buffered_dispatcher.dispatch_write(self, buf)
 294             return True
 295
 296     def dispatch_command(self, command):
 297         if self.dispatch_write(command):
 298             self.change_state(STATE_RUNNING)
 299
 300     def change_name(self, name):
 301         """Change the name of the shell, possibly updating the maximum name
 302         length"""
 303         from gsh import dispatchers
 304         if not name:
 305             name = self.hostname
 306         previous_name_len = len(self.display_name)
 307         self.display_name = None
 308         self.display_name = dispatchers.make_unique_name(name)
 309         dispatchers.update_max_display_name_length(len(self.display_name))
 310         dispatchers.update_max_display_name_length(-previous_name_len)
 311
 312     def rename(self, string):
 313         """Send to the remote shell, its new name to be shell expanded"""
 314         if string:
 315             rename1, rename2 = callbacks.add('rename', self.change_name, False)
 316             self.dispatch_command('/bin/echo "%s""%s"%s\n' %
 317                                                      (rename1, rename2, string))
 318         else:
 319             self.change_name(self.hostname)
 320
 321     def __str__(self):
 322         return self.display_name