/usr/lib/python2.7/dist-packages/sagenb/interfaces/expect.py is in python-sagenb 0.13+ds1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import os, StringIO, sys, traceback, tempfile, random, shutil
from status import OutputStatus
from sagenb.misc.format import format_for_pexpect
from worksheet_process import WorksheetProcess
from sagenb.misc.misc import (walltime,
set_restrictive_permissions, set_permissive_permissions)
import pexpect
###################################################################
# Expect-based implementation
###################################################################
class WorksheetProcess_ExpectImplementation(WorksheetProcess):
"""
A controlled Python process that executes code using expect.
INPUT:
- ``process_limits`` -- None or a ProcessLimits objects as defined by
the ``sagenb.interfaces.ProcessLimits`` object.
"""
def __init__(self,
process_limits = None,
timeout = 0.05,
python = 'python'):
"""
Initialize this worksheet process.
"""
self._output_status = OutputStatus('', [], True)
self._expect = None
self._is_started = False
self._is_computing = False
self._timeout = timeout
self._prompt = "__SAGE__"
self._filename = ''
self._all_tempdirs = []
self._process_limits = process_limits
self._max_walltime = None
self._start_walltime = None
self._data_dir = None
self._python = python
if process_limits:
u = ''
if process_limits.max_vmem is not None:
u += ' -v %s'%(int(process_limits.max_vmem)*1000)
if process_limits.max_cputime is not None:
u += ' -t %s'%(int(process_limits.max_cputime))
if process_limits.max_processes is not None:
u += ' -u %s'%(int(process_limits.max_processes))
# prepend ulimit options
if u == '':
self._ulimit = u
else:
self._ulimit = 'ulimit %s'%u
else:
self._ulimit = ''
if process_limits and process_limits.max_walltime:
self._max_walltime = process_limits.max_walltime
def command(self):
return self._python
# TODO: The following simply doesn't work -- this is not a valid way to run
# ulimited. Also we should check if ulimit is available before even
# doing this.
return '&&'.join([x for x in [self._ulimit, self._python] if x])
def __del__(self):
try: self._cleanup_tempfiles()
except: pass
try: self._cleanup_data_dir()
except: pass
def _cleanup_data_dir(self):
if self._data_dir is not None:
set_restrictive_permissions(self._data_dir)
def _cleanup_tempfiles(self):
for X in self._all_tempdirs:
try: shutil.rmtree(X, ignore_errors=True)
except: pass
def __repr__(self):
"""
Return string representation of this worksheet process.
"""
return "Pexpect implementation of worksheet process"
###########################################################
# Control the state of the subprocess
###########################################################
def interrupt(self):
"""
Send an interrupt signal to the currently running computation
in the controlled process. This may or may not succeed. Call
``self.is_computing()`` to find out if it did.
"""
if self._expect is None: return
try:
self._expect.sendline(chr(3))
except: pass
def quit(self):
"""
Quit this worksheet process.
"""
if self._expect is None: return
try:
self._expect.sendline(chr(3)) # send ctrl-c
self._expect.sendline('quit_sage()')
except:
pass
try:
os.killpg(self._expect.pid, 9)
os.kill(self._expect.pid, 9)
except OSError:
pass
self._expect = None
self._is_started = False
self._is_computing = False
self._start_walltime = None
self._cleanup_tempfiles()
self._cleanup_data_dir()
def start(self):
"""
Start this worksheet process running.
"""
#print "Starting worksheet with command: '%s'"%self.command()
self._expect = pexpect.spawn(self.command())
self._is_started = True
self._is_computing = False
self._number = 0
self._read()
self._start_walltime = walltime()
def update(self):
"""
This should be called periodically by the server processes.
It does things like checking for timeouts, etc.
"""
self._check_for_walltimeout()
def _check_for_walltimeout(self):
"""
Check if the walltimeout has been reached, and if so, kill
this worksheet process.
"""
if (self._is_started and \
self._max_walltime and self._start_walltime and \
walltime() - self._start_walltime > self._max_walltime):
self.quit()
###########################################################
# Query the state of the subprocess
###########################################################
def is_computing(self):
"""
Return True if a computation is currently running in this worksheet subprocess.
OUTPUT:
- ``bool``
"""
return self._is_computing
def is_started(self):
"""
Return true if this worksheet subprocess has already been started.
OUTPUT:
- ``bool``
"""
return self._is_started
###########################################################
# Sending a string to be executed in the subprocess
###########################################################
def get_tmpdir(self):
"""
Return two strings (local, remote), where local is the name
of a pre-created temporary directory, and remote is the name
of the same directory but on the machine on which the actual
worksheet process is running.
OUTPUT:
- local directory
- remote directory
"""
# In this implementation the remote process is just running
# as the same user on the local machine.
s = tempfile.mkdtemp()
return (s, s)
def execute(self, string, data=None):
"""
Start executing the given string in this subprocess.
INPUT:
- ``string`` -- a string containing code to be executed.
- ``data`` -- a string or None; if given, must specify an
absolute path on the server host filesystem. This may
be ignored by some worksheet process implementations.
"""
if self._expect is None:
self.start()
if self._expect is None:
raise RuntimeError, "unable to start subprocess using command '%s'"%self.command()
self._number += 1
local, remote = self.get_tmpdir()
if data is not None:
# make a symbolic link from the data directory into local tmp directory
self._data = os.path.split(data)[1]
self._data_dir = data
set_permissive_permissions(data)
os.symlink(data, os.path.join(local, self._data))
else:
self._data = ''
self._tempdir = local
sage_input = '_sage_input_%s.py'%self._number
self._filename = os.path.join(self._tempdir, sage_input)
self._so_far = ''
self._is_computing = True
self._all_tempdirs.append(self._tempdir)
open(self._filename,'w').write(format_for_pexpect(string, self._prompt,
self._number))
try:
self._expect.sendline('\nimport os;os.chdir("%s");\nexecfile("%s")'%(
remote, sage_input))
except OSError as msg:
self._is_computing = False
self._so_far = str(msg)
def _read(self):
try:
self._expect.expect(pexpect.EOF, self._timeout)
# got EOF subprocess must have crashed; cleanup
print "got EOF subprocess must have crashed..."
print self._expect.before
self.quit()
except:
pass
###########################################################
# Getting the output so far from a subprocess
###########################################################
def output_status(self):
"""
Return OutputStatus object, which includes output from the
subprocess from the last executed command up until now,
information about files that were created, and whether
computing is now done.
OUTPUT:
- ``OutputStatus`` object.
"""
self._read()
if self._expect is None:
self._is_computing = False
else:
self._so_far = self._expect.before
import re
v = re.findall('START%s.*%s'%(self._number,self._prompt), self._so_far, re.DOTALL)
if len(v) > 0:
self._is_computing = False
s = v[0][len('START%s'%self._number):-len(self._prompt)]
else:
v = re.findall('START%s.*'%self._number, self._so_far, re.DOTALL)
if len(v) > 0:
s = v[0][len('START%s'%self._number):]
else:
s = ''
if s.endswith(self._prompt):
s = s[:-len(self._prompt)]
files = []
if os.path.exists(self._tempdir):
files = [os.path.join(self._tempdir, x) for x in os.listdir(self._tempdir) if x != self._data]
files = [x for x in files if x != self._filename]
return OutputStatus(s, files, not self._is_computing)
class WorksheetProcess_RemoteExpectImplementation(WorksheetProcess_ExpectImplementation):
"""
This worksheet process class implements computation of worksheet
code as another user possibly on another machine, with the
following requirements:
1. ssh keys are setup for passwordless login from the server to the
remote user account, and
2. there is a shared filesystem that both users can write to,
which need not be mounted in the same location.
VULNERABILITIES: It is possible for a malicious user to see code
input by other notebook users whose processes are currently
running. However, the moment any calculation finishes, the file
results are moved back to the the notebook server in a protected
placed, and everything but the input file is deleted, so the
damage that can be done is limited. In particular, users can't
simply browse much from other users.
INPUT:
- ``user_at_host`` -- a string of the form 'username@host'
such that 'ssh user@host' does not require a password, e.g.,
setup by typing ``ssh-keygen`` as the notebook server and
worksheet users, then putting ~/.ssh/id_rsa.pub as the file
.ssh/authorized_keys. You must make the permissions of
files and directories right.
- ``local_directory`` -- (default: None) name of a directory on
the local computer that the notebook server can write to,
which the remote computer also has read/write access to. If
set to ``None``, then first try the environment variable
:envvar:`SAGENB_TMPDIR` if it exists, then :envvar:`TMPDIR`.
Otherwise, fall back to ``/tmp``.
- ``remote_directory`` -- (default: None) if the local_directory is
mounted on the remote machine as a different directory name,
this string is that directory name.
- ``process_limits`` -- None or a ProcessLimits objects as defined by
the ``sagenb.interfaces.ProcessLimits`` object.
"""
def __init__(self,
user_at_host,
remote_python,
local_directory = None,
remote_directory = None,
process_limits = None,
timeout = 0.05):
WorksheetProcess_ExpectImplementation.__init__(self, process_limits, timeout=timeout)
self._user_at_host = user_at_host
if local_directory is None:
local_directory = os.environ.get("SAGENB_TMPDIR")
if local_directory is None:
local_directory = os.environ.get("TMPDIR")
if local_directory is None:
local_directory = "/tmp"
self._local_directory = local_directory
if remote_directory is None:
remote_directory = local_directory
self._remote_directory = remote_directory
self._remote_python = remote_python
def command(self):
if self._ulimit == '':
c = self._remote_python
else:
c = '&&'.join([x for x in [self._ulimit, self._remote_python] if x])
return 'sage-native-execute ssh -t %s "%s"'%(self._user_at_host, c)
def get_tmpdir(self):
"""
Return two strings (local, remote), where local is the name
of a pre-created temporary directory, and remote is the name
of the same directory but on the machine on which the actual
worksheet process is running.
"""
# In this implementation the remote process is just running
# as the same user on the local machine.
local = tempfile.mkdtemp(dir=self._local_directory)
remote = os.path.join(self._remote_directory, local[len(self._local_directory):].lstrip(os.path.sep))
# Make it so local is world read/writable -- so that the remote worksheet
# process can write to it.
set_permissive_permissions(local)
return (local, remote)
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