/usr/lib/python2.7/dist-packages/parallax/task.py is in python-parallax 1.0.3-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# Copyright (c) 2013, Kristoffer Gronlund
from errno import EINTR
from subprocess import Popen, PIPE
import os
import signal
import sys
import time
import traceback
from parallax import askpass_client
BUFFER_SIZE = 1 << 16
try:
bytes
except NameError:
bytes = str
class Task(object):
"""Starts a process and manages its input and output.
Upon completion, the `exitstatus` attribute is set to the exit status
of the process.
"""
def __init__(self,
host,
port,
user,
cmd,
verbose=False,
quiet=False,
stdin=None,
print_out=False,
inline=False,
inline_stdout=False,
default_user=None):
# Backwards compatibility:
if not isinstance(verbose, bool):
opts = verbose
verbose = opts.verbose
quiet = opts.quiet
try:
print_out = bool(opts.print_out)
except AttributeError:
print_out = False
try:
inline = bool(opts.inline)
except AttributeError:
inline = False
try:
inline_stdout = bool(opts.inline_stdout)
except AttributeError:
inline_stdout = False
default_user = opts.user
self.exitstatus = None
self.host = host
self.pretty_host = host
self.port = port
self.cmd = cmd
if user and user != default_user:
self.pretty_host = '@'.join((user, self.pretty_host))
if port:
self.pretty_host = ':'.join((self.pretty_host, port))
self.proc = None
self.writer = None
self.timestamp = None
self.failures = []
self.killed = False
self.inputbuffer = stdin
self.byteswritten = 0
self.outputbuffer = bytes()
self.errorbuffer = bytes()
self.stdin = None
self.stdout = None
self.stderr = None
self.outfile = None
self.errfile = None
# Set options.
self.verbose = verbose
self.quiet = quiet
self.print_out = print_out
self.inline = inline
self.inline_stdout = inline or inline_stdout
def start(self, nodenum, iomap, writer, askpass_socket=None):
"""Starts the process and registers files with the IOMap."""
self.writer = writer
if writer:
self.outfile, self.errfile = writer.open_files(self.pretty_host)
# Set up the environment.
environ = dict(os.environ)
environ['PARALLAX_NODENUM'] = str(nodenum)
environ['PARALLAX_HOST'] = self.host
# Disable the GNOME pop-up password dialog and allow ssh to use
# askpass.py to get a provided password. If the module file is
# askpass.pyc, we replace the extension.
environ['SSH_ASKPASS'] = askpass_client.executable_path()
if askpass_socket:
environ['PARALLAX_ASKPASS_SOCKET'] = askpass_socket
if self.verbose:
environ['PARALLAX_ASKPASS_VERBOSE'] = '1'
# Work around a mis-feature in ssh where it won't call SSH_ASKPASS
# if DISPLAY is unset.
if 'DISPLAY' not in environ:
environ['DISPLAY'] = 'parallax-gibberish'
# Create the subprocess. Since we carefully call set_cloexec() on
# all open files, we specify close_fds=False.
self.proc = Popen(self.cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE,
close_fds=False, preexec_fn=os.setsid, env=environ)
self.timestamp = time.time()
if self.inputbuffer:
self.stdin = self.proc.stdin
iomap.register_write(self.stdin.fileno(), self.handle_stdin)
else:
self.proc.stdin.close()
self.stdout = self.proc.stdout
iomap.register_read(self.stdout.fileno(), self.handle_stdout)
self.stderr = self.proc.stderr
iomap.register_read(self.stderr.fileno(), self.handle_stderr)
def _kill(self):
"""Signals the process to terminate."""
if self.proc:
try:
os.kill(-self.proc.pid, signal.SIGKILL)
except OSError:
# If the kill fails, then just assume the process is dead.
pass
self.killed = True
def timedout(self):
"""Kills the process and registers a timeout error."""
if not self.killed:
self._kill()
self.failures.append('Timed out')
def interrupted(self):
"""Kills the process and registers an keyboard interrupt error."""
if not self.killed:
self._kill()
self.failures.append('Interrupted')
def cancel(self):
"""Stops a task that has not started."""
self.failures.append('Cancelled')
def elapsed(self):
"""Finds the time in seconds since the process was started."""
return time.time() - self.timestamp
def running(self):
"""Finds if the process has terminated and saves the return code."""
if self.stdin or self.stdout or self.stderr:
return True
if self.proc:
self.exitstatus = self.proc.poll()
if self.exitstatus is None:
if self.killed:
# Set the exitstatus to what it would be if we waited.
self.exitstatus = -signal.SIGKILL
return False
return True
else:
if self.exitstatus < 0:
message = 'Killed by signal %s' % (-self.exitstatus)
self.failures.append(message)
elif self.exitstatus > 0:
message = 'Exited with error code %s' % self.exitstatus
self.failures.append(message)
self.proc = None
return False
def handle_stdin(self, fd, iomap):
"""Called when the process's standard input is ready for writing."""
try:
start = self.byteswritten
if start < len(self.inputbuffer):
chunk = self.inputbuffer[start:start+BUFFER_SIZE]
self.byteswritten = start + os.write(fd, chunk)
else:
self.close_stdin(iomap)
except (OSError, IOError):
_, e, _ = sys.exc_info()
if e.errno != EINTR:
self.close_stdin(iomap)
self.log_exception(e)
def close_stdin(self, iomap):
if self.stdin:
iomap.unregister(self.stdin.fileno())
self.stdin.close()
self.stdin = None
def handle_stdout(self, fd, iomap):
"""Called when the process's standard output is ready for reading."""
try:
buf = os.read(fd, BUFFER_SIZE)
if buf:
if self.inline_stdout:
if self.quiet:
self.outputbuffer += "%s: %s" % (self.host, buf)
else:
self.outputbuffer += buf
if self.outfile:
self.writer.write(self.outfile, buf)
if self.print_out:
for l in buf.split('\n'):
sys.stdout.write('%s: %s\n' % (self.host, l))
else:
self.close_stdout(iomap)
except (OSError, IOError):
_, e, _ = sys.exc_info()
if e.errno != EINTR:
self.close_stdout(iomap)
self.log_exception(e)
def close_stdout(self, iomap):
if self.stdout:
iomap.unregister(self.stdout.fileno())
self.stdout.close()
self.stdout = None
if self.outfile:
self.writer.close(self.outfile)
self.outfile = None
def handle_stderr(self, fd, iomap):
"""Called when the process's standard error is ready for reading."""
try:
buf = os.read(fd, BUFFER_SIZE)
if buf:
if self.inline:
self.errorbuffer += buf
if self.errfile:
self.writer.write(self.errfile, buf)
else:
self.close_stderr(iomap)
except (OSError, IOError):
_, e, _ = sys.exc_info()
if e.errno != EINTR:
self.close_stderr(iomap)
self.log_exception(e)
def close_stderr(self, iomap):
if self.stderr:
iomap.unregister(self.stderr.fileno())
self.stderr.close()
self.stderr = None
if self.errfile:
self.writer.close(self.errfile)
self.errfile = None
def log_exception(self, e):
"""Saves a record of the most recent exception for error reporting."""
if self.verbose:
exc_type, exc_value, exc_traceback = sys.exc_info()
exc = ("Exception: %s, %s, %s" %
(exc_type, exc_value, traceback.format_tb(exc_traceback)))
else:
exc = str(e)
self.failures.append(exc)
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