Skip to content
5 contributors

Users who have contributed to this file

@takluyver @blink1073 @eli-b @marc-maurer @robholt
188 lines (155 sloc) 6.02 KB
"""Provides an interface like pexpect.spawn interface using subprocess.Popen
import os
import threading
import subprocess
import sys
import time
import signal
import shlex
from queue import Queue, Empty # Python 3
except ImportError:
from Queue import Queue, Empty # Python 2
from .spawnbase import SpawnBase, PY3
from .exceptions import EOF
from .utils import string_types
class PopenSpawn(SpawnBase):
def __init__(self, cmd, timeout=30, maxread=2000, searchwindowsize=None,
logfile=None, cwd=None, env=None, encoding=None,
codec_errors='strict', preexec_fn=None):
super(PopenSpawn, self).__init__(timeout=timeout, maxread=maxread,
searchwindowsize=searchwindowsize, logfile=logfile,
encoding=encoding, codec_errors=codec_errors)
# Note that `SpawnBase` initializes `self.crlf` to `\r\n`
# because the default behaviour for a PTY is to convert
# incoming LF to `\r\n` (see the `onlcr` flag and
# Here we set
# it to `os.linesep` because that is what the spawned
# application outputs by default and `popen` doesn't translate
# anything.
if encoding is None:
self.crlf = os.linesep.encode ("ascii")
self.crlf = self.string_type (os.linesep)
kwargs = dict(bufsize=0, stdin=subprocess.PIPE,
stderr=subprocess.STDOUT, stdout=subprocess.PIPE,
cwd=cwd, preexec_fn=preexec_fn, env=env)
if sys.platform == 'win32':
startupinfo = subprocess.STARTUPINFO()
startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
kwargs['startupinfo'] = startupinfo
kwargs['creationflags'] = subprocess.CREATE_NEW_PROCESS_GROUP
if isinstance(cmd, string_types) and sys.platform != 'win32':
cmd = shlex.split(cmd, == 'posix')
self.proc = subprocess.Popen(cmd, **kwargs) =
self.closed = False
self._buf = self.string_type()
self._read_queue = Queue()
self._read_thread = threading.Thread(target=self._read_incoming)
_read_reached_eof = False
def read_nonblocking(self, size, timeout):
buf = self._buf
if self._read_reached_eof:
# We have already finished reading. Use up any buffered data,
# then raise EOF
if buf:
self._buf = buf[size:]
return buf[:size]
self.flag_eof = True
raise EOF('End Of File (EOF).')
if timeout == -1:
timeout = self.timeout
elif timeout is None:
timeout = 1e6
t0 = time.time()
while (time.time() - t0) < timeout and size and len(buf) < size:
incoming = self._read_queue.get_nowait()
except Empty:
if incoming is None:
self._read_reached_eof = True
buf += self._decoder.decode(incoming, final=False)
r, self._buf = buf[:size], buf[size:]
self._log(r, 'read')
return r
def _read_incoming(self):
"""Run in a thread to move output from a pipe to a queue."""
fileno = self.proc.stdout.fileno()
while 1:
buf = b''
buf =, 1024)
except OSError as e:
self._log(e, 'read')
if not buf:
# This indicates we have reached EOF
def write(self, s):
'''This is similar to send() except that there is no return value.
def writelines(self, sequence):
'''This calls write() for each element in the sequence.
The sequence can be any iterable object producing strings, typically a
list of strings. This does not add line separators. There is no return
for s in sequence:
def send(self, s):
'''Send data to the subprocess' stdin.
Returns the number of bytes written.
s = self._coerce_send_string(s)
self._log(s, 'send')
b = self._encoder.encode(s, final=False)
if PY3:
return self.proc.stdin.write(b)
# On Python 2, .write() returns None, so we return the length of
# bytes written ourselves. This assumes they all got written.
return len(b)
def sendline(self, s=''):
'''Wraps send(), sending string ``s`` to child process, with os.linesep
automatically appended. Returns number of bytes written. '''
n = self.send(s)
return n + self.send(self.linesep)
def wait(self):
'''Wait for the subprocess to finish.
Returns the exit code.
status = self.proc.wait()
if status >= 0:
self.exitstatus = status
self.signalstatus = None
self.exitstatus = None
self.signalstatus = -status
self.terminated = True
return status
def kill(self, sig):
'''Sends a Unix signal to the subprocess.
Use constants from the :mod:`signal` module to specify which signal.
if sys.platform == 'win32':
if sig in [signal.SIGINT, signal.CTRL_C_EVENT]:
sig = signal.CTRL_C_EVENT
elif sig in [signal.SIGBREAK, signal.CTRL_BREAK_EVENT]:
sig = signal.CTRL_BREAK_EVENT
sig = signal.SIGTERM
os.kill(, sig)
def sendeof(self):
'''Closes the stdin pipe from the writing end.'''