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"""Provides an interface like pexpect.spawn interface using subprocess.Popen
"""
import os
import threading
import subprocess
import sys
import time
import signal
import shlex
try:
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
# https://stackoverflow.com/a/35887657/5397009). 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")
else:
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=os.name == 'posix')
self.proc = subprocess.Popen(cmd, **kwargs)
self.pid = self.proc.pid
self.closed = False
self._buf = self.string_type()
self._read_queue = Queue()
self._read_thread = threading.Thread(target=self._read_incoming)
self._read_thread.setDaemon(True)
self._read_thread.start()
_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]
else:
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:
try:
incoming = self._read_queue.get_nowait()
except Empty:
break
else:
if incoming is None:
self._read_reached_eof = True
break
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''
try:
buf = os.read(fileno, 1024)
except OSError as e:
self._log(e, 'read')
if not buf:
# This indicates we have reached EOF
self._read_queue.put(None)
return
self._read_queue.put(buf)
def write(self, s):
'''This is similar to send() except that there is no return value.
'''
self.send(s)
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
value.
'''
for s in sequence:
self.send(s)
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)
else:
# On Python 2, .write() returns None, so we return the length of
# bytes written ourselves. This assumes they all got written.
self.proc.stdin.write(b)
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
else:
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
else:
sig = signal.SIGTERM
os.kill(self.proc.pid, sig)
def sendeof(self):
'''Closes the stdin pipe from the writing end.'''
self.proc.stdin.close()