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Edit File: popen_spawn.py
"""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()