import os
import sys
import signal
import errno

from . import util

__all__ = ['Popen']

#
# Start child process using fork
#

class Popen(object):
method = 'fork'

def __init__(self, process_obj):
sys.stdout.flush()
sys.stderr.flush()
self.returncode = None
self._launch(process_obj)

def duplicate_for_child(self, fd):
return fd

def poll(self, flag=os.WNOHANG):
if self.returncode is None:
while True:
try:
pid, sts = os.waitpid(self.pid, flag)
except OSError as e:
if e.errno == errno.EINTR:
continue
# Child process not yet created. See #1731717
# e.errno == errno.ECHILD == 10
return None
else:
break
if pid == self.pid:
if os.WIFSIGNALED(sts):
self.returncode = -os.WTERMSIG(sts)
else:
assert os.WIFEXITED(sts)
self.returncode = os.WEXITSTATUS(sts)
return self.returncode

def wait(self, timeout=None):
if self.returncode is None:
if timeout is not None:
from multiprocessing.connection import wait
if not wait([self.sentinel], timeout):
return None
# This shouldn't block if wait() returned successfully.
return self.poll(os.WNOHANG if timeout == 0.0 else 0)
return self.returncode

def terminate(self):
if self.returncode is None:
try:
os.kill(self.pid, signal.SIGTERM)
except ProcessLookupError:
pass
except OSError:
if self.wait(timeout=0.1) is None:
raise

def _launch(self, process_obj):
code = 1
parent_r, child_w = os.pipe()
self.pid = os.fork()
if self.pid == 0:
try:
os.close(parent_r)
if 'random' in sys.modules:
import random
random.seed()
code = process_obj._bootstrap()
finally:
os._exit(code)
else:
os.close(child_w)
util.Finalize(self, os.close, (parent_r,))
self.sentinel = parent_r