1import io
2import os
3
4from .context import reduction, set_spawning_popen
5if not reduction.HAVE_SEND_HANDLE:
6    raise ImportError('No support for sending fds between processes')
7from . import forkserver
8from . import popen_fork
9from . import spawn
10from . import util
11
12
13__all__ = ['Popen']
14
15#
16# Wrapper for an fd used while launching a process
17#
18
19class _DupFd(object):
20    def __init__(self, ind):
21        self.ind = ind
22    def detach(self):
23        return forkserver.get_inherited_fds()[self.ind]
24
25#
26# Start child process using a server process
27#
28
29class Popen(popen_fork.Popen):
30    method = 'forkserver'
31    DupFd = _DupFd
32
33    def __init__(self, process_obj):
34        self._fds = []
35        super().__init__(process_obj)
36
37    def duplicate_for_child(self, fd):
38        self._fds.append(fd)
39        return len(self._fds) - 1
40
41    def _launch(self, process_obj):
42        prep_data = spawn.get_preparation_data(process_obj._name)
43        buf = io.BytesIO()
44        set_spawning_popen(self)
45        try:
46            reduction.dump(prep_data, buf)
47            reduction.dump(process_obj, buf)
48        finally:
49            set_spawning_popen(None)
50
51        self.sentinel, w = forkserver.connect_to_new_process(self._fds)
52        util.Finalize(self, os.close, (self.sentinel,))
53        with open(w, 'wb', closefd=True) as f:
54            f.write(buf.getbuffer())
55        self.pid = forkserver.read_unsigned(self.sentinel)
56
57    def poll(self, flag=os.WNOHANG):
58        if self.returncode is None:
59            from multiprocessing.connection import wait
60            timeout = 0 if flag == os.WNOHANG else None
61            if not wait([self.sentinel], timeout):
62                return None
63            try:
64                self.returncode = forkserver.read_unsigned(self.sentinel)
65            except (OSError, EOFError):
66                # The process ended abnormally perhaps because of a signal
67                self.returncode = 255
68        return self.returncode
69