251 lines
8.2 KiB
Python
251 lines
8.2 KiB
Python
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# Copyright 2019, David Wilson
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# 1. Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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#
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# 3. Neither the name of the copyright holder nor the names of its contributors
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# may be used to endorse or promote products derived from this software without
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# specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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# !mitogen: minify_safe
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import errno
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import logging
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import os
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import random
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import sys
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import threading
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import traceback
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import mitogen.core
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import mitogen.parent
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from mitogen.core import b
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LOG = logging.getLogger(__name__)
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# Python 2.4/2.5 cannot support fork+threads whatsoever, it doesn't even fix up
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# interpreter state. So 2.4/2.5 interpreters start .local() contexts for
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# isolation instead. Since we don't have any crazy memory sharing problems to
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# avoid, there is no virginal fork parent either. The child is started directly
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# from the login/become process. In future this will be default everywhere,
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# fork is brainwrong from the stone age.
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FORK_SUPPORTED = sys.version_info >= (2, 6)
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class Error(mitogen.core.StreamError):
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pass
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def fixup_prngs():
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"""
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Add 256 bits of /dev/urandom to OpenSSL's PRNG in the child, and re-seed
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the random package with the same data.
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"""
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s = os.urandom(256 // 8)
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random.seed(s)
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if 'ssl' in sys.modules:
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sys.modules['ssl'].RAND_add(s, 75.0)
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def reset_logging_framework():
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"""
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After fork, ensure any logging.Handler locks are recreated, as a variety of
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threads in the parent may have been using the logging package at the moment
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of fork.
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It is not possible to solve this problem in general; see :gh:issue:`150`
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for a full discussion.
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"""
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logging._lock = threading.RLock()
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# The root logger does not appear in the loggerDict.
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logging.Logger.manager.loggerDict = {}
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logging.getLogger().handlers = []
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def on_fork():
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"""
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Should be called by any program integrating Mitogen each time the process
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is forked, in the context of the new child.
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"""
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reset_logging_framework() # Must be first!
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fixup_prngs()
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mitogen.core.Latch._on_fork()
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mitogen.core.Side._on_fork()
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mitogen.core.ExternalContext.service_stub_lock = threading.Lock()
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mitogen__service = sys.modules.get('mitogen.service')
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if mitogen__service:
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mitogen__service._pool_lock = threading.Lock()
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def handle_child_crash():
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"""
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Respond to _child_main() crashing by ensuring the relevant exception is
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logged to /dev/tty.
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"""
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tty = open('/dev/tty', 'wb')
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tty.write('\n\nFORKED CHILD PID %d CRASHED\n%s\n\n' % (
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os.getpid(),
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traceback.format_exc(),
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))
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tty.close()
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os._exit(1)
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def _convert_exit_status(status):
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"""
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Convert a :func:`os.waitpid`-style exit status to a :mod:`subprocess` style
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exit status.
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"""
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if os.WIFEXITED(status):
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return os.WEXITSTATUS(status)
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elif os.WIFSIGNALED(status):
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return -os.WTERMSIG(status)
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elif os.WIFSTOPPED(status):
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return -os.WSTOPSIG(status)
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class Process(mitogen.parent.Process):
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def poll(self):
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try:
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pid, status = os.waitpid(self.pid, os.WNOHANG)
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except OSError:
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e = sys.exc_info()[1]
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if e.args[0] == errno.ECHILD:
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LOG.warn('%r: waitpid(%r) produced ECHILD', self, self.pid)
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return
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raise
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if not pid:
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return
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return _convert_exit_status(status)
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class Options(mitogen.parent.Options):
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#: Reference to the importer, if any, recovered from the parent.
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importer = None
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#: User-supplied function for cleaning up child process state.
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on_fork = None
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def __init__(self, old_router, max_message_size, on_fork=None, debug=False,
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profiling=False, unidirectional=False, on_start=None,
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name=None):
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if not FORK_SUPPORTED:
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raise Error(self.python_version_msg)
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# fork method only supports a tiny subset of options.
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super(Options, self).__init__(
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max_message_size=max_message_size, debug=debug,
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profiling=profiling, unidirectional=unidirectional, name=name,
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)
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self.on_fork = on_fork
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self.on_start = on_start
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responder = getattr(old_router, 'responder', None)
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if isinstance(responder, mitogen.parent.ModuleForwarder):
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self.importer = responder.importer
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class Connection(mitogen.parent.Connection):
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options_class = Options
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child_is_immediate_subprocess = True
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python_version_msg = (
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"The mitogen.fork method is not supported on Python versions "
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"prior to 2.6, since those versions made no attempt to repair "
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"critical interpreter state following a fork. Please use the "
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"local() method instead."
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)
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name_prefix = u'fork'
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def start_child(self):
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parentfp, childfp = mitogen.parent.create_socketpair()
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pid = os.fork()
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if pid:
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childfp.close()
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return Process(pid, stdin=parentfp, stdout=parentfp)
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else:
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parentfp.close()
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self._wrap_child_main(childfp)
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def _wrap_child_main(self, childfp):
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try:
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self._child_main(childfp)
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except BaseException:
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handle_child_crash()
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def get_econtext_config(self):
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config = super(Connection, self).get_econtext_config()
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config['core_src_fd'] = None
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config['importer'] = self.options.importer
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config['send_ec2'] = False
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config['setup_package'] = False
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if self.options.on_start:
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config['on_start'] = self.options.on_start
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return config
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def _child_main(self, childfp):
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on_fork()
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if self.options.on_fork:
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self.options.on_fork()
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mitogen.core.set_block(childfp.fileno())
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childfp.send(b('MITO002\n'))
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# Expected by the ExternalContext.main().
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os.dup2(childfp.fileno(), 1)
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os.dup2(childfp.fileno(), 100)
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# Overwritten by ExternalContext.main(); we must replace the
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# parent-inherited descriptors that were closed by Side._on_fork() to
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# avoid ExternalContext.main() accidentally allocating new files over
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# the standard handles.
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os.dup2(childfp.fileno(), 0)
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# Avoid corrupting the stream on fork crash by dupping /dev/null over
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# stderr. Instead, handle_child_crash() uses /dev/tty to log errors.
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devnull = os.open('/dev/null', os.O_WRONLY)
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if devnull != 2:
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os.dup2(devnull, 2)
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os.close(devnull)
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# If we're unlucky, childfp.fileno() may coincidentally be one of our
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# desired FDs. In that case closing it breaks ExternalContext.main().
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if childfp.fileno() not in (0, 1, 100):
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childfp.close()
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mitogen.core.IOLOG.setLevel(logging.INFO)
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try:
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try:
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mitogen.core.ExternalContext(self.get_econtext_config()).main()
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except Exception:
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# TODO: report exception somehow.
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os._exit(72)
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finally:
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# Don't trigger atexit handlers, they were copied from the parent.
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os._exit(0)
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