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673 lines
22 KiB
Python
673 lines
22 KiB
Python
# Copyright 2017, 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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"""
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Helper functions intended to be executed on the target. These are entrypoints
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for file transfer, module execution and sundry bits like changing file modes.
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"""
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from __future__ import absolute_import
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from __future__ import unicode_literals
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import errno
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import functools
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import grp
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import json
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import logging
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import operator
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import os
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import pwd
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import re
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import signal
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import stat
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import subprocess
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import sys
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import tempfile
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import traceback
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import types
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import mitogen.core
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import mitogen.fork
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import mitogen.parent
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import mitogen.service
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# Ansible since PR #41749 inserts "import __main__" into
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# ansible.module_utils.basic. Mitogen's importer will refuse such an import, so
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# we must setup a fake "__main__" before that module is ever imported. The
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# str() is to cast Unicode to bytes on Python 2.6.
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if not sys.modules.get(str('__main__')):
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sys.modules[str('__main__')] = types.ModuleType(str('__main__'))
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import ansible.module_utils.json_utils
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import ansible_mitogen.runner
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LOG = logging.getLogger(__name__)
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MAKE_TEMP_FAILED_MSG = (
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"Unable to find a useable temporary directory. This likely means no\n"
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"system-supplied TMP directory can be written to, or all directories\n"
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"were mounted on 'noexec' filesystems.\n"
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"\n"
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"The following paths were tried:\n"
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" %(namelist)s\n"
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"\n"
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"Please check '-vvv' output for a log of individual path errors."
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)
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#: Initialized to an econtext.parent.Context pointing at a pristine fork of
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#: the target Python interpreter before it executes any code or imports.
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_fork_parent = None
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#: Set by init_child() to a list of candidate $variable-expanded and
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#: tilde-expanded directory paths that may be usable as a temporary directory.
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_candidate_temp_dirs = None
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#: Set by reset_temp_dir() to the single temporary directory that will exist
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#: for the duration of the process.
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temp_dir = None
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def get_small_file(context, path):
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"""
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Basic in-memory caching module fetcher. This generates an one roundtrip for
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every previously unseen file, so it is only a temporary solution.
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:param context:
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Context we should direct FileService requests to. For now (and probably
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forever) this is just the top-level Mitogen connection manager process.
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:param path:
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Path to fetch from FileService, must previously have been registered by
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a privileged context using the `register` command.
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:returns:
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Bytestring file data.
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"""
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pool = mitogen.service.get_or_create_pool(router=context.router)
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service = pool.get_service('mitogen.service.PushFileService')
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return service.get(path)
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def transfer_file(context, in_path, out_path, sync=False, set_owner=False):
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"""
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Streamily download a file from the connection multiplexer process in the
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controller.
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:param mitogen.core.Context context:
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Reference to the context hosting the FileService that will be used to
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fetch the file.
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:param bytes in_path:
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FileService registered name of the input file.
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:param bytes out_path:
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Name of the output path on the local disk.
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:param bool sync:
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If :data:`True`, ensure the file content and metadat are fully on disk
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before renaming the temporary file over the existing file. This should
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ensure in the case of system crash, either the entire old or new file
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are visible post-reboot.
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:param bool set_owner:
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If :data:`True`, look up the metadata username and group on the local
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system and file the file owner using :func:`os.fchmod`.
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"""
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out_path = os.path.abspath(out_path)
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fd, tmp_path = tempfile.mkstemp(suffix='.tmp',
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prefix='.ansible_mitogen_transfer-',
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dir=os.path.dirname(out_path))
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fp = os.fdopen(fd, 'wb', mitogen.core.CHUNK_SIZE)
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LOG.debug('transfer_file(%r) temporary file: %s', out_path, tmp_path)
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try:
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try:
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ok, metadata = mitogen.service.FileService.get(
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context=context,
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path=in_path,
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out_fp=fp,
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)
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if not ok:
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raise IOError('transfer of %r was interrupted.' % (in_path,))
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os.fchmod(fp.fileno(), metadata['mode'])
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if set_owner:
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set_fd_owner(fp.fileno(), metadata['owner'], metadata['group'])
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finally:
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fp.close()
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if sync:
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os.fsync(fp.fileno())
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os.rename(tmp_path, out_path)
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except BaseException:
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os.unlink(tmp_path)
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raise
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os.utime(out_path, (metadata['atime'], metadata['mtime']))
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def prune_tree(path):
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"""
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Like shutil.rmtree(), but log errors rather than discard them, and do not
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waste multiple os.stat() calls discovering whether the object can be
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deleted, just try deleting it instead.
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"""
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try:
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os.unlink(path)
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return
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except OSError as e:
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if not (os.path.isdir(path) and
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e.args[0] in (errno.EPERM, errno.EISDIR)):
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LOG.error('prune_tree(%r): %s', path, e)
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return
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try:
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# Ensure write access for readonly directories. Ignore error in case
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# path is on a weird filesystem (e.g. vfat).
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os.chmod(path, int('0700', 8))
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except OSError as e:
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LOG.warning('prune_tree(%r): %s', path, e)
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try:
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for name in os.listdir(path):
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if name not in ('.', '..'):
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prune_tree(os.path.join(path, name))
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os.rmdir(path)
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except OSError as e:
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LOG.error('prune_tree(%r): %s', path, e)
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def _on_broker_shutdown():
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"""
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Respond to broker shutdown (graceful termination by parent, or loss of
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connection to parent) by deleting our sole temporary directory.
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"""
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prune_tree(temp_dir)
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def find_good_temp_dir():
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"""
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Given a list of candidate temp directories extracted from ``ansible.cfg``
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and stored in _candidate_temp_dirs, combine it with the Python-builtin list
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of candidate directories used by :mod:`tempfile`, then iteratively try each
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in turn until one is found that is both writeable and executable.
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"""
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paths = [os.path.expandvars(os.path.expanduser(p))
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for p in _candidate_temp_dirs]
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paths.extend(tempfile._candidate_tempdir_list())
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for path in paths:
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try:
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tmp = tempfile.NamedTemporaryFile(
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prefix='ansible_mitogen_find_good_temp_dir',
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dir=path,
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)
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except (OSError, IOError) as e:
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LOG.debug('temp dir %r unusable: %s', path, e)
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continue
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try:
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try:
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os.chmod(tmp.name, int('0700', 8))
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except OSError as e:
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LOG.debug('temp dir %r unusable: %s: chmod failed: %s',
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path, e)
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continue
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try:
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# access(.., X_OK) is sufficient to detect noexec.
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if not os.access(tmp.name, os.X_OK):
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raise OSError('filesystem appears to be mounted noexec')
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except OSError as e:
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LOG.debug('temp dir %r unusable: %s: %s', path, e)
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continue
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LOG.debug('Selected temp directory: %r (from %r)', path, paths)
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return path
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finally:
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tmp.close()
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raise IOError(MAKE_TEMP_FAILED_MSG % {
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'paths': '\n '.join(paths),
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})
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@mitogen.core.takes_econtext
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def reset_temp_dir(econtext):
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"""
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Create one temporary directory to be reused by all runner.py invocations
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for the lifetime of the process. The temporary directory is changed for
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each forked job, and emptied as necessary by runner.py::_cleanup_temp()
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after each module invocation.
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The result is that a context need only create and delete one directory
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during startup and shutdown, and no further filesystem writes need occur
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assuming no modules execute that create temporary files.
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"""
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global temp_dir
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# https://github.com/dw/mitogen/issues/239
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basedir = find_good_temp_dir()
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temp_dir = tempfile.mkdtemp(prefix='ansible_mitogen_', dir=basedir)
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# This must be reinstalled in forked children too, since the Broker
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# instance from the parent process does not carry over to the new child.
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mitogen.core.listen(econtext.broker, 'shutdown', _on_broker_shutdown)
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@mitogen.core.takes_econtext
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def init_child(econtext, log_level, candidate_temp_dirs):
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"""
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Called by ContextService immediately after connection; arranges for the
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(presently) spotless Python interpreter to be forked, where the newly
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forked interpreter becomes the parent of any newly forked future
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interpreters.
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This is necessary to prevent modules that are executed in-process from
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polluting the global interpreter state in a way that effects explicitly
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isolated modules.
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:param int log_level:
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Logging package level active in the master.
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:param list[str] candidate_temp_dirs:
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List of $variable-expanded and tilde-expanded directory names to add to
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candidate list of temporary directories.
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:returns:
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Dict like::
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{
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'fork_context': mitogen.core.Context.
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'home_dir': str.
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}
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Where `fork_context` refers to the newly forked 'fork parent' context
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the controller will use to start forked jobs, and `home_dir` is the
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home directory for the active user account.
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"""
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global _candidate_temp_dirs
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_candidate_temp_dirs = candidate_temp_dirs
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global _fork_parent
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mitogen.parent.upgrade_router(econtext)
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_fork_parent = econtext.router.fork()
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reset_temp_dir(econtext)
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# Copying the master's log level causes log messages to be filtered before
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# they reach LogForwarder, thus reducing an influx of tiny messges waking
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# the connection multiplexer process in the master.
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LOG.setLevel(log_level)
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logging.getLogger('ansible_mitogen').setLevel(log_level)
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return {
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'fork_context': _fork_parent,
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'home_dir': mitogen.core.to_text(os.path.expanduser('~')),
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'temp_dir': temp_dir,
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}
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@mitogen.core.takes_econtext
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def create_fork_child(econtext):
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"""
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For helper functions executed in the fork parent context, arrange for
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the context's router to be upgraded as necessary and for a new child to be
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prepared.
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"""
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mitogen.parent.upgrade_router(econtext)
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context = econtext.router.fork()
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context.call(reset_temp_dir)
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LOG.debug('create_fork_child() -> %r', context)
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return context
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def run_module(kwargs):
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"""
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Set up the process environment in preparation for running an Ansible
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module. This monkey-patches the Ansible libraries in various places to
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prevent it from trying to kill the process on completion, and to prevent it
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from reading sys.stdin.
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"""
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runner_name = kwargs.pop('runner_name')
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klass = getattr(ansible_mitogen.runner, runner_name)
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impl = klass(**kwargs)
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return impl.run()
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def _get_async_dir():
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return os.path.expanduser(
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os.environ.get('ANSIBLE_ASYNC_DIR', '~/.ansible_async')
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)
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class AsyncRunner(object):
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def __init__(self, job_id, timeout_secs, econtext, kwargs):
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self.job_id = job_id
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self.timeout_secs = timeout_secs
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self.econtext = econtext
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self.kwargs = kwargs
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self._timed_out = False
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self._init_path()
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def _init_path(self):
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async_dir = _get_async_dir()
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if not os.path.exists(async_dir):
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os.makedirs(async_dir)
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self.path = os.path.join(async_dir, self.job_id)
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def _update(self, dct):
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"""
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Update an async job status file.
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"""
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LOG.info('%r._update(%r, %r)', self, self.job_id, dct)
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dct.setdefault('ansible_job_id', self.job_id)
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dct.setdefault('data', '')
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with open(self.path + '.tmp', 'w') as fp:
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fp.write(json.dumps(dct))
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os.rename(self.path + '.tmp', self.path)
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def _on_sigalrm(self, signum, frame):
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"""
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Respond to SIGALRM (job timeout) by updating the job file and killing
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the process.
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"""
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msg = "Job reached maximum time limit of %d seconds." % (
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self.timeout_secs,
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)
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self._update({
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"failed": 1,
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"finished": 1,
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"msg": msg,
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})
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self._timed_out = True
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self.econtext.broker.shutdown()
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def _install_alarm(self):
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signal.signal(signal.SIGALRM, self._on_sigalrm)
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signal.alarm(self.timeout_secs)
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def _run_module(self):
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kwargs = dict(self.kwargs, **{
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'detach': True,
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'econtext': self.econtext,
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'emulate_tty': False,
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})
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return run_module(kwargs)
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def _parse_result(self, dct):
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filtered, warnings = (
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ansible.module_utils.json_utils.
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_filter_non_json_lines(dct['stdout'])
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)
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result = json.loads(filtered)
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result.setdefault('warnings', []).extend(warnings)
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result['stderr'] = dct['stderr']
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self._update(result)
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def _run(self):
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"""
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1. Immediately updates the status file to mark the job as started.
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2. Installs a timer/signal handler to implement the time limit.
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3. Runs as with run_module(), writing the result to the status file.
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:param dict kwargs:
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Runner keyword arguments.
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:param str job_id:
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String job ID.
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:param int timeout_secs:
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If >0, limit the task's maximum run time.
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"""
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self._update({
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'started': 1,
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'finished': 0,
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'pid': os.getpid()
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})
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if self.timeout_secs > 0:
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self._install_alarm()
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dct = self._run_module()
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if not self._timed_out:
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# After SIGALRM fires, there is a window between broker responding
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# to shutdown() by killing the process, and work continuing on the
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# main thread. If main thread was asleep in at least
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# basic.py/select.select(), an EINTR will be raised. We want to
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# discard that exception.
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try:
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self._parse_result(dct)
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except Exception:
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self._update({
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"failed": 1,
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"msg": traceback.format_exc(),
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"data": dct['stdout'], # temporary notice only
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"stderr": dct['stderr']
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})
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def run(self):
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try:
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try:
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self._run()
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except Exception:
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self._update({
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"failed": 1,
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"msg": traceback.format_exc(),
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})
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finally:
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self.econtext.broker.shutdown()
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@mitogen.core.takes_econtext
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def run_module_async(kwargs, job_id, timeout_secs, econtext):
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"""
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Execute a module with its run status and result written to a file,
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terminating on the process on completion. This function must run in a child
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forked using :func:`create_fork_child`.
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"""
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arunner = AsyncRunner(job_id, timeout_secs, econtext, kwargs)
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arunner.run()
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def get_user_shell():
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"""
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For commands executed directly via an SSH command-line, SSH looks up the
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user's shell via getpwuid() and only defaults to /bin/sh if that field is
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missing or empty.
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"""
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try:
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pw_shell = pwd.getpwuid(os.geteuid()).pw_shell
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except KeyError:
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pw_shell = None
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return pw_shell or '/bin/sh'
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def exec_args(args, in_data='', chdir=None, shell=None, emulate_tty=False):
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"""
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Run a command in a subprocess, emulating the argument handling behaviour of
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SSH.
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:param list[str]:
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Argument vector.
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:param bytes in_data:
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Optional standard input for the command.
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:param bool emulate_tty:
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If :data:`True`, arrange for stdout and stderr to be merged into the
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stdout pipe and for LF to be translated into CRLF, emulating the
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behaviour of a TTY.
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:return:
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(return code, stdout bytes, stderr bytes)
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"""
|
|
LOG.debug('exec_args(%r, ..., chdir=%r)', args, chdir)
|
|
assert isinstance(args, list)
|
|
|
|
if emulate_tty:
|
|
stderr = subprocess.STDOUT
|
|
else:
|
|
stderr = subprocess.PIPE
|
|
|
|
proc = subprocess.Popen(
|
|
args=args,
|
|
stdout=subprocess.PIPE,
|
|
stderr=stderr,
|
|
stdin=subprocess.PIPE,
|
|
cwd=chdir,
|
|
)
|
|
stdout, stderr = proc.communicate(in_data)
|
|
|
|
if emulate_tty:
|
|
stdout = stdout.replace(b'\n', b'\r\n')
|
|
return proc.returncode, stdout, stderr or ''
|
|
|
|
|
|
def exec_command(cmd, in_data='', chdir=None, shell=None, emulate_tty=False):
|
|
"""
|
|
Run a command in a subprocess, emulating the argument handling behaviour of
|
|
SSH.
|
|
|
|
:param bytes cmd:
|
|
String command line, passed to user's shell.
|
|
:param bytes in_data:
|
|
Optional standard input for the command.
|
|
:return:
|
|
(return code, stdout bytes, stderr bytes)
|
|
"""
|
|
assert isinstance(cmd, mitogen.core.UnicodeType)
|
|
return exec_args(
|
|
args=[get_user_shell(), '-c', cmd],
|
|
in_data=in_data,
|
|
chdir=chdir,
|
|
shell=shell,
|
|
emulate_tty=emulate_tty,
|
|
)
|
|
|
|
|
|
def read_path(path):
|
|
"""
|
|
Fetch the contents of a filesystem `path` as bytes.
|
|
"""
|
|
return open(path, 'rb').read()
|
|
|
|
|
|
def set_fd_owner(fd, owner, group=None):
|
|
if owner:
|
|
uid = pwd.getpwnam(owner).pw_uid
|
|
else:
|
|
uid = os.geteuid()
|
|
|
|
if group:
|
|
gid = grp.getgrnam(group).gr_gid
|
|
else:
|
|
gid = os.getegid()
|
|
|
|
os.fchown(fd, (uid, gid))
|
|
|
|
|
|
def write_path(path, s, owner=None, group=None, mode=None,
|
|
utimes=None, sync=False):
|
|
"""
|
|
Writes bytes `s` to a filesystem `path`.
|
|
"""
|
|
path = os.path.abspath(path)
|
|
fd, tmp_path = tempfile.mkstemp(suffix='.tmp',
|
|
prefix='.ansible_mitogen_transfer-',
|
|
dir=os.path.dirname(path))
|
|
fp = os.fdopen(fd, 'wb', mitogen.core.CHUNK_SIZE)
|
|
LOG.debug('write_path(path=%r) temporary file: %s', path, tmp_path)
|
|
|
|
try:
|
|
try:
|
|
if mode:
|
|
os.fchmod(fp.fileno(), mode)
|
|
if owner or group:
|
|
set_fd_owner(fp.fileno(), owner, group)
|
|
fp.write(s)
|
|
finally:
|
|
fp.close()
|
|
|
|
if sync:
|
|
os.fsync(fp.fileno())
|
|
os.rename(tmp_path, path)
|
|
except BaseException:
|
|
os.unlink(tmp_path)
|
|
raise
|
|
|
|
if utimes:
|
|
os.utime(path, utimes)
|
|
|
|
|
|
CHMOD_CLAUSE_PAT = re.compile(r'([uoga]*)([+\-=])([ugo]|[rwx]*)')
|
|
CHMOD_MASKS = {
|
|
'u': stat.S_IRWXU,
|
|
'g': stat.S_IRWXG,
|
|
'o': stat.S_IRWXO,
|
|
'a': (stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO),
|
|
}
|
|
CHMOD_BITS = {
|
|
'u': {'r': stat.S_IRUSR, 'w': stat.S_IWUSR, 'x': stat.S_IXUSR},
|
|
'g': {'r': stat.S_IRGRP, 'w': stat.S_IWGRP, 'x': stat.S_IXGRP},
|
|
'o': {'r': stat.S_IROTH, 'w': stat.S_IWOTH, 'x': stat.S_IXOTH},
|
|
'a': {
|
|
'r': (stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH),
|
|
'w': (stat.S_IWUSR | stat.S_IWGRP | stat.S_IWOTH),
|
|
'x': (stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)
|
|
}
|
|
}
|
|
|
|
|
|
def apply_mode_spec(spec, mode):
|
|
"""
|
|
Given a symbolic file mode change specification in the style of chmod(1)
|
|
`spec`, apply changes in the specification to the numeric file mode `mode`.
|
|
"""
|
|
for clause in spec.split(','):
|
|
match = CHMOD_CLAUSE_PAT.match(clause)
|
|
who, op, perms = match.groups()
|
|
for ch in who or 'a':
|
|
mask = CHMOD_MASKS[ch]
|
|
bits = CHMOD_BITS[ch]
|
|
cur_perm_bits = mode & mask
|
|
new_perm_bits = functools.reduce(operator.or_, (bits[p] for p in perms), 0)
|
|
mode &= ~mask
|
|
if op == '=':
|
|
mode |= new_perm_bits
|
|
elif op == '+':
|
|
mode |= new_perm_bits | cur_perm_bits
|
|
else:
|
|
mode |= cur_perm_bits & ~new_perm_bits
|
|
return mode
|
|
|
|
|
|
def set_file_mode(path, spec):
|
|
"""
|
|
Update the permissions of a file using the same syntax as chmod(1).
|
|
"""
|
|
mode = os.stat(path).st_mode
|
|
|
|
if spec.isdigit():
|
|
new_mode = int(spec, 8)
|
|
else:
|
|
new_mode = apply_mode_spec(spec, mode)
|
|
|
|
os.chmod(path, new_mode)
|