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# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# Copyright 2011 Justin Santa Barbara
# Copyright 2018 Michael Still and Aptira
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
# This module is utility methods that privsep depends on. Privsep isn't allowed
# to depend on anything outside the privsep directory, so these need to be
# here. That said, other parts of nova can call into these utilities if
# needed.
import errno
import mmap
import os
import random
import sys
from oslo_log import log as logging
from oslo_utils import excutils
import nova.privsep
# NOTE(mriedem): Avoid importing nova.utils since that can cause a circular
# import with the privsep code. In fact, avoid importing anything outside
# of nova/privsep/ if possible.
LOG = logging.getLogger(__name__)
def generate_random_string():
return str(random.randint(0, sys.maxsize))
def supports_direct_io(dirpath):
if not hasattr(os, 'O_DIRECT'):
LOG.debug("This python runtime does not support direct I/O")
return False
# Use a random filename to avoid issues with $dirpath being on shared
# storage.
file_name = "%s.%s" % (".directio.test", generate_random_string())
testfile = os.path.join(dirpath, file_name)
hasDirectIO = True
fd = None
try:
fd = os.open(testfile, os.O_CREAT | os.O_WRONLY | os.O_DIRECT)
# Check is the write allowed with 4096 byte alignment
align_size = 4096
m = mmap.mmap(-1, align_size)
m.write(b"x" * align_size)
os.write(fd, m)
LOG.debug("Path '%(path)s' supports direct I/O",
{'path': dirpath})
except OSError as e:
if e.errno in (errno.EINVAL, errno.ENOENT):
LOG.debug("Path '%(path)s' does not support direct I/O: "
"'%(ex)s'", {'path': dirpath, 'ex': e})
hasDirectIO = False
else:
with excutils.save_and_reraise_exception():
LOG.error("Error on '%(path)s' while checking "
"direct I/O: '%(ex)s'",
{'path': dirpath, 'ex': e})
except Exception as e:
with excutils.save_and_reraise_exception():
LOG.error("Error on '%(path)s' while checking direct I/O: "
"'%(ex)s'", {'path': dirpath, 'ex': e})
finally:
# ensure unlink(filepath) will actually remove the file by deleting
# the remaining link to it in close(fd)
if fd is not None:
os.close(fd)
try:
os.unlink(testfile)
except Exception:
pass
return hasDirectIO
@nova.privsep.sys_admin_pctxt.entrypoint
def kill(pid, signal):
os.kill(pid, signal)
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