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# 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.
"""Functions to address filesystem calls, particularly sysfs."""
import os
from oslo_log import log as logging
from nova import exception
LOG = logging.getLogger(__name__)
SYS = '/sys'
# NOTE(bauzas): this method is deliberately not wrapped in a privsep entrypoint
def read_sys(path: str) -> str:
"""Reads the content of a file in the sys filesystem.
:param path: relative or absolute. If relative, will be prefixed by /sys.
:returns: contents of that file.
:raises: nova.exception.FileNotFound if we can't read that file.
"""
try:
# The path can be absolute with a /sys prefix but that's fine.
with open(os.path.join(SYS, path), mode='r') as data:
return data.read()
except (OSError, ValueError) as exc:
raise exception.FileNotFound(file_path=path) from exc
# NOTE(bauzas): this method is deliberately not wrapped in a privsep entrypoint
# In order to correctly use it, you need to decorate the caller with a specific
# privsep entrypoint.
def write_sys(path: str, data: str) -> None:
"""Writes the content of a file in the sys filesystem with data.
:param path: relative or absolute. If relative, will be prefixed by /sys.
:param data: the data to write.
:returns: contents of that file.
:raises: nova.exception.FileNotFound if we can't write that file.
"""
try:
# The path can be absolute with a /sys prefix but that's fine.
with open(os.path.join(SYS, path), mode='w') as fd:
fd.write(data)
except (OSError, ValueError) as exc:
raise exception.FileNotFound(file_path=path) from exc
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