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Mini Shell
Mini Shell
"""
This program is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License,
or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
Copyright © 2019 Cloud Linux Software Inc.
This software is also available under ImunifyAV commercial license,
see <https://www.imunify360.com/legal/eula>
Config providers that work with files"""
import json
import logging
import os
import pwd
from abc import abstractmethod
from contextlib import suppress
from textwrap import dedent
from typing import Mapping, Optional, Protocol
import yaml
from defence360agent.utils import atomic_rewrite
logger = logging.getLogger(__name__)
# Don't read config if its file is larger than this.
_MAX_CONFIG_SIZE = 1 << 20 # 1MiB
class IConfigProvider(Protocol):
@abstractmethod
def read_config_file(
self, force_read: bool = False, ignore_errors: bool = True
):
raise NotImplementedError
@abstractmethod
def write_config_file(self, config: Mapping) -> None:
raise NotImplementedError
@abstractmethod
def modified_since(self, timestamp: Optional[float]) -> bool:
raise NotImplementedError
class ConfigError(Exception):
pass
class JsonMessage:
"""Pretty-print given *obj* as JSON.
To be used for logging. Example:
logging.info("object: %s", JsonMessage(obj))
"""
def __init__(self, obj):
self._obj = obj
def __str__(self):
return json.dumps(self._obj, sort_keys=True)
def diff_section(prev_section: Optional[dict], section: Optional[dict]):
"""Return difference between config sections."""
prev_section = prev_section or {}
section = section or {}
removed_settings = prev_section.keys() - section.keys()
added_settings = section.keys() - prev_section.keys()
return {
"-": {v: prev_section[v] for v in removed_settings},
"+": {v: section[v] for v in added_settings},
# modified settings
"?": {
v: (prev_section[v], section[v])
for v in (prev_section.keys() & section.keys())
if prev_section[v] != section[v]
},
}
def diff_config(prev_conf: dict, conf: dict):
"""Compare *prev_conf* with the current *conf*."""
removed_sections = prev_conf.keys() - conf.keys()
yield {section: prev_conf[section] for section in removed_sections}
added_sections = conf.keys() - prev_conf.keys()
yield {section: conf[section] for section in added_sections}
# changed sections
yield {
section: diff_section(prev_conf[section], conf[section])
for section in (prev_conf.keys() & conf.keys())
if prev_conf[section] != conf[section]
}
def exclude_equals(*, main_conf: dict, base_conf: dict) -> dict:
"""
Return dict derived from *main_conf* excluding parts
that are equal in *base_conf*.
For example,
>>> base_conf = {
"SECTION1": {"OPTION1": "default", "OPTION2": "default"},
"SECTION2": {"OPTION1": "default"}
}
>>> main_conf = {
"SECTION1": {"OPTION1": "value", "OPTION2": "default"},
"SECTION2": {"OPTION1": "default"}
}
>>>
>>> exclude_equals(main_conf=main_conf, base_conf=base_conf)
{'SECTION1': {'OPTION1': 'value'}}
>>>
"""
_, added, changed = diff_config(base_conf, main_conf)
result = {}
for section, value in main_conf.items():
if section in added.keys():
result[section] = value
if section in changed.keys():
result.setdefault(section, {}).update(
changed[section]["+"]
)
result.setdefault(section, {}).update(
{k: v[1] for k, v in changed[section]["?"].items()}
)
return result
class ConfigReader:
"""
ConfigFile file for settings page.
Location config file is PATH
"""
def __init__(self, path, disclaimer="", permissions=None):
self.path = path
self.disclaimer = disclaimer
self.permissions = permissions
def __repr__(self):
return "<{classname}({path})>".format(
classname=self.__class__.__qualname__, path=self.path
)
def __str__(self):
return f"ConfigReader at {self.path}"
def read_config_file(
self, force_read: bool = False, ignore_errors: bool = True
) -> dict:
"""Read config file into memory.
Raises ConfigError.
"""
try:
if os.path.getsize(self.path) > _MAX_CONFIG_SIZE:
raise ConfigError("Config file is too large")
filename = self.path
with open(filename, "r") as config_file:
logger.info("Reading config file %s", filename)
text = config_file.read()
except UnicodeDecodeError as e:
raise ConfigError("Unable to decode config file") from e
except FileNotFoundError:
return {}
try:
config = yaml.safe_load(text)
except yaml.YAMLError as e:
raise ConfigError(
"Imunify360 config is not valid YAML document"
) from e
if config is None:
return {}
if not isinstance(config, dict):
raise ConfigError(
"Imunify360 config is invalid or empty"
": path={!r}, text={!r}".format(self.path, text)
)
return config
def _pre_write(self):
pass
def _post_write(self):
pass
def write_config_file(self, config) -> None:
self._pre_write()
config_text = ""
if self.disclaimer:
config_text += dedent(self.disclaimer)
config_text += "\n"
config_text += yaml.dump(config, default_flow_style=False)
atomic_rewrite(self.path, config_text, backup=False,
permissions=self.permissions)
self._post_write()
def modified_since(self, timestamp: Optional[float]) -> bool:
return True
class CachedConfigReader(ConfigReader):
def __init__(self, path, disclaimer="", permissions=None):
super().__init__(path, disclaimer)
self.mtime: Optional[float] = None
self.size: Optional[float] = None
self._config = {}
self.permissions = permissions
def __str__(self):
return (
"{classname} <'{path}', modified at {mtime}, {size} bytes>".format(
classname=self.__class__.__qualname__,
path=self.path,
mtime=self.mtime,
size=self.size,
)
)
def read_config_file(
self, force_read: bool = False, ignore_errors: bool = True
):
""" Update config if config file is modified """
if self.modified_since(self.mtime) or force_read:
prev_config = self._config
try:
self._config = super().read_config_file()
except ConfigError as error:
if not ignore_errors:
raise
logger.exception(
"Intentionally ignoring known config error: %s", error
)
logger.warning(
"%s is invalid, using previous settings: %s",
self,
JsonMessage(self._config),
)
else:
if self.mtime is not None: # don't log on startup
diffs = list(diff_config(prev_config, self._config))
if any(diffs):
# content has changed, log it
logger.info(
"%s modified: removed=%s, added=%s, changed=%s",
self,
*map(JsonMessage, diffs),
)
try:
stat = os.stat(self.path)
self.mtime = stat.st_mtime
self.size = stat.st_size
except FileNotFoundError:
self.mtime = 0.0
self.size = 0.0
return self._config
def modified_since(self, timestamp: Optional[float]) -> bool:
"""Whether the config has updated since *timestamp*.
(as defined by its last modification time and size)
:param timestamp: None means that the file has never been read before
"""
# On startup consider timestamp to be None
if timestamp is None:
timestamp = 0.0
try:
stat = os.stat(self.path)
except FileNotFoundError:
st_mtime, st_size = 0.0, 0.0
else:
st_mtime, st_size = stat.st_mtime, stat.st_size
return st_mtime > timestamp or st_size != self.size
class UserConfigReader(CachedConfigReader):
def __init__(self, path, username):
super().__init__(path)
self.username = username
def __str__(self):
return f"Config of user {self.username}"
def _pre_write(self):
confdir = os.path.dirname(self.path)
with suppress(FileExistsError):
os.mkdir(os.path.dirname(self.path))
os.chown(confdir, 0, pwd.getpwnam(self.username).pw_gid)
os.chmod(confdir, 0o750)
def _post_write(self):
os.chown(self.path, 0, pwd.getpwnam(self.username).pw_gid)
os.chmod(self.path, 0o640)
Zerion Mini Shell 1.0