tahoe-lafs/src/allmydata/util/configutil.py
2020-05-04 21:59:15 -06:00

113 lines
3.7 KiB
Python

from ConfigParser import SafeConfigParser
import attr
class UnknownConfigError(Exception):
"""
An unknown config item was found.
This is possibly raised by validate_config()
"""
def get_config(tahoe_cfg):
config = SafeConfigParser()
with open(tahoe_cfg, "rb") as f:
# Skip any initial Byte Order Mark. Since this is an ordinary file, we
# don't need to handle incomplete reads, and can assume seekability.
if f.read(3) != '\xEF\xBB\xBF':
f.seek(0)
config.readfp(f)
return config
def set_config(config, section, option, value):
if not config.has_section(section):
config.add_section(section)
config.set(section, option, value)
assert config.get(section, option) == value
def write_config(tahoe_cfg, config):
with open(tahoe_cfg, "wb") as f:
config.write(f)
def validate_config(fname, cfg, valid_config):
"""
:param ValidConfiguration valid_config: The definition of a valid
configuration.
:raises UnknownConfigError: if there are any unknown sections or config
values.
"""
for section in cfg.sections():
if not valid_config.is_valid_section(section):
raise UnknownConfigError(
"'{fname}' contains unknown section [{section}]".format(
fname=fname,
section=section,
)
)
for option in cfg.options(section):
if not valid_config.is_valid_item(section, option):
raise UnknownConfigError(
"'{fname}' section [{section}] contains unknown option '{option}'".format(
fname=fname,
section=section,
option=option,
)
)
@attr.s
class ValidConfiguration(object):
"""
:ivar dict[bytes, tuple[bytes]] _static_valid_sections: A mapping from
valid section names to valid items in those sections.
:ivar _is_valid_section: A callable which accepts a section name as bytes
and returns True if that section name is valid, False otherwise.
:ivar _is_valid_item: A callable which accepts a section name as bytes and
an item name as bytes and returns True if that section, item pair is
valid, False otherwise.
"""
_static_valid_sections = attr.ib()
_is_valid_section = attr.ib(default=lambda section_name: False)
_is_valid_item = attr.ib(default=lambda section_name, item_name: False)
def is_valid_section(self, section_name):
"""
:return: True if the given section name is valid, False otherwise.
"""
return (
section_name in self._static_valid_sections or
self._is_valid_section(section_name)
)
def is_valid_item(self, section_name, item_name):
"""
:return: True if the given section name, ite name pair is valid, False
otherwise.
"""
return (
item_name in self._static_valid_sections.get(section_name, ()) or
self._is_valid_item(section_name, item_name)
)
def update(self, valid_config):
static_valid_sections = self._static_valid_sections.copy()
static_valid_sections.update(valid_config._static_valid_sections)
return ValidConfiguration(
static_valid_sections,
_either(self._is_valid_section, valid_config._is_valid_section),
_either(self._is_valid_item, valid_config._is_valid_item),
)
def _either(f, g):
"""
:return: A function which returns True if either f or g returns True.
"""
return lambda *a, **kw: f(*a, **kw) or g(*a, **kw)