# Copyright 2011-2019, Damian Johnson and The Tor Project
# See LICENSE for licensing information
"""
Handlers for text configuration files. Configurations are simple string to
string mappings, with the configuration files using the following rules...
* the key/value is separated by a space
* anything after a '#' is ignored as a comment
* excess whitespace is trimmed
* empty lines are ignored
* multi-line values can be defined by following the key with lines starting
with a '|'
For instance...
::
# This is my sample config
user.name Galen
user.password yabba1234 # here's an inline comment
user.notes takes a fancy to pepperjack cheese
blankEntry.example
msg.greeting
|Multi-line message exclaiming of the
|wonder and awe that is pepperjack!
... would be loaded as...
::
config = {
'user.name': 'Galen',
'user.password': 'yabba1234',
'user.notes': 'takes a fancy to pepperjack cheese',
'blankEntry.example': '',
'msg.greeting': 'Multi-line message exclaiming of the\\nwonder and awe that is pepperjack!',
}
Configurations are managed via the :class:`~stem.util.conf.Config` class. The
:class:`~stem.util.conf.Config` can be be used directly with its
:func:`~stem.util.conf.Config.get` and :func:`~stem.util.conf.Config.set`
methods, but usually modules will want a local dictionary with just the
configurations that it cares about.
To do this use the :func:`~stem.util.conf.config_dict` function. For example...
::
import getpass
from stem.util import conf, connection
def config_validator(key, value):
if key == 'timeout':
# require at least a one second timeout
return max(1, value)
elif key == 'endpoint':
if not connection.is_valid_ipv4_address(value):
raise ValueError("'%s' isn't a valid IPv4 address" % value)
elif key == 'port':
if not connection.is_valid_port(value):
raise ValueError("'%s' isn't a valid port" % value)
elif key == 'retries':
# negative retries really don't make sense
return max(0, value)
CONFIG = conf.config_dict('ssh_login', {
'username': getpass.getuser(),
'password': '',
'timeout': 10,
'endpoint': '263.12.8.0',
'port': 22,
'reconnect': False,
'retries': 3,
}, config_validator)
There's several things going on here so lets take it step by step...
* The :func:`~stem.util.conf.config_dict` provides a dictionary that's bound
to a given configuration. If the "ssh_proxy_config" configuration changes
then so will the contents of CONFIG.
* The dictionary we're passing to :func:`~stem.util.conf.config_dict` provides
two important pieces of information: default values and their types. See the
Config's :func:`~stem.util.conf.Config.get` method for how these type
inferences work.
* The config_validator is a hook we're adding to make sure CONFIG only gets
values we think are valid. In this case it ensures that our timeout value
is at least one second, and rejects endpoints or ports that are invalid.
Now lets say our user has the following configuration file...
::
username waddle_doo
password jabberwocky
timeout -15
port 9000000
retries lots
reconnect true
logging debug
... and we load it as follows...
::
>>> from stem.util import conf
>>> our_config = conf.get_config('ssh_login')
>>> our_config.load('/home/atagar/user_config')
>>> print CONFIG # doctest: +SKIP
{
"username": "waddle_doo",
"password": "jabberwocky",
"timeout": 1,
"endpoint": "263.12.8.0",
"port": 22,
"reconnect": True,
"retries": 3,
}
Here's an expanation of what happened...
* the username, password, and reconnect attributes took the values in the
configuration file
* the 'config_validator' we added earlier allows for a minimum timeout of one
and rejected the invalid port (with a log message)
* we weren't able to convert the retries' "lots" value to an integer so it kept
its default value and logged a warning
* the user didn't supply an endpoint so that remained unchanged
* our CONFIG didn't have a 'logging' attribute so it was ignored
**Module Overview:**
::
config_dict - provides a dictionary that's kept in sync with our config
get_config - singleton for getting configurations
uses_settings - provides an annotation for functions that use configurations
parse_enum_csv - helper funcion for parsing confguration entries for enums
Config - Custom configuration
|- load - reads a configuration file
|- save - writes the current configuration to a file
|- clear - empties our loaded configuration contents
|- add_listener - notifies the given listener when an update occurs
|- clear_listeners - removes any attached listeners
|- keys - provides keys in the loaded configuration
|- set - sets the given key/value pair
|- unused_keys - provides keys that have never been requested
|- get - provides the value for a given key, with type inference
+- get_value - provides the value for a given key as a string
"""
import inspect
import os
import threading
import stem.prereq
from stem.util import log
try:
# added in python 2.7
from collections import OrderedDict
except ImportError:
from stem.util.ordereddict import OrderedDict
CONFS = {} # mapping of identifier to singleton instances of configs
class _SyncListener(object):
def __init__(self, config_dict, interceptor):
self.config_dict = config_dict
self.interceptor = interceptor
def update(self, config, key):
if key in self.config_dict:
new_value = config.get(key, self.config_dict[key])
if new_value == self.config_dict[key]:
return # no change
if self.interceptor:
interceptor_value = self.interceptor(key, new_value)
if interceptor_value:
new_value = interceptor_value
self.config_dict[key] = new_value
[docs]def config_dict(handle, conf_mappings, handler = None):
"""
Makes a dictionary that stays synchronized with a configuration.
This takes a dictionary of 'config_key => default_value' mappings and
changes the values to reflect our current configuration. This will leave
the previous values alone if...
* we don't have a value for that config_key
* we can't convert our value to be the same type as the default_value
If a handler is provided then this is called just prior to assigning new
values to the config_dict. The handler function is expected to accept the
(key, value) for the new values and return what we should actually insert
into the dictionary. If this returns None then the value is updated as
normal.
For more information about how we convert types see our
:func:`~stem.util.conf.Config.get` method.
**The dictionary you get from this is manged by the Config class and should
be treated as being read-only.**
:param str handle: unique identifier for a config instance
:param dict conf_mappings: config key/value mappings used as our defaults
:param functor handler: function referred to prior to assigning values
"""
selected_config = get_config(handle)
selected_config.add_listener(_SyncListener(conf_mappings, handler).update)
return conf_mappings
[docs]def get_config(handle):
"""
Singleton constructor for configuration file instances. If a configuration
already exists for the handle then it's returned. Otherwise a fresh instance
is constructed.
:param str handle: unique identifier used to access this config instance
"""
if handle not in CONFS:
CONFS[handle] = Config()
return CONFS[handle]
[docs]def uses_settings(handle, path, lazy_load = True):
"""
Provides a function that can be used as a decorator for other functions that
require settings to be loaded. Functions with this decorator will be provided
with the configuration as its 'config' keyword argument.
.. versionchanged:: 1.3.0
Omits the 'config' argument if the funcion we're decorating doesn't accept
it.
::
uses_settings = stem.util.conf.uses_settings('my_app', '/path/to/settings.cfg')
@uses_settings
def my_function(config):
print 'hello %s!' % config.get('username', '')
:param str handle: hande for the configuration
:param str path: path where the configuration should be loaded from
:param bool lazy_load: loads the configuration file when the decorator is
used if true, otherwise it's loaded right away
:returns: **function** that can be used as a decorator to provide the
configuration
:raises: **IOError** if we fail to read the configuration file, if
**lazy_load** is true then this arises when we use the decorator
"""
config = get_config(handle)
if not lazy_load and not config._settings_loaded:
config.load(path)
config._settings_loaded = True
def decorator(func):
def wrapped(*args, **kwargs):
if lazy_load and not config._settings_loaded:
config.load(path)
config._settings_loaded = True
if 'config' in inspect.getargspec(func).args:
return func(*args, config = config, **kwargs)
else:
return func(*args, **kwargs)
return wrapped
return decorator
[docs]def parse_enum(key, value, enumeration):
"""
Provides the enumeration value for a given key. This is a case insensitive
lookup and raises an exception if the enum key doesn't exist.
:param str key: configuration key being looked up
:param str value: value to be parsed
:param stem.util.enum.Enum enumeration: enumeration the values should be in
:returns: enumeration value
:raises: **ValueError** if the **value** isn't among the enumeration keys
"""
return parse_enum_csv(key, value, enumeration, 1)[0]
[docs]def parse_enum_csv(key, value, enumeration, count = None):
"""
Parses a given value as being a comma separated listing of enumeration keys,
returning the corresponding enumeration values. This is intended to be a
helper for config handlers. The checks this does are case insensitive.
The **count** attribute can be used to make assertions based on the number of
values. This can be...
* None to indicate that there's no restrictions.
* An int to indicate that we should have this many values.
* An (int, int) tuple to indicate the range that values can be in. This range
is inclusive and either can be None to indicate the lack of a lower or
upper bound.
:param str key: configuration key being looked up
:param str value: value to be parsed
:param stem.util.enum.Enum enumeration: enumeration the values should be in
:param int,tuple count: validates that we have this many items
:returns: list with the enumeration values
:raises: **ValueError** if the count assertion fails or the **value** entries
don't match the enumeration keys
"""
values = [val.upper().strip() for val in value.split(',')]
if values == ['']:
return []
if count is None:
pass # no count validateion checks to do
elif isinstance(count, int):
if len(values) != count:
raise ValueError("Config entry '%s' is expected to be %i comma separated values, got '%s'" % (key, count, value))
elif isinstance(count, tuple) and len(count) == 2:
minimum, maximum = count
if minimum is not None and len(values) < minimum:
raise ValueError("Config entry '%s' must have at least %i comma separated values, got '%s'" % (key, minimum, value))
if maximum is not None and len(values) > maximum:
raise ValueError("Config entry '%s' can have at most %i comma separated values, got '%s'" % (key, maximum, value))
else:
raise ValueError("The count must be None, an int, or two value tuple. Got '%s' (%s)'" % (count, type(count)))
result = []
enum_keys = [k.upper() for k in list(enumeration.keys())]
enum_values = list(enumeration)
for val in values:
if val in enum_keys:
result.append(enum_values[enum_keys.index(val)])
else:
raise ValueError("The '%s' entry of config entry '%s' wasn't in the enumeration (expected %s)" % (val, key, ', '.join(enum_keys)))
return result
[docs]class Config(object):
"""
Handler for easily working with custom configurations, providing persistence
to and from files. All operations are thread safe.
**Example usage:**
User has a file at '/home/atagar/myConfig' with...
::
destination.ip 1.2.3.4
destination.port blarg
startup.run export PATH=$PATH:~/bin
startup.run alias l=ls
And they have a script with...
::
from stem.util import conf
# Configuration values we'll use in this file. These are mappings of
# configuration keys to the default values we'll use if the user doesn't
# have something different in their config file (or it doesn't match this
# type).
ssh_config = conf.config_dict('ssh_login', {
'login.user': 'atagar',
'login.password': 'pepperjack_is_awesome!',
'destination.ip': '127.0.0.1',
'destination.port': 22,
'startup.run': [],
})
# Makes an empty config instance with the handle of 'ssh_login'. This is
# a singleton so other classes can fetch this same configuration from
# this handle.
user_config = conf.get_config('ssh_login')
# Loads the user's configuration file, warning if this fails.
try:
user_config.load("/home/atagar/myConfig")
except IOError as exc:
print "Unable to load the user's config: %s" % exc
# This replace the contents of ssh_config with the values from the user's
# config file if...
#
# * the key is present in the config file
# * we're able to convert the configuration file's value to the same type
# as what's in the mapping (see the Config.get() method for how these
# type inferences work)
#
# For instance in this case...
#
# * the login values are left alone because they aren't in the user's
# config file
#
# * the 'destination.port' is also left with the value of 22 because we
# can't turn "blarg" into an integer
#
# The other values are replaced, so ssh_config now becomes...
#
# {'login.user': 'atagar',
# 'login.password': 'pepperjack_is_awesome!',
# 'destination.ip': '1.2.3.4',
# 'destination.port': 22,
# 'startup.run': ['export PATH=$PATH:~/bin', 'alias l=ls']}
#
# Information for what values fail to load and why are reported to
# 'stem.util.log'.
.. versionchanged:: 1.7.0
Class can now be used as a dictionary.
"""
def __init__(self):
self._path = None # location we last loaded from or saved to
self._contents = OrderedDict() # configuration key/value pairs
self._listeners = [] # functors to be notified of config changes
# used for accessing _contents
self._contents_lock = threading.RLock()
# keys that have been requested (used to provide unused config contents)
self._requested_keys = set()
# flag to support lazy loading in uses_settings()
self._settings_loaded = False
[docs] def load(self, path = None, commenting = True):
"""
Reads in the contents of the given path, adding its configuration values
to our current contents. If the path is a directory then this loads each
of the files, recursively.
.. versionchanged:: 1.3.0
Added support for directories.
.. versionchanged:: 1.3.0
Added the **commenting** argument.
.. versionchanged:: 1.6.0
Avoid loading vim swap files.
:param str path: file or directory path to be loaded, this uses the last
loaded path if not provided
:param bool commenting: ignore line content after a '#' if **True**, read
otherwise
:raises:
* **IOError** if we fail to read the file (it doesn't exist, insufficient
permissions, etc)
* **ValueError** if no path was provided and we've never been provided one
"""
if path:
self._path = path
elif not self._path:
raise ValueError('Unable to load configuration: no path provided')
if os.path.isdir(self._path):
for root, dirnames, filenames in os.walk(self._path):
for filename in filenames:
if filename.endswith('.swp'):
continue # vim swap file
self.load(os.path.join(root, filename))
return
with open(self._path, 'r') as config_file:
read_contents = config_file.readlines()
with self._contents_lock:
while read_contents:
line = read_contents.pop(0)
# strips any commenting or excess whitespace
comment_start = line.find('#') if commenting else -1
if comment_start != -1:
line = line[:comment_start]
line = line.strip()
# parse the key/value pair
if line:
if ' ' in line:
key, value = line.split(' ', 1)
self.set(key, value.strip(), False)
else:
# this might be a multi-line entry, try processing it as such
multiline_buffer = []
while read_contents and read_contents[0].lstrip().startswith('|'):
content = read_contents.pop(0).lstrip()[1:] # removes '\s+|' prefix
content = content.rstrip('\n') # trailing newline
multiline_buffer.append(content)
if multiline_buffer:
self.set(line, '\n'.join(multiline_buffer), False)
else:
self.set(line, '', False) # default to a key => '' mapping
[docs] def save(self, path = None):
"""
Saves configuration contents to disk. If a path is provided then it
replaces the configuration location that we track.
:param str path: location to be saved to
:raises:
* **IOError** if we fail to save the file (insufficient permissions, etc)
* **ValueError** if no path was provided and we've never been provided one
"""
if path:
self._path = path
elif not self._path:
raise ValueError('Unable to save configuration: no path provided')
with self._contents_lock:
if not os.path.exists(os.path.dirname(self._path)):
os.makedirs(os.path.dirname(self._path))
with open(self._path, 'w') as output_file:
for entry_key in self.keys():
for entry_value in self.get_value(entry_key, multiple = True):
# check for multi line entries
if '\n' in entry_value:
entry_value = '\n|' + entry_value.replace('\n', '\n|')
output_file.write('%s %s\n' % (entry_key, entry_value))
[docs] def clear(self):
"""
Drops the configuration contents and reverts back to a blank, unloaded
state.
"""
with self._contents_lock:
self._contents.clear()
self._requested_keys = set()
[docs] def add_listener(self, listener, backfill = True):
"""
Registers the function to be notified of configuration updates. Listeners
are expected to be functors which accept (config, key).
:param functor listener: function to be notified when our configuration is changed
:param bool backfill: calls the function with our current values if **True**
"""
with self._contents_lock:
self._listeners.append(listener)
if backfill:
for key in self.keys():
listener(self, key)
[docs] def clear_listeners(self):
"""
Removes all attached listeners.
"""
self._listeners = []
[docs] def keys(self):
"""
Provides all keys in the currently loaded configuration.
:returns: **list** if strings for the configuration keys we've loaded
"""
return list(self._contents.keys())
[docs] def unused_keys(self):
"""
Provides the configuration keys that have never been provided to a caller
via :func:`~stem.util.conf.config_dict` or the
:func:`~stem.util.conf.Config.get` and
:func:`~stem.util.conf.Config.get_value` methods.
:returns: **set** of configuration keys we've loaded but have never been requested
"""
return set(self.keys()).difference(self._requested_keys)
[docs] def set(self, key, value, overwrite = True):
"""
Appends the given key/value configuration mapping, behaving the same as if
we'd loaded this from a configuration file.
.. versionchanged:: 1.5.0
Allow removal of values by overwriting with a **None** value.
:param str key: key for the configuration mapping
:param str,list value: value we're setting the mapping to
:param bool overwrite: replaces the previous value if **True**, otherwise
the values are appended
"""
with self._contents_lock:
unicode_type = str if stem.prereq.is_python_3() else unicode
if value is None:
if overwrite and key in self._contents:
del self._contents[key]
else:
pass # no value so this is a no-op
elif isinstance(value, (bytes, unicode_type)):
if not overwrite and key in self._contents:
self._contents[key].append(value)
else:
self._contents[key] = [value]
for listener in self._listeners:
listener(self, key)
elif isinstance(value, (list, tuple)):
if not overwrite and key in self._contents:
self._contents[key] += value
else:
self._contents[key] = value
for listener in self._listeners:
listener(self, key)
else:
raise ValueError("Config.set() only accepts str (bytes or unicode), list, or tuple. Provided value was a '%s'" % type(value))
[docs] def get(self, key, default = None):
"""
Fetches the given configuration, using the key and default value to
determine the type it should be. Recognized inferences are:
* **default is a boolean => boolean**
* values are case insensitive
* provides the default if the value isn't "true" or "false"
* **default is an integer => int**
* provides the default if the value can't be converted to an int
* **default is a float => float**
* provides the default if the value can't be converted to a float
* **default is a list => list**
* string contents for all configuration values with this key
* **default is a tuple => tuple**
* string contents for all configuration values with this key
* **default is a dictionary => dict**
* values without "=>" in them are ignored
* values are split into key/value pairs on "=>" with extra whitespace
stripped
:param str key: config setting to be fetched
:param default object: value provided if no such key exists or fails to be converted
:returns: given configuration value with its type inferred with the above rules
"""
is_multivalue = isinstance(default, (list, tuple, dict))
val = self.get_value(key, default, is_multivalue)
if val == default:
return val # don't try to infer undefined values
if isinstance(default, bool):
if val.lower() == 'true':
val = True
elif val.lower() == 'false':
val = False
else:
log.debug("Config entry '%s' is expected to be a boolean, defaulting to '%s'" % (key, str(default)))
val = default
elif isinstance(default, int):
try:
val = int(val)
except ValueError:
log.debug("Config entry '%s' is expected to be an integer, defaulting to '%i'" % (key, default))
val = default
elif isinstance(default, float):
try:
val = float(val)
except ValueError:
log.debug("Config entry '%s' is expected to be a float, defaulting to '%f'" % (key, default))
val = default
elif isinstance(default, list):
val = list(val) # make a shallow copy
elif isinstance(default, tuple):
val = tuple(val)
elif isinstance(default, dict):
val_map = OrderedDict()
for entry in val:
if '=>' in entry:
entry_key, entry_val = entry.split('=>', 1)
val_map[entry_key.strip()] = entry_val.strip()
else:
log.debug('Ignoring invalid %s config entry (expected a mapping, but "%s" was missing "=>")' % (key, entry))
val = val_map
return val
[docs] def get_value(self, key, default = None, multiple = False):
"""
This provides the current value associated with a given key.
:param str key: config setting to be fetched
:param object default: value provided if no such key exists
:param bool multiple: provides back a list of all values if **True**,
otherwise this returns the last loaded configuration value
:returns: **str** or **list** of string configuration values associated
with the given key, providing the default if no such key exists
"""
with self._contents_lock:
if key in self._contents:
self._requested_keys.add(key)
if multiple:
return self._contents[key]
else:
return self._contents[key][-1]
else:
message_id = 'stem.util.conf.missing_config_key_%s' % key
log.log_once(message_id, log.TRACE, "config entry '%s' not found, defaulting to '%s'" % (key, default))
return default
def __getitem__(self, key):
with self._contents_lock:
return self._contents[key]
