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""" A plugin to provide helper classes and functions to templates """
import re
import imp
import sys
import logging
import Bcfg2.Server.Plugin
LOGGER = logging.getLogger(__name__)
MODULE_RE = re.compile(r'(?P<filename>(?P<module>[^\/]+)\.py)$')
def safe_module_name(module):
""" Munge the name of a TemplateHelper module to avoid collisions
with other Python modules. E.g., if someone has a helper named
'ldap.py', it should not be added to ``sys.modules`` as ``ldap``,
but rather as something more obscure. """
return '__TemplateHelper_%s' % module
class HelperModule(object):
""" Representation of a TemplateHelper module """
def __init__(self, name):
self.name = name
#: The name of the module as used by get_additional_data().
#: the name of the file with .py stripped off.
self._module_name = MODULE_RE.search(self.name).group('module')
#: The attributes exported by this module
self._attrs = []
def HandleEvent(self, event=None):
""" HandleEvent is called whenever the FAM registers an event.
:param event: The event object
:type event: Bcfg2.Server.FileMonitor.Event
:returns: None
"""
if event and event.code2str() not in ['exists', 'changed', 'created']:
return
try:
module = imp.load_source(safe_module_name(self._module_name),
self.name)
except: # pylint: disable=W0702
err = sys.exc_info()[1]
LOGGER.error("TemplateHelper: Failed to import %s: %s" %
(self.name, err))
return
if not hasattr(module, "__export__"):
LOGGER.error("TemplateHelper: %s has no __export__ list" %
self.name)
return
newattrs = []
for sym in module.__export__:
if sym not in self._attrs and hasattr(self, sym):
LOGGER.warning("TemplateHelper: %s: %s is a reserved keyword, "
"skipping export" % (self.name, sym))
continue
try:
setattr(self, sym, getattr(module, sym))
newattrs.append(sym)
except AttributeError:
LOGGER.warning("TemplateHelper: %s exports %s, but has no "
"such attribute" % (self.name, sym))
# remove old exports
for sym in set(self._attrs) - set(newattrs):
delattr(self, sym)
self._attrs = newattrs
class TemplateHelper(Bcfg2.Server.Plugin.Plugin,
Bcfg2.Server.Plugin.Connector,
Bcfg2.Server.Plugin.DirectoryBacked):
""" A plugin to provide helper classes and functions to templates """
__author__ = 'chris.a.st.pierre@gmail.com'
ignore = re.compile(r'^(\.#.*|.*~|\..*\.(sw[px])|.*\.py[co])$')
patterns = MODULE_RE
__child__ = HelperModule
def __init__(self, core, datastore):
Bcfg2.Server.Plugin.Plugin.__init__(self, core, datastore)
Bcfg2.Server.Plugin.Connector.__init__(self)
Bcfg2.Server.Plugin.DirectoryBacked.__init__(self, self.data)
def get_additional_data(self, _):
return dict([(h._module_name, h) # pylint: disable=W0212
for h in self.entries.values()])
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