Server/Plugins/TemplateHelper: backported TemplateHelper from 1.3debian/1.2.3-5

3 files changed, 161 insertions, 0 deletions

diff --git a/debian/changelog b/debian/changelog
index d06347378..1d0ca0f58 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+bcfg2 (1.2.3-5) unstable; urgency=low
+
+  * Server/Plugins/TemplateHelper: backported TemplateHelper from 1.3
+
+ -- Alexander Sulfrian <alex@spline.inf.fu-berlin.de>  Fri, 22 Feb 2013 04:07:35 +0100
+
 bcfg2 (1.2.3-4) unstable; urgency=low
 
   * Client: always actions do not modify hosts
diff --git a/src/lib/Server/Plugins/TemplateHelper.py b/src/lib/Server/Plugins/TemplateHelper.py
new file mode 100644
index 000000000..3cdedb0ea
--- /dev/null
+++ b/src/lib/Server/Plugins/TemplateHelper.py
@@ -0,0 +1,154 @@
+""" A plugin to provide helper classes and functions to templates """
+
+import re
+import imp
+import sys
+import logging
+import Bcfg2.Server.Lint
+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, fam=None):
+        self.name = name
+        self.fam = fam
+
+        #: 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 """
+    name = 'TemplateHelper'
+    __author__ = 'chris.a.st.pierre@gmail.com'
+    ignore = re.compile("^(\.#.*|.*~|\\..*\\.(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, core.fam)
+
+    def get_additional_data(self, _):
+        return dict([(h._module_name, h)  # pylint: disable=W0212
+                     for h in self.entries.values()])
+
+
+class TemplateHelperLint(Bcfg2.Server.Lint.ServerPlugin):
+    """ find duplicate Pkgmgr entries with the same priority """
+    def __init__(self, *args, **kwargs):
+        Bcfg2.Server.Lint.ServerPlugin.__init__(self, *args, **kwargs)
+        self.reserved_keywords = dir(HelperModule("foo.py"))
+
+    def Run(self):
+        for helper in self.core.plugins['TemplateHelper'].entries.values():
+            if self.HandlesFile(helper):
+                self.check_helper(helper.name)
+
+    def check_helper(self, helper):
+        """ check a helper module for export errors """
+        module_name = MODULE_RE.search(helper).group(1)
+
+        try:
+            module = imp.load_source(safe_module_name(module_name), helper)
+        except:  # pylint: disable=W0702
+            err = sys.exc_info()[1]
+            self.LintError("templatehelper-import-error",
+                           "Failed to import %s: %s" %
+                           (helper, err))
+            return
+
+        if not hasattr(module, "__export__"):
+            self.LintError("templatehelper-no-export",
+                           "%s has no __export__ list" % helper)
+            return
+        elif not isinstance(module.__export__, list):
+            self.LintError("templatehelper-nonlist-export",
+                           "__export__ is not a list in %s" % helper)
+            return
+
+        for sym in module.__export__:
+            if not hasattr(module, sym):
+                self.LintError("templatehelper-nonexistent-export",
+                               "%s: exported symbol %s does not exist" %
+                               (helper, sym))
+            elif sym in self.reserved_keywords:
+                self.LintError("templatehelper-reserved-export",
+                               "%s: exported symbol %s is reserved" %
+                               (helper, sym))
+            elif sym.startswith("_"):
+                self.LintError("templatehelper-underscore-export",
+                               "%s: exported symbol %s starts with underscore"
+                               % (helper, sym))
+
+    @classmethod
+    def Errors(cls):
+        return {"templatehelper-import-error": "error",
+                "templatehelper-no-export": "error",
+                "templatehelper-nonlist-export": "error",
+                "templatehelper-nonexistent-export": "error",
+                "templatehelper-reserved-export": "error",
+                "templatehelper-underscore-export": "warning"}
diff --git a/src/lib/Server/Plugins/__init__.py b/src/lib/Server/Plugins/__init__.py
index c69c37452..b39793290 100644
--- a/src/lib/Server/Plugins/__init__.py
+++ b/src/lib/Server/Plugins/__init__.py
@@ -29,6 +29,7 @@ __all__ = [
            'Svcmgr',
            'Svn',
            'TCheetah',
+           'TemplateHelper',
            'Trigger',
            'SGenshi',
            'TGenshi',