try to get details about a genshi error

1 files changed, 61 insertions, 4 deletions

diff --git a/src/lib/Bcfg2/Server/Plugins/Cfg/CfgGenshiGenerator.py b/src/lib/Bcfg2/Server/Plugins/Cfg/CfgGenshiGenerator.py
index 5447717d8..277a26f97 100644
--- a/src/lib/Bcfg2/Server/Plugins/Cfg/CfgGenshiGenerator.py
+++ b/src/lib/Bcfg2/Server/Plugins/Cfg/CfgGenshiGenerator.py
@@ -1,5 +1,7 @@
+import re
 import sys
 import logging
+import traceback
 import Bcfg2.Server.Plugin
 from Bcfg2.Server.Plugins.Cfg import CfgGenerator
 
@@ -8,6 +10,7 @@ logger = logging.getLogger(__name__)
 try:
     import genshi.core
     from genshi.template import TemplateLoader, NewTextTemplate
+    from genshi.template.eval import UndefinedError
     have_genshi = True
 except ImportError:
     TemplateLoader = None
@@ -25,6 +28,7 @@ def removecomment(stream):
 class CfgGenshiGenerator(CfgGenerator):
     __extensions__ = ['genshi']
     __loader_cls__ = TemplateLoader
+    pyerror_re = re.compile('<\w+ u?[\'"](.*?)\s*\.\.\.[\'"]>')
 
     def __init__(self, fname, spec, encoding):
         CfgGenerator.__init__(self, fname, spec, encoding)
@@ -47,10 +51,63 @@ class CfgGenshiGenerator(CfgGenerator):
                                    metadata=metadata,
                                    path=self.name).filter(removecomment)
         try:
-            return stream.render('text', encoding=self.encoding,
-                                 strip_whitespace=False)
-        except TypeError:
-            return stream.render('text', encoding=self.encoding)
+            try:
+                return stream.render('text', encoding=self.encoding,
+                                     strip_whitespace=False)
+            except TypeError:
+                return stream.render('text', encoding=self.encoding)
+        except UndefinedError:
+            # a failure in a genshi expression _other_ than %{ python ... %}
+            err = sys.exc_info()[1]
+            stack = traceback.extract_tb(sys.exc_info()[2])
+            for quad in stack:
+                if quad[0] == self.name:
+                    logger.error("Cfg: Error rendering %s at %s: %s" %
+                                 (fname, quad[2], err))
+                    break
+            raise
+        except:
+            # a failure in a %{ python ... %} block -- the snippet in
+            # the traceback is just the beginning of the block.
+            err = sys.exc_info()[1]
+            stack = traceback.extract_tb(sys.exc_info()[2])
+            (filename, lineno, func, text) = stack[-1]
+            # this is horrible, and I deeply apologize to whoever gets
+            # to maintain this after I go to the Great Beer Garden in
+            # the Sky.  genshi is incredibly opaque about what's being
+            # executed, so the only way I can find to determine which
+            # {% python %} block is being executed -- if there are
+            # multiples -- is to iterate through them and match the
+            # snippet of the first line that's in the traceback with
+            # the first non-empty line of the block.
+            execs = [contents
+                     for etype, contents, loc in self.template.stream
+                     if etype == self.template.EXEC]
+            contents = None
+            if len(execs) == 1:
+                contents = execs[0]
+            elif len(execs) > 1:
+                match = pyerror_re.match(func)
+                if match:
+                    firstline = match.group(0)
+                    for pyblock in execs:
+                        if pyblock.startswith(firstline):
+                            contents = pyblock
+                            break
+            # else, no EXEC blocks -- WTF?
+            if contents:
+                # we now have the bogus block, but we need to get the
+                # offending line.  To get there, we do (line number
+                # given in the exception) - (firstlineno from the
+                # internal genshi code object of the snippet) + 1 =
+                # (line number of the line with an error within the
+                # block, with all multiple line breaks elided to a
+                # single line break)
+                real_lineno = lineno - contents.code.co_firstlineno
+                src = re.sub(r'\n\n+', '\n', contents.source).splitlines()
+                logger.error("Cfg: Error rendering %s at %s: %s" %
+                             (fname, src[real_lineno], err))
+            raise
 
     def handle_event(self, event):
         if event.code2str() == 'deleted':