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Date:      Fri, 16 Jun 2006 05:50:34 +0000 (UTC)
From:      Joseph Koshy <jkoshy@FreeBSD.org>
To:        FreeBSD-gnats-submit@FreeBSD.org
Subject:   ports/99009: py-yaml ZeroDivisionError exception
Message-ID:  <20060616055034.1604D16A47C@hub.freebsd.org>
Resent-Message-ID: <200606160600.k5G60bwl070039@freefall.freebsd.org>
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>Number:         99009
>Category:       ports
>Synopsis:       py24-yaml fails to load
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-ports-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jun 16 06:00:35 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Joseph Koshy
>Release:        FreeBSD 7.0-CURRENT i386
>Organization:
The FreeBSD Project
>Environment:

System: FreeBSD orthanc-5 7.0-CURRENT FreeBSD 7.0-CURRENT #23: Mon Jun 5 05:25:05 IST 2006 root@orthanc-5:/home/obj-current/home/src-current/sys/FCPI-OPT i386

>Description:

Python throws a ZeroDivisionError exception when the yaml library is used.

>How-To-Repeat:

Try 'import yaml' in Python.

  % python
  Python 2.4.2 (#2, Feb 20 2006, 21:55:20)
  [GCC 2.95.4 20020320 [FreeBSD]] on freebsd4
  Type "help", "copyright", "credits" or "license" for more information.
  >>> import yaml
  Traceback (most recent call last):
    File "<stdin>", line 1, in ?
    File "/usr/local/lib/python2.4/site-packages/yaml/__init__.py", line 8, in ?
      from loader import *
    File "/usr/local/lib/python2.4/site-packages/yaml/loader.py", line 8, in ?
      from constructor import *
    File "/usr/local/lib/python2.4/site-packages/yaml/constructor.py", line 187, in ?
      class SafeConstructor(BaseConstructor):
    File "/usr/local/lib/python2.4/site-packages/yaml/constructor.py", line 235, in SafeConstructor
      nan_value = inf_value/inf_value
  ZeroDivisionError: float division

>Fix:

The following patch from the Py-Yaml website fixes the problem.

Index: pyyaml/trunk/lib/yaml/constructor.py
===================================================================
--- pyyaml/trunk/lib/yaml/constructor.py (revision 147)
+++ pyyaml/trunk/lib/yaml/constructor.py (revision 168)
@@ -232,5 +232,7 @@
             return sign*int(value)
 
-    inf_value = 1e300000
+    inf_value = 1e300
+    while repr(inf_value) != repr(inf_value*inf_value):
+        inf_value *= inf_value
     nan_value = inf_value/inf_value
 
Index: pyyaml/trunk/lib/yaml/representer.py
===================================================================
--- pyyaml/trunk/lib/yaml/representer.py (revision 152)
+++ pyyaml/trunk/lib/yaml/representer.py (revision 168)
@@ -193,7 +193,12 @@
         return self.represent_scalar(u'tag:yaml.org,2002:int', unicode(data))
 
-    repr_pos_inf = repr(1e300000)
-    repr_neg_inf = repr(-1e300000)
-    repr_nan = repr(1e300000/1e300000)
+    inf_value = 1e300
+    while repr(inf_value) != repr(inf_value*inf_value):
+        inf_value *= inf_value
+    nan_value = inf_value/inf_value
+
+    repr_pos_inf = repr(inf_value)
+    repr_neg_inf = repr(-inf_value)
+    repr_nan = repr(inf_value/inf_value)
 
     def represent_float(self, data):

>Release-Note:
>Audit-Trail:
>Unformatted:

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