Collector #574: Fixed write on HEAD requests caused by overzealous ETag support.

doc/CHANGES.txt

@@ -6,9 +6,8 @@ Zope Changes
 
     Bugs Fixed
 
-      - Fixed bug in manage_editProperties which used an incorrect default
-        for several types of property when they were not found in the
-        REQUEST.
+      - Collector #574: Fixed write on HEAD requests caused by overzealous
+        ETag support.
 
       - Fixed broken management form for TopicIndexes.
     

lib/python/webdav/EtagSupport.py

@@ -11,7 +11,7 @@
 #
 ##############################################################################
 
-__version__ = "$Revision: 1.8 $"[11:-2]
+__version__ = "$Revision: 1.9 $"[11:-2]
 
 
 import time, Interface, re
@@ -66,9 +66,11 @@ class EtagSupport:
     """
     __implements__ = (EtagBaseInterface,)
 
-    def http__etag(self):
+    def http__etag(self, readonly=0):
         try: etag = self.__etag
         except AttributeError:
+            if readonly: # Don't refresh the etag on reads
+                return
             self.http__refreshEtag()
             etag = self.__etag
         return etag

lib/python/webdav/Resource.py

@@ -13,7 +13,7 @@
 
 """WebDAV support - resource objects."""
 
-__version__='$Revision: 1.53 $'[11:-2]
+__version__='$Revision: 1.54 $'[11:-2]
 
 import sys, os,  mimetypes, davcmds, ExtensionClass, Lockable
 from common import absattr, aq_base, urlfix, rfc1123_date, tokenFinder, urlbase
@@ -167,7 +167,9 @@ class Resource(ExtensionClass.Base, Lockable.LockableItem):
             mtime=rfc1123_date(self._p_mtime)
             RESPONSE.setHeader('Last-Modified', mtime)
         if hasattr(aq_base(self), 'http__etag'):
-            RESPONSE.setHeader('Etag', self.aq_base.http__etag())
+            etag = self.http__etag(readonly=1)
+            if etag:
+                RESPONSE.setHeader('Etag', etag)
         RESPONSE.setStatus(200)
         return RESPONSE