--- decode.py	2008-10-02 09:17:45.000000000 +0200
+++ decode.new.py	2008-10-02 10:15:27.000000000 +0200
@@ -16,10 +16,13 @@
 
 $Id: decode.py 70914 2006-10-25 19:30:03Z yuppie $
 """
-
+from zope import interface
 from zope.publisher.browser import isCGI_NAME
 from zope.i18n.interfaces import IUserPreferredCharsets
 
+class IFixedUpRequest(interface.Interface):
+    pass
+
 # taken and adapted from zope.publisher.browser.BrowserRequest
 def _decode(text, charsets):
     """Try to decode the text using one of the available charsets.
@@ -33,22 +36,26 @@
     return text
 
 def processInputs(request, charsets=None):
-    if charsets is None:
-        envadapter = IUserPreferredCharsets(request)
-        charsets = envadapter.getPreferredCharsets() or ['utf-8']
-
-    for name, value in request.form.items():
-        if not (isCGI_NAME(name) or name.startswith('HTTP_')):
-            if isinstance(value, str):
-                request.form[name] = _decode(value, charsets)
-            elif isinstance(value, list):
-                request.form[name] = [ _decode(val, charsets)
-                                       for val in value
-                                       if isinstance(val, str) ]
-            elif isinstance(value, tuple):
-                request.form[name] = tuple([ _decode(val, charsets)
-                                             for val in value
-                                             if isinstance(val, str) ])
+
+    if not IFixedUpRequest.providedBy(request):
+        interface.alsoProvides(request, IFixedUpRequest)
+
+        if charsets is None:
+            envadapter = IUserPreferredCharsets(request)
+            charsets = envadapter.getPreferredCharsets() or ['utf-8']
+
+        for name, value in request.form.items():
+            if not (isCGI_NAME(name) or name.startswith('HTTP_')):
+                if isinstance(value, str):
+                    request.form[name] = _decode(value, charsets)
+                elif isinstance(value, list):
+                    request.form[name] = [ _decode(val, charsets)
+                                           for val in value
+                                           if isinstance(val, str) ]
+                elif isinstance(value, tuple):
+                    request.form[name] = tuple([ _decode(val, charsets)
+                                                 for val in value
+                                                 if isinstance(val, str) ])
 
 def setPageEncoding(request):
     """Set the encoding of the form page via the Content-Type header.