[FIX] fields.function: make sure all binary values can always be serialized as valid XML

Nnormally, binary fields should be 7-bit ASCII base64-encoded data, but sometimes
it's not the case, so we do additional sanity checks to make sure the binary values
can pass safely via xmlrpc as strings.

As a last resort we coerce the binary values to unicode to make sure they can
be safely serialized as utf-8-encoded values, always valid XML characters.
When this happens, decoding on the other endpoint is not likely to produce
the expected output, but this isjust a safety mechanism(in these cases base64
data or xmlrpc. Binary values should be returned instead by the function field.

In a future version we should probably switch to using XMLRPC Binary types always for
passing fields.binary values, but this requires more refactoring.

lp bug: https://launchpad.net/bugs/670778 fixed

bzr revid: odo@openerp.com-20101209230742-gwf8e4zvmk43k6ln

bin/osv/fields.py

@@ -33,12 +33,12 @@
 #
 import datetime as DT
 import string
-import netsvc
 import sys
 import warnings
-
+import xmlrpclib
 from psycopg2 import Binary
 
+import netsvc
 import tools
 from tools.translate import _
 
@@ -673,6 +673,37 @@ def get_nice_size(a):
         size = 0
     return (x, tools.human_size(size))
 
+def sanitize_binary_value(dict_item):
+    # binary fields should be 7-bit ASCII base64-encoded data,
+    # but we do additional sanity checks to make sure the values
+    # will are not something else that won't pass via xmlrpc
+    index, value = dict_item
+    if isinstance(value, (xmlrpclib.Binary, tuple, list, dict)):
+        # these builtin types are meant to pass untouched
+        return index, value
+
+    # For all other cases, handle the value as a binary string:
+    # it could be a 7-bit ASCII string (e.g base64 data), but also
+    # any 8-bit content from files, with byte values that cannot
+    # be passed inside XML!
+    # See for more info:
+    #  - http://bugs.python.org/issue10066
+    #  - http://www.w3.org/TR/2000/REC-xml-20001006#NT-Char
+    #
+    # One solution is to convert the byte-string to unicode,
+    # so it gets serialized as utf-8 encoded data (always valid XML)
+    # If invalid XML byte values were present, tools.ustr() uses
+    # the Latin-1 codec as fallback, which converts any 8-bit
+    # byte value, resulting in valid utf-8-encoded bytes
+    # in the end:
+    #  >>> unicode('\xe1','latin1').encode('utf8') == '\xc3\xa1'
+    # Note: when this happens, decoding on the other endpoint
+    # is not likely to produce the expected output, but this is
+    # just a safety mechanism (in these cases base64 data or
+    # xmlrpc.Binary values should be used instead
+    return index, tools.ustr(value)
+
+
 # ---------------------------------------------------------
 # Function fields
 # ---------------------------------------------------------
@@ -763,9 +794,13 @@ class function(_column):
                     if res[r] and res[r] in dict_names:
                         res[r] = (res[r], dict_names[res[r]])
 
-        if self._type == 'binary' and context.get('bin_size', False):
-            # convert the data returned by the function with the size of that data...
-            res = dict(map( get_nice_size, res.items()))
+        if self._type == 'binary':
+            if context.get('bin_size', False):
+                # client requests only the size of binary fields
+                res = dict(map(get_nice_size, res.items()))
+            else:
+                res = dict(map(sanitize_binary_value, res.items()))
+
         if self._type == "integer":
             for r in res.keys():
                 # Converting value into string so that it does not affect XML-RPC Limits