Disable surrogate check for ucs2 (#5039)

* _SURROGATE_PATTERN check for ucs4
Skip some test for ucs2 by sys.maxunicode

python/google/protobuf/internal/decoder.py

@@ -83,7 +83,9 @@ __author__ = 'kenton@google.com (Kenton Varda)'
 import struct
 
 import six
+import sys
 
+_UCS2_MAXUNICODE = 65535
 if six.PY3:
   long = int
 else:
@@ -550,7 +552,8 @@ def StringDecoder(field_number, is_repeated, is_packed, key, new_default,
       e.reason = '%s in field: %s' % (e, key.full_name)
       raise
 
-    if is_strict_utf8 and six.PY2:
+    if is_strict_utf8 and six.PY2 and sys.maxunicode > _UCS2_MAXUNICODE:
+      # Only do the check for python2 ucs4 when is_strict_utf8 enabled
       if _SURROGATE_PATTERN.search(value):
         reason = ('String field %s contains invalid UTF-8 data when parsing'
                   'a protocol buffer: surrogates not allowed. Use'

python/google/protobuf/internal/message_test.py

@@ -81,6 +81,7 @@ from google.protobuf.internal import testing_refleaks
 from google.protobuf import message
 from google.protobuf.internal import _parameterized
 
+UCS2_MAXUNICODE = 65535
 if six.PY3:
   long = int
 
@@ -2209,7 +2210,9 @@ class Proto3Test(BaseTestCase):
     msg.map_int32_int32[35] = 64
     msg.map_string_foreign_message['foo'].c = 5
     self.assertEqual(0, len(msg.FindInitializationErrors()))
-
+ 
+  @unittest.skipIf(sys.maxunicode == UCS2_MAXUNICODE,
+                   'Skip for ucs2')
   def testStrictUtf8Check(self):
     # Test u'\ud801' is rejected at parser in both python2 and python3.
     serialized = (b'r\x03\xed\xa0\x81')
@@ -2259,7 +2262,8 @@ class Proto3Test(BaseTestCase):
       unittest_proto3_arena_pb2.TestAllTypes(
           optional_string=u'\ud801\ud801')
 
-  @unittest.skipIf(six.PY3, 'Surrogates are rejected at setters in Python3')
+  @unittest.skipIf(six.PY3 or sys.maxunicode == UCS2_MAXUNICODE,
+                   'Surrogates are rejected at setters in Python3')
   def testSurrogatesInPython2(self):
     # Test optional_string=u'\ud801\udc01'.
     # surrogate pair is acceptable in python2.