From 8112ea2360b1a536b4931fd13173a7bbe5ac7aa1 Mon Sep 17 00:00:00 2001
From: Christian Heimes <christian@cheimes.de>
Date: Mon, 24 Sep 2012 13:17:08 +0200
Subject: [PATCH] Issue #16012: Fix a regression in pyexpat. The parser's
 UseForeignDTD() method doesn't require an argument again.

---
 Lib/test/test_pyexpat.py | 55 +++++++++++++++++++++++++++++++++++++++-
 Misc/NEWS                |  6 +++++
 Modules/pyexpat.c        |  2 +-
 3 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_pyexpat.py b/Lib/test/test_pyexpat.py
index 75b031ac178..b911a2058cc 100644
--- a/Lib/test/test_pyexpat.py
+++ b/Lib/test/test_pyexpat.py
@@ -588,6 +588,58 @@ class MalformedInputText(unittest.TestCase):
         except expat.ExpatError as e:
             self.assertEqual(str(e), 'XML declaration not well-formed: line 1, column 14')
 
+class ForeignDTDTests(unittest.TestCase):
+    """
+    Tests for the UseForeignDTD method of expat parser objects.
+    """
+    def test_use_foreign_dtd(self):
+        """
+        If UseForeignDTD is passed True and a document without an external
+        entity reference is parsed, ExternalEntityRefHandler is first called
+        with None for the public and system ids.
+        """
+        handler_call_args = []
+        def resolve_entity(context, base, system_id, public_id):
+            handler_call_args.append((public_id, system_id))
+            return 1
+
+        parser = expat.ParserCreate()
+        parser.UseForeignDTD(True)
+        parser.SetParamEntityParsing(expat.XML_PARAM_ENTITY_PARSING_ALWAYS)
+        parser.ExternalEntityRefHandler = resolve_entity
+        parser.Parse("<?xml version='1.0'?><element/>")
+        self.assertEqual(handler_call_args, [(None, None)])
+
+        # test UseForeignDTD() is equal to UseForeignDTD(True)
+        handler_call_args[:] = []
+
+        parser = expat.ParserCreate()
+        parser.UseForeignDTD()
+        parser.SetParamEntityParsing(expat.XML_PARAM_ENTITY_PARSING_ALWAYS)
+        parser.ExternalEntityRefHandler = resolve_entity
+        parser.Parse("<?xml version='1.0'?><element/>")
+        self.assertEqual(handler_call_args, [(None, None)])
+
+    def test_ignore_use_foreign_dtd(self):
+        """
+        If UseForeignDTD is passed True and a document with an external
+        entity reference is parsed, ExternalEntityRefHandler is called with
+        the public and system ids from the document.
+        """
+        handler_call_args = []
+        def resolve_entity(context, base, system_id, public_id):
+            handler_call_args.append((public_id, system_id))
+            return 1
+
+        parser = expat.ParserCreate()
+        parser.UseForeignDTD(True)
+        parser.SetParamEntityParsing(expat.XML_PARAM_ENTITY_PARSING_ALWAYS)
+        parser.ExternalEntityRefHandler = resolve_entity
+        parser.Parse(
+            "<?xml version='1.0'?><!DOCTYPE foo PUBLIC 'bar' 'baz'><element/>")
+        self.assertEqual(handler_call_args, [("bar", "baz")])
+
+
 def test_main():
     run_unittest(SetAttributeTest,
                  ParseTest,
@@ -598,7 +650,8 @@ def test_main():
                  PositionTest,
                  sf1296433Test,
                  ChardataBufferTest,
-                 MalformedInputText)
+                 MalformedInputText,
+                 ForeignDTDTests)
 
 if __name__ == "__main__":
     test_main()
diff --git a/Misc/NEWS b/Misc/NEWS
index 84d4bd1910c..bbdd5e54338 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -379,6 +379,12 @@ Library
 - Issue #6884: Fix long-standing bugs with MANIFEST.in parsing in distutils
   on Windows.
 
+Extension Modules
+-----------------
+
+- Issue #16012: Fix a regression in pyexpat. The parser's UseForeignDTD()
+  method doesn't require an argument again.
+
 Tests
 -----
 
diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index 4d9a1e59849..f2691136ca8 100644
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -1176,7 +1176,7 @@ xmlparse_UseForeignDTD(xmlparseobject *self, PyObject *args)
     PyObject *flagobj = NULL;
     int flag = 1;
     enum XML_Error rc;
-    if (!PyArg_ParseTuple(args, "O:UseForeignDTD", &flagobj))
+    if (!PyArg_ParseTuple(args, "|O:UseForeignDTD", &flagobj))
         return NULL;
     if (flagobj != NULL) {
         flag = PyObject_IsTrue(flagobj);