bpo-31170: Write unit test for Expat 2.2.4 UTF-8 bug (#3570) (#3745)

Non-regression tests for the Expat 2.2.3 UTF-8 decoder bug. (cherry picked from commit e6d9fcbb)

bpo-31170: Write unit test for Expat 2.2.4 UTF-8 bug (#3570) (#3745)
Non-regression tests for the Expat 2.2.3 UTF-8 decoder bug. (cherry picked from commit e6d9fcbb)
5f5da728 · Victor Stinner · GitHub · cf7197ae · 5f5da728 · 5f5da728
Commit 5f5da728 authored Sep 25, 2017 by Victor Stinner Committed by GitHub Sep 25, 2017
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Lib/test/test_xml_etree.py Lib/test/test_xml_etree.py +31 -0

Lib/test/xmltestdata/expat224_utf8_bug.xml Lib/test/xmltestdata/expat224_utf8_bug.xml +2 -0

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--- a/Lib/test/test_xml_etree.py
+++ b/Lib/test/test_xml_etree.py
@@ -30,6 +30,7 @@ ET = None

 SIMPLE_XMLFILE = findfile("simple.xml", subdir="xmltestdata")
 SIMPLE_NS_XMLFILE = findfile("simple-ns.xml", subdir="xmltestdata")
+UTF8_BUG_XMLFILE = findfile("expat224_utf8_bug.xml", subdir="xmltestdata")

 SAMPLE_XML = """\
 <body>
@@ -1494,6 +1495,36 @@ class BugsTest(unittest.TestCase):
        ET.register_namespace('test10777', 'http://myuri/')
        ET.register_namespace('test10777', 'http://myuri/')

+    def check_expat224_utf8_bug(self, text):
+        xml = b'<a b="%s"/>' % text
+        root = ET.XML(xml)
+        self.assertEqual(root.get('b'), text.decode('utf-8'))
+
+    def test_expat224_utf8_bug(self):
+        # bpo-31170: Expat 2.2.3 had a bug in its UTF-8 decoder.
+        # Check that Expat 2.2.4 fixed the bug.
+        #
+        # Test buffer bounds at odd and even positions.
+
+        text = b'\xc3\xa0' * 1024
+        self.check_expat224_utf8_bug(text)
+
+        text = b'x' + b'\xc3\xa0' * 1024
+        self.check_expat224_utf8_bug(text)
+
+    def test_expat224_utf8_bug_file(self):
+        with open(UTF8_BUG_XMLFILE, 'rb') as fp:
+            raw = fp.read()
+        root = ET.fromstring(raw)
+        xmlattr = root.get('b')
+
+        # "Parse" manually the XML file to extract the value of the 'b'
+        # attribute of the <a b='xxx' /> XML element
+        text = raw.decode('utf-8').strip()
+        text = text.replace('\r\n', ' ')
+        text = text[6:-4]
+        self.assertEqual(root.get('b'), text)
+

 # --------------------------------------------------------------------


--- a/Lib/test/xmltestdata/expat224_utf8_bug.xml
+++ b/Lib/test/xmltestdata/expat224_utf8_bug.xml
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+弘治戊午仲冬望日慈溪杨子器衵于海虞官舍序毕诗部' />