gh-113537: support loads str in plistlib.loads (#113582)

Add support for loading XML plists from a string value instead of a only bytes value.

Lib/plistlib.py

@@ -906,6 +906,11 @@ def loads(value, *, fmt=None, dict_type=dict, aware_datetime=False):
     """Read a .plist file from a bytes object.
     Return the unpacked root object (which usually is a dictionary).
     """
+    if isinstance(value, str):
+        if fmt == FMT_BINARY:
+            raise TypeError("value must be bytes-like object when fmt is "
+                            "FMT_BINARY")
+        value = value.encode()
     fp = BytesIO(value)
     return load(fp, fmt=fmt, dict_type=dict_type, aware_datetime=aware_datetime)
 

Lib/test/test_plistlib.py

@@ -510,6 +510,19 @@ class TestPlistlib(unittest.TestCase):
         data2 = plistlib.dumps(pl2)
         self.assertEqual(data, data2)
 
+    def test_loads_str_with_xml_fmt(self):
+        pl = self._create()
+        b = plistlib.dumps(pl)
+        s = b.decode()
+        self.assertIsInstance(s, str)
+        pl2 = plistlib.loads(s)
+        self.assertEqual(pl, pl2)
+
+    def test_loads_str_with_binary_fmt(self):
+        msg = "value must be bytes-like object when fmt is FMT_BINARY"
+        with self.assertRaisesRegex(TypeError, msg):
+            plistlib.loads('test', fmt=plistlib.FMT_BINARY)
+
     def test_indentation_array(self):
         data = [[[[[[[[{'test': b'aaaaaa'}]]]]]]]]
         self.assertEqual(plistlib.loads(plistlib.dumps(data)), data)