Closes #12291: Fixed bug which was found when doing multiple loads from one stream.

Lib/importlib/test/source/test_file_loader.py

@@ -214,7 +214,7 @@ class BadBytecodeTest(unittest.TestCase):
                                                 lambda bc: bc[:8] + b'<test>',
                                                 del_source=del_source)
             file_path = mapping['_temp'] if not del_source else bytecode_path
-            with self.assertRaises(ValueError):
+            with self.assertRaises(EOFError):
                 self.import_(file_path, '_temp')
 
     def _test_bad_magic(self, test, *, del_source=False):

Lib/test/test_marshal.py

@@ -211,6 +211,30 @@ class BugsTestCase(unittest.TestCase):
         invalid_string = b'l\x02\x00\x00\x00\x00\x00\x00\x00'
         self.assertRaises(ValueError, marshal.loads, invalid_string)
 
+    def test_multiple_dumps_and_loads(self):
+        # Issue 12291: marshal.load() should be callable multiple times
+        # with interleaved data written by non-marshal code
+        # Adapted from a patch by Engelbert Gruber.
+        data = (1, 'abc', b'def', 1.0, (2, 'a', ['b', b'c']))
+        for interleaved in (b'', b'0123'):
+            ilen = len(interleaved)
+            positions = []
+            try:
+                with open(support.TESTFN, 'wb') as f:
+                    for d in data:
+                        marshal.dump(d, f)
+                        if ilen:
+                            f.write(interleaved)
+                        positions.append(f.tell())
+                with open(support.TESTFN, 'rb') as f:
+                    for i, d in enumerate(data):
+                        self.assertEqual(d, marshal.load(f))
+                        if ilen:
+                            f.read(ilen)
+                        self.assertEqual(positions[i], f.tell())
+            finally:
+                support.unlink(support.TESTFN)
+
 
 def test_main():
     support.run_unittest(IntTestCase,

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.2.1 release candidate 2?
 Core and Builtins
 -----------------
 
+- Issue #12291: You can now load multiple marshalled objects from a stream,
+  with other data interleaved between marshalled objects.
+
 - Issue #12084: os.stat on Windows now works properly with relative symbolic
   links when called from any directory.