Issue #11235: Fix OverflowError when trying to import a source file whose modification time doesn't fit in a 32-bit timestamp.

Lib/importlib/test/source/test_file_loader.py

@@ -123,6 +123,23 @@ class SimpleTest(unittest.TestCase):
             pycache = os.path.dirname(imp.cache_from_source(file_path))
             shutil.rmtree(pycache)
 
+    def test_timestamp_overflow(self):
+        # When a modification timestamp is larger than 2**32, it should be
+        # truncated rather than raise an OverflowError.
+        with source_util.create_modules('_temp') as mapping:
+            source = mapping['_temp']
+            compiled = imp.cache_from_source(source)
+            with open(source, 'w') as f:
+                f.write("x = 5")
+            os.utime(source, (2 ** 33, 2 ** 33))
+            loader = _bootstrap._SourceFileLoader('_temp', mapping['_temp'])
+            mod = loader.load_module('_temp')
+            # Sanity checks.
+            self.assertEqual(mod.__cached__, compiled)
+            self.assertEqual(mod.x, 5)
+            # The pyc file was created.
+            os.stat(compiled)
+
 
 class BadBytecodeTest(unittest.TestCase):
 

Lib/test/test_import.py

@@ -306,6 +306,18 @@ class ImportTests(unittest.TestCase):
             """))
         script_helper.assert_python_ok(testfn)
 
+    def test_timestamp_overflow(self):
+        # A modification timestamp larger than 2**32 should not be a problem
+        # when importing a module (issue #11235).
+        source = TESTFN + ".py"
+        compiled = imp.cache_from_source(source)
+        with open(source, 'w') as f:
+            pass
+        os.utime(source, (2 ** 33, 2 ** 33))
+        __import__(TESTFN)
+        # The pyc file was created.
+        os.stat(compiled)
+
 
 class PycRewritingTests(unittest.TestCase):
     # Test that the `co_filename` attribute on code objects always points

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.3 Alpha 1?
 Core and Builtins
 -----------------
 
+- Issue #11235: Fix OverflowError when trying to import a source file whose
+  modification time doesn't fit in a 32-bit timestamp.
+
 - Issue #12705: A SyntaxError exception is now raised when attempting to
   compile multiple statements as a single interactive statement.
 

Python/import.c

@@ -1478,14 +1478,11 @@ load_source_module(PyObject *name, PyObject *pathname, FILE *fp)
     }
 #if SIZEOF_TIME_T > 4
     /* Python's .pyc timestamp handling presumes that the timestamp fits
-       in 4 bytes. This will be fine until sometime in the year 2038,
-       when a 4-byte signed time_t will overflow.
+       in 4 bytes. Since the code only does an equality comparison,
+       ordering is not important and we can safely ignore the higher bits
+       (collisions are extremely unlikely).
      */
-    if (st.st_mtime >> 32) {
-        PyErr_SetString(PyExc_OverflowError,
-            "modification time overflows a 4 byte field");
-        goto error;
-    }
+    st.st_mtime &= 0xFFFFFFFF;
 #endif
     if (PyUnicode_READY(pathname) < 0)
         return NULL;